JPS6054846B2 - Production method of laminated resin molded products - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a method for producing laminated resin molded products such as operation buttons of tape recorders formed by molding in industrial fields of application. The objective is to obtain a method for producing molded products in which the boundaries between the laminated resins are uniform.

BACKGROUND OF THE INVENTION The structure of a conventional laminated resin molded product and its production method will be explained using the rewind button of a tape recorder as shown in FIGS. 1 to 6 as an example.
FIG. 2 shows the structure of the operation button, where 1 is a first resin molded body, 2 is a second resin molded body laminated on the top surface of this first resin molded body 1, and is of a different color from the first resin molded body 1. There are two resin molded bodies.

The first resin molded body 1 is provided with a recess 3 into which an operating member is press-fitted, and protrusions 5, 5 whose end faces form a rewind mode indicator mark 4 are provided at the center of the upper surface thereof. There is. The end surfaces of the protrusions 5, 5 are formed to match the upper surface of the second resin molded body 2, and
As shown in the figure, the end faces of the protrusions 5, 5 are exposed as a rewind' mode indicator mark 4 at the center of the upper surface of the second resin molded body 2. Next, FIGS. 3 and 4 show a mold for explaining the production method of the above-mentioned operation button.
In FIG. 3, reference numeral 6 indicates a first mold having a convex portion 7 for forming the recess 3 for press-fitting the operating member, and reference numeral 8 has a recess 9 for forming the outer surface of the first resin molded body 1. Second
It is a mold.

Then, the first and second molds are joined to each other as shown in FIG. If the space 10 formed between them is filled with resin, the first resin molded body 1 is formed. After forming the first resin molded body 1, as shown in FIG. 4, a recess 11 into which the first resin molded body 1 is inserted and which forms the outer surface of the second resin molded body 2 A third mold 12 having a shape is joined to the first mold 1. At this time, if the space 13 formed by the upper surface of the first resin molded body 1 and the recess 11 of the third mold 12 is filled with resin,
The second resin molded body 2 is integrally formed on the upper surface of the first resin molded body 1, and the operation button shown in FIGS. 1 and 2 is obtained. Problems to be Solved by the Invention According to the conventional method for producing a laminated resin molded article, the following drawbacks occur.

Firstly, the drawback of the above molded product production method is that when forming the second resin molded product 2 after forming the first resin molded product 1, the recess 11 of the third mold 12 is If the outer diameter of the resin molded body 1 is larger than that of the resin molded body 1, a gap will be created between the outer circumferential wall of the first resin molded body 1 and the recess 11 of the third mold, and the resin forming the second resin molded body will be The resin flows into the gap and appears as a burr 14 on the outer circumferential wall of the completed operation button as shown in FIG.

The end of the burr 14 forms a meandering curve, and the shape of this curve is different for each of the plurality of operation buttons, resulting in an unsightly appearance and significantly detracting from the commercial value of the operation button. 2. On the other hand, when forming the second resin molded body 2, the recess 11 of the third mold 12 is formed of the first resin molded body. When joining the third mold 12, which is smaller than the outer diameter of the feature 1, to the first mold 6, the peripheral portion between the third molds 12 is
As shown in FIG. 6, scratches 15 are formed on the upper end of the outer circumferential wall of the operation button that has come into contact with the upper surface periphery of the resin molded body 1, and scratches 16 are formed on the outer circumferential wall of the operation button. There were some shortcomings.

If the operation button is damaged, it has to be discarded as a defective item, which has become a big problem. In order to solve the problem caused by the dimensional difference between the third mold and the first resin molded body 1, it is necessary to In other words, the recess 11 of the third mold and the recess 9 of the second mold that forms the first resin molding should be made to have the same dimensions. Realizing this was extremely difficult in terms of mold processing, requiring a lot of time and a large amount of money.

j Means for Solving the Problems In order to solve the above problems, the production method of the present invention provides a protruding wall around the upper surface of the first resin molded body, and connects this protruding wall to the second resin molded body. The present invention is characterized in that resin filling for the second resin molded body is performed while the third mold is in contact with the inner circumferential wall of the recessed portion of the third mold.

Effects The present invention has the above-described structure, and when the second resin molded body is filled with resin, the protruding wall of the first resin molded body is in contact with the inner circumferential wall of the recess of the third mold. Since the dimensional difference between the first and second resin molded bodies is absorbed, burrs can be prevented from forming on the joint surfaces of the first and second resin molded bodies.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to FIGS. 7 to 9.

First, FIGS. 7 and 8 show the structure of a rewind operation button of a tape recorder, in which 21 is a first resin molded body, 2
2 is a first resin molded body 21 laminated on the upper surface of the first resin molded body 21.
This is a second resin molded body having a different color from the resin molded body 21 shown in FIG.

The first resin molded body 21 is provided with a recess 23 into which an operating member is press-fitted, and a protrusion 25 whose end surface becomes a rewind mode indicator mark 24 at the center of the upper surface thereof.
25 are provided. The end surfaces of the protrusions 25, 25 are formed to match the upper surface of the second resin molded body 22, and as shown in FIG. The end face of 25 is exposed as a rewind mode indicator mark 4. Furthermore, a protruding wall 26 is provided on the upper surface periphery of the first resin molded body 21.
are integrally formed, and a second resin molded body 22 is formed so as to be in close contact with this protruding wall 26. Note that the outer circumferential surface of the protruding wall 26 corresponds to the outer circumferential surface of the first resin molded body 21. The tip end portion of the protruding wall 26 appears as a lamination boundary line between the first and second resin molded bodies. Next, the production method of the operation button will be explained using FIG. 9. In FIG. 9, 27 is a first mold having a convex portion 28 for forming the operation member press-fitting recess 23; The first resin molded body 21 is formed between the second mold and the recessed portion for forming the outer surface of the first resin molded body 21 .

Here, a groove portion for forming the protruding wall 26 of the first resin molded body 21 is provided at the periphery of the bottom surface of the recessed portion of the second mold. Then, the first and second molds are joined together, and at this time, the space formed between the outer wall of the convex part 28 of the first mold 27 and the inner wall of the recessed part of the second mold When filled with resin, the first resin molded body 21 is formed. This first
After forming the resin molded body 21, as shown in FIG. The third mold 34 is joined to the first mold 27. The inner peripheral wall of the recess 33 of the third mold 34 has a tapered surface that widens toward the opening side of the recess 33 . When the third mold 34 is joined to the first mold 27 in this way, the outer peripheral edge of the protruding wall 26 of the first resin molded body 21 is connected to the third mold 27.
The protruding wall 26 is pressed toward the center of the first resin molded body 21 by engaging with a part of the inner circumferential wall of the recess 33 of the mold 34, and the elastic restoring force of the protruding wall 26 causes the protruding wall to 26 is pressed against the inner circumferential wall of the recess 33 of the third mold 34. Therefore, the space 38 created between the outer circumferential wall of the first resin molded body 21 and the inner circumferential wall of the recess 33 of the third mold 34 is sealed, and no resin flows into this space 38. It is possible to obtain a high-quality operation button with a clear boundary line between the first and second resin molded bodies and no burrs, scratches, etc. Effects of the Invention As explained above, according to the method for producing a laminated resin molded product of the present invention, when forming a second resin molded product after forming the first resin molded product, the first resin A protruding wall provided on the upper surface periphery of the first resin molded body is brought into contact with the inner circumferential wall of the recess of the third mold into which the molded body is inserted, and the dimensional difference between the outer shape and the first resin molded body is Even if this occurs, this dimensional difference is
Since the production method uses deformation of the protruding wall by the mold, burrs or scratches may occur at the boundary between the first resin molded body and the second resin molded body. This makes it possible to produce high-quality and uniform laminated resin molded bodies.

Moreover, the joint surface between the first resin molded body and the second resin molded body is widened by the outer surface of the protruding wall, and the second resin molded body is molded so as to bite into the inside of the protruded wall. The bonding strength between both resin molded bodies can be increased.

[Brief explanation of the drawing]

Fig. 1 is a top view showing a rewind operation button of a tape recorder which is an example of a conventional laminated resin molded product, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, Fig. Fig. 4 is a side sectional view of a mold for explaining the production method of the same operation button, Figs. 5 and 6 are side views showing examples of defective operation buttons obtained by the same production method, and Fig. 7 The figure is a top view showing a rewind operation button of a tape recorder which is an embodiment of the laminated resin molded product of the present invention.
FIG. 8 is a sectional view taken along the line C--C in FIG. 7 of the same operating button, and FIG. 9 is a side sectional view of a mold for explaining one embodiment of the method for producing the same operating button. 21...First resin molded body, 22...
Second resin molded body, 26...Protruding wall, 27...
....First mold, 29...Second mold, 3
3... Concavity, 34... Third mold.

Claims (1)

[Claims] 1. A second mold having a recess is joined to the first mold, and a space formed by the recess and the first mold is filled with resin to form a first resin molded body. Later, a third mold having a recess into which the first resin molded body is inserted is joined to the first mold, and the recess of the third mold and the upper surface of the first resin molded body are connected to each other. Fill the space formed by the resin with the second
In the method of forming a resin molded body and producing a laminated resin molded product, a groove is integrally provided on the bottom periphery of the recessed part of the second mold, and a protruding wall is provided on the top surface periphery of the first resin mold. After forming the first resin molded body,
The inner circumferential wall of the recess of the third mold into which the first resin molded body is inserted is formed into a tapered surface that widens toward the opening of the recess, and the third mold is joined to the first mold. At this time, the peripheral edge of the protruding wall of the first resin molded body comes into contact with a part of the inner circumferential wall of the recess of the third mold, and the protruding wall is pressed toward the center of the first resin molded body. A method for producing a laminated resin molded product, in which the protruding wall is pressed against the inner circumferential wall of the recess of the third mold by the elastic return force of the protruding wall.