METHOD FOR PRODUCING MULTI-LAYERED ARTICLES IN AN INJECTION-MOULDING PROCESS

Abstract

An injection-molding process for injecting a shoe soling including at least two adjacent injection-molding layers onto a shoe upper drawn over a shoe last, uses a mold cavity including a frame, the cavity being covered at the top by the upper also serving as a mold cover, with plastic material being injected into the cavity below the upper. To produce two adjacent injection-molding layers of plastic materials having different properties and reaction times in one operation, i.e. without needing an interim mold opening, before covering the cavity a film is clamped over it by a clamp mounted on the frame. When filling the cavity, the space below the film is first filled with plastic material to produce the first injection-molding layer and then, to produce the adjacent second injection-molding layer, the space above the film is filled with plastic material. Plastic materials are used that inseparably attach to the film.

Claims

1. Injection molding method for injecting a shoe soling comprising at least two adjacent injection molding layers onto a shoe upper drawn over a shoe last, using a mold cavity comprising a frame (1), said cavity being covered at the top end by the shoe upper also serving as a mold cover, wherein plastic material is injected into the mold cavity below the shoe upper, wherein prior to covering the mold cavity a film (6) is clamped over the mold cavity by a clamping device mounted on the frame of the mold cavity, wherein, when filling the mold cavity, the space below the film is first filled with plastic material to produce the first injection molding layer (4) and then, for the production of the adjacent second injection molding layer (5), the space above the film is filled with plastic material, wherein plastic materials are used that inseparably attach to the film.

2-4. (canceled)

5. Injection molding method according to claim 1, wherein a space for the production of the second injection molding layer (5) is kept open by means of a flow aid arranged underneath the mold cover (8) and above the film (6).

6. Injection molding method according to claim 1, wherein, before filling the mold cavity, the mold cover (8) is immersed by a short stroke into the mold cavity thereby tensioning the film (6) downwards, following which the plastic material of the first injection molding layer (4) is injected and attaches to the film (6), and afterwards by raising the mold cover to its normal position, a space (12) is created above the film (6) for injecting the plastic material of the adjacent second injection molding layer (5).

7-15. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention is elucidated in sufficient detail by way of the following figures, where

[0011] FIG. 1: is a longitudinal section of an injection mold on which a clamping device is mounted;

[0012] FIG. 2: is a cross-sectional view of an injection mold with mounted clamping device.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0013] FIG. 1 shows an injection mold with a frame 1 consisting of two lateral mold segments, which are moved against each other to form a mold cavity, and a base die 2. The figure shows a three-layer buildup of a shoe soling, consisting of an outsole 3 with an activated surface previously placed into the mold cavity, a midsole 4 (first injection molding layer) and an upper sole 5 (second injection molding layer). A clamping device 7 is placed on the frame 1, holding a film 6 which is spanned above the mold cavity. The plastic material of the midsole 4 (first injection molding layer) is injected into the mold cavity via a lower injection duct 10 above the outsole 3 and below the film 6. The plastic material of the upper sole 5 (second injection molding layer) is injected into the mold cavity via an upper injection duct 9 above film 6 and below a mold cover 8, which is formed by a shoe upper 11 mounted on a last.

[0014] In FIG. 2 it is illustrated how the mold cover 8 carries out a short downward stroke in such a way that it is in lowered position between the lateral mold segments of frame 1 with clamping device 7 fitted. This causes the last 8 (i.e. the mold cover) covered with the shoe upper 11 to push down the film 6 to a slight extent. When the plastic material of the midsole 4 (first injection molding layer) is injected between the film 6 and the outsole 3, said film 6 adheres to the plastic material of midsole 4 (first injection molding layer), so that after raising the mold cover 8 by the amount of the short stroke into its initial position, space 12 is created between the mold cover 8 and film 6. The plastic material forming the upper sole 5 (second injection molding layer) is injected into the space 12 thus created above the film 6, said plastic material produces the bond between film 6 and the mold cover 8 (i.e. the shoe upper 11 drawn over the last).