JPS6252561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing injection molded shoes having a shoe-like or sock-like lining fabric having an insole portion, and in which residual gas such as air is discharged from a closed mold during molding. The object of the present invention is to provide a method that eliminates the adverse effects of residual gas on molded products and can produce injection molded shoes with high commercial value.

Conventionally, when injection molding shoes using non-foaming injection molding materials, air is often forced into the mold when the molding material is injected, but the inner sole of the sock-like lining fabric or the inner sole of the shoe If the mold is made of a breathable material such as a piece of cloth, even if the mold is closed, the trapped air can be dissipated from the breathable midsole to the outside air. However, in order to bond the molded outsole and the insole more firmly, adhesive may be applied to the surface of the insole that will adhere to the outsole, or adhesive may be used to make the insole stronger. If a material made by pasting two pieces of cloth is used, there is no air permeability in the inner bottom part, and the mold is sealed, so there is no way for air to escape, and this air will be absorbed by the flow of the injected resin. There is an inconvenience that this fluid trajectory forms flow pattern scratches on the surface of the molded product, which are generally referred to as "flash marks" in the industry.
Alternatively, air may remain at the bonding interface between the inner sole of the sock-like lining fabric or the inner sole of the shoe cover and the molded body, resulting in poor adhesion between the inner sole and the molded body in the area where this air exists, causing the inner sole of that area to catch fire. Not only do these shoes have an unsightly bulge-like shape, but the blister-like bulges tear due to poor adhesion while the shoes are being worn, making them difficult to wear.

The present invention provides a method for manufacturing injection molded shoes that eliminates the conventional drawbacks as described above. 3, a sleeve 5 or a sock-like lining 5' having an inner sole 4 made of non-breathable material
At the same time, the needle-like protrusion 2 covers the middle bottom part 4.
The outer mold 7 is assembled with the last 3 to form a molding cavity 9 including the outsole molding cavity 8, and the needle-like protrusion 2 is inserted into the thick part of the outsole molding cavity 8. Last 3 without reaching the intermediate position
The method of manufacturing injection molded shoes is characterized in that the non-foaming injection molding material 10 is injected and press-fitted into the molding gap 9 so as to protrude from the bottom surface 1 of the shoe.

The non-expandable injection molding material 10 used in the present invention is a thermoplastic resin such as polyvinyl chloride, polyethylene, or a thermoplastic elastomer such as styrene-butadiene, polyurethane, or ethylene-vinyl acetate copolymer. There are polymeric substances and thermoplastic polymeric compounds that have polymeric substances as their main ingredients.

A mold into which the non-foaming injection molding material 10 is injected and press-fitted is composed of a last 3 and an outer mold 7, and the last 3 and the outer mold 7 are made of a metal material.

The injection molded shoes to be manufactured in the present invention are called short shoes or boots, and when manufacturing short shoes, generally a shoe cover 5 is attached to the last 3 as shown in FIG. This last 3 is combined with a side mold 7' as an outer mold 7 and a bottom mold 7'' to form a series of outsole molding gaps 8 and, if necessary, peripheral tape part molding gaps 8'.Meanwhile, the boots are manufactured. If a sock-like lining fabric 5' is to be applied to the last 3, an outer mold 7 is generally attached to the last 3, as shown in FIG.
By combining the side mold 7' and bottom mold 7'', a boot body molding cavity 8'' and an outsole molding cavity 8 are formed.
When these sleeves 5 and sock-like lining cloth 5' are attached to the last 3, they form an integrally provided inner sole 4 made of a non-breathable material.
(hereinafter simply referred to as the middle bottom 4) is the bottom 1 of the last 3.
A needle-shaped protrusion 2 protrudes from the inner part 4, and a hole 6 is formed in the inner bottom part 4.
can be opened. The above-mentioned side mold 7' is generally of the so-called split mold type, which is divided into two or more parts, whether in the manufacture of short shoes or boots. If necessary, a split mold can also be used for the bottom mold 7''.

The needle-like protrusion 2 protruding from the bottom surface 1 of the last 3 is
It may be one or more. The length of the needle-like projection 2 is
It is preferable that the tip 11 of the needle-like protrusion 2 exists in a range that does not reach the intermediate position of the thickness of the outsole forming gap 8 at the position on the bottom surface 1 of the last 3 where the needle-like protrusion 2 is installed. Preferably, the needle-like protrusion 2 is located at the midsole 4.
The length should be long enough to penetrate through. It is preferable that the tip 11 of the needle-like protrusion 2 is sharp so that it can easily penetrate the inner sole 4. The needle-like protrusion 2 has a conical shape, an elliptical conical shape, a triangular shape, etc., and its cross section is circular, elliptical, triangular, or polygonal such as a square or a star, as shown by a to e in FIG. 4, respectively. conical,
Or it has a polygonal pyramid shape such as a quadrangular pyramid shape, and
It is also possible to have a groove 12 extending in the length direction of the needle-like projection 2 on the conical side surface thereof. The shape of the groove 12 can be appropriately adopted such as a V-shape, a U-shape, a U-shape, or a trapezoid in cross section. If V-shaped grooves 12 are formed on each of the plurality of side surfaces of the polygonal pyramid-shaped needle-like protrusion 2, it can be made into a polygonal pyramid shape, such as a star-shaped cross section as shown in FIG. 4e, for example. These needle-like projections 2
may be made of the same metal as the last 3 and may be formed so as to protrude seamlessly from the bottom surface 1 during molding of the last 3, as shown in FIG. Or the first
Drill a hole in the bottom 1 of the last 3 as shown in the figure,
A needle-like protrusion 2 formed separately from the same or different metal as the last 3 may be connected to the bottom surface 1 by inserting its base into this hole.

The installation parts of the last 3 of the needle-like protrusions 2 on the bottom surface 1 may be scattered over the entire bottom surface 1 as shown in FIG.
As shown in the figure, it may be concentrated in a region that constitutes a particularly thick portion.

Hole 6 in midsole 4 formed by needle-like protrusion 2
Since the insole can be easily hidden by attaching or placing the insole on the surface of the insole 4, it can be constructed so as not to be unsightly.

In the present invention, the needle-like protrusion 2 protruding from the bottom surface 1 of the last 3 penetrates through the inner sole 4 of the lace cover 5 or sock-like lining cloth 5' attached to the last 3 and forms a hole 6.
Since the hole is opened, even if air is drawn in during injection molding, the air can escape from the hole 6 to the last 3 side of the inner bottom 4 and dissipate into the outside air, thereby forming flash marks on the molded product. Without a problem,
In addition, there is no air present at the bonding interface between the molded product such as the sole of a shoe and the shoe cover 5 or sock-like lining fabric 5' having the midsole 4, and the two can be well bonded. Since the air does not form a blister-like raised part at the joint interface, this part does not tear due to wear, and also comes into contact with the foot of the shoelace 5 and the sock-like lining fabric 5'. Since no raised part is formed on the side where the shoe is worn, the shoe is not unsightly and does not feel rugged, making the shoe comfortable to wear.

In addition, since a non-breathable material is used for the inner sole 4, an adhesive can be applied to the surface of the inner sole 4 that adheres to the outsole, thereby making the bond between the inner sole 4 and the outsole stronger. In addition, a laminated sheet made by bonding two or more pieces of fabric or sheet material together with an adhesive can be used as the material for the inner sole 4.
The midsole 4 can be made stronger, and the durability of the shoe can be increased.

Furthermore, by making the needle-like projections 2 penetrate the inner sole portion 4 and protrude into the outsole molding cavity 8, the non-foaming injection molding material 1 required for molding is equal to the volume of the needle-like projections 2.
By reducing the amount of 0 and saving materials, the product cost is reduced, and after molding, the part where the needle-like protrusion 2 was present becomes a void, which makes the shoe lighter and easier to wear. The voids provided can also provide cushioning properties as the sole of a shoe. In addition, since the needle-like protrusion 2 has a hole 6 in the inner sole part 4 and is exposed to the outsole molding cavity 8, the non-foaming injection molding material 10 that comes into contact with it is easily cooled.
The demolding of the molded body can be accelerated, the production cycle can be accelerated, mass production can be made possible, and the product cost can be reduced.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams showing examples of embodiments of the present invention, FIG. 3 is a partial perspective view of an example of the last heel, and FIGS. 4 a, b, c, d, and e are needles, respectively. A cross-sectional view of the protrusion is shown. 1... Bottom surface, 2... Needle-like projection, 3... Last,
4...Insole made of non-breathable material, 5...Flip cover, 5'...Sock-like lining fabric, 6...Hole, 7...Outer mold, 8...Outsole molding void, 9...Molding void,
10...Non-foaming injection molding material.

Claims (1)

[Scope of Claims] 1. A last having one or more needle-like protrusions protruding from the bottom thereof is covered with a sock-like lining fabric or a sock-like lining having an inner sole made of non-breathable material, and the needle-like protrusions are attached to the last. The inner sole is penetrated, and the outer mold is combined with the last to form a molding cavity including the outsole molding cavity, and the needle-shaped protrusion is inserted into the last within a range that does not reach the middle position of the thickness of the outsole molding cavity. protrude from the bottom,
A method for manufacturing injection molded shoes, which comprises injecting and press-fitting a non-expandable injection molding material into the molding gap. 2. The shoe manufacturing method according to claim 1, wherein a groove extending in the length direction of the needle-like projection is formed on a side surface of the needle-like projection.