US2820497A

US2820497A - Art of forming bag bottoms

Info

Publication number: US2820497A
Application number: US580050A
Authority: US
Inventors: Kenneth A Rusch
Original assignee: Milprint Inc
Current assignee: Milprint Inc
Priority date: 1956-04-23
Filing date: 1956-04-23
Publication date: 1958-01-21
Anticipated expiration: 1975-01-21

Description

Jan. 21, 1958 K. A. RUSCH 2,820,497

ART oF FORMING BAG BoTToMs Filed April 25, 195e ,4 frog/Vans.

it l? ART F FRMHNG BAG BOTTOMS Kenneth A. Rusch, Milwaukee, Wis., assigner to Milprint, inc., lviiiwauiree, Wis., a corporation of Delaware The present invention relates generally to improvements in the art of packaging, and relates more particularly to the provision `of an improved commodity bag and' the method of producing the same.

A primary object of the invention is to providey an` improved commodity receiving bag which is strong and durable in construction and has an exceedingly strong and effective leak-proof bottom seal and which may moreover `be readily produced in quantity and at low cost in accordance with a novel method.

It has heretofore been co-mmon practice to commercially produce commodity bags from webs of heat scalable ribbon/stock by first folding the advancing web into fiat tubular formation, then longitudinally heat sealing overlapped edge portions to complete the* tube, thereafter severing the tube into sections of desired l`ength and by subsequently either sealing the Walls directly to each other transversely across an end of the successive sections by application of heat and pressure or by folding an end ofl each section back upon itself and finally applying heat and pressure tothe four thicknesses of the folded over portion to thereby heat seal the. endv of each tube section and provide the bag. While these, prior heat 'sealing methods and the bags produced thereby have proven quite satisfactory as applied to packaging materials o'f certain types capable of being readily heat sealed While withstanding relatively high temperatures for sufficient periods of time to permit firm bonding and strong seals, many films which possess highly desirable characteristics for packaging purposes have an extremely critical range in which heat may be applied safely and Without resultant damage 'to the material, and these films therefore cannot all be readily adapted for use as commodity bags in accordance with prior production methods of heat sealing.

It is therefore a more specific object of the present invention to provide an improved commodity bag structure and method of producing the same which obvia-te the objections and disadvantages attendant prior known structuresand production methods.

Another specific object of this invention isl to provide :t commodity bag formed of heat sealable material and. having a novel and improved highly efficient leak-proof and sift-proof bottom seal formed with the aid of heat andpressure.

Another specic object of my invention is to provide an improved method of commercially producing commodity bags and of effecting the bottom or transverse end seals therein by a relatively simple and unique heat sealing operation.

Still another specific object of my present invention is to provide an improved commodity bag comprising, a` flat tubular body, one end of the body being folded back upon one of the side walls thereof and being secured to the adjacent side wall by a heat seal extending transversely thereacross, and the folded end portion beyond theheatseal being free of attachment to the adjacent side wall with both thicknesses of they free portion thereof being secured to each other.

2,82@,497 Patented Jan. 2l, 1958 An additional specific object of the present invention is to provide an improved method of producing commodity bags, which comprises, forming a fiat tubular body from asheet of heat scalable material, transversely folding an end of the body back upon one of its side walls, sealing the folded portion adjacent the fold line through both thicknesses thereof to the adjacent body side wall by application of heat and pressure, and securing both thicknesses of the free end of the folded portion beyond the seal to each other by application of heat and pressure only to the folded portion.

These and other specific objects and advantages of the invention will become apparent from the following detailed description.

A clear conception of the features constituting the present invention and of the several steps of the improved method of producing a typical commodity bag in accordance therewith may be had by referring to the draw ing accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig; l is a fragmentary side view diagrammatically illustrating typical apparatus for facilitating production of commodity bags in accordance with the improved method and showing a flat tube of suitable packaging material being transversely severed;

Fig. 2 is another fragmentary diagrammatic side view just prior to the transverse folding operation;

Fig. 3 is a similar fragmentary diagrammatic side View showing the start of the folding operation;

Fig. 4 is still another fragmentary side view showing the end of the tube folded back over the upper guide plate;

Fig. 5 is a fragmentary diagrammatic side view just prior to the heat sealing operation;

Fig. 6 is a similar view with the folding plate withdrawn and showing the tube being transversely heat sealed to form the bag bottom;

Fig. 7 is an enlarged fragmentary perspective view illustrating the same step as shown in Fig. 5 in which the end of the tube is folded and is about to be transversely sealed; and

Fig. 8 is a similarly enlarged perspective view of a typical flat commodity bag produced in accordance with thc improved method and embodying the improved bottom construction.

While the invention has been particularly shown and described herein as being especially advantageously applicable in the production of plain square cut commodity bags formed of thin heat scalable films which are highly sensitive to heat and require great care in the control of the heat during sealing operations, it is not desired or intended to thereby unnecessarily restrict or limit the invention since the improvements may also be utilized to good advantage in the production of gusset type bags formed of any heat scalable materials. It is furthermore contemplated that certain specific descriptive terms used herein shall be given the broadest possible interpretation consistent with the disclosure.

In accordance with my present improved method of producing commodity bags having the novel and improved bottom construction, I initially fold a continuous ribbon or web of thin iiexible heat scalable film material along spaced longitudinal lines and seal the overlapping longitudinal edges thereof in a customary manner to form a flat tubular body which may be severed into desired lengths. Next, an end portion of the tubular body is folded back upon one of its side walls along a transverse fold line, and the body side walls are internally separated adjacent to the fold line while the folded portion remote from the fold line is separated from the adjacent body side wall. Then, sealing heat and pressure isl applied transversely across the folded portion adjacent to the fold line and in the area in which the side walls are internally separated to thereby secure both thicknesses of the folded portion to each other and to the adjacent side Wall only, and sealing heat and pressure is likewise applied transversely across the folded portion remote from the fold line and in the area in which the folded portion is separated from the adjacent side wall to thereby secure both thickneses of the free end of the folded portion only to each ot er.

In the commercial exploitation of the improved bag producing method, the at tubular body 10 and longitudinal side seam 11 thereof may be formed with the aid of commercially available apparatus and in a well known manner requiring no further description, and the tube may be transversely severed into desired lengths with the aid of suitable cooperating

knives

12, 13 as shown in Fig. 1. To maintain the side Walls 1d, 15 of the tubular body 10 internally separated, the tube is advanced about a separating and backing plate or internal former 16 and directly beneath an external separating and backing plate 17 which also serves as a guide plate during the transverse folding operation, the plate 17 being reciprocable from a position shown in Figs. 2 to 4 inclusive wherein the forward edge thereof is in approximate alineinent with the forward edge of the former 16 to a position such as shown in Figs. 5 and 6 in which the plate 17 is retracted to a position somewhat rearwardly of the forward edge of the former 16. For folding the end portion 18 of the tube 15B back upon the side wall 14, a suitable folding plate 19 may be provided which is vertically and laterally movable, as shown in Figs. 2 to 5, to fold the portion 18 about the edges of the cooperating

plates

16, 17 to a position above the side wall 14, whereupon the folding plate 19 may be withdrawn and the plate 17 may be retracted as described to a position between the folded portion 18 remote from the fold line 2t? and the side wall 14 of the tube. The final sealing operation may then be performed with the aid of a heat sealing bar 21 having laterally spaced legs 22, Z3 extending transversely across the tube, the bar 21 being vertically movable into contact with the folded portion 18 of the tube, as shown in Figs. 5 and 6, with the leg 22, thereof cooperating with a backing pad 24 on the internal separating plate 16 to apply sealing heat and pressure transversely across the portion 1d adjacent to the fold line 2li and the leg 23 thereof cooperating with a backing pad 25 on the separating plate 17 to apply sealing heat and pressure transversely across the portion 1S remote from the fold line 2li.

The commodity bag thus formed comprises, in general, a flat tubular body 1t) having an end portion 18 thereof folded back upon the side wall alongv a transverse fold line 2l), the folded end portion 1u being secured through both thicknesses thereof only to the adjacent side wall 14 of the body adjacent to the fold line 2d as by the heat seal 26 extending transversely across the body, and the folded end portion 13 remote from the fold line 2G beyond the heat seal 26 being free of attachment to the adjacent side wall 14 and having both thicknesses of the free portion secured only to each other by a separate transverse heat seal 27.

rom the foregoing detailed description, it is believed apparent that the present invention contemplates the provision of a bag-like receptacle having an improved strong, durable and leak-proof bottom structure adapted to be produced in accordance with a novel and improved production method. The bags produced by the method possess full capacity and the bottom is effectively sealed transversely thereacross by means of the heat seal 26 which firmly unites both thicknesses of the folded bottom portion 1fand one adjacent side wail 141 to thereby give full capacity to the bag, and the additional heat seal 27 firmly unites the free end of the portion 18 through both thicknesses of the material entirely independent of both of the bag walls to thereby give added assurance as to the leak-proof and sift-proof qualities of the bag. By means of the improved method, the heat and pressure required to form the bottom seal is considerably reduced because of the fact that a minimum number of thicknesses of material are operated upon thus obviously reducing the amount of heat required to effectively seal the desired areas. Furthermore, the improved method may be carried out in a continuous manner and is readily adapted for commercial production of the improved bag units. The method enables quantity production of bags from all types of heat scalable materials even though certain of these materials may have a very critical range within which heat may be safely applied, and it is likewise effective in the production of commodity bags from materials which are not necessarily extremely critical or sensitive to high sealing heats.

It should be understood that it is not desired or intended to limit this invention to the exact steps of the production method or to the precise details of construction of the bags herein shown and described, since various modifications within the scope of the appended claims may occur to persons skilled in the art to which this invention pertains.

I claim:

1. The method of producing commodity bags, which comprises, forming a flat tubular body from a sheet of heat scalable material, transversely folding an end of the body back upon one of its side walls, sealing the folded portion adjacent to the fold line through both thicknesses thereof to the adjacent body side wall by application of heat and pressure, and securing both thicknesses of the free end of the folded portion beyond the seal to each other by application of heat and pressure only to the free end of the folded portion.

2, The method of producing commodity bags, which comprises, initially forming a flat tubular body from a sheet of heat scalable material, transversely folding an end of the body back upon one of its side walls, sealing the folded portion adjacent to the fold line through both thicknesses thereof to the adjacent body side wall by application of heat and pressure, and securing both thicknesses of the free end of the folded portion beyond the seal to each other by application of heat and pressure to the free end of the folded portion while providing means for preventing the applied heat from being transmitted to the adjacent body side wall.

3. The method of producing commodity bags, which comprises, initially forming a dat tubular body from a sheet of heat scalable material, transversely folding an end of the body back upon one of its side walls, sealing the folded portion adjacent to the fold line through both thicknesses thereof to the adjacent body side wall by application of heat and pressure, while providing means for preventing the applied heat from being transmitted to the other body side wall, and securing both thicknesses of the free end of the folded portion beyond the seal to each other by application of heat and pressure to the free end of the folded portion while providing means for preventing the applied heat from being transmitted to the adjacent body side wall.

4. The method of producing commodity bags, which comprises, initially forming a flat tubular body from a sheet of heat scalable material, transversely folding an end of the body back upon one of its side walls, internally separating the body side walls adjacent to the folded end, applying heat and pressure to the folded portion adjacent to the fold line through both thicknesses of the folded portion and the adjacent body side wall to thereby secure both thicknesses of the folded portion to each other and to the adjacent side wall only, separating the free end of the folded portion beyond the seal from the adjacent body side wall, and applying heat and pressure to the free end of the folded portion to thereby secure both thicknesses thereof only to each other.

5. The method of producing commodity bags, which comprises, initially forming a llat tubular body from a sheet of heat scalable material, folding an end portion of the body back upon one of its side walls along a transverse fold line, internally separating the body side walls adjacent to the fold line while separating the folded portion remote from the fold line from the adjacent body side Wall, applying heat and pressure to the folded portion adjacent to the fold line to thereby secure both thicknesses of the folded portion to each other and to the adjacent side Wall only while also applying heat and pressure to the folded portion remote from the fold line to thereby secure both thicknesses thereof only to each other.

6. A commodity bag comprising, a at tubular body having an end portion thereof folded back upon itself to close the end of the body, said folded end closure portion being secured to the adjacent side wall of saidy body by a heat seal extending transversely thereacross, and said folded end closure portion beyond said heat seal being free of attachment to the adjacent side wall with both thicknesses of said free portion being secured to each other, the opposed side walls of said body being free of attachment.

7. A commodity bag comprising, a flat tubular body having an end portion thereof folded back upon itself, said folded end portion being secured only to the adjacent side wall of said body by a heat seal extending transversely thereacross, and said folded end portion beyond said heat seal being free of attachment to the adjacent side wall with both thicknesses of said free portion being secured only to each other.

8. A commodity bag comprising, a fiat tubular body having an end portion thereof folded back upon itself along a transverse fold line, said folded end portion adjacent to said fold line being secured only to the adjacent side wall of said body by a heat seal extending transversely thereacross, and said folded end portion remote from said fold line and beyond said heat seal being free of attachment to the adjacent side wall with both thicknesses of said free portion being secured only to each other.

9. A commodity bag comprising, a flat tubular body having an end portion thereof folded back upon itself along a transverse fold line, said folded end portion adjacent to said fold line being secured through both thicknesses thereof only to the adjacent side wall of said body by a heat seal extending transversely thereacross, and said folded end portion remote from said fold line and beyond said heat seal being free of attachment to the adjacent side wall with both thicknesses of said free portion being secured only to each other by a separate heat seal.

References Cited in the le of this patent UNITED STATES PATENTS