JPS5855764B2 - Method of manufacturing shoes with injection molded foam soles - Google Patents

Description

[Detailed Description of the Invention] In the present invention, despite the existence of a constricted portion of the constriction that is raised on the bottom side due to the suspension of the constriction on the last, there is no adverse effect of the raised constriction. The present invention relates to a method of manufacturing a shoe having an injection-molded foam sole, which is formed by injection-foaming the sole integrally with the shoe cover, thereby making it possible to reduce the weight of the sole.

Conventionally, the lace cover used when integrally injection molded with the sole is a california bag made by sewing together the lower periphery of the lace and the periphery of the middle sole with their seam allowances protruding like palms. A number of loops made of thread are provided on the lower periphery of the ceremonial cover and the lower periphery of the cover, and a hanging string is inserted into these loops.
IJing-type jackets are known, but when they are used in injection foam molding in which the bottom is foamed for the purpose of reducing the weight of the bottom, there are the following disadvantages.

In other words, the foamable synthetic resin molding material that is injected and filled into the molding cavity formed at the bottom of the shoe by combining the foot mold, bottom mold, and side mold into which the shoe is suspended expands its volume by foaming. Therefore, the molding gap is usually designed to have a large volume by lowering the bottom mold below the position at the time of injection.

In order to make this bottom as lightweight as possible, it is best to keep the bottom mold as close as possible to the mold cover located above it so that the amount of injection filling is small, and to reduce the volume of the initial molding gap. That's why.

However, - these jackets can be used within this small-volume molding cavity to remove the constrictions of the jacket, the seam allowances in the case of California style jackets, and the loops and slings in the case of string jackets. Because the string is raised from the bottom of the last to the bottom side, there is a limit to how close the bottom last can be to the foot cover. , when brought close to almost touching each other,
The flow of the molding material injected into the molding cavity is inhibited by the raised constriction part, resulting in insufficient filling to every corner of the molding cavity, and voids and flow scars are formed on the molded bottom. In addition, even if a flow gap for the molding material is barely secured between the bottom mold and the raised constriction part, if the bottom mold is lowered after filling and foaming is performed, the foaming may occur, especially in the constriction part. There was a problem that caused a depression-like dent in the area where the bottom was removed.

To avoid this problem, the bottom mold had to be positioned a considerable distance from the raised constriction to define the molding cavity for injection.

In addition, since the constriction part itself is already raised, it is more difficult to configure the molding gap to have a small enough volume to obtain the desired lightweight sole.

The present invention solves the above-mentioned drawbacks of the conventional art, and will be explained in detail with reference to the drawings. A shoe cover 2 is hung on a last 1, and this hanging causes a constriction part 3 of the shoe cover 2 to be attached to the last 1. A molding cavity 7 is formed by fitting a bottom mold 5 and a side mold 6 to the lower part of the cover 2, and the molding of the bottom mold 5 is performed within the molding cavity 7. The surface 8 has a smaller area than the area 9 surrounding the narrowing part 3 and is located immediately below the area 9 and facing the area 9, and the molding surface 10 of the side mold 6 is a rising bottom side molding surface 10a. and a bottom side molding surface 10b, and a foamable synthetic resin molding material 1 is placed in the molding cavity 7.
1 is injected and filled, and then the bottom mold 5 is moved downward, its molding surface 8 is separated from the region 9 surrounding the narrowed part 3 to increase the volume of the molding cavity 7, and foaming is carried out in this molding cavity 7. filling the molding material 11 with foaming pressure,
The present invention relates to a method of manufacturing shoes having an injection-molded foam sole, which is characterized in that a foamed sole 12 is integrally molded with a shoe cover 2.

In the present invention, it is preferable that the head cover 2 is a widely used California type head cover or a string type head cover, but is not limited thereto.
When the shoe is hung in a shoe, the constriction portion 3 in the shape of a protuberance of the shoelace 2 is arranged on the periphery of the bottom surface 4 of the last 1.

For example, in the case of a California-style lace-up cover, this narrowing part 3 corresponds to a seam allowance that is made by sewing the lower periphery of the lace-up part 2a and the periphery of the insole 2b in a clasp shape or the like and protrudes toward the bottom side. In the case of a jacket, the constriction part 3 is a part consisting of a large number of loops made of thread on the lower periphery of the jacket and a hanging string inserted through the loops.

The bottom mold 5 is fitted into a side mold 6 which is divided into two or more parts in a split mold type, and a foot mold 1 in which the foot cover 2 is suspended, thereby forming a molding cavity 7.

The bottom mold 5 is designed to move vertically by sliding or the like while fitting into the side mold 6.

The molding gap 7 at the time when the foamable synthetic resin molding material 11 is injected is such that the bottom mold 5 has the mold surface 8 in the area 9 surrounded by the constriction part 3 of the foot cover 2 suspended from the foot mold 1. It is configured in a small volume located directly below.

Since the molding surface 8 of this bottom mold 5 has a smaller area than the area 9, the molding surface 8 comes into contact with the constriction part 3 despite the existence of the raised constriction part 3 surrounding the area 9. The close distance of the region 9 without causing any
They can be placed close to each other at about rL/rrL.

Raised constriction part 3 on the foot cover 2 suspended on the last 1
Normally, the position of the cover 2 is slightly different depending on how it is cut, how it is sewn, how it is hung, etc. The outer edge 13 of the molding surface 8 of the bottom mold 5 is set at 4 to 57 r/min from the position of the narrowing part 3 according to the general design, assuming that the narrowing part 3 may vary in position.
It is preferable to move it toward the inside by about 'rrL.

However, if the accuracy of setting the position of the hanging part 3 at a fixed position increases, it is possible to bring the outer edge 13 of the molding surface 8 closer to the position of the narrowing part 3.

It is preferable that the side mold 6 is of a split type that can be divided by movement such as lateral sliding.

The side mold 6 consists of a rising bottom circumference side molding surface 10a and a fitting grounding side forming surface 10b, and the fitting grounding side forming surface 10b is as follows:
When the bottom mold 5 moves downward to form a large volume due to foaming of the molding material 11 injected into the molding cavity 7, it cooperates with its molding surface 8 to expand the molding surface on the ground side of the bottom 12. Configure.

In the present invention, the molding surface 8 of the bottom mold 5 that has moved downward and the fitting-contact-side molding surface 10b of the side mold 6 are connected in series and matched in height to form the ground-contact molding surface of the bottom 12. Although the lowered position of the bottom mold 5 may be positioned as shown in FIG. The lowering position of the bottom mold 5 may be set at .

The foamable synthetic resin molding material 11 may be of any material as long as it can be injection molded and is suitable as a shoe sole material, such as polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer resin, polyethylene resin. , thermoplastic rubber, etc., or a mixture of these resins, and is mixed with a suitable foaming agent to make it foamable.

As the foaming agent, for example, when a polyvinyl chloride resin is used as the foamable synthetic resin molding material 11, an azodicarbonamide-based foaming agent such as the product name "Uniform AZ-HJ" (manufactured by Ohita Chemical Co., Ltd.) There are formulation examples that use blowing agents.

In the present invention, even if the constricted part of the shoelace suspended in the foot mold has a raised structure on the side to which the sole is attached, the molding surface of the sole mold has a smaller area than the area surrounded by this constricted part. Since the molding surface is opposed to that region, the flow of the molding material is not inhibited even if this molding surface is brought close to the lower part of the sleeve, so the molding gap at the time of injection can be configured to have a small volume. Therefore, the amount of molding material can be reduced, the sole to be molded can be made lightweight, and shoes that are comfortable to wear can be provided, and materials can be saved and costs can be reduced.

Furthermore, since the degree of foaming can be increased, a bottom with good cushioning properties can be formed.

In addition, despite the presence of the protruding constricted portion, this does not impede the flow of the molding material, so the inconvenience of forming voids and flow scars due to poor flow due to the constricted portion is eliminated. Ru.

Next, examples will be shown.

〔Example〕

A California-style shoe cover made of cotton woven fabric and an insole are sewn together in a bag-like manner around their peripheries, with the palm-shaped protruding seam allowance protruding toward the side where the sole will be glued. Hang it in close contact with the

Due to this suspension, the seam allowance protrudes at a height of approximately 2.5% from the bottom periphery of the last to the side to which the sole is attached.

A side mold and a bottom mold, which are divided in the toe and heel directions, are fitted into this to form a molding cavity.

When fitted, the molding surface of the bottom mold has a smaller area than the area surrounded by the protruding seam allowance, and is fixed facing that area.

The distance between the surface of the seam allowance on the area side and the outer edge of the molding surface of the bottom mold is about 57rL//lrL.

Further, the gap between the molding surface of the sole mold and the surface of the midsole to which the sole is bonded is approximately 2'r''//frL.

A compound mainly composed of polyvinyl chloride resin and containing azodicarbonamide as a foaming agent is injected into the molding cavity as a foamable synthetic resin molding material.

This allows the compound to fill the molding voids to the smallest detail.

Since the compound is heated to about 180° C. at the time of injection, it has already begun to foam slightly just before being press-fitted, and once it is press-fitted, it begins to foam in earnest within the molding cavity.

At this time, the bottom mold is moved downward and lowered to a preset position, but in this example, the molding surface of the bottom mold is aligned with the bottom molding surface of the side mold in a series. Slide it down to the desired position and adjust the molding gap to a large volume.

The foamed molding material then fills this large-volume molding cavity to every corner, and the bottom is molded.

The bottom is well adhered to the lower part of the cover at the same time as it is molded.

In this example, the molding surface of the bottom mold faces the inside area of the protruding seam allowance, and the area is smaller than this, so even if the molding surface is brought close to the midsole, the molding surface during injection The flow of the material is not inhibited and fills the molding void, and this small volume of molding material expands due to foaming, making it possible to mold a sole that is lightweight compared to the thickness of the sole, and the protruding seam allowance is A suitable bottom could be molded firmly and integrally with the cover without being exposed from the bottom.

[Brief explanation of the drawing]

1 and 2 are cross-sectional explanatory diagrams showing two steps of shoe manufacturing in one embodiment of the present invention using California shoelaces, and FIG. 1 is a pre-process of FIG. FIG. 2 shows a state in which the molding cavity is configured to have a large volume and the molding material is foamed. 1... Footprint, 2... Clothes, 3...
...Narrowing section, 4...Bottom, 5...
Bottom mold, 6... Side mold, 7... Molding cavity,
8... Molding surface of bottom mold, 9... Area, 1
0... Molding surface of side mold, 11... Molding material, 12... Bottom.

Claims (1)

[Claims] 1. A shoelace is hung on a last, and by this hanging, a constricted part of the shoelace is arranged in a raised shape on the bottom periphery of the last, and a bottom mold and a side mold are attached to the lower part of the shoelace. are fitted together to form a molding cavity, and the molding surface of the bottom mold in the molding cavity has a smaller area than the area surrounding the narrowed part, and is located immediately below the area and facing the area; The molding surface of the side mold consists of a rising bottom peripheral molding surface and a bottom contacting surface, and the foamable synthetic resin molding material is injected into the molding gap, and then the bottom mold is moved downward. The molding surface is separated from the area surrounding the constriction part to make the molding gap large in volume, and the molding gap is filled with the foamed molding material by foaming pressure, and the foamed bottom is molded integrally with the cover. A method of manufacturing shoes having an injection molded foam sole, characterized in that: 2. It is a California-style jacket formed by sewing together the lower periphery of the lace and the periphery of the midsole to form a bag-like structure, and the raised constriction part consists of a sewn seam allowance as described in claim 1. shoe manufacturing method. 3. It is a string-type jacket with a number of loops made of thread on the lower periphery, and a hanging string is inserted into the loops, and a raised constriction part is inserted between the loops and the loops. A method for manufacturing shoes according to claim 1, which comprises a hanging string.