CN112739531A

CN112739531A - Method and device for producing storage bags and storage bag

Info

Publication number: CN112739531A
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: 2021-04-30
Anticipated expiration: 2039-09-17
Also published as: MX2021002493A; CN112739531B; TWI764047B; ZA202100871B; WO2020058828A1; TW202019779A; BR112021004899A2; PE20210742A1

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 tube (5) at the second open end (8) inwards, whereafter the second open end (8) is closed by cutting away the edge strip (22) of the tube (5) formed with the valve (3) and by attaching a second sealing strip (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 the valve (3) being smaller than the depth (24) of the valve (3), and wherein a second sealing strip (25) is attached to the second end (8) of the tubular member (5).

Description

Method and device for producing storage bags 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 present invention relates to a method for producing a bag with an integrally formed valve, the resulting bag and an apparatus for producing such a bag.

Background

Bags or sacks have been used to package/store/transport materials such as grains, flours and various industrial materials. There are two main types of bags used: pillow type and box type. Box 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 web by appropriately folding the end to be sewn. Suturing is a simple and economical process that can be performed either manually or automatically. However, the stitching weakens the integrity and strength of the web as the needles pierce the web material. Some manufacturers use high strength materials to compensate for the loss of strength, however, complete sealing of the filler material from the external environment is not possible. 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 the web, which is an economic disadvantage.

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

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

It is well known in the art to provide bags with self-closing valves, for example from AT512459a1, which allow for quick filling and self-closing of the filled bag. The valve is formed in the flat state of the bag by means of a folding device. These bags are usually filled by means of a filling device, such as a filling tube. For this purpose, the valve is deployed and a filling device is inserted into the valve. After the refill fills are received from the bag, the valve closes 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, which can lead to bag breakage. Furthermore, the filling material may leak through the seams, which is particularly alarming when cement is filled into the bag.

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

Accordingly, there is a need for a bag/sack and method of producing the same that overcomes these disadvantages so that the integrity and strength of the web material is not unduly compromised and wherein the seal is strong and integral and has a securely seated valve.

In particular, it is an object of the present invention to provide a bag with an integrated valve which reliably closes the filled bag when the filling device is withdrawn from the valve, prevents leakage of the 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 the 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 band to the first open end of the tubular member;

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

d) cutting away a lower edge strip of the tubular member having the valve formed at the second open end thereof; and

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

A fabric bag 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 non-woven material, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material, preferably coated or laminated, 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 pouch of the present invention comprises:

-a tubular member made of 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 a bag having at least one valve. The apparatus is capable of producing bags from a web of material which may be woven, non-woven, 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 portion of the second open end inwardly to the inside of the tubular member;

d) a cutting unit for cutting off the lower edge band of the second open end;

e) 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 relates accordingly 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 secured valves.

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 the valve to an adjacent side wall portion of the tubular member by means of a welding process.

Fig. 3 shows an alternative apparatus for producing a bag with a secure valve.

Figure 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.

List of parts:

1. device for measuring the position of a moving object

2. Bag (CN)

3. Valve with a valve body

4. Roll of material/fabric

5. Tubular member

6. Circumferential side wall

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

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

9A/9B, flat, tubular member layer

10. First seal tape

11. Roll of first sealing tape

12. Edge of the first open end

13. Corner part

14. Triangle shape

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

16. Longitudinal axis of tubular member

17. Second side edge or second right-angle edge

18. Bevel edge

19. Side wall of valve

20. Separating element

21. Separating layer

22. Lower edge belt

23. Height

24. Depth of field

25. Second seal tape

26. Coil of second sealing tape

27. Edge of the second open end

28. Bonding/sealing device

29. Hole(s)

30. Bolt

31. Supporting element

101. Supply unit for tubular elements

102. First closing unit for first open end

103. Valve forming unit

104. Cutting unit

105. Second closing unit for second open end

106. Welding unit

107. Valve connection unit

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

The type of bag produced, for example 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 a fold. The inventive method and the inventive device can be used to produce 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 consist of ribbons or strips of typical width up to 10 mm and thickness of 15 to 120 microns. The fabric may be coated or may be uncoated. The tubular member has a circumferential sidewall that preferably has no openings or apertures except for a first open end and a second open end. The side wall may comprise several side wall portions. Typically, each sidewall portion defines one side of the produced bag. Due to the flexibility of the material used, the tubular member is preferably substantially flat during manufacture of the bag. In this case, the side wall may be divided into at least two parts, a top wall part and a lower side wall part, 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 prepared for the subsequent step. The step of providing a 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 of continuous tubular members with, in particular, woven fabric. Alternatively, the manufacturing can also be performed separately from and before step a). In this case, the tubular member can simply be removed from a stack having a plurality of 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 at the first open end to the edge of the opposite sidewall portion. The first sealing strip may be removed from the stack with 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 strip preferably has two strip 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 strip may be glued or welded to the tubular member, preferably by means of hot air welding or heat welding. The thermal welding technique may use laser techniques, ultrasonic techniques or any other high frequency technique. The two belt 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 strip at the first open end may be stitched to the tubular, as the load at the stitch may be smaller at the first (upper) open end compared to the second (lower) open end.

The first sealing strip may be made of a woven or non-woven material, in particular a polymer material, preferably a woven polyolefin or a woven polypropylene material, which is preferably coated or laminated, optionally may be pre-applied with an 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 corner. The resulting valve has two opposing side walls such that a 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, in particular by means of a knife, which is formed with a valve at the second open end of the tubular member, is cut off. The cutting portion is preferably a straight cutting portion without any bent 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 that is shorter than its depth. In other words: the height of the valve reduces the width of the lower edge strip that is cut away after folding the corners. This improves the reliability of the self-closing mechanism of the valve in the final bag, as accidental folding of the valve to the outside in response to material filling is prevented. The width of the lower edge band is at least 10 mm, preferably at least 70mm, preferably less than 150 mm. After cutting off the lower edge strip, the tubular member has the final length (i.e. 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, in addition to the valve. The valve is not obstructed by the attachment of the second sealing band. The second sealing strip may be taken out of the stack with sealing strips, or may be cut from a continuous sealing strip, in particular from a roll, corresponding to the attachment of the first sealing strip. 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 strip preferably has two strip portions connected to each other, one at each sidewall 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 strip may be glued or welded to the tubular member. The two belt 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, the second sealing strip at the second open end may be sewn to the tubular member.

The second sealing strip may be made of a woven or non-woven material, in particular a polymer material, preferably a woven polyolefin or a woven polypropylene material, preferably coated or laminated, optionally may be pre-applied with an adhesive.

As a key aspect of the invention, the formed valve is robust such that it does not deploy when filling is complete or under any other circumstances. The simplest way to achieve this is to firmly attach at least one valve wall to the second sealing band. In a preferred method of securing the valve, at least one aperture 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 attaching the second sealing band to the second open end in step e), for example by gluing or welding, preferably hot air welding or heat welding, the at least one sidewall of the valve is connected to the second sealing band by the at least one hole. The second sealing strip may be glued or welded to the tubular member, preferably by means of hot air welding or heat 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 the adjacent side wall of the tubular member, at least one side wall of the valve is connected to the adjacent side wall portion via the second sealing band. The at least one hole is preferably located close to the location of the second open end so that it can be completely covered by the second sealing band.

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

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

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

As shown in fig. 1A and 1B, in a preferred embodiment the inwardly folded corner of the second open end for forming the valve has the shape of a triangle, in particular an isosceles triangle. In this embodiment, the first side (first leg) of the triangle is oriented substantially perpendicular to the longitudinal axis of the tubular member and the second side (second leg) is oriented substantially parallel to the longitudinal axis of the tubular member. As shown in fig. 1A, the first side of the triangle is part of the folded side edge of the flat tubular member before folding the side wall into a fold. Similarly, the second side edge is part of the open edge of the second open end before the fold is formed. The beveled edge connects the sidewall and the second open end.

According to one embodiment of the invention, step d) may comprise cutting away the lower edge strip 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 formed with the valve. The longitudinal axis thereby extends from the first open end to the second open end of the tubular member.

As an alternative to securing the valve so that it does not undesirably open or fold outwardly (i.e. as opposed to the previously described inward folding), at least one side wall of the valve, preferably the bottom edge of the side wall of the valve, is securely connected to an adjacent side wall portion of the tubular member after the valve has been formed according to step c). Preferably, the two side walls of the valve are each connected to a side wall portion of the tubular member adjacent to them.

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 the adjacent side wall of the tubular element by means of a process which performs hot melt adhesive for the purpose of connection. 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 simultaneously to respective adjacent side walls of the tubular member. 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 the mutual connection of the side walls of the valve during the welding process, a separating element, in particular a separating layer preferably made of steel, may be used during the welding process to temporarily space the side walls of the valve from each other. The advantage of the separate element 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, a method involving forming at least one aperture in at least one adjacent sidewall portion through which the second side band is securely attached to one sidewall of the valve; and at least one side wall of the valve, preferably a bottom edge of the side wall of the valve, is securely connected to an adjacent side wall portion of the tubular member.

The invention further provides a fabric bag comprising:

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

-a valve formed by folding a corner of the tubular member at the second end inwardly 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 expanding unintentionally, at least one sidewall of the valve may be connected to an adjacent sidewall portion of the tubular member.

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

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

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

d) a cutting unit for cutting off the lower edge band of the second open end;

The device of the invention is capable of performing the above method. Preferably, the units are arranged sequentially from a) to e). The supply unit may comprise a roll with a wound 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 can be taken out one after the other. The first closing unit may comprise a supply of sealing tape, in particular a V-shaped or U-shaped tape. The sealing strips may be removed from the stack or may be cut from a roll. For cutting, the first closing unit may comprise a knife. Alternatively, the first closure element 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 piece to the inside of the tubular piece. Advantageously, the valve forming unit may further comprise a lifting member which lifts an edge of the second open end of the tubular member to facilitate folding of the corner portion. The cutting unit may include a knife. The second closed cell may be constructed similarly 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 gluing.

In a first embodiment of the device, the first closing unit and/or the second closing unit has a welding device for connecting the first sealing band/the second sealing band to the first/second open end of the tubular element. 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 sidewall portion of the tubular member before closing the second open end by means of the second sealing band, wherein the hole is punched close to the second open end such that when the second sealing band is attached, a connection is established between the second sealing band and the at least one sidewall of the valve.

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

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 element 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 joining 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 stamping unit, which in a preferred embodiment is provided for the same purpose, 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.

In the following, preferred embodiments of the invention will be described with the aid of the accompanying drawings.

Fig. 1 schematically shows an apparatus 1 for producing bags 2 with integrated valves 3, here a production line. The production line has several work stations (from left to right) for producing bags. The sequence shown in fig. 1 is only a preferred embodiment and the individual steps can 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, they are only schematically shown in the figures.

Fig. 1 also shows a web roll 4 from which the tubular members 5 are cut by means of a cutting device, such as a knife or laser cutter (not shown). Each tubular member 5 typically 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 polymer material, preferably a woven polyolefin or a woven polypropylene material. Due to their flexibility, the tubular elements 5 are substantially flat during the manufacturing process as shown. In this flattened state, at least two opposing

side wall portions

9A and 9B of the tubular member 5 are formed with folded

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 pieces 5 may of course simply be taken from a stack or from another production line for producing the tubular pieces 5. The step of cutting or simply removing the tubular member 5 may be generally referred to as the step of providing the tubular member or simply step a). This step may be performed 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, so 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. For this purpose, the first sealing strip 10 may be cut from a continuous roll 11 of strip or alternatively taken from a stack. The length of the first sealing strip 10 may be greater than the width of the first open end 7. There are various ways to attach or bond the first sealing strip 10 to the first open end 7. However, welding or gluing is preferred. For this purpose, a bonding or sealing device 28 is preferred, in particular a device using glue/adhesive bonding (natural or synthetic), or a device using welding techniques such as laser welding, ultrasonic welding or any other high-frequency welding, or a hot air welding device. Such a bonding device 28 may be included in the first enclosure unit 102.

The first sealing band 10 preferably has two band portions (not shown) connected to each other, one for each sidewall 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-shaped or V-shaped cross-section, are thereby attached to the edge 12 of the first open end 7. Alternatively or additionally, the first sealing strip 10 at the first open end 7 may be sewn to the tubular member 5, since the load at the seams may be smaller 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 generally called valve forming unit 103, the valve 3 is formed into the tubular member 5. To this end, the corner 13 at the second open end 8 is folded inwardly into the interior of the tubular member 5. As can be seen in fig. 1, the corner portions 13 are formed, when folded inwardly, as two isosceles triangles 14 having a common side or edge therebetween, the common side being a first side 15 (first right-angle side). 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 element 5. Similarly, a second side (second cathetus) 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 element 5. Finally, the hypotenuse 18 of the triangle 14 is formed by folding the

sidewalls

9A and 9B.

It is clear that the entirety of the valve 3 eventually formed together 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

The bevel 18 is an integral part of the

side walls

9A and 9B.

Although the valve 3 has integrity with the bag in the manner explained herein, in order to prevent the valve from being undesirably unfolded outwards (i.e. as opposed to being folded inwards as described earlier), the device of the present invention is provided with a punch unit 108.

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

side wall portion

9A and 9B by means of a punching 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 relative to each other as long as the second sealing band 25 covers the at least one hole 29 when in its final position. The punching of the hole 29 must be performed 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 aperture 29 may be a through hole passing 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 aperture 29 passes through only one of the respective adjacent

side wall portions

9A and 9B of the tubular member 5. In step e), a second sealing band 25 is finally attached to the second open end 8 using a second welding device 28, which may be part of the second closing unit 105. Welding or gluing 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 hole 29 is positioned close to the second open end 8 so that it can be completely covered by the second sealing band 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 location of the aperture 29 may be predetermined based on the size of the bag and valve. Thus, once the position of the cut made to make the tubular element 5 from the tubular web is known, the action of forming the hole 29 can also be carried out at virtually any time during the method (i.e. even before any of the steps b, c, d and e).

As an alternative to securing the valve using the aperture 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 securely connected to the respective adjacent

side wall portions

9A and 9B of the tubular member 5. This step may be performed by a unit generally 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 flat 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 walls 19 of the valve 3 can be achieved if the side walls 19 of the valve 3 are 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 carried out 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, for example 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 the welding process 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 each other unintentionally 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 an adhesive material, which may be a natural or synthetic adhesive, preferably a hot-melt adhesive. This step may be performed by an adhesive unit, which may be integrated into the valve connection unit 107.

In a further embodiment, the device comprises the aforementioned stamping unit 108, which in the 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 cutting 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, at the second open end 8 of the tubular member, in which the valve 3 is formed, is cut off, for example by means of a knife or another cutting device (not shown). The cut is preferably straight without any curved portions. 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 cut-away lower edge strip 22. 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, since accidental folding of the valve 3 to the outside in response to filling of the material is prevented. The cutting out of the lower edge strip 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 formed with the valve 3.

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 enclosing unit 105, which may be similar to the first enclosing unit 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 kept 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 strip. Like 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. The two band portions of the second sealing band 25, i.e. the sides of the U-shaped 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 sewn to the tubular member 5. The second sealing strip 25 may be glued or preferably welded to the tubular member 5. For this purpose, a further bonding or sealing device 28 may be included in the second closing unit 105.

Since the second sealing strip 25 may be too long and protrude from the bag 2 due to the presence of the valve 3, a sealing strip 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 band 25 that protrudes above the valve 3.

The above-described process carried out with the device 1 produces 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 figure are arranged in the production line in the order of 101, 102, 103, 104 and 105.

The advantages of the bag made using the method and apparatus disclosed herein are apparent.

While the above description contains many specifics, these specifics 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 in light of the above teachings without departing from the spirit and scope of the present invention. Accordingly, the scope of the present invention should be determined not by the illustrated embodiments, but by the appended claims and their legal equivalents.

Claims

1. A method for manufacturing a storage bag (2) having a valve (3), comprising the steps of: providing a tubular member (5), said tubular member (5) being made of a fabric, in particular a polymer material, preferably a woven polyolefin or a woven polypropylene material, having a first open end (7) and a second open end (8); subsequently closing said first open end (7) of said tubular member (5), preferably by attaching a first sealing band (10) to said first open end (7) of said tubular member (5), characterized in that these steps are followed by the following steps:

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

b. cutting off an edge strip (22) of the tubular member (5) formed with the valve (3) 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).

2. A method according to 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).

3. A method as claimed in claim 1 or 2, wherein step b) comprises cutting away 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.

4. The method according to claims 1 to 3, wherein prior to step c) at least one hole (29) is formed in adjacent sidewall portions (9A and/or 9B) to establish a connection between the second sealing band (25) and at least one sidewall (19) of the valve (3) in step c).

5. A method according to claims 1 to 3, wherein after forming the valve (3) according to step a), at least one side wall (19) of the valve (3), preferably 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).

6. Method according to claims 4 and 5, 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 element (5) by means of a welding process, in particular an ultrasonic welding process.

7. Method according to claim 6, wherein during the welding process a separating element (20), in particular a separating layer (21), preferably made of metal, is used to temporarily space the side walls (19) of the valve (3) from each other.

8. The method according to claim 5, wherein said at least one side wall (19) of the valve (3) is connected to the respective adjacent side wall portion (9A or 9B) of the tubular member (5) by means of an adhesive material, preferably by means of a hot-melt adhesive.

9. The method according to claims 1 to 8, wherein the first sealing band (10) and/or the second sealing band (25) is attached to the tubular member (5) by means of welding, preferably hot air welding or ultrasonic welding, or by adhesion using an adhesive.

10. The method of claims 5 to 9, 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.

11. The method according to claims 5 to 10, wherein said second sealing tape covers at least one of said holes (29) after closing said second open end (8).

12. The method of claims 1 to 11, wherein said first and second sealing bands are in the form of a U-shaped or V-shaped cross-section.

13. The method according to claims 1 to 12, wherein the first sealing tape (10) and/or the second sealing tape (25) is made of a woven or non-woven material, in particular a polymer material, preferably a woven polyolefin or a woven polypropylene material, preferably coated or laminated.

14. The method of claims 1 to 13, wherein said first and second sealing strips have pre-applied on their surfaces an adhesive attaching themselves to said bag.

15. A storage bag (2) made of a fabric material, characterized in that it comprises:

-a tubular member (5) made of fabric, in particular a polymeric material, preferably a woven polyolefin or a woven polypropylene material, said tubular member (5) having a closed first end (32), preferably 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) inwards into the interior of the tubular member (5), the height (23) of the valve (3) being smaller than the depth (24) of the valve (3);

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

16. A bag according to claim 15, wherein the wall portion (9A or 9B) has at least one hole (29) formed therein, said at least one hole (29) being covered by said second sealing strip (29).

17. A bag according to claims 15 and 16, wherein at least one side wall (19) of the valve (3) is connected to an adjacent side wall portion (9) of the tubular member (5).

18. A bag according to claim 16, wherein the number of said holes (29) is two or more and said holes (29) are arranged in any relative configuration with respect to each other.

19. The bag according to claims 15 to 18, wherein the first sealing tape (10) and/or the second sealing tape (25) is made of a woven or non-woven material, in particular a polymer material, preferably a woven polyolefin or a woven polypropylene material, preferably coated or laminated.

20. The bag of claims 15 to 19 wherein the first and second sealing strips have pre-applied to their surfaces an adhesive that attaches themselves to the bag.

21. An apparatus (1) for producing a storage bag (2) having 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 a fabric, in particular a polymer material, preferably a woven polyolefin or a woven polypropylene material, 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 member (5), in particular 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 portion (13) of the second open end (8) inwards inside 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 said second open end (8) by means of a second sealing band (25).

22. The device (1) according to claim 21, 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 (9A or 9B) of the valve (9) is established when the second sealing band (25) is attached.

23. The device according to claims 21 and 22, wherein said punching unit is located upstream of at least said second closing unit (105).

24. The apparatus (1) according to claims 21 to 23, wherein said first closing unit (102) and/or said second closing unit (105) have an adhesive or welding device (28) for connecting said first/second sealing band (10, 25) to said first/second open end (7, 8) of said tubular member (5), wherein said welding device (28) is preferably capable of performing hot air welding or ultrasonic welding.

25. The device (1) according to claims 21 to 24, 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.

26. The device (1) according to claims 21 to 25, 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, preferably an ultrasonic welding process.

27. Device (1) according to claim 26, wherein the welding unit (106) comprises a separation element (20), in particular a separation layer (21), preferably made of metal, which can be inserted between the side walls (9) of the valve (3) during the welding process.

28. Apparatus according to claim 22, wherein said punching device (108) has a slidable bolt (30) for punching said hole (29) and a support element (31) provided under said tubular member (5) when punching said hole (29).