JPH0226501A - Injection molding for boot - Google Patents

Abstract

PURPOSE:To mold a drum part with a satisfactory appearance without forming a shrinkage and a flow mark on a drum part surface by injection-filling a drum part molding cavity with a drum part molding material from a gate opened in the lower periphery part of the drum part molding cavity and molding the drum part. CONSTITUTION:The drum part molding material is made to fill a drum part molding cavity 1 from a gate 2 opened in the lower periphery part of the drum part molding cavity 1, and a drum part 3 is molded. As a result, a drum part molding material fluidity in the drum part molding cavity 1 is satisfactory, an injecting pressure cannot be lowered even in an upper edge (a) of the cavity 1 and in the front part of the cavity 1 having a complex curved surface structure, a dispersion cannot be generated to the fluidity of the drum part molding material, the shrinkage, flow mark and chip cannot be generated onto the drum part surface of the rubber boot to be molded as a conventional case, and the boot having the drum part with the satisfactory appearance can be molded.

Description

[Detailed description of the invention] (Industrial application field) This invention relates to an injection molding method for boots.

(Prior Art) Conventionally, as published in Collection of Well-known and Commonly Used Techniques for Shoe Manufacturing 165.166 published by the Japan Patent Office dated January 31, 1980, the lower side of the last (male mold), i.e. The injection molding method for boots is generally known in which a boot is formed by injecting and filling a torso molding material into a torso molding cavity through a gate opening at the lower surface of the midsole molding cavity. However, the torso molding cavity has a more complex shape, a narrower gap, and a larger surface area than the midsole molding cavity C and the sole molding cavity, corresponding to the torso of the boots to be molded. When the body molding material is injected and filled from the gate opening on the lower surface of the bottom molding cavity through the midsole molding cavity and into the body molding cavity rising almost vertically from the midsole molding cavity C, the body molding material located far from the gate is injected and filled. In the upper end a of the cavity and the front part of the torso molding cavity which has a complicated curved surface structure, the injection pressure is lowered and the fluidity of the torso molding material varies, causing the upper part of the boot molded in this way to had the disadvantage that sink marks, flow marks, and chips were formed on its surface, which significantly deteriorated its appearance.

(Problems to be solved by the invention) This invention prevents sink marks and flow marks on the surface of the body.

It is an object of the present invention to provide boots that are free from chips and have a good-looking upper part.

(Means for solving interlayer points, embodiments) The present invention will be explained below with reference to the drawings showing the state of implementation of the present invention.The present invention will be explained below with reference to the drawings showing the state of implementation of the present invention. The gist of the invention is an injection molding method for boots, which is characterized in that the upper part 3 is formed by injecting and filling the upper part molding cavity 1 with the following.

In this invention, the body molding cavity 1 is formed by a side mold 11.11, a bottom mold 12 and a last 13.

In this invention, the gate 2 is opened at the lower side of the body molding cavity 1 at the outer periphery 121 of the bottom mold as shown in FIG. 1 or at the lower side 111 of the side mold as shown in FIG. In this invention, if the opening direction of the gate 2 is directed toward the upper side of the body molding cavity 1, the fluidity of the body molding material in the body molding cavity 1 can be further promoted, and the quality can be further improved. You can get stable boots. If a plurality of gates 2゜2... are opened at opposing positions of the shoulder molding cavity 1 via the last 13 or the middle bottom molding cavity C, the body molding cavity 1 can be opened during Wi4 injection molding.
The body molding material can be simultaneously injected and filled into the body molding cavity 1 through the gates 2, 2, etc. from opposite positions of the body molding cavity 1. Even when supported in the body molding cavity 1 in a suspended state, the last 13 will not be deflected by the injection pressure of the body molding material from one direction, and the gap between the body molding cavity 1 can be maintained at a constant width. The body part 3 with stable wall thickness can be injection molded.

Furthermore, if necessary, the last 13 forming the body molding cavity 1 can be covered with a lining cloth (not shown) made of stretchable cloth such as stockinette, so that the lining can be applied to the body 3 at the same time as the injection molding of the body 3. This is convenient because the cloth can be glued together. In this invention, the body molding material to be injected and filled into the 5M molding cavity 1 includes vinyl chloride resin, ethylene, vinyl acetate copolymer, polyurethane resin, 1.2 polybutadiene rubber, styrene-butadiene block copolymer, etc. Examples include thermoplastic rubber. These resins or rubbers are injected and filled into the body molding cavity 1 through the gate 2 to form the body 3, using a conventional method.
If the grounding sole 4 is formed on the surface in advance, it is convenient because the trunk 3 can be integrally welded to the grounding sole 4 at the time of molding the trunk 3.

(Effects of the Invention) As described above, the present invention injects and fills the body molding material directly into the body molding cavity 1 through the gate 2 opened at the lower side of the body molding cavity 1. The fluidity of the body molding material at
There is no variation in the fluidity of the torso molding material, and there are no sink marks, flow marks, or chips on the torso surface of the boots that are molded, and the boots have a good-looking torso. Can be molded.

[Brief explanation of the drawing]

The drawings are sectional views of essential parts showing the state of injection molding of the boots of the present invention, and FIG. 1 shows the first embodiment, and FIG. 2 shows the second embodiment. 1゜2゜4゜a. Body molding bottom part 1... Outer periphery gate ground bottom body part molding case code description Bitty 11... Side mold 12... Bottom mold 13... Last 3, upper end of shoulder bitty b Front part of body molding cavity C6 middle bottom molding cavity

Claims (1)

[Claims] An injection molding method for boots, characterized in that a torso molding material is injected and filled into a torso molding cavity 1 through a gate 2 opened at the lower side of the torso molding cavity 1 to mold a torso 3.