US3552278A

US3552278A - Method and apparatus for making interconnected bags having closure flaps and bottom gussets

Info

Publication number: US3552278A
Application number: US810432*A
Authority: US
Inventors: William Guenther
Original assignee: LION PACKAGING PRODUCTS CO Inc
Current assignee: LION PACKAGING PRODUCTS CO Inc
Priority date: 1967-10-09
Filing date: 1969-01-23
Publication date: 1971-01-05
Anticipated expiration: 1988-01-05

Abstract

Continuous web of heat-sealable material having J-shaped crosssectional shape advanced over a bar having an angular slot. Lip of wider ply of the material guided through slot to fold lip back against outer face of wider ply. As material passes over outer faces of two spaced-apart support plates, an intermediate plate pushes folded edge into region between the support plates to form a gusset. Material then provided with pairs of closely spaced seal lines, and line of perforations between each pair of seal lines.

Description

United States Patent [72] Inventor William Guenther Hicksville, N.Y. [21] Appl. No. 810,432 [22] Filed Jan. 23, 1969 Division'of Ser. No. 673,726,:Oct. 9, 1967,!fatent No. 3,469,769. [45] Patented Jan. 5, 1971 [73] Assignee Lion Packaging Products Company, Inc.

a corporation of New York [54] METHOD AND APPARATUS FOR MAKING INTERCONNECTED BAGS HAVING CLOSURE FLAPS AND BOTTOM GUSSETS 3 Claims, 10 Drawing Figs.

[52] U.S.Cl 93/8, 93/35 [51] lnt.Cl B3lb 1/00 [50] Field ofSearch 93/35, 8

[56] References Cited UNITED STATES PATENTS 3,147,674 9/1964 Hoeppner 93/35 3,194,124 7/1965 Warp Primary Examiner-Bernard Stickney Attorney-Breitenfeld & Levine ABSTRACT: Continuous web of heat-scalable material having .l-shaped cross-sectional shape advanced over a bar having an angular slot. Lip of wider ply of the' material guided through slot to fold lip back against outer face of wider ply. As material passes over outer faces of two spaced-apart support plates, an intermediate plate pushes folded edge into region between the support plates to form a gusset. Material then provided with pairs of closely spaced seal lines, and line of perforations between each pair of seal lines.

PATENTED JAN SIS?! SHEET 1 BF 2 m wt in ATTORNEY5 F a %N\ um. AQ \m\ \w M 7 m m T w\ H A f N u w% l H @mm 7 v Q mN W METHOD AND APPARATUS FOR MAKING INTERCONNECTED BAGS HAVING CLOSURE FLAPS AND BOTTOM GUSSETS This application is a division of copending application, Ser. No. 673,726, filed Oct. 9, 1967, now US. Pat. No. 3,469,769, issued Sept. 30, 1969.

This invention relates to a method and apparatus for making plastic bags of the type formed by two flat rectangular walls joined along three sides and open along the fourth side to define a filling opening.

Flat plastic bags of this type have in recent years gained wide acceptance, and are merchandised primarily for household use. Such bags are shown, for example, in US. Pat. Nos. 3,098,594 and 3,173,601. These bags are usually made, on a mass production basis, from a continuous flattened tube of relatively thin gage plastic material. The tube is provided with transverse heat seal lines spaced apart along its length, each seal line joining the superposed fiat walls of the tube and defining the bottom of one bag. Close and parallel to each seal line the tube walls are perforated or slit to define weakened tear lines. In this condition a length of the flattened tube, representing a quantity of interconnected bags, may be wound on a rigid core and packed in a box. When a bag is needed, the endmost bag is unwound from the core and torn from the next adjacent bag. The bag will be closed along three sides, but open along the fourth side created by the newly torn edge.

Bags of this type serve satisfactorily for many uses, but they do present certain problems. First, they cannot readily be closed. Customarily, short pieces of paper-covered wire are sold with such bags, the wire being twisted around the gathered open end portion of the bag to close it. This procedure is obviously cumbersome. Furthermore, such bags suffer from being two dimensional, i.e., their walls lie in contiguous planes with their edges joined. Hence, the ratio between the holding capacity of these bags and their flat area is relatively small. Solutions to both of these problems are illustrated in US. Pat. Nos. 2,709,467 and 2,842,179, wherein plastic bags are shown having closure flaps and bottom gussets. However, the bags of these patents must be made individually, i.e., they cannot be made in an interconnected series, as described above. Consequently, the convenience of a roll of such bags which can be separated one by one, as needed, is not available.

It is an object of the present invention to provide a method and apparatus for producing a series of interconnected yet readily separable plastic bags having closure flaps and expandable gussets.

To accomplish these objectives, the invention contemplates starting with a continuous length of heat-sealable sheet material longitudinally folded to yield a .I-shaped cross-sectional shape. The material is advanced longitudinally, and during this advancement the lip of the wider ply is guided through an angular slot in a bar over which the material passes, whereby the lip is folded back upon the outer face of the wider ply. Thereafter, as the plies pass over the outer surfaces of two spaced-apart support plates, an intermediate plate pushes the folded edge between the two plies into the region between the plies. In this condition, the material is provided with pairs of closely spaced transverse heat seal lines, the seals serving to fuse together the two plies, to define the opposed side edges of two adjacent bags, the folded back lip, to define a closure flap secured at its ends to the bag sides, and the pushed-in folded edge, to define a bottom gusset for each bag also secured at its ends to the bag sides. Finally, a line of perforations or slits is provided between each pair of seal lines to define a weakened tear line separating adjacent bags.

Additional objects and advantages of the invention will be apparent from the following description in which reference is made to the accompanying drawings.

In the drawings:

FIG. 1 is a face view of an individual bag according to this invention after it has been detached from the remaining bags of its series;

FIGS. 2 and 3 are cross-sectional views taken on lines 2-2 and 3-3, respectively, of FIG. 1;

FIG. 4 is a face view of interconnected bags according to this invention;

FIG. 5 is a cross-sectional view taken on line S-of FIG. 4;

FIG. 6 is a schematic view of a bagmaking apparatus according to this invention; and

FIGS. 7, 8, 9, and 10 are cross-sectional views taken at various points along the length of the bag material as it moves the apparatus of FIG. 6.

At the outset, it should be mentioned that the thickness of the bag material has been exaggerated for the sake of clarity in FIGS. 2, 3, 5, and 7-10. The material employed is preferably thin heat-sealable material such as polyethylene sheeting.

A series of interconnected, but readily separable, bags is shown in FIG. 4, the adjacent bags being separated by transverse lines of slits 16 (see also FIG. 5). The slits 16 constitute lines of weakness between adjacent bags along which the bag material may easily be torn to separate the bags 15. Thus, to obtain an individual bag, as shown in FIG. 1, the bag material is torn along the line of slits 16 between the endmost bag in the series and the next successive bag.

Each bag is formed by two superposed plies or

walls

17 and 18 fused together along their side edges by

heat seal lines

19 and 20. As will be described below, each pair of relatively closely spaced seal lines 19 and 20 (see FIG. 4) is formed simultaneously, but the relatively large distance between each two

successive seal lines

20 and 19 defines the width of an individual bag 15. Each line of slits 16 is located in the relatively small spacing between each pair of

seal lines

19 and 20.

Joined to the upper edge of the bag wall 17, by a fold line 23, is a flap 24. The regions near the end edges of the flap are fused to the

plies

17 and 18 at the

seal lines

19 and 20. The bag is formed, and supplied to the consumer with the flap 24 lying against the outer face of the bag wall 17, as shown in solid lines in FIG. 2. After the bag is filled, through the open mouth defined by the fold edge 23 and the free upper edge 25 of the bag wall 18, the bag may be closed by turning the flap 24 over the bag mouth into the position shown in dot-dash lines in FIG. 2. Manipulation of the flap 24 in this way is permitted, despite the fact that the ends of the flap are secured to the bag walls, by the flexibility of the bag material.

The bottom edges of the

bag walls

17 and 18 are joined by two plies 26 and 27 (FIG. 2) defining a gusset. The plies 26 and 27 are joined along their inner edges by a fold line 28. The plies 26 and 27 are joined by fold lines along their outer edges to the lower edges of the

bag walls

17 and 18, respectively. The regions near the ends of the plies 26 and 27 are fused to the

bag walls

17 and 18 at the seal lines 19 and 20. Thus, the gusset 26, 27 is normally maintained in flattened condition between the

bag walls

17 and 18. However, when the bag is filled, the plies 26 and 27 can swing away from each other to enlarge the volume of the bag.

The manner in which the series of bags 15 shown in FIGS. 1- -5 may be produced is illustrated in FIGS. 6-10. A supply roll 31 of so-called .l-stock is provided. This supply is a web of heat sealable material folded along an offcenter longitudinal line 32 (see FIG. 7) parallel to the edges of the web to form a relatively wide ply 17 and a relatively narrow ply 18, the plies being in superposed relation. Before operation of the apparatus is initiated, the J-shaped web is threaded through the machine. The web is drawn around guide rollers 34 and a slotted bar 35, the latter being supported at its ends by a bracket 36 secured to the machine frame (not shown). The lip 24 of the wider ply 17, which extends beyond the free edge 25 of the narrower ply 18, is turned back toward the outer face of the ply 17 and slipped into a slot 37 (see FIG. 8) in the bar 35. The slot 37 is arranged at an acute angle to the plane of the web so that the slotted bar serves to continuously fold the lip 24 back toward the outer face of the ply 17 as the web is continuously advanced.

After leaving the bar 35, the web travels to a roller 40 in the region of which the folding of the lip 24 against the ply 17 is completed (FIG. 9), so that the ply 24 now constitutes a flap. From the roller 40, the

plies

17 and 18 are guided around the outer faces of two parallel, spaced-apart, rigid support plates 41 (see FIG. A third intermediate plate 42 extends part way into the space between the plates 41. The region of the web adjacent to the fold line 32 (FIG. 7) is threaded between the margins of the

plates

41 and 42 in a sinuous fashion to form the gusset plies 26 and 27 and the fold line 28, the latter being the fold line 32 reversed.

After leaving the

plates

41 and 42,'the web travels to a roller 43, at which the gusset plies 26 and 27 and the

bag wheels walls

17 and 18 are flattened against each other, and then to a heat sealing station comprising a heat sealing device 44 and a platen roller 45. The heat sealer 44 reciprocates, as indicated by the double-headed arrow, toward and away from the platen roller 45, and is provided with two parallel, spaced apart sealing

edges

46 and 47. Thus, each time the heat sealer 44 strikes the platen roller 45, with the bag material between them, a pair of relatively close seal lines '19 and are formed by the sealing edges 46 and 47, respectively. The reciprocation rate of the heat sealer 44 is related to the speed of advancement of the web so that lengths of the web equal to the desired width of the bags pass between the heat sealer and platen roller during the intervals between successive engagements of the heat sealer and platen roller. Any appropriate tensioning means (not shown) for the web to permit instantaneous halting of the web at the heat sealing station without interfering with the continuous web advancement maybe employed.

From the sealing station, the web moves around a guide roller 50 to a cutting station comprising a rotating knife 51 and a stationary platen 52. The cutting edge of the knife is serrated, so that only short unconnected regions of the cutting edge contact the platen 52. The knife rotates in the direction indicated by the arrow at a speed related to the speed of advancement of the web. in this way, the knife 51 is caused to contact the platen 52 with the web between them only when the relatively narrow region of the web between the seal lines 19 and 20 is between them. The serrated edge of the knife thereby produces a line of slits 16 serving as the tear lines between adjacent bags.

The completed series of interconnected bags is then wound on a takeup roll 53 with the aid of a pressure roll 54. Rotation of thetakeup roll 53,'by means not shown, serves to advance the web in a longitudinal direction through the apparatus. After operation of the apparatus has been terminated, either because of depletion of the supply roll 31 or for some other reason, the bags on the takeup roll 53may bejrewound or rigid cores (not shown) in suitable bearing bags packed in boxes.

The invention has been shown and described quantities, and the c0resuch limitations are included in the appended claims.

I claim:

1. A method of making a series of interconnected separable bags comprising the steps of providing a continuous web of heat sealable sheet material folded along an offcenter longitudinal line to define two superposed plies one of which' is beyond the free edge of the narrower to said offcenter fold line into the region between said plies to form a four ply portion along the other longitudinal edge "off the web, intermittently heat sealing together all of said web plies along pair of spaced-apart transverse lines, and partially severing all of said plies along a line located between each pair of seal lines.

2. A method as defined in claim 1 including the final stepof roging'up said interconnected bags on to a core.

pparatus for producing a series of interconnected bu separable bags comprising means for longitudinally advancing a continuous web of heat sealable sheet material folded along an offcenter longitudinal line to define two superposed plies one of which is widertha'n ,theother, the wider ply having a-lip extending beyond the free edge of the narrower ply, a bar over which said webis drawn with the wider ply contacting'the bar,

said bar having a slot arranged at an acute angle to, the web as it moves over the bar, said slot accommodatingthe lip of the web and serving to turn it back toward the outer face of the wider web ply to form a flap, a pair of spaced-apart support plates, each ply sliding over the outer face of one of said plates, an intermediate plate between said support plates for pushing a central'region of the web into the space between the support plates to form a gusset, a heat sealer for intermittently applying to themoving web two spaced-apart seal lines transverse to the direction of web advancement, and a knife for partially severing the web between-each pair of seal lines.

in preferredw form only, and by way of example, and may variations may made in the invention which will still be comprised withinjtjs Y spirit. It is understood, therefore, that, the invention is ntjt. limited many specific form or-embodiment except insofar as.

Claims

1. A method of making a series of interconnected but separable bags comprising the steps of providing a continuous web of heat sealable sheet material folded along an offcenter longitudinal line to define two superposed plies one of which is wider then the other, the wider ply having a lip extending beyond the free edge of the narrower ply, advancing the web longitudinally, continuously folding said lip away from said narrower ply and against the outer face of said wider ply to form a three ply region along one longitudinal edge of the web, continuously introducing longitudinal portions adjacent to said offcenter fold line into the region between said plies to form a four ply portion along the other longitudinal edge of the web, intermittently heat sealing together all of said web plies along pair of spaced-apart transverse lines, and partially severing all of said plies along a line located between each pair of seal lines.

2. A method as defined in claim 1 including the final step of rolling up said interconnected bags on to a core.

3. Apparatus for producing a series of interconnected but separable bags comprising means for longitudinally advancing a continuous web of heat sealable sheet material folded along an offcenter longitudinal line to define two superposed plies one of which is wider than the other, the wider ply having a lip extending beyond the free edge of the narrower ply, a bar over which said web is drawn with the wider ply contacting the bar, said bar having a slot arranged at an acute angle to the web as it moves over the bar, said slot accommodating the lip of the web and serving to turn it back toward the outer face of the wider web ply to form a flap, a pair of spaced-apart support plates, each ply sliding over the outer face of one of said plates, an intermediate plate between said support plates for pushing a central region of the web into the space between the support plates to form a gusset, a heat sealer for intermittently applying to the moving web two spaced-apart seal lines transverse to the direction of web advancement, and a knife for partially severing the web between each pair of seal lines.