GB1563137A

GB1563137A - Methd and machine for manufacturing carrier bags of heat-weldable material

Info

Publication number: GB1563137A
Application number: GB41901/76A
Authority: GB
Original assignee: Printex
Current assignee: Printex
Priority date: 1975-10-10
Filing date: 1976-10-08
Publication date: 1980-03-19
Also published as: FR2327085A1; DE2645560A1; IT1068684B

Description

(54) METHOD AND MACHINE FOR MANUFACTURING CARRIER BAGS OF HEAT-WELDABLE MATERIAL (71) We, PRINTEX, a Company organised under the laws of Belgium, of 62, Chausée de Vilvorde, Nederover-Hembeek, Belgium, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a method of and a machine for manufacturing bags of heatweldable plastics material which bags are provided with handles constituted by cutouts formed in the walls of the bag and which include reinforcements secured to the walls of the bag in the regions of the cut outs.

Methods are already in existence for placing these reinforcements in bags. In the case of bottom welded bags, the method involves stick- ing the reinforcements on the material constituting the bag before the formation of the bag, and in the case of side welded bags, the method involves cutting the reinforcements from heat-weldable material previously introduced between the layers of material constituting the bag and in welding the reinforcements to said layers either before or at the moment of formation of the bags. The known method of manufacturing bottom welded bags has various drawbacks the chief of which resides in the use of an adhesive for the securing of the reinforcements and in the difficulty of choosing an adhesive which is suitable for the plastics materials used.In addition, the machine for putting this method into practice can only be used for the manufacture of bags of the said type with adhesively secured reinforcements and, moreover, it comprises a complex sticking device which necessitates very precise control operations and requires frequent maintenance. As for the method of making side welded bags, although the drawbacks resulting from sticking of the reinforcements are avoided, it has the drawback that it can only be used to manufacture side welded bags which are in less demand than bottom welded bags, mainly due to the fact that they do not have gusseted sides.

The present invention aims to overcome thes drawbacks and to provide a method enabling the fitting of welded reinforcements in either bottom welded or side welded bags. The method according to the invention also has the advantage that it can be performed on a conventional bag-forming machine to which it suffices to join an accessory enabling the fitting of the said reinforcements.

According to this aspect of the invention, a method of manufacturing bags of heat-weldable plastics material, each of which bags is provided with handles constituted by cut-outs formed in the walls of the bag and which includes reinforcements secured to the walls of the bag in the regions of the cut outs, is characterised by the steps of moving in stepwise manner a continuous band of heat-weldable plastics material in two superimposed thicknesses in a direction parallel to the longitudinal axis of the band, momentarily separating the two thickneses from one another, cutting two reinforcements for a bag from heat-weldable plastics material and introducing them, during a step movement of the band, one above the other between the two thicknesses of material where the latter are separated from one another, welding each of these reinforcements, during a dwell period of the band, to the corresponding thickness of material, forming, during a dwell period of the band, the cut-outs constituting the handles where the reinforcements have been placed, and seaming and cutting the band transversely of its length, between two consecutive cut-outs, by effecting a welding of the two thicknesses of material for forming the bags.

The two reinforcements may be cut simultaneously from the heat-weldable plastics material at a location spaced from the band and then be introduced simultaneously between the separated thicknesses of the band material. The welding of the two reinforcements to the re spective thicknesses of the band material may take place in a single operation.

The invention also includes a machine for performing the method of the invention. Ac- cording to this aspect of the invention, the machine, which comprises means for moving the said band stepwise in a direction parallel to the longitudinal axis of the band, means for forming the cut-outs constituting the handles of each bag and means for seaming and cutting the band transversely of its length, between consecutive cutouts, by effecting welding of the two thicknesses of material constituting the band for forming the bags, is characterised in that the machine is provided with an apparatus for feeding and attaching said reinforcements, which apparatus comprises means for separating the superimposed thicknesses of the band, a platform turnable around an axis perpendicular to a plane in which the band moves and arranged so that a portion of the platform, in use, is situated between the two separated thicknesses of the band, this platform having zones distributed around its periphery each intended to receive in turn, when the platform is at rest, two reinforcements situated one above the other and on opposite faces of the platform and at which these reinforcements are immobilised relative to the platform during rotation of the latter, a device for cutting said reinforcements from at least one strip of material and for supplying two of the said reinforcements to one of said zones of the platform situated in a portion of the platform lying, in use, outside said thicknesses of the band, means for stepwise driving of the platform during stepwise movements of the band to bring said zones provided with reinforcements in turn to the locality where the reinforcements are applied to the thicknesses of said material, means for immobilising the reinforcements on the said zones of the platform during their transfer from the said cutting and supplying device up to the locality where they are welded and during the welding operation, and means for welding each of the said reinforcements to the corresponding thickness of material.

Preferably, the means for driving the platform is arranged to move the platform always in the same direction one step at a time.

Advantageously, the machine comprises a folding cone for folding a band of a single thickness of material into said band consisting of two superimposed thicknesses of material.

The invention also includes bags when made by the method of the invention or in the machine of the invention.

The invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a schematic perspective view, partly broken away, of a machine for carrying out the method according to the invention, and Figure 2 is a perspective view, on an enlarged scale, showing a detail of the machine of Figure 1.

The drawing illustrates a method of manufacturing bags from thermoplastics material, which bags are provided with handles 1 constituted by cut-outs 2 formed in the walls 3 and 4 of the bag and include reinforcements 5 secured to the walls of the bag in the regions of the cut outs. The method consists in moving stepwise a continuous band 6 of heat-weldable material, arranged in two superimposed thicknesses 7 and 8, in a direction parallel to the longitudinal axis of the band 6, in separating momentarily the two thicknesses 7 and 8 from one another, in cutting simultaneously two of the reinforcements S from heat-weldable plastics material in a region apart from the band 6, in introducing simultaneously, during a step movement of the band, the two reinforcements S between the two thicknesses 7 and 8 where they are separated from one another, with the two reinforcements situated one above the other, in welding each of these two reinforcements 5, in a single operation and during a dwell period of the band, to the corresponding thickness 7 or 8 of the band 6, in causing the band 6 to advance by one or more steps, in forming, during a dwell period of the band, the cutouts 2 constituting the handles in the regions where the reinforcements S have been welded to the band, and in seaming and cutting the band transversely of its length, between two consecutive cut-outs 2, by effecting the welding together of the two thicknesses 7 and 8 of the band material in order to form the bags.

For the purpose of producing the band 6 formed of the two superimposed thicknesses 7 and 8, it is advantageous to start from a band 6' of material of single thickness, which is easier to print than a band of double thickness. By forming a fold 9 parallel to the longitudinal axis of the band 6', the band 6 having the two thicknesses 7 and 8 is produced. For the manufacture of bottom welded bags, the fold 9 is advantageously formed so that the thickness 8 juts out in relation to the thickness 7, and the reinforcements 5 are introduced between the two separated thicknesses 7 and 8 of the band and fixed to the latter so as to be situated substantially equidistantly from the longitudinal edges 10 of the band 6. After the positioning and welding of the reinforcements 5, at 14, the part 12 of the thickness 8 which juts out in relation to the thickness 7 is turned back, at 11, on the thickness 7 and the welding of this tumed back part to the thickness 7 is effected, at 13, to form a tube. The welded joint is cooled, at 15, and then, at 16, a gusset 17 is formed along each of the longitudinal edges 10 of the band 6 from which the tube has been formed. The cutouts 2 forming the handles 1 are then made by perforating, at 18, the two thicknesses 7 and 8 of the band as well as the reinforcements which are welded thereto. The transverse cutting of the band 6 to form the bag is finally proceeded with, at 19, the band being in the form of a tube provided with gussets 17.This cutting takes place, at the same time as the welding of the bottom of the bag, in the region of the cutouts 2 constituting the handles of the preceding bag, either on a level with the reinforcements 5, or at a small distance from the latter.

For the manufacture of side welded bags, the band 6' is folded to constitute the band 6 having two strictly superimposed thicknesses 7 and 8, the latter are separated and the reinforcements 5, in pairs, are placed close to the free edges of the said thicknesses, the cut-outs 2 are then formed, whilst transverse cutting to form the bags is effected midway between the cutouts 2 of consecutive bags.

The machine for performing the method which is illustrated in the drawing and which is equipped to make bottom welded bags, comprises a folding cone 20 enabling the formation of the band 6 having two superimposed thicknesses starting from the single thickness band 6', a compensating device 21 enabling the continuous unwinding of the band 6 upstream of the said device and the stepwise moving of the band 6 downstream of the latter, means 22 for forming simultaneously the cut-outs 2 constituting the handles 1 of each bag and means 23 for performing the transverse cutting and welding to form the bags.

The machine is provided with a feed apparatus 24 for reinforcements 5 comprising a platform 25 turning around an axis perpendicular to the plane in which the band 6 moves and ananged so that a portion of the platform is situated between the two thicknesses 7 and 8 of material constituting the band. The platform 25 has, uniformly distributed around its periphery, zones 26 each intended to receive in turn, when the platform is stopped, two reinforcements situated one above the other on opposite sides of the platform 25, at which zones the reinforcements are immobilised relative to the platform during rotation of the latter.The apparatus 24 also comprises a feeding device 27 for reinforcements which, starting from a strip 28 of material, supplies two superimposed portions 29 of material constituting the said reinforcements opposite one of the zones 26 of the platform 25 which is situated in a portion of the platform lying outside the band 6. A stepwise driving means 30 for driving the platform 25 is arranged so as to move the latter always in the same direction (following the arrow 31) by one step, in order to bring the zones 26 provided with reinforcements 5 opposite the locality where the reinforcements are secured to the thicknesses 7 and 8 of material, each step movement of the platform taking place during a step movement of the band 6.The platform 25 includes means 32 for immobilising the reinforcements 5 relative to the platform 25 at the zones 26 after their transfer from the feeding device 27 and up to the locality where they are welded and also during the operation of welding the reinforcements 5 to the corresponding thicknesses 7 and 8 by means of welding means 33.

The feeding device 27 comprises means for supporting the strip 28 of single thickness material which is intended to constitute the reinforcements, a knife 34 for sectioning the strip 28 into two substantially equal parts 37 and 38, parallel to one of its longitudinal edges 35, guides 36 arranged to superimpose the two parts 37 and 38 of the strip, means 39 for the simultaneous stepwise driving of these two strip parts, a plate 40 situated downstream of the means 39 and intended to separate the parts 37 and 38 of the strip from each other so that, when they are driven, they dispose themselves on opposite sides of the platform 25 and a knife 41 movable transversely of the longitudinal axis of the strip parts 37 and 38.The knife 41 is arranged to cut off portions from the strip parts 37 and 38 fed to the opposite sides of the platform 25, which cut off portions are intended to constitute the reinforcements 5. The driving of the strip parts 37 and 38 in the device 27 and the separation of said portions take place when the platform 25 is at rest and when one of the free zones 26 of the platform is opposite the plate 40. The stepwise driving means 30 for the platform 25 is constituted by a jack 42 actuated by a mechanism, known per se, moving the platform 25 a fixed angular distance corresponding to the angular distance separating consecutive zones 26 of the platform 25 intended to receive the reinforcements 5.The control of the jack 42 is synchronised with the bag-forming machine so that the platform 25 is moved during movement of the band 6 of material intended to constitute the bags. The means 32 for immobilising the reinforcements 5 on the zones 26 of the platform 25 comprises a vacuum pump (not shown), and a distribution system 43 for pipes 44 connecting the vacuum pump to the zones 26. The pipes 44 lead to perforations 45 at the zones 26, these perforations 45 opening into the upper and lower faces of the platform in positions where they are covered by the reinforcements 5 delivered from the feeding device 27.When suction is applied by the distribution system 43, the reinforcements 5 are held on the platform 25, the distribution system 43 being arranged so that the suction is created in a predetermined zone 26 of the platform when the portions of material intended to constitute a pair of reinforcements are fed, on opposite sides of the platform, in the said zone 26.The means 33 for welding the reinforcements to the two thicknesses 7 and 8 of the material are constituted by two heating elements 46 situated on opposite sides of the two thicknesses 7 and 8 of the material and actuated by jacks 47, when the band 6 and the platform 25 are at rest, in opposite directions in order to grip and weld the thicknesses 7 and 8 of material to the respective reinforcements 5, the platform 25, situated between the said reinforcements serving as thermal insulation so that the two reinforcements are not welded at one another.

At the locality where the platform 25 is situated, the thicknesses 7 and 8 of the material of the band 6 are separated from each other by rods 48. Downstream of the platform 25, the part 12 of the thicknesses 8, is turned by means of a profiled rod 49 and this folded part 12 is welded to the thickness 7 In order to form the aforesaid tube. At the locality where this welding is effected, the thicknesses 7 and 8 of the material are separated from each other by a plate 50 serving as thermal insulation to prevent the welding of the thickness 7 to the underlying portion of the thickness 8. When the band 6 advances by a step, the welded joint which has just been effected to form the tube is placed under an air blowing device, supplied by a fan 51, for cooling the zone of the material heated during welding.At the following step, the formed tube passes through a device 52 enabling the formation of the gussets 17. The tube is then fed at the following step under the means 22 for forming the cut-outs 2 and the bag is finally formed by welding bars 53 constituting the aforesaid means 23 which weld and cut the bottom of the bag.

To form bags with side welds, it suffices to space the platform 25 away from the band 6 so that the reinforcements 5 are placed in the region of the free edges of the said band, to render inoperative those organs of the machine forming the tube and the gussets, to re-site the means 22 for forming the cutouts and to effect side welds for forming the bag by means of the welding bars 53.

It will be appreciated that the invention is not limited to the embodiments which have been described above and that modifications may be made to the latter without departing from the scope of the ensuing claims. Thus, in particular, provision may be made to associate the heating elements 46 welding the reinforcements 5 and the means 22 for forming the cutouts 2 so as to realise, in a single operation, the welding of the reinforcements 5 and the formation of the cut-outs 2.

WHAT WE CLAIM IS: 1. A method of manufacturing bags of heatweldable plastics material, each of which bags is provided with handles constituted by cut-outs formed in the walls of the bag and which includes reinforcements secured to the walls of the bag in the regions of the cut outs, characterised by the steps of moving in a stepwise manner a continuous band of heat-weldable plastics material in two superimposed thicknesses in a direction parallel to the longitudinal axis of the band, momentarily separating the two thicknesses from one another, cutting two reinforcements for a bag from heat-weldable plastics material and introducing them, during a step movement of the band, one above the other between the two thicknesses of material where the later are separated from one another, welding each of these reinforcements, during a dwell period of the band, to the corresponding thickness of material, forming, during a dwell period of the band, the cut-outs constituting the handles where the reinforcements have been placed, and seaming and cutting the band transversely of its length, between two consecutive cut-outs, by effecting a welding of the two thicknesses of material for forming the bags.

2. A method according to claim 1, in which the two reinforcements are cut simultaneously from the heat-weldable plastics material at a location spaced from the band and are introduced simultaneously between the separated thicknesses of the band material.

3. A method according to claims 1 or 2, in which the welding of the two reinforcements to the respective thicknesses of the band material takes place in a single operation.

4. A method d according to any of the pre- ceding claims, in which said band of material is derived from a band of single thickness by folding this band along a line parallel to its longitudinal axis to form said band of material in two superimposed thicknesses.

5. A method according to any of the preceding claims, in which said reinforcements are introduced between the two thicknesses of material and secured to the latter so as to be situated substantially equidistantly from the longitudinal edges of the band constituted by the two superimposed thicknesses of material.

6. A method according to claim 4 or claims 4 and 5, in which said folding line is disposed so that one of the thicknesses of superimposed material juts out with respect to the other thickness of material.

7. A method according to any of the preceding claims, in which, between the region where the reinforcements are introduced between the superimposed thicknesses of material and the region where the transverse cut is effected to form the bags, the free edges of the band are joined by welding, during a dwell period of the band, to form a tube.

8. A method according to claims 6 and 7, in which, prior to the welding of the free edges of the band to form said tube, said jutting out part of one thickness of the material is folded over the free edge of the other thickness of the material, after which said jutting out part is welded to said other thickness of material in such a way that these two parts are joined in regions substantially equally spaced from their free edges.

9. A method according to claim 7 or 8, in which, between the region where the tube is formed and the region where the transverse cut is effected to form the bags, a gusset is formed along each longitudinal edge of the tube.

10. A method according to claim 9, in which the weld joining the thicknesses of material to form said tube is cooled prior to forming said gussets.

11. A method according to any of the preceding claims, in which the transverse cut for forming a bag is performed in the proximity of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. At the locality where the platform 25 is situated, the thicknesses 7 and 8 of the material of the band 6 are separated from each other by rods 48. Downstream of the platform 25, the part 12 of the thicknesses 8, is turned by means of a profiled rod 49 and this folded part 12 is welded to the thickness 7 In order to form the aforesaid tube. At the locality where this welding is effected, the thicknesses 7 and 8 of the material are separated from each other by a plate 50 serving as thermal insulation to prevent the welding of the thickness 7 to the underlying portion of the thickness 8. When the band 6 advances by a step, the welded joint which has just been effected to form the tube is placed under an air blowing device, supplied by a fan 51, for cooling the zone of the material heated during welding.At the following step, the formed tube passes through a device 52 enabling the formation of the gussets 17. The tube is then fed at the following step under the means 22 for forming the cut-outs 2 and the bag is finally formed by welding bars 53 constituting the aforesaid means 23 which weld and cut the bottom of the bag. To form bags with side welds, it suffices to space the platform 25 away from the band 6 so that the reinforcements 5 are placed in the region of the free edges of the said band, to render inoperative those organs of the machine forming the tube and the gussets, to re-site the means 22 for forming the cutouts and to effect side welds for forming the bag by means of the welding bars 53. It will be appreciated that the invention is not limited to the embodiments which have been described above and that modifications may be made to the latter without departing from the scope of the ensuing claims. Thus, in particular, provision may be made to associate the heating elements 46 welding the reinforcements 5 and the means 22 for forming the cutouts 2 so as to realise, in a single operation, the welding of the reinforcements 5 and the formation of the cut-outs 2. WHAT WE CLAIM IS:

1. A method of manufacturing bags of heatweldable plastics material, each of which bags is provided with handles constituted by cut-outs formed in the walls of the bag and which includes reinforcements secured to the walls of the bag in the regions of the cut outs, characterised by the steps of moving in a stepwise manner a continuous band of heat-weldable plastics material in two superimposed thicknesses in a direction parallel to the longitudinal axis of the band, momentarily separating the two thicknesses from one another, cutting two reinforcements for a bag from heat-weldable plastics material and introducing them, during a step movement of the band, one above the other between the two thicknesses of material where the later are separated from one another, welding each of these reinforcements, during a dwell period of the band, to the corresponding thickness of material, forming, during a dwell period of the band, the cut-outs constituting the handles where the reinforcements have been placed, and seaming and cutting the band transversely of its length, between two consecutive cut-outs, by effecting a welding of the two thicknesses of material for forming the bags.

the cutouts constituting the handles of the preceding bag, this transverse cut being effected either level with or a short distance from said reinforcements.

12. A method according to any of claims 1 to 4, in which said reinforcements are introduced between the two thicknesses of material and are fixed to the latter so as to be situated in the vicinity of the free edges of said thicknesses, the transverse cut for forming the bags being made substantially midway between two consecutive cut-outs forming the handles.

13. A method of manufacturing bags of heat-weldable plastics material substantially as hereinbefore described with reference to the accompanying drawing.

14. A machine for carrying out the method claimed in any of the preceding claims, comprising means for moving the said band stepwise in a direction parallel to the longitudinal axis of the band, means for forming the cutouts constituting the handles of each bag and means for seaming and cutting the band transversely of its length, between consecutive cutouts, by effecting welding of the two thicknesses of material constituting the band for forming the bags, characterised in that the machine is provided with an apparatus for feeding and attaching said reinforcements, which apparatus comprises means for separating the superimposed thicknesses of the band, a platform turnable around an axis perpendicular to a plane in which the band moves and arranged so that a portion of the platform, in use, is situated between the two separated thicknesses of the band, this platform having zones distributed around its periphery each intended to receive in turn, when the platform is at rest, two reinforcements situated one above the other and on opposite faces of the platform and at which these reinforcements are immobilised relative to the platform during rotation of the latter, a device for cutting said reinforcements from at least one strip of material and for supplying two of the said reinforcements to one of said zones of the platform situated in a portion of the platform lying, in use, outside said thick nesses of the band, means for stepwise driving of the platform during stepwise movements of the band to bring said zones provided with rein forcements in turn to the locality where the reinforcements are applied to the thicknesses of said material, means for immobilising the reinforcements on the said zones of the plat form during their transfer from the said cutting and supplying device up to the locality where they are welded and during the welding oper ation, and means for welding each of the said reinforcements to the corresponding thickness of material.

15. A machine according to claim 14, in which the means for driving the platform is ar ranged to drive the platform always in the same direction one step at a time.

16. A machine according to claim 14 or 15, comprising a folding cone for folding a band of a single thickness of material into said band consisting of two superimposed thicknesses of material.

17. A machine according to any of claims 14 to 16, in which said device for cutting and supplying the reinforcements comprises means for supporting a strip of single thickness material intended to constitute said reinforcements, a knife to divide this strip, substantially into two equal parts, parallel to one of its longitudinal edges, guides arranged to superimpose the two parts of the strip, means for simultaneously driving the two parts of the strip in a stepwise manner, a plate situated downstream of the last-mentioned means for separating the parts of the strip from one another so that, when they are driven, they dispose themselves on opposite faces of said platform, and a knife arranged to move transversely of the longitudinal axes of the parts of said strip, the knife being arranged to separate from said parts of the strip portions of strip supplied to opposite faces of the platform and intended to form the reinforcements, the driving of the parts of the strip in the device and the separation of the said portions of the strip taking place when the platform is at rest and when an empty zone of the platform is opposite the plate of the device.

18. A machine according to any of claims 14 to 17, in which the means for stepwise driving of the platform comprises a jack actuating a mechanism for moving the platform a fixed angular distance corresponding to the angular distance separating two consecutive reinforcement-receiving zones of the platform, the control of the jack being synchronised with the means for moving the band stepwise so that the platform moves during movement of the band of material intended to constitute the bags.

19. A machine according to any of claims 14 to 18 in which the means for immobilising the reinforcements on the said zones of the platform comprise a vacuum pump, a distribution system and pipes connecting the vacuum pump to the said zones which have perforations at which said pipes terminate, these perforations, in both faces of the platform, being covered by the reinforcements so that, when the distribution system applies suction, the reinforcements are fixed to the platform, the distribution system being arranged so that suction is created in a predetermined zone of the platform when the portions of material intended to form a pair of reinforcements have been supplied, to opposite faces of the platform, in the said zone.

20. A machine according to any of claims 14 to 19 in which the means for welding the reinforcements to the two thicknesses of the band material comprise two heating elements situated on opposite sides of the two thicknesses of material and actuable, when the material and the platform are at rest, in opposite directions to grip and weld the thicknesses of material and the reinforcements, the platform, situated between the reinforcements, serving as thermal insulation so that the latter are not welded to each other.

21. A machine for manufacturing bags of heat-weldable plastics material, constructed and arranged substantially as herein described with reference to, and as illustrated in, the accompanying drawing.

22. A bag when made by the method claimed in any of claims 1 to 13 or in the machine claimed in any of claims 14 to 21.