JP3437552B2 - Method of forming square bottom bag made of synthetic resin, and rectangular parallelepiped closed bag using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a square bottom of a synthetic resin square bottom bag, and a rectangular parallelepiped closed bag using the same.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a square bottom bag from a flat tube made of a synthetic resin film having side gusset portions, a flat bottom tube is formed by orthogonally crossing one open end of the flat tube. The bottom of the corner was formed by welding and cutting.

Further, since it is difficult to directly form a square bottom bag from a flat tube made of a synthetic resin film which does not become a side gusset portion, in Patent No. 2027390, a flat bag produced by a general automatic bag making apparatus is used. An invention has been disclosed in which a means for manufacturing a square-bottomed bag by processing a rectangular-shaped synthetic resin bag is adopted so that the square-bottomed bag can be easily mass-produced. According to this, by opening and closing a pair of upper and lower vertical opening rods and a pair of left and right horizontal opening rods, by folding the folding position of the flat rectangular synthetic resin bag from both sides of the bag to the center, The square bottom bag is made easily. When folding the bag, a pair of left and right triangular cusps are formed exactly symmetrically on the bottom of the bag, so adjust the cutting position of the cusps according to the square base of the desired size. The square bottom bag is manufactured by welding.

However, the above patent for manufacturing a square bottom bag by processing a flat rectangular synthetic resin bag manufactured by a general automatic bag manufacturing apparatus is disclosed in the above patent. There is also a problem that the energy consumption is large and the cost is high because the heat welding and the cutting are performed when the bag is molded, and the heat welding and the cutting are also performed in the step of molding the square bottom bag. In addition, since the folding position of the bag is folded from both sides of the bag to the center, the fold lines on both sides of the bag appear in the center of the bag, which may spoil the appearance.

[0005]

[Purpose] Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to directly form a square bottom bag from a flat tube made of a synthetic resin film which is not folded and becomes a side gusset portion. The present invention provides a novel method for forming a rectangular bottom bag made of a synthetic resin, and a rectangular parallelepiped closed bag body using the method.

[0006]

In order to solve the above problems, the method for forming a corner bottom of a synthetic resin square bottom bag according to the present invention is configured as follows.

That is, the first aspect of the present invention is characterized by the following process steps. 1. Cylindrical tube 1 made of synthetic resin film
Is flattened, and 1 / of the flat tube width w from the opening edge 10
Bottom fold line 1 at a distance of 2 and parallel to the opening edge 10
1, the opposite corner portions 10a of the flat tube 1 are folded so as to be close to each other, and the opening edge 1
0 is linearly aligned to form a flat square shape, and the bottom fold line 11 is sandwiched between the mountain fold hypotenuses 12b extending symmetrically from both ends thereof.
1. A bifurcated portion forming step of forming a bifurcated portion 12 composed of two opposing triangular pieces 12a formed by 1. In the triangle piece 12a on the one side, the opening edge 10 on the bottom edge line 13 parallel to the bottom folding line 11 is caused, and the triangle piece 12 on the other side from the bottom edge line 13 is caused.
2. An insertion space forming step of forming a rectangular insertion space 13a opened on the side of the opening edge 10 by overlapping with a. 3. A bottom plate setting step of inserting the rectangular bottom plate 2 fitted with the insertion edge 13b of the insertion space 13a formed in the insertion space forming step, leaving a predetermined width, into the insertion space 13a. 4. A cutting and welding step of heating and welding the insertion edge 13b of the insertion space 13a and the triangular piece 12a on the other side, and cutting the triangular piece 12a on the other side extending from the heat welding position. The bottom plate 2 is formed by expanding the flat tube 1
A corner bottom forming step of forming a corner bottom following the above. In the cutting and welding step, the cutting and welding of the triangular pieces 12a are not performed in any order and may be appropriately performed.

Further, in the welding in the cutting and welding step, the overlapping opening edge 10 is sandwiched in a slightly exposed state, the exposed portion is heated and melted, and then further sandwiched by pressing so that the welding is performed. May be. further,
The tube 1 used is to achieve the desired strength,
It may be a multiple tube m in which a plurality of tubes are stacked.

At both ends of the tube 1 having a predetermined distance,
It is also a feature of the present application to form a rectangular parallelepiped closed container by forming a corner bottom by using the method for manufacturing a corner bottom of a corner bottom bag according to any one of claims 1 to 4.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for forming a corner bottom of a synthetic resin square bottom bag according to the present invention and a rectangular parallelepiped closed bag body using the same will be described in detail with reference to the drawings. The corner bottom forming method of the synthetic resin corner bottom bag according to the present embodiment includes respective steps of a forked portion forming step, an insertion space forming step, a bottom plate setting step, a cutting and welding step, and a corner bottom forming step.

FIG. 1 is an explanatory view of a bifurcated portion forming step of the corner bottom forming method in this embodiment. In the bifurcated portion forming step, a flat tube of a cylindrical tube 1 made of a synthetic resin film is prepared, and the flat tube width w from the opening edge 10 is prepared.
The bottom fold line 11 is formed by folding one end at a position which is 1/2 the distance of and parallel to the opening edge 10 to give a crease. Then, with the end 11a of the bottom fold line 11 as a starting point, the opening edges 10 are once expanded so that the opposite corners 10a of the flat tubes are brought close to each other, and this time, they are aligned linearly in the orthogonal direction, and then mountain fold It is folded and formed in a square shape surrounded by each side of. As a result, a forked portion 12 composed of two opposing triangular pieces 12a constituted by diagonally extending oblique sides 12b symmetrically extending from both ends of the bottom folding line 11 orthogonal to the opening edge 10 aligned in a straight line is formed. (Arrow a in FIG. 1).

In the present embodiment, the two triangular pieces 12a forming the bifurcated portion 12 are tilted toward the front side (in the figure) to be flush with the tube 1 (arrow b in FIG. 1). However, this work may be carried out as necessary, and the workability may be taken into consideration, and the work may proceed to the next step while being maintained at a right angle to the flat surface of the tube 1.

2 and 3 are explanatory views of the insertion space forming step of the corner bottom forming method in this embodiment. In the insertion space forming step, first, in the triangular piece 12a on the one side, the opening edge 1 on the bottom edge line 13 parallel to the bottom folding line 11 is formed.
Both 0s are caused to be in line with the vertex 12c (arrow c in FIGS. 2 and 3). Next, the bottom fold line 11 is folded over from the bottom edge line 13 to the other triangular piece 12a which is a symmetrical position to form a rectangular insertion space 13a (arrow d in FIGS. 2 and 3). The bottom edge line 13 is the triangular piece 1
2a is a linear valley fold line connecting both oblique sides 12b, and in the present embodiment, by providing the bottom edge line 13 at a position that internally divides between the bottom fold line 11 and the apex 12c by 1: 2, Inserting space 13 into both hypotenuses 12b of the other triangular piece 12a
It is set so that both ends of the insertion edge 13b of a match.

FIG. 4 is an explanatory view of the bottom plate installation step of the corner bottom forming method in the present embodiment. In the bottom plate installation step, the insertion edge 1 of the insertion space 13a formed in the insertion space formation step described above.
The rectangular bottom plate 2 adapted to leave 3b in a predetermined width (10 to 20 mm in the embodiment) is inserted into the insertion space 13a (arrow e in FIG. 4). Since this bottom plate 2 is for ensuring the strength of the bottom surface, a hard plate material is preferable.

5 and 6 are explanatory views of the cutting and welding step of the corner bottom forming method in this embodiment. In the cutting and welding step, the insertion edge 13 of the insertion space 13a formed in the above step
b and the triangular piece 12a on the other side are heat-welded,
It is a step of cutting the triangular piece 12a on the other side extending from the heat welding position. In the present embodiment, first, the portion of the triangular piece 12a on the other side starting from the heat welding position is cut (arrow f in FIG. 5). Then, the insertion edge 1 of the opening edge 10
Heat resistance from both sides (mainly made of metal) with the exposed portion of 3b and the triangular piece 12a on the other side slightly exposed
While sandwiched by the strip-shaped long bar 3 and held by the sandwiching means such as the clip 4, the exposed portion 14 is heated and melted by the heating iron 5 which is a heating means (arrow g in FIG. 6).

When the melted film material is melted to the extent that it flows into the gap between the elongated bars 3 facing each other,
The fastening force of the clip 4 to the long rod 3 is increased, and the clip 4 is further pressed and clamped to weld the insertion edge 13b (arrow h in FIG. 6).
This holds the bottom plate 2 in the insertion space 13a.

7 and 8 are explanatory views of the corner bottom forming step of the corner bottom forming method in this embodiment. In the corner bottom forming step, the triangular piece 12a on one side is pulled up (see FIG. 7).
I), the end 11a of the bottom fold line 11 is pushed inward to expand the flat tube 1 to form the square bottom 15 following the bottom plate 2 (arrow j in FIG. 8).
FIG. 9 shows a partially cutaway perspective view of the corner bottom portion.

Further, although the corner bottom 15 can be formed on one end side of the cylindrical tube 1 by passing through the above respective steps, the corner bottom 15 is formed with a predetermined distance and at an appropriate position. By forming the injection / exhaust port in the, the corner bottoms 15 are formed at both ends, and a rectangular parallelepiped foldable sealed bag body can be configured. As a result, the bottom plate 2
Since the main body is made of a flexible synthetic resin film except for the above, it can be folded into a flat state when not filled.

[0019]

[Possibility of Other Embodiments] In the cutting and welding step in this embodiment, the triangular pieces 12a may be welded before being cut. Also, a multi-layered tube in which a plurality of tubes 1 are stacked in the cylindrical tube 1 may be used.
The tubes are stacked to form one tube m (see FIG.
0), the bottom plate may be sandwiched between the second and third tubes.

[0020]

[Effect] As described above, according to the method for forming the bottom of the synthetic resin square bottom bag according to the present invention and the rectangular parallelepiped closed bag using the same, the cylindrical tube made of the synthetic resin film is used. From, it is possible to mold a synthetic resin square bottom bag having a closed structure square bottom, and by the bottom plate in the insertion space,
The pressure acting on the corner bottom can be dispersed.

Further, in the welding in the cutting and welding step, the overlapped portions are slightly exposed and sandwiched by a pair of strip-shaped long rods, and the exposed portions are heated and melted to be welded. Therefore, as long as it is a thermoplastic synthetic resin film material, regardless of the material, a large number of sheets can be welded in a stacked state.

Further, the strength is improved as a multiple tube in which a plurality of tubes are stacked in a cylindrical tube, or square bottoms are formed at both ends of the tube to seal both ends.
The use of the rectangular parallelepiped closed bag body makes it possible to obtain a sealed bag body in which a liquid can be sealed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a forked portion forming step of a method for forming a square bottom according to the present embodiment.

FIG. 2 is an explanatory diagram of an insertion space forming step of the corner bottom forming method in the present embodiment.

FIG. 3 is an explanatory diagram of an insertion space forming step of the corner bottom forming method in the present embodiment.

FIG. 4 is an explanatory diagram of a bottom plate installation step of the method for forming a square bottom in the present embodiment.

FIG. 5 is an explanatory diagram of a cutting and welding step of the corner bottom forming method according to the present embodiment.

FIG. 6 is an explanatory diagram of a cutting and welding step of the method for forming a square bottom in the present embodiment.

FIG. 7 is an explanatory diagram of a corner bottom forming step of the corner bottom forming method in the present embodiment.

FIG. 8 is an explanatory diagram of a corner bottom forming step of the corner bottom forming method in the present embodiment.

FIG. 9 is a partially cutaway perspective view of a corner bottom portion of the present embodiment.

FIG. 10 is a partially cutaway perspective view showing a multiple tube according to another embodiment.

[Explanation of symbols]

1 tube 10 Opening edge 10a Opposite corner 11 Bottom fold line 11a end 12 Bifurcation 12a triangular piece 12b hypotenuse 12c vertex 13 Bottom edge line 13a insertion space 13b insertion edge 14 Exposed part 15 Square bottom 2 Bottom plate 3 long bar 4 clips 5 heating trowel m multiple tubes w tube width

Claims (5)

(57) [Claims] 1. A method for forming a corner bottom of a synthetic resin bottom bag, which comprises the following steps. 1. A cylindrical tube (1) made of a synthetic resin film is flattened, and a bottom fold line parallel to the opening edge (10) at a distance of 1/2 of the flat tube width (w) from the opening edge (10). Starting from the end (11a) of (11), the opposite corners (10a) of the flat tube (1) are folded in close proximity to each other, and the opening edges (10) are aligned linearly to form a flat square shape. 1. A forked portion forming step of forming a forked portion (12) composed of two opposing triangular pieces (12a) formed by mountain fold hypotenuses (12b) that symmetrically extend from both ends of the bottom folding line (11). In the triangular piece (12a) on the one side, the opening edge (10) on the bottom edge line (13) parallel to the bottom folding line (11) is caused, and the other side from the bottom edge line (13) is caused. 2. An insertion space forming step of forming a rectangular insertion space (13a) opened on the side of the opening edge (10) by overlapping the triangular piece (12a). Insertion space (13a) formed in the insertion space forming step
3. A bottom plate installation step of inserting a rectangular bottom plate (2) adapted to the insertion edge (13b) leaving a predetermined width. While heat-welding the insertion edge (13b) of the insertion space (13a) and the triangular piece (12a) on the other side,
Triangular piece (12a) on the other side extending from the heat welding position
4. A cutting and welding step of cutting A corner bottom forming step of expanding the flat tube (1) to form a corner bottom following the bottom plate (2). 2. The method for forming a corner bottom of a synthetic resin rectangular bottom bag according to claim 1, wherein the cutting and welding step is carried out after cutting the triangular piece (12a). 3. In the welding in the cutting and welding step, the overlapping opening edges (10) are sandwiched in a slightly exposed state,
The method for forming a corner bottom of a synthetic resin bottom bag according to claim 1 or 2, characterized in that after the exposed portion (14) is heated and melted, the holding portion is further pressed and held for welding. 4. The corner bottom production of a corner bottom bag according to claim 1, 2 or 3, wherein a plurality of tubes are stacked in a cylindrical tube (1) to form a multiple tube (m). Method. 5. A corner bottom (15) is formed on both ends of a tube (1) having a predetermined distance by using the method for manufacturing a corner bottom bag according to any one of claims 1 to 4. A rectangular parallelepiped sealed bag body characterized by.