JPH04307217A - Mold for insert molding - Google Patents

Abstract

PURPOSE:To improve the accuracy of axial-direction positional size, etc., in an injection cavity at the time of the closing of a mold for injection molding in an insert member buried into the main body of an injection molded piece. CONSTITUTION:A nut 4 as an insert member is supported by a holding pin 5, etc., in an injection cavity 3 from the moving mold 2 of a mold for injection molding while a pushing pin 6 as a pushing means for pushing the top section of the nut 4 against the cavity surface 3b of said moving mold 2 from the stationary mold 1 side and a compression coil spring 7 are installed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to improving the accuracy of the position of an insert member in a mold for insert molding.

0002

[Prior Art] When insert members such as nuts and pins are embedded in the main body of a synthetic resin injection molded product,
This insert member is placed in advance at a predetermined position within the cavity of the injection mold. FIGS. 3(a) and 3(b) are cross-sectional explanatory views of essential parts of one example. (a) is its exploded view, (
b) shows when the mold is closed.

Reference numeral 1 denotes a fixed mold, 2 a movable mold, 3 an injection cavity formed between the molds 1 and 2 when the molds are closed, and 3a the respective cavity surfaces. Reference numeral 4 denotes a nut as an insert member, and injection is performed while it is fitted onto and held on a holding pin 5 supported from the movable mold side.

0004

[Problem to be solved by the invention] However, Fig. 3 (
The position of the nut 4 in the cavity 3 shown in b) has a fitting clearance c1 with the holding pin 5, and an axial clearance (play) c1, c2 with both cavity surfaces (both dimensions are exaggerated). Due to these factors, the axial position of the nut 4 and the perpendicularity of both sides of the nut relative to the central axis vary within the range of the backlash dimension, resulting in the problem that correct axial dimensions and perpendicularity cannot be obtained. there were.

The present invention has been made in view of the above-mentioned circumstances, and improves the accuracy of the axial position and perpendicularity of the insert member without requiring particularly high dimensional accuracy in relation to the position of the insert member held within the cavity. The purpose is to provide the means to do so.

[0006]

[Means for Solving the Problems] Therefore, in the present invention, the insert member embedded in the main body of the injection molded product is placed on either the movable mold side or the fixed mold side of the injection mold. A press for supporting the insert member in the injection cavity from one side and pressing the top part of the insert member against the cavity surface of one of the movable mold and the fixed mold from the other side of the movable mold and the fixed mold. The above object is achieved by configuring the device to include means.

[0007]

[Operation] With the above structure, when the mold is closed, the top of the insert member is pressed against the cavity surface of one of the movable mold and the fixed mold using a pressing means such as a spring or a hydraulic cylinder. , since the opposite end surface of this insert member contacts the cavity surface without any gap,
Its axial position becomes constant, and the accuracy of verticality is also ensured.

[0008]

EXAMPLES The present invention will be explained below based on examples. FIG. 1 shows a cross-sectional view of the main part (corresponding to FIG. 3(b) of the conventional example) when the mold is closed, which is equipped with an embodiment of the insert member pressing means according to the present invention, and is the same as that in FIG.
Components (equivalent) are represented by the same reference numerals, and duplicate explanations will be omitted. (Structure) Reference numeral 6 denotes a press pin which is slidably inserted in the axial direction through the inner diameter part bored into the cavity surface 3a on the side of the fixed mold 1, and its head is on the side of the fixed mold 1. back part 1
When the mold is closed, a compression coil spring 7 made of steel is inserted between the mold and the mold, and the top of the nut 4 is pushed in the direction of the arrow shown in the figure, and the opposite surface is brought into contact with the cavity surface 3b of the movable mold. It is configured to be in contact with

(Function) For this reason, when the mold is closed, the nut 4
Since its axial position and verticality are accurately regulated within the cavity 3, the precision of the molded product that is injected in this state is improved. FIG. 2(a) shows a cross-sectional explanatory diagram of the axial positional dimension A of the nut 4 portion of the molded product Pa and the accuracy improving part of the perpendicularity. (Other Embodiments) In the above embodiments, an example was explained in which the insert member was held in a movable mold and pressed by a fixed mold, but conversely, the insert member was held in a fixed mold, It may be pressed by a moving mold. Furthermore, although this embodiment has been described with reference to a case in which the insert member is a nut 4, the principles of the present invention are not limited to this only, and the same effect can be obtained by applying it to other cases such as pin-shaped members, for example. Of course, Figure 2
In (b) and (c), the axial height dimension B or C of the pin-shaped member 8 or 9 relative to the molded product Pb or Pc, respectively.
Two examples of improved accuracy are shown below. The direction in which each insert member is pressed is indicated by an arrow.

0010

[Effects of the Invention] As explained above, according to the present invention, when the mold is closed, the top of the insert member is pressed to bring the opposite end surface into contact with the cavity surface of the movable mold or the fixed mold. As a result, the accuracy of the axial position and perpendicularity of the insert member is improved.

[Brief explanation of drawings]

[Fig. 1] Cross-sectional explanatory diagram of the main part when the mold is closed, equipped with an embodiment of the insert member pressing means

[Figure 2] Explanatory diagrams of three examples of improving the axial position accuracy of insert members

[Figure 3] Cross-sectional view explaining the position of the insert member in the cavity of a conventional molding die

[Explanation of symbols]

Pa, Pb, Pc Injection molded product 1/2 Fixed/moving mold 3 Cavity 3a, 3b Cavity surface 4 Nut (insert member) 5 Holding pin 6 Press pin (pressing means) 7 Compression coil spring (pressing means)

Claims (1)

[Claims] 1. An insert member embedded in the main body of the injection molded product is supported in the injection cavity from either the movable mold side or the fixed mold side of the injection mold, and For insert molding, characterized in that a pressing means is provided for pressing the top of the insert member against the cavity surface of one of the movable mold and the fixed mold from the other of the movable mold side and the fixed mold side. Mold.