JPH04126214A - Mold - Google Patents

Abstract

PURPOSE:To make it possible to fill molding material in respective cavities at the same filling speed by selecting orifices with optimum diameter by a method wherein orifices having different diameter are changeably provided in manifolds, which connect tire runners of a multiple cavity mold for a large number of products different in shape and its respective cavities. CONSTITUTION:In a manifold 14, which forms runners 10 and 12 connecting a sprue 4 and tire gates 6a and 8a of two cavities 6 and 8, two orifices 20 and 22 are changeably provided so as to control the flow rate of the runners 10 and 12. At use, a large number of orifices having different diameter are prepared so as to changeably fix in the manifold 14 in order to repeat trial injection by changing the orifice for the selection and determination of the orifice having optimum diameter. At this time, an orifice inserting hole 24 is provided in the flow path (on the runner 12 side) of the manifold 14. The optimum orifice 22 is inserted in the inserting hole 24 so as to fall in line with the flow path of the manifold 14 and then fixed with a machine screw 26.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mold for plastic injection molding, and particularly to an assembly mold for molding a large number of irregularly shaped products.

(Prior art) In an assembly mold that takes a large number of irregularly shaped products, the capacity and shape of the cavities are different for each product, so the filling speed of the material filled into each cavity during injection is different. Each product may have cracks or defects due to insufficient filling.

(Problem to be solved by the invention) This problem is particularly serious in the molding of products that require high precision. needs to be done.

Therefore, in an assembly mold that takes a large number of such irregularly shaped products, in the flow path leading to the cavity,
Preferably, means are provided to control the flow rate of material so that each cavity is filled at an equal rate.

In particular, the pair of upper and lower cassette halves that make up the DAT and VH5 magnetic tape cassettes have different structures in detail, and when molding them with a multi-cavity mold, accurate filling control is required.

Therefore, the present invention provides a mold for assembling a large number of irregularly shaped products, in which a means for controlling the flow rate of material is provided in the flow path leading to the cavities so that the filling speed into each cavity is equal. The purpose is to provide molds.

(Means for Solving the Problems) The mold according to the present invention is characterized in that the manifold extending from the runner to each cavity is provided with exchangeable orifices having different diameters.

In other words, a large number of orifices with different inner diameters are prepared, these are exchangeably fixed to the manifold leading to each cavity, and by repeating test injections, the orifice with the optimum diameter for each manifold is selected and the filling rate is equal to each cavity. It is characterized by making it possible to fill the molding material with the molding material.

Preferably, the cross-sectional shape of the inner diameter portion of this orifice is such that the cross-sectional shape of the inner diameter portion draws an inwardly convex curve in a cross section that includes the axis, so that the material does not remain in this portion and flows easily.

(Operations and Effects) According to the mold according to the present invention, the manifold is provided with orifices of different diameters so that the orifices with different diameters can be exchanged, so by repeating test injection, the orifice with the optimum diameter for each manifold is selected and applied to each cavity. It can be ensured that the molding material is filled at equal filling speeds.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of a two-cavity mold, with gates 6as 8a of two cavities 6.8 extending from sprue 4.
Manifold 14 forming runners 10.12 leading to
, two orifices 20.22 are replaceably provided to control the flow rate of each runner 1O112. In this example, each of the two runners 10.12 is provided with an orifice 20.22;
In the case of individual pieces, it may be provided only on one side.

The details of the part where the orifice is provided, which is the main part of the present invention, are shown in FIG. 2 for one side (orifice 22).

An orifice insertion hole 24 is provided in the flow M (runner 12 side) of the manifold 14, and an optimal orifice 22 is selected from among a large number of orifices that have a constant outer shape and differ only in orifice size and is inserted into this insertion hole 24 in the manifold. 1
4, and fix the orifice 22 in this hole 24 with screws 2B.

A thread is formed in the threaded portion 28 of this screw 26, and by removing this screw 2B, the orifice 22 can be replaced. Even if the orifice diameter of the orifice 22 changes, the cylindrical outer shape (outer diameter and thickness) remains constant as shown in Figures 3as 3bs 4as 4b, and even if the orifice is replaced, the orifice (inner diameter) remains the same. It always coincides with the flow path of the manifold 14.

As shown in the perspective views of these 3as 3bs 4as 4b and 5, the orifice 22a122b
The inner diameter portion of the tube has a cross-sectional shape that is convex inward in a cross section that includes the central axis, allowing the material to flow smoothly.

When in use, a large number of orifices with different inner diameters are prepared, these are exchangeably fixed to the manifold 14, and the orifice with the optimum diameter is selected and determined by repeating test injections with different orifices, and the orifice with the optimum diameter is selected and determined. 1
Fixed at 4.

Note that the shape of the orifice is not limited to a cylindrical shape, and various shapes such as a rectangular parallelepiped can be used.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an example of a two-cavity mold according to the present invention, Fig. 2 is an enlarged cross-sectional view of the main parts thereof, and Fig. 3a is a cross-sectional view showing an example of an orifice used in the present invention. , FIG. 3b is a plan view thereof, FIG. 4a is a sectional view showing the other side of the orifice used in the present invention having a different diameter, FIG. 4b is a plan view thereof, and FIG. 5 is a perspective view of the orifice. 2...Mold 4...Sprue 6.8...Cavity 6a, 8a...Gate 10.12...Runner 14...Manifold 22...Orifice Figure 30 Figure 3b Figure 40 Figure 4b Figure December 1990 Date of 1990 Patent Application No. 246 Name of the invention Relationship to the case of the person making the mold amendment

Claims (1)

[Claims] In assembly molds that produce a large number of irregularly shaped products,
A mold characterized by interchangeably providing orifices with different diameters on the manifold from the runner to each cavity.