HEAT SHRINKING APPARATUS

Abstract: Heat shrinking apparatus to shrink the plastics skirt of a tamper-proof cap to a bottle or like container. The apparatus comprises a conveyor (120), a pair of opposed belts (89) having longitudinal parallel runs on each side of the conveyor (120) to engage opposed sides of the periphery of a line of bottles, and a driving arrangement to drive the opposed belts at different speeds to rotate the bottles as they pass through the apparatus. A hot air or gas burner (57, 60) feeds a plurality of nozzles (7) positioned adjacent either side of the line of bottles to concentrate hot air or gases against the skirts of the cap. Height adjustment is provided to raise or lower the belts (89) and nozzles (7) to compensate for bottles of differenct sizes. The rotation of the bottles causes uniform subjection to the hot air or gases to improve the quality of the contact of the skirts of the caps against the bottles.

Description: HEAT SHRINKING APPARATUS This invention relates to heat shrinking apparatus and is concerned more particularly with apparatus suitable for applying heat to portion of the skirts of caps of plastic material so as to cause the material to shrink in size and engage firmly against the neck or other appropriate part of a bottle or other container to which the cap is applied. The invention is especially concerned with tamper-proof caps in which a band at the lower edge of the cap skirt is caused to shrink and engage tightly below an annular flange on the bottle neck. In general, apparatus according to the invention is characterised by the provision of at least two endless belts disposed to engage the peripheral surfaces of a line of bottles to advance them and simultaneously cause them to rotate, and means to apply heated air or gas to selected regions of caps on the bottles to cause shrinkage of selected zones of the caps on the bottle necks. In accordance with a feature of the invention means are provided to vary the speed of one driving belt, and further means are provided to vary the speed of a second driving belt relative to the first driving belt. According to another aspect of the invention means may be provided to adjust the height and also the lateral position of the means for applying heated air or gas so as to cater for bottles of different heights and shapes. According to a further aspect of the invention safety means may be employed whereby in the event of a cessation in the supply of air or gas the means fo heating the air or gas is discontinued. Thus electrical means may be employed for heating the air or gas, and at least one pressure sensitive switch may be employed so as to open the circuitry of the heating means if the pressure head causing the flow of air or gas should drop below a predetermined value. " Other aspects and features of the invention will be apparent from the following description of a preferred form thereof made in conjunction with the enclosed drawings. In the drawings: Figure 1 is an end view of heat shrinking apparatus. Figure 2 is a plan view of the apparatus, Figure 3 is an enlarged cross sectional view of a lower part of the apparatus showing drive mechanisms and hot air units. Figure 4 is an enlarged plan view of the apparatus. Figure 5 is a cross sectional view taken along the lines 5-5 of Figure 4, Figure 6 is a cross sectional view taken along the lines 6-6 of Figure 4 , and Figure 7 is a cross sectional view taken along the lines 7-7 of Figure 6. The heat shrinking apparatus illustrated in the accompanying drawings comprises, in summary, a rectangular frame over which a centrally positioned bottle conveyor runs longitudinally of the frame. A pair of vertically spaced belts having longitudinal parallel runs are provided on each side of the conveyor to engage opposite sides of the periphery of a line of bottles. A plurality of hot air nozzles are positioned on each side of the bottles to concentrate hot air against the necks of the line of bottles. The lower part of the frame includes means to drive and control the speeds of each pair of belts so that by introducing a speed differential the bottles are caused to rotate as they pass down the longitudinal axis of the frame. Means is also provided to raise and lower the belts to suit particular bottle sizes. The position and inclination of the hot air nozzles are also adjustable. A heater and ducting means are also housed in the lower part of the frame of the apparatus.- The apparatus is described in further detail hereunder. Referring more particularly to Figures 1 and 2 χ the drawings illustrate an apparatus comprising a rectangular box or frame 1 which is constructed of lengths of angle section steel welded together. The ό frame 1 is supported by four legs 37, one disposed at each lower corner of the frame. Each leg 37 is fitted with an adjusting screw 40 which screws into the leg and can be fixed by a lock nut. The adjusting screw 40 terminates in a head which rests on a pad 41 made of nylon or other suitable material. Thus the apparatus can be set up in a stable condition on a reasonably horizontal floor, with the upper surface of the frame truly horizontal, and some slight adjustment for height is also made possible. The frame 1 is surmounted by a rectangular base plate 2 over which is placed a tray 3 and these members are fixed firmly on the frame. The tray 3 has a small trough or gutter extending around its perimeter to drain away any liquid spillage which occurs during the use of the apparatus. At each corner of the tray 3 a flanged socket 6 is fixed in position. Each of the sockets 6 supports a corner post 4, the top of one of which is shown in detail in Figure 6. Each corner post comprises a length of stainless steel tubing, provided at its upper end with an internal collar 71 fixed in position by welding. Two elongated slots 73 are formed in the wall of the post below the collar, the slots 73 being diametrically opposite each other. Each of the corner posts 4 supports two clamp blocks, each block 8 has a suitable central aperture to receive the post 4 and a slot (not shown) is machined through into the bore to allow the block to be clamped onto the post by a clamping screw, not shown. One face 77 of the block 8 is recessed to receive a bearing support bracket 9. Holes are drilled and tapped in the clamp blocks 8, through the faces 77, to receive the ends of bolts 78 for attachment of the bearing support brackets. OMPI ^ RNAlXO The bearing support bracket 9 shown in Figure 4 comprises a rectangular bar 79, provided with holes to receive the bolts for attaching it to the clamp block 8, and a second rectangular bar 81 welded to the bar 79 and extending at right angles thereto. The bar 81 terminates in a block 82 which is welded to it and which is provided with a cylindrical hole 83 and a clamping bolt 85, whereby the block 82 can be clamped onto a cylindrical bar 91 of a belt guide, described later. The bar 79 of each bearing support bracket 9 has attached thereto a bearing 87, for a vertically extending shaft. It should be mentioned at this stage that the bearing support bracket described above is designed for use at the left-hand side of the apparatus. Other brackets 12, of somewhat similar construction but of opposite hand, are provided for similar use at the right-hand side of the apparatus. The apparatus includes a drive shaft 21 which extends upwardly through two of the bearings 87 and through pulleys 20 which are keyed to the shaft 21. The apparatus also includes a second shaft 22 which extends upwardly through the other two bearings 87 at the right-hand side of the machine, as viewed in Figure 1, towards the rear thereof, and through two further pulleys 20 keyed to the shaft 22. The two pairs of pulleys 20 on the shafts 21 and 22 are engaged by endless V-belts 89. At the side towards the medial longitudinal plane of the apparatus the belts 89 run over idler pulleys 28. The pulleys 28 are rotatably mounted on spindles which are fixed at opposite ends of a belt guide 10, shown in greater detail in Figures 4 and 5. As shown in these figures, the belt guide 10 comprises a length of stainless steel angle section 90 one flange of which is drilled near each end to receive the pivot pins for the idler pulleys, and the opposite flange of which V/JVH-i is cut away at the ends to accommodate the pulleys- The belt guide also includes two round stainless steel bars 91 which are welded to the partially cut away flange and extend at right angles to it in the same direction as the other flange of the angle section part 90. A shown in Figure 4, the bars 91 of the belt guides 10 are inserted into holes 83 in the blocks 82 of the bearing support brackets 9. Thus the belt guides 10 are disposed horizontally adjacent to the vertical longitudinal medial plane of the apparatus and the inner runs of the belts 89 are constrained to run along the inner surfaces of the belt guides 10 from the idler pulley 28 at one end to the idler pulley 28 at the other end. The outer run of each belt 89 extends partially round a further idler pulley 29 and is then reflexed about a tension pulley 48. The latter pulleys 28 and 48 are mounted on pivot pins fixed to an arm 46 which is in turn pivotally connected to a mounting plate 47. One end of the latter is welded to the belt guide 10 so as to extend horizontally and laterally outwardly therefrom. A helical tension spring 52 extends between a connecting pin on the arm 46 and one of a series of holes (not shown) in the member 47, so as to bias the arm 46 and maintain tension on the belt 89. The amount of tension can be varied by changing the hole to which the spring 52 is connected. As shown in Figure 3 the lower end of the driving shaft 21 is connected by a coupling 63 to the output shaft of a variable speed drive unit 58 supported within the frame 1 on a drive mounting bracket 13 which is bolted- to the frame 1. The bracket 13 comprises pieces of metal plate welded together with apertures to receive fixing bolts and with spaces to accommodate the drive train for the variable speed unit 58 and other items. The output shaft of the variable speed drive unit 58 carries a driving gear 23 which engages driven gear 53 attached to a sprocket wheel 25 both supported by an idler stud 54 mounted on bracket 13. Chain connecting sprocket wheel 25 to sprocket wheel 26 mounted on variator 59 gives rotation to shaft 22 on left hand side 5 of machine through coupling 64. The arrangement of support brackets, belt guides, pulleys and belts at the left-hand side of the apparatus is repeated at the right-hand side with some modifications. Thus the posts at the right-hand side carry further clamp blocks 8 which 10 are fixed to bearing support brackets 12 of opposite hand to the brackets 9. The brackets 12 support belt guides 50 which are shown in detail in Figures 4 and 5. As indicated, they are generally similar in nature to the left-hand belt guides 10 but differ in that the 15 cylindrical bars 92 are not welded directly to the angle section part of the bracket but are pivotally connected to lugs 83 welded to the bracket flange. Furthermore, as shown in Figure 4, the bars 92 are fitted with fixed collars 94 and helical compression springs 95 between the 20 lugs 93 welded to the bracket flange. By means of this arrangement the right-hand belt guide may be adjusted laterally against the resilience of the springs 95, to adjust the distance between the belts in the lateral direction, to provide for correct parallelism between the 25 belts, and to allow for bottle necks and caps of differing sizes. As with the left-hand side arrangement, endless belts 89 extend around driving and driven pulleys 20, idler pulleys 28, and a tensioning arrangement as 30 previously described. The rear pulleys 20 are mounted on a shaft 22 and the front pulleys 20 are fixed on a driving shaft 21 which, as shown in Figure 3, extends downwardly and is connected by a coupling 64 to the output shaft of a variable speed drive unit 59. The unit 35 59 is bolted to the drive mounting bracket 13 and its input shaft carries a driving sprocket 26 which is in the same plane as the driving sprocket 25 for the variable speed unit 58. An electric motor, not shown, is also fixed within the frame 1 and is connected by a couplinq, also not shown, to the input shaft of the variable speed drive unit 58. It will be evident that the driving arrangement described offers considerable flexibility. The design of the machine enables the two sets of belts to be disposed above the level of a conveyor 120 passing centrally through the central zone of the apparatus above the frame 1. Bottles are moved over the surface of the conveyor seriatim, by the engagement of the belts with the peripheral surface of the bottles. By adjusting the speed of the right-hand drive shaft to be different from that of the left-hand drive shaft the bottles are caused to rotate about their own axes as they advance. By manipulation of the controls of the two variable drive units the speed of the bottles through the apparatus can be controlled, and independently of this the number of rotations which each bottle makes in passing through the apparatus can also be adjusted. In order to accommodate for bottles of different heights the clamp blocks 8 can be raised or lowered on the posts 4 to ensure that the belts and belt guides are raised or lowered accordingly. The posts 4 also support further clamp blocks 5 one of which is shown in more detail in Figure 6. The block shown in this figure is designed for the left-hand side of the apparatus, the corresponding blocks 11 for the right-hand side of the apparatus being of opposite hand. In general, the blocks 5 and 11 are similar to the block but differ in that a diametrically extending hole 94 is provided. The clamp blocks 5 and 11 are fitted on the upper ends of the posts 4 and are held in position by O Pl ■ ZXAτx means of pins 121 which extend through the holes 94 in the clamp blocks, through the slots 73 in the posts 4, and through the lower end of threaded rods 30. The rods 30 extend upwardly through the fixed collars 71 at the 5 tops of the posts 4 and they engage within the correspondingly screw threaded bores of sprocket wheels 33. Thus the threaded rods 30 are suspended within the supper ends of the posts 4 by the engagement of the sprocket wheels 33 on the tops of the posts, and the 10 clamp blocks 5 are held in position by the engagement of the pins 121 through the screwed rods and are also constrained against rotation, due to the engagement of the pins with the sides of the slots 73. The four sprocket wheels 33 are engaged by a single endless chain 15 94, indicated by a dotted line in Figure 2, and this chain is held under tension by a sprocket wheel 34 carried on an arm 27 supported on the front right-hand pillar 4. Thus by movement of the chain 94, by hand or by the use of a suitable driving means not shown, all the 20 sprocket wheels 33 are rotated together and this causes the clamp blocks 5 and 11 to be raised or lowered simultaneously. Semi-circular retainers 35 are provided, one with each of the sprockets 33, to retain the sprocket chain in position. 5 The clamp blocks 5 and 11 are connected to adjusting plates 14, one of which is shown in detail in Figure 7. As indicated, each adjusting plate is provided with two elongated holes 95 through which bolts 96 can be engaged and screwed into holes in the block. The 0 arrangement enables the adjusting plate to be adjusted in the lateral direction. One end of each adjusting plate 14 is enlarged and is drilled, slotted and tapped to form a clamping head 97. The adjusting plates at the left- hand side of the apparatus support a mounting tube 15 5 which is a plain stainless steel tube extending vwirz ' * horizontally and longitudinally, outwardly of the posts 4. A second support tube 15 is supported in a similar manner by the adjusting plates 14 at the right-side of the apparatus. Each of the mounting tubes 15 is provided with six heat gun support brackets 16, one of which is shown in detail in Figure 7. It consists essentially of a block which is drilled, slotted and tapped to create a clamping block and is also drilled and tapped to allow a heat gun 57 to be bolted to it. The heat guns 57 are commercially available air heating devices and three are provided at each side, each being bolted to a support 16. The heat guns are each connected to the inlet of a heat distributing nozzle 7. Each nozzle 7 comprises a tubular inlet 98 leading into an outlet section 99 which diverges to a considerable extent in the horizontal direction and narrows in the vertical direction to a narrow slot. Internal vanes not shown are provided to promote uniformity of flow over the whole width of the nozzle. A guard plate also not shown is fixed to extend above the nozzle outlet over the full extent thereof. As shown in Figures 4 and 5 each of the mounting tubes 15 also carries two nozzle tie rod blocks 17 which are very similar to the heat gun support blocks 16. Each of them carries a nozzle tie rod 18. Each tie rod comprises a rod 102 which is screw threaded or welded to the supporting block, and the other end has welded to it a length of plate 103 extending to one side in a plane which is oblique to the axis of the rod 102. The angle is appropriate to allow the plates 103 of the tie rods to engage flat against the face of a guard plate of one of the heat distributing nozzles 7. As indicated in Figure 4 of the three heat distributing nozzles at one side are arranged in horizontal alignment with the adjacent edges of the guard plates 101 being connected together by OM?I joining straps 31, and the tie rods 18 are connected to the outer ends of the guard plates. Thus there is a unitary assembly at each side comprising the tube 15 with the heat guns 57, heat distributing nozzles 7 and the tie rods 18. The nozzles 7 provide a continuous elongated aperture through which heated air or other gas is emitted to the vicinity of caps in bottles which are passed through the apparatus by the belts 89. The height of the outlets of the heat distributing nozzles 7 can be adjusted by turning the tube 15 about its axis. To facilitate this action, the apparatus is provided at each side with an adjusting bracket 24 which is shown in detail in Figure 7. Each adjusting bracket 24 is welded to the block 14 to project laterally therefrom. The bracket 24 is provided at its opposite end with an offset block 106 drilled and tapped to receive a bolt 107. The end of the bolt 107 engages upon the upper surface of one of the adjusting plates supporting the tube 15. Hence, by slackening off the clamping screws of the adjusting plates the tube 15 can be turned fractionally by adjusting the screw 107. In this way fine adjustment of the height of the nozzles can be achieved. The apparatus further includes two pressure blower units 60 which are mounted within the lower half of the frame 1. The outlets of the * units 60 are connected to manifolds 42. Each manifold is fabricated from stainless steel plate and comprises a central chamber 108 with a single inlet tube 109 and three parallel outlet tubes 110. The outlet tubes 110 are connected- by flexible hoses 111 to the inlets of the heat gun units 57. Within each outlet tube 110 a circular damper plate (not shown) is mounte on a pivot pin extending diametrically to the plate and the tube 110. Thus, by adjusting the position of the damper plates the total rate of flow of air from the nozzle outlets can be OMW x∑ N - o ! controlled, and the flow may be made substantially uniform over the whole longitudinal extent of the machine, or a greater or reduced flow may be arranged if desired from the nozzles in one zone. The apparatus is provided with an electrical control box (not shown) which houses the electrical connections for the apparatus together with fuses and other electrical items and starting and stopping controls for the electric motor and for the operation of the hot air units 57 and the blowers 60 are mounted on the front panel of the control box. The box includes pressure • operated switches connected by appropriate air lines to the blower outlets or manifolds and operative to open the circuitry to the ' heat guns in the event that the pressure of air from the blowers falls below a predetermined amount. The apparatus described above provides a simple yet effective means for causing shrinkage of the skirts of plastics tamper-proόf caps that are positioned on bottles. The use of a pair of endless belts on each side of the line of bottles causes the bottles to rotate at a predetermined speed. The rotation of the bottles together with the proximity of the nozzles of the hot air blowers provides a continuous and uniform heating to the skirt of the caps and thus ensures that uniform shrinkage occurs. The drive mechanisms of the " endless belts ensure that the speeds of the belts can be varied to adjust the speed of rotation of the bottles. The speeds of the belts may also be varied to accommodate the speed of the main conveyor that transports the line of bottles through the apparatus. The apparatus has further advantages in that means are provided to simply and uniformly vary the heights of the endless belts to compensate for bottles of differing sizes. The blowers are inter-connected on «_»MΓI ^^NATIO opposite sides of the line of the bottles and the lateral and relative inclination adjusting means again compensates for bottles of differing sizes and heights. The endless belts may be driven by a single electric motor and any one of a number of suitable speed variators may be incorporated to provide the speed variation of the endless belts. As modifications within the spirit and scope of the invention may readily be effected by persons skilled in the art, it is to be undertood that this application is not limited to the details of the particular embodiment described by way of example hereinabove. OMH

Claims: CLAIMS 1. Apparatus to apply heat to a portion of a plastics cap of a container to cause said portion of a cap to shrink to engage firmly the container comprising at least two endless belts arranged to engage opposite sides of a line of containers and means to apply heated air or gas to the portions of said caps to cause shrinkage of said portions against said containers whereby the endless belts will cause each container of said line of containers to rotate as the containers advance through the apparatus. 2. Apparatus according to Claim 1 comprising means to vary the speed of one endless belt relative to the other endless belt. 3. Apparatus according to Claim 2 wherein means is provided to vary the speed of both belts. 4. Apparatus ' according to any one of the preceding claims wherein a pair of vertically spaced belts are provided on each side of the line of containers. 5. Apparatus according to any one of the preceding claims wherein means is provided to adjust the heights of the belts relative to the line of containers. 6. Apparatus according to Claim 5 wherein longitudinally extending belt guides are positioned behind each belt to support said belt against the line of containers. 7. Apparatus according to Claim 6 wherein a support assembly is provided on each side of the line of containers, said support assembly carrying the pair of endless belts and associated driving pulleys and the belt guides, the support assembly being mounted on spaced vertical pillars to be displaceable vertically relative to said pillars to vary the height of the belts to compensate for containers of varying heights. femE?ncg 8. Apparatus according to Claim 7 wherein each support assembly comprises a sprocket driven by an endless chain, rotation of the sprocket causing vertical displacement of the support assembly about the pillars. 9. Apparatus according to any one of the preceding claims wherein means is provided to adjust the height and lateral position of the means for applying heated air or gas to the containers. 10. Apparatus according to Claim 9.wherein a plurality of hot air or gas blowers are provided on each side of the 'line of containers. 11. Apparatus according to Claim 10 wherein the plurality of blowers are mounted on a longitudinally extending arm, the position of the blowers being adjustable laterally of said arm and the inclination of said blowers to said arm being adjustable. 12. Apparatus according to any one of the preceding claims wherein a conveyor is positioned centrally of the apparatus to advance the containers in a line longitudinally of the apparatus. 13. Apparatus according to any one of the preceding claims wherein electrical heating means is provided within the apparatus to supply hot air to the plurality of blowers. 14. Apparatus according to claim 13 wherein the apparatus is provided with safety means whereby in the event of a cessation of a supply of air the means for heating the air is discontinued. 15. Apparatus according to Claim 14 wherein a pressure-sensitive switch is employed to open the circuitry of the electrical heating means if the pressure causing the flow of air should drop below a predetermined value. OMPI 16. Apparatus substantially as described herein with reference to and as illustrated in the accompanying drawings. ^fSSmo

Inventors: HITZLER HERMANN, HITZLER, HERMANN
Applicants: CONTAINERS LTD, CONTAINERS LIMITED
Application year: 1984
Main classification: B65B53
IPC codes: B65B7, B67B5