Field Of Invention

The present invention relates to an apparatus and a method for producing a bag with an integrally closing bottom and self-closing top and a bag so produced. The present invention more specifically relates to an apparatus and a method for producing a bag with an integrally closing bottom and a top either open or self-closing, a bag so produced.

Background Of Invention

Bags or sacks have been in use for packing/storage/transportation of materials such as food grains, flour, and industrial materials of all kinds.

The bags are generally made from the either tubular web material which is obtained from the circular weaving machine or flat machine which can be made in two steps, firstly obtaining flat fabric from the weaving machine and then secondly making tube out of it in tuber machine,

Bags which are made from the tubular fabric are generally but not specifically used for storing pulverised materials such as cement, chemicals etc. These bags are economical as tubular fabric is directly weaved on the weaving machine. However, these bags differ in the width due to the width variation fabric obtained from the weaving machine, so during material filling and stacking individual bag differs slightly.

On the other hand, the bags which are made from the flat fabric formed into tube in the tuber machine are more premium looking bags which are used for storing shopping commodities as these looks attractive when coated with a layer of colourful biaxially oriented polypropylene (BOPP). However, these bags are not as good in strength when compared to the bag obtained from the tubular fabric, due to the joining crease formation during making of tube from the flat fabric.

There are primarily two types of bags used widely in the industry : pillow type and box type.

Box type bags are made using hot sealing technique, however, their manufacturing processes are capital intensive involving complex mechanisms in formation of bag. On the other hand, pillow type bags are made mainly by stitching one end of the tubular web by suitable folding of the end to be stitched. Stitching is a simple and economic process which can either be carried out manually or automatically. However, it compromises the integrity and strength of the web due to puncturing of the web material by the needle.

Some manufacturers use high strength material to compensate for the loss of strength due to holes made by needles used for stitching, however, it is not possible to achieve complete sealing of the filled materials from external environment. Stitching also results in pilferage and spillage of material, especially during transport and handling of the bags. Bottom stitched bags are also problematic for packaging of hygroscopic material as it can absorb moisture from atmosphere from the holes made by the needle. The folding that is necessary at the end to be stitched also requires webs of greater lengths, which is an economic disadvantage.

To overcome the problems of loss of integrity of seals and pilferage etc., pillow shaped bags may be sealed using thermal sealing techniques such as heat bar or ultrasonic methods, however, these methods require precise operational control and also webs of high strength, without which there’s a risk of bursting of the filled bags and which lowers the packaging weight limit.

Another problem in presently known methods of bottom closing of pillow shaped bags is that it requires additional items like multifilament yarn for bags made by stitching or another closing strip which is to be fixed at bottom of bag either by hot air welding or gluing. This is another economic disadvantage of presently known methods of bottom closing of bags.

The above described sealing method are well known method in the industry for both bags made from tubular fabric as well as fabric obtained by making flat fabric into tube from the tuber machine.

An important aspect of bag formation is how easily one can close it. Currently filling valves are provided during the sealing process of one of the open ends whereby bags can be filled after seals have been made. Alternatively, a filled bag may be sealed at its open end using techniques such as stitching, gluing it or hot sealing it.

There are many bag sealing techniques and bags made using them. One such technique is disclosed in US Patent 10035637 (‘5637) which discloses details of construction of multilayer plastic bags. The patent (‘5637) further discloses a plastic bag with side gusset sealed by applying amorphous alphaolefm adhesive on the various layers of the fabric and then closing it. The patent (‘5637) does not disclose any apparatus or automated bag formation machine for formation of such which result in the decrease in productivity. One disadvantage of this disclosure is that it doesn’t advise on how to control the amount of adhesives. The use of too much adhesive in each layer will hinder the process of folding in an automated line so bag of such type is near to impossible to be made in a high production continuous line. Another bag sealing technique is disclosed in European Patent EP 1899235 (‘235). The patent (‘235) relates to a side gusset bag which is produced from a polyolefin material and which comprises a tubular section including the front walls and the sidewalls of the bag, the sidewalls comprising side gussets. The tubular section is also provided with a bottom section at the end of the tubular section, where the material of the tubular section is folded by 180° about an axis extending substantially at an angle to the side gussets.

The bag is characterized by a sheet that covers at least parts of the folded section. However, this patent does not disclose any apparatus or automated method of making such bag. Also, use of additional sheet for cover the bottom folded end will eventually add to the weight of the bag.

Further, another US patent US4008850 (‘8850) discloses formation of gusset type bag with sealing ends. The patent (‘8850) discloses a sift-proof, leak-proof bag formed from a gusseted fabric, multi-walled tube of paper having stepped plies and bag walls at each end of the tube for attachment to the bag side walls to provide closed bag ends. The patent (‘8850) used paper rather than polymer or plastic fabric for bag formation, which is quite easy to manufacture, yet patent does not disclose any automated method of making such bag. Further, the main drawback of patent (‘8850) is making multi-layer cutting or profiling at the edges before folding and sealing which eventually reduces productivity.

Yet another aspect of the bag formation is after filling, the bag can be placed in the upright position such its bottom can be flat to the surface on which it is kept. This ensure easy upright stacking of the bags and is good for displaying the bag for shopping commodities.

There is therefore a need for a bag/sack and a method to produce it which overcomes these drawbacks so that the integrity and strength of the web material is not unduly compromised and at the same time the seals are strong and integral.

Objects of Invention:

The main object of the present invention is to provide an apparatus and a method for manufacturing bag which has at least at one end closed.

Another objective of the present invention is to provide a bag with easy closing feature after filling

Yet another objective of the present invention is to provide a bag with an integrally closing bottom that reliably seals the bag after filling.

Further objective of the present invention is to provide an apparatus for making integral closing mechanism on automated bag manufacturing lines that operate at high speed.

Another object of the present invention is to provide a woven packing bag with easy upright stacking, quick filling and closing operation.

Further objective of the invention is to provide a method and an apparatus for manufacturing woven packing bag which can have at least one end a valve at the top.

Another objective of the present invention is to provide an apparatus which can be integrated with the automated bag making line

Brief Description Of Figures:

Figure 1 shows an apparatus of the present invention for producing a bag with a sealed bottom.

Figure 2 shows various processes involved in bag formation with bottom end sealed Figure 3 shows bag of the present invention with bottom sealed end

Figure 3 A shows bag of the present invention with bottom sealed end and top end stitching Figure 3B shows bag of the present invention with bottom sealed end top end with valve and stitching

Figure 3C shows bag of the present invention with bottom sealed end and top end with valved and sealed

Figure 4 shows an apparatus of the present invention for producing bag with top strip for closing after filing and bottom sealing.

Figure 5 shows various processes involve in woven packing bag formation with top end easy closing and bottom end sealed

Figure 6 shows a bag of the present invention with bottom sealed end and top end with easy close List of Parts:

1. Tubular web cut piece II) Second mid-layer

1 A. First open end or top end 2. First sealing device IB. Second open end 3. Apparatus of invention

IC. End of First fold 4. Conveyor

ID. End of Second fold 35 5. Tubular fabric

IE. End of folded layer of 6. Cutting unit fabric 7. Opening unit

IF. Top layer 8. First penetrator

IG. Bottom layer 9. Second penetrator 1H) First mid-layer 40 10. Conveyor belt 11. First folder 22. Roll

12. Second folder 23. Strip cutter

13. Second sealing device 24. Side cutting unit

14. First fold 20 25. Filled Bag

15. Second fold 26. Folded strip

16. Stacking unit 27. Removable sealing agent

17. Press tool 28. Block

18. Sticking agent 29. Suction opening

19. Bag 25 30. Cut point

19A. Front portion 31. Bag of first kind 19B. Side portion 32. Bag of second kind 19C. Bottom portion 33. Bag of third kind 19D. Open end 34. Bag of fourth kind 19E. Closed end 30 35. Edge of conveyor 20. Pivot 36. Suction device

21. Strip

Summary Of Invention: The present invention provides for an apparatus and a method for producing a bag with integrally formed bottom. The invention further provides an apparatus and method for provide easy closing to a bag after filling. For the purpose of this description, the terms web, web material, or fabric are used synonymously. The bags may be block-bottom type, may have a valve, or may be of pillow type and made from a web sheet with more than one layer, comprises of a front wall, a back wall, a first side wall, a second side wall, an interior surface, an exterior surface, a top end, and a bottom end. The web sheet comprises a first layer made of a woven polymer or optionally non-woven polymeric web and a second layer made of adhesive coating or extrusion coating which is made from any material such as polypropylene, polyethylene, polyethylene terephthalate, polyamide, or any combination thereof, or paper.

Optionally, a third layer is provided which comprises oriented polypropylene, biaxially-oriented polypropylene, oriented polyethylene, biaxially-oriented polyethylene, oriented polyethylene terephthalate, biaxially-oriented polyethylene terephthalate, oriented polyamide, biaxially-oriented polyamide, coated paper or any combination thereof.

In an embodiment, the third layer is of BOPP lamination film with high end graphics or printing, such that it formed three layered structured bags. In further Embodiments, the bag comprises of at least two layers such that first layer is made of a woven polymer or optionally non-woven polymeric web over which a second layer which is formed by coating is laid. Further, it is possible that the second layer comprises a printed area such that printing can be done by use of any such known printing methods performed by any other printing machine.

The tubular fabric can be of gusset type which is made from flat fabric then processed in the tuber machine or can be tubular fabric obtained directly from the loom. The main advantage of using gusseted fabric obtained from tuber machine is that there is no side crease of lamination formed, rather smooth surface is obtained where one can perfectly do branding.

But nevertheless, present invention provides solutions for any type of cut piece of fabric.

The terms used herein such as first end and top end are synonymous, and the terms second end and bottom end are also synonymous. Such terms are used so that the in case of cut piece the fabric is denoted by first end and second end while when the bag is made the fabric is denoted by top end and bottom end. In an automated bag making line, various processes are carried out by which a tubular or flat fabric is converted into bag. Some of such processes are:

• Web roll feeding means wherein woven or non-woven fabric roll is loaded to feed the fabric in forward direction

• Web edge guiding and unwinding means wherein the fabric is guided over rollers and unwinds from the fabric roll

• Web fabric preparatory means wherein

Preparatory means optionally consist of web perforation means which removes all the air traps between the layers of the fabric for smooth operation. Some examples of the preparatory means are as under: o Index hole punching means o Web cleaning means

Optionally sensing means sensing the print mark in case of printed fabric.

Web cut length cutting means which cuts the fabric in required bag length.

In the present invention, the tubular fabric after cutting by the cutter is made to transfer into the traverse direction such the first and second open end of the cut piece are now parallel to the edge of the traverse unit. The first open end of cut piece is opened such that its two layers are individually sucked by the opening unit to form a mouth. Simultaneously, a pair of penetrators swivels about the pivot and make a cut at the side wall of the cut piece at a predetermined distance. Then the cut piece is made to transfer under the first folding unit where the top layer of the cut piece is folded to form a first fold and simultaneously a sealing agent is applied at a distance “r”. The distance “r” is a smallest distance required for the inner wall of the fold to cover the layer of cut piece (this is defined in the later stages of the application). Now the second fold is made by the second folding unit and bottom is sealed by passing over the press unit the bags thus formed are stacked over stacking unit and are send for further uses.

The top sealing unit can also be integrated with the apparatus of invention or can be driven alone.

The top sealing unit applies the strip over the layer of the bag during continuous movement of bag while processing bottom seal. The strip is divided into two with one area being pasted over the cut piece by sealing agent and another area which has special sealing substrate and can be removed after filling of the bag and pasted on another layer to seal the bag.

Optionally, the valve can also be introduced at the second open end and sealed by strip, in such case bottom remains same.

Thus, the bag obtained can be placed in the upright form after filling which is attractive in looking as the same is without any appearance of stitching.

Accordingly, the bag of the present invention comprises a tubular piece made of a fabric (1), of web material as herein described, the tubular piece is converted into bag having a closed bottom end, preferably by means of a hot sealing to form an integral bottom closing.

In another aspect, the present invention provides an apparatus for producing a bag with integral sealing. The apparatus can produce bags made from web material which may be woven fabric, non-woven fabric, optionally coated or laminated. Further aspect of the present invention is to provide a top easy closing to a bag such that top end can be closed easily before or after filling.

Detail Description Of Invention: Figure 1 shows apparatus of the present invention (3) which converts the tubular fabric (5) into finish product as bag (19). The tubular fabric (5) is particularly but not necessarily a gusset type which is obtained either from the tubular fabric weaved on weaving loom or can be obtained from flat fabric weaved on weaving loom then making tube in tuber machine. The tubular fabric (5) can be optionally BOPP laminated.

The tubular fabric (5) is conveyed on the conveyor (4) in the longitudinal direction of movement as shown by arrow. The tubular fabric (5) is cut into predetermined length by the cutter unit (6) into a tubular cut piece (1) such that first open end (1A) and second open end (IB) are obtained. Now the tubular cut piece (1) is made to travel in the traverse direction as shown by arrow.

Apparatus (3) also comprises of opening unit (7) such that it opens the layers of the tubular cut piece (1) to form a mouth. The opening can be performed by either pneumatically or by installing vacuum (suction) which sucks the upper and lower layers of the cut piece (1) apart from each other. In such condition the conveyor (4) has perforations (or holes) though which a constant suction is maintained by the suction devices (36) which hold the lower layer of cut piece (1). The suction devices (36) as shown in figure 1A can be high capacity blowers which creates vacuum by sucking the air and throwing the sucked air back into the environment. The top layer is held by the suction block arrangement which can be moved up to obtain a mouth opening. Such method is stop-and-go method where the cut piece (1) stops for a moment till the process of opening happens. Mechanical methods such as use of clippers for holding the layers of cut piece (1) is well known to person skilled in art.

The suction can further be performed in the automated form without stop-and-go. The suction device (36) which create suction in block (28) with suction opening (29). The block (28) is constructed in such a way that it is in form a curvature to form a smooth path of travel for the cut piece (1) as shown in figure 1A. As soon as the top layer (IF) is gripped by the suction openings (29) and the bottom layer is gripped by the conveyor (4) (which also has suction openings (29) so that the mouth is formed), simultaneously side cutting unit (24) which comprises of first and second penetrator (8, 9) are rotated about pivot (20) such that a cut is made at the cut point (30) on the first mid-layer (1H). Mid-layer is obtained when fabric is gusseted only. Gusset fabric has two inside layers called out as first mid-layer (1H) and second mid-layer (II).

The first and second penetrators (8,9) can be of identical construction which has a sharp edge such that it can cut the tubular cut piece (1) at a cut point (30).

Apparatus (3) also comprises of first folder (11) and a first sealing device (2) at a single station (i.e. the same station) to increase the productivity of the system as both the operation such as folding and gluing is done simultaneously on a same cut piece (1). The cut piece (1) is now made to enter into the first folder (11) which folds the top layer (IF) along with the second mid-layer (II), simultaneously first sealing device (2) dispense the sticking agent (18) over the surface of the top layer (IF) of the cut piece (1), thus the first fold (14) is made.

In one of the embodiments, before application of the sticking agent (18) the surface is corona treated or treated by any other method by which the adherence of sticking agent (18) on the surface becomes strong.

As shown in figure IB, a region ‘r’ is left after which application of sticking agent (18) dispense such that movement of first sealing device (2) is adjustable to and fro as shown by arrow with respect to the edge of the conveyor (35). Adjustment of first sealing device (2) is required such that sticking agent (18) can be positioned exactly by the first sealing device (2) after region ‘r’ on the cut piece of varied length very easily. Apparatus (3) also has second folder (12) which folds the bottom layer (1G) and pressed by the press unit (17) to form a close end (19E) and to form a second fold (15). The completed bag (19) with closed end (19E) and one end (19D) is transferred to the stacking unit (16) for further needful.

In one of the embodiments, the bag (19) can be made from tubular fabric without gusset.

In one of the embodiments, at side B, the apparatus (3) can be integrated or modified if bag (19) is to be featured with self-closing option at the top side or at first open end. As shown in figure 4, in addition to the apparatus (3) defined in figure 1, at side B, apparatus (3) comprises of second sealing device (13) situated near to the first open end (1A) at the side B such that it dispenses the sticking agent (18) over the top layer (IF) of the cut piece (1) .Further a strip (21) is unwounded from a roll (22) and stuck on the sticking agent (18) and simultaneously pressing it with the help of press unit (17). Here the word “simultaneously” is used explicitly such that plurality of operations is performed on the same cut piece (1) at the same station at a time.

The strip (21) is a special strip prepared out of woven fabric, first half of which is pre-coated along the width by a removable sticking agent (27) or a peel-off type cover and rest half is coated either by PE or PPE or any kind of plastic coating known to person skilled in art.

The half of the strip (21) which is coated with plastic film is pasted over the top layer (IF) at the open end (1 A).

Apparatus further comprises of a strip cutter (23) for cutting strip (21) after predetermined interval to remove connection between two bags. The bottom sealing is done the way as described for figure 1. The apparatus (3) as shown in figure 4 produces a bag of first kind (31).

In another embodiment, the apparatus (3) can be integrated or modified if bag (19) is to be featured with valve at the top side or at first open end (1 A) with stitching. In case of valved bags, the apparatus (3) at side B, comprises of valve formation unit and another folding unit at the first open end (1 A) flowed by stitching unit to produce a bag of third kind (33).

Further in another embodiment, the apparatus (3) can be integrated or modified if bag (19) is to be featured with valve at the top side or at first open end without stitching. Stitching unit described above can be replaced by hot welding or gluing system to produce a bag of fourth kind (34).

In yet another embodiment, bag (19) can be closed at the first open end (1A) by stitching which is done after filling of the bag to obtain a bag of second kind (32).

As shown in figure 2, the bag (19) formation involve following steps:

(A)From the web puller, to pull the tubular fabric (5) from the fabric roll in the longitudinal direction to the cutting unit(6);

(B)Now at the cutting unit (6), tubular fabric (5) is cut into predetermine length to from first open end (1A) and second open end (IB);

(C) , (D) Further, cut piece (1) is transferred to the opening unit (7) where top layer (IF) and bottom layer (1G) are opened to form a mouth (as indicated by Step C) and simultaneously, both first and second penetrator (8,9) rotates and cuts the bottom layer (1G) at cut point (30) at the side cutting unit (24) (as indicated by Step D). Opening unit (7) and side cutting unit (24) are at single station (i.e. the same station);

(E) , (F) At the second open end (IB), top layer (IF) is now folded by the first folder (11) (as indicated by Step E) and simultaneously sticking agent (18) is applied over the it by the first sealing device (2) (as indicated by Step F). First folder (11) and first sealing device (2) are at single station (i.e. the same station);

(G) Now, at the second open end (IB), bottom layer (1G) is folded by the second folder (12) over the top layer (IF).

(H) Press tool (17) presses the folded bottom portion (19C) of the cut piece

(1) to form a strong bond

(I) Bag (19) thus formed conveyed further to the stacking unit (16).

In the above method, as shown in the figure 2, various processe are performed simultaneously which is denoted by broken rectangular box.

In yet another embodiment, at step (C), (D) the valve formation device makes a valve at the first open end (1A) and at step (E), (F) folding and stitching of the first open end (1A) happens to form top close end to obtain a bag of third kind (33) as shown in figure 3B.

In further embodiments, at step (C), (D) the valve formation device makes a valve at the first open end (1A) and at step (E), (F) folding and sticking of strip (21) at the first open end (1A) happens to form top close end to obtain a bag of fourth kind (34) as shown in figure 3C.

In another embodiment, as shown in figure 5, the above bag (19) which is termed as bag of first kind (31) formation involve following steps:

(A): From the web puller, to pull the tubular fabric (5) from the fabric roll in the longitudinal direction;

(B): Now from the cutting unit (6), tubular fabric (5) is cut into predetermine length to from first open end (1A) and second open end (IB); (C), (D) , (D’): Further, cut piece (1) is transferred to the opening unit (7) where top layer (IF) and bottom layer (1G) are opened to form a mouth (as indicated by Step C) and simultaneously, both first and second penetrator (8,9) rotates and cuts the bottom layer (1G) at cut point (29) at side cutting unit (24) (as indicated by Step D). Opening unit (7) and side cutting unit (24) are at single station. Further, at first open end (1A) second sealing device (13) dispense the sticking agent (18) also (as indicated by Step D’);

(E) , (E’) , (E”): At the second open end (IB), top layer (IF) is now folded by the first folder (11) (as indicated by Step E) and simultaneously sticking agent (18) is applied over the it by the first sealing device (2) (as indicated by Step E”). First folder (11) and the first sealing device (2) are at single station. Further, at first open end (1A), the strip (21) is applied which is unwounded from the roll (22) at the same station (i.e. at the same station - as indicated by Step E’);

(F) , (F’): Now, at the second open end (IB), bottom layer (1G) is folded by the second folder (12) over the top layer (IF) (as indicated by Step F). Further, strip (21) is cut at predetermine interval by strip cutter (23) at a single station - i.e. the same station (as indicated by Step F’);

(G): Press tool (17) presses the cut piece (1) to form a strong bond;

(H): Bag (19), thus formed is bag of first kind (31) is conveyed further to the stacking unit (16).

In the above method, as shown in the figure 5, various processes are performed simultaneously which is denoted by broken rectangular box.

The bag (19) with one end of the bag open as shown in figure 3 is obtained by inventive apparatus (3). The bag (19) has an open end (19D) and a closed end (19E) with at closed end (19E) multiple folds to obtained end of first fold (1C) and end of second fold (ID) such that end of folded layers of fabric (IE) is obtained, which is bonded by the sticking agent (18). Bag (19) further comprises of first mid-layer (1H) and second mid-layer (II) in case of gusset fabric. But in case of tubular fabric without gusset there is no presence of mid-layers.

In another embodiment, bag (19) can be obtained as bag of first kind (31) as shown in Figure 6. The bag (31) comprises of bottom closed end (19E) and top open end (19D), with sides (19B) and front portion (19A) as shown. The bottom portion (19C) of bag (30d) comprises of integral closing with end of first fold (1C) and end of second fold (ID) such that at least two folds are required to construct the bag (31). Further, bottom sealing is done by the sealing agent (18) applied at the location shown in figure 6 as well such that end of folded layer (IE) is obtained. At the first open end of the bag (1A), strip (21) is applied which has an area of removable sticking agent (27) which is folded and stick over another layer of bag (31) to close it after filing making provision of easy closing.

The bag (31) can be made attractive in looking with various brand printing positions with the feature of standing in upright position after filling.

In yet another embodiment, as shown in figure 3A, bag (32) which is filled bag (25) is shown with top as stitched which is done after filling having identical bottom (19E) as made in bag (19).

In further embodiment, as shown in figure 3B, bag (33) is formed by making valve at top and closing it with stitching having identical bottom (19E) as made in bag (19). The bag (33) is formed before filling as the valve provided is used to fill the material.

In yet another embodiment, as shown in figure 3C, bag (34) is formed by making valve at top and closing it with strip (21) having identical bottom (19E) as made in bag (19). The bag (33) is formed before filling as the valve provided is used to fill the material. While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.