JP3534232B2 - Molding method of rectangular cylindrical flexible container bag - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates to a method of molding a square cylindrical flexible container back grayed used in case of mass transport granular product of the resin pellets and the like.

[0002]

2. Description of the Related Art Conventionally, the above-mentioned rectangular tubular flexible container bag is disclosed in Japanese Utility Model Laid-Open No. 48-103441.

According to what is particularly shown in FIG. 3 of the above-mentioned publication, each part of the flexible container bag is formed of a thermoplastic and flexible resin sheet material.

The bag body of the flexible container bag described above is provided with a rectangular tubular sheet whose axis is substantially vertical. This rectangular tubular sheet is formed by integrally joining a plurality of (4) flat sheet members arranged side by side around the axis. The above-mentioned sheet materials have the same length in plan view, and therefore,
The rectangular tubular sheet has a rectangular tubular shape with a square cross section.

The bag body has a ceiling sheet that closes an opening (upper end side opening) in the axial direction of the rectangular tubular sheet and an opening (lower end) in the axial direction of the rectangular tubular sheet. And a bottom sheet that closes the side opening), and the bag body has a rectangular parallelepiped shape as a whole.

A cylindrical sheet is provided so as to project outward (upward) from the ceiling sheet substantially on the axis, and the internal space of the cylindrical sheet is for supplying products for communicating the inside and outside of the bag body. It is used as an inlet. Further, a cylindrical sheet is provided so as to project outward (downward) from the bottom sheet,
The inner space of the cylindrical sheet serves as a discharge port for discharging the product, which communicates the inside and outside of the bag body.

Inside the bag body, the connecting sheets are respectively located in the corner spaces sandwiched by the sheet materials adjacent to each other around the axis, and straddle the midway portions of these sheet materials in the longitudinal direction. It is provided.

As seen in a plan view of the bag body, each end edge of the connecting sheet is abutted with a midway portion in the longitudinal direction of the sheet material.

Reinforcing sheets are respectively positioned at the corners on the acute angle side and the obtuse angle side formed by the midway portion of the sheet material and the edge of the connecting sheet, and one end portion of each reinforcing sheet heats the sheet material. The other end portions are welded to each other and are heat-welded to the edge of the connecting sheet, whereby the both sheet materials are firmly connected to each other by the connecting sheet and the reinforcing sheets. .

When a product is transported using the flexible container bag, first, the discharge port is closed and the product is supplied and stored in the bag body through the injection port. Next, the inlet is closed and the flexible container bag is transported to the destination. Therefore, the product can be discharged from the bag body by opening the discharge port.

During the transportation of the product by the flexible container bag, the bag body tends to be deformed into a circular cross section in a plan view due to the pressure of the product stored in the bag body. However, such deformation of the bag body is suppressed by the connecting sheets and the reinforcing sheet.
For this reason, the bag body is reliably shaped so as to maintain the rectangular tubular shape in cross section, and the easy handling of the flexible container bag during the transportation is ensured.

[0012]

By the way, the following problems may occur in the above-mentioned conventional techniques.

First, as described above, the deformation of the bag body due to the pressure from the product stored in the bag body is suppressed by the connecting sheets and the reinforcing sheets, but the number of these reinforcing sheets is large. , This flexible container bag has a large number of parts,
The configuration is complicated.

Therefore, it is conceivable to delete either one of the reinforcing sheets at each end of the connecting sheet to simplify the structure of the flexible container bag. However, in this case, a gap is likely to be formed between the intermediate portion of the sheet material on the side where the reinforcing sheet is removed and the edge of the connecting sheet.

Therefore, when the fine-grained product stored in the flexible container bag is discharged,
Part of the fine-grained product may remain in the gap,
When this occurs, the remaining fine particles are mixed with the product of another material stored in the flexible container bag thereafter, which is not preferable.

Secondly, in the above-mentioned conventional technique, the space surrounded by both adjacent sheet materials and the connecting sheet connecting these sheet materials with each other has a triangular cross section and is narrow.

Therefore, when the reinforcing sheet located in the space among the reinforcing sheets is to be heat-welded to the sheet material or the connecting sheet while being pressed by the pressing roller, the pressing roller to the space is pressed. It's difficult to insert, so
The work of molding the flexible container bag having the above configuration may be complicated.

The present invention has been made by paying attention to the above circumstances, and when the product is stored in the bag body of the flexible container bag, the rectangular tubular shape of the bag body is surely maintained. In addition, even in this case, the structure of the flexible container bag is simplified, and when the product stored in the bag body is discharged, a part of this product is It is possible to prevent it from remaining in the body
When molding a flexible container bag
It is an object of the present invention to facilitate the molding work of this flexible container bag.

[0019]

[Means for Solving the Problems] The present invention for solving the above problems is as follows .

The invention according to claim 1 is a rectangular tubular flexible connector.
A method of forming a container bag,

The bag body 2 of the flexible container bag 1 is a rectangular tubular sheet 4 formed by joining a plurality of flat sheet materials 5 arranged side by side around an axis 3 to each other. And a corner space 16 sandwiched between the adjacent sheet materials 5 and 5 around the axis 3 inside the bag body 2.
And a connecting sheet 17 is provided so as to straddle these sheet materials 5 and 5 .

As seen from the line of sight along the axis 3, the edge of the connecting sheet 17 is formed integrally with each of the sheet members 5 in a direction away from the corner space 16 corresponding to the edge. The extension piece 18 that is made to extend is provided, and the extension pieces 18 are heat-welded W1 to the sheet materials 5 and 5 to form the sheet material 5 and the sheet material 5.
The one end portion 20 is located at a corner portion on the acute angle side formed by the edge of the connecting sheet 17 coupled to the connecting sheet 17 via the extension piece 18.
Is provided on the sheet material 5 by heat welding W2, and the other end 21 is formed on the end edge of the connecting sheet 17 by heat welding W3 .

Molding of the above flexible container bag
On the occasion of

[0024] Also not a, the other end portion 21 of the reinforcing sheet 22 is thermally welded W3 each end edge of the connecting sheet 17 (FIG. 4),

Next, a non-thermoplastic flat mold release material 29 is interposed between one end 20 and the other end 21 of the reinforcing sheet 22 having a substantially V shape (one-dot chain line in FIG. 4). On the other hand (FIG. 4), with the extension piece 18 and the one end portion 20 of the reinforcing sheet 22 extending in opposite directions (FIG. 5), the sheet material 5 and the extension piece 18 are provided. And put them on top of each other and heat this stack
The sheet material 5 and the extension piece 18 are pressed to heat-weld W1, and the sheet material 5 and one end portion 2 of the reinforcing sheet 22 are pressed.
0, the release material 29, the other end 21 of the reinforcing sheet 22, and the connecting sheet 17 are overlapped with each other ,
The sheet material 5 and the reinforcing sheet by heating and pressing
The one end portion 20 of 22 is heat-welded W2 (FIG. 6).

It should be noted that by interposing a release material 29 between the one end portion 20 and the other end portion 21 of the reinforcing sheet 22, the extension piece 18 and the one end portion 20 of the reinforcing sheet 22 are set in opposite directions. Either the extension may be preceded, or the extension may be performed almost simultaneously. Further, either of the above-mentioned two superpositions may be preceded, or may be almost simultaneously performed. Further, both of the heat welding W1 and W2 may be preceded.

[0027] to exit vent the release material 29 from between the end portion 20 and the other end 21 of the reinforcing sheet 22 (Fig. 7).

According to the invention of claim 2 , in addition to the invention of claim 1 , the extension piece 18 is superposed on the sheet material 5, and the sheet material 5, one end portion 20 of the reinforcing sheet 22, a release material 29, The other end portion 21 of the reinforcing sheet 22 and the connecting sheet 17 are superposed on each other, and the superposed bodies are heat-welded W1 and W2 almost at the same time (FIG. 6).

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 3, reference numeral 1 is a flexible container bag.

The bag body 2 of the flexible container bag 1 is provided with a rectangular tube-shaped sheet 4 shown so that its axis 3 is substantially vertical. The rectangular tube-shaped sheets 4 are arranged side by side around the axis 3. A plurality of (four) flat sheet materials 5 to be formed are integrally joined to each other and molded. When the flexible container bag 1 is viewed along the axis 3 (in a plan view of the flexible container bag 1), the sheet members 5 have the same length, so that the rectangular tubular sheet 4 is It has a rectangular tubular shape whose cross section is square.

The bag body 2 has a ceiling sheet 6 that closes an opening (upper end side opening) on one end side of the rectangular tubular sheet 4 in the axial direction, and the other end of the rectangular tubular sheet 4 in the axial direction. The bag body 2 has a bottom sheet 7 that closes a side opening (a lower end side opening), and the bag body 2 has a rectangular parallelepiped shape as a whole.

A cylindrical sheet 10 is provided so as to project outward (upward) from the ceiling sheet 6 approximately on the axis 3.
The inner space of the cylindrical sheet 10 serves as an injection port 12 for supplying the product 11 which communicates the inside and outside of the bag body 2. Further, a cylindrical sheet 13 is provided so as to project outward (downward) from the bottom sheet 7, and the internal space of the cylindrical sheet 13 is a discharge port for discharging the product 11 that communicates the inside and outside of the bag body 2. It is said to be 14.

Inside the bag body 2, a corner space 1 sandwiched between the adjacent sheet materials 5 and 5 around the axis 3
6, and a connecting sheet 17 is provided so as to straddle midway portions of the both sheet materials 5 and 5 in the longitudinal direction.

As seen in a plan view of the bag body 2,
Each end edge of the connecting sheet 17 is abutted against the midway portion of the sheet material 5 in the longitudinal direction.

As seen in a cross section of the bag body 2 in a plan view of the flexible container bag 1, the flexible container bag 1 extends in the direction away from the corner space 16 along each sheet material 5 corresponding to each edge of the connecting sheet 17. Extending pieces 18 extending integrally from each edge are provided. Almost all of the extension pieces 18 are surface-bonded to the midway portions of the sheet materials 5 in the longitudinal direction, and are almost entirely heat-welded to W1.
The middle part and each edge of the connecting sheet 17 are firmly bonded to each other by the thermal welding W1 of the extending piece 18.

Further, a corner portion on an acute angle formed by a midway portion of the sheet material 5 and an end edge of the connecting sheet 17 joined to the sheet material 5 through the thermal welding W1 of the extending piece 18. Is provided with a reinforcing sheet 22 having a substantially V-shaped cross section. The one end portion 20 of the reinforcing sheet 22 is almost entirely surface-bonded to the midway portion of the sheet material 5 in the longitudinal direction, and is almost entirely heat-welded W2. The part 21 is surface-bonded to the edge of the connecting sheet 17 almost entirely, and is heat-welded W3 almost entirely.

Therefore, the intermediate portions of the sheet materials 5 and the intermediate portions of the sheet materials 5 are connected to each other by the thermal welding W1 of the extending piece 18 to the intermediate portions of the sheet materials 5 and the thermal welding W2 and W3 of the reinforcing sheet 22. The edges of the sheet 17 are firmly connected to each other, that is, the sheet materials 5 and 5 are firmly connected to each other by the connecting sheet 17 and the reinforcing sheet 22.

Both sheet materials 5, which are adjacent to each other around the axis 3,
5 and a connecting sheet 17 connecting the respective intermediate portions of the sheet members 5 and 5 to each other, the corner space 16 is
In a plan view, it has an approximately isosceles triangular shape.

Communication ports 24, 24 are formed between the ceiling sheet 6 and the bottom sheet 7 and the upper and lower edges of the connecting sheet 17, so that the connecting sheet 17 extends in the longitudinal direction (vertical direction).
A plurality of (two) communication holes 25, 25 are formed in the middle part. The corner space 16 and the internal space on the axial center 3 side of the rectangular tubular sheet 4 are connected to the communication ports 24 and the communication holes 2 respectively.
5, the product 11 can be stored in the corner space 16 through these 24 and 25.

When the product 11 is transported using the flexible container bag 1, first, the discharge port 14 is closed, and the product 11 is supplied and stored in the bag body 2 through the injection port 12. Next, the injection port 12
Then, the flexible container bag 1 is transported to the destination. Therefore, when the discharge port 14 is opened, the product 11 can be discharged from the bag body 2.

Flexible container bag 1 described above
During the transportation of the product 11 by the above, the bag main body 2 tends to be deformed into a circular cross section in a plan view due to the pressure of the product 11 stored in the bag main body 2. However, such a deformation of the bag body 2 is caused by the connection sheets 17 and the reinforcing sheet 2 described above.
2 and is suppressed. For this reason, the bag body 2 is surely shaped so as to maintain the cross-section rectangular tube shape, and many flexible container bags 1 can be arranged side by side in an orderly manner or stacked so as to be stable. Easy handling of the bag 1 is ensured.

Further, in the above case, conventionally, two reinforcing sheets 22 are provided for each edge of the connecting sheet 17.
However, in the above embodiment, there is only one, and the number of parts of the flexible container bag 1 is reduced accordingly, and the flexible container bag 1
The configuration of becomes simple.

Further, as described above, the piece 18 extending from the edge of each connecting sheet 17 in the direction away from the corner space 16.
Is extended and heat-welded to the sheet material 5 by W1,
Further, a reinforcing sheet 22 is provided at a corner on an acute angle formed by the midway portion of the sheet material 5 and an edge of the connecting sheet 17, and one end portion 20 and the other end portion 21 of the reinforcing sheet 22 are the sheet material. 5 and the connecting sheet 17 are heat-welded W2 and W, respectively.
It has been made three.

Therefore, the reinforcing sheet 22 prevents the gap between the midway portion of the sheet material 5 and the edge of the connecting sheet 17 from being formed as described in the prior art.

Therefore, when the product 11 stored in the bag body 2 is discharged, a part of the product 11 is prevented from remaining in the bag body 2.

Next, a method for molding the flexible container bag 1 will be described.

In FIG. 4, a long sheet which is a material of each sheet material 5 of the square tubular sheet 4 is in a roll shape, and is fed from the roll-shaped body onto a flat work surface 27 extending in the horizontal direction. Be done. At this time, the long sheet is cut into a length corresponding to the entire circumference of the square tubular sheet 4, and this is made into the square tubular sheet material 26 (first step).

On the other hand, the connecting sheet 17 and the extending pieces 1 integrally extended from the end edges of the connecting sheet 17.
8 is formed, and the other end portion 21 of each reinforcing sheet 22 is attached to the edge of each connecting sheet 17.
Using a heat welding means such as a heating plate.
(Second step).

Next, the one end 20 of the reinforcing sheet 22 is bent toward the other end 21 (one-dot chain line in FIG. 4) to make the cross section of the reinforcing sheet 22 into a substantially doglegged shape. A non-thermoplastic, flat mold release material 29 is interposed between one end 20 and the other end 21 of 22. This release material 2
9 has flexibility, Teflon sheet, silicon sheet,
Alternatively, it is made into paper or the like (third step).

In FIG. 5, the sheet material 5 and the extension piece 18 are arranged in a state where the extension piece 18 and the one end portion 20 of the reinforcing sheet 22 extend in directions opposite to each other. Overlap each other. Further, the sheet material 5, the one end portion 20 of the reinforcing sheet 22, the release material 29, the other end portion 21 of the reinforcing sheet 22, and the connecting sheet 17 are overlapped with each other. The sheet material 5, the connecting sheet 17, the extension piece 1
8 and the reinforcing sheet 22 are blown with hot air 31 to heat them, and at the same time, the above-mentioned stacked bodies are roll-shaped pressing bodies 3 capable of rolling from above.
The whole is pressed by 2 and sandwiched between the pressing body 32 and the work surface 27 (fourth step).

In FIG. 6, the hot air 31 and the pressing body 3 are used.
The sheet material 5 and the extension piece 18 are pressed by the rolling of the sheet material 2.
Are heat-welded W1 and the sheet material 5 and the one end 20 of the reinforcing sheet 22 are heat-welded W2 (fifth step).

In the above case, the reinforcing sheet 22 is used in the third step.
Interposing a release material 29 between the one end 20 and the other end 21 and extending the extending piece 18 and the one end 20 of the reinforcing sheet 22 in opposite directions in the fourth step. Any of these may be preceded, or may be performed at substantially the same time. Further, the superposition of both in the fourth step may be preceded by any of them, or may be performed at almost the same time. Further, the heat welding W1 of the sheet material 5 and the extension piece 18 in the fourth step,
Thermal welding W between the sheet material 5 and the one end portion 20 of the reinforcing sheet 22
2 means that either one is heat-welded first, and then
The other heat welding may be performed, and the above-mentioned heat welding W1, W2
May be nearly simultaneous.

In the fifth step, the one end portion 20 and the other end portion 21 of the reinforcing sheet 22 are pressed against each other by the pressing by the pressing body 32 so as to be heat-welded to each other. Since the mold release material 29 is interposed between them, the one end portion 20 and the other end portion 21 are prevented from being thermally welded to each other.

In FIG. 7, the reinforcing sheet 22 is obtained by separating the sheet material 5 and the connecting sheet 17 from each other.
One end 20 and the other end 21 of the
The release material 29 is extracted from between 21. Then, the heat welding W1 between the sheet material 5 and one end edge of the connecting sheet 17 is performed.
The binding by W3 is completed (sixth step). The release material 29 may be extracted before the other work after the heat welding W2.

In FIG. 8, the joining of the sheet material 5 and the other end edge of the connecting sheet 17 is also achieved by the above first to sixth steps (seventh step).

Hereinafter, the first to seventh steps are repeated to join the connecting sheets 17 to the portion of the square tubular sheet material 26 corresponding to each sheet material 5, and when the joining of a predetermined number of connecting sheets 17 is completed. The longitudinal edges of the rectangular tubular sheet material 26 are joined together by heat welding or the like. Then, the rectangular tubular sheet 4 is formed.

Next, when the ceiling sheet 6, the bottom sheet 7, the cylindrical sheet 10, the cylindrical sheet 13 and the like are joined to the rectangular tubular sheet 4, the molding of the flexible container bag 1 is completed.

Flexible container bag 1 described above
According to the molding method of No. 1, the work of heat-welding the sheet material 5 and the extension piece 18 and the work of heat-sealing W2 of the sheet material 5 and the one end portion 20 of the reinforcing sheet 22 are all related to this. The sheets 5, 17, 18, 21, 22, and 29 are simply stacked, heated and pressed, and then the release material 29 is extracted.

Therefore, in the heat welding work, the work of inserting the pressing body 32 into the corner space 16 is unnecessary, and accordingly, the work of molding the flexible container bag 1 can be facilitated. Become.

Further, in particular, if the heat welding W1 and W2 are performed at the same time, the number of steps for molding the flexible container bag 1 is reduced, and thus the molding operation is further facilitated.

Although the above is based on the illustrated example, the rectangular tubular sheet 4 may have a rectangular cross section.
It may be a polygon such as a 3, 5 or 8 octagon. In addition, in the method of molding the flexible container bag 1, first, each one end edge of each connecting sheet 17 is bonded to each sheet material 5 of the rectangular tubular sheet material 26, and then each connecting sheet 17 is connected. The other edges may be joined together.

[0063]

The effects of the present invention are as follows.

The invention according to claim 1 is a prismatic flexible connector.
A method of forming a container bag,

The bag body of the flexible container bag includes a rectangular tubular sheet formed by joining a plurality of flat sheet materials arranged side by side around an axis with each other,
Inside the bag body 2, a connecting sheet is provided so as to be located in a corner space sandwiched between the sheet materials adjacent to each other around the axis and straddle both of these sheet materials .

Seen from the line of sight along the axis, the members integrally extend from the respective end edges in the direction away from the corner space along the respective sheet materials corresponding to the respective end edges of the connecting sheet. Extension pieces are provided, each extension piece is heat-welded to each sheet material, the sheet material, and the end of the connecting sheet joined to the sheet material through the extension piece. A reinforcing sheet having a substantially V-shaped cross section is provided, which is located at a corner on an acute angle formed by the edge and one end of which is heat-welded to the sheet material and the other end of which is heat-welded to the edge of the connecting sheet. Has been.

Therefore, each sheet material and each edge of the connecting sheet are firmly bonded to each other by thermal welding of the extension piece to each sheet material and each of the reinforcing sheet. That is, the two sheet materials are firmly connected to each other by the connecting sheet and the reinforcing sheet.

Therefore, while the product is transported by the flexible container bag, the bag body tends to be deformed into a circular cross section in a plan view due to the pressure of the product stored in the bag body. Is suppressed by the connecting sheets and the reinforcing sheet. For this reason, the bag body is surely kept in the shape of a rectangular tube, and many flexible container bags can be arranged side by side in an orderly manner or can be stacked in a stable manner, which facilitates the flexible container bag during the transportation. Secure handling.

In the above case, conventionally, two reinforcing sheets are provided for each end edge of the connecting sheet. However, according to the present invention, only one sheet is provided. Since the number of parts of the flexible container bag is reduced, the structure of the flexible container bag is simplified.

Further, as described above, the extending piece is extended from the end edge of each connecting sheet in the direction away from the corner space to be heat-welded to the sheet material and connected with the sheet material. A reinforcing sheet is provided at a corner on an acute angle formed by the edge of the sheet, and one end and the other end of the reinforcing sheet are heat-welded to the sheet material and the connecting sheet, respectively.

Therefore, the above-mentioned reinforcing sheet prevents the formation of the gap as described in the conventional technique between the sheet material and the edge of the connecting sheet.

Therefore, when the product stored in the bag body is discharged, it is prevented that a part of the product remains in the bag body, and thus the product is repeatedly stored in the flexible container bag. Mixing of products is prevented.

[0073] Then, upon molding of the flexible container bag,

First, the other end of each reinforcing sheet is heat-welded to each edge of the connecting sheet,

Next, a non-thermoplastic flat mold release material is interposed between one end and the other end of the reinforcing sheet having a substantially doglegged shape, while the extending piece and one end of the reinforcing sheet. In a state that the portion and the extension piece to extend in opposite directions, the sheet material and the extension piece are overlapped with each other ,
The sheet is pressed by heating and pressing this superposed body.
The sheet material and the extension piece are heat-welded, and the sheet material, one end of the reinforcing sheet, the release material, the other end of the reinforcing sheet, and the connecting sheet are superposed on each other, and this superposed body is added.
One end of the above-mentioned sheet material and reinforcing sheet by pressing while heating
Part is heat-welded,

[0076] be out unplug the above-mentioned release material from between the one end and the other end of the reinforcing sheet.

Therefore, after the other end of the reinforcing sheet is heat-welded to the edge of the connecting sheet, the sheet material and the extension piece are heat-welded, and the sheet material and one end of the reinforcing sheet are attached. the the work to be thermally welded, which simply superimposed related sheets, press <br/> pressure while heating the superimposed body, then, is accomplished by extracting the release material.

Therefore, in the heat welding work, the work of inserting the pressing body into the corner space is unnecessary, and accordingly, the work of molding the flexible container bag can be facilitated.

According to a second aspect of the present invention, the extension piece is superposed on the sheet material, and the sheet material, one end of the reinforcing sheet, the release material, the other end of the reinforcing sheet and the connecting sheet are superposed on each other. These superposed bodies are heat-welded at almost the same time.

Therefore, since the heat welding is performed at the same time, the number of steps for forming the flexible container bag is reduced, and the forming operation is further facilitated.

[Brief description of drawings]

1 is a cross-sectional view taken along the line 1-1 of FIG.

FIG. 2 is a side cutaway view of a flexible container bag.

3 is a sectional view taken along the line 3-3 of FIG.

FIG. 4 is a diagram showing first to third steps in a method for molding a flexible container bag.

FIG. 5 is a diagram showing a fourth step in the method of molding a flexible container bag.

FIG. 6 is a diagram showing a fifth step in the method of molding a flexible container bag.

FIG. 7 is a diagram showing a sixth step in the method for molding a flexible container bag.

FIG. 8 is a diagram showing a seventh step in the method for molding a flexible container bag.

[Explanation of symbols] 1 flexible container bag 2 bag body 3 axis 4 square tubular sheet 5 sheet materials 16 corner space 17 Connection sheet 18 Extension piece 20 One end 21 the other end 22 Reinforcement sheet 29 Release material W1-W3 heat welding

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-152554 (JP, A) real-opening Sho 51-129643 (JP, U) real-opening Sho 48-103441 (JP, U) real-opening Sho 57- 49491 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B65D 88/16-88/24

Claims (2)

(57) [Claims] 1. A method for forming a rectangular tube-shaped flexible container bag, wherein the bag body of the flexible container bag is formed by joining a plurality of flat sheet materials arranged side by side around an axis to each other. A rectangular cylindrical sheet is provided, and a connecting sheet is provided inside the bag body in a corner space sandwiched between adjacent sheet materials around the axis, and a connecting sheet is provided so as to straddle these sheet materials. An extension piece integrally extended from each of the edges in a direction away from the corner space along each of the sheet materials corresponding to each of the edges of the connecting sheet when viewed along the center. Is provided, each of these extending pieces is heat-welded to each of the sheet materials, and the acute angle formed by the sheet material and the edge of the connecting sheet joined to the sheet material through the extending pieces. Side corner A reinforcing sheet having a substantially V-shaped cross section is provided, the one end of which is heat-welded to the sheet material and the other end of which is heat-welded to the edge of the connecting sheet. First, the other end of each reinforcing sheet is heat-welded to each end edge of the connecting sheet, and then the non-heat is applied between the one end and the other end of the reinforcing sheet having a substantially doglegged shape. The sheet material and the extending piece are overlapped with each other in a state in which the flat piece of plasticity is interposed and the extending piece and one end portion of the reinforcing sheet are extended in directions opposite to each other. Align , this overlay
The sheet material and the extension piece are pressed by heating and pressing the body.
And the above sheet material, one end of the reinforcing sheet, the release material, the other end of the reinforcing sheet, and the connecting sheet are superposed on each other, and the superposed body is heated.
A method of molding a rectangular tubular flexible container bag, wherein the sheet material and one end of the reinforcing sheet are pressed against each other by heat welding, and the release material is extracted from between the one end and the other end of the reinforcing sheet. 2. An extension piece is superposed on the sheet material, and the sheet material, one end portion of the reinforcing sheet, the release material, the other end portion of the reinforcing sheet, and the connecting sheet are superposed on each other, and these superposed bodies are combined. The method for molding a rectangular flexible container bag according to claim 1, wherein the heat welding is performed at substantially the same time.