Bag making device and bag making method

Abstract

To provide a bag-making apparatus and a bag-making method that can make a packaging bag with suppressed warpage.SOLUTION: This invention relates to a bag making apparatus that heat-bonds a pair of long films 11, 11 while conveying them to manufacture a packaging bag 10, wherein the bag making apparatus comprises a heat-bonding section 40 that forms an outer peripheral seal portion 20 on the pair of films by heat-bonding, and a packaging bag warpage correction mechanism 50 that sandwiches the pair of films and adjusts the height at a position adjacent to the upstream side of the thermal bonding section in the film transport direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a bag making apparatus and a bag making method for producing packaging bags while conveying a pair of long films. [Background technology]

[0002] BACKGROUND ART Packaging bags (pouches) made by thermally bonding flexible resin films have been widely used as packaging containers for packaging various fluid contents, such as sanitary products such as detergents and shampoos, and food products such as soy sauce and seasonings. In particular, they are frequently used as packaging containers called refill pouches, which are used to refill contents into other containers such as plastic bottles and glass bottles. Such packaging bags are manufactured, for example, as shown in Patent Document 1 below, by sequentially unwinding a long, rolled, resin-made raw film while continuously transporting two upper and lower films and a bottom film sandwiched on both sides thereof, and by carrying out an assembly line process of heat sealing both sides in the film transport direction (vertical direction) and cross sections at predetermined intervals extending in the film width direction (horizontal direction), and a cutting process of cutting the film along set cut lines between adjacent packaging bags to separate them into individual packaging bags. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-168147 Summary of the Invention [Problem to be solved by the invention]

[0004] Packaging bags manufactured as described above may experience warping, whereby some or all of the four corners lift when placed flat on a horizontal surface. The cause of warping is believed to be a combination of various factors, including uneven film thickness, slipperiness, biaxially oriented film orientation (twist due to anisotropy), characteristics of the raw film itself, such as pitch elongation and shrinkage during the film lamination process, and different tensions applied to each of the pair of films during transport. If the degree of warping deviates from the acceptable range and falls outside the standard range, the packaging bag loses its commercial value as a defective product, resulting in a reduced yield. Furthermore, packaging bags with non-standard warping can cause various problems, such as poor transport after the cutting process, unstable posture of stacked packaging bags, and jams due to diagonal snagging during the inspection process and even the filling process.

[0005] The present invention is intended to solve these problems, and has an object to provide a bag making device and a bag making method that can make packaging bags with reduced warping. [Means for solving the problem]

[0006] The bag making apparatus of the present invention is a bag making apparatus that produces a packaging bag by thermally bonding a pair of long films while conveying them, and Cut the original film in half width A pair of films A half cut part for obtaining The aforementioned a thermal adhesive portion that forms a peripheral seal portion by thermal adhesion between the pair of films; The present invention is characterized by including a packaging bag warp correction mechanism that sandwiches the pair of films and adjusts their height at a position adjacent to the upstream side of the thermally sealed portion in the film transport direction.

[0007] The bag making method of the present invention is a bag making method in which a pair of long films obtained by cutting a raw film in half widthwise are thermally bonded while being conveyed to produce a packaging bag, the method comprising: A pair of filmsThe present invention is characterized in that a packaging bag warpage correction process is carried out in which the pair of films are sandwiched together and their heights are adjusted before the thermal bonding process in which the peripheral seal portion is formed. [Effects of the Invention]

[0008] According to the bag making device or bag making method of the present invention, the packaging bag warpage correction mechanism clamps a pair of films at an adjusted height upstream of the thermal sealing section, allowing the pair of films to be stacked in a state where warping is reduced, and packaging bags with reduced warping can be easily manufactured. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a flow chart illustrating a bag manufacturing method according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing a part of a bag making apparatus according to an embodiment of the present invention. [Figure 3] (a) is a plan view showing an example of the shape of a packaging bag made by the bag making apparatus of the present invention, and (b) is a plan view showing a schematic example of an example in which packaging bags are made two at a time at one pitch along the film conveying direction. [Figure 4] 3 is a cross-sectional view showing an example of the configuration of a pressing member in the bag making apparatus of FIG. 2. FIG. [Figure 5] FIG. 2 is a schematic cross-sectional view showing a warped state of the packaging bag. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A bag making apparatus and a bag making method according to an embodiment of the present invention will be described below with reference to the drawings.

[0011] As shown in Figure 1, the bag making apparatus of the present invention comprises an unwinding section 30 that unwinds film from an original film, a half-cutting section 31 that cuts the unwound film in half, a stacking section 32 that overlaps the half-cut films 11, 11, a thermal sealing section 40 that thermally seals the overlapped films 11, 11, and a cutting processing section 70 that cuts the thermally sealed films 11, 11. Here, the thermal bonding section 40 is composed of a vertical thermal bonding section 41, a vertical cooling section 42, a horizontal thermal bonding section 43, and a horizontal cooling section 44. Furthermore, the bag making apparatus of the present invention is provided with a packaging bag warp correcting mechanism 50 and a packaging bag warp correcting mechanism 60. The packaging bag warp correcting mechanism will be described in detail later.

[0012] Specifically, as shown in Figure 3(a), the packaging bag 10 produced by the bag making apparatus and bag making method of the present invention is formed into a bag shape by heat-sealing a pair of front and back films 11, 11 to form a peripheral seal portion 20, and the contents are stored in a storage portion 25 inside the peripheral seal portion 20. In this embodiment, the packaging bag 10 has a roughly rectangular outer contour shape, and a side seal portion 21 of the peripheral seal portion 20 is formed on the side peripheral edge of the packaging bag 10, and a bottom seal portion 22 of the peripheral seal portion 20 is formed on the bottom peripheral edge of the film 11. When the packaging bag 10 has a bottom such as a standing pouch, the side seal portion 21 and the bottom seal portion 22 are formed with the film that will become the bottom (bottom film) folded and inserted between a pair of films 11, 11. In the example shown in Figure 3(a), the portion that will become the top seal portion of the packaging bag 10 is left unsealed, but normally the packaging bag is transported to the content filling process with the top seal portion unsealed, and after the content has been filled, the top seal portion is formed by thermal bonding.

[0013] The outer contour shape of the packaging bag 10 manufactured by the bag making apparatus of the present invention is not particularly limited, but since warping (raised corners) is likely to occur in packaging bags with acute corners, such as those with an overall shape that is roughly rectangular or roughly triangular, or those with a nozzle portion that protrudes as a spout for pouring the contents, the bag making apparatus and bag making method of the present invention can be preferably applied to the manufacture of packaging bags with acute corners that are less than a right angle. Furthermore, the shape of the packaging bag manufactured by the bag making apparatus of the present invention is not particularly limited, and various shapes can be used, such as so-called standing pouches, flat pouches, pouches with gussets, and packaging bags in which three sides of a folded film are sealed. Furthermore, the packaging bag may be provided with accessories such as a zipper, or may be provided with easy-tear processing such as notches or weakened lines.

[0014] A specific bag manufacturing method will be described below. In a bag making apparatus according to one embodiment of the present invention, a raw film unwound from a film unwinding section 30 is cut in half widthwise (in half in the film width direction) at a half-cutting section 31 to obtain a pair of films 11, 11. A certain tension is applied to these films 11, 11 by a drive roller or tensioner (not shown), and the films 11, 11 are stacked with their sealant layers facing each other, with the bottom film folded and sandwiched between them, and are intermittently transported in the film transport direction in accordance with the screen pitch (pitch) of a pattern such as pre-printed letters or designs. As shown in Fig. 2, this stack is pressed by a packaging bag warpage correction mechanism 50 and then transported to a vertical heat-sealing section 41. There, heat-sealing is applied in the film transport direction (vertical direction), and the bottom film is heat-sealed to both the front-side film 11 and the back-side film 11 to form a bottom seal section 22. Next, it is cooled in a vertical cooling section 42, and pressed again by a packaging bag warpage correction mechanism 60 provided downstream in the film transport direction, and then transported to a horizontal heat-sealing section 43. There, heat-sealing is applied in the film width direction (horizontal direction), and the side seal section 21 is formed. Next, it is cooled in a horizontal cooling section 44.

[0015] Here, both the vertical heat-sealing section 41 and the horizontal heat-sealing section 43 heat-seal the stack of films 11, 11 at a constant height while maintaining a horizontal position, and the specific heat-sealing mechanism can be the structure of the heat-sealing section (heat seal section) in various conventionally known bag-making devices.

[0016] In the thermal sealing section 40, as shown in Figure 3(b), the film 11 is arranged continuously in the width direction of the film with the top seal portions of the two packaging bags 10 facing each other and the bottom seal portions 22 spaced apart, and the bag is made in a state where one side seal portion 21 (the left side seal portion in Figure 3(b)) is at the front in the film transport direction (x direction in Figure 3(b)). In the lateral heat-sealed portion 43, the side seal portion 21 at the rear end of the first pitch and the side seal portion 21 at the leading end of the second pitch are simultaneously heat-sealed along the film transport direction. In Figure 3(b), the heat-sealed area is indicated by diagonal lines. In this embodiment, in order to improve manufacturing efficiency, the packaging bags 10 are manufactured two at a time at one pitch along the film conveying direction, but they may also be manufactured one at a time at one pitch.

[0017] Thereafter, the packaging bag 10 is cut along the outer contour of the packaging bag 10 (shown by the dashed line in FIG. 3(b)) in the cutting processing section 70. As a result, the packaging bag 10 is formed with the portion that will become the top seal portion remaining unsealed.

[0018] In the present invention, the film transport direction means the transport direction in the thermal bonding section 40, the upstream side in the film transport direction means the side closer to the film unwinding section 30, and the downstream side in the film transport direction means the side closer to the cutting section 70. In this embodiment, the film transport direction is the horizontal direction (leftward (x direction) in FIG. 2). In the present invention, the film flow direction means the direction in which the film actually flows at a certain point in the transport path. The film width direction is the direction perpendicular to the film flow direction, and in the thermal bonding section 40 of this embodiment, the film transport direction and the film flow direction are the same (leftward in FIG. 2 (x direction)), and the film width direction is the direction perpendicular to these (direction perpendicular to the paper surface in FIG. 2 (y direction)). The height direction is a direction perpendicular to the film flow direction and the film width direction. In this embodiment, the film flow direction and the film width direction in the packaging bag warp correction mechanism 50 are horizontal, so the height direction is vertical (upward (z direction) in FIG. 2). This example is not limiting, and the film flow direction may be an inclined direction that deviates from a substantially horizontal direction, such as by installing the bag making device itself on a slope or by designing the film flow direction within the bag making device to be an inclined direction, and may be designed to be vertical, for example. In this case, the height direction is not vertical as in this embodiment, but is a direction perpendicular to the film flow direction and the film width direction, and height is defined as the distance in the height direction.

[0019] The packaging bag warp correction mechanism will now be described in detail. The bag making apparatus of the present invention is provided with a packaging bag warpage correction mechanism 50 that sandwiches the pair of films 11, 11 at a position adjacent to the upstream side of the thermal sealing section 40 in the film transport direction and adjusts the height. This makes it possible to easily manufacture packaging bags 10 with reduced warping. Although it is not clear why the packaging bag warpage correction mechanism 50 can suppress warpage of packaging bags, it is thought that the upper and lower (front and back) films 11, 11 are sandwiched between the packaging bag warpage correction mechanism 50, which allows them to come into close contact, allowing air to escape and stretching the film in the direction of the film warpage, thereby reducing the difference in tension between the upper and lower films. Also, by adjusting the height, it is possible to apply a stronger pressing force to the film in the direction of the warpage than to the other film, resulting in a greater reduction in tension. Furthermore, it is thought that the difference in path length between the upper and lower films 11, 11 (the so-called inner ring difference) also reduces the warpage.

[0020] The packaging bag warpage correction mechanism 50 according to this embodiment includes a pressing member 51 that presses the pair of films 11, 11 in a direction in which they come into contact with each other (the vertical direction in FIG. 2), and a pair of free rolls 55 that come into contact with or are close to each other. According to the configuration including the pressing member 51, a packaging bag with reduced warping can be manufactured using a simple mechanism that presses a pair of films 11, 11 in a direction in which they come into contact with each other at a set film passing height. Furthermore, with the configuration in which the pressing member 51 and the pair of free rolls 55 can move vertically together, the stacked state in which warping is alleviated can be maintained and the sheets can be transported stably. Furthermore, pressing member 51 is disposed upstream in the film transport direction from free roll 55. This is preferable in that air can be reliably removed from inside front and back films 11, 11.

[0021] 4, the pressing member 51 is composed of a bar 54, which is made up of a felt member 52 and a metal support member 53 having an insertion hole into which the felt member 52 is inserted, leaving a protruding portion 52A remaining. The two bars 54, 54 are arranged so that the protruding portions 52A of the felt member 52 face each other above and below, and the stack of the pair of films 11, 11 passes between the two bars 54, 54. Due to the flexibility of the felt that constitutes the felt member 52, the pair of films 11, 11 can be pressed into a planar shape with high uniformity, so that a packaging bag in which warping is reliably suppressed can be manufactured. Felt member 52 has a length in the film width direction (length in the y direction) that is equal to or greater than the width of film 11, and a width that allows it to be pressed flat in the film transport direction (width in the x direction). The width of felt member 52 in the film transport direction is 20 to 30 mm. The thickness of felt member 52 in the height direction is 20 to 30 mm. The protruding height of protruding portion 52A of felt member 52 from support member 53 is approximately 10 to 20 mm. Although not shown, Teflon (registered trademark) tape or sheet is attached to each of the surfaces of the felt members 52, 52 that come into contact with the pair of films 11, 11. Teflon is heat resistant and has good surface slip properties, so by providing it on the surface of the felt member 52, it is possible to prevent a decrease in transportability due to friction between the film 11 and the felt member 52. Various materials can be used instead of Teflon.

[0022] The pressing force applied by pressing member 51 to pair of films 11, 11 is preferably 2.0 to 4.0 kgf, and particularly preferably 3.0 to 3.3 kgf. The pressing force due to the weight of upper bar 54 of pressing member 51 alone was 0.4 kgf. If the pressing force applied by the pressing member 51 to the pair of films 11, 11 is too small, there is a risk that insufficient air will be removed, making it impossible to achieve a stacked state in which warping is alleviated.On the other hand, if the pressing force is too large, resistance will be generated in the film transport direction, and the film may meander. The pressing force was measured using an instrumentation conditioner "WGA-700B" manufactured by Kyowa Electronics Co., Ltd. and a small compression load cell "LMA-A (500N)" by sandwiching a 2 mm thick stainless steel plate between the felt member 52 of the upper bar 54 and the load cell and tightening it with a nut.

[0023] The pair of free rolls 55 is made up of two rolls 56, 56 that are not pressed against each other, and is driven by the transport of the pair of films 11, 11. The distance between the pressing member 51 and the free roll 55 is, for example, 10 to 40 mm. If the distance between the pressing member 51 and the free roll 55 is too large, there is a risk that the sheets cannot be stably transported while maintaining a stacked state with reduced warping.

[0024] The packaging bag warp correction mechanism 50 and the thermal sealing section 40 are close to each other, and the separation distance in this embodiment is the distance between the free roll 55 and the thermal sealing section 40 along the film transport direction, and is specifically 50 to 100 mm. If the distance between the packaging bag warp correcting mechanism 50 and the thermally sealed portion 40 is too large, there is a risk that the packaging bags will not be thermally sealed while maintaining the stacked state with the warp alleviated.

[0025] The packaging bag warp correcting mechanism 50 further includes a height adjusting unit (not shown) that adjusts the height (height in the z direction) of the pressing member 51 and the free roll 55 by vertically moving them together. The height adjustment unit allows the pressing member 51 and the free roll 55 to be moved up or down integrally from a reference height, for example, within a range of about ±5 mm. The heights of the pressing member 51 and the free roll 55 are the heights at which the stack of films 11, 11 passes (film passing heights) for each. The film passing heights for the pressing member 51 and the free roll 55 are usually the same, but may differ as long as the effect is not impaired. For example, a difference of about 2 mm is considered to be acceptable.

[0026] The height adjustment unit includes balance adjustment gauges (not shown) arranged on both sides of the pair of films 11, 11 in the film width direction. The balance adjustment gauges are capable of adjusting the heights of both sides (left and right) in the width direction of the pressing member 51, and are adjusted so that the heights of both sides are the same, for example. Alternatively, the heights of both sides can be adjusted to be different from each other. By using a balance adjustment gauge, the film passing height can be easily adjusted with high precision and can be controlled numerically, thereby reducing the time and effort required for adjustment. Here, the heights of the pressing member 51 and the free roll 55 (film passing height) may be adjusted manually or automatically.

[0027] In addition, downstream of the vertical cooling section 42 in the film transport direction and upstream of the horizontal thermal bonding section 43, there is provided a packaging bag warp correction mechanism 60 that clamps the pair of films 11, 11 and adjusts their height. The packaging bag warpage correction mechanism 60 can have the same configuration as the packaging bag warpage correction mechanism 50 provided upstream in the film feeding direction of the vertical heat-sealing portion 41. Specifically, it has a pressing member 61 that presses the pair of films 11, 11 in a direction in which they come into contact with each other, and a free roll 65 provided downstream of the pressing member 61. This pressing member 61 has the same structure as the pressing member 51 of the packaging bag warpage correction mechanism 50. By pressing the pair of films 11, 11 again with a packaging bag warpage correction mechanism 60 provided upstream of the lateral heat-sealed portion 43 in the film transport direction, a further warpage suppression effect can be expected.

[0028] In the bag making apparatus of this embodiment, the packaging bag warpage correction mechanism 60 is disposed adjacent to the downstream side of the vertical cooling section 42 in the film transport direction, but it may be disposed close to the vertical cooling section 42 or close to the upstream side of the horizontal heat sealing section 43. It may also be disposed adjacent to the downstream side of the horizontal cooling section 44 in the film transport direction, or may be disposed in multiple locations.

[0029] Any equipment can be installed between the free roll 55 of the packaging bag warp correction mechanism 50 and the thermal sealing unit 40, as long as it does not substantially change the stacking state of the pair of films 11, 11 obtained by the packaging bag warp correction mechanism 50. For example, in the bag making apparatus of this embodiment, a feed roll (not shown) set at a height slightly higher than the height at which thermal sealing is performed is fixedly installed between the free roll 55 of the packaging bag warp correction mechanism 50 and the thermal sealing unit 40, immediately upstream of the thermal sealing unit 40 in the film conveyance direction. In other words, the packaging bag warp correction mechanism 50 and the thermal sealing unit 40 are adjacently installed via the feed roll.

[0030] The method for correcting warpage of packaging bags will be described in detail below. In the bag making method of the present invention, before the heat sealing process of forming the peripheral seal portion 20 by heat sealing the pair of films 11, 11, a packaging bag warpage correction process is performed by the packaging bag warpage correction mechanism 50. The film passing height at which the packaging bag warpage correction process is performed is set based on the warpage state of the packaging bag 10 made in pre-bag making performed before the actual bag making of the packaging bag 10, or the warpage state of the packaging bag 10 sampled during the actual bag making. This makes it possible to set conditions suitable for the state of the film 11 to be used. The film passing height at which the packaging bag warpage correction process is performed is set by feedback so that the film moves relatively upward when the completed packaging bag 10 is in a downward warp state with the end portions lowered as shown in FIG. 5( a), and moves relatively downward when the completed packaging bag 10 is in an upward warp state with the end portions raised as shown in FIG. 5( b). Specifically, the film passing height is set as a height above or below a reference value. By setting the film passing height in this manner, a pressure is applied in a state in which the lowered end portions are pushed up or the raised end portions are pushed down, thereby correcting the stacking state of the pair of films 11, 11 so that the end portions of the packaging bag 10 are closer to the same height as the center portion. This stack of the pair of films 11, 11 is transported to the longitudinal heat-sealing section 41 in a stacked state in which the warpage is reduced and heat-sealed, thereby resulting in a packaging bag 10 with reduced warpage. Furthermore, if the completed packaging bag 10 has a composite warp state in which one end rises and the other falls, the heights in the film width direction of the pressing member 51 and the free roll 55 may be set to different conditions. In this case, the heights in the film width direction of the pressing member 51 and the free roll 55 on the end side that is warped upward are set to a height below the reference value, and the heights in the film width direction of the pressing member 51 and the free roll 55 on the end side that is warped downward are set to a height above the reference value. The upward and downward warping states refer to the warping states when the film is placed on a horizontal table in the same direction as when the films 11, 11 are thermally bonded, that is, in the same direction as the stacked direction of the films 11, 11. The reference value for the film passing height can be the height at which the films 11, 11 pass through the feed roll provided just before the longitudinal heat-sealing portion 41. When repeated adjustments are made, the previous setting value can be used as the reference value. The feedback setting for the film passing height may be performed manually or automatically, or a program may be used that outputs a preferred setting value for an input value for warpage.

[0031] The film passing height at which the packaging bag warpage correction process is carried out is specifically determined by the following procedure. First, the film passing height is set to a standard value, and approximately 200 to 400 pre-bags are made using raw film for actual bag making. A stack of the manufactured packaging bags 10 is placed on a horizontal table, and the amount of warping at the edge (the amount of warping at the corner that is closest to the four corners) is measured using a scale. If the amount of warping exceeds the standard value, the film passing height is adjusted. Based on this amount of warping, the height adjustment unit moves the pressing member 51 and the free roll 55 up and down, and this process is repeated as necessary. The film passing height at which the packaging bag warpage correction process is carried out is preferably reset for each raw film lot or each batch process. This is because the characteristics that cause warpage vary depending on the properties of the raw film itself and the production lot, and the warpage direction is not constant. It is also preferable to measure and correct the height as needed during the actual bag making process.

[0032] The film 11 used to manufacture the packaging bag 10 described above is made up of multiple layers laminated in the thickness direction, and at least the innermost layer has a heat-sealable layer. One example of the layer configuration of the film 11 is one in which, from the outer surface side, a PET (polyethylene terephthalate) layer, a nylon layer, and a polyethylene layer (innermost layer) having heat-sealability are laminated. The present bag making device and bag making method are particularly useful when using a film that does not contain a metal layer, such as aluminum foil, and that is prone to warping, but film 11 may also contain a metal layer.

[0033] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design modifications can be made without departing from the present invention as set forth in the claims. The order of execution of each process, such as operations, procedures, steps, and stages, in the apparatus and methods shown in the claims, specifications, and drawings, is not specifically stated as "before," "prior to," etc., and may be implemented in any order unless the output of a previous process is used in a subsequent process. Furthermore, even if the operational flow is described using "first," "next," etc. for convenience, this does not mean that the process must be implemented in that order. [Explanation of symbols]

[0034] 10 packaging bags 11 Film 20 Periphery seal 21 Side seal part 22 Bottom seal part 25 Storage section 30 Unwinding section 31 Half cutting section 32 Stacking section 40 Heat bonding part 41 Vertical heat-sealed section 42 Vertical cooling section 43 Lateral thermal bonding part 44 Lateral cooling section 50 Packaging bag warp correction mechanism 51 Pressing member 52 Felt material 52A Protrusion 53 Support member 54 Bar 55 Freerolls 56 rolls 60 Packaging bag warp correction mechanism 61 Pressing member 65 Freerolls 70 Cutting section

Claims

1. A bag making device that produces a packaging bag by thermally bonding a pair of long films while conveying the films, a half-cutting section for cutting the raw film in half to obtain a pair of films; a thermal adhesive portion that forms a peripheral seal portion by thermal adhesion between the pair of films; a packaging bag warpage correction mechanism that sandwiches the pair of films and adjusts their height at a position adjacent to the upstream side of the thermally sealed portion in the film transport direction.

2. The packaging bag warpage correction mechanism has a pressing member that presses the pair of films in a direction in which they come into contact with each other, 2. The bag making apparatus according to claim 1, further comprising a height adjustment unit that enables the pressing member to move up and down.

3. 3. The bag making apparatus according to claim 2, wherein the height adjustment unit has a balance adjustment gauge on each of both sides of the pair of films in the film width direction.

4. 4. The bag making apparatus according to claim 2, wherein the pressing member has a felt member disposed so as to face the pair of films.

5. 5. The bag making apparatus according to claim 2, wherein the pressing force of the pressing member against the pair of films is 2.0 to 4.0 kgf.

6. the packaging bag warpage correction mechanism includes the pressing member and a pair of free rolls that are in contact with or close to each other, 6. The bag making apparatus according to claim 2, wherein the height adjustment unit allows the pressing member and the free roll to move together in the vertical direction.

7. 7. The bag making apparatus according to claim 6, wherein the pressing member is disposed upstream of the free roll in the film transport direction.

8. 8. The bag making apparatus according to claim 6, wherein the distance between the pressing member and the free roll is 10 to 40 mm.

9. 9. The bag making apparatus according to claim 6, wherein the distance between the thermally sealed portion and the free roll or the pressing member is 50 to 100 mm.

10. The thermally sealed portion includes a vertically directed thermally sealed portion that thermally seals the outer peripheral seal portion extending in the film conveyance direction of the packaging bag, and a horizontally directed thermally sealed portion that thermally seals the outer peripheral seal portion extending in the film width direction of the packaging bag, 10. A bag making apparatus according to claim 1, further comprising a packaging bag warpage correction mechanism that clamps the pair of films downstream in the film transport direction of either the vertical heat-sealing section or the horizontal heat-sealing section, which is located upstream in the film transport direction.

11. A bag making method for producing a packaging bag by thermally bonding a pair of long films obtained by cutting a raw film in half widthwise, while conveying the films, comprising: A bag manufacturing method in which a packaging bag warpage correction process is carried out in which the pair of films are sandwiched together and their heights are adjusted before the thermal bonding process in which a peripheral seal is formed on the pair of films.

12. The packaging bag warpage correction step is performed using a pressing member that presses the pair of films in a direction in which they come into contact with each other, The pressing member is movable in the up and down direction, The bag manufacturing method according to claim 11, wherein the film passing height in the packaging bag warpage correction step is set based on the warpage state of the packaging bag.

13. The packaging bag warpage correction process is performed by the pressing member and a pair of free rolls that are in contact with or close to each other, The bag making method according to claim 12, wherein the pressing member and the free roll are movable together in the vertical direction.

14. 14. The bag making method according to claim 12 or 13, wherein the film passing height in the packaging bag warpage correction process is set by feedback so that the film passing height moves relatively upward when the end of the manufactured packaging bag is in a downward warp state, and moves relatively downward when the end of the manufactured packaging bag is in an upward warp state, with the end of the manufactured packaging bag rising.

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