Patent Publication Number: US-11660802-B2

Title: Continuous blow moulding machine, preforms, system and process

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 16/649,580, filed on Mar. 20, 2020, which is an application under 35 U.S.C. 371 of International Application No. PCT/AU2018/051030 filed on Sep. 20, 2018, the entire contents of each of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the equipment and method for the production of stretch-blow-moulded polymer containers from injection-moulded preforms. 
     BACKGROUND 
     The process of stretch-blow-moulding polymer containers from a prior injection moulded preform is long established in the art. Generally, preforms, as injection moulded, comprise an elongate cylindrical body portion and a neck. In the stretch blow-moulding process, the preform enters a die, held by the neck which retains its injection moulded shape, and the body is firstly mechanically stretched in at least one direction followed by the injection of air to force the polymer material into the desired shape as defined by the die cavity and also stretching the polymer material in at least one other direction—termed biaxial orientation. Where time has elapsed between the injection moulding of the preforms and their entry into the blow moulding process so that the preforms have cooled to ambient temperature, a preheating process is applied before preforms enter the blow mould die. 
     The process is considerably more complicated if the preform is rotationally non-symmetric and, as in the present case, is injection moulded with an integrally attached handle, and more particularly if the handle is in the form of a loop, integrally attached at two points on the body of the preform. The complication arises primarily from the need to control the orientation of the handle and to correctly preheat the body of the preform while protecting the handle from excessive heat absorption, as well as the correct insertion of the preform into the stretch-blow-moulding die. 
     Such a preform and systems for its transformation into a container with integral handle are disclosed in WO2007101309. The entire disclosure of WO2007101309 is incorporated hereby cross reference. In that disclosure, preforms enter a production machine such as schematically shown in  FIGS.  55  and  72    of that document after orientation of the handle, which orientation is then maintained, through the preheating stage and into the stretch-blow-moulding die. 
     In the systems disclosed in WO2007101309 however, the process of production is discontinuous or ‘batch’; that is, the production machines progress preforms incrementally, pausing at each index to allow for pick and place loading of preforms, their insertion into a supporting mandrel and the entry into and exit from the stretch blow-moulding cavities, while the preforms are stopped for each moulding cycle. A disadvantage of this incremental processing is that it is clearly less efficient than a continuous process. 
     The present invention relates to a machine and process for the stretch blow moulding of preforms with an integral handle in a continuous feed, thus non-incrementing system. Because of the several stages in the process, the requirements of establishing handle orientation, the preheating stage and the stretch-blow-moulding stage as well as the removal of finished containers, requires the transfer of preforms between rotating in-feed, preheating, moulding and transport elements of the system. A continuous process makes these processes and transfers for a preform with integral handle, considerably more complex. 
     A system for handling a non-rotationally symmetric preform requiring a known orientation for selective preheating and prior to loading into a stretch-blow-moulding die was disclosed in U.S. Pat. No. 8,632,333 B2. In the arrangement of this patent orientation is established with reference to a small reference tab or notch, but this preform not having a handle there is no need for orientation relative a heat shield. 
     US 2012/0048683 also discloses a continuously rotating blow moulding system in which special precautions are taken against deformation of preforms due to centrifugal forces by specific orientation of the preforms passing through the system. Although it is noted that such orientation may be of benefit for non-symmetric preforms, for example those with a handle, there is no disclosure of orientation of a preform for entry into a heat shield. 
     U.S. Pat. No. 6,779,651 specifically teaches the importance of orientation of preforms with handles prior to introduction of the preform into the stretch-blow-moulding die. There is however no suggestion that the handle requires shielding by means of a heat shield so that there is no arrangement in this patent of the control of orientation to marry the handle with a heat shield. 
     A suit of patents and applications to Thibodeau, U.S. D746,142 S; U.S. Pat. Nos. 8,524,143 B2; 9,499,302 B2 and WO2015/112440 A1 are drawn to the production of containers with integral handle stretch-blow-moulded from injection moulded preforms with integral handles. However, in contrast with the arrangement of the present application as set out below, the handle of a container according to Thibodeau is of radically different shape to the handle as injection moulded with the preform, being subjected to a sort of uncurling during the stretch-blow-moulding phase. 
     Another continuously rotating blow-moulding system is disclosed in U.S. Pat. No. 5,683,729 in which mechanisms for the transfer of preforms between various stages of the system are described. There is however no disclosure of preforms with integral handles and thus no treatment of special orientation of the preforms. 
     It is an object of the present invention to address or at least ameliorate some of the above disadvantages. 
     NOTES 
     The term “comprising” (and grammatical variations thereof) is used in this specification in the inclusive sense of “having” or “including”, and not in the exclusive sense of “consisting only of”. 
     The above discussion of the prior art in the Background of the invention, is not an admission that any information discussed therein is citable prior art or part of the common general knowledge of persons skilled in the art in any country. 
     SUMMARY OF INVENTION 
     Definitions 
     Continuous preform feed: In this specification, continuous preform feed occurs where preforms are advanced at constant velocity from an entry location to an exit location along a path. This is to be distinguished from a batch mode operation where the preform feed advances and then stops whilst a blow mould operation takes place. 
     Non-symmetric preform: In this specification, a non-symmetric preform is a preform which is not symmetric about its longitudinal axis. The primary source of non-symmetry occurs where the preform incorporates an integral handle. In certain embodiments the preform walls are also a source of non-symmetry. 
     Integral handle preform: In this specification, an integral handle preform is a non-symmetric preform which has a handle portion extending from a body of the preform and wherein the handle is integrally moulded with the body of the preform. 
     Stretch blow moulding die: In this specification, a stretch blow moulding die comprises an openable cavity adapted to receive a preheated preform for subsequent stretch blow moulding of the preheated preform within the cavity of the die. 
     Accordingly in one broad form of the invention there is provided a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine dedicated to the stretch-blow-moulding of containers from non-symmetric injection moulded preforms; the non-symmetric preforms including an integral handle extending from a first junction point to a second junction point on a body of the preform; the body of the preform and the integral handle constituted from the same material. 
     In a further broad form of the invention there is provided a method of controlling paths of grippers of pick and place apparatuses of rotating transfer systems; the rotating transfer systems operating in a continuous non-symmetric preform feed stretch-blow-moulding machine; the paths of the grippers following respective loci of non-symmetrical preforms as preforms are transferred by the rotating transfer systems from a preform pick off position, inserted into and extracted from a preform support mandrel of a preheating stage and inserted into and extracted as a stretch-blow-moulded containers from rotating stretch-blow-moulding dies; the non-symmetrical preforms comprising a body portion and an integral handle extending from the body portion: the method including the step of rotationally mounting each of the pick and place apparatuses on a rotating arm of a respective rotating transfer system. 
     In a further broad form of the invention there is provided a method of transferring a non-symmetric preform between stages of a continuous non-symmetric preform feed rotating stretch-blow-moulding machine; the non-symmetric preform being transformed into a stretch-blow-moulded container by a step of stretching and blowing the non-symmetric preform in a cavity of the stretch-blow-moulding die; the method including the step of orienting the non-symmetrical preform so that an integral handle of the preform has a known orientation at arrival at a pick off position in the machine. 
     In a further broad form of the invention there is provided a method of manipulating, a non-symmetrical injection moulded preform into a stretch-blow-moulding die of a continuous preform feed stretch-blow-moulding machine; the method including the step of extracting a preform from a preform preheating stage with a pick and place apparatus of a continuously rotating transfer system such that an integral handle of the preform has a predetermined orientation. 
     In a further broad form of the invention there is provided a method of controllably heating a pre-form to a die introduction temperature; the pre-form having a neck portion extending from a body portion; said pre-form further having a handle portion extending radially; said method comprising controllably transferring an integral handle PET pre-form onto a continuously moving conveyor; securing the preform by its neck portion to the conveyor whereby the preform is transported by the conveyor at substantially constant velocity along a reheating path from a pre-form entry location to a pre-form exit location. 
     Preferably at least portions of the pre-form controllably heated to the die introduction temperature by the time it reaches the pre-form exit location. 
     Preferably a controllable heater array distributed along the path arranged to direct heat to selected portions of the pre-form. 
     Preferably the pre-form controllably transferred from the preform exit location into a die for stretch blow moulding of the pre-form thereby to form a blown container. 
     In a further broad form of the invention there is provided a method of orienting a non-symmetrical preform for entry to stages of a stretch blow-moulding machine; the none  symmetrical preform including an integral handle extending from a first junction point below a neck of the preform to a second junction point on the body of the preform; the method including the step of providing preforms to slide down inclined rails towards an orientation mechanism while supported by the necks of the preforms along upper rails of the inclined rails. 
     In a further broad form of the invention there is provided a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine in which injection-moulded preforms with integral handles are transferred from a first transfer system to a preheating stage; the transfer of a preform from a gripper of the first transfer system to a preform supporting mandrel achieved in one fluid motion as a vertical axis of the preform is brought into alignment with a vertical axis of the preform supporting mandrel and the handle of the preform is slid into a heat shield provided on the mandrel. 
     Accordingly in further broad form of the invention there is provided a continuous non-symmetric preform feed stretch-blow-moulding machine dedicated to the stretch-blow-moulding of containers from non-symmetric injection moulded preforms; the non-symmetrical preforms including an integral handle extending from a first junction point to a second junction point on a body of the preform; the body of the preform and the integral handle constituted from the same material; the machine including a preform orientation system to orient the handle of the preform into a known orientation at arrival at a pick off position. 
     Preferably the preforms are in continuous motion from an initial preform pick off point through stretch-blow-moulding into the containers and ejection from the machine as stretch-blow-moulded containers. 
     Preferably the integral handle retains a shape of the handle as injection moulded through all stages of the stretch-blow-moulding machine to forming a handle on the stretch-blow-moulded container. 
     Preferably the stages of the stretch-blow-moulding machine include a handle orientation stage; all preforms arriving at the pick off point having the integral handle oriented in a predetermined direction relative to motion of the preform approaching the pick off position. 
     Preferably the stages of the stretch-blow-moulding machine include a continuously rotating first transfer system transferring preforms from a continuously rotating preform feeder wheel at the preform pick off position to a transfer to preheating position at a continuously rotating preheating stage. 
     Preferably a first pick and place apparatus of the first transfer system includes a preform grasping gripper; reciprocating rotation and linear displacement of the grasping gripper induced by a combination of a rotating carrier of the pick and place apparatus and two cam loci. 
     Preferably the rotating carrier is an arm of four radially extending support arms rotating about a common centre of rotation; an outer end of each support arm rotationally supporting a pick and place apparatus. 
     Preferably the support arms rotate above a fixed cam plate; the cam plate provided with an inboard cam channel for a first locus of the two cam loci and a periphery of the cam plate providing an outer cam surface for a second locus of the two cam loci. 
     Preferably a housing of a linear guide of the pick and place apparatus is rotationally mounted at the outer end of the supporting arm; an outrigger arm extending from the housing provided with a first cam follower locating in the cam channel. 
     Preferably a free sliding element of the linear guide is provided with a second cam follower; the second cam follower maintained in contact with the outer cam surface by a spring. 
     Preferably the grasping gripper of the pick and place apparatus is mounted to a rotary actuator supported from an outer end of the free sliding element; the rotary actuator adapted to rotate fingers of the grasping gripper 180 degrees as a pick and place apparatus transits between the preform pick off position and the transfer to preheating position. 
     Preferably the continuously rotating preheating stage includes a preform transport system; preform supporting mandrels travelling along a loop rail system; the preform supporting mandrels rotating preforms about a vertical axis of the preforms as preforms travel past banks of heating elements. 
     Preferably the preform supporting mandrels are provided with a heat shield; the heat shield comprising a channel projecting from a cylindrical collar. 
     Preferably the pick and place apparatus of the first transfer system brings a vertical axis of a perform into alignment with a vertical axis of the cylindrical collar of a preform supporting mandrel at the transfer to preheating position; the gripper of the pick and place apparatus concurrently manoeuvring the handle of the preform between side elements of the channel of the mandrel. 
     Preferably the preform is lowered after the neck of the preform is released by the gripper of the pick and place apparatus so that the neck of the preform is located within the cylindrical collar of the mandrel. 
     Preferably a preheated preform is extracted from a supporting mandrel by a pick and place apparatus of a second transfer system at a transfer from supporting mandrel position; the transfer from supporting mandrel position lying on a line joining respective centres of rotation of a proximate rotating guide wheel of the preheating transport system and the second transfer system. 
     Preferably the preform extracted from a preform supporting handle by a gripper of the pick and place apparatus of the second transfer system is rotated through 180 degrees by a rotary actuator of the pick and place apparatus as an arm of the second transfer system rotates the pick and place apparatus towards a die loading position. 
     Preferably a combination of rotation of the arm of the second transfer system and rotation and linear displacement of the gripper induced by the loci of a first and second cam follower of the pick and place apparatus, brings a vertical axis of the preform into alignment with a vertical axis of a stretch-blow-moulding die as both the pick and place apparatus and an opened stretch-blow-moulding die approach the die loading position; movements of the gripper concurrently bringing the handle of the preform into alignment with a line joining respective centres of rotation of the stretch-blow-moulding die and the second transfer system. 
     Preferably a pick and place apparatus of a third transfer system extracts a stretch-blow-moulded container from the stretch-blow-moulding die as the stretch-blow-moulding die opens at a die unloading position; the die unloading position lying on a line joining respective centres of rotation of the rotating stretch-blow-moulding die and the third transfer system. 
     Preferably the extracted stretch-blow-moulded containers are rotated from the die unloading position to a rotating outfeed wheel; the rotating outfeed wheel transferring the containers along a discharge channel and a container receiving bin. 
     In yet a further broad form of the invention there is provided a pick and place apparatus manipulating a non-symmetrical preform; the pick and place apparatus operating in a continuously rotating stretch-blow-moulding machine wherein a preform gripping gripper of the pick and place apparatus is urged into reciprocating rotation and linear displacement by a combination of a rotating support of the pick and place apparatus and two cam loci. 
     Preferably the reciprocating rotation is about a vertical axis; linear displacement being in a horizontal plane. 
     In yet a further broad form of the invention there is provided a method of controlling paths of grippers of pick and place apparatuses of rotating transfer systems; the rotating transfer systems operating in a continuous non-symmetric preform feed stretch-blow-moulding machine; the paths of the grippers following respective loci of non-symmetrical preforms as preforms are transferred by the rotating transfer systems from a preform pick off position, inserted into and extracted from a preform support mandrel of a preheating stage and inserted into and extracted as a stretch-blow-moulded containers from rotating stretch-blow-moulding dies; the non-symmetrical preforms comprising a body portion and an integral handle extending from the body portion; the method including the steps of:
         rotationally mounting each of the pick and place apparatuses on a rotating arm of a respective rotating transfer system,   urging reciprocating rotation of the grippers about respective vertical axes of the pick and place apparatuses controlled by a locus of a first cam follower and the rotation of the rotation of the rotating arm,   urging reciprocating horizontal linear displacement controlled by a locus of a second cam follower and the rotation of the rotating arm, and,   wherein the locus of the first cam follower is determined by a cam channel of a cam plate; the locus of the second cam follower being determined by an outer cam surface of the cam plate.       

     Preferably a first rotating transfer system transfers a non-symmetrical preform from a rotating preform feeder wheel to a rotating preform support mandrel of the preform preheating system. 
     Preferably a second rotating transfer system transfers a non-symmetrical preform from a rotating perform support mandrel into a stretch-blow-moulding die. 
     Preferably a third rotating transfer system extracts stretch-blow-moulded containers from the stretch-blow-moulding die to a rotating out feed wheel. 
     In yet a further broad form of the invention there is provided a method of transferring a non-symmetric preform between stages of a continuous non-symmetric preform feed rotating stretch-blow-moulding machine; the non-symmetric preform being transformed into a stretch-blow-moulded container by a step of stretching and blowing the non-symmetric preform in a cavity of the stretch-blow-moulding die; the method including the steps of:
         orienting the non-symmetrical preform so that an integral handle of the preform has a known orientation at arrival at a pick off position in the machine,   gripping a neck of the preform in grippers of a pick and place apparatus of a rotating first rotating transfer system and rotating the preform to a preheating stage of the machine,   manoeuvring the gripper of the first pick and place apparatus so as to align the integral handle with a heat shield of a moving preform supporting mandrel and aligning an axis of a body of the preform with a neck supporting cylindrical collar of the mandrel,   removing the non-symmetric preform from the preform supporting mandrel with a gripper of a second pick and place apparatus of a rotating second rotating transfer system and rotating the preform to a rotating stretch-blow-moulding die of the machine in a second stage,   manoeuvring the gripper of the second pick and place apparatus so as to align the integral handle with a handle nesting portion of the stretch-blow-moulding die and a vertical axis of the preform with a vertical axis of the stretch-blow-moulding die in a third stage,   manoeuvring grippers of a pick and place apparatus of a rotating third rotating transfer system in position to grasp the neck of a now stretch-blow-moulded container and extracting the stretch-blow-moulded container from the stretch-blow-moulding die in a fourth stage.       

     Preferably the movement of the grippers of the pick and place apparatus of any one of the first, second or third rotating transfer systems is controlled by a combination of rotation of an arm of the transfer system supporting the pick and place apparatus and rotation and linear displacement controlled by loci of two cam followers. 
     Preferably the locus of the first cam follower is determined by a cam channel provided in a fixed cam plate of each of the first, second and third rotating transfer systems; the locus of the second cam follower determined by an outer cam surface of the fixed cam plates. 
     In yet a further broad form of the invention there is provided a method of manipulating a non-symmetrical injection moulded preform into a stretch-blow-moulding die of a continuous preform feed stretch-blow-moulding machine; the method including the steps of:
         extracting a preform from a preform preheating stage with a pick and place apparatus of a continuously rotating transfer system such that an integral handle of the preform has a predetermined orientation, and   wherein manoeuvring of a preform supporting gripper of the pick and place apparatus is controlled by rotation of an arm of the transfer system in combination with rotation and linear extension of the gripper guided by loci of two cam followers.       

     Preferably the method includes the further steps of:
         manoeuvring the pick and place apparatus to align the integral handle with a bisecting radial line of an open stretch-blow-moulding die as the bisecting radial line rotates into coincidence with a line extending between rotation centres of the stretch-blow-moulding machine and the transfer system,   further manoeuvring the pick and place apparatus to align a vertical axis of a body of the preform with an axis of the die and the handle of the preform with a handle nesting portion of the die when opposing halves of the die close on reaching the line between rotation centres,       

     In yet a further broad form of the invention there is provided a method of preventing distortion of an integral handle of a preform in a stretch-blow-moulding process in a continuous preform feed stretch-blow-moulding machine; the method including the steps of:
         preparing each half of a stretch-blow-moulding die with a handle nesting cavity conforming to at least a portion of the integral handle of the preform,   manipulating the preform so that the handle is brought into coincidence with the handle nesting cavity as two halves of the stretch-blow-moulding die close on the preform.       

     Preferably the manipulation of the preform is by a pick and place apparatus; a gripper of the pick and place apparatus urged into rotational and linear motion by a combination of rotation of an arm of a preform transfer system to which the pick and place is mounted, and rotation and linear displacement controlled by two cam loci. 
     In yet a further broad form of the invention there is provided a method of controllably heating a pre-form to a die introduction temperature; the pre-form having a neck portion extending front a body portion; said pre-form further having a handle portion extending radially; said method comprising
         controllably transferring an integral handle PET pre-form onto a continuously moving conveyor;   securing the preform by its neck portion to the conveyor whereby the preform is transported by the conveyor at substantially constant velocity along a reheating path from a pre-form entry location to a pre-form exit location;   least portions of the pre-form controllably heated to the die introduction temperature by the time it reaches the pre-form exit location;   a controllable heater array distributed along the path arranged to direct heat to selected portions of the pre-form;   the pre-form controllably transferred from the preform exit location into a die for stretch blow moulding of the pre-form thereby to form a blown container.       

     Preferably the handle portion is solid and has a first end and a second end; the first end integrally connected at a first, upper location to the pre-form; the second end integrally connected at a second, lower location to the pre-form. 
     Preferably the first, upper location is located on the body portion. 
     Preferably the first, upper location is located on the neck portion. 
     Preferably the second, lower location is located on the body portion. 
     Preferably the elements are arranged in modules; the modules arrayed around the continuously rotating preform conveyer; the elements controlled as a group based on height wherein the top most elements of the modules are controlled to a predetermined temperature together whilst the next down in height elements are also controlled together to a predetermined temperature—and so on down to elements at the lowest level. 
     Preferably a processor controls the speed of rotation of a motor in order to control the continuous speed of advancement of the preforms. 
     Preferably a temperature sensor provides environment temperature sensing which is utilised by processor to modulate the degree of heating of all elements by a difference factor delta (Δ). 
     In yet a further broad form of the invention there is provided an orientation mechanism controlling orientation of a non-symmetric injection moulded preforms prior to entry into stages of a stretch blow-moulding machine; the non-symmetric preforms each including an integral handle extending from a first junction point below a neck of the preform and a second junction point on a body of the preform; the mechanism including a pair of contra-rotating drive wheels disposed along opposite sides of inclined rails; one of the drive wheels inducing rotation of the body of the preform moving down the inclined rails to rotate the handle of the preform into a preferred position. 
     Preferably the inclined rails include a pair of upper rails between the preforms are suspended by necks of the preform and a pair of lower rails which constrain the integral handles into approximate alignment with a long axis of the inclined rails; integral handles of the preforms constrained to either a leading or a trailing orientation. 
     Preferably the pair of drive wheels are located at a level coincident with a lower portion of the body of the preform below the lower rails and a lowest point of the integral handles; axes of the drive wheels normal to the long axis of the inclined rails. 
     Preferably a gap between the pair of drive wheels is smaller than a diameter of the body of the preform; each guide wheel including at least one tyre of a sufficiently soft polymer material to allow passage of the body of the preform through the gap between the pair of drive wheels. 
     Preferably directions of rotation of the pair of contra-rotating drive wheels draw preforms moving down the inclined rails through the gap between the drive wheels; a first of the drive wheels rotating in an anticlockwise direction with a second opposite drive wheel rotating in a clockwise direction. 
     Preferably the drive wheels rotate at different rates of rotation; the ratio of rotation of the first drive wheel to the rotation of the second opposite drive wheel being of the order of 2:1. 
     Preferably the different rates of rotation of the drive wheels cause the second opposite drive wheel to rotate the body of the preform in an anticlockwise direction as the preform passes through the gap between the two drive wheels. 
     Preferably rotation of the body of the preform changes orientation of a preform with a leading handle at entry to the mechanism to a preform with a trailing handle on exit from the mechanism; a gap in the lower rail at the side of the lower rail adjacent the first drive wheel. 
     In yet a further broad form of the invention there is provided a method of orienting a non-symmetrical preform for entry to stages of a stretch blow-moulding machine; the none symmetrical preform including an integral handle extending from a first junction point below a neck of the preform to a second junction point on the body of the preform; the method including the steps of:
         providing preforms to slide down inclined rails towards an orientation mechanism while supported by the necks of the preforms along upper rails of the inclined rails,   constraining integral handles of the preforms in either a leading or in a trailing position between lower rails of the inclined rails,   drawing preforms through a gap between a pair of contra rotating drive wheels of the orientation mechanism disposed along the inclined rails, and   wherein differential rates of rotation of the pair of drive wheels rotate the body of the preform from a leading orientation of the integral handle at entry to the orientation mechanism into trailing orientation of the handle at exit of the preform from the orientation mechanism.       

     Preferably the pair of drive wheels are located coincident with a lowermost portion of the body of the preform below lower rails of the inclined rails and below a lowermost point of the integral handle. 
     Preferably a first of the pair of contra rotating guide wheels at one side of the inclined rails rotates in an anticlockwise direction; the second of the pair of contra rotating drive wheels at an opposite side of the inclined rails rotating in a clockwise direction; the pair of contra rotating drive wheels acting to draw preforms through the gap between the drive wheels. 
     Preferably the ratio of the rate of rotation of the contra rotating drive wheel to the rate of rotation of the clockwise rotating drive wheel is in the order of 2:1. 
     Preferably the clockwise rotation of the clockwise rotating drive wheel rotates bodies of a preforms passing through the gap between the drive wheels in an anticlockwise direction such that a preform with an integral handle in a leading orientation is rotated so that the integral handle is in a trailing orientation. 
     In another broad form of the invention, there is provided an injection-moulded preform forming a stretch-blow-moulded container; the preform comprising an open neck portion and a hollow body extending from the neck portion; the preform further including an integrally injection-moulded handle; at least a portion of walls of the hollow body varying in thicknesses. 
     Preferably, at least a portion of an inner surface of the allow body is non-concentric with outer surfaces of the hollow body. 
     Preferably, the outer surfaces or the hollow body are defined by diameters centred on a central longitudinal axis of the preform to form a substantially cylindrical body. 
     Preferably, the cross sections of the at least a portion of the inner surface of the hollow body are ovoid in section. 
     Preferably, the centres of the cross sections of ovoid shape are centred on the central longitudinal axis of the preform. 
     Preferably, the centres of the cross sections of ovoid shaper are offset front the longitudinal axes of the preform. 
     Preferably, the centres of circular cross sections of a portion of the hollow body are offset from a central longitudinal axis of the hollow body. 
     Preferably, a core or mandrel forming the inner surface of the hollow body in an injection moulding step, comprises at least one portion of circular cross sections to form an upper region of the inner surface of the preform portion of the mandrel comprising ovoid cross sections depending from a transition portion between a lower end of the at least one portion of circular cross sections and the portion of ovoid cross sections. 
     Preferably, the mandrel comprises two portions of circular cross sections; an upper portion and a lower portion; the transition portion depending from the lower portion. 
     Preferably, the upper portion is of diameters equal to inner diameters of the neck portion of the preform. 
     Preferably, the lower portion is of diameters smaller than the diameters of the upper portion. 
     Preferably, the transition portion forms an asymmetrical frustum of a cone; an upper end of the transition portion having a diameter equal to that of a lower end of the lower portion with the lower end of the transition portion conforming in cross section to the ovoid cross section of an upper end of the ovoid portion. 
     Preferably, each of the upper portions and the ovoid portion are tapering; the cross sections decreasing in area from respective maximum areas at upper ends of the portions to minimum areas at the respective lower ends. 
     Preferably, the diameters defining the outer surface of the hollow body decrease in dimension from a maximum diameter at a lower end of the neck portion to the lower end of the hollow body. 
     Preferably, the preform includes an integral handle; the handle forming a loop of material extending vertically below the neck portion of the preform to a lower junction on the body of the preform. 
     Preferably, a central vertical plane of the handle passes through the central axis of the preform. 
     Preferably, the major axes of the cross sections of the ovoid portion of inner surface of the hollow body of the preform lie in the central vertical plane. 
     Preferably, the wall thicknesses of the preform in that portion of the preform in which the inner surfaces are defined by the ovoid cross sections, vary from a maximum at opposite ends of the minor axes of the ovoid cross sections to minimum thicknesses at outer ends of the major axes. 
     Preferably, the ratio of maximum wall thickness to minimum wall thickness of the ovoid portion lies in the range of 2:1 and 2.2:1. 
     Preferably, the polymer walls of the preform proximate maximum thickness are distributed predominantly to longer side walls of a rectangular cross section blown container; the polymer walls of the preform proximate minimum thickness predominantly distributed to shorter side walls of the blown container. 
     In another broad form of the invention, there is provided a method of optimizing wall thickness in a stretch-blow-moulded container; the method including the steps of:
         injection moulding hollow preforms in which at least a lower portion of each preform has internal cross sections non-concentric with external surfaces of the lower portion,   bringing the preforms to a temperature suitable for stretch-blow-moulding,   inserting the preforms into cavities of a stretch-blow-moulding machine,   mechanically stretching the preforms and injecting air to form the container.       

     Preferably, the mandrels for the injection moulding of the preforms include at least one upper region of circular cross sections. 
     Preferably, the lower portion of the preform has cross sections of an ovoid form. 
     Preferably, the upper region of the mandrel includes an upper portion and a lower portion. 
     Preferably, a transition portion extends between a lower end of the lower portion and an upper end of the lower section. 
     Preferably, the external surfaces of the preform are defined by diameters centred on a central longitudinal axis of the preform. 
     Preferably, an integral handle is formed on the preform extending in a loop between a first junction region below a neck portion of the preform and a second junction region on a body of the preform; a central vertical plane of the integral handle coincident with the central longitudinal axis. 
     Preferably, the major axes of the cross sections of ovoid form of the lower section lie in the central vertical plane. 
     Preferably, the wall thicknesses of the preform in the lower section vary from maximum thicknesses at opposite ends of the minor axes of the ovoid cross sections to minimum thicknesses at opposite ends of the major axes. 
     Preferably, in stretch-blow-moulding a container of generally rectangular cross section, polymer material proximate the maximum thicknesses is distributed to longer sides of the container and polymer material proximate the minimum thicknesses is distributed to shorter sides of the container. 
     In another broad form of the invention, there is provided a mandrel for forming internal surfaces of an injection-moulded hollow preform; the mandrel including at least one portion with cross sections which are non-concentric with diameters defining outer surfaces of the preform. 
     Preferably, the non-concentric cross sections are ovoid in form; the ovoid forms defining varying wall thickness of the preform. 
     Preferably, the major axes of the ovoid formed cross sections lie in a vertical plane containing a vertical central longitudinal axis of the preform; the vertical plane forming a mid plane of an integral handle formed on the preform depending vertically from a first junction region below a neck portion of the preform to a second junction point on a body of the preform. 
     In another broad form of the invention, there is provided a method of biasing distribution of polymer material from walls of at least one portion of a preform to selected side walls of a container stretch-blow-moulded from the preform the method including to steps of:
         arranging a mandrel defining inside surfaces of the preform with cross sections of the at least one portion which are non-concentric with corresponding outer surfaces of the preform as defined by a cavity of a preform injection moulding die,   arranging the mandrel in the injection moulding die such that major axes of the cross sections of the mandrel of the at least one portion are aligned with a central vertical plane of the cavity,   injection moulding the preform,   introducing the preform into a cavity or a stretch-blow-moulding machine such that the central vertical plane of the preform is aligned with a central vertical plane of a blown container of generally rectangular cross section, and   wherein the central vertical plane of the container is parallel to opposing longer sides of the container.       

     Preferably, the cross sections of the mandrel in the at least one portion are ovoid in shape; major axes of the ovoid cross sections aligned with the central vertical plane; centres of the ovoid cross sections coincident with a central axis of a body of the preform. 
     Preferably, the outer surfaces of the body of the preform are defined by diameters centred on the central axis. 
     Preferably, the preform includes an integral handle forming an integral handle on the container; the integral handle of the preform extending vertically from a first junction below a neck portion of the preform to a second junction on a body of the preform; the integral handle centred on the central vertical plane of the preform. 
     Preferably, in a blow moulding stage polymer material of walls of the preform in the at least one portion and on opposing ends of a minor axes of the ovoid cross sections are biased to the opposing longer sides of the container; polymer material proximate to opposite ends of a major axes of the ovoid cross sections biased towards the shorter side walls of the container. 
     In another broad form of the invention, there is provided a method of injection moulding a preform in which at least a portion of wall thicknesses of a hollow body of the preform varies along a length of the hollow body; the method including the steps of;
         forming at least one pair of opposing cavities in an injection moulding die; the cavities defining external surfaces of the preform and an integral handle,   locating a mandrel in each of the at least one opposing cavities such that a central longitudinal axis of the mandrel is coincident with an axis of the cavity as defined by a neck portion of the hollow body,   closing the injection moulding die to form a cavity about the mandrel,   injecting a polymer into the cavity to form the preform, and   wherein the injection-moulded preform includes an integral, injection-moulded handle; the handle extending as a loop from a first junction point below a neck portion of the preform to a second junction point on the hollow body of the preform.       

     Preferably, the wall thicknesses of the hollow body of the perform increase from below the neck portion to proximate a lower end of the preform. 
     Preferably, the cross sections of internal surfaces of the perform are concentric with cross sections of external surfaces of the preform. 
     Preferably, at least a portion of cross sections of internal surfaces of the preform are non-concentric with cross sections of outer surfaces of the preform. 
     Preferably, the non-concentricity of the cross sections of internal surfaces of the preform with cross sections of the outer surface of the preform is from a portion of cross sections of the internal surface being of ovoid form. 
     Preferably, the non-concentricity of the internal surfaces with the outer surface of the hollow body is from centres of cross sections of the internal surface being of offset from a central longitudinal axis of the preform. 
     In a further broad form of the invention, there is provided a preform and a container stretch-blow-moulded from the preform in a stretch-blow moulding machine; the preform comprising a neck portion, a collar below the neck portion and a body extending from below the collar; the body including a first cylindrical portion having a first diameter and a second conical portion tapering from a diameter smaller than the diameter of the first portion to a minimum diameter proximate a bottom portion of the preform. 
     Preferably, the preform includes an integral handle forming a loop extending from a first junction position proximate the collar to a second junction position along the body. 
     Preferably, the first cylindrical portion extends from below the collar; the first portion being of a substantially constant diameter. 
     Preferably, wall thickness of the second conical portion tapers from a minimum thickness proximate the first cylindrical portion to a maximum thickness proximate a tangent line between the conical portion and a bottom portion of the preform. 
     In a further broad form of the invention, there is provided a method of reducing material required to form a container stretch-blow-moulded from a preform; the preform comprising a neck portion, a collar below the neck portion and a generally cylindrical body below the neck portion; the preform further including a handle extending from a first junction position below the collar to a second junction position alone the body of the preform; the method including the steps of:
         Forming the body of the preform in at least two portions of different configuration; a first cylindrical portion and a second conical portion;   Reducing a base diameter of the conical portion relative to a diameter of the first cylindrical portion.       

     Preferably, wall thickness of the second portion varies from a minimum thickness proximate the base diameter of the conical portion to a maximum thickness proximate a tangent line between the second conical portion and a bottom portion of the preform. 
     In a further broad form of the invention, there is provided a continuously rotating stretch-blow-moulding machine the stretch-blow-moulding machine including an orientation device orienting integral handles of injection-moulded preforms from which containers with integral handles are stretch-blow-moulded is the machine; the orientation device including a pair of side by side contra-rotating auger screws located above spaced apart main support rails of a preform infeed track and centred about a vertical mid plane of the main support rails; configuration of diameters, pitch and flutes of the auger screws arranged to capture necks of the preforms and advance preforms along the preform infeed track; sides of preforms advancing along the auger screws contacting a friction strip inducing rotation of the preforms; rotation causing all preform integral handles to rotate from any random first orientation to a second predefined orientation. 
     Preferably, the preforms with integral handles are fed onto a pair of side by side contra-rotating rollers centred about the vertical mid plane of the pair of spaced apart rails of the preform feed-in track; the pair of contra-rotating rollers located before the auger screws; the pair of roller space apart sufficient to allow bodies and integral handles of the preforms to slide between the rollers into a position wherein the preforms are suspended between the rollers by collars below the necks of the preforms; the bodies and integral handles of the preforms constrained between spaced apart guide rails in the random first orientation; the guide rails located at a level below the main preform support rails proximate the middle of the handles. 
     Preferably, in the random first orientation handles may be leading or trailing relative a direction of movement of preforms along the infeed track towards a preform pick-off position at a lower outer end of the infeed track. 
     Preferably, the friction strip mounted to one of the main support rails is substantially coextensive with lengths of the auger screws; the friction strip intruding into space between the pair of spaced apart main support rails sufficient to engage with the sides of bodies of preforms moved along by the auger screws. 
     Preferably, a section of that guide rail on the same side as the friction strip is discontinuous for a length substantially coextensive with lengths of the auger screws. 
     Preferably, rotation of the preforms while carried along the auger screws rotates all preform handles into a handle trailing position with the handles arrested by contact with that guide rail of the pairs of guide rails opposite to the friction strip; the handles able to rotated through the discontinuous section of the guide rail. 
     Preferably, the auger screws separate successive preforms according to the pitch of the auger screws; the auger screws further providing downward pressure on preforms with oriented handles between the ends of the auger screws and the preform pick-off position. 
     In a further broad form of the invention, there is provided a method of producing stretch-blow-moulded containers with integral handle in a continuously rotating stretch-blow-moulding machine; the containers with integral handle stretch-blow-moulded from separately injection-moulded preforms with integral handle; the preform comprising a neck portion, a body portion and a handle funning a loop of orientable material extending from a first junction point below the neck portion to a second junction point on the body portion; the method of injection-moulding including the steps of:
         Forming a multicavity injection-moulding die;   In a heated fixed side of the die forming an array of cavities; the cavities formed to correspond to sections of the preforms to a point below the integral handle;   Providing a corresponding array of opposing half cavities projecting from a face of the opposite moving side of the die; the half cavities shaped to form the preform from the neck portion, body and integral handle to the point below the integral handle;   Providing cores for forming the internal shape of the preforms; the cores fixed to the moving side of the die and centred on a common axis of the cavities in the fixed heated side of the die and the opposing half cavities.       

     Preferably, in a mould cycle
         cavities in the heated fixed side of the die and the opposing half cavities at the opposite moving side of the die are injected with orientable polymer material to form the preforms;   When filled, after a predetermined delay moving the moving side of the die away from the heated fixed side to draw the ends of the preform bodies below the handle out of the cavities in the heated fixed side of the die;   After a predetermined delay, opening the opposing half cavities to release the neck portion, the integral handle and the body portion of the preform to below the handle portion.       

     Preferably, further in the mould cycle
         activating a robot to position an array of vacuum suction elements between the heated fixed side of the die and the moving side of the die;   positioning the array of vacuum suction elements in registration with the array of cavities;   as the opposing half cavities open apply vacuum pressure to the vacuum elements and activate the robot to drive the vacuum elements to fit over the ends of the preforms;   retract the robot to draw the preforms from the cores and withdraw the vacuum elements and retained preforms from between the heated fixed side and the moving side of the die;   rotate the array of vacuum elements into a position in which axes of the preforms are substantially vertical and cut vacuum pressure to allow preforms to fall into a receiving bin.       

     Preferably, each vacuum element is provided with a slot or channel at an open end of the vacuum elements; the slot or channel provided to allow each vacuum element to accommodate at least a portion of the handle of the preform. 
     In a further broad form of the invention, there is provided a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine in which injection-moulded preforms with integral handles are transferred from a first transfer system to a preheating stage; the transfer of a preform from a gripper of the first transfer system to a preform supporting mandrel achieved in one fluid motion as a vertical axis of the preform is brought into alignment with a vertical axis of the preform supporting mandrel and the handle of the preform is slid into a heat shield provided on the mandrel, the transfer made while accommodating each of the rotations of a loop rail of the preheating stage, the mandrel and the transfer system as well as movements of the gripper. 
     Preferably, the handle as injection moulded is protected by the heat shield during the preheating stage; the shape of the handle of a container stretch-blow-moulded from the injection moulded preform being identical to the as injection-moulded shape of the handle of the preform. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Embodiments of the present invention will now be described with reference to the accompanying drawings wherein: 
         FIG.  1    is a side view of a perform with integral handle for stretch blow-moulding a container by means of a continuous blow moulding machine; 
         FIG.  2    is a side view of a container with integral handle stretch blow-moulded from the preform of  FIG.  1   ; 
         FIG.  3    is a plan view of the stretch blow-moulding machine producing the container of  FIG.  2   ; 
         FIG.  4    is a side view of a preform orientation and loading section of the machine of  FIG.  3   ; 
         FIG.  4 A  is a plan view of the preform orientation and loading section of the machine of  FIG.  3   ; 
         FIG.  4 B  is a plan view of a further preferred embodiment of a preform orientation arrangement for the machine of  FIG.  3   ; 
         FIG.  4 C  is a side elevation view of the orientation arrangement of  FIG.  4 B ; 
         FIG.  4 D  is a perspective view from below of the orientation arrangement of  FIGS.  4 B and  4 C ; 
         FIG.  5    is a plan view of a loading end of the preform orientation and loading section of  FIG.  4    and a first preform transfer system; 
         FIG.  6    is a perspective view of the first preform transfer system of  FIG.  5   ; 
         FIG.  7    is a plan view of a portion of the preform transfer system of  FIGS.  5  and  6    and a preform loading and unloading area of a preform preheating stage of the machine; 
         FIG.  8    is a perspective view of a perform of  FIG.  1    inserted into a mandrel with heat shield far transport through the preform preheating stage of the machine; 
         FIG.  9    is an enlarged plan view of section of the machine showing a portion of the preform loading and unloading area of  FIG.  7   , a second transfer system and a portion of the stretch-blow-moulding dies assembly of the machine; 
         FIG.  10    is a front view of one half of a stretch-blow-moulding die for the production of the container shown in  FIG.  2   ; 
         FIG.  11    is a plan view of a portion of the machine of  FIG.  3    showing the region of transfer of blown containers from a stretch-blow-moulding die to a container receiving bin; 
         FIG.  12    is a schematic block diagram of control components associated with control of the heating and transport of the preforms usable with any of the above described embodiments; 
         FIG.  13    is a side view of typical injection-moulded preform for stretch-blow-moulding of a polymer container. 
         FIG.  13 A  is a sectioned side view of a preform according to a preferred embodiment of the invention in which a central vertical plane passing through a central vertical axis of the preform lies in the plane of the paper, 
         FIG.  14    is a side view of a mandrel for injection-moulding the preform of  FIG.  13 A  in which a central vertical plane passing through a central vertical axis of the mandrel lies in the plane of the paper; 
         FIG.  15    is cross section along the vertical central axis of the mandrel of  FIG.  14    taken at the level of A-A; 
         FIG.  16    is a cross section along the vertical central axis of the mandrel of  FIG.  3    taken at the level B-B; 
         FIG.  17    is a side view of a container stretch-blow-moulded from the preform of  FIG.  2   ; 
         FIG.  18    is an end view of the container of  FIG.  17   ; 
         FIG.  19    is a sectioned side view of a further preferred embodiment of a preform according to the invention; 
         FIGS.  19 A and  19 B  are selected cross sections the preform of  FIG.  19   ; 
         FIG.  20    is a sectioned side view of a further preferred embodiment of a preform according to the invention; 
         FIGS.  20 A and  20 B  are selected cross sections of the preform of  FIG.  20   ; 
         FIG.  21    is a sectioned side view of a further preferred embodiment of a preform according to the invention; 
         FIGS.  21 A and  21 B  are selected cross sections of the preform of  FIG.  21   ; 
         FIG.  22    is a sectioned side view of a further preferred embodiment of a preform according to the invention; 
         FIGS.  22 A and  22 B  are selected cross sections of the preform of  FIG.  22   ; 
         FIG.  23    is a sectioned side view of a further preferred embodiment of a preform according to the invention; 
         FIGS.  23 A and  23 B  are selected cross sections of the preform of  FIG.  23   ; 
         FIG.  24    is a schematic view of an injection moulding process for producing the preforms of  FIGS.  13 A and  19 ,  20  to  23   ; 
         FIG.  25    is a container with integral handle as blow-moulded from the preform of  FIG.  13   , 
         FIG.  26    is a preform of reduced PET volume according to a preferred embodiment of the invention, 
         FIG.  27    is a cross section view of the body of the preform of  FIG.  26    showing variations in wall thickness, 
         FIG.  28    is a side view of a container stretch-blow-moulded from the preform of  FIGS.  26  and  27   , 
         FIG.  29    is a further side view of a preform with integrally formed handle according for stretch-blow-moulding in the machine of the invention, 
         FIG.  30    is a sectioned, schematic side view of an injection moulding press and injection moulding die for moulding the preforms for use in the continuous rotating stretch-blow-moulding machine of the invention, with the die opened prior to an injection moulding cycle, 
         FIG.  31    is a front view of the face of the moving die section of the injection moulding die of  FIG.  30    at the end of an injection moulding cycle (with the heated fixed die section removed) 
         FIG.  32    is a further view of a part of the injection moulding press showing extraction of moulded preforms by vacuum elements inserted into the opened die by a robot. 
         FIG.  33    is a side view of a preferred embodiment of a preform and integrally attached handle according to the invention. 
         FIG.  34    is an end view of the preform of  FIG.  33   . 
         FIG.  35    is a view from above of the preform and handle of  FIGS.  33  and  34   . 
         FIG.  36    is a sectioned side view of a further preferred embodiment of a preform according to the invention; 
         FIGS.  36 A and  36 B  are selected cross sections of the preform of  FIG.  36   ; 
         FIG.  37    is a sectioned side view of a further preferred embodiment of a preform according to the invention; 
         FIGS.  37 A and  37 B  are selected cross sections of the preform of  FIG.  37   . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A feature of the present machine  10 , a preferred configuration of which is shown in  FIG.  3   , is that motion through the machine of a non-symmetric injection moulded preform  12  as shown in  FIG.  1   , from its initial intake to its emergence as a stretch blow-moulded container  14  (as shown in  FIG.  2   ), is continuous. As shown in  FIG.  1   , the previously injection moulded polymer preform comprises a cylindrical elongate body  16  and neck  18 . An integral handle  20  extends from a first junction point  22  just below the neck  18  to a second junction point  24  on the body  16  of the preform. 
     Referring again to  FIG.  3   , the continuous, non-incrementing process of the machine  10  includes the transfer of preforms from a loading or pick off position  26  to a preheating stage  28 , through the preheating stage and transfer to a stretch-blow moulding die  30  with subsequent removal of the blown container  14  from the die and removal from the machine. These stages will now be described in detail. 
     Entry of Preforms and Handle Orientation—First Preferred Embodiment 
     As shown in the preferred layout of the machine  10  in  FIG.  3    and referring also to  FIGS.  4  and  5   , the previously injection moulded preforms  12  (as shown in  FIG.  1   ) are fed, for example from a hopper (not shown but as well understood in the industry) to slide under gravity down inclined rails  32  while supported by their necks  18 . The inclined rails  32  comprise a pair of upper rails  32   a  between which the preforms are suspended by their necks  18 , and a pair of lower rails  32   b  which constrain the handles  20  of the preforms approximately in line with the long axis of the rails. For reasons that will become clear, it is essential however, that during the passage of preforms through the stages of the machine, the orientation of the integral handle  21  of the preform is controlled precisely. 
     Preforms  12  with a handle roughly oriented pass one by one through an escapement  34  to be captured by a continuously rotating feeder wheel  36  which carries the preform between the feeder wheel and a short rail  40 , in such a way that friction between the body  16  of the preform and the rail  40  induces rotation of the preform and its handle. The rotating handle collides with a stop  40   a  under the rail  40  forcing each handle into a rearward orientation with respect to the direction of travel, to arrive at a pick off position  26 . 
     At the instance that a preform arrives at the pick of position  26 , a pair of opposing actuators (not shown) located under the pick off position  26  simultaneously briefly close on, and then release, the preform handle  20  to fix its orientation relative the gripper  58  which, also at that instant engages with the neck  18  of the preform. 
     Entry of Preforms and Handle Orientation—Second Preferred Embodiment 
     In this second preferred embodiment, with reference now to  FIG.  4 A , the injection moulded preforms  12  are again fed onto inclined rails  32   a,  down which they slide under gravity supported by the flanges at the necks  18 . Again, as described for the first preferred embodiment above, the handles are loosely constrained between lower rails  32   b , with the handles either in a “leading”, that is pointing in the direction of movement of the preforms as they progress down the incline, or “trailing”, pointing rearwardly. 
     In this second preferred embodiment an orientation mechanism  34 A is located at a point along the rails  32  approaching the lower end of the rails. As can be seen in  FIG.  4 A , the mechanism includes two contra-rotating drive wheels  33  and  35 , arranged at opposite sides of the rails  32 , at a level coincident with the lowermost portion of the bodies of the preforms and below the lower rails  32   b  and the lowermost point of the handles. The axes of the wheels are normal to the slope of the inclined rails. Note only the lower rails  32   b  are shown in  FIG.  4 A . 
     The drive wheels  33  and  35  are separated by a gap  37  which is somewhat narrower than the diameter of the body  16  of the preforms. Each of the wheels  33  and  35  is provided with one or two tyres  39  of a sufficiently soft polymer material to allow a preform body  16  to pass through the gap but providing a degree of grip on the body. 
     As shown in  FIG.  4 A , drive wheel  33  rotates in an anticlockwise direction while drive wheel  35  rotates in a clockwise direction. The combination of these two rotations has the effect of drawing a preform through the gap  37 . The two drive wheels do not however rotate at the same rate, with, in the preferred arrangement shown in  FIG.  4 A , drive wheel  35  rotating at a significantly lower rpm than that of guide wheel  33 . A preferred ratio of rotation of drive wheel  33  to drive wheel  35  is of the order of 2:1. 
     The effect of this differential in rate of rotation of the two drive wheels is that drive wheel  35  exerts a considerably greater grip on the body  16  of the preform so that it acts to rotate the preform in an anticlockwise direction as the preform passes through the gap  37  between the two drive wheels. By this means a handle  20  of a preform which is in a leading position as the preform enters the gap  37 , is rotated until it contacts the right hand lower rail  32   b  (as seen from above in  FIG.  4 A ). To allow for this rotation of the handle a gap  40  is provide in the left hand lower rail. 
     It will be understood that the anticlockwise rotation induced by drive wheel  35  has no effect on those preforms entering the gap with their handles trailing, except to drive the trailing handle into contact with the right hand lower rail. Thus, all preforms downstream of the orientation mechanism  34 A approach the escapement  34  in the preferred orientation with the handles in the trailing position. 
     The escapement  34  controls the feeding of the handle oriented preforms to the feeder wheel  36  as described above, retaining the trailing orientation of the handles as induced by the mechanism  34 A. As for the first arrangement above, at the instance that a preform arrives at the pick of position  26 , a pair of opposing actuators (not shown) located under the pick off position  26 , simultaneously briefly close on, and then release, the preform handle  20  to fix its orientation relative the gripper  58  which, also at that instant engages with the neck  18  of the preform. 
     It will be understood that although the above description is specific to the rotation of the preform in an anticlockwise direction by the clockwise rotating drive wheel, orientation according to the principles of the mechanism may equally be achieved by reversing the differential rates of rotation of the two drive wheels and providing the gap in the lower guide rail on the opposite side to that illustrated in  FIG.  4 A . In this alternative arrangement, it is then the anticlockwise rotating drive wheel which induces clockwise rotation to the body of a preform passing between the wheels, rotating a leading oriented handle until it contacts the left hand lower rail (as seen from above in  FIG.  4 A ), the gap allowing rotation of the handle then being provided in the right hand lower rail. 
     Precise orientation of the handle throughout the stages of the machine is critical to the process of preheating where the orientation must align with the alignment of beat shields, and for correctly placing the preform and the handle into the stretch-blow-moulding die. 
     Entry of Preforms and Handle Orientation—Third Preferred Embodiment 
     With reference now to  FIGS.  4 B to  4 D , in this further preferred arrangement of a handle orientation mechanism  34   b,  injection moulded preforms  12  emerge one at a time from a bulk supply via, for example, a conveyor (not shown) to be deposited centrally onto a pair of contra-rotating, downward sloping rollers  11  and  13 . The rollers  11  and  13  are so spaced as to allow the body  16  and handle  20  of each preform to drop through the gap between them but retain the wider diameter of the projecting collar below the neck  18  of the preform. The rollers  11  and  13  are mounted above a pair of spaced apart guide rails  15  and  17  (as best seen in  FIG.  4 D ) similarly spaced as the gap between the rollers. As the bodies and the handles of the preforms drop through the gap between the rollers and that between the guide rails  15  and  17 , the handles  20  are constrained into approximate alignment between these rails, but at this stage handles may be “leading” or “trailing” relative to movement in the downward direction shown in  FIGS.  4 C and  4 D . Since it is a requirement imposed by the design of the blow-moulding machine described below, that preform handles at entry of preforms into the feeder wheel  36  must be in the trailing position, those leading must be turned around. 
     At the downward ends of the rollers, the preforms drop to the level of support rails  19  and  21 , so that preforms are now retained between these main support rails by their collars. A combination of gravity and pressure from following preforms forces each preform against the upward outer ends of side by side, contra-rotating auger screws  23  and  25  located on either side of a median vertical plane between the support rails. The flutes  27  of the auger screws are sized so as to capture between them the necks  18  of the preforms. The pitch of the auger screws is such as to separate preforms while being driven in the downward direction by the screws&#39; rotation. 
     Generally coextensive with the length of one of the auger screws, (in the arrangement shown in the drawings, auger screw  25 ), the main support rail  21  is provided at its underside with a friction strip  29  (as best seen in the enlargement inset of  FIG.  4 D ). This friction strip  29  projects slightly into the gap between the main support rails  19  and  21  so that its inner edge engages with the body of a preform as it progresses between the augers. This friction contact urges rotation of the preform in an anticlockwise direction as seen from above. 
     Also approximately coextensive with the length of the auger screw  25  is a gap in the guide rail  17 . Any rotation of an already trailing handle, will only force the handle into engagement with the opposite guide rail  15 , and remain trailing. But, as can be seen from the enlarged inset of  FIG.  4 D , handles of preforms with handles leading at entry between the auger screws will gradually be rotated from the position where the handle is leading to it being in the trailing position, (being free to do so by the gap in guide rail  17 ) until these handles also are arrested from further rotation by the opposite guide rail  15 . From here as can be seen from  FIGS.  4 C and  4 D , the preforms, all with handles trailing, proceed down the main support rails  19  and  21  with the handles constrained between the now continuous guide rails  15  and  17  until they reach the final orientation operation at the feeder wheel  36 . 
     As well as spacing and rotating preforms as they pass between the auger screws  23  and  25 , the rotation rate of the auger screws is such as to deliver a preform to the feeder wheel  36  in synchronization with the rotation of that wheel. Furthermore, the rotation of the auger screws provides pressure to ensure preforms proceed down the main support rails. 
     Transfer to Preheating 
     Referring now to  FIG.  5    and  FIG.  6   , a first rotating transfer system  42  is positioned adjacent the feeder wheel  36  with a continuously rotating carrier  44  of the first rotating transfer system  42  and the feeder wheel  36  contra-rotating one to the other. 
     The rotating carrier  44  of the first rotating transfer system  42  includes, in this embodiment, four opposing support arms  46  extending radially from a fixed centre of rotation  48  to rotate about as vertical axis  50 . Each end of the arms carries as first pick and place apparatus  52 . Each fast pick and place apparatus  52  includes a linear guide  54 , a housing  56  which is rotatably mounted to the outer end of the support arm  46 , enabling rotation of the housing  56  about a vertical axis  51 . A two-fingered gripper  58  is mounted to a rotary actuator  60  supported by vertical plate  62  at an outer end of a free sliding element  64  of the linear guide  54 . The gripper fingers  66  are centred on a gripper effective vertical axis  68 , with the gripper able to be rotated about the horizontal axis  61  of the rotary actuator  60 . 
     A fixed horizontal cam plate  70  is mounted at a level below the rotating carrier  44  so that its centre is coincident with the vertical axis  50  of the rotating carrier. The perimeter edge  72  of the cam plate  70  forms an outer cam surface  74  and its upper surface  76  is provided with a cam channel  78  which is inboard of the perimeter edge  72  and the outer cam surface  74 . 
     The housing  56  of the linear guide  54  is provided with an outrigger arm  80  extending radially from the centre of rotation  82  of the linear guide  54 . The outer end of the outrigger arm  80  supports a first cam follower  84  locating in the cam channel  78 . The free sliding element  64 , adapted to reciprocating linear motion in a horizontal plane, is provided with a second cam follower  86  with the free sliding element  64  biased by springs  88  to maintain contact between the second cam follower  86  and the outer cam surface  74 . 
     The cam channel  78  and outer cam surface  74  are arranged so that as a first pick and place apparatus  52  rotates past the preform pick off position  26 , the rotation of the rotating carrier  44 , combined with the loci of the first and second cam followers  84 , 86  causes the gripper  58  to be both reciprocatingly extended and retracted, and rotated relative the arm  46 . The gripper motion is such that at the approach to the preform pick off position  26 , the free sliding element  64  and thus the gripper  58  is extended followed by rotation of the linear guide  54  and gripper  58  in retrograde or negative direction relative to the direction of rotation of the rotating carrier  44 . 
     At the instant a preform  12  arrives at the pick off position  26  after its approximate orientation, so that the handle  20  of the preform is trailing but not yet fixed, the extending movement of the gripper  58  through the first cam follower  84  against the outer cam surface  74 , brings the gripper effective axis  68  into coincidence with the central axis of the preform. At this instance also, a pair of opposing actuators located under the pick off position  26  simultaneously briefly close on, and then release, the preform handle  20  to fix its orientation relative the gripper  58  which, also at that instant engages with the neck  18  of the preform. The gripper  58  is then rotated positively to carry the preform  12  clear of the supporting short rail  40  and away from the pick off position  26 . 
     This combination of reciprocating rotation and extension and retraction of the gripper  58  compensates for the divergence of the loci of the supporting tooth formation  38  of the feeder wheel  36  and the rotating carrier  44  as they contra rotate one relative the other. It is by the means of the reciprocating rotation and retraction movements of the gripper through a combination of a rotating linear guide and the two cam loci that a smooth continuous transfer of preforms is possible between two rotating elements that of the feeder wheel  36  and the rotating carrier  44 . 
     Loading into Mandrel Stage 
     With reference now to  FIG.  7   , rotation of the rotating carrier  44  brings a preform  12  retained in a gripper  58  to the preheating stage  28  as was shown in  FIG.  3    of the machine  10 . Because the preheating of the preforms is conducted with the preforms inverted from their initial position at the pick off position  26 , that is, with the neck  18  upward, the rotary actuator  60  at the end of the free sliding element  64  rotates the grippers  58  and the preforms through 180 degree during their transit between pick off position  26  and the transfer to a preheating transport system  90 . The effect of this rotation is that the handle  20  of the preform is now “leading” with respect to the direction of rotation of the rotating carrier  44 , instead of trailing as it was at the pick off position  26  as could be seen in  FIG.  5   . 
     The preheating transport system  90  is also in continuous movement and comprises a loop rail system  92  with proximate and distal rotating guide wheels  94  and  96  respectively at either end of the loop. A plurality of preform supporting mandrels  98  are adapted to move around the loop rail system  92 , driven into motion around the straight sections of the loop by a drive chain (not shown) to which they are fixed and around the guide wheels  94 , 96  by nesting in niches  103  of the guide wheels. As well as travelling around the loop rail system  92 , the mandrels  98  are continuously rotated about their vertical axes. 
     Preheating of the preform  12  is required for the body  16  of the preform, that is for that portion of the preform which will be subjected to stretching and blow-moulding, to sufficiently soften the polymer. But the handle  20  and the neck  18  which retain their as injection moulded form in the blown container shown in  FIG.  3   , must be protected from excessive heat as the preform moves through the preheating stage. For this reason, as shown in  FIG.  8   , a preform supporting mandrel  98  is provided with a heat shield  100  comprising a channel  102  rising from a cylindrical collar  104  in which the handle  20  is protected while the neck  18  is protected by its insertion into the cylindrical collar  104  of the mandrel. 
     It may be noted that the patterns of the outer cam surface  74  and that of the cam channel  78  of the first rotating transfer system  42  as shown in  FIG.  5   , near the pick off position  26  differ from those at the approach to, and following the preform transfer to preheating position  106 . This reflects the difference in movements required of a gripper  58  as it steers the preform into the position in which the vertical axis of the preform becomes aligned with that of the cylindrical collar  104  of the mandrel  98  and the handle  20  is aligned with the heat shield channel  102 . At the instant these axes are aligned and the handle  20  of the preform is aligned between the side elements of the channel  102 , a cylindrical plunger  108  within the collar  104  rises into the neck  18 , then lowers to bring the neck to an inserted position within the collar. These movements of course take place while the first rotating transfer system  42  and the proximate guide wheel  94  are in continuous contrarotation. This complex movement is again made possible by the combination of the rotation of the arm  46  and the rotation and linear movements of the free sliding element  64 , and thus of the gripper fingers  66  of the first pick and place apparatus  52 . 
     Thus the transfer of a preform from the gripper of the first transfer system  42  to a preform supporting mandrel  98  is achieved in one fluid motion as the vertical axis of the preform is brought into alignment with that of the mandrel and the oriented handle of the preform slides into the heat shield, while accommodating each of the rotations of the loop rail, the mandrel and the transfer system as well as the movements of the gripper. 
     Preheating of Preforms 
     As best seen in  FIGS.  3  and  8   , banks  110  of heating elements  109  are positioned along each of the straight sections of the loop rail system  92 . Graded hot air  111  is drawn across the path of the preforms  12  by extractor fans  113 . To prevent excessive heat build-up of the cylindrical collar  104  and the neck  18  of the preform in the collar, a cooling air stream  115  is directed at the collars. 
     As a mandrel  98  and preform  12  are rotated away from the transfer-to-preheating position  106  by the proximate rotating guide wheel  94 , the mandrels supported in the chain of the preheating transport system  90  travel along the first straight section  112 , around the distal rotating guide wheel  96  and back along the second straight section  114  to arrive at a transfer-from-mandrel position  116 . While traversing these straight sections, the mandrels are rotated about their vertical axes by a gear  105  of the mandrel engaging with chain  107  to evenly expose the bodies of the preforms to heat from the banks  110  of heating elements  109 . The heating elements  109  are each arranged as a series of infra-red heating elements which are individually adjustable as to their proximity to the passing preforms. 
     It will be understood that the orientation of each mandrel  98  at both the transfer to preheating position  106  and at the transfer from mandrel position  116  is critical to allow the respective first and second transfer systems to insert and extract a preform handle from the channel of the mandrel&#39;s heat shield. These heat shield orientations with respect to the periphery of the proximate guide wheel  94  are not the same at these two positions so that the orientation of the mandrel and its heat shield need to be changed from that demanded at the handle extraction position to that required at the handle insertion position. 
     To this end, each mandrel is provided with a guide carriage  98   a  fixed to the mandrel. As a mandrel approaches the transfer-from-mandrel position  116 , cam followers  98   b  and  98   c  engage with guide channels to rotate the mandrel into the required orientation. During transit about the periphery of proximate guide wheel  94 , the cam followers  98   b  and  98   c  follow cam channels of a cam plate above the proximate guide wheel to bring the orientation of the heat shield to that required at the transfer-to-preheating position  106 . 
     Transfer to Mould 
     With reference now to  FIG.  9   , a second rotating transfer system  118  operates to transfer preforms  12  from the preheating transport system  90  to a stretch blow moulding die assembly  120 . The stretch blow moulding die assembly  120  comprises of roar stretch blow moulding dies  30 , two of which can be seen in the truncated view of the machine in  FIG.  9   . In the present embodiment, four radially disposed stretch blow moulding dies  30  rotate continuously about a common centre  122 . 
     The second rotating transfer system  118  is of similar configuration to that of the first rotating transfer system  42  described above. That is, it includes a cam plate  124 , also provided with an inboard cam channel  126  and an outer cam surface  128  around its periphery. 
     In this instance, second rotating transfer system  118  includes two, rather than four, continuously rotating opposing radial arms  130 , each of which carries a second pick and place apparatus  132 . Again, similar to the first pick and place apparatuses  52  of the first rotating transfer system  42  above, each includes a linear guide rotatably mounted to the respective outer end of the radial arm  130 , with the free sliding element of the linear guide supporting a rotary actuator which, in turn supports a gripper. In this arrangement also, a first cam follower of an outrigger arm attached to the housing of the linear guide, locates in the inboard cam channel  126 , while a second cam follower of the free sliding element of the linear guide remains in contact with the outer cam surface  128  by means of a spring. 
     Preforms still retained in preform supporting mandrels  98  arrive back at the rotating proximate guide wheel  94  of the preheating system and approach the transfer-from-mandrel position  116 , and are rotated into the required orientation of the heat shield as explained above. The cylindrical plunger  108  of a mandrel  98  approaching the transfer-from-mandrel position  116 , lifts the preform so that the neck is clear of the cylindrical collar  104  to allow the gripper of the second rotating transfer system  118  to engage the preform by the exposed neck  18 . Again, it is the motion of the gripper induced by the combination of rotation of the radial arm  130 , the rotation of the linear guide and linear movements of the free sliding element supporting the gripper as controlled by the cam channel  126  and outer cam surface  128 , which allows the preform and its handle to be smoothly removed from the preheating transport system  90 . 
     As one rotating radial arm  130  of the second rotating transfer system  118  approaches and removes a preform from the preheating transport system  90 , the opposite radial arm approaches the die loading position  134 . During its rotation from the transfer-from-mandrel position  116  to the die loading position  134 , the rotary actuator of the second pick and place apparatus  132  rotates about its horizontal axis to change the preform from its inverted position held during the preheating stage, back into an upright position. (It should be noted that  FIG.  9    shows both a rotating arm  130  and a stretch blow moulding die  30  approaching the die loading position  134 ) 
     Stretch blow moulding dies of the die assembly  120 , are in the form of two die halves  136 , one of which is shown in  FIG.  10   . Die halves  136  are hinged together about a vertical axis  142  in the manner of a bivalve, and with the hinge supported from a central structure  146  of the die assembly  130  in a typical arrangement for radial stretch-blow-moulding machines. The face surface  138  of the die half shown in  FIG.  10    has been shaded to highlight the die cavity  148  for the body  16  and integral handle  20  of the preform. As is common in the stretch-blow-moulding of containers, the neck  18 , which remains unaltered in the stretch-blow-moulding process, projects out of the die when closed. 
     Referring again now to  FIG.  9   , as stretch-blow-moulding dies  30  approach the loading position  134  the die halves open symmetrically about a bisecting radial line  152  passing through the centre of rotation  122  and the vertical axis  142  of the die hinge  144 , in preparation for receiving a preform. It may noted from  FIGS.  3  and  9   , that the rotation centres of the second rotating transfer system  118 , the proximate rotating guide wheel  94  of the preheating stage and that of the stretch-blow-moulding die assembly  120 , lie along a straight line  154 . 
     As an opened die  30  approaches the die loading position  134  lying on the straight line  154 , a radial arm  130  with a preform retained in the gripper of the second pick and place apparatus  132  also approaches the loading position. As the bisecting radial line  152  of the die halves  136  becomes coincident with the straight line  154 , the movements of the second pick and place apparatus  132  has brought the gripper effective vertical axis and thus the vertical axis of the preform into coincidence with the axis  156  of the die (as defined by the centre of the preform body when held in the die) and with the handle oriented to lie in the vertical plane defined by the straight line  154 . While the die halves close and the paths of the die  30  and the end of the rotating arm  130  begin to diverge, the rotation and extension of the gripper, still holding the neck  18  of the preform, ensures the orientation of the handle is maintained in that vertical plane defined by the bisecting line of the die halves until closure is complete. The gripper then disengages from the preform neck. 
     It can be seen from  FIG.  10   , that the curved section of the handle  20  of the preform is nested in a constricting cavity  150  of the die which ensures that the handle is not distorted, nor the region between the junction points  22 , 24  stretched. The underside of the straight section of the handle forms a surface which, in effect, determines the shape of the container under the handle. 
     With the die halves  136  closed, stretch-blow-moulding of the container proceeds and the die  30  loaded at the die loading position  134  rotates towards the die unloading position  158  as shown in  FIG.  11   . 
     Container Unloading 
     A third rotating transfer system  160  is located adjacent the stretch-blow-moulding die assembly  120 , and is configured in similar manner to that of the first and second rotating transfer systems  42 , 132  described above. As for the second rotating transfer system  132 , the third rotating transfer system  160  includes opposing radial arms  162  at the ends of each of which is a third pick and place assembly  164 . It does not however include a rotary actuator since the container which emerges from the die remains in an upright position through the discharge process. 
     As for the first and second rotating transfer systems, movements of a gripper  166  is controlled by a combination of the rotation of the opposing radial arms  160 , the linear movement of the free element of the linear guide and the two cam loci. 
     As the stretch-blow-moulding die  30 , now containing a finished container  14 , nears the die unloading position  158  lying on the line  168  joining the centres of rotation of the stretch-blow-moulding die assembly  120  and of the opposing radial arms  160  of the third transfer system, the gripper of the pick and place is maneuvered into position to grasp the neck of the container. As the die reaches the die unloading position, the die halves open and the gripper extracts the blown container  14  from the die  30 . 
     The third rotating transfer system  160  continuous to rotate, tanking the container  14  held by the gripper  166  into a discharge channel  172 , with the base of the container passing over a guide rail  170 . Guide rail  170  transitions from concentricity with the third rotating transfer system to concentricity with a rotating two-tiered outfeed wheel  172 . As the container  14 , now in the discharge channel  172 , reaches a release position  174  lying on the line  176  joining the centres of rotation of the third rotating transfer system  160  and that of the outfeed wheel  172 , the gripper  166  releases the neck and retracts. At the same time a scalloped indentation  172   a  of the rotating outfeed wheel captures the body of the container feeding it into a discharge channel  178 . As containers follow the path of the gripper  166  and then a path determined by the outfeed wheel  172 , the base of the container receives cooling air from orifices  182  in guide rail  170 , backpressure from accumulating containers in the discharge channel  172  force containers to drop into a container receiving bin  180 . 
     Control of the Machine 
     The operation of the machine  10  is under the control a programmable logic controller. As well as ensuring that all rotation drive servo motors operate synchronously, the controller provides for fully adjustability of the parameters of the preheating elements and of the parameters of the stretch-blow-moulding dies. This includes setting differential temperature gradients allowing for a gradually increasing exposure to heat as preforms progress around the preheating transport system, and automatic adjustment of heating element temperatures for changing ambient temperatures. 
     Control of the preheating is particularly critical in the present system because of the unique characteristics of the preform dictated by the integral handle of the preform. The preheating is thus designed to allow for lateral flow of material in the area between the two junction points of the handle while limiting longitudinal flow and extension during the stretching phase of the stretch-blow-moulding process. Instead, the manner in which heat is applied to the preform ensures that the bulk of polymer which forms the outer shell of the container of  FIG.  2   , is produced from that region of the preform below the lower junction point of the handle. 
       FIG.  12    is a schematic block diagram of control components associated with control of the heating and transport of the preforms usable with any of the above described embodiments. 
     As best seen in the inset of  FIG.  12   , banks  110  of heating elements  109  are positioned along each of the straight sections of the loop rail system  92 . Graded hot air  111  is drawn across the path of the preforms  12  by extractor fans  113 . To prevent excessive heat build up of the cylindrical collar  104  and the neck  18  of the preform in the collar, a cooling air stream  115  is directed at the collars. 
     In a preferred form each bank  110  comprises a module  201 . The modules  201  are arranged sequentially around the conveyer  202  as illustrated in  FIG.  12   . 
     In a preferred form a processor  203  in conjunction with memory  204  executes a program for control of the heating elements  109  of the modules  201 . 
     In a particular preferred form each element  109  of each module  201  is controlled individually by the processor  203 . 
     In an alternative preferred form the elements  109  are controlled as a group based on height—so the top most elements  109  of the modules  201  are controlled to a predetermined temperature together whilst the next down in height elements  109 B are also controlled together to a predetermined temperature—and so on down to elements  109 G at the lowest level. 
     In addition the processor  203  controls the speed of rotation of motor  205  in order to control the continuous speed of the preforms  16 . 
     A temperature sensor  206 , in one form an infrared temperature sensor provides environment temperature sensing which is utilised by processor  203  to modulate the degree of heating of all elements  109  by a difference factor delta (Δ). 
     This allows for a global control of the system temperature in response to variations in ambient temperature. 
     As noted above, the stretch-blow-moulding machine is especially developed for, and adapted to, the feeding and transportation of a non-symmetrical preform with integral handle and, ultimately the stretch-blow-moulding of that preform into a container with an integral handle. The preform according to the invention may take a number of different forms described below, although common to all are the neck portion  18  and the integral handle  20  as shown in  FIG.  1   . 
     The preforms now to be described differ primarily in respect of the configuration of their internal surfaces, offering benefits of improved distribution of polymer material to the walls of the blown container as well as significant improvement in economy of manufacture due to reductions in the volume of polymer required. 
     First Preferred Preform Embodiment 
     In a first preferred a preform  310  according to the invention as shown in  FIG.  13 A  includes a finished neck portion  312  and a tubular hollow body portion  314  extending from below the neck portion. Similar to preforms of the prior art, the outer surfaces of the body portion  314  are defined by diameters centred on a central vertical axis  316 , so that the body portion  314  approximates a cylinder but with a decrease in diameters from the neck portion  312  to the closed end  318  of the preform. 
     The internal surfaces of the preform  310  include surfaces of the hollow body portion  314  which are not concentric with the outer surfaces. Preferably, as shown in  FIGS.  15  and  16   , cross sections of the internal surfaces of the preform  310  are circular and concentric in the neck portion  312  of the preform as indicated by the cross section A-A, but below the neck portion are of ovoid form as indicated by section B-B. All sections are however centred on the central longitudinal axis  316  of the body of the preform. 
     Referring now to  FIG.  14   , in a preferred arrangement, the mandrel  322  around which the preform  310  is injection moulded, comprises an upper region  324  of circular cross sections adapted to position and retain the mandrel in its correct position in an injection moulding cavity. A first preform-defining portion  326  of the mandrel extends from this upper region  324  to a depth equal to that of the neck portion  312  and is of circular cross section A-A as shown in  FIG.  4    to form the concentric walls of the neck portion. The ovoid portion  328  of the mandrel depends from the first portion  326 , extending to the tip  330  of the mandrel. 
     Given the ovoid shape of the cross sections of the ovoid portion  328 , there is a short transition portion of the mandrel immediately below portion  326  forming the internal form of the neck portion, which transitions from the circular cross section A-A of portion  326  to the ovoid sections B-B. This transition thus takes the form an asymmetrical frustum of a cone; an upper end of which has a diameter equal to that of a lower end of the first portion  326  with the lower end of the transition portion conforming in cross section to the upper end of the ovoid cross section B-B of the remaining length of the preform. 
     It can be seen from  FIG.  13 A , that both the outer surfaces of the body portion  314  of the preform and the ovoid portion of the inside surfaces as defined by the mandrel  322 , are tapering; that is, the diameters defining the external surface of the preform are decreasing from below the neck portion  312  to the bottom  318 , while similarly, the major axis  344  and the minor axis  342  of the cross sections of the ovoid portion  328  also decrease accordingly. 
     Referring still to  FIG.  13 A , the preform  310  of the invention further includes, as noted above, an integral handle  334  which forms a loop of material extending vertically from an upper junction  336  below the neck portion  312  to a lower junction  338  with the outer surface of the preform. The handle  334  is centred on and defines a central vertical plane  340  (lying in the plane of the paper) which contains the central longitudinal axis  316  of the preform. 
     The mandrel  322 , and thus the internal surfaces of the ovoid portion  328 , are so oriented relative the handle  334 , that major axis  344  of the ovoid cross section B-B lies in the central vertical plane  340 . 
     It can thus be seen from  FIG.  16    and cross section B-B that the wall thicknesses of the preform  310  in that portion  328  of the preform in which the inner surfaces are defined by the ovoid cross section, varies from a maximum at opposite ends of the minor axes  342  of the ovoid cross section to minimum thicknesses at outer ends of the major axis  340 . Preferably, the ratio of maximum wall thickness to minimum wall thickness of the ovoid portion lies in the range of 2:1 and 2.2:1. 
     The distribution of polymer in the preform according to the invention, afforded by the non-symmetry of the ovoid portion, allows polymer walls of the preform in the region of maximum thickness to be biased predominantly towards the longer side walls  346  of a rectangular cross section blown container  348 , while the polymer walls of the preform from the region of minimum thickness is predominantly distributed towards the shorter side walls  350  of the blown container such as shown in  FIGS.  17  and  18   . It can be seen from FIGS.  17  and  18  that the longer side walls  346  lie on either side of the central vertical plane  340  and thus the handle  334  so that the alignment of the major axis  344  with the vertical plane  340  ensures that the polymer from regions of maximum wall thickness are directed to those longer side walls. In preferred forms the preform of the first embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Second Preferred Preform Embodiment 
     With reference now to  FIG.  19   , in this preferred embodiment, the exterior surface  410  of the preform  400  of this embodiment, is of substantially cylindrical form. As for the first embodiment above, it too includes an integrally injection moulded handle  434 . In this embodiment, the internal surfaces  414  of the preform are consistently circular in section as shown in the two sample cross sections  FIG.  17 A  and  FIG.  17 B . However, again as is clear from the two cross sections and the sectioned side view of  FIG.  17   , there is a tapering of the internal surface  414  so that the wall sections, though concentric to the external surface, increase from a minimum thickness at the neck portion  412  of the preform to a maximum proximate its lower end  418 . In preferred forms the preform of the second embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Third Preferred Preform Embodiment 
     In this further preferred embodiment of the invention, a preform  500  as shown in  FIG.  20   , is formed to significantly reduce the volume of material required to produce the containers shown in  FIGS.  17  and  18   . As in the embodiments above, the preform  500  includes an injection moulded integral handle  534 . Although in this embodiment, the neck portion  512  is identical in its exterior and internal forms to that of the earlier embodiments, there is a substantial reduction in the diameter of the substantially cylindrical portion of the body of the preform below the neck portion. 
     In this embodiment also, as in the second preferred embodiment above, the internal surfaces of the preform are consistently circular in section as shown in the two sample cross sections A and B of  FIGS.  20 A and  20 B , but taper with the wall sections increasing from the minimum thickness obtaining in the neck portion and through the transition in diameters below the neck portion, to a maximum wall thickness proximate the lower end  518  of the preform. 
     As a further means of reducing the volume of material in the preform of this embodiment, the outer surface  510  below the neck portion  512 , also tapers towards the lower end  518 . In preferred forms the preform of the third embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Fourth Preferred Preform Embodiment 
     With reference now to  FIG.  21   , this preferred embodiment of a preform  600  according to the invention, shares a number of characteristics with that of the first and second preferred embodiments above. It has, (as have all the preform embodiments of the present invention), an integral handle  634  as previously described, and, as in the first preferred embodiment above, the internal surfaces  614  of the preform are not consistently of circular section throughout the length of the preform. However, the external surfaces  610  of the perform are substantially cylindrical in form as in the second preferred embodiment. 
     Thus, although the external surfaces  610  are defined by circular cross sections, the internal surface  614  varies from circular in cross section from the neck portion  612  down to section A-A in  FIG.  21 A , to then transition to an ovoid section B-B as shown in  FIG.  21 B , approaching the lower end  618 . 
     A feature of this particular embodiment is that the wall thickness of the ovoid portion of the internal surface  614  of the perform at the ends of the major axes remains constant with the wall thicknesses of the concentric cross sections from section A-A and upwards, while there is a thickening of the walls increasing to maximum at the minor axis of the ovoid cross section. In preferred forms the preform of the fourth embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Fifth Preferred Preform Embodiment 
     The preform of this embodiment of a preform  700  shown in  FIG.  22    is similar to that of the fourth preferred embodiment above, but here, as shown in the cross section views A-A and B-B of  FIGS.  22 A and  22     b,  the wall thickness at the outer ends of the major axes of the ovoid cross section portion of the preform is not maintained equal with the wall thickness of at and below the neck portion  712 . Rather the wall thickness gradually increases from below the neck portion towards the lower end  718  of the preform. 
     It may be noted at this point, that in those forms of the perform as in this embodiment and that of the first preferred embodiment above, shaping the internal surface in these non-concentric forms of outer and inner surfaces, introduces considerable issues for the injection-moulding of the preforms. 
     As shown in  FIG.  24   , preforms, including those of the present invention, are typically injection moulded in multi-cavity dies  800  in which the cavities  820  in the die conform to the outer shape of the preform, including in the present cases, the shape of the integral handle. In preforms with concentric wall thicknesses, that is, with circular cross sections, the mandrels  840  for forming the internal surfaces will also be of circular cross sections. Thus, the only requirement for positioning such a mandrel relative the injection-moulding cavity is its concentricity with the neck portion of the cavity. 
     A mandrel for producing an internal surface of a perform which is wholly or partially non-circular in section may firstly require, a considerably more complex machining operation and, secondly it must be specifically oriented in the injection-moulding cavity. 
     Mandrels for preforms with non-circular cross sections must be positioned within the cavities of an injection-moulding die  820 , one half of which is shown in  FIG.  24    so that the major axes of the ovoid portion are aligned relative to a vertical central plane of the cavities. For preforms according to the present invention with integral handles, that vertical plane is the plane on which the handle of the preform is centred as set out above (in effect the face  842  of the die half). 
     To be effective in biasing polymer material flow from different wall thickness areas of the preform towards designated regions of blown container, the orientation of the preform must be maintained in the cavity of the stretch-blow-moulding machine. That is, the vertical plane of the preform must coincide with a defined vertical plane of the container. In the present invention the vertical plane of the preform is defined by the integral handle and is made coincident in the stretch-blow-moulding cavity with the central vertical plane of the blown container which again is central to the integral handle of the container. 
     In a moulding cycle, the die halves are brought together to close the die and the array of mandrels  840  driven into the cavities  820 . The injection nozzle  848  is then advanced into the injection pocket  844  and molten polymer forced through the runner system  846  to fill the spaces between the external surfaces of the cavities  820  and the mandrels  840  to produce the preforms. 
     Although the above description has focused in some embodiments on use of ovoid or offset cross sections to vary the wall thicknesses of at least a portion of a preform at any given cross section of that portion, it will be understood that such variation can be achieved with other non-concentric shaping of the mandrel. Again, although the ovoid cross sections described for the preferred embodiment are centred on the vertical axis of the preform, other material distribution effects may be achieved by an asymmetric positioning of these cross section. In preferred forms the preform of the fifth embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Sixth Preferred Preform Embodiment 
     This further preferred embodiment of a preform according to the invention and shown in  FIG.  23   , the preform  900  is provided with a wall thickness  911  in the region between the junction points  936  and  938  of the integrally injection-moulded handle  934  specifically to optimise control of the material in this region in the stretch-blow-moulding stage of producing a container from the preform. 
     In this embodiment, the external surface  910  of the preform is again substantially cylindrical. The internal surface of the preform is likewise formed of circular cross sections, but as can be seen in both the side sectioned view of  FIG.  13 A  and cross section AA of  FIG.  13 A , the centres of a portion of the cross sections (typified by section A-A) do not lie on the central axis  930  of the body of the preform, but are offset towards the handle  934 . 
     The effect is to “thin” the wall thickness in the region between the junction points  936  and  938  of the handle. This is possible and desirable, because firstly there is a lesser volume of material required to form the container since there is no longitudinal stretching of this region and, secondly the thinning provides a significant cost saving in material. 
     It will be understood that all the above embodiments of the preform seek to optimise both the distribution of the polymer material of the preform into the blown container and do so by reducing the weight and thus the volume of material for reasons of economy of production. In preferred forms the preform of the sixth embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Seventh Preferred Preform Embodiment 
     With reference to  FIGS.  26  and  27   , a preform  1000  for stretch-blow-moulding the container  1040  shown in  FIG.  28   , is comprised of a neck portion  1012 , a collar  1014  and a body  1016  extending from below the collar. As in the preform according to prior art shown in  FIG.  1   , the preform  1000  includes an integral handle  1018  joined to the body  1016  at first junction position  1020  just below the collar  1014  and a second junction position  1022  along the length of the body. 
     The first cylindrical portion  1024  of the body extending below the collar  1014 , is substantially of constant diameter, and in the region immediately below the collar, the diameter is substantially that of the finished container as can be seen in  FIG.  28   . 
     But it can be seen firstly from a comparison between the preform  1000  according to the present invention, and the preform of the prior art, that there is a significant reduction in diameter of the body  1016  below the first cylindrical portion  1024 . 
     Furthermore, it is clear that this second portion  1026  of the body, between the reduction in diameter and the tangent line  1028  with the bottom portion  1030 , is not cylindrical but forms a portion of a narrow cone, with the base diameter  1030  of the cone, that is its largest diameter, significantly smaller than the diameter of the first cylindrical portion  1024 . Thus, this large reduction in diameter and the tapering provide a first significant reduction in the volume of PET contained in the preform of the invention. 
     Turning now to the cross-section view of  FIG.  27   , the walls of the body  1016  of the preform  1000 , vary considerably in thickness. While the wall thickness of the neck portion  1012  and the first portion  1024  below the collar  1014  are substantially of a constant thickness, that of the second portion  1026  varies from a relatively thin wall section at the base diameter  1030 , to a maximum thickness proximate the tangent line  1028 . 
     The wall thickness of the bottom portion  1032  is further varied being reduced from the maximum thickness at the tangent line  1028  to a minimum at the base of the bottom portion. 
     This thinning of the wall thickness in the region below the maximum diameter  1030  of the second portion  1026 , augments the reduction in material volume provided by the diameter reduction and the form of the second portion  1026 . 
     As well as providing savings in material volume, these variation in wall thicknesses are designed to evenly distribute the volume of PET material to various areas of the walls of the stretch-blow-moulded container  1040  shown in  FIG.  28   , to an average thickness of approximately 0.5 mm. In preferred forms the preform of the seventh embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Eighth Preferred Preform Embodiment 
     With reference to  FIGS.  33 ,  34  and  35    there is illustrated a preform having an integral handle with a flared portion thereby to impart an ergonomic aspect to the lifting of containers blown from the preform. 
     Turning now to  FIG.  33   , in a preferred form of the preform, a preform  2100  includes a neck  2102 , a body portion  2103  and a handle  2113 . The neck  2102  has a threaded portion  2104  and a locating ring  2105 . The preform is injection moulded from PET material in accordance with the teaching elsewhere in this specification. The handle in its configuration as injection moulded in its preform state, remains unaltered by the stretch blow-moulding process forming the resulting container from the continuous blow moulding process described elsewhere in this specification. 
     In order to produce the container, the preform  2100  shown in  FIGS.  33  to  35   , is fed into a blow moulding machine such for example as the machine  10  shown schematically in  FIG.  3   , and blow moulded according to bi-axial orientation blow moulding techniques. During this process the neck  2102  is held in a mandrel  322 , as shown in  FIG.  14    of a transport system of the machine  10  in such a way as to prevent its expansion in the stretch blow-moulding die  30 . 
     The loop of orientable material forming the handle  2113  has a generally uniform cross section from proximate the lower connection region  2116  to a gradually widening cross section  2124  approaching the upper connection region  2115  with the cross section reaching and maintaining a maximum width proximate the upper connection region  2115  as can be seen in  FIGS.  34  and  35   . 
     With reference again to  FIG.  33   , integrally moulded first, second and third strengthening elements  2135 ,  2136  and  2137  are provided respectively at each of the upper connection region  2115 , the lower connection region  2116  and at the junction between the straight section  2118  and the arcuate section  2120  of the handle  2113 . 
     The first strengthening element  2135  at the upper connection region  2115  comprises a curved strengthening element conforming generally in width and in cross section to the width and cross section of the widened portion  2124  of the handle proximate the upper connection region. The curved strengthening element extends from a first separate connection region  2140  on the body portion  2103  of the preform (and on the blown container) below the upper connection region  2115  and merges with the loop of orientable material proximate a first end  2141  of the maximum width of the handle. 
     The second strengthening element  2136  at the lower connection region  2116  of the handle, comprises a straight strengthening element conforming generally in width and cross section with the width and cross section of the straight section  2118 . The straight strengthening element extends from a second separate connection region  2142  above the lower connection region  2116  of the straight section of the handle, to merge with the straight section of the handle proximate the lower connection region. 
     The third strengthening element  2137  at the junction of the straight section  2118  and the arcuate section  2120  of the handle, comprises a further curved strengthening element conforming generally in width and cross section with the width and cross section of the handle of both the straight section  2118  and the arcuate section  2120  adjacent the junction. Respective outer ends of this further curved element merge with each of the straight  2118  and arcuate  2120  sections. 
     It should be noted that, in this instance, the width of the first strengthening element  2135  is the same as that of the maximum width of the widened part  2124  of the handle proximate the upper connection region  2115 . It is this increased width of the first strengthening element  2135  which provides for a larger area for distributing the load of a container over the index finger of a hand (not shown) lifting the container, while the curvature of the first strengthening element is selected to fit comfortably on the average index finger of a human hand. 
     Preferably, each strengthening element  2135 ,  2136  and  2137  includes a web of orientable material within boundaries formed respectively between the body portion  2112  of the preform and the first and second strengthening elements  2135  and  2136 , and between the third strengthening element  2137  and the straight and arcuate sections  2118  and  2120 . Each web of orientable material is aligned with and extends equally in both directions from the central line  2132  of handle. In preferred forms the preform of the eighth embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Ninth Preferred Preform Embodiment 
     With reference to  FIG.  36    there is illustrated a ninth embodiment of the preform showing alternative cross section arrangements for the purpose of reducing volume of the preform. In this instance like components are numbered as for the fourth embodiment with reference to  FIG.  21   . In this instance the cross section wall profile as shown in section AA and section BB is rotated 90 degrees as compared with the wall profile of  FIG.  21   . In preferred forms the preform of the ninth embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Tenth Preferred Preform Embodiment 
     With reference to  FIG.  37    there is illustrated a tenth embodiment of the preform showing alternative cross section arrangements for the purpose of reducing volume of the preform. In this instance like components are numbered as for the fifth embodiment with reference to  FIG.  22   . In this instance the cross section wall profile as shown in section AA and section BB is rotated 90 degrees as compared with the wall profile of  FIG.  22   . In preferred forms the preform of the tenth embodiment is produced by an injection moulding process as described earlier in this specification. In preferred forms the preform thus produced is reheated and blown on a continuously rotating, non-symmetric preform feed, stretch-blow-moulding machine as described earlier in this specification. 
     Notes on the Handle 
     In preferred forms the integral handle of the preform is not substantially deformed or substantially changed in shape during the stretch-blow-moulding process but substantially retains its as-injection-moulded shape. The blow-moulding cavity shown in  FIG.  10    includes a recess specifically shaped to the form of the handle as injection moulded. This it will be understood is also a primary function of the heat shield to protect the handle from heat which could cause distortion of the handle while the preform is transported around the preheating stage of the machine. 
     Injection Moulding of Preforms 
     A preferred system of injection moulding any one of the above described preforms will now be described with reference to  FIGS.  29  to  31   . As noted elsewhere, the integral, double connect handles of the containers which are stretch-blow-moulded from the preforms, introduce considerable complexity in the design and operation of the injection moulding tooling. 
     Typically, in the injection moulding of preforms for symmetrical or non-handled containers, the bodies of the preforms below the neck are formed in cavities in the “hot”, fixed section of the injection moulding die, with the threaded neck portions formed in opposing half cavities carried on the face of the moving die section. After a mould cycle, when the die opens, the bodies of the preforms are drawn out of their cavities by the necks which, at this first opening stage, are retained in the still closed opposing half cavities and move with the opening die section. The opposing half cavities now part to release the necks and a stripper plate is activated to force the preforms off the cores (which are fixed to the moving die section). 
     With reference now to  FIG.  29  to  31   , for preforms  1100  with handles  1112 , only that section  1114  below the handle can be formed in cavities  1116  in the heated, fixed section  1118  of the die  1120 , with the neck  1122  and handle  1112  formed in much longer and more complex opposing half cavities  1124  carried on the moving die section  1126 . Again, the cores  1128  to form the internal shape of the preforms  1100  are fixed to the moving die section  1126  and are located on the common axis of the cavities  1116  in the heated fixed side of the die and the opposing half cavities. 
     In contrast to the demoulding of symmetrical preforms, the bodies of which are exposed to air immediately the die opens, a much larger section of the preforms of the present invention is retained in the opposing half cavities  1124  and therefore require a longer delay before preforms have cooled and are sufficiently stable for stripping off the cores  1128 . This adds considerably to the mould cycle time for preforms with handles. 
     In order to reduce cycle time and thus increase production, in the system of the present invention referring now to  FIG.  32   , a robot  1130  (on a portion of the arm of which is shown in  FIG.  32   ) is employed in the demoulding of the preforms  1100 . The robot arm end effector  1132  is fitted with an array  1134  of vacuum cups  1136 , equal in number and spaced according to the number and spacing of the cavities in the injection moulding die as shown in  FIG.  31   . Towards the end of a mould cycle this array  1134  of vacuum cups is poised above (or to the side of) the injection moulding die  1120  and as soon as the die opens sufficiently to allow insertion of the array, the robot brings the array into registered position between the parted sections  1118  and  1126  of the die, and advances the vacuum cups  1136  to fit over the lower ends of the preforms. 
     It is important for correct extraction of the preforms that the handles remain aligned in their as-moulded orientation to prevent rotation of the handles into positions at which they may be caught on edges of the opposing cavity halves. For this reason the vacuum cups are provided with a slot or channel  138  at their outer ends which slides around the lower end of the handle. By this means also a larger portion of the preform is covered by the vacuum cup. Vacuum is now applied to the cups  1136  and the robot retracts the array  1134 , and the preforms  1100  now secured by vacuum pressure in the cups, to draw the preforms off the cores. Once free of the cores the array of vacuum cups and retained preforms are withdrawn from between the heated fixed section  1118  and the moving side  1126  of the die, and rotated so that the axes of the preforms are in a substantially vertical orientation. Vacuum pressure is then cut allowing the preforms to tall from the vacuum cups into a receiving bin. 
     The advantage of the use of vacuum in the demoulding process rather than a conventional stripper plate, is that the application of vacuum aids significantly to the cooling of the preforms, thus allowing their extraction at an earlier point in the mould cycle and shortening that cycle. This is particularly beneficial for the preforms of the present invention in which the end below the handle, being the last part of the preform to be formed (injection proceeding from the tip of the closed end of the preform), is at the highest temperature when the die opens. Additionally the slot or channel which accommodates the lower part of the handle, provides for a greater portion of the preform to be subjected to the cooling provided by air flow into the suction cups when vacuum is applied just before suction cups fully envelop the lower and mid portions of the preforms. 
     The cooling proceeds further as the robot draws the array of vacuum cups and preforms away from the die and over a receiving bin. The array is then rotated from the initial as-removed from the die position, that is with the axes of the preforms horizontal, to the vertical allowing the preforms to fall out of the cups when vacuum pressure is cut, and into the receiving bin. 
     INDUSTRIAL APPLICABILITY 
     The continuous movement of previously injection moulded non-symmetrical preforms from their initial feeding into the machine  10  through the various continuously rotating stages described above, provides a marked improvement in output and quality of containers stretch-blow-moulded from such preforms. This continuous flow from preform infeed to the emceed of container is made possible by the unique features of the transfer systems of the machine and the control of orientation of the preform handles at each transfer, and that of the preform supporting mandrels at transfers into and away from the preheating stage. 
     The preforms of the above described embodiments, provide for the stretch-blow-moulding of a container in the stretch-blow-moulding machine, which is equal in capacity to that of the container of the prior art shown in  FIG.  25   , but with a significant reduction in the volume of PET and conferring an optimum distribution of material from the preform to form the containers shown in  FIGS.  17  and  18   . Thus, the preforms of the invention provides for a considerable reduction in raw material costs in the production of PET containers with integral handle.