CN112739531B

CN112739531B - Method and device for producing a storage bag and storage bag

Info

Publication number: CN112739531B
Application number: CN201980061516.8A
Authority: CN
Inventors: 悉达尔斯·罗希亚
Original assignee: Lohia Corp Ltd
Current assignee: Lohia Corp Ltd
Priority date: 2018-09-23
Filing date: 2019-09-17
Publication date: 2023-06-09
Anticipated expiration: 2039-09-17
Also published as: TW202019779A; ZA202100871B; MX2021002493A; PE20210742A1; TWI764047B; WO2020058828A1; CN112739531A; BR112021004899A2

Abstract

A method for producing a storage bag with an integrally formed valve, the resulting bag and an apparatus for producing such a bag are disclosed. The method is characterized in that the valve (3) of the bag (2) is formed by folding the corner (13) of the tubular member (5) at the second open end (8) inwardly, followed by cutting off the edge band (22) of the tubular member (5) formed with the valve (3) and closing the second open end (8) by attaching a second sealing band (25) to the second open end (8). In another aspect of the invention, at least one hole (29) is formed in the side wall portion (9A and/or 9B) of the tubular member (5) to establish a connection between the second sealing band (25) and at least one side wall (19) of the valve (3). The resulting bag has a valve (3), the height (23) of which valve (3) is smaller than the depth (24) of the valve (3), and wherein a second sealing band (25) is attached to the second end (8) of the tubular member (5).

Description

Method and device for producing a storage bag and storage bag

Technical Field

The present invention relates generally to the field of bags for transporting, packaging and storing powdered or granular materials such as cement.

In particular, the invention relates to a method for producing bags with integrally formed valves, the resulting bags and a device for producing such bags.

Background

Bags or sacks have been used for packaging/storing/transporting materials such as grains, flours and various industrial materials. There are two main types of bags used: pillow type and box type. Box-type bags are manufactured using heat sealing techniques, however, their manufacturing process is capital intensive. The most common pillow bags are made by sewing one end of a tubular roll by properly folding the end to be sewn. Suturing is a simple and economical process, which can be performed either manually or automatically. However, stitching weakens the integrity and strength of the web as the needle pierces the web material. Some manufacturers use high strength materials to compensate for the loss of strength, however, it is not possible to achieve a complete seal of the filler material from the external environment. Stitching can also lead to theft of material, especially during shipping and handling of the bag. The folding required at the ends to be sewn also requires a greater length of web material, which is an economic disadvantage.

The problems of web perforation and resultant theft can be overcome by using heat sealing techniques such as heat bars or ultrasonic methods, however, these methods require precise handling control and also require high strength webs, without which there is a risk of bursting the filled bag and this reduces the weight limit of the package.

Another problem exists in bags having a fill valve provided for more reliably filling material than through the open end of the bag. However, the fill valve is typically not securely connected to the bag. Thus, there is a risk that the valve may be deployed or detached from the bag.

It is well known in the art to provide bags with self-closing valves, such as from AT512459A1, which allow for quick filling and self-closing of filled bags. The valve is formed in a flattened state of the bag by means of a folding device. These bags are typically filled by means of a filling device such as a filling tube. For this purpose, the valve is unfolded and the filling device is inserted into the valve. After withdrawal of the filling device from the bag, the valve is closed due to the internal pressure of the powdered or granular material filled into the bag. In this prior art, the open end of the bag with the valve is closed by folding the top edge and subsequent sewing. However, this weakens the material and can lead to bag breakage. Furthermore, the filling material may leak through the seam, which is particularly a concern when cement is filled into the bag.

Accordingly, it is an object of the present invention to obviate or at least mitigate at least the individual disadvantages of the prior art.

There is therefore a need for a bag/sack and a method of producing the same that overcomes these drawbacks, whereby the integrity and strength of the web material is not unduly impaired, and wherein the seal is strong and integral and has a firmly placed valve.

In particular, it is an object of the present invention to provide a bag with an integrally formed valve which reliably closes the filled bag when the filling device is withdrawn from the valve, prevents leakage of filling material, and is particularly durable. Furthermore, it is an object of the present invention to provide a method and an apparatus for producing such bags.

Disclosure of Invention

The present invention provides a method for producing a bag with a valve. The bag may be made from a web material, which may be a woven fabric, a nonwoven fabric, or a composite thereof, optionally coated or laminated. Preferably a woven polyolefin or a woven polypropylene material. For purposes of this description, the terms web, web material, or fabric are used synonymously.

Accordingly, the method comprises the steps of:

a) Providing a tubular member made of a fabric, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material, having a first open end and a second open end, each open end having a respective circumferential edge;

b) Closing the first open end of the tubular member, preferably by attaching a first sealing strip to the first open end of the tubular member;

c) A valve forming a bag by folding the corner of the tubular member at the second open end inwardly into the interior of the tubular member;

d) Cutting off a lower edge band of the tubular member having the valve formed at the second open end of the tubular member; and

e) The second open end is closed by attaching a second sealing strip to the second open end.

A fabric pouch with a valve is also provided. The bag may be produced from a web material, which may be a woven fabric, a nonwoven fabric, both optionally coated and laminated. The sealing strip may be made of a woven or nonwoven material, preferably coated or laminated, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material, optionally the sealing strip may have pre-applied on its surface an adhesive attaching itself to the bag. This means that the supplied tape is ready with adhesive applied.

Accordingly, the bag of the present invention comprises:

-a tubular member made of a fabric, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material, having a closed first end, preferably by means of a first sealing band;

-a valve formed by folding a corner of the second end of the tubular member inwardly into the interior of the tubular member, the valve having a height less than the depth of the valve; and

-a second sealing band attached to the second end of the tubular member.

In another aspect, the present invention provides an apparatus for producing bags having at least one valve. The apparatus is capable of producing bags made from a web material, which may be a woven fabric, a nonwoven fabric, both optionally coated or laminated.

Accordingly, the apparatus disclosed herein comprises:

a) A supply unit for providing a tubular member made of a fabric, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material, having a first open end and a second open end, each open end having a respective circumferential edge;

b) A first closing unit for closing the first open end of the tubular element, in particular by means of a first sealing band;

c) A valve forming unit for forming a valve of the bag by folding a corner of the second open end inwardly into the interior of the tubular member;

d) A cutting unit for cutting off the lower edge strip of the second open end;

e) And a second closing unit for closing the second open end by means of a second sealing tape.

All aspects of the invention relate to each other and any embodiment described for one aspect correspondingly relates to all other aspects and embodiments mentioned. In particular, the advantages and features mentioned in the context of the method also relate to the device and the bag.

Drawings

Fig. 1 shows an apparatus for producing bags with a firm valve.

Fig. 1A and 1B show schematic views of forming a fold for making a valve.

Fig. 2 shows a welding unit for connecting at least one side wall of a valve to an adjacent side wall portion of a tubular member by means of a welding process.

Fig. 3 shows an alternative device for producing bags with a firm valve.

Fig. 4 shows the connection of the side wall of the valve to the adjacent side wall portion by means of a single welding unit.

Fig. 5 shows a side view of the punching unit.

Parts list:

1. device and method for controlling the same

2. Bag(s)

3. Valve

4. Coiled material/fabric coil

5. Tubular member

6. Circumferential side wall

7. First open end 7A-circumferential edge of first open end

8. Second open end 8A-circumferential edge of second open end

9A/9B, sidewall portions

10. First sealing tape

11. Tape roll of first sealing tape

12. Edges of the first open end

13. Corner portion

14. Triangle-shaped

15. A first side or a first right-angle side

16. Longitudinal axis of tubular member

17. A second side or a second right angle side

18. Bevel edge

19. Side wall of valve

20. Separating element

21. Separating layer

22. Lower edge belt

23. Height of (1)

24. Depth of

25. Second sealing tape

26. Coil of second sealing tape

27. Edges of the second open end

28. Bonding or sealing devices

29. Hole(s)

30. Bolt

31. Support element

101. Supply unit for tubular members

102. A first closing unit for the first open end

103. Valve forming unit

104. Cutting unit

105. A second closing unit for the second open end

106. Welding unit

107. Valve connection unit

108. Stamping unit

109. Sealing tape cutting unit

Detailed Description

The present invention provides a method for producing a bag with a valve, comprising the steps of:

a) Providing a tubular member made of a fabric, in particular a polymeric material, preferably a polyolefin or a woven polypropylene material, having a first open end and a second open end, each open end having a respective circumferential edge;

c) Forming a valve of the bag by folding the corner of the tubular member at the second open end inwardly into the interior of the tubular member;

e) The second open end is closed by attaching a second sealing band to the second open end and securing the valve.

The bag may be made from a web material, which may be a woven, nonwoven fabric, optionally coated or laminated. Preferably a woven polyolefin or a woven polypropylene material.

By performing steps a) to e) of the method, preferably but not necessarily sequentially, a particularly durable bag with an integrated self-closing valve is obtained, wherein the valve reliably closes the filled bag once the filling device is withdrawn from the bag. The valve is closed by the pressure exerted by the filling material. The filling material, in particular a powdery or granular material such as cement, is reliably prevented from leaking from the bottom end of the bag. The valve is thus formed by the tubular member itself and thus forms an integral part of the bag. In other words, the bag comprising the valve is manufactured in one piece, i.e. as a tubular piece.

The type of bag produced, such as pillow or gusset, is defined by the form of the tubular member used in the manufacturing process. Thus, depending on the type of bag produced, the tubular member may have folds. The method of the invention and the device of the invention can be used for producing two types of bags.

The tubular member may be made of a synthetic woven fabric, in particular a polymeric material, preferably a polyolefin or polypropylene material. The fabric may be composed of ribbons or strips typically having a width of up to 10 mm and a thickness of 15 to 120 microns. The fabric may be coated or may be uncoated. The tubular member has a circumferential side wall that is preferably free of openings or holes except for a first open end and a second open end. The sidewall may comprise several sidewall portions. Typically, each sidewall portion defines one side of the bag being produced. Due to the flexibility of the material used, the tubular member is preferably substantially flat during the manufacturing process of the bag. In this case, the side wall may be divided into at least two parts, namely a top wall part and a lower side wall part, which are joined to each other at the side edges of the flat tubular member. The first open end of the tubular member is opposite the second open end. At the beginning of the method in step a), the first open end and the second open end preferably have substantially the same dimensions.

In step a), the tubular member is provided, i.e. physically placed and ready for subsequent steps. The step of providing the tubular member may comprise manufacturing the tubular member. For example, the tubular member may be woven, or cut from a (coil) roll or any other supply device having a continuous tubular member, in particular a woven fabric. Alternatively, the manufacturing may also be performed independently of and before step a). In this case, the tubular member can be simply taken out of the stack having many tubular members.

In step b), the first open end of the tubular member is closed. To close the first open end, a variety of closing techniques may be applied. For example, the first open end may be closed by stitching or adhesive. Preferably, however, the first open end is closed by means of a first sealing strip attached to the edge of the opposite side wall portion at the first open end. The first sealing strip may be removed from the stack with the sealing strips or may be cut from a continuous sealing strip. If the first sealing strip is cut from a continuous sealing strip, the cutting may be performed before or after the first sealing strip is attached to the first open end. The first sealing band preferably has two band portions connected to each other, one at each side wall portion of the tubular member. In particular, the cross section of the first sealing strip forms a V-shape or a U-shape. The first sealing band may be glued or welded to the tubular member, preferably by means of hot air welding or thermal welding. The thermal welding technique may use laser techniques, ultrasonic techniques, or any other high frequency technique. The two strap portions, i.e. the sides of the U-shaped or V-shaped cross section, are thereby attached to the edge of the first open end. Alternatively or additionally, the first sealing band at the first open end may be stitched to the tubular member, as the load at the stitching may be less at the first (upper) open end than at the second (lower) open end.

The first sealing tape may be made of a woven or nonwoven material, preferably coated or laminated, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material, optionally with pre-applied adhesive.

In step c), the valve is formed by folding the corner of the second open end, which is still open at this stage, inwards into the interior of the tubular member. Because the tubular member is generally flat due to its flexibility, it is advantageous to lift one edge of the second open end to facilitate folding of the corners. The resulting valve has two opposing side walls so that the filling device can be received therebetween. In step c), the height and depth of the folded valve are substantially the same. The height of the valve extends to a direction parallel to a longitudinal axis of the tubular member extending from the first open end to the second open end. The depth extends in a direction perpendicular to the longitudinal axis of the tubular member.

In step d), the (lower) edge band of the tubular member, which is formed with the valve at the second open end of the tubular member, is cut off, in particular by means of a knife. The cutting portion is preferably a straight cutting portion without any curved portion. As a result of the cutting, the lower end of the valve is truncated. The resulting valve thus has a height in its final state which is shorter than its depth. In other words: the height of the valve reduces the width of the lower edge strip cut away after the corner is folded. This improves the reliability of the self-closing mechanism of the valve in the final bag, as the valve is prevented from being accidentally folded to the outside in response to material filling. The width of the lower edge strip is at least 10 mm, preferably at least 70 mm, preferably less than 150 mm. After cutting off the lower edge strip, the tubular member has a final length (i.e. an extension in the direction of the longitudinal axis) of the bag to be produced.

In step e), the second open end of the tubular member is closed by attaching a second sealing band to the second open end of the tubular member, except for the valve. The valve is not obstructed by the attachment of the second sealing strip. Corresponding to the attachment of the first sealing tape, the second sealing tape may be taken out of the stack with sealing tapes or may be cut from a continuous sealing tape, in particular from a roll. If the second sealing strip is cut from a continuous sealing strip, the cutting may be performed before or after the second sealing strip is attached to the second open end. The second sealing band preferably has two band portions connected to each other, one at each side wall portion of the tubular member. In particular, the cross section of the second sealing strip forms a V-shape or a U-shape. The second sealing band may be glued or welded to the tubular member. The two strap portions, i.e. the sides of the U-shaped or V-shaped cross section, are thereby attached to the edge of the second open end. Alternatively or additionally, a second sealing band at the second open end may be stitched to the tubular member.

The second sealing tape may be made of a woven or nonwoven material, preferably coated or laminated, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material, optionally with pre-applied adhesive.

As a key aspect of the invention, the valve formed is so strong that it does not unfold when filling is completed or in any other case. The simplest way to achieve this is to firmly attach at least one valve wall to the second sealing strip. In a preferred method of securing the valve, at least one hole is formed in at least one adjacent sidewall portion to establish a secure connection between the second sealing band and at least one sidewall of the valve in step e). When the second sealing band is attached to the second open end in step e), at least one side wall of the valve is connected to the second sealing band by at least one hole, for example by gluing or welding, preferably hot air welding or thermal welding. The second sealing band may be glued or welded to the tubular member, preferably by means of hot air welding or thermal welding. The thermal welding technique may use laser techniques, ultrasonic techniques, or any other high frequency technique. Since the second sealing band is also connected to an adjacent side wall of the tubular member, at least one side wall of the valve is connected to an adjacent side wall portion via the second sealing band. The at least one aperture is preferably positioned proximate to the second open end such that it may be completely covered by the second sealing strip.

Preferably, the first sealing band and/or the second sealing band is attached to the tubular member by means of welding (preferably by hot air welding or ultrasonic welding) or bonding.

The position of the at least one aperture may be predetermined based on the size of the bag and valve. Thus, once the position of the cut made by the tubular web for making the tubular member 5 is known, the action of forming at least one hole can also be performed at virtually any time during the method (i.e. even before any of steps b, c, d and e).

After performing step e), the second sealing strip may be cut to conform to the width of the (now closed) second open end without a valve. In this way, the second sealing strip does not protrude into the valve portion.

As shown in fig. 1A and 1B, in a preferred embodiment, the inwardly folded corners of the second open end for forming the valve have a triangular shape, in particular an isosceles triangle. In this embodiment, the first side (first right angle side) of the triangle is oriented substantially in a direction perpendicular to the longitudinal axis of the tubular member and the second side (second right angle side) is oriented substantially in a direction parallel to the longitudinal axis of the tubular member. As shown in fig. 1A, the first side of the triangle is a portion of the folded side of the flat tubular member prior to folding the side wall up to form a fold. Similarly, the second side edge is a portion of the opening edge of the second open end prior to forming the fold. The beveled edge connects the sidewall and the second open end.

According to one embodiment of the invention, step d) may comprise cutting off the lower edge band substantially at right angles to the longitudinal axis of the tubular member and along the entire width of the second open end of the tubular member in which the valve is formed. The longitudinal axis thus extends from the first open end to the second open end of the tubular member.

As an alternative to fixing the valve so that it does not undesirably open or fold outwards (i.e. contrary to the previously described inward folding), after forming the valve according to step c), at least one side wall of the valve, preferably the bottom edge of the side wall of the valve, is firmly connected to the adjacent side wall portion of the tubular member. Preferably, the two side walls of the valve are each connected to the adjacent side wall portions of the tubular member.

A quick and reliable connection of the side walls of the valve can be achieved if at least one side wall portion of the valve is connected to an adjacent side wall of the tubular member by means of a process which applies a hot melt adhesive for connection purposes. Alternatively, any welding process may be used for this purpose, with which the fabric may be partially melted and at least one side wall of the valve may be connected to an adjacent side wall portion of the tubular member without using any connecting material such as glue. Also, preferably, both side walls of the valve are connected to respective adjacent side wall portions of the tubular member. To this end, both side walls of the valve may be connected to respective adjacent side walls of the tubular member at the same time. Alternatively, the side walls may be connected to their adjacent side wall portions one after the other, i.e. in different welding processes.

In order to avoid interconnecting the valve side walls during welding, a separating element, in particular a separating layer preferably made of steel, may be used during welding to temporarily space the valve side walls from each other. The advantage of the separate elements is that the side walls of the valve are not welded to each other during the welding process.

Alternatively, the welding may be performed using an ultrasonic welding process.

In a further embodiment, two methods of securing the valve are implemented, namely methods involving forming at least one hole in at least one adjacent sidewall portion, through which hole the second side band is firmly connected to one sidewall of the valve; and at least one side wall of the valve, preferably the bottom edge of the side wall of the valve, is firmly connected to the adjacent side wall portion of the tubular member.

The present invention further provides a fabric pouch comprising:

-a tubular member made of, in particular, a woven fabric, having a closed first end, preferably by means of a first sealing band;

-a valve formed by folding the corner of the tubular member at the second end inwards into the interior of the tubular member, the valve having a height less than the depth of the valve;

-a second sealing band attached to the second end of the tubular member.

The bag may be obtained by the method of the invention. Advantageously, the height of the valve of the bag is shorter than its depth. The height of the valve extends in a direction parallel to a longitudinal axis of the tubular member extending from the first open end to the second open end. The depth extends in a direction perpendicular to the longitudinal axis of the tubular member. The longitudinal axis extends from the first open end to the second open end. The length of the bag is preferably between 200mm and 1400mm, more preferably between 350mm and 950 mm. The width of the bag is preferably between 170mm and 850mm, more preferably between 270mm and 620 mm.

To prevent the valve of the bag from being undesirably deployed, at least one side wall of the valve may be connected to an adjacent side wall portion of the tubular member.

The invention also provides an apparatus for producing bags having at least one valve, comprising:

a) A supply unit for providing a tubular member, in particular made of a woven fabric, preferably polypropylene, having a first open end and a second open end, and each open end having a respective circumferential edge;

d) A cutting unit for cutting off the lower edge strip of the second open end;

The apparatus of the present invention is capable of performing the above-described method. Preferably, the units are arranged sequentially from a) to e). The supply unit may comprise a roll with a coiled continuous tubular member from which the tubular member may be cut, for example by cold cutting, hot cutting, ultrasonic cutting or laser cutting. Alternatively, the supply unit may comprise a stack from which the tubular members may be taken out one after the other. The first closing unit may comprise a supply of sealing tape, in particular V-shaped or U-shaped tape. The sealing tape may be removed from the stack or may be cut from the roll. For cutting, the first closing unit may comprise a knife. Alternatively, the first closed cell may use cold cutting, hot cutting, ultrasonic cutting or laser cutting. The valve forming unit may comprise a folding member which folds, i.e. squeezes or transfers, the corners of the tubular to the interior of the tubular. Advantageously, the valve forming unit may further comprise a lifting member lifting an edge of the second open end of the tubular to facilitate folding of the corner. The cutting unit may include a knife. The second closed cell may be constructed similar to the first closed cell. For attaching the first sealing band and/or the second sealing band to the tubular member, the first closing unit and/or the second closing unit may use welding (preferably hot air welding, ultrasonic welding) or bonding.

In a first embodiment of the device, the first and/or the second closing unit has a welding device for connecting the first/second sealing band to the first/second open end of the tubular member. The welding device, preferably a thermal welding device, may heat and partially melt the first sealing band/second sealing band and/or the first open end/second open end, thereby forming an integral connection of the first sealing band/second sealing band and the tubular member. The welding device may also be an ultrasonic welding device.

Further, the device may comprise an adhesive unit for connecting at least one side wall of the valve to an adjacent side wall portion of the tubular member by means of glue.

In a preferred embodiment, the device further comprises a punching unit for punching at least one hole in at least one side wall portion of the tubular member before closing the second open end by means of the second sealing strip, wherein the hole is punched close to the second open end such that a connection is established between the second sealing strip and the at least one side wall of the valve when the second sealing strip is attached.

In another embodiment, the device comprises a welding unit for connecting at least one side wall of the valve to an adjacent side wall portion of the tubular member by means of a welding process, preferably a thermal welding process. However, the process may also be an ultrasonic welding process.

In order to avoid connecting the side walls of the valve during welding, the welding unit may comprise a separating element, in particular a separating layer preferably made of metal, which may be inserted between the side walls of the valve during welding.

In a further embodiment, the device comprises the aforementioned punching unit provided for the same purpose in the preferred embodiment and a welding unit for connecting at least one side wall of the valve to an adjacent side wall portion of the tubular member by means of a welding process.

Hereinafter, preferred embodiments of the present invention will be described with the aid of the accompanying drawings.

Fig. 1 schematically shows an apparatus 1, here a production line, for producing bags 2 with integrated valves 3. The production line has several work stations (left to right) for producing bags. The order shown in fig. 1 is only a preferred embodiment and the individual steps may be interchanged or combined as long as the result remains substantially the same. Each step performed may be implemented by a dedicated unit of the apparatus 1. Since these units are known per se, these units are only schematically shown in the figures.

Fig. 1 also shows a coil of web material 4 from which the tubular member 5 is cut by means of a cutting device such as a knife or laser cutter (not shown). Each tubular member 5 generally has a circumferential side wall 6 extending in the direction of the longitudinal axis of the tubular member, preferably without openings or holes except for a first open end 7 and a second open end 8 at opposite ends of the tubular member 5. Each open end 7 and 8 has a respective circumferential edge 7A and 8A. The tubular member 5 is made of a woven fabric, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material. Because of their flexibility, the tubular members 5 are substantially flat during the manufacturing process as shown. In this flattened condition, at least two opposite

side wall portions

9A and 9B of the tubular member 5 are formed with folded-up side edges 6A and 6B formed therebetween. In fig. 1, only the top side wall portion 9A is visible when the tubular member 5 is shown in top view.

Alternatively, instead of cutting, the tubular 5 may of course simply be taken out of the stack or from another production line for producing the tubular 5. The step of cutting or simply removing the tubular member 5 may be generally referred to as a step of providing the tubular member or simply step a). This step may be implemented by the supply unit 101.

In a subsequent step, which may be referred to as step b) and which may be carried out by the first closing unit 102, the first open end 7 of the tubular member 5 is completely closed such that the material filled into the bag 2 cannot leave this side of the bag 2. Preferably, this is done by attaching a first sealing strip 10 to the first open end 7. To this end, the first sealing strip 10 may be cut from a continuous roll 11 of tape, or alternatively removed from the stack. The length of the first sealing strip 10 may be greater than the width of the first open end 7. There are a number of ways to attach or bond the first sealing strip 10 to the first open end 7. However, welding or bonding is preferred. For this purpose, it is preferred to bond or seal the device 28, in particular a device using glue/adhesive (natural or synthetic) bonding, or a device using a welding technique such as laser welding, ultrasonic welding or any other high frequency welding, or a hot air welding device. Such a bonding or sealing device 28 may be included in the first closed cell 102.

The first sealing band 10 preferably has two band portions (not shown) connected to each other, one for each side wall portion 9A (top side) and 9B (bottom side) of the tubular member 5. In particular, the cross section of the first sealing strip 10 forms a V-shape or a U-shape. The two band portions of the first sealing band 10, i.e. the sides of the U-or V-shaped cross section, are thereby attached to the edge 12 of the first open end 7. Alternatively or additionally, the first sealing band 10 at the first open end 7 may be stitched to the tubular member 5, as the load at the stitching may be less at the first (upper) open end 7 than at the second (lower) open end 8.

Subsequently, in a step c) carried out by a unit commonly referred to as valve forming unit 103, the valve 3 is formed into the tubular member 5. For this purpose, the corner 13 at the second open end 8 is folded inwards into the interior of the tubular member 5. As can be seen from fig. 1, the corner 13 is formed as two isosceles triangles 14 when folded inwards, which have a common edge or rim between them, the common edge being a first side edge 15 (first right-angle edge). The first side 15 of the triangle 14 is thus formed by a portion of the side edge 6A and is oriented substantially in a direction perpendicular to the longitudinal axis 16 of the tubular member 5. Similarly, the second side (second right angle side) 17 of each triangle 14 is formed by a portion of the circumferential edge 8A when folded inwardly. The second side 17 of each triangle 15 is oriented substantially in a direction parallel to the longitudinal axis 16 of the tubular member 5. Finally, the hypotenuse 18 of the triangle 14 is formed by folding up the

side walls

9A and 9B.

Obviously, the whole of the valve 3, eventually formed with the rest of the bag, comes from the fact that:

the first side 15 of the triangle 14 is an integral part of the folded-up side edge 6A;

the second side 17 of the triangle 14 is an integral part of the circumferential edge 8A; and is also provided with

The sloping edges 18 are an integral part of the

side walls

9A and 9B.

Although the valve 3 has an integrity with the bag in the manner explained herein, in order to prevent the valve from being undesirably unfolded outwards (i.e. contrary to the previously described inward folding), the device of the present invention is provided with a punching unit 108.

After cutting the tubular member 5 from the web roll 4, at least one hole 29 is formed in at least one adjacent

side wall portion

9A and 9B by means of a stamping unit 108 (see fig. 3) in order to establish a connection between the second sealing band 25 and at least one side wall 19 of the valve 3 in step e). In the embodiment shown, two holes 29 are punched. The two holes 29 may be in the

same wall portion

9A or 9B, or they may be in

different wall portions

9A or 9B. The holes 29 may be placed in any configuration with respect to each other as long as the second sealing strip 25 covers the at least one hole 29 when in its final position. The punching of the holes 29 must be carried out before or at the beginning of step e). The punching unit 108 can thus be placed anywhere in the device 1 as long as the hole 29 is punched before step e) or at the beginning of step e). The holes 29 may be through holes through the two

side wall portions

9A and 9B of the tubular member 5 and the two side walls 19 of the valve 3. Alternatively, it is sufficient if the hole 29 passes through only one of the respective adjacent

side wall portions

9A and 9B of the tubular member 5. In step e), the second sealing band 25 is finally attached to the second open end 8 using a bonding or sealing device 28, which may be part of the second closing unit 105. Welding or bonding is preferred, however, ultrasonic welding may also be used.

As a result of the attachment of the second sealing band 25 to the second open end 8, the side wall 19 of the valve 3 is connected to the second sealing band 25 through the hole 29. Since the second sealing band 25 is also connected to the

respective sidewall portion

9A or 9B at the second open end 8 of the tubular member 5, the sidewall 19 of the valve 3 is connected to the

adjacent sidewall portion

9A or 9B via the second sealing band 25. The aperture 29 is positioned close to the second open end 8 such that it can be completely covered by the second sealing strip 25.

Fig. 5 shows a side view of the punching unit 108. The punching unit 108 comprises a slidable bolt 30 punching at least one hole 29, preferably two holes 29, through the side wall portion 9 and the side wall 19 of the valve 3. The support element 31 supports the tubular member 5 and receives the bolt 30.

The position of the aperture 29 may be predetermined based on the size of the bag and valve. Thus, once the position of the cut made by the tubular member 5 made from the tubular web is known, the action of forming the holes 29 can also be performed at virtually any time during the method (i.e. even before any of steps b, c, d and e).

As an alternative to fixing the valve using the holes 29, at least one side wall 19 of the valve 3, preferably the edge of at least one side wall 19 of the valve 3 near the second open end 8, is firmly connected to the respective adjacent

side wall portions

9A and 9B of the tubular member 5. This step may be performed by a unit commonly referred to as a valve connection unit 107 (see fig. 3). Preferably, both side walls 19 of the valve 3 are connected to respective adjacent

side wall portions

9A or 9B of the tubular member 5. In the flattened state of the tubular member 5, the

side wall portions

9A and 9B are opposed to each other (see fig. 2 or 5).

A quick and reliable connection of the side wall 19 of the valve 3 can be achieved if the side wall 19 of the valve 3 is connected to the respective adjacent

side wall portions

9A and 9B of the tubular member 5 by means of a welding process, in particular an ultrasonic welding process performed by a welding unit 106. This is shown in more detail in fig. 2. By means of the welding process, the tubular member 5 and the fabric of the valve 3 formed in the tubular member 5 are partially melted and the wall 19 of the valve 3 is connected to the respective adjacent

side wall portions

9A and 9B of the tubular member 5 without using any adhesive material, such as glue.

As already described, preferably both side walls 19 of the valve 3 are connected to respective adjacent

side wall portions

9A or 9B of the tubular member 5. For this purpose, a separate welding process performed by a separate welding unit 106 may be used. The welding units 106 may be activated simultaneously or sequentially. As shown in fig. 1, the welding unit 106 may be integrated into the valve connection unit 107.

In order to avoid connecting the side walls 19 of the valve 3 to each other, a separating element 20, in particular a separating layer 21, preferably made of steel, may be used during welding to temporarily space the side walls 19 of the valve 3 from each other. The advantage of the separating element 20 is that the side walls 19 of the valve 3 are not welded to one another unexpectedly during the welding process.

Instead of welding, the side wall 19 of the valve 3 may be connected to the respective adjacent

side wall portion

9A or 9B of the tubular member 5 by means of a glue material, which may be a natural or synthetic adhesive, preferably a hot melt adhesive. This step may be implemented by an adhesive unit, which may be integrated into the valve connection unit 107.

In a further embodiment, the device comprises the aforementioned punching unit 108, which in a preferred embodiment is provided for the same purpose, and a welding unit 106 for connecting at least one side wall of the valve to an adjacent side wall portion of the tubular member by means of a welding process.

In step d), which may be carried out by the severing unit 104 and which may follow the valve forming unit 103 or the valve connecting unit 107, the lower edge strip 22 of the tubular member 3, with the valve 3 formed at the second open end 8 of the tubular member, is cut off, for example by means of a knife or another cutting device (not shown). The cut is preferably straight without any curvature. As a result, the resulting valve 3 has a height 23 in its final state that is shorter than its depth 24. In other words: the height 23 of the valve 3 reduces the width of the lower edge strip 22 that is cut away. The height 23 of the valve 3 extends in a direction parallel to the longitudinal axis 16 of the tubular member 5, the longitudinal axis 16 of the tubular member 5 extending from the first open end 7 to the second open end 8. The depth 24 extends in a direction perpendicular to the longitudinal axis 16 of the tubular member 5. This improves the reliability of the self-closing mechanism of the valve 3 in the final bag 2, as the valve 3 is prevented from being accidentally folded to the outside in response to filling of material. The cutting off of the lower edge band 22 may be performed substantially at right angles to the longitudinal axis 16 of the tubular member 5 and along the entire width of the second open end 8 where the valve 3 is formed.

After cutting off the lower edge strip 22, the second open end 8 is closed by attaching a second sealing strip 25 thereto in a step which may be referred to as step e). This step may be performed by a second closed cell 105, which may be similar to the first closed cell 102. In this regard, "closed" means that the second open end 8 is closed after removal of the lower edge band 22, but the valve 3 is left open. In other words: the second open end 8 is closed but the valve 3 is still open to receive material. Likewise, the second sealing strip 25 may be removed from the stack or, as shown, cut from a continuous roll 26 of tape. Similar to the first sealing band 10, the second sealing band 25 preferably has two band portions connected to each other, one for each

side wall portion

9A and 9B of the tubular member 5. In particular, the cross section of the second sealing strip 25 forms a V-shape or a U-shape. Two band portions of the second sealing band 25, i.e. the sides of the U-or V-shaped cross section, are thereby attached to the edge 27 of the second open end 8. Alternatively or additionally, the second sealing band 25 at the second open end 8 may be stitched to the tubular member 5. The second sealing band 25 may be glued or preferably welded to the tubular member 5. For this purpose, a further joining or sealing device 28 may be included in the second closing unit 105.

Since the second sealing band 25 may be too long and protrude from the bag 2 due to the presence of the valve 3, a sealing band cutting unit 109 may be placed at the end of the device 1. The unit 109 may cut away the portion of the second sealing strip 25 protruding above the valve 3.

The above-described process carried out with the device 1 results in a bag 2 having a closed first end (corresponding to the previous first open end 7) and a second end 8 formed with a valve 3. The second end 33 corresponds to the second open end 8 closed by means of the second sealing band 25.

Preferably, the

units

101, 102, 103, 104 and 105 shown in the figures are arranged in the production line in the order of 101, 102, 103, 104 and 105.

The advantages of bags made using the methods and apparatus disclosed herein are apparent.

While the above description contains many specifics, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of preferred embodiments thereof. It must be appreciated that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the present invention. Thus, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

Claims

1. A method for manufacturing a bag (2) with a valve (3), comprising the steps of: -providing a tubular member (5), said tubular member (5) being made of a fabric and having a first open end (7) and a second open end (8); -closing the first open end (7) of the tubular member (5) by attaching a first sealing tape (10) to the first open end (7) of the tubular member (5), characterized in that these steps are followed by the steps of:

a. -forming the valve (3) of the bag (2) by folding the corner (13) of the tubular member (5) at the second open end (8) inwardly into the interior of the tubular member (5);

b. -cutting off an edge band (22) of the tubular member (5) with the valve (3) formed at the second open end (8) of the tubular member (5); and

c. closing the second open end (8) by attaching a second sealing tape (25) to the second open end (8);

wherein prior to step c) at least one hole (29) is formed in the adjacent side wall portion (9A and/or 9B) to establish a connection between the second sealing band (25) and at least one side wall (19) of the valve (3) in step c).

2. A method as claimed in claim 1, wherein the tubular member (5) is made of a polymeric material.

3. A method as claimed in claim 1, wherein the tubular member (5) is made of a woven polyolefin or a woven polypropylene material.

4. A method as claimed in claim 1, wherein the inwardly folded corner (13) of the second open end (8) for forming the valve (3) has the shape of a triangle (14).

5. The method according to any one of claims 1 to 4, wherein step b) comprises cutting off the edge strip (22) substantially at right angles to the longitudinal axis (16) of the tubular member (5) and along the entire width of the second open end (8) of the tubular member (5) in which the valve (3) is formed.

6. A method according to any one of claims 1 to 4, wherein after forming the valve (3) according to step a), at least one side wall (19) of the valve (3) is connected to an adjacent side wall portion (9A or 9B) of the tubular member (5).

7. A method as claimed in claim 6, wherein after forming the valve (3) according to step a), a side edge of the side wall (19) of the valve (3) is connected to an adjacent side wall portion (9A or 9B) of the tubular member (5).

8. A method as claimed in claim 6, wherein said at least one side wall (19) of said valve (3) is connected to a respective adjacent side wall portion (9A or 9B) of said tubular member (5) by means of a welding process.

9. The method of claim 8, wherein the welding process is an ultrasonic welding process.

10. Method according to claim 8, wherein during the welding process a separating element (20) is used to temporarily space the side walls (19) of the valve (3) from each other.

11. The method of claim 10, wherein the separating element (20) is a separating layer (21) made of metal.

12. A method as claimed in claim 6, wherein said at least one side wall (19) of said valve (3) is connected to a respective adjacent side wall portion (9A or 9B) of said tubular member (5) by means of a glue material.

13. The method of claim 12, wherein the glue material is a hot melt adhesive.

14. The method according to any one of claims 1 to 4, wherein the first sealing band (10) and/or the second sealing band (25) are attached to the tubular member (5) by means of welding or bonding using an adhesive.

15. The method of claim 14, wherein the welding is hot air welding or ultrasonic welding.

16. The method of claim 6, wherein the number of holes (29) is two or more, and the holes (29) are arranged in any relative configuration with respect to each other.

17. The method of claim 6, wherein the second sealing strip covers at least one of the holes (29) after closing the second open end (8).

18. The method of any one of claims 1 to 4, wherein the first and second sealing bands are in the form of a U-shaped or V-shaped cross-section.

19. The method according to any one of claims 1 to 4, wherein the first sealing band (10) and/or the second sealing band (25) are made of a woven or nonwoven material.

20. The method of claim 19, wherein the first sealing band (10) and/or the second sealing band (25) are made of a polymeric material.

21. The method of claim 19, wherein the first sealing tape (10) and/or the second sealing tape (25) are made of a coated or laminated woven polyolefin or woven polypropylene material.

22. The method of any one of claims 1 to 4, wherein the first and second sealing strips have pre-applied on their surfaces an adhesive that attaches themselves to the bag.

23. A bag (2) made of a textile material, characterized in that it comprises:

-a tubular member (5) made of fabric, said tubular member (5) having a first end (32) closed by means of a first sealing band (10);

-a valve (3) formed by folding a corner (13) at the second end (8) of the tubular member (5) inwardly into the interior of the tubular member (5), the height (23) of the valve (3) being less than the depth (24) of the valve (3);

-a second sealing band (25) attached to the second end (8) of the tubular member (5);

wherein the side wall portion (9A or 9B) of the tubular member (5) has at least one hole (29) formed therein, the at least one hole (29) being covered by the second sealing tape (25), and

wherein at least one side wall (19) of the valve (3) is connected to an adjacent side wall portion (9A or 9B) of the tubular member (5).

24. A bag according to claim 23, wherein the tubular member (5) is made of a polymeric material.

25. A bag according to claim 23, wherein the tubular member (5) is made of a woven polyolefin or a woven polypropylene material.

26. The bag of claim 23, wherein the number of holes (29) is two or more, and the holes (29) are arranged in any relative configuration with respect to each other.

27. The bag of any one of claims 23 to 26, wherein the first sealing strip (10) and/or the second sealing strip (25) are made of a woven or nonwoven material.

28. The bag of claim 27, wherein the first sealing strip (10) and/or the second sealing strip (25) are made of a polymeric material.

29. The bag of claim 27, wherein the first sealing strip (10) and/or the second sealing strip (25) are made of a coated or laminated woven polyolefin or woven polypropylene material.

30. The bag of any one of claims 23 to 26, wherein the first and second sealing strips are pre-applied on their surfaces with an adhesive that attaches themselves to the bag.

31. Device (1) for producing bags (2) with at least one valve (3), characterized in that it comprises:

a) -a supply unit (101) for providing a tubular member (5), said tubular member (5) being made of fabric and having a first open end (7) and a second open end (8);

b) -a first closing unit (102) for closing said first open end (7) of said tubular element (5) by means of a first sealing band (10);

c) A valve forming unit (103) for forming the valve (3) of the bag (2) by folding a corner (13) of the second open end (8) inwardly into the interior of the tubular member (5);

d) -a cutting unit (104) for cutting off an edge strip (22) of the second open end (8);

e) A second closing unit (105) for closing the second open end (8) by means of a second sealing band (25);

wherein the device (1) further comprises a punching unit (108) for punching at least one hole (29) in at least one side wall portion (9A and/or 9B) of the tubular member (5) before closing the second open end (8) by means of a second closing unit (105), wherein the hole (29) is positioned such that a connection between the second sealing band (25) and at least one side wall (19) of the valve (3) is established when the second sealing band (25) is attached.

32. The device according to claim 31, wherein the tubular member (5) is made of a polymeric material.

33. The device according to claim 31, wherein the tubular member (5) is made of a woven polyolefin or a woven polypropylene material.

34. The device according to claim 31, wherein the punching unit (108) is located upstream of at least the second closing unit (105).

35. The device (1) according to any one of claims 31 to 34, wherein the first closing unit (102) and/or the second closing unit (105) has a bonding or sealing means (28) for connecting the first sealing band (10)/second sealing band (25) to the first open end (7)/second open end (8) of the tubular member (5).

36. The apparatus (1) according to claim 35, wherein said bonding or sealing device (28) is capable of performing hot air welding or ultrasonic welding.

37. The device (1) according to any one of claims 31 to 34, wherein the device (1) further comprises an adhesive unit for connecting at least one side wall (19) of the valve (3) to an adjacent side wall portion (9A or 9B) of the tubular member (5) by means of glue.

38. The device (1) according to any one of claims 31 to 34, wherein the device (1) further comprises a welding unit (106) for connecting at least one side wall (19) of the valve (3) to an adjacent side wall portion (9A or 9B) of the tubular member (5) by means of a welding process.

39. The device (1) according to claim 38, wherein the welding process is an ultrasonic welding process.

40. The device (1) according to claim 38, wherein the welding unit (106) comprises a separating element (20) insertable between the side walls (19) of the valve (3) during the welding process.

41. The device (1) according to claim 40, wherein the separating element (20) is a separating layer (21) made of metal.

42. The device according to claim 31, wherein the punching unit (108) has a slidable bolt (30) for punching the hole (29) and a support element (31) provided under the tubular (5) when punching the hole (29).