Abstract:
Apparatus for and a method of handling flexible tubes, for example in the production of a liner for a cargo container to provide a tubular attachment on the liner. A tube  16  in the form of a web of flexible material is drawn over a support  39  mounted on a carrier  29,30 , the support having a greater area than that of the opened-out tube and being tilted to the radial plane (FIG.  2 ) during the drawing action. The support is then moved to the radial plane (FIG.  4 ) so as to stretch the tube  16  in the region of the support whereafter the tube is cut from the web, in the vicinity of the support. The support  39  is moved to a further processing station (FIG.  8 ), carrying the cut off tube  16 , whereat the tube is released from the support  39  by tilting the support once more and withdrawing the support from the tube. The support is then returned to its initial position ready for another cycle of operation.

Description:
FIELD OF INVENTION 
     This invention relates to apparatus for handling a tube of flexible plasticsmaterial cut from a web of that material. The invention further relates to a method of handling such a tube, for the further processing thereof. 
     The apparatus and method of this invention are particularly concerned with the manufacture of container liners and will in the following be described essentially solely in relation to that manufacturing process. It is however to be understood that the invention is not limited to that manufacturing process and aspects of the apparatus and method may equally be used in other processes. 
     BACKGROUND OF THE INVENTION 
     Liners for cargo containers, such as ISO box containers, are well-known and widely used for the bulk transport of flowable products—for example granular materials including agricultural produce and chemicals. Such liners are usually made from plastics sheet material which is pre-formed into a tube, or from sheet material which is suitably folded and subsequently is seam-welded to make a tube. End panels for a liner are provided either by welding the plastics material in an appropriate manner or by bonding into the tube a separate end panel. Access openings are provided both for the loading and discharge of the liner, when in use, and such openings frequently are fitted with access pipes—for example for the introduction of the product into the liner. Further, suitable arrangements must be made for the suspension of the liner in a container. 
     The manufacture of such a container liner tends to be somewhat labour intensive. Typically, a web of the plastics material is supported adjacent a work-table and is drawn out over that work-table so that the required operations may be performed by operators reaching across the liner and using suitable tools, such as thermal welding apparatus. In view of the width of such a liner, these operations are not very easy to perform in the central region of the liner where, for example an access pipe must be bonded to the liner, around an access opening formed through the material of the liner. A high degree of skill is required to ensure the bonding process, such as thermal welding, is carried out efficiently to provide a reliable joint which will not fail in use. 
     SUMMARY OF THE INVENTION 
     The present invention stems from research into ways for facilitating the handling of a plastics material tube which is to form the access pipe of a completed liner, and so which must be cut from a web of flexible plastics material and then bonded to a liner, around an opening pre-formed therein. The access pipe may be made of relatively thin-wall plastics material and so is not self-supporting; this leads to particular difficulties in handling the tube both at the time of cutting a suitable length from the web and subsequently to shape and bond the tube to the liner, to form the access pipe. 
     According to one aspect of the present invention, there is therefore provided apparatus for handling a tube of flexible plastics material drawn and then cut from a web thereof, which apparatus comprises a disc-shaped support having a greater diameter than the internal diameter of the tube and over which the material is drawn, and a carrier for the support, in which apparatus the support is mounted on the carrier for movement between a first position where the support lies at an angle to a radial plane of the tube to permit drawing of the tube thereover and a second position where the support lies substantially in a radial plane of the tube so that the part of the tube in which is located the support is stretched over the support and so is held thereby. 
     According to a second and closely related aspect of the present invention, there is provided a method of handling a tube of flexible plastics material using a disc-shaped support having a greater diameter than the internal diameter of the tube when opened out and being adjustably mounted on a carrier for movement between a first position where the support lies at an angle to a radial plane of the tube and a second position where the support lies substantially in a radial plane of the tube, in which method the support is disposed at its first position, a length of the tube is drawn over the support from a web thereof, the support is moved to its second position so that the part of the tube in which is located the support is stretched over the support and so is held thereby, and the drawn length of the tube is cut from the web, adjacent the support. 
     By using the apparatus of this invention, or performing the method of this invention, it becomes possible to handle on an automated basis a tube of relatively flexible, or “floppy”, plastics material to form an access pipe for a container liner. Despite the nature of the plastics material, a required length of the tube may be cut from the web and then be transferred to a bonding station where the tube is bonded to the material of the liner, around an opening pre-formed in the liner, without the need for intervening manual operations. 
     The handling of the floppy tube is possible in view of the movement of the support between its first and second positions—the support should have an effective projected area of no greater than the area of the tube (when opened out into a circular shape) when the support is in its first position, but has an effective area greater than the area of the tube when the support is in its second position. Thus, the material may be drawn over the support relatively easily so as to have the support positioned within the tube adjacent one end thereof, when the support is in its first position, but the tube is held firmly, in its opened-out configuration, when the support is in its second position. 
     Preferably, the support is moveable to a third position inclined at an angle to the radial plane of the tube and beyond the second position with respect to the first position. In this case, the movement of the support from the first position may go through the second position to the third position before finally returning to the second position. Such “over-running” of the support by a few degrees ensures that the material of the tube is not unduly stretched locally when the support finally is in its second position, and that the support is properly located in the tube, in a radial plane, at the time the tube is cut from the web. 
     Conveniently, the carrier is mounted on a sub-frame, arranged for movement of the support from a loading position where the tube is drawn over the support, to a discharge position where a cut length of tube is subjected to a further processing step—for example, the cut length is bonded to a container liner under manufacture. 
     The support itself may be in two parts, having an auxiliary disc connectable co-axially to the support and selectively releasable therefrom. For example, an electromagnet mounted on the support or auxiliary disc may be provided to allow such connection and release. The auxiliary disc preferably has a diameter no greater than that of the support, but may be smaller. In the latter case, it is advantageous for the area of the auxiliary disc to be substantially the same as that of the tube, when opened out. 
     The tube cutter preferably acts on the tube at a position adjacent the support when in its second position. Such a tube cutter may comprise at least one blade arranged for rotational movement about the tube, so as to effect a circumferential cut through the tube. For a two part support, the cutter preferably acts to cut the tube between the two parts. Either an externally-acting cutter or a cutter arranged between the two parts of the support, to act internally of the tube, may be employed. 
     A gripper mechanism may be mounted for vertical movement on the carrier, which gripper mechanism is arranged for gripping an end portion of the tube and then to draw the tube over the support prior to the cutting of the tube. Such a gripper mechanism may have an annulus surrounding the support and provided with gripping fingers or other clamps, to grasp the end portion of the tube. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     By way of example only, one specific embodiment of tube handling apparatus constructed and arranged in accordance with the present invention and configured to perform a method of this invention, and certain modifications thereof, will now be described in detail, reference being made to the accompanying drawings, in which: 
     FIG. 1 is a diagrammatic end view on the embodiment of apparatus, with that apparatus in an initial setting ready to perform a tube handling cycle, of cutting a length of tube from a web and then bonding the cut length to a sheet of plastic material around an opening therein, so as thereby to form an access pipe for a container liner being manufactured from said sheet; 
     FIGS. 2 to  9  show successive steps in the tube handling cycle performed by the apparatus of FIG. 1; 
     FIG. 10 is an isometric view of the tube support shown in FIGS. 1 to  9 , and also of a tube-cutter, in a first position; 
     FIG. 11 is a view similar to that of FIG. 10 but in a second position; 
     FIGS. 12 and 13 are plan views on the assemblies of FIGS. 10 and 11, respectively; 
     FIG. 14 is a side view on part of the apparatus shown in FIGS. 1 to  9 ; 
     FIG. 15 is a detail view on the tube support and gripping arrangement used in the apparatus of FIG. 14; 
     FIG. 16 is a plan view on a modified cutter arrangement, provided within the tube support; 
     FIG. 17 is a perspective view on the cutter arrangement of FIG. 16; and 
     FIG. 18 diagrammatically illustrates the first, second and third positions of the support. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1, there is shown the embodiment of apparatus of this invention for performing a tube handling method, also of this invention. In addition, the drawings show part of apparatus for manufacturing a cargo container liner, so that an access pipe may be provided thereon, that access pipe being formed by the tube handling method described herein. 
     A reel  15  of folded-flat plastics material tube  16  is supported on a frame  17  having an upper work area  18 , and to which the tube  16  is fed during initial setting up of the apparatus. An overhead gantry  19  extends over the frame  17  as well as the work table  20  of an automated liner-manufacturing production line. There, a length of liner plastics tubular material is drawn out over the work table  20  in order that various manufacturing processes may be performed thereon, including the attachment of a length of tube  16  to form an access pipe for a finished container liner. Apart from this step, the manufacturing process for the liner forms no part of the present invention and will not be described in further detail here. 
     The gantry  19  has a track  22  along which runs a carriage  23 . An endless chain  24  is arranged alongside the track  22 , passing round a pulley  25  at one end of the track and round a drive wheel on the output shaft of an electric motor  26  at the other end. The carriage  23  is coupled to the chain so as to be moved along the track on operation of the motor, between a first position (FIG. 1) above the frame  17  and a second position (FIG. 6) above the work table  20 , at appropriate times during the performance of the method. 
     The carriage  23  includes a platform  27  suspended below the track  22  by bars  28 , the platform slidably mounting a pair of arms  29  and  30 , which also pass through guides  31  and  32  provided in the carriage, at the level of the track  22 . The two arms  29 ,  30  have respective toothed racks  33 ,  34 , each engaged with a respective driving pinion provided on the output shaft of an individually controllable motor  35 ,  36  mounted on the platform  27 . The lower ends of the arms  29 ,  30  are provided with articulated links  37 ,  38  coupling the arms to a disc-shaped support  39 , described in more detail below, at diametrically opposed locations. By appropriate driving of the motors  35 ,  36 , the support  39  may be moved between an inclined (first) position shown in FIGS. 1,  14  and  15  and a horizontal (second) position shown in FIGS. 4 and 9. 
     The arms  29 ,  30  together with guides  31 ,  32  and racks  33 ,  34  comprise a carrier for the support  39 . The carriage  23 , bars  28  and platform  27  carrying the motors  35 ,  36  and guides  31 ,  32  together comprise a sub-frame supporting the carrier and movable between a loading position (FIGS. 1 to  5 ) and a discharge position (FIGS. 6 to  8 ). 
     A gripper assembly  41 , comprising an annulus  42  from which depends a plurality of gripper fingers  43 , is suspended below the carriage  23  on legs  44 , for vertical movement. The annulus is of a greater diameter than the support  39  and platform  27 , so that the annulus may move thereover, a suitable drive arrangement including motors  45  engaged with the respective legs  44  being provided on the carriage to effect such vertical movement. Further actuators (not shown) for the fingers  43  are provided so that the fingers may be opened and closed, when required. 
     The support  39  has a main upper part  47  and an auxiliary lower part  48 , both parts being disc-shaped and having central aperture  49  extending therethrough. An electromagnet  48 A is provided in an upstand of the lower part  48  so that when energized the upper part  47  is held securely to the lower part, but when not energized, the upper part may be moved away from the lower part. Means (not shown) are provided to ensure accurate co-axial alignment between the upper and lower parts  47  and  48 , when held together by the electromagnet  48 A. Such means may comprise inter-engaging pegs and sockets on the two parts, with those pegs and sockets being given appropriate leads to facilitate inter-engagement. Alternatively, a servo-drive arrangement may be used to obtain registration between the-two parts. 
     The diameter of the upper part  47  is greater than the internal diameter of the tube  16  with which the apparatus is to be used, so that when the tube overlies the upper part  47  with that part in a radial plane of the tube, the tube is radially stretched over the upper part. However, by sufficiently inclining the support  39  at an angle to the axis of the tube, as shown for example in FIG. 3, the effective (projected) area of the upper part may be reduced to that of the opened-out tube, so that the tube  16  may easily be drawn from the reel  15  by the gripper assembly  41  to pass over the support, without the tube being stretched. 
     The diameter of the lower part  48  in general should not be greater than the diameter of the upper part  47 , and in the illustrated embodiment is essentially of the same diameter. The diameter of the lower part could be slightly smaller than that of the upper part and possibly even smaller than the diameter of the tube, when opened out. In this case, the tube will not be stretched when it overlies the lower part  48  so that there will be no tendency for the free end of the tube, following severing of the drawn length and which projects above the lower part resiliently to curl inwardly. In turn, this assists the gripping of the free end of the tube, by the gripper fingers  43 . 
     The work area  18  of the frame  17  supports a pair of concentric rails  51 , with the diameter of the inner rail being sufficiently large to accommodate the support  39 . A pair of carriers  52  are mounted on the rails  51  in a diametrically opposed relationship, each carrier having a cutting blade  53  slidably mounted thereon for movement in the radial direction. When the blades  53  are moved radially inwardly and the carriers moved around the rails  51 , a circumferential cut will be made around tube  16  between the two parts  47 , 48  of the support  39 , when located horizontally within the inner rail  51 . 
     Four rams  55  (FIGS. 10 to  13 ) are equi-spaced around the inner rail  51 , each ram acting in the respective radial direction. Each ram has a clamp jaw  56  at its radially inner end, whereby the lower part  48  of the support  39  may be clamped thereby, following the positioning of the support  39  on the work area  18  as shown in FIG.  11 . Further, each clamp jaw  56  is provided with a movable finger  57  the radially inner end of which may be moved generally vertically. For this purpose, an electromagnetic actuator may be provided on the jaw  56 , to cause the finger to rock about the horizontal axis. 
     The operation of the apparatus will now be described. A reel  15  of folded-flat plastics material tube  16  is placed on rollers  59  provided at the base of the frame  17  and the tube is then fed round a jockey roller  60  and through a roller nip  61  to the work area  18  at the top of the frame  17 , the tube being opened out into a generally circular form. During initial setting up, the motors  35 ,  36  are driven so that the support  39  (with the upper and lower parts  47 , 48  thereof secured together) lies at the angle shown in FIGS. 1,  2  and  14  and so has an effective area, projected in the vertical direction, of about the same area as (but not greater than) that of the opened-out tube. The gripper assembly  41  is lowered to the work area  18  and the fingers  43  operated so as to grip the upper marginal region of the tube  16 . This initial setting of the apparatus and tube is as shown in FIGS. 2,  14  and  15 , FIG. 1 showing the fingers in their open position, ready for gripping the tube. 
     The gripper assembly  41  is then pulled upwardly (FIG. 3) by motors  45 , drawing the tube  16  over the inclined support  39 . A suitable length of tube for the required access pipe of the liner is drawn from the reel  15 , by controlling the upward movement of the gripper assembly  41 . The motors  35  and  36  are appropriately driven to lower the support  39  down to the work area  18  of the frame  17  and, as the support reaches that area, the angle of the support is moved to and then slightly beyond the horizontal position by a few degrees, before being pulled back to the horizontal position (FIG.  4 ). 
     FIG. 18 diagrammatically shows the support in its first position I, its second position II and its third position III. 
     Once horizontal, the support  39  is clamped in that position by driving the rams  55  to engage the clamp jaws  56  with the lower part  48  of the support. The tube  16  is then cut between the upper and lower parts of the support  39 , by moving the blades  53  radially inwardly and driving the two carriers  52  for at least 180°, so that the blades  53  perform a circumferential cutting operation around the tube  16 . This severs the part of the tube drawn over the support from the main part of the web of the tube (FIG.  5 ). If stretching of the tube over the lower part of the support occurs, the cut free edge region of the tube will tend to spring inwardly. The movable fingers  57  on the clamp jaws  56  are operated so as to engage behind that cut edge and hold it against further inward movement. 
     The electromagnet of the support is de-energised and the upper part  47  is lifted slightly and then moved away from the lower part, by horizontal movement of the carriage  23  until the upper part overlies the work table  20  of the liner manufacturing production line (FIG.  6 ). The short length of tube  16  below the upper part  47  of the support is able to relax and so curls inwardly to form a flange  63 , with the adjacent tube extending over the upper part  47  of the support being stretched. 
     In FIG. 7, the upper part  47  of the support is shown lowered by the motors  35 ,  36  to engage a plastics material liner being manufactured on the work table  20 . A thermal welding arrangement such as an annular heater  47 A is included in the upper part  47  of the support  39 , but could instead be incorporated within the work table  20 , whereby the flange  63  is thermally welded to the liner on the work table. Other bonding technique could be used such as chemical welding or use of an adhesive. 
     As shown in FIG. 6, an annular blade  47 B may be mounted on the under surface of the upper part  47  of the support, to cut an opening through the plastics material liner being manufactured on the work table  20 , the flange being welded to that liner around the opening. 
     Once the welding has been completed, the upper part of the support is raised and tilted, as shown in FIG. 8, leaving the tube  16  bonded to the liner, so as to form an access pipe for that liner. In view of the flexible nature of the plastics material, the access pipe may fall away from the support  39 , whereafter the carriage  23  is moved back to overlie the frame  17  and be re-engaged with the lower part  48  of the support (FIG.  9 ). The rams  55  are moved slightly outwardly so that the fingers  57  may pull the cut edge of the tube outwardly, ready for re-engagement by the gripper assembly  41 . Following the lowering of the gripper assembly  41  and the gripping of the cut edge by the gripper assembly fingers  43 , the clamping jaw fingers are rocked upwardly to come free of the cut edge and the clamp jaws  56  are moved radially outwardly towards the inner rail  51 . The support is moved back to its tilted first position, returning the apparatus to the condition shown in FIG. 1, ready for the performance once more of the cycle of operation. 
     Referring now to FIGS. 16 and 17, there is shown an alternative cutter arrangement to replace that shown for example in FIGS. 10 to  13 . This alternative cutter arrangement is mounted on the lower part  48  of the support  39  and operates outwardly, from within the lower part. In this way, external cutter blades on the work area  18  can be eliminated. 
     A spider  65  is rotatably mounted on the lower part  48  of the support  39 , closely to overlie that support. The spider has four arms  66  each of which carries at its radially outer end an arcuate bar  67 . At each of the two ends of each bar  67  there is mounted a respective solenoid actuator  68 , the armature  69  of which projects radially outwardly. Releasably mounted on each armature  69  is a respective replaceable cutter blade  70 , whereby energisation of each solenoid causes all of the cutter blades  70  simultaneously to move radially outwardly, beyond the outer periphery of the lower part  48  of the support  39 . 
     An annulus  72  is mounted on four pillars  73  on the lower part  48  and serves to connect to the upper part  47  of the support  39 , for example by means of further electromagnets, as discussed above. Further, the upper part  47  may include a registration ring (not shown) to ensure correct axial alignment of the upper and lower parts  47  and  48 . 
     As shown in the drawings, each arm  66  is cut away adjacent its respective bar  67 , to permit the partial accommodation of a pillar  73 . Thus, the spider  65  may move through slightly less than 90degs, the movement being limited by the pillars  73 . A drive mechanism (not shown) may be provided for the spider, such as a stepper motor. Power for such a motor and also for the solenoid  68  may be supplied from the upper part of the support  39 , when the upper and lower parts are connected together. 
     In this arrangement, the diameter of the lower part  48  advantageously is substantially equal to, or smaller than, the diameter of the tube, when opened out. Thus, the diameter of the lower part will be less than that of the upper part. Equi-spaced around the periphery of the lower part  48  are eight upstanding tabs  74 , arranged so as not to be contacted by the projecting blades of the spider. Those tabs serve to support the free end of a tube, following the severing of a drawn length of the tube and the subsequent removal of that drawn length, away from the lower part  48 . By supporting the free end of the tube, the engagement of that free end by the gripper fingers  43  is much facilitated. The tabs  74  could be mounted for movement generally in a radial direction, to offering of the free end of the tube to gripper fingers  43 .