US3023679A

US3023679A - Three dimensional bag and method and apparatus for making same

Info

Publication number: US3023679A
Application number: US679455A
Authority: US
Inventors: Thomas E Piazze
Original assignee: Continental Can Co Inc
Current assignee: Continental Can Co Inc
Priority date: 1957-08-21
Filing date: 1957-08-21
Publication date: 1962-03-06
Anticipated expiration: 1979-03-06

Description

March 6, 1962 T. E. PIAZZE THREE DIMENSIONAL BAG AND METHOD AND APPARATUS FOR MAKING SAME 3 Sheets-Sheet 1 Filed Aug. 21, 1957 INVENTOR T/zomas EP/ azze BY Wfim, f zz/M44; fig;

March 6, 1962 T. E. PIAZZE THREE DIMENSIONAL BAG AND METHOD AND APPARATUS FOR MAKING SAME 3 Sheets-Sheet 2 Filed Aug. 21, 1957 ORNEYS INVENTOR r/zom as E Biazze fnzz, AMW J BY WW,

March 6, 1962 T. E PIAZZE THREE DIMENSIONAL BAG AND METHOD AND APPARATUS FOR MAKING SAME 5 Sheets-Sheet 3 INYENTOR ATTORNEYS United States Patent w 3,023 679 THREE DllVIENSIONAL BAG AND METHOD AND APPARATUS FOR MAKING SAME Thomas E. Piazza, Mount Vernon, Ohio, assignor to Contlnental Can Company, Inc, New York, N.Y., a corporation of New York Filed Aug. 21, 1957, Ser. No. 679,455 11 Claims. (Cl. 93-8) This invention relates to novel flexible bags and to a novel apparatus and method for fabricating such bags from thin heat-scalable plastic material, for example cellophane or Pliofilm.

One object of the invention is to provide a novel unit normally in flat form but readily expansible into the form of a bag having substantially rectangular side and edge walls and a substantially rectangular bottom, and having uniquely related seams formed by heat-sealing edges of the thermo-plastic material together.

The flat unit includes two opposed side walls, each of said side walls having two side edges disposed in parallel relation from the upper edge of the wall to points near the lower edge thereof. The lower end portions of these side edges, however, converge downwardly from said points to said lower edge. An upwardly projecting accordion pleat is disposed between the lower end portions of the two side Walls and has the lower edges of its two walls integrally joined to the lower edges of said side walls. The central fold line of the accordion pleat has its ends disposed at the aforesaid points. The end edges of the accordion pleat converge downwardly and are heatsealed to the downwardly converging lower ends of the side edges of the two side walls, and the vertical major portions of said side edges are heat-sealed together from the aforesaid ends of the central fold line of the pleat to the upper end of the unit.

When the above described flat unit is expanded into bag form, the two side Walls of said unit form two side walls and two edge walls for the bag, the accordion pleat opens and forms the bag bottom, and the end portions of this pleat form triangular gussets integral with said bottom and heat sealed to said edge walls of the bag.

The invention aims to provide a simple, practicable and rapid method for successfully shaping, cutting and heat-sealing the units in large quantities, with no danger of the sides of the accordion pleats becoming fused together.

A substantially flat tube of the desired flexible plastic is formed and the longitudinal edge portions of this fiat tube are inwardly deformed to provide each of said edge portions with an inwardly projecting longitudinally extending accordion pleat. The flat tube is then longitudinally cut into two longitudinal halves each having one of the accordion pleats. These halves are then transversely cut into separate bag forming units and the thus formed edges of each unit are heat-sealed together simultaneously with the transverse cutting operations. During performance of these cutting and sealing operations, the walls of the accordion pleat are prevented from becoming fused together by means of anti-blocking coating applied to the portions of the plastic which form said pleat walls. For these coatings, straight shellac diluted in alcohol and acetone may well be used. After they are applied and the solvents dissipated, the shellac which is non-compatible to the plastic, prevents welding together of the walls of the accordion pleats.

The invention further aims to provide for forming the above mentioned flat tube either by flattening a cylindrical plastic tube or by folding a plastic Web, the nonblocking coatings in either case being applied to the plastic in the form of stripes.

A still further aim of the invention is to provide a ice 2. novel apparatus for use in performing the required method steps.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a diagrammatic side elevation, partly in section, showing one form of the apparatus.

FIGURES 2, 3 and 4 are detail horizontal sectional views on lines 2-2, 3-3 and 4-4 of FIGURE 1.

FIGURE 5 is an enlarged diagrammatic top plan view, partly broken away and in section, of the apparatus shown in FIGURE 1.

FIGURE 6 is a further enlarged transverse sectional view on line 6-6 of FIGURE 1.

FIGURE 7 -is a view similar to FIGURE 1 but showing another form of apparatus.

FIGURE 8 is a fragmentary elevation as indicated by the arrow 8 of FIGURE 7.

FIGURE 9 is an enlarged transverse sectional view on line 9-9 of FIGURE 7.

FIGURE 10 is a perspective view of the lower end portion of one of the flat bag-forming units.

FIGURE 11 is a perspective view of the lower end portion of one of the fully opened bags.

FIGURES l2 and 13 are vertical sectional views'on lines 1212 and 1313 of FIGURES 10 and 11, respectively.

In the apparatus shown in FIGURES l, 5 and 6, two continuously driven pull rolls 1 and 2 are provided for pulling a cylindrical plastic tube 3 downwardly from an extrusion die and gradually converting said cylindrical tube into a flat tube 4. Creasing plates or disks 5 are provided above the pull rolls 1 and 2 for inwardly deforming the longitudinal edge portions of the Hat tube 4 to provide said edge portions with inwardly projecting, longitudinally extending accordion pleats 6. Before these pleats 6 are formed, the portions of the tube 3 from which they are to be formed, are coated with stripes 7 of non-blocking material, by means of spray nozzles 8. This non-blocking material is preferably straight shellac diluted in alcohol and acetone. The solvent, however, is evaporated from the stripes 7 by a suitable dryer 9 and these stripes are then non-compatible to the plastic. Consequently, the walls 10 of the accordion pleats 6 are prevented from becoming fused together when heat-sealing of cut edges of the plastic is later effected.

A belt support 11 is horizontally spaced from the pull rolls 1 and 2, and the upper reach of a belt 12 passes over said support 11 to horizontally support the fiat tube 4. A feed roll 13 coacts with'the receiving end of the belt 12 and both said feed roll and belt are intermittently driven to advance the flat tube 4, step by step.

Between the roll 2 and the roll 13, a slitting knife 14 and coacting roller 15 are provided to longitudinally cut the flat tube 4 into two longitudinal halves 16, each of which has one of the accordion pleats 6.

Over the'belt 12 a suitably heated cutting means 17 is provided to transversely cut the advanced flat tube halves 16 into separate bag forming units 18 and to heat-seal the thus-formed edges of the plastic together. The cutting means 17 is vertically reciprocated and descends after each advance step imparted to the tube halves 16. During such cutter operation, a loop 19 (FIGURE 1) forms in the flat tube 4 due to the constantly driven feed rolls 1 and 2. This loop supplies the required tube length for the next step imparted to the tube by the feed roll 13 and belt 12.

A take-away roll 20 pulls each unit 18 away from the 3 cutting means 17 and a discharge roll 21 delivers the successively completed units to a receiver 22.

The cutting means 17 includes an elongated straight knife 23 which cuts the tube halves 16 from the inner fold line 24 of one of said halves to the corresponding fold line of the other of said halves. The cutting means 17 also includes two diverging knives 25 at each end of the knife 23, for cutting the pleated edge portions of the two halves 16.

The triangular scraps of plastic cut from the pleated edge portions of the flat tube halves 18 are lifted by intermittently actuated suction arms 26 and delivered to suction conduits 27 which convey them away as waste.

As shown in FIGURES and 12, each flat unit 18 includes two opposed side walls 28. Each of these side walls has two side edges 29 disposed in parallel relation from its upper edge to points 30 near its lower edge 31. The lower end portions 32 of the side wall edges 29 converge downwardly from the points 30 to the lower edge 31. The accordion pleat 6 is disposed between the lower end portions of the two side walls 28, and the ends of the inner fold line 24 of said pleat are located at the points 30. The lower edges of the pleat walls 10 are integral with the lower edges 31 of the side walls 28, and the end edges 33 converge downwardly and extend along the above described edges 32. The end edges 33 of one of the pleat walls 10 are heat-sealed to the edges 32 of one of the side walls 28: and the corresponding end edges of the other of said pleat walls 10 are heat-sealed to the edges 32 of the other of said side walls 28. The side edges 29 of the two side walls 28 are heat sealed together. All of the heat-sealing of the various edges was effected by the heated cutting means 17 as it formed said edges.

When the unit of FIGURES 10 and 12 is opened to the fully expanded condition of FIGURES 11 and 13, the bag thus produced has two spaced rectangular side walls 34, two edge walls 35, a rectangular bottom 36 and two triangular gussets 37. Each edge wall 35 has two vertically elongated sections 38 integral with the side walls 34, said sections 38 having vertical inner edges 39 which are heat-sealed together from their upper ends to a point 40 near the lower end of the bag. The two sections 38 have lower end edges 41 which diverge downwardly from the point 40 to the lower edges 42 of the side walls 34. The longitudinal edges of the bottom 36 are integral with the lower edges 42 of the side walls 34: and the triangular gussets 37 are integral with the ends of said bottom. These gussets extend upwardly from the bottom 36 in the planes of the edge walls 35 and have upwardly converging edges 43 which are heat-sealed to the end edges 41 of the edge wall sections 38.

In FIGURE 7, an apparatus is shown for forming a flat tube 4a from a flat web 3a. The

elements

5a, 1a, 2a, 14a, a, 12a, 13a, 11a, 17a and 26a are identical with the corresponding elements of FIGURE 1 and perform the same functions. Various guide rolls 44 are provided for the Web 3a and means 45 is provided for applying stripes 7a of non-blocking material to said web before it is folded to form the tube 4a. The longitudinal center of each stripe 7a is spaced inwardly from the related longitudinal edge of the web 3a a distance equal to about one fourth of the width of said web. Suitable conventional means 46 are employed to inwardly fold the longitudinal edge portions 47 of the Web 3a to form the flat tube 4a. As the upper wall of this tube has the equivalent 48 of a longitudinal slit, the knife 14a cuts only through the lower wall of the tube.

Either form of apparatus performs the steps of forming a flat flexible thermo-plastic tube and inwardly deforming the longitudinal edge portions thereof to provide each of said edge portions with an inwardly projecting longitudinally extending accordion pleat, longitudinally cutting said flat tube into two longitudinal halves each having one of said accordion pleats, transversely cutting said halves into separate bag-forming units and heat-sealing together the thus-formed edges of each separate unit, and preventing heat-sealing of the side walls of said accordion pleats together during performance of the transverse cutting operations. Also, with either form of apparatus, each transverse cutting operation is performed on a straight line from one of the accordion pleats to the other and is performed on an oblique line across each of said pleats, each oblique cut being at an obtuse angle to the contiguous straight cut.

It will be seen from the foregoing that a novel and advantageous method, a novel and advantageous apparatus, a novel and advantageous flat unit expansible into bag form, and a novel and advantageous three-dimensional bag, have been disclosed. However, attention is invited to the possibility of making variations, within the scope of the invention.

I claim:

1. In a method of manufacturing plastic bags, the steps of forming a flat flexible thermo-plastic tube and inwardly deforming the longitudinal edge portions thereof to provide each of said edge portions with an inwardly projecting longitudinally extending accordion pleat, longitudinally cutting said flat tube in two longitudinal halves each having one of said accordion pleats, transversely cutting said halves into separate bag-forming units and heat-sealing together the thus-formed edges of each separate unit, and preventing heat-sealing of the side walls of said accordion pleats together during performance of the heatsealing operations by the application of coatings which are not heat-scalable to the areas of the plastic which form the contiguous faces of said pleat side walls.

2. The method defined in claim 1 in which the operation of forming said fiat tube comprises flattening a preformed cylindrical tube.

3. The method defined in claim 1, in which the operation of forming said flat tube comprises inward folding of longitudinal edge portions of a fiat web onto the interventing portion of said web.

4. An apparatus for forming plastic bags from a substantial-ly cylindrical thermoplastic tube, comprising means for externally applying two longitudinal stripes of non-blocking material to diametrically opposite portions of the cylindrical tube, means for deforming the striped cylindrical tube into the form of a flat tube having two inwardly projecting longitudinally extending accordion pleats at its edges, said pleats being formed by the striped portions of the tube, means for longitudinally cutting the fiat pleated tube into two longitudinal halves each having one of said pleates, and heated cutting means for transversely outing said halves into bag-forming units and simultaneously heat-sealing the cut edges of said units together.

5. A structure as specified in claim 4, in which said heated cutting means comprises a straight knife for outting through the flat tube halves from one of said pleats to the other, and diverging knives at the ends of said straight knife for cutting through the pleated edge portions of said tube halves.

6. An apparatus for forming plastic bags from a thermoplastic web, comprising means for applying two longitudinal stripes of non-blocking material to one side of the web, the center line of each stripe being spaced from one edge of the Web a distance which is about one fourth of the web width, means for inwardly folding the longitudinal edge portions of the web to form a flat tube and for inwardly deforming the longitudinal edge portions of said tube to provide two inwardly projecting longitudinally extending accordion pleats, said pleats having said stripes on the inner faces of their opposed sides, means for longitudinally cutting the flat pleated tube into two longitudinal halves each having one of said pleats, and heated cutting means for transversely cutting said halves into bag-forming units and simultaneously heatsealing the cut edges of said units together.

7. A structure as specified in claim 6, in which said heated cutting means comprises a straight knife for cutting throught the fiat tube halves from one of said pleats to the other, and diverging knives at the ends of said straight knife for cutting through the pleated edge portions of said tube halves.

8. In a method of manufacturing plastic bags, the steps of forming a flat thermo-plastic tube and inwardly deforming longitudinal edge portions thereof to provide each of said edge portions with an inwardly projecting longitudinally extending accordion pleat, longitudinally cutting said pleated fiat tube into longitudinal halves each having one of said accordion pleats, and in a single operation transversely cutting said pleated tube halves into separate bag-forming units and heat-sealing together edges of each separate bag-forming unit while preventing heatsealing of side walls of said accordion pleats together during the performance of the heat-sealing operations, said side Walls of said accordion pleats being prevented from becoming heat-sealed together by the application of coatings which are not heat-scalable to the areas of the plastic which form the contiguous faces of said pleat side walls.

9. In a method of manufacturing plastic bags, the steps of forming a flat thermo-plastic tube and inwardly deforming longitudinal edge portions thereof to provide each of said edge portions with an inwardly projecting longitudinally extending accordion pleat, applying and adhering to the areas of the tube which form the contiguous faces of the pleat side walls a means for preventing the heat-sealing together of the opposing faces of the pleat side walls, longitudinally cutting said pleated fiat tube into longitudinal halves each having one of said accordion pleats, and in a single operation transversely cutting said pleated tube halves into separate bag-forming units and heat-sealing together edges of each separate bag-forming unit while the means prevents heat-sealing of side walls of said accordion pleats together during the performance of the heat-sealing operations.

10. The method of claim 9 wherein the heat-sealing preventing means is applied to the tube prior to the formation of the accordion pleats.

11. The method of claim 9 wherein the heat-sealing preventing means is applied to the tube prior to the formation of the accordion pleats and is permanently adhered to the tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,185,647 Penn et al. Jan. 2, 1940 2,615,375 Rowe et al. Oct. 28, 1952 2,631,332 Reber Mar. 17, 1953 2,690,199 Bennorth Sept. 28, 1954 2,707,985 Binnall May 10, 1955 2,788,039 Schjeldahl Apr. 9, 1957 2,800,163 Rusch July 23, 1957 2,815,063 La Fleur Dec. 3, 1957 FOREIGN PATENTS 1,044,871 France June 24, 1953