JPH0379317A - Plastic molded product - Google Patents

Abstract

PURPOSE:To manufacture a product of good molding properties and dimension accuracy by making small section areas of bonding sections with resin constituted parts of runner sections and adjusting the molding pressure. CONSTITUTION:Resin constituted parts 3a and 3b and a gate 6 are connected together by belt-shaped runners 7a and 7b formed respectively and integrally with a base 2. The molded parts 3a and 3b are of almost same shape and dimension and the distance between the resin molded part 3a and the gate 6 is longer than that of 3b and the gate, and the section area of a bonding section 7c with the resin molded part 3a of the runner 7b is lower than those of other sections of the runner 7b. The pressure difference between the runner 7a and the runner 7b generated at the time of resin injection, therefore, can be equalized by setting the section area of the bonding section 7c properly. A plastic molded product of good molding properties and dimension accuracy can be manufactured by said arrangement.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a composite molded product made of plastic and a substrate, and particularly relates to a composite molded product made of plastic and a substrate, and in particular, to a composite molded product made of plastic and a substrate, and in particular, to a composite molded product made of plastic and a substrate. This product relates to plastic molded products by outsert molding.

(Prior Art) Outsert molding, in which a through hole is formed in the substrate and the resin components are integrally molded onto the substrate by penetrating the through hole, is widely used as a means for fixing a plurality of resin components to a substrate. ing. In this case, a runner that connects the resin injection part (hereinafter referred to as a gate) formed on the board and the resin component is integrally molded on the board, but according to conventional molding technology, the distance from the gate to the resin component is The difference in molding pressure was large depending on the length of the resin, and the difference in molding shrinkage rate of the resin was also large.

For this reason, there is a problem in that an error occurs in the molding shrinkage rate estimated at the time of mold design, and a dimensional error occurs in the resin molded part. Further, the required strength of the side walls of the cavity and the substrate through-hole near the gate is significantly different from the required strength of those located far from the gate. Furthermore, molded resin parts close to the gate tend to have poor mold release, and molded resin parts located far away tend to be insufficiently filled.

(Problems to be Solved by the Invention) As mentioned above, in plastic molded products by conventional outsert molding, differences in molding pressure and molding shrinkage rate are large depending on the distance from the gate, resulting in poor dimensional accuracy of the molded product,
There has been a problem in that the side walls of the through holes formed in the substrate lack strength, or mold release failures or filling shortages tend to occur.

The present invention has been made in view of these points, and an object of the present invention is to provide a plastic molded product having good moldability and dimensional accuracy.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a substrate having a plurality of through holes, and a molded substrate that protrudes from the surface of the substrate and passes through the through holes. In a plastic molded product consisting of a resin component and a runner portion that is integrally molded on the substrate and connects the resin component and the resin injection port, the joint portion of the runner portion with the resin component is referred to as the runner portion. The cross-sectional area of the other parts is smaller than that of other parts.

(Function) According to the above configuration, the molding pressure can be lowered by reducing the cross-sectional area of the runner in a portion where the molding pressure is desired to be lowered, such as a resin component near the gate. As a result, the molding pressure difference between resin components having different distances from the gate can be reduced, and moldability and dimensional accuracy can be improved.

(Example) Hereinafter, an example of the plastic molded product according to the present invention will be described with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 and 2. FIG.

This molded product 1 has a substrate 2 formed of a metal plate sandwiched between a pair of upper and lower molds, and a resin component 3 integrally fixed to the substrate 2 by outsert molding.

A plurality of, for example, two, through holes 4 are formed at predetermined locations on the substrate 2, corresponding to the resin component parts, and the cylindrical resin components 3a, 3a, and 3a are inserted through these through holes 4, respectively.
3b is integrally molded with the substrate 2. Further, a through hole 5 is formed in the substrate 2, and a cylindrical gate 6 penetrating through the through hole 5 and forming a resin injection port is integrally molded with the substrate 2. The resin components 3a, 3b and the gate 6 are connected by band-shaped runners 7a, 7b integrally formed on the substrate 2, respectively.

At this time, the resin molded parts 3a and 3b have substantially the same shape and size, and the distance between the resin molded parts 3a and the gate 6 is longer. Also, the resin molded part 3 of the runner 7b
The cross-sectional area of the joint portion 7c with the runner 7a is smaller than that of other portions of the runner 7b.

Next, the operation of this embodiment will be explained. When performing outsert molding by injecting resin from the gate on the mold side, runner 7
Since the runner 7b is shorter than the runner a, the flow length of the resin is short, and the pressure difference between the vicinity of the gate 6 and the vicinity of the joint 7c with the resin component 3b is relatively small. On the other hand, long runner 7
At point a, the pressure difference becomes large. However, since the cross-sectional area of the joint 7c is smaller than other parts of the runner 7, the pressure difference becomes large, and by appropriately setting the cross-sectional area of the joint 7C, it becomes equal to the pressure difference on the runner 7a side. can do. That is, the molding pressure can be made uniform.

According to this example, the molding pressure can be made uniform, which improves the dimensional accuracy of the molded product, prevents damage to the side walls of through holes in substrates with low strength, and prevents defective mold release and insufficient filling. Occurrence can also be prevented.

In the above embodiment, a case has been described in which the difference in molding pressure due to the difference in length of the runners 7a and 7b is reduced, but it can also be applied to the case where parts of the mold with low strength are partially protected due to product design. . Furthermore, it goes without saying that the number of resin components 3 is not limited to two.

[Effects of the Invention] As explained above, according to the present invention, the cross-sectional area of the joint portion of the runner portion with the resin component during outsert molding is made small to adjust the molding pressure. A plastic molded product having good moldability and dimensional accuracy can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view. 1... Molded product 2... Substrate 3... Resin component 4... Through hole 6... Gate (resin injection port) 7... Runner 7C... Joint part No.

Claims (1)

[Claims] A substrate having a plurality of through holes, a resin component that protrudes from the surface of the substrate and is molded to pass through the through holes, and a runner that is integrally molded on the substrate and connects the resin component and a resin injection port. 1. A plastic molded product comprising: a joint portion of the runner portion with the resin component;