JPH0470984B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for manufacturing a square bottom of a plastic film bag.

Plastic film bags are currently used in very large quantities for packaging and transporting goods.

Moreover, as such plastic film bags, bags having a so-called square bottom structure having a rectangular bottom are particularly preferred because they are convenient for storing items.

The present invention relates to a novel method for manufacturing a square bottom structure for plastic film bags.

B. Prior Art Various methods for manufacturing the square bottom structure of plastic film bags, which are the object of the present invention, have been proposed.

The known technology closest to the present invention is a manufacturing method in which a plastic film bag is provided with a gusseted fold at the bottom, and the film is fused to the left and right corners of this part at an angle of 45 degrees to form a square bottom.

C. Problems to be Solved by the Invention In the square base manufactured by the above-mentioned known technique, a double-structure right isosceles triangular film is attached to the lower part of the outside of the left and right sides of the square base with the right angle point facing upward. There is. The outer film of this double structure not only does not contribute anything to the strength of the square bottom, but also has a poor appearance and is difficult to handle and inconvenient when used in a bag with a wide square bottom.

Furthermore, when manufacturing a square bottom using the conventional method, the angle of the fused portions at the left and right corners is limited to 45 degrees.

In other words, if this angle is smaller than 45 degrees with respect to the bottom side of the bag, the base of the right-angled isosceles triangle of the extra double film will be longer than the width of the square base, and when the base is made square, the corresponding The adhesive film is loose and the appearance is poor. On the other hand, if this angle is made larger than 45 degrees, the length of the bottom of the adhesive film will be shorter than the width of the square bottom of the bag, and the width of the square bottom will be limited by the adhesive film, causing slack at the bottom of the bag. arise.

The present invention provides a method for manufacturing a square bottom that does not have these drawbacks.

D. Means for Solving the Problems The present invention provides continuous feeding of a long tube-like film or a half-folded strip-like film that is the raw material for the bag, and In the bag-making process of fusing and cutting the original film, a gusset fold is provided at a portion corresponding to the bottom of the bag, a plate is inserted between the folds of the gusset fold, and the plate is cut from the front and back sides. , press a wedge-shaped heated blade against each width of the bag,
The two films on the front and back sides of the plate are fused together, and the wedge-shaped portion of the film is cut off, and a linear hot blade is pressed against the film material for each width of the bag. The square bottom of the plastic film bag is manufactured by fusing and cutting the plastic film bag to form the side edges of the bag body.

The tube-shaped film material used in the present invention can be used as it is produced by inflation processing.

In the step of fusing the casette folded portions in the present invention, a metal plate or the like is inserted between the two sets of casette films in order to prevent the two sets of casette films from being fused together. Then, a wedge-shaped hot blade is pressed against a metal plate or the like from the top and bottom back and front to form a fused portion, and the wedge-shaped unnecessary film surrounded by the hot blade is cut off.

At this time, it is desirable to add a step of mechanically scraping off the separated film or blowing it away with compressed air. If this is not done, the cut off unnecessary film will cause problems in the subsequent process of fusing and cutting the side edges of the bag.

The present invention differs from conventional square bottom manufacturing methods in that the unnecessary film portion is cut off and removed by the fusing and cutting process. Conventionally, they were simply fused by applying a hot iron.

In the fusing process using the wedge-shaped hot blade, it is desirable to align the apex of the wedge-shaped hot blade with the inner fold line of the gusset fold as much as possible.

After or simultaneously with the step of fusing and cutting the corner bottom portion, a portion corresponding to the side edge of the bag body portion is fusing and cutting to fuse and cut the side edge of the bag body. At this time, it is necessary to cut the material so that it coincides with the apex of the wedge shape.

F. Examples The manufacturing method of the present invention will be explained in more detail with reference to Examples.

A long film strip is folded in half along its longitudinal direction, the folds are reversely folded inward, and the film is case-folded to produce a film strip having a gusset fold 5 and a gusset fold 6 as shown in the cross-sectional structure of FIG. Make it.

These gusset folds are performed to form the bottom of the carrier bag into a square bottom structure.

Next, while feeding the gusseted film strip onto a workbench, a front tape film 3 and a back tape film 4 are placed on the upper surface of the front film 1 and the lower surface of the back film 2, respectively, along the upper edges of each. Supply along. The cross-sectional structure of the strip-shaped film assembled in this way when viewed from the side is as shown in FIG.

Next, in a conventional manner, the feeding method of the film strip is switched to intermittent feeding in which the film strip is temporarily stopped, and the film strip is fed onto the fusing workbench. On the fusing workbench, a metal plate 7 is installed between the front film 1 and the back film 2 at the upper edge of the film strip. This metal plate 7 is inserted from above the strip-shaped film.

On the other hand, a metal plate 8 is also installed between the folded parts of the gazette fold 5 and the gazette fold 6.

A gap is provided in the fusion work table where the metal plate is installed, and a hot iron or hot blade can be passed through the gap and pressed against the metal plate from below the table. .

A hot iron is applied to the metal plate 7 on the fusion workbench from above and below. An inverted V-shaped hot iron as shown in FIG. 2 is pressed against the metal plate 7 inside the upper edge of the film strip from above and below at the same time. At this time, an inverted V-shaped carrying part fusion bond 9 as shown in the figure is formed between the front film 1 and the front tape film 3, and the same is formed between the back film 2 and the back tape film 4. As shown in the figure, a handheld fusion is formed, but the front film 1 and the back film 2 are not fused because they are blocked by the metal plate.

At the same time as this fusion process, the metal plate 8 in the folded part between the gusset folds 5 and 6
Press the wedge-shaped hot blade from above and below as shown in the figure. At this time as well, the upper and lower 2
Every two films in a set are fused in the wedge shape of a hot blade to form a square bottom fusion bond 9, and unnecessary films 12 are cut off. The cut off unnecessary film 12 is removed by mechanically scraping it off or by blowing it away with compressed air.

After the fusing step, the film strip is fed to a workbench for the final fusing step. Here, the band-shaped film is fused in the transverse direction in accordance with the position of the apex of the fused wedge provided in the gusset fold, which is the width of the bag. By this fusing and cutting process, it is possible to simultaneously cut the bag body into widths and fuse the side edges of the bag body 11.

F. Effect Through the above steps, a carrier bag as shown in FIG. 3 can be manufactured. According to the square base structure,
When the bag is expanded, it has a structure as shown in Figure 4. Of course, FIG. 4 is shown as an explanatory diagram, and since the film is flexible at the upper edge of the bag, it does not have a square shape as shown in the figure. In this way, the bag can be hung by unfolding the bag, placing items inside, and grasping the tape-like film of the carrying portion from the outside.

In the manufacturing method of the present invention, if the bottom melting step is carried out at an angle of 45 degrees to the lower side of the bag, the bottom of the bag will accurately form a rectangular parallelepiped when the bag is unfolded. However, if this angle is made smaller than 45 degrees, the bottom of the bag will take on the shape of a boat with slanted corners as shown in Figure 6. On the other hand, if the angle is made larger than 45 degrees, a bag can be manufactured in which the bottom is wider than the opening of the bag, as shown in FIG. In this way, by gradually changing the inclination angle of the wedge-shaped thermal blade, and by combining this with changing the width of the fold of the gusset fold 5, it is possible to create bag bodies with a wide variety of shapes. You can make any bag you want.

G. Effects The present invention has made it possible to efficiently manufacture a carrier bag that has the same strength, good appearance, and is convenient to use through a simple process.

Furthermore, the manufacturing method of the present invention makes it possible to manufacture square bottoms with various structures as desired depending on the purpose by changing the inclination angle of the hot blade used in the bottom melting process.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams for explaining one aspect of an embodiment of the manufacturing process of the present invention, and FIGS. 3 and 4 are diagrams for explaining the structure of a carrier bag with a square bottom structure manufactured by this embodiment. FIG. 3 is a plan view of the bag when it is folded, FIG. 4 is a perspective view of the bag when the corner bottom is unfolded, and FIGS.
Each of the figures is a perspective view of a carrier bag having a square bottom structure according to another embodiment of the present invention in a used state. The numbers in the figure are 1: front film, 2: back film, 3: front tape film, 4: back tape film, 5, 6: gusset fold, 7: metal plate for fusing the handbag, 8: metal plate for bottom fusing. , 9; Handbag fusion part, 10; Square bottom fusion part, 11; Side edge fusion part, 1
2; Unnecessary film.

Claims (1)

[Claims] 1. In the bag-making process in which a long tube-like film or a half-folded strip-like film, which is the raw material for the bag body part, is continuously fed out and the film is fused for each width of the bag body, the film is A gusset fold is provided at the part corresponding to the bottom of the original bag,
Insert a plate between the folds of the gusset and press a wedge-shaped hot blade for each width of the bag from the front and back sides of the plate, At the same time, the film is fused together, and the wedge-shaped portion of the film is cut off. A linear hot blade is pressed against the original film for each width of the bag, and the film is fused and cut. A method for manufacturing a square bottom of a plastic film bag characterized by forming a square bottom.