Patent Description:
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 <CIT>. The entire disclosure of <CIT> is incorporated hereby cross reference. In that disclosure, preforms enter a production machine such as schematically shown in Figures <NUM> and <NUM> 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 <CIT> 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 <CIT>. 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.

<CIT> 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.

<CIT> 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 <CIT>; <CIT>; <CIT> and <CIT> 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 <CIT> 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.

Other relevant references include <CIT>) which discloses a method that corresponds to the preamble of claim <NUM>; <CIT>); <CIT>) and <CIT>).

It is an object of the present invention to address or at least ameliorate some of the above disadvantages.

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.

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.

Irregular preform: in this specification refers to a preform in which elements of the exterior surface, wall thickness or cross sections vary asymmetrically along an axis or axes or about a median plane of the preform.

Accordingly, in a first 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 an integrally injection-moulded handle portion extending radially; said method comprising:.

characterized in that the preform comprises an open neck portion and a hollow body extending from the neck portion; at least a portion of the walls of the hollow body varying in thickness, and wherein cross sections of at least a portion of inner surface of the hollow body are ovoid in section.

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.

Preferaby, each heating element of each module is controlled individually by a processor.

Preferably, 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).

Preferably, the step of controllably transferring the integral handle PET pre-form onto the continuously moving conveyor includes orienting the handle of the preform into a known orientation at arrival at a pick off position.

Preferably, at least a portion of an inner surface of the hollow body is non-concentric with outer surfaces of the hollow body.

Preferably, the outer surfaces of the hollow body are defined by diameters centred on a central longitudinal axis of the preform to form a substantially cylindrical body. Preferably, centres of the cross sections of ovoid shape are centred on a longitudinal axis of the preform.

Preferably, centres of the cross sections of ovoid shape are offset from a longitudinal axis of the preform.

Preferably, centres of circular cross sections of a portion of the hollow body are offset from a longitudinal axis of the hollow body.

Embodiments of the present invention will now be described with reference to the accompanying drawings wherein:.

A feature of the present machine <NUM>, a preferred configuration of which is shown in <FIG>, is that motion through the machine of a non-symmetric injection moulded preform <NUM> as shown in <FIG>, from its initial intake to its emergence as a stretch blow-moulded container <NUM> (as shown in <FIG>), is continuous. As shown in <FIG>, the previously injection moulded polymer preform comprises a cylindrical elongate body <NUM> and neck <NUM>. An integral handle <NUM> extends from a first junction point <NUM> just below the neck <NUM> to a second junction point <NUM> on the body <NUM> of the preform.

Referring again to <FIG>, the continuous, non-incrementing process of the machine <NUM> includes the transfer of preforms from a loading or pick off position <NUM> to a preheating stage <NUM>, through the preheating stage and transfer to a stretch-blow moulding die <NUM> with subsequent removal of the blown container <NUM> from the die and removal from the machine. These stages will now be described in detail.

As shown in the preferred layout of the machine <NUM> in <FIG> and referring also to <FIG> and <FIG>, the previously injection moulded preforms <NUM> (as shown in <FIG>) are fed, for example from a hopper (not shown but as well understood in the industry) to slide under gravity down inclined rails <NUM> while supported by their necks <NUM>. The inclined rails <NUM> comprise a pair of upper rails 32a between which the preforms are suspended by their necks <NUM>, and a pair of lower rails 32b which constrain the handles <NUM> 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 <NUM> of the preform is controlled precisely.

Preforms <NUM> with a handle roughly oriented pass one by one through an escapement <NUM> to be captured by a continuously rotating feeder wheel <NUM> which carries the preform between the feeder wheel and a short rail <NUM>, in such a way that friction between the body <NUM> of the preform and the rail <NUM> induces rotation of the preform and its handle. The rotating handle collides with a stop 40a under the rail <NUM> forcing each handle into a rearward orientation with respect to the direction of travel, to arrive at a pick off position <NUM>.

At the instance that a preform arrives at the pick of position <NUM>, a pair of opposing actuators (not shown) located under the pick off position <NUM>, simultaneously briefly close on, and then release, the preform handle <NUM> to fix its orientation relative the gripper <NUM> which, also at that instant engages with the neck <NUM> of the preform.

In this second preferred embodiment, with reference now to <FIG>, the injection moulded preforms <NUM> are again fed onto inclined rails 32a, down which they slide under gravity supported by the flanges at the necks <NUM>. Again, as described for the first preferred embodiment above, the handles are loosely constrained between lower rails 32b, 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 34A is located at a point along the rails <NUM> approaching the lower end of the rails. As can be seen in <FIG>, the mechanism includes two contra-rotating drive wheels <NUM> and <NUM>, arranged at opposite sides of the rails <NUM>, at a level coincident with the lowermost portion of the bodies of the preforms and below the lower rails 32b 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 32b are shown in <FIG>.

The drive wheels <NUM> and <NUM> are separated by a gap <NUM> which is somewhat narrower than the diameter of the body <NUM> of the preforms. Each of the wheels <NUM> and <NUM> is provided with one or two tyres <NUM> of a sufficiently soft polymer material to allow a preform body <NUM> to pass through the gap but providing a degree of grip on the body.

As shown in <FIG>, drive wheel <NUM> rotates in an anticlockwise direction while drive wheel <NUM> rotates in a clockwise direction. The combination of these two rotations has the effect of drawing a preform through the gap <NUM>. The two drive wheels do not however rotate at the same rate, with, in the preferred arrangement shown in <FIG>, drive wheel <NUM> rotating at a significantly lower rpm than that of guide wheel <NUM>. A preferred ratio of rotation of drive wheel <NUM> to drive wheel <NUM> is of the order of <NUM>:<NUM>.

The effect of this differential in rate of rotation of the two drive wheels is that drive wheel <NUM> exerts a considerably greater grip on the body <NUM> of the preform so that it acts to rotate the preform in an anticlockwise direction as the preform passes through the gap <NUM> between the two drive wheels. By this means a handle <NUM> of a preform which is in a leading position as the preform enters the gap <NUM>, is rotated until it contacts the right-hand lower rail 32b (as seen from above in <FIG>). To allow for this rotation of the handle a gap <NUM> is provide in the left-hand lower rail.

It will be understood that the anticlockwise rotation induced by drive wheel <NUM> 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 34A approach the escapement <NUM> in the preferred orientation with the handles in the trailing position.

The escapement <NUM> controls the feeding of the handle oriented preforms to the feeder wheel <NUM> as described above, retaining the trailing orientation of the handles as induced by the mechanism 34A. As for the first arrangement above, at the instance that a preform arrives at the pick of position <NUM>, a pair of opposing actuators (not shown) located under the pick off position <NUM>, simultaneously briefly close on, and then release, the preform handle <NUM> to fix its orientation relative the gripper <NUM> which, also at that instant engages with the neck <NUM> 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>. 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>), 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 heat shields, and for correctly placing the preform and the handle into the stretch-blow-moulding die.

With reference now to <FIG>, in this further preferred arrangement of a handle orientation mechanism 34b, injection moulded preforms <NUM> 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 <NUM> and <NUM>. The rollers <NUM> and <NUM> are so spaced as to allow the body <NUM> and handle <NUM> of each preform to drop through the gap between them but retain the wider diameter of the projecting collar below the neck <NUM> of the preform. The rollers <NUM> and <NUM> are mounted above a pair of spaced apart guide rails <NUM> and <NUM> (as best seen in <FIG>) 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 <NUM> and <NUM>, the handles <NUM> 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 <FIG> and <FIG>. 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 <NUM> 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 main support rails <NUM> and <NUM>, 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 <NUM> and <NUM> located on either side of a median vertical plane between the support rails. The flutes <NUM> of the auger screws are sized so as to capture between them the necks <NUM> 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' rotation.

Generally coextensive with the length of one of the auger screws, (in the arrangement shown in the drawings, auger screw <NUM>), the main support rail <NUM> is provided at its underside with a friction strip <NUM> (as best seen in the enlargement inset of <FIG>). This friction strip <NUM> projects slightly into the gap between the main support rails <NUM> and <NUM> 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 <NUM> is a gap in the guide rail <NUM>. Any rotation of an already trailing handle, will only force the handle into engagement with the opposite guide rail <NUM>, and remain trailing. But, as can be seen from the enlarged inset of <FIG>, 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 <NUM>) until these handles also are arrested from further rotation by the opposite guide rail <NUM>. From here as can be seen from <FIG> and <FIG>, the preforms, all with handles trailing, proceed down the main support rails <NUM> and <NUM> with the handles constrained between the now continuous guide rails <NUM> and <NUM> until they reach the final orientation operation at the feeder wheel <NUM>.

As well as spacing and rotating preforms as they pass between the auger screws <NUM> and <NUM>, the rotation rate of the auger screws is such as to deliver a preform to the feeder wheel <NUM> 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.

Referring now to <FIG> and <FIG>, a first rotating transfer system <NUM> is positioned adjacent the feeder wheel <NUM> with a continuously rotating carrier <NUM> of the first rotating transfer system <NUM> and the feeder wheel <NUM> contra-rotating one to the other.

The rotating carrier <NUM> of the first rotating transfer system <NUM> includes, in this embodiment, four opposing support arms <NUM> extending radially from a fixed centre of rotation <NUM> to rotate about a vertical axis <NUM>. Each end of the arms carries a first pick and place apparatus <NUM>. Each first pick and place apparatus <NUM> includes a linear guide <NUM>, a housing <NUM> which is rotatably mounted to the outer end of the support arm <NUM>, enabling rotation of the housing <NUM> about a vertical axis <NUM>. A two-fingered gripper <NUM> is mounted to a rotary actuator <NUM> supported by vertical plate <NUM> at an outer end of a free sliding element <NUM> of the linear guide <NUM>. The gripper fingers <NUM> are centred on a gripper effective vertical axis <NUM>, with the gripper able to be rotated about the horizontal axis <NUM> of the rotary actuator <NUM>.

A fixed horizontal cam plate <NUM> is mounted at a level below the rotating carrier <NUM> so that its centre is coincident with the vertical axis <NUM> of the rotating carrier. The perimeter edge <NUM> of the cam plate <NUM> forms an outer cam surface <NUM> and its upper surface <NUM> is provided with a cam channel <NUM> which is inboard of the perimeter edge <NUM> and the outer cam surface <NUM>.

The housing <NUM> of the linear guide <NUM> is provided with an outrigger arm <NUM> extending radially from the centre of rotation <NUM> of the linear guide <NUM>. The outer end of the outrigger arm <NUM> supports a first cam follower <NUM> locating in the cam channel <NUM>. The free sliding element <NUM>, adapted to reciprocating linear motion in a horizontal plane, is provided with a second cam follower <NUM> with the free sliding element <NUM> biased by springs <NUM> to maintain contact between the second cam follower <NUM> and the outer cam surface <NUM>.

The cam channel <NUM> and outer cam surface <NUM> are arranged so that as a first pick and place apparatus <NUM> rotates past the preform pick off position <NUM>, the rotation of the rotating carrier <NUM>, combined with the loci of the first and second cam followers <NUM>,<NUM> causes the gripper <NUM> to be both reciprocatingly extended and retracted, and rotated relative the arm <NUM>. The gripper motion is such that at the approach to the preform pick off position <NUM>, the free sliding element <NUM> and thus the gripper <NUM> is extended followed by rotation of the linear guide <NUM> and gripper <NUM> in retrograde or negative direction relative to the direction of rotation of the rotating carrier <NUM>.

At the instant a preform <NUM> arrives at the pick off position <NUM> after its approximate orientation, so that the handle <NUM> of the preform is trailing but not yet fixed, the extending movement of the gripper <NUM> through the first cam follower <NUM> against the outer cam surface <NUM>, brings the gripper effective axis <NUM> into coincidence with the central axis of the preform. At this instance also, a pair of opposing actuators located under the pick off position <NUM> simultaneously briefly close on, and then release, the preform handle <NUM> to fix its orientation relative the gripper <NUM> which, also at that instant engages with the neck <NUM> of the preform. The gripper <NUM> is then rotated positively to carry the preform <NUM> clear of the supporting short rail <NUM> and away from the pick off position <NUM>.

This combination of reciprocating rotation and extension and retraction of the gripper <NUM> compensates for the divergence of the loci of the supporting tooth formation <NUM> of the feeder wheel <NUM> and the rotating carrier <NUM> 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 <NUM> and the rotating carrier <NUM>.

With reference now to <FIG>, rotation of the rotating carrier <NUM> brings a preform <NUM> retained in a gripper <NUM><NUM> to the preheating stage <NUM> as was shown in <FIG> of the machine <NUM>. Because the preheating of the preforms is conducted with the preforms inverted from their initial position at the pick off position <NUM>, that is, with the neck <NUM> upward, the rotary actuator <NUM> at the end of the free sliding element <NUM> rotates the grippers <NUM> and the preforms through 180degree during their transit between pick off position <NUM> and the transfer to a preheating transport system <NUM>. The effect of this rotation is that the handle <NUM> of the preform is now "leading" with respect to the direction of rotation of the rotating carrier <NUM>, instead of trailing as it was at the pick off position <NUM> as could be seen in <FIG>.

The preheating transport system <NUM> is also in continuous movement and comprises a loop rail system <NUM> with proximate and distal rotating guide wheels <NUM> and <NUM> respectively at either end of the loop. A plurality of preform supporting mandrels <NUM> are adapted to move around the loop rail system <NUM>, 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 <NUM>,<NUM> by nesting in niches <NUM> of the guide wheels. As well as travelling around the loop rail system <NUM>, the mandrels <NUM> are continuously rotated about their vertical axes.

Preheating of the preform <NUM> is required for the body <NUM> 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 <NUM> and the neck <NUM> which retain their as injection moulded form in the blown container shown in <FIG>, must be protected from excessive heat as the preform moves through the preheating stage. For this reason, as shown in <FIG>, a preform supporting mandrel <NUM> is provided with a heat shield <NUM> comprising a channel <NUM> rising from a cylindrical collar <NUM> in which the handle <NUM> is protected while the neck <NUM> is protected by its insertion into the cylindrical collar <NUM> of the mandrel.

It may be noted that the patterns of the outer cam surface <NUM> and that of the cam channel <NUM> of the first rotating transfer system <NUM> as shown in <FIG>, near the pick off position <NUM> differ from those at the approach to, and following the preform transfer to preheating position <NUM>. This reflects the difference in movements required of a gripper <NUM> as it steers the preform into the position in which the vertical axis of the preform becomes aligned with that of the cylindrical collar <NUM> of the mandrel <NUM> and the handle <NUM> is aligned with the heat shield channel <NUM>. At the instant these axes are aligned and the handle <NUM> of the preform is aligned between the side elements of the channel <NUM>, a cylindrical plunger <NUM> within the collar <NUM> rises into the neck <NUM>, 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 <NUM> and the proximate guide wheel <NUM> are in continuous contrarotation. This complex movement is again made possible by the combination of the rotation of the arm <NUM> and the rotation and linear movements of the free sliding element <NUM>, and thus of the gripper fingers <NUM> of the first pick and place apparatus <NUM>.

Thus the transfer of a preform from the gripper of the first transfer system <NUM> to a preform supporting mandrel <NUM> 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.

As best seen in <FIG> and <FIG>, banks <NUM> of heating elements <NUM> are positioned along each of the straight sections of the loop rail system <NUM>. Graded hot air <NUM> is drawn across the path of the preforms <NUM> by extractor fans <NUM>. To prevent excessive heat build-up of the cylindrical collar <NUM> and the neck <NUM> of the preform in the collar, a cooling air stream <NUM> is directed at the collars.

As a mandrel <NUM> and preform <NUM> are rotated away from the transfer-to-preheating position <NUM> by the proximate rotating guide wheel <NUM>, the mandrels supported in the chain of the preheating transport system <NUM> travel along the first straight section <NUM>, around the distal rotating guide wheel <NUM> and back along the second straight section <NUM> to arrive at a transfer-from-mandrel position <NUM>. While traversing these straight sections, the mandrels are rotated about their vertical axes by a gear <NUM> of the mandrel engaging with chain <NUM> to evenly expose the bodies of the preforms to heat from the banks <NUM> of heating elements <NUM>. The heating elements <NUM> 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 <NUM> at both the transfer to preheating position <NUM> and at the transfer from mandrel position <NUM> is critical to allow the respective first and second transfer systems to insert and extract a preform handle from the channel of the mandrel's heat shield. These heat shield orientations with respect to the periphery of the proximate guide wheel <NUM> 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 98a fixed to the mandrel. As a mandrel approaches the transfer-from-mandrel position <NUM>, cam followers 98b and 98c engage with guide channels to rotate the mandrel into the required orientation. During transit about the periphery of proximate guide wheel <NUM>, the cam followers 98b and 98c 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 <NUM>.

With reference now to <FIG>, a second rotating transfer system <NUM> operates to transfer preforms <NUM> from the preheating transport system <NUM> to a stretch blow moulding die assembly <NUM>. The stretch blow moulding die assembly <NUM> comprises of four stretch blow moulding dies <NUM>, two of which can be seen in the truncated view of the machine in <FIG>. In the present embodiment, four radially disposed stretch blow moulding dies <NUM> rotate continuously about a common centre <NUM>.

The second rotating transfer system <NUM> is of similar configuration to that of the first rotating transfer system <NUM> described above. That is, it includes a cam plate <NUM>, also provided with an inboard cam channel <NUM> and an outer cam surface <NUM> around its periphery.

In this instance, second rotating transfer system <NUM> includes two, rather than four, continuously rotating opposing radial arms <NUM>, each of which carries a second pick and place apparatus <NUM>. Again, similar to the first pick and place apparatuses <NUM> of the first rotating transfer system <NUM> above, each includes a linear guide rotatably mounted to the respective outer end of the radial arm <NUM>, 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 <NUM>, while a second cam follower of the free sliding element of the linear guide remains in contact with the outer cam surface <NUM> by means of a spring.

Preforms still retained in preform supporting mandrels <NUM> arrive back at the rotating proximate guide wheel <NUM> of the preheating system and approach the transfer-from-mandrel position <NUM>, and are rotated into the required orientation of the heat shield as explained above. The cylindrical plunger <NUM> of a mandrel <NUM> approaching the transfer-from-mandrel position <NUM>, lifts the preform so that the neck is clear of the cylindrical collar <NUM> to allow the gripper of the second rotating transfer system <NUM> to engage the preform by the exposed neck <NUM>. Again, it is the motion of the gripper induced by the combination of rotation of the radial arm <NUM>, the rotation of the linear guide and linear movements of the free sliding element supporting the gripper as controlled by the cam channel <NUM> and outer cam surface <NUM>, which allows the preform and its handle to be smoothly removed from the preheating transport system <NUM>.

As one rotating radial arm <NUM> of the second rotating transfer system <NUM> approaches and removes a preform from the preheating transport system <NUM>, the opposite radial arm approaches the die loading position <NUM>. During its rotation from the transfer-from-mandrel position <NUM> to the die loading position <NUM>, the rotary actuator of the second pick and place apparatus <NUM> 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> shows both a rotating arm <NUM> and a stretch blow moulding die <NUM> approaching the die loading position <NUM>).

Stretch blow moulding dies of the die assembly <NUM>, are in the form of two die halves <NUM>, one of which is shown in <FIG>. Die halves <NUM> are hinged together about a vertical axis <NUM> in the manner of a bivalve, and with the hinge supported from a central structure <NUM> of the die assembly <NUM> in a typical arrangement for radial stretch-blow-moulding machines. The face surface <NUM> of the die half shown in <FIG> has been shaded to highlight the die cavity <NUM> for the body <NUM> and integral handle <NUM> of the preform. As is common in the stretch-blow-moulding of containers, the neck <NUM>, which remains unaltered in the stretch-blow-moulding process, projects out of the die when closed.

Referring again now to <FIG>, as stretch-blow-moulding dies <NUM> approach the loading position <NUM> the die halves open symmetrically about a bisecting radial line <NUM> passing through the centre of rotation <NUM> and the vertical axis <NUM> of the die hinge <NUM>, in preparation for receiving a preform. It may noted from <FIG> and <FIG>, that the rotation centres of the second rotating transfer system <NUM>, the proximate rotating guide wheel <NUM> of the preheating stage and that of the stretch-blow-moulding die assembly <NUM>, lie along a straight line <NUM>.

As an opened die <NUM> approaches the die loading position <NUM> lying on the straight line <NUM>, a radial arm <NUM> with a preform retained in the gripper of the second pick and place apparatus <NUM> also approaches the loading position. As the bisecting radial line <NUM> of the die halves <NUM> becomes coincident with the straight line <NUM>, the movements of the second pick and place apparatus <NUM> has brought the gripper effective vertical axis and thus the vertical axis of the preform into coincidence with the axis <NUM> 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 <NUM>. While the die halves close and the paths of the die <NUM> and the end of the rotating arm <NUM> begin to diverge, the rotation and extension of the gripper, still holding the neck <NUM> 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>, that the curved section of the handle <NUM> of the preform is nested in a constricting cavity <NUM> of the die which ensures that the handle is not distorted, nor the region between the junction points <NUM>,<NUM> 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 <NUM> closed, stretch-blow-moulding of the container proceeds and the die <NUM> loaded at the die loading position <NUM> rotates towards the die unloading position <NUM> as shown in <FIG>.

A third rotating transfer system <NUM> is located adjacent the stretch-blow-moulding die assembly <NUM>, and is configured in similar manner to that of the first and second rotating transfer systems <NUM>,<NUM> described above. As for the second rotating transfer system <NUM>, the third rotating transfer system <NUM> includes opposing radial arms <NUM> at the ends of each of which is a third pick and place assembly <NUM>. 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 <NUM> is controlled by a combination of the rotation of the opposing radial arms <NUM>, the linear movement of the free element of the linear guide and the two cam loci.

As the stretch-blow-moulding die <NUM>, now containing a finished container <NUM>, nears the die unloading position <NUM> lying on the line <NUM> joining the centres of rotation of the stretch-blow-moulding die assembly <NUM> and of the opposing radial arms <NUM> 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 <NUM> from the die <NUM>.

The third rotating transfer system <NUM> continuous to rotate, tanking the container <NUM> held by the gripper <NUM> into a discharge channel <NUM>, with the base of the container passing over a guide rail <NUM>. Guide rail <NUM> transitions from concentricity with the third rotating transfer system to concentricity with a rotating two-tiered outfeed wheel <NUM>. As the container <NUM>, now in the discharge channel <NUM>, reaches a release position <NUM> lying on the line <NUM> joining the centres of rotation of the third rotating transfer system <NUM> and that of the outfeed wheel <NUM>, the gripper <NUM> releases the neck and retracts. At the same time a scalloped indentation 172a of the rotating outfeed wheel captures the body of the container feeding it into a discharge channel <NUM>. As containers follow the path of the gripper <NUM> and then a path determined by the outfeed wheel <NUM>, the base of the container receives cooling air from orifices <NUM> in guide rail <NUM>, backpressure from accumulating containers in the discharge channel <NUM> force containers to drop into a container receiving bin <NUM>.

The operation of the machine <NUM> 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>, is produced from that region of the preform below the lower junction point of the handle.

<FIG> 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>, banks <NUM> of heating elements <NUM> are positioned along each of the straight sections of the loop rail system <NUM>. Graded hot air <NUM> is drawn across the path of the preforms <NUM> by extractor fans <NUM>. To prevent excessive heat build-up of the cylindrical collar <NUM> and the neck <NUM> of the preform in the collar, a cooling air stream <NUM> is directed at the collars.

In a preferred form each bank <NUM> comprises a module <NUM>. The modules <NUM> are arranged sequentially around the conveyer <NUM> as illustrated in <FIG>.

In a preferred form a processor <NUM> in conjunction with memory <NUM> executes a program for control of the heating elements <NUM> of the modules <NUM>.

In a particular preferred form each element <NUM> of each module <NUM> is controlled individually by the processor <NUM>.

In an alternative preferred form of the elements <NUM> are controlled as a group based on height - so the top most elements <NUM> of the modules <NUM> are controlled to a predetermined temperature together whilst the next down in height elements 109B are also controlled together to a predetermined temperature - and so on down to elements <NUM> at the lowest level.

In addition, the processor <NUM> controls the speed of rotation of motor <NUM> in order to control the continuous speed of the preforms <NUM>.

A temperature sensor <NUM>, in one form an infrared temperature sensor provides environment temperature sensing which is utilised by processor <NUM> to modulate the degree of heating of all elements <NUM> 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 <NUM> and the integral handle <NUM> as shown in <FIG>.

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.

In a first preferred a preform <NUM> according to the invention as shown in <FIG> includes a finished neck portion <NUM> and a tubular hollow body portion <NUM> extending from below the neck portion. Similar to preforms of the prior art, the outer surfaces of the body portion <NUM> are defined by diameters centred on a central vertical axis <NUM>, so that the body portion <NUM> approximates a cylinder but with a decrease in diameters from the neck portion <NUM> to the closed end <NUM> of the preform.

The internal surfaces of the preform <NUM> include surfaces of the hollow body portion <NUM> which are not concentric with the outer surfaces. Preferably, as shown in <FIG>, cross sections of the internal surfaces of the preform <NUM> are circular and concentric in the neck portion <NUM> 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 <NUM> of the body of the preform.

Referring now to <FIG>, in a preferred arrangement, the mandrel <NUM> around which the preform <NUM> is injection moulded, comprises an upper region <NUM> 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 <NUM> of the mandrel extends from this upper region <NUM> to a depth equal to that of the neck portion <NUM> and is of circular cross section A-A as shown in <FIG> to form the concentric walls of the neck portion. The ovoid portion <NUM> of the mandrel depends from the first portion <NUM>, extending to the tip <NUM> of the mandrel.

Given the ovoid shape of the cross sections of the ovoid portion <NUM>, there is a short transition portion of the mandrel immediately below portion <NUM> forming the internal form of the neck portion, which transitions from the circular cross section A-A of portion <NUM> 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 <NUM> 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>, that both the outer surfaces of the body portion <NUM> of the preform and the ovoid portion of the inside surfaces as defined by the mandrel <NUM>, are tapering; that is, the diameters defining the external surface of the preform are decreasing from below the neck portion <NUM> to the bottom <NUM>, while similarly, the major axis <NUM> and the minor axis <NUM> of the cross sections of the ovoid portion <NUM> also decrease accordingly.

Referring still to <FIG>, the preform <NUM> of the invention further includes, as noted above, an integral handle <NUM> which forms a loop of material extending vertically from an upper junction <NUM> below the neck portion <NUM> to a lower junction <NUM> with the outer surface of the preform. The handle <NUM> is centred on and defines a central vertical plane <NUM> (lying in the plane of the paper) which contains the central longitudinal axis <NUM> of the preform.

The mandrel <NUM>, and thus the internal surfaces of the ovoid portion <NUM>, are so oriented relative the handle <NUM>, that major axis <NUM> of the ovoid cross section B-B lies in the central vertical plane <NUM>.

It can thus be seen from <FIG> and cross section B-B that the wall thicknesses of the preform <NUM> in that portion <NUM> 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 <NUM> of the ovoid cross section to minimum thicknesses at outer ends of the major axis <NUM>. Preferably, the ratio of maximum wall thickness to minimum wall thickness of the ovoid portion lies in the range of <NUM>:<NUM> and <NUM>:<NUM>.

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 <NUM> of a rectangular cross section blown container <NUM>, while the polymer walls of the preform from the region of minimum thickness is predominantly distributed towards the shorter side walls <NUM> of the blown container such as shown in <FIG>. It can be seen from <FIG> that the longer side walls <NUM> lie on either side of the central vertical plane <NUM> and thus the handle <NUM> so that the alignment of the major axis <NUM> with the vertical plane <NUM> 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.

With reference now to <FIG>, in this preferred embodiment not forming part of the claimed invention, the exterior surface <NUM> of the preform <NUM>, is of substantially cylindrical form. As for the first embodiment above, it too includes an integrally injection moulded handle <NUM>. In this embodiment, the internal surfaces <NUM> of the preform are consistently circular in section as shown in the two sample cross sections Figure 17A and Figure 17B. However, again as is clear from the two cross sections and the sectioned side view of <FIG>, there is a tapering of the internal surface <NUM> so that the wall sections, though concentric to the external surface, increase from a minimum thickness at the neck portion <NUM> of the preform to a maximum proximate its lower end <NUM>. 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.

In this further preferred embodiment not forming part of the claimed invention, a preform <NUM> as shown in <FIG>, is formed to significantly reduce the volume of material required to produce the containers shown in <FIG>. As in the embodiments above, the preform <NUM> includes an injection moulded integral handle <NUM>. Although in this embodiment, the neck portion <NUM> 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 <FIG>, 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 <NUM> of the preform.

As a further means of reducing the volume of material in the preform of this embodiment, the outer surface <NUM> below the neck portion <NUM>, also tapers towards the lower end <NUM>. 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.

With reference now to <FIG>, this preferred embodiment of a preform <NUM> 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 <NUM> as previously described, and, as in the first preferred embodiment above, the internal surfaces <NUM> of the preform are not consistently of circular section throughout the length of the preform. However, the external surfaces <NUM> of the perform are substantially cylindrical in form as in the second preferred embodiment.

Thus, although the external surfaces <NUM> are defined by circular cross sections, the internal surface <NUM> varies from circular in cross section from the neck portion <NUM> down to section A-A in <FIG>, to then transition to an ovoid section B-B as shown in <FIG>, approaching the lower end <NUM>.

A feature of this particular embodiment is that the wall thickness of the ovoid portion of the internal surface <NUM> 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.

The preform of this embodiment of a preform <NUM> shown in <FIG> 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 <FIG>, 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 <NUM>. Rather the wall thickness gradually increases from below the neck portion towards the lower end <NUM> 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>, preforms, including those of the present invention, are typically injection moulded in multi-cavity dies <NUM> in which the cavities <NUM> 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 <NUM> 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 <NUM>, one half of which is shown in <FIG> 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 <NUM> of the die half).

To be effective in biasing polymer material flow from different wall thickness areas of the preform towards designated regions of the 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 <NUM> driven into the cavities <NUM>. The injection nozzle <NUM> is then advanced into the injection pocket <NUM> and molten polymer forced through the runner system <NUM> to fill the spaces between the external surfaces of the cavities <NUM> and the mandrels <NUM> 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.

This further preferred embodiment of a preform not forming part of the claimed invention and shown in <FIG>, the preform <NUM> is provided with a wall thickness <NUM> in the region between the junction points <NUM> and <NUM> of the integrally injection-moulded handle <NUM> 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 <NUM> 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> and cross section AA of <FIG>, the centres of a portion of the cross sections (typified by section A-A) do not lie on the central axis <NUM> of the body of the preform, but are offset towards the handle <NUM>.

The effect is to "thin" the wall thickness in the region between the junction points <NUM> and <NUM> 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.

With reference to <FIG>, a preform <NUM> for stretch-blow-moulding the container <NUM> shown in <FIG>, is comprised of a neck portion <NUM>, a collar <NUM> and a body <NUM> extending from below the collar. As in the preform according to prior art shown in <FIG>, the preform <NUM> includes an integral handle <NUM> joined to the body <NUM> at first junction position <NUM> just below the collar <NUM> and a second junction position <NUM> along the length of the body.

The first cylindrical portion <NUM> of the body extending below the collar <NUM>, 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>.

But it can be seen firstly from a comparison between the preform <NUM> according to the present invention, and the preform of the prior art, that there is a significant reduction in diameter of the body <NUM> below the first cylindrical portion <NUM>.

Furthermore, it is clear that this second portion <NUM> of the body, between the reduction in diameter and the tangent line <NUM> with the bottom portion <NUM>, is not cylindrical but forms a portion of a narrow cone, with the base diameter <NUM> of the cone, that is its largest diameter, significantly smaller than the diameter of the first cylindrical portion <NUM>. 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>, the walls of the body <NUM> of the preform <NUM>, vary considerably in thickness. While the wall thickness of the neck portion <NUM> and the first portion <NUM> below the collar <NUM> are substantially of a constant thickness, that of the second portion <NUM> varies from a relatively thin wall section at the base diameter <NUM>, to a maximum thickness proximate the tangent line <NUM>.

The wall thickness of the bottom portion <NUM> is further varied, being reduced from the maximum thickness at the tangent line <NUM> to a minimum at the base of the bottom portion.

This thinning of the wall thickness in the region below the maximum diameter <NUM> of the second portion <NUM>, augments the reduction in material volume provided by the diameter reduction and the form of the second portion <NUM>.

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 <NUM> shown in <FIG>, to an average thickness of approximately <NUM>. 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.

With reference to <FIG> 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>, in a preferred form of the preform, a preform <NUM> includes a neck <NUM>, a body portion <NUM> and a handle <NUM>. The neck <NUM> has a threaded portion <NUM> and a locating ring <NUM>. 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 <NUM> shown in <FIG>, is fed into a blow moulding machine such for example as the machine <NUM> shown schematically in <FIG>, and blow moulded according to bi-axial orientation blow moulding techniques. During this process the neck <NUM> is held in a mandrel <NUM>, as shown in <FIG> of a transport system of the machine <NUM> in such a way as to prevent its expansion in the stretch blow-moulding die <NUM>.

The loop of orientable material forming the handle <NUM> has a generally uniform cross section from proximate the lower connection region <NUM> to a gradually widening cross section <NUM> approaching the upper connection region <NUM> with the cross section reaching and maintaining a maximum width proximate the upper connection region <NUM> as can be seen in <FIG>.

With reference again to <FIG>, integrally moulded first, second and third strengthening elements <NUM>, <NUM> and <NUM> are provided respectively at each of the upper connection region <NUM>, the lower connection region <NUM> and at the junction between the straight section <NUM> and the arcuate section <NUM> of the handle <NUM>.

The first strengthening element <NUM> at the upper connection region <NUM> comprises a curved strengthening element conforming generally in width and in cross section to the width and cross section of the widened portion <NUM> of the handle proximate the upper connection region. The curved strengthening element extends from a first separate connection region <NUM> on the body portion <NUM> of the preform (and on the blown container) below the upper connection region <NUM> and merges with the loop of orientable material proximate a first end <NUM> of the maximum width of the handle.

The second strengthening element <NUM> at the lower connection region <NUM> 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 <NUM>. The straight strengthening element extends from a second separate connection region <NUM> above the lower connection region <NUM> 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 <NUM> at the junction of the straight section <NUM> and the arcuate section <NUM> 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 <NUM> and the arcuate section <NUM> adjacent the junction. Respective outer ends of this further curved element merge with each of the straight <NUM> and arcuate <NUM> sections.

It should be noted that, in this instance, the width of the first strengthening element <NUM> is the same as that of the maximum width of the widened part <NUM> of the handle proximate the upper connection region <NUM>. It is this increased width of the first strengthening element <NUM> 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 <NUM>, <NUM> and <NUM> includes a web of orientable material within boundaries formed respectively between the body portion <NUM> of the preform and the first and second strengthening elements <NUM> and <NUM>, and between the third strengthening element <NUM> and the straight and arcuate sections <NUM> and <NUM>. Each web of orientable material is aligned with and extends equally in both directions from the central line <NUM> 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.

With reference to <FIG> 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>. In this instance the cross-section wall profile as shown in section AA and section BB is rotated <NUM> degrees as compared with the wall profile of <FIG>. 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.

With reference to <FIG> 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>. In this instance the cross-section wall profile as shown in section AA and section BB is rotated <NUM> degrees as compared with the wall profile of <FIG>. 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.

The above described embodiments of the injection-moulded preforms which the continuously rotating stretch-blow-moulding machine transforms into containers, may be categorized as irregular preforms in that each includes one or more elements which depart from those preforms according to the prior art adapted for forming symmetrical containers. Moreover of course, the preforms of this application differ from those of that prior art in having an integral handle. It may be noted here again that the integral handle as injection moulded with the preform, remains unchanged when it emerges after stretch-blow-moulding of the preform as an integral handle of the container.

In a first form of irregularity, with reference again to <FIG>, (Third Preferred Embodiment described above) there is a marked discontinuity in the cross sections of both the outer and the inner surfaces of the body of the preform. Thus, there is an upper portion immediately below the neck of the preform in which the outer and inner diameters are substantially identical to those of the neck portion. Those diameters however are significantly reduced for the lower portion of the body, interconnected by a short transition section.

As can be seen from the cross-section views AA and BB, in this embodiment of <FIG>, concentricity of the internal and external diameters about a central axis of the preform is maintained.

In another form of irregularity, with reference now to <FIG> (First Preferred Embodiment above), in this embodiment of the preform, although the inner shape of the preform remains concentric with the outer form, in that they are centred on the same vertical axis of the preform, the lower section BB (<FIG>) is of elliptical cross section rather than circular as is the case for the upper portion represented by section AA (<FIG>). This irregular wall thickness allows for a greater volume of material to be available for the wider side walls <NUM> of a container compared to the lesser volume required for the end walls <NUM> as can be seen from <FIG>.

Another form of irregularity was disclosed in the Sixth Embodiment above and depicted in <FIG>. In this embodiment the irregularity is found in the significant reduction of wall thickness of the body of the preform in the region between the two connection points of the handle as shown in the cross section AA of <FIG>. In this region, the centres of circular cross sections of the interior surface of the body of the preform are offset towards the side of the handle, from the centres of the circular cross sections of the outer surface of the body.

In preferred forms the integral handle of the preform, as noted above, the handle 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> 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.

A preferred system of injection moulding any one of the above described preforms will now be described with reference to <FIG>. 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>, for preforms <NUM> with handles <NUM>, only that section <NUM> below the handle can be formed in cavities <NUM> in the heated, fixed section <NUM> of the die <NUM>, with the neck <NUM> and handle <NUM> formed in much longer and more complex opposing half cavities <NUM> carried on the moving die section <NUM>. Again, the cores <NUM> to form the internal shape of the preforms <NUM> are fixed to the moving die section <NUM> and are located on the common axis of the cavities <NUM> 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 <NUM> and therefore require a longer delay before preforms have cooled and are sufficiently stable for stripping off the cores <NUM>. 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>, a robot <NUM> (only a portion of the arm of which is shown in <FIG>) is employed in the demoulding of the preforms <NUM>. The robot arm end effector <NUM> is fitted with an array <NUM> of vacuum cups <NUM>, equal in number and spaced according to the number and spacing of the cavities in the injection moulding die as shown in <FIG>. Towards the end of a mould cycle this array <NUM> of vacuum cups is poised above (or to the side of) the injection moulding die <NUM> 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 <NUM> and <NUM> of the die, and advances the vacuum cups <NUM> 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 <NUM> 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 <NUM> and the robot retracts the array <NUM>, and the preforms <NUM> 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 <NUM> and the moving side <NUM> 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 fall 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.

The continuous movement of previously injection moulded, non-symmetrical preforms from their initial feeding into the machine <NUM> 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 outfeed 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.

Claim 1:
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 an integrally injection-moulded handle portion extending radially; said method comprising
· controllably transferring an integral handle PET pre-form onto a continuously moving conveyor while maintaining a known orientation of the handle portion;
· securing the preform by its neck portion to the conveyor whereby the preform is transported by the conveyor continuous from a pre-form entry location to a pre-form exit location;
· at 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 conveyor 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,
wherein the preform comprises an open neck portion and a hollow body extending from the neck portion; at least a portion of the walls of the hollow body varying in thickness, characterized in that cross sections of at least a portion of inner surface of the hollow body are ovoid in section.