WO2022096974A1

WO2022096974A1 - An apparatus and a method for manufacturing block bottom bags, and a block-bottom bag

Info

Publication number: WO2022096974A1
Application number: PCT/IB2021/059651
Authority: WO
Inventors: Vedant AGGARWAL
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-11-04
Filing date: 2021-10-20
Publication date: 2022-05-12
Anticipated expiration: 2023-05-04
Also published as: AR123986A1; TW202227262A

Abstract

The invention relates to an apparatus and a method for manufacturing block bottom bags, and a block-bottom bag. A single apparatus to make block bottom bags is disclosed incorporating features such as inspecting the thermoplastic film for flaws, transferring the thermoplastic film at high speed, rejecting defective parts of the thermoplastic film without interrupting the production flow, and more, in a holistic manner. Accordingly, the apparatus of invention has a thermoplastic film preparatory means (b), an inspection and sensing means (c), a thermoplastic film cut length cutting means (d), a transportation means (e), a defect rejection means (f), a top and bottom edge opening means (g), a valve patch application means (h), a top and bottom end folding means (i), a cover patch application means (j), a stacking means (k), and a main automation and controlling means (1) consisting of controlling unit (41) for controlling the process of manufacture of bag (32) from film.

Description

AN APPARATUS AND A METHOD FOR MANUFACTURING BLOCK BOTTOM BAGS, AND A BLOCK-BOTTOM BAG

Field Of Invention

The invention relates to an apparatus for manufacturing block bottom bags from tubular film using thermal welding such that bag is recyclable.

Background Of Invention

Thermoplastic bags are already known which are formed from a tube of thermoplastic material which is cut transversely to the axis of the tube and then joined together along the lines of cutting. The main disadvantage of these known bags is that when filled they assume the shape of a pillow or cushion, a shape which is disadvantageous when it is desired to stack these bags, as well as being wasteful of material since the "pillow comers” will hold only a small volume of material.

"Block-bottom¹ or parallelepipedal bags on the other hand known to have, been constructed in the past using one or more plies of paper or like material and using an adhesive to secure the bottom-forming members in place. The bottom forming members are usually formed by suitable cuts and folds in the opposite ends of the blank or tube from which the said bags were constructed, which are not completely recyclable as per current environmental norms/standards.

The bases or ends of the block bottom sacks or bags are typically formed in machines where flat placed tubular pieces of thermoplastic film are folded into a block shape at their ends. The bag making machines typically comprise a number of stations designed to carry out specific functions that finally lead to make a complete block bottom bag. However, due to evolution of these machines over the past few decades, especially due to the increased high speed of the machines, a number of new aspects need to be looked at. Such as lesser time for changing roll at the unwinding station to reduce the production loss, quick and even cutting and transfer of cut piece from one direction to another, good bonding of patch to the top and bottom to form a bag and efficient transportation, etc. are some of the main aspects of the machines to be looked at. A typical machine comprises processing stations such as station for opening out the ends of the continuously conveyed tubular sections into the bottom squares forming the open bottoms, and for fixing and closing the bottoms with the insertion of valve leaves or tubes, and for attaching bottom cover sheets onto the closed bottoms.

With the advances in packaging requirement and customer demand, many new features are required to be incorporated on bag conversion machines. Further, conventionally, block bottom bag machines are used to process web of woven fabric, such bags are prone to moisture and are not perfectly water resistant, thus there is a requirement of waterproof sacks with highest product protection. Due to the limitations of the known technologies of such machines and the processes they employ for working with woven sacks with many modification and adaption in units and parts are required to produce a bag with thermoplastic film. Some of these relate to aspects such as high speed unwinding and edge-guiding of thermoplastic film roll; pre-treatment of thermoplastic film surface like perforation, anchor hole; inspecting the thermoplastic film for flaws; high speed cutting; transferring the thermoplastic film at high speed, rejecting defective parts of the thermoplastic film without interrupting the production flow, and more, which are not considered in a holistic manner. Several such aspects have been considered individually, however, there is not a single apparatus that incorporates all these aspects. Also, synchronous controlling of all these units working as a single machine is a huge challenge.

In one of the patent applications CN1201923C (‘ 1923), it discloses a double layered polyethylene valve bag and its preparation method. Such double layered bag is made by a complex method such that sheathing polyethylene internal and external tubes with pinholes, making the pinholes on internal and external tubes not being in the same position, folding the long circular mouths of two ends of double-layer tube into multi-layer multi-edge geometric upper and lower bottom surfaces, installing a valve port on the short edge of upper bottom surface, sticking a layer of face fabric on the upper and lower bottom surfaces, and then making the heated high-pressure mould implement one-time multi-edge pressure welding of the lower bottom surface sheathed on the sheathing mould and the upper bottom surface lined with lining mould, so that the double-layer exhaust double-bottom three-dimensional rectangular polyethylene valve bag can be made up. However,, the said patent (‘ 1923) does not discloses any apparatus for manufacturing the same or an automated process of manufacturing of bags to increase the production rate.

Another patent application CN102328774 (‘774) discloses packaging bag, to a square-bottom valve bag containing thermoplastic plastics and a manufacturing method thereof. In the said Patent (‘774), the sealing at the end is done by hot air and the cover patch which is applied at the ends to seal the bag can be of plastic or cloth, such kind of bonding of different materials require precision and therefore it is time consuming, which will eventually lower the production rate. Further patent (‘774) does not discloses any apparatus for manufacturing the same or an automated process of manufacturing of such bags.

The present invention is distinguished from these prior arts arrangements by a fact that “block-bottom¹ or parallelepipedal bag which is wholly constructed of heat-sealable thermoplastic material with the bottom being formed and joined to the side walls of the bag by thermal welding steps non-contact type. Further, the bags of the present invention may be formed of one or more plies of thermoplastic material. Further, there is therefore also a need to provide a single apparatus to make block bottom bags that incorporates features such as such as inspecting the thermoplastic film for flaws, transferring the thermoplastic film at high speed, rejecting defective parts of the thermoplastic film without interrupting the production flow, and more, by considering them in a holistic, seamless and advantageous manner.

Objects of Invention:

The main object of the present invention is to provide an apparatus to make block bottom bags from recyclable thermoplastic film.

Another object of the present invention is to provide an unitary apparatus adapted to make recyclable thermoplastic film based block bottom bags that incorporates features such as inspecting the thermoplastic film for flaws, transferring the thermoplastic film at high speed process , rejecting the defective parts of the thermoplastic film without interrupting the production flow, thermal welding of valve patch and cover sheet, and more, by considering them in a holistic manner.

A further object of the present invention is to provide a apparatus that is suitably adapted for processing of thermoplastic film to form block bottom bags.

Yet another object of invention to provide an automated apparatus for manufacturing of block bottom bag from recyclable thermoplastic.

Yet another object of the present invention is to provide an automated process of manufacturing of block bottom bag from recyclable thermoplastic

Brief Description Of Figures:

Figure 1 andl A show the apparatus of the present invention in a schematic form Figure 2 shows the welding/sealing device Figure 3 shows the working principle of welding/seahng device

Figure 4 shows the block bottom bag made from recyclable thermoplastic film

Summary Of Invention:

Thermoplastic film can be produced from blown film extrusion machine which involves a process of extrusion of plastic through a circular die, followed by “bubble -like” expansion. Mainly polyethylene (HDPE, LDPE and LLDPE) but a wide variety of other materials can be used as blends with these resins or as single layers in a multi-layer film structure, these include PE, PP, PA and EVOH to form thermoplastic film.

Such kind of film and bags made out of it are widely used in Industry packaging (e.g. shrink film, stretch film, bag film or container liners), Consumer packaging (e.g. packaging film for frozen products, shrink film for transport packaging, food wrap film, packaging bags, or form, fill and seal packaging film), Laminating film (e.g. laminating of aluminium or paper used for packaging for example milk or coffee), Barrier film, films for the packaging of medical products, Agricultural film (e.g. greenhouse film, crop forcing film, silage film, silage stretch film). According to invention the apparatus and process to make block bottom bags using suitable thermoplastic film is disclosed now.

The thermoplastic film which are flimsy in nature needs to be treated and handled very precisely during bag manufacturing. The various processes involve needs an accurate and specific functionality so that production rate is high preferably 120- 140 bags per minute or more, and at the same time bag of desired strength is achieved which when filed with 40-50 kg of material can withstand the drop test.

The apparatus of the present invention has the following stations or units with their specific functionalities: a) a thermoplastic film-roll feeding means which comprises of a thermoplastic film edge guiding and unwinding unit b) a thermoplastic film preparatory means that in itself comprises

• a preparatory means optionally consist of thermoplastic film perforation means

• index hole punching means, and

• a thermoplastic film cleaning means c) an inspection and sensing means which comprises of inspection unit d) a thermoplastic film cut length cutting means consisting of high speed cross-cutter e) a transportation means with transfer unit f) a defect rejection means to eliminate defective pieces into rejection zone g) a top and bottom edge opening means comprises of

• an optional the edge opening means vertically positioned

• an opening means having rotary mechanism h) a valve patch unit for storing, conveying and thermal welding/sealing means of valve patch i) a top and bottom folding means j) a cover patch unit for storing, conveying and thermal welding means of cover patch k) a stacking means l) a main automation and controlling means

In some embodiments of the invention, some of the aforementioned stations are combined.

List of Parts:

1. Thermoplastic film roll

2. Cut piece of film

2 A Top end

2B Bottom end

3. Unwinder unit

4. Inspection unit

5. Perforation unit

6. Perforation roller

7. Cutting unit

8. Transfer unit

9. End opening unit

10. Valve patch unit

11. Valve patch cut piece

12. Valve patch roll

13. Patch welding unit

14. Top folding unit

15. Bottom folding unit

16. Cover patch unit

17. Cover patch cut piece

18. Cover patch roll 19. Frame

20. First idler roller

21. Second idler roller

22. Third idler roller

23. Pressure roller

24. Master cutter

25. First sensor

26. Second sensor

27. Hot drum

28. Suction roller

29. Impression roller

30. Hot gun

31. Stacker unit

32. Bag

33. First end

34. Second end

35. Axis

36. Valve patch

37. Cover patch

38. Micro pores

39. Nozzle

40. Ejection zone

41. Controlling unit

42. Emitter

43. Receiver

44. Punching means

45. Shaft

(a) Feeding means

(b) Preparatory means

(c) Inspection and sensing means (d) Cutting means

(e) Transportation means

(f) Rejection means

(g) Top and bottom edge opening means

(h) Valve patch application means

(i) Folding means

(j) Cover sheet patch application means

(k) Stacking means and

(m) Main automation and controlling means

Detail Description Of Invention with respect to figures:

In accordance with the present invention, there is provided an apparatus for manufacturing cross bottom sacks from laid-flat tubular cut piece of the film (2) made from thermoplastic film roll (1).

As shown in Figure 1, 1A, apparatus of invention which comprises of various units that are listed below, and which have specific functionalities: a thermoplastic film-roll feeding means (a) which consisting of

• an unwinding unit (3) for unwinding the film role

• optionally a thermoplastic film edge guiding (not shown)

• thermoplastic film preparatory means (b) consisting of a preparatory means optionally consist of thermoplastic film perforation unit (5)

• a preparatory means optionally consists of index hole punching means (44) , and a thermoplastic film cleaning means (not shown) an inspection and sensing means (c) consisting of inspection unit (4) a thermoplastic film cut length cutting means (d) like high speed crosscutter and an inclined cutter unit (7) a transportation means (e) consisting of

• a traverse transfer unit (8) for transferring film from X to Y direction a defect rejection means (f) which eliminates the defective film cut pieces to ejection zone (40) a top and bottom edge opening means (g) consisting of end opening unit (9) with

• an optionally the edge opening means vertically positioned

• an opening means having rotary mechanism a valve patch application means (h) consisting of a valve patch unit (10) for storing, conveying and thermal welding of valve patch onto the one end of the film a folding means (i) for top and bottom folding (14,15) of film a cover patch application means (j) consisting of a cover patch unit (16) for storing, conveying and thermal welding of cover patch a stacking means (k) consisting of stacker unit (31) for storing the processed bag made of film a main automation and controlling means (m) consisting of controlling unit (41) for controlling the process of manufacture of bag (32) from film Some of these units can be called out common in construction which are placed at the sides A & B as can be seen from figure 1. The film movement is shown by the arrows in the X and Y direction, the main purpose of change in direction of bag from X to Y is such that the side of the bag can be processed easily.

The thermoplastic film roll feeding means (a) supplies the thermoplastic film roll (1) which is supported on an unwinder unit (3). The roll is unrolled in form of tubular film. The unwinder unit (3) can be single station or multi station. Here single and multi-station depicts the number of rolls which can be mounted on the unwinder unit such that an ideal roll is mounted opposite to the active roll. During roll change over the operator quickly changes from empty roll to the filled roll which minimises the lead time of roll changing. Thus, the main aspect of multi station unwinder unit is that presence of plurality of stations side by side having unique shaft (45) for each station such that multiple rolls can be loaded, the said extra rolls can be utilised during change over.

Now, the tubular film is made to pass through the thermoplastic film preparatory means (b) which comprises of a perforation unit (5) where at least one set of perforation roller (6) is present. The perforation roller (6) comprises of plurality of needle shaped fins projecting outwards which are termed as nano perforation due to their small size preferably in the range of 0.5-0.7 mm diameter. These needles spread over the roller preferably at a density of 80-90 needles per square centimetre and form a cluster. Due to the cluster of needles and their dense nature, it creates nano perforation holes in the film.

The term nano in nano perforation is well known by person skilled in art such that it signifies the size of the needle such that it is very small when compared to the normal size used for manufacturing of bag from film. As an example, the normal size of needle diameter preferably can be in range of 1- 1.5 mm where as nano size of needle diameter preferably can be in the range of 0.5-0.7mm. These holes are essential in removing trapped air inside the tubular thermoplastic film during filing of the bag.

Further, optionally index holes are made using punching means (44) and cleaning the thermoplastic film is done. The cleaning can be done by jet of air which is passed over the tubular film at low output speed.

The tubular film is now passed through an inspection and sensing means (c) which comprises of inspection unit (4) such that any defects in the film can be monitored and the defective area can be removed after cutting by the cutting unit (7) before being processed to the side opening unit (9). The inspection unit (4) further comprises of an emitter (42) and receiver units (43) which capture the image of the thermoplastic film passing through it and any change in the colour of the said thermoplastic film or any crack or breaks is indicated by the emitter / receiver unit and defects are detected. The flaw locations are sensed and stored in a database in the controlling unit (41).

In one of the embodiments, an inspection and sensing means (c) is placed before the preparatory means (b). As soon as the defective tubular film is detected by the inspection unit (4) the machine will stop, thereby stops the advancement of the tubular film further into the perforation unit (5). Such activity will increase the life of the perforation unit (5) as only the non- defective film is made to pass through the perforation unit (5). The defects can be of nature like bulge, tear or any kind of protrusion which will hamper the perforation needles.

In order to make a desired cut length of bags, the thermoplastic film is made to pass through thermoplastic film cut length cutting means (d) which comprises of cutting unit (7) where the film is cut into pieces of predetermined length, which typically depends on the bag size and shape. The cutting of the thermoplastic film is done according to the feedback which is stored in a database. The tubular film which is now cut by the cutter unit (7) into desired length of cut piece (2) with top and bottom end (2A,2B) is obtained. Generally, cold cutting method is used to cut the film into desired cut piece (2) which has an advantage over the hot cutting operation. During hot cutting operation the upper and lower layer of the film is sealed together which required additional efforts to be separated in the later stages.

High speed cutter unit (7) is incorporated to increase the speed of the cutting operation by 25-30% i.e. 120-140 bags / min. Here, a signal from the inspection unit (4) is sent such that the defective pieces or the area containing defects are cut without wasting the film. Thus, the cutting machine is adapted to cut the thermoplastic film at required process speed with high precision. Further, the said adaption of the cutting unit (7) is done due to the cross cutting operation by the cutter. Due to such operation the machine can run continuously without lowering down the speed.

In the conventional bag cutting systems, the movement of cutter is perpendicular to the movement of the cut piece which restricts the machine to operate at high speed because in each cutting stroke, the machine must lower down the speed such kind of mechanism can also be termed as stop and go process.

The cut pieces (2) are transported to further stations by transportation means (e). The said transportation means comprises of traverse transfer unit (8) which includes a positive grip transfer mechanism that achieves transport at a much higher speed than the system where cut pieces (2) are transported on a single conveyor in a single plane. Such transfer unit (8) is capable of transferring cut piece of thermoplastic film (2) from X direction to Y direction at greater speed without slowing down the machine. The defective piece of thermoplastic film which is sensed by the inspection unit (4) is cut by the cutter and are removed from the mainline processing via defect rejection means (f) into the ejection zone (40) such that only defect-free pieces continue their transport to further downstream stations.

In one of the embodiments, the traverse transfer unit (8) can be constructed in such a way that the cut piece (2) does not stop but can be transferred in the inclined pull of fashion. This inclined pull of fashion makes the cut piece (2) to move gradually in the inclined plane and changes the direction from X to Y.

The defect-free pieces are now transferred to edge opening means (g) which comprises of end opening unit (9) where the top and bottom ends (2A,2B) are opened for the purpose of fold making. The opening of the ends may take place using a rotary mechanism or a mechanism that operates in a vertical plane. The sides before subjecting to the rotary mechanism is opened by the suction means or any kind of means such as clipper arrangement which can open the two layers of film. The opened layers of film is subjected to the profiled structures which rotates in such a way that during the movement in Y direction the bag is opened. The end opening station (9) are situated both at the side A as well as side B such that the identical opening of the top and bottom end of the cut piece of film (2) is obtained.

At the bottom end (2B) of the cut piece of the film (2), a valve patch (11) is now pasted. A valve patch application means (h) comprises of a valve patch unit (10) which further comprises of valve patch roll (12) which is mounted on a shaft (45) which is free to rotate such that the supply of the valve patch (36) is done continuously and smoothly. Valve patch unit (10) further comprises of a patch welding unit (13) which cuts the valve patch (36) into valve patch cut piece (11) of desired length and paste it over the bottom end of the cut piece of film (2). Further, more details of the patch welding unit is shown in figure 2 which is described in detail in the later stage of the description in the specification. The valve patch (11) can be of a film of same material as of the cut piece of the film (2) or can be manufactured from composite materials which provide enough strength to the valve and can adhere with the substrate firmly. The fixation of the valve patch (11) with the cut piece (2) can be done by any kind of means such as hot welding, hot melt gluing or by using ultrasonic methods.

Cut pieces (2) with opened ends are sent to folding means (i) which comprises of top folding unit (14) and bottom folding unit (15) to make folds that form the bottoms of the block-bottom bags. Both top and bottom folding units (14,15) are identical in construction and are placed at side A and side B respectively.

Further, the folded ends of cut piece (2) are provided with cover sheets to seal the bag ends forming sealed block bottom bag. So folded ends of cut piece (2) is transferred to the cover patch application means (j) which comprises of a cover patch unit (16) which further comprises of cover patch roll (18). These cover patch rolls supplies cover patch (37) to the bottom and top end of the folded cut piece of film (2) separately. This individual supply of the cover patch (37) can be facilitated by providing two cover patch roll (18) which is identical in construction and are mounted on a single frame. The cover patch (37) which is supplied from the cover patch roll (18) is made to cut into cover patch cut piece (17) into desired length and are pasted over the top and bottom of the cut piece of the film (2). Such mechanism of cutting and pasting is done by the patch welding unit (13).

The apparatus of the present invention comprises of plurality of patch welding unit (13) such that the method of pasting patch can be done individually at different desired stations. The bag (32) now formed is conveyed further by stacker means (k) into the stacker unit (31) at the desired location for stacking.

All the processes parameters at each unit level form (a-k) are stored in the main automation and controlling means (m) as a data base and provide feedback to the different unit such that the units can function and can be altered in operation individually.

In one of the embodiments, the apparatus of the present invention can produce a thermoplastic block bottom bag using following units only:

• unwinding unit

• cutting unit

• traverse transfer unit

• top and bottom end opening unit

• Valve patch application unit

• Top and bottom folding unit

• Cover patch application unit, and

• Stacking unit

In another embodiment, the optional units such as perforation unit, inspection unit and rejection unit will enhance the speed of the machine such that defective cut pieces of thermoplastic film can be sensed and ejected easily from the main production line.

Figure 2 shows a patch welding unit (13), which is identical in construction for application of both valve patch (11) and cover patch (17) but are placed at different locations as can be seen from figure 1. The patch welding unit (13) comprises of frame (19) on which first idler roller (20), second idler roller (21), third idler roller (23) are mounted such that it provides tension to the patch which is unwounded from the roll (12,18). A pressure roller (23) is also mounted on the frame (19) such that it applies little pressure on the patch (36/37) at first end (33) and hot drum (27), master cuter roller (24) is present at the second end (34) so that cutting of the patch (36/37) can be done properly. The master cutter roller (24) contains a set of blade or sharp knife to cut the patch into piece by rotating about the axis (35). Hot drum (27) preheats the patch cut piece (11/17) so that in the later stages the patch can be pasted over the cut piece of film (2) with good adhesion.

A first sensor (25) is provided to sense the edge of the patch (36/37) such that any lateral displacement of the patch (36/37) can be corrected. A second sensor (26) is provided to sense the print mark if any such that the patch is cut at a predetermined length by sensing the print mark.

The aforementioned print mark is pre-printed on the patch (36/37) at a predetermined length. This predetermined length is the length of the patch (L) required for covering the top and bottom folded end of the bag (32) as shown in figure 4. The print mark sensor or second sensor (26) is specially designed to recognise the prints and command the master cutter (24) to cut the patch (36/37) at predetermined length.

In one of the embodiments, the apparatus of the present invention can produce a thermoplastic film bag (32) without using first sensor (36) as well. In such case a lateral displacement of the patch (36/37) may be observed which can hinder the quality of the bag (32) produced.

In another embodiment, the apparatus of the present invention can produce a thermoplastic film bag (32) without using second sensor (26) for the bag (32) produced from the non-pnnted thermoplastic film. The non-pnnted film does not comprise of a print mark after every cut length position or printed area. The basic significance of the print mark sensor (26) is that it senses the print mark and cut the film into desired length such that the printing of the film is not hampered. in yet another embodiment, the position of the idler rollers (20,21,22) can be altered in position such that a tension is maintained in the patch (36/37).

Valve patch cut piece (11) / cover patch cut piece (17) is sucked by the suction roller (28) such that it is conveyed and laid on the cut piece of the film (2) perfectly without any lateral displacement. However, suction cylinder (28) comprises of plurality of micro pores (38) through which suction is created. As shown in Figure 3, hot gun (30) through nozzle (39) throws a gust of air between the patch (11/17) and cut price of film (2) such that it creates a heating zone. The temperature of the heat zone can be regulated by regulating the amount of air to the thrown by the hot gun (30). The temperature of the heating zone is kept just below the melting temperature of the film or more preferably plastic i.e. in the range of 80-100 ° or more preferably 95° such that film (2) and patch (11/17) does not melt but creates a good bonding. A support or impression roller (29) is present which provides a base to the film (2) and provides a positive drive to the film (2). Once the cover sheets are in place, the block bottom bags are ready to be transported to stacking stations (31).

All operations are controlled in synchronous manner using electronic control and automation system. The main control system has facility for input of required control and process parameters through human machine interface. In one embodiment some of the stations may operate manually. Figure 4 shows bag (32) with block bottom end made from thermoplastic film cut piece (2) with valve patch cut piece (11) at one end and cover patch cut piece (17) at another end.

In accordance, present invention is distinguished from the prior art arrangements by a “block-bottom¹ or parallel epipedal bag is wholly constructed of heat-sealable thermoplastic material with the bottom being formed and joined to the side walls of the bag with external cover-sheet/sealing sheet using non-contact type thermal welding steps. The bags of the present invention may be formed of one or more plies of thermoplastic material. Further, the film material of bag body and its sealing sheet can be of similar type or different type.

The present invention also discloses a method for manufacturing of the block bottom bag from thermoplastic film involves following steps:

• The thermoplastic film roll (1) is made to unwind from the unwinder unit (3).

• The film now enters into the perforation unit (5) where nano preformation marks are made onto the film by the perforation roller (6).

• Further, the film is made to enter and is inspected in the inspection unit (4)

• Inspected film is cut into desired length or cut piece (2) by cutting unit (7) such that top end (2A) and bottom end (2B) is created which are opened.

• Cut piece of film (2) is transferred from X direction to Y direction by the transfer unit (8). • Opening of the film (2) at the end is done by end opening unit (9).

• Further, the valve patch cut piece (11) is pasted onto the bottom end (2B).

• The valve patch cut piece (11) is processed by cutting valve patch roll (12) into desired length by the patch welding unit (13).

• Now the top and bottom end (2A,2B) of the cut piece of film (2) is folded by the top and bottom folding unit (14,15).

• Further, cover patch cut piece (17) is pasted onto the top and bottom end (2A,2b) which are folded.

• The cover patch cut piece (17) is processed by cutting cover patch roll (18) into desired length by the patch welding unit (13) to form a bag (32) with block bottom ends.

• The bag (32) is further sent to stacker unit (31) for further storage.

The apparatus of the present invention therefore has a number of embodiments.

In the preferred embodiment, the present invention discloses an apparatus for manufacturing block bottom bags from sections of tubular film. The characterising features of the said apparatus are that the apparatus comprises the following stations: a thermoplastic film-roll feeding means (a) which consists of an unwinding unit (3) for unwinding the film role and an optionally a thermoplastic film edge guiding; a thermoplastic film preparatory means (b) that in itself consists of a preparatory means with an optional thermoplastic film perforation unit (5) or an optional index hole punching means (44), and a thermoplastic film cleaning means; an inspection and sensing means (c) consisting of an inspection unit (4); a thermoplastic film cut length cutting means (d) in the form of a high speed cross-cutter or an inclined cutter unit (7); a transportation means (e) which consisting of a traverse transfer unit (8) for transferring film from X to Y direction; a defect rejection means (f) to send the defective film cut pieces to ejection zone (40); a top and bottom edge opening means (g) that in itself consists of end opening unit (9) having a vertically positioned optional the edge opening means and an opening means have rotary mechanism; a valve patch application means (h) consisting of a valve patch unit (10) for storing, conveying and thermal welding of valve patch onto the one end of the film; a folding means (i) for top and bottom folding (14,15) of film; a cover patch application means (j) consisting of a cover patch unit (16) for storing, conveying and thermal welding of cover patch; a stacking means (k) consisting of a stacker unit (31) for storing the processed bag made of film; and a main automation and controlling means (m) consisting of controlling unit (41) for controlling the process of manufacture of bag (32) from film.

In a further embodiment, the unwinder unit (3) is either single station or multi station, wherein in the case of a multi-station unwinder unit there is provided a plurality of stations side by side having unique shaft (45) for each station for facilitating loading of multiple rolls. In another embodiment, the film perforation unit (5) is provided with at least one set of perforation roller (6) which comprises of plurality of needle shaped fins projecting outwards spread over the roller at a density of 80-90 needles per square centimetre in a cluster form.

In yet another embodiment, the diameter of the needles is in the range of 0.5mm to 0.7mm.

In still another embodiment, said inspection unit (4) comprises an emitter (42) and receiver units (43) capable of capturing the image of the thermoplastic film passing through it and detecting any defects or change in the colour of the said thermoplastic film or any crack or breaks is indicated by the emitter / receiver unit and defects are detected.

In yet further embodiment, said cutting means (d) comprises a cutting unit (7) that works on a cold cutting principle.

In a still further embodiment, the edge opening means (g) comprises of end opening unit (9) where the top and bottom ends (2A,2B) are opened using a rotary mechanism or a mechanism that operates in a vertical plane, and wherein the sides before subjecting to the rotary mechanism are opened by the suction means or any kind of means such as clipper arrangement which can open the two layers of film, and wherein the opened layers of film are subjected to the profiled structures which rotate such that during the movement in Y direction the bag is opened.

In another embodiment, the valve patch application means (h) comprises a valve patch unit (10) which in itself comprises a valve patch roll (12) which is mounted on a shaft (45) which is free to rotate such that the supply of the valve patch (36) is done continuously and smoothly, and a patch welding unit (13) which cuts the valve patch (36) into valve patch cut piece (11) of desired length and paste it over the bottom end of the cut piece of film (2).

In yet another embodiment, the patch welding unit (13) fixes said valve patch (11) with the cut piece (2) using means such as hot welding, hot melt gluing or by using ultrasonic methods.

In still another embodiment, the folding means (i) comprises a top folding unit (14) and a bottom folding unit (15) that make folds to form the bottoms of the block-bottom bags, and wherein said top and bottom folding units (14,15) are identical in construction and are placed at side A and side B respectively.

In a further embodiment, the cover patch application means (j) comprises a cover patch unit (16) which in itself comprises two cover patch rolls (18) that supply cover patches (37) to the bottom and top end of the folded cut piece of film (2) separately.

In yet further embodiment, the two cover patch rolls (18) are identical in construction and are mounted on a single frame.

In a still further embodiment, the cover patches (37) are cut into cover patch cut pieces (17) into desired length and pasted over the top and bottom of the cut piece of the film (2) using a patch welding unit (13).

In another embodiment, the patch welding unit (13) comprises a frame (19) on which first idler roller (20), a second idler roller (21), third idler roller (23) are mounted to provide tension to the patch which is unwounded from the rolls (12, 18); a pressure roller (23) is also mounted on the frame (19) to apply pressure on the patch (36/37) at first end (33); a hot drum (27), and a master cutter roller (24) is present at the second end (34) to cut the patches (36/37), wherein said master cutter roller (24) contains a set of blade or sharp knife, and wherein said hot drum (27) preheats the patch cut piece (11/17) so that in the later stages the patch can be pasted over the cut piece of film (2) with good adhesion.

In a further embodiment, a first sensor (25) is provided to sense the edge of the patch (36/37) such that any lateral displacement of the patch (36/37) can be corrected, and a second sensor (26) is provided to sense the print mark and said patch is cut at a predetermined length by sensing the print mark.

In yet another embodiment, a suction roller (28) is provided to suck the valve patch cut piece (11) or the cover patch cut piece (17) to convey these and lay them on said cut piece (2) wherein said suction cylinder (28) comprises of plurality of micro pores (38) through which suction is created, and a support or impression roller (29) is provided to provide a positive drive to the film (2).

In a still further embodiment, a hot gun (30) having a nozzle (39) is provided to throw a gust of air between the patch (11/17) and cut price of film (2) to create a heating zone the temperature of which is regulated by the amount of air to the thrown by the hot gun (30).

In a yet further embodiment, the temperature of the heating zone is kept just below the melting temperature of the film or more preferably plastic i.e., in the range of 80-100 °C or more preferably 95° such that film (2) and patch (11/17) does not melt but creates a good bonding, following which the block bottom bags are ready to be transported to stacking stations (31).

In another embodiment, all operations are controlled in synchronous manner using electronic control and automation system, and wherein the main control system has facility for input of required control and process parameters through human machine interface. In another embodiment, some of the stations are operated manually.

In another embodiment, a method of manufacturing of the block bottom bag from thermoplastic film using the apparatus disclosed in the foregoing embodiments. This method has the following characterising steps: a) unwinding a thermoplastic film roll (1) from the unwinder unit (3); b) passing the inspected film through a perforation unit (5) where nano preformation marks are made onto the film by the perforation roller (6); c) inspecting the perforated film in the inspection unit (4) thereby cutting the perforated film into cut piece (2) by cutting unit (7) such that top end (2A) and bottom end (2B) is created which are then opened; d) transferring the cut piece (2) from X direction to Y direction using the transfer unit (8); e) Opening of the film (2) at the end using the end opening unit (9); f) affixing the valve patch cut piece (11) onto the bottom end (2B); h) folding the top and bottom ends (2A, 2B) of the cut piece (2) using, respectively, the top and bottom folding units (14, 15); i) affixing the cover patch cut piece (17) onto the folded top and bottom ends (2A, 2B), thereby forming a bag (32) with block bottom ends.

In yet another preferred embodiment, the invention discloses a block bottom bag made from a tubular film, said bag having a parallelepipedal shaped bottom characterised in that said bag is wholly constructed of heat-sealable thermoplastic material with the bottom being formed and joined to the side walls of the bag by non-contact type thermal welding. 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.

Claims

Claims:

1. An apparatus for manufacturing block bottom bags from a tubular film, characterised in that said apparatus comprises of the following: a thermoplastic film-roll feeding means (a) which consists of an unwinding unit (3) for unwinding a roll of a tubular film and an optional a thermoplastic film edge guiding; a thermoplastic film preparatory means (b) consists of a preparatory means with an optional thermoplastic film perforation unit (5) or an optional index hole punching means, and a thermoplastic film cleaning means;(c) an inspection and sensing means (c) consisting of an inspection unit (4); a thermoplastic film cut length cutting means (d) in the form of a high speed cross-cutter or an inclined cutter unit (7); a transportation means (e) which consisting of a traverse transfer unit (8) for transferring film cut pieces from X to Y direction; a defect rejection means (f) to send the defective film cut pieces to ejection zone (40); a top and bottom edge opening means (g) consisting of end opening unit (9); a valve patch application means (h) consisting of a valve patch unit (10) for storing, conveying and thermal welding of valve patch onto the one end of the film cut pieces; a folding means (i) for top and bottom folding (14,15) of film cut pieces; a cover patch application means (j) consisting of a cover patch unit (16) for storing, conveying and thermal welding of cover patch; a stacking means (k) consisting of a stacker unit (31) for storing the processed bag made of film cut pieces; and a main automation and controlling means (m) consisting of controlling unit (41) for controlling the process of manufacture of bag (32) from film cut pieces.

2. The apparatus as claimed in claim 1, wherein said unwinder unit (3) is either single station or multi station, wherein in the case of a multistation unwinder unit there is provided a plurality of stations side by side having unique shaft for each station for facilitating loading of multiple rolls.

3. The apparatus as claimed in claims 1 and 2 wherein said film perforation unit(5) is provided with at least one set of perforation roller (6) which comprises of plurality of needle shaped fins projecting outwards spread over the roller at a density of 80-90 needles per square centimetre in a cluster form.

4. The apparatus as claimed in claim 3, wherein the diameter of the needles is preferably in the range of 0.5mm to 0.7mm.

5. The apparatus as claimed in claims 1 to 4, wherein said inspection unit (4) comprises an emitter (42) and receiver units (43) capable of capturing the image of the thermoplastic film passing through it and detecting any defects or change in the colour of the said thermoplastic film or any crack or breaks is indicated by the emitter / receiver unit.

6. The apparatus as claimed in claims 1 to 5, wherein said cutting means (d) consists of a cutting unit (7) that works on a cold cutting principle.

7. The apparatus as claimed in claims 1 to 6, wherein said edge opening means (g) consisting of end opening unit (9) where the top and bottom ends (2A,2B) are opened using a rotary mechanism or a mechanism that operates in a vertical plane, and wherein the sides before subjecting to the rotary mechanism are opened by the suction means or any kind of means such as clipper arrangement which can open the two layers of film, and wherein the opened layers of film are subjected to the profiled structures which rotate such that during the movement in Y direction the bag is opened.

8. The apparatus as claimed in claims 1 to 7, wherein said valve patch application means (h) comprises a valve patch unit (10) which further comprises a valve patch roll (12) mounted on a shaft which is free to rotate such that the supply of the valve patch (36) is done continuously and smoothly, and a patch welding unit (13) which cuts the valve patch (36) into valve patch cut piece (11) of desired length and paste it over the bottom end of the cut piece of film (2).

9. The apparatus as claimed in claim 8, wherein said patch welding unit (13) fixes said valve patch (11) with the cut piece (2) using means such as hot welding, hot melt gluing or by using ultrasonic methods.

10. The apparatus as claimed in claims 1 to 9, wherein said folding means (i) comprises a top folding unit (14) and a bottom folding unit (15) that make folds to form the bottoms of the block-bottom bags, and wherein said top and bottom folding units (14,15) are identical in construction and are placed at side A and side B respectively.

11. The apparatus as claimed in claims 1 to 10, wherein said cover patch application means (j) comprises a cover patch unit (16) which in itself comprises two cover patch rolls (18) that supply cover patches (37) to the bottom and top end of the folded cut piece of film (2) separately. The apparatus as claimed in claim 11, wherein said two cover patch rolls (18) are identical in construction and are mounted on a single frame. The apparatus as claimed in claim 12, wherein said cover patches (37) are cut into cover patch cut pieces (17) into desired length and pasted over the top and bottom of the cut piece of the film (2) using a patch welding unit (13). The apparatus as claimed in claim 13, wherein said patch welding unit (13) comprises a frame (19) on which first idler roller (20), a second idler roller (21), third idler roller (23) are mounted to provide tension to the patch which is unwounded from the rolls (12, 18); a pressure roller (23) is also mounted on the frame (19) to apply pressure on the patch (36/37) at first end (33); a hot drum (27), and a master cutter roller (24) is provided at the second end (34) to cut the patches (36/37), wherein said master cutter roller (24) contains a set of blade or sharp knife, and wherein said hot drum (27) preheats the patch cut piece (11/17) so that in the later stages the patch can be pasted over the cut piece of film (2) with good adhesion. The apparatus as claimed in claims 1 to 14, wherein a first sensor (25) is provided to sense the edge of the patch (36/37) and correct any lateral displacement of the patch (36/37). The apparatus as claimed in claims 1 to 15, a second sensor (26) is provided to sense any print marks existing on the film, and to cut the patch at a predetermined length by sensing said print mark. The apparatus as claimed in claim 14, a suction roller (28) is provided to suck the valve patch cut piece (11) or the cover patch cut piece (17) to convey these and lay them on said cut piece (2) wherein said suction cylinder (28) comprises of plurality of micro pores (38) through which suction is created, and a support or impression roller (29) is provided to provide a positive drive to the film (2). The apparatus as claimed in claim 17, wherein a hot gun (30) having a nozzle (39) is provided to throw a gust of air between the patch (11/17) and cut price of film (2) to create a heating zone, the temperature of which is regulated by the amount of air thrown by the hot gun (30). The apparatus as claimed in claim 18, wherein the temperature of the heating zone is kept just below the melting temperature of the film or more preferably plastic i.e. in the range of 80-100 °C or more preferably 95° such that film (2) and patch (11/17) does not melt but creates a good bonding. The apparatus as claimed in claims 1 to 19, wherein all operations are controlled in synchronous manner using electronic control and automation system, and the main control system has facility for input of required control and process parameters through human machine interface. The apparatus as claimed in claims 1 to 19 wherein, some of the stations may be operated manually. The apparatus as claimed in claims 1 to 21, wherein said end opening unit (9) has a vertically positioned edge opening means having a rotary mechanism. The apparatus as claimed in claims 1 to 22, wherein said preparatory means has a thermoplastic film perforation unit (5). The apparatus as claimed in claims 1 to 24, wherein said preparatory means has an index hole punching means, and a thermoplastic film cleaning means. The method of manufacturing of the block bottom bag from thermoplastic film using the apparatus as claimed in claims 1 to 24, characterised in that said method comprises the steps of a) unwinding a thermoplastic film roll (1) from the unwinder unit (3); b) passing the inspected film through a perforation unit (5) where nano preformation marks are made onto the film by the perforation roller (6); c) inspecting the perforated film in the inspection unit (4) thereby cutting the perforated film into cut piece (2) by cutting unit (7) such that top end (2A) and bottom end (2B) is created which are then opened; d) transferring the cut piece (2) from X direction to Y direction using the transfer unit (8); e) Opening of the film (2) at the end using the end opening unit (9); f) affixing the valve patch cut piece (11) onto the bottom end (2B); h) folding the top and bottom ends (2A, 2B) of the cut piece (2) using, respectively, the top and bottom folding units (14, 15); i) affixing the cover patch cut piece (17) onto the folded top and bottom ends (2A, 2B), thereby forming a bag (32) with block bottom ends. block bottom bag made from a tubular film, said bag having a parallelepipedal shaped bottom characterised in that said bag is wholly constructed of heat-sealable thermoplastic material with the bottom being formed and joined to the side walls of the bag by non-contact type thermal welding.