JPH0159897B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention is directed to molding a synthetic resin molded product, such as a horn pad, which is assembled to a boss plate of an automobile steering wheel, in which a protruding part with an undercut part is formed on the surface. Regarding injection molds.

(Prior art) Conventionally, for example, with synthetic resin horn pads,
As shown in FIG. 4, a protruding part 10a is formed on the back surface, and includes a space part 10c and an undercut part 10b, which can be attached to a boss plate. When molding such a molded product 10, a slide core, or An injection mold using an inclined extrusion core was used.

However, the strength of slide cores, inclined extrusion cores, etc. must be larger than a predetermined size, and if a slide core with sufficient strength is used, the protrusion
When molding a molded product 10 in which a flange portion 10d is formed on the side of the protruding portion 10a near a, it becomes impossible to secure enough movement space for the slide core, etc., and the shape of the molded product 10 must be changed. , or the molded product protrusion 10a when releasing the mold after molding.
The solution was to forcefully remove the mold from the mold.

For example, in the injection mold 1 shown in FIGS. 9a to 9c, 2 is a fixed mold, 3 is a movable mold, and 4 is a movable mold 3.
5 is an extrusion pin, 6 is an extrusion core, 7 is a slide core, 8 is a spring that pulls back the extrusion core 6, 9 is a molded product space 10
This is a core pin fixed to the movable mold 3 for molding c. When the mold is opened, as shown in FIG.
Then, as shown in FIG. 9c, after the slide pin 7 stops moving at its flange 7a, the push-out pin 5 is pushed out further to push up the inclined extrusion core 4, and the molded product protrusion 10a is pushed up. Extruded core 6
I had to force myself to remove it.

However, if the molded product protrusion 10a is forcibly removed in this manner, there is a risk that the undercut portion 10b may be scraped off or the protrusion 10a itself may be deformed and tilted.

(Object of the Invention) The present invention provides a method for molding a synthetic resin molded product in which a protruding portion including an undercut portion protrudes from the surface and the space around the protruding portion is narrow.
It is an object of the present invention to provide an injection molding die which can be molded without changing the shape of the molded product and which can be released from the mold without damaging or deforming the protrusion after molding.

(Structure of the Invention) The gist of the present invention is an injection mold for molding a synthetic resin molded product in which a protruding portion having an undercut portion is formed on the surface, the movable mold having a movable mold for releasing the molded product. An extrusion pin, a plurality of extrusion cores that are fitted into a movable mold during molding to form a recess for molding a protrusion, and connected to a core extrusion pin that supports each extrusion core and extrudes the extrusion core from the movable mold. An injection mold is characterized in that it comprises a support member having elasticity.

(Example) Figures 1 to 3 show an injection mold according to an embodiment of the present invention, and are sectional views sequentially showing the opened state, Figure 5 is a sectional view taken along line V-V in Figure 1, and Figure 6 is - in Figure 1
The sectional view, FIG. 7, is a - sectional view of FIG. 1.

The injection molding die 11 of the embodiment includes a fixed die 12 and a movable die 13, and the fixed die 12 is formed with a gate, a runner, a sprue, etc. (not shown).

The movable mold 13 is equipped with an extrusion pin 15 for releasing the molded product 10, and also has two approximately semi-cylindrical extrusion pins arranged to surround the protrusion 10a so as to mold the molded product protrusion 10a. The extrusion cores 16, 16 are fitted into the recess 13a of the movable mold 13 (see FIG. 5).

The extruded cores 16, 16 are supported by countersunk screws at the tips of support members 18, 18 made of leaf springs, respectively, and the rear ends of the support members 18, 18 are supported by core pins that form a space 10c in the protrusion of the molded product. 1
9 and the pin 14 to the core extrusion pin 17 which can be extruded simultaneously with the extrusion pin 15 for a predetermined distance (until the extrusion core 16 separates from the movable recess 13a).
14 (see Figures 6 and 7).
Note that the support members 18, 18 are disposed so as to urge the extrusion cores 16, 16 to close each other.

Next, the operating mode of this mold 11 will be explained.

First, fixed mold 12, movable mold 13, extrusion core 1
6. A synthetic resin material is injected into the cavity 11a formed by the core pin 19 and the like to form the molded product 10 (FIG. 1).

Thereafter, the mold is opened, the extrusion pin 15 and the core extrusion pin 17 are extruded by communicating with the movable mold 13, and the molded product 10 is released from the movable mold 13 (FIG. 2).
In addition, at this time, the extrusion cores 16, 16 are connected to the movable mold 13.
The core extrusion pin 17 is then separated from the recess 13a, and the extrusion distance is regulated and the core extrusion pin 17 is stopped.

After that, push out the push-out pin 15 further (third
figure). Then, the molded product protrusion 10a is attached to the extrusion core 1.
6, 16, but the extrusion core 16,
16 are support members 18, each made of a leaf spring;
18, and when the molded product undercut portion 10b exits from the extrusion cores 16, 16,
The supporting members 18, 18 are easily elastically deformed so as to open their legs, and the molded product protrusion 10 is released from the extrusion cores 16, 16.
The molded product 10 is released from the mold without being damaged or deformed, and the molded product 10 can be taken out using a separate removal device or the like to obtain a product.

Therefore, in the injection mold 11 of the embodiment, as long as there is enough space for the extrusion cores 16, 16 to open by the amount of the protrusion of the molded product undercut portion 10b after the extrusion cores 16 move in the mold opening direction, the protrusion portion 10a may be damaged or deformed. The molded product 10 can be released from the mold without changing the shape of the molded product 10 even if the area around the protrusion 10a is narrow, which could not be molded using a conventional slide core or the like.

In addition, in conventional molds that use slide cores, etc., it was necessary to form highly precise dovetail grooves for moving the slide cores, etc., but if the structure is configured as in the example, dovetail grooves are not necessary. As a result, it does not take much time to process the mold.

In the embodiment, the molded product protrusion 10a is molded using two extrusion cores and a core pin 19, each supported by a support member 18. Molding may be performed using a plurality of extrusion cores, such as three or four, as long as they are each supported by a member.
6 to close, the extrusion core 16 can be detached from the movable mold 13 by extrusion of the core extrusion pin 17, and the extrusion core 1 can be detached from the movable mold 13 after detachment.
6 may be an elastic member that can be opened to separate the extruded cores 16 from each other due to their own weight or the like.

Furthermore, if the support member 18 is a leaf spring that urges the extrusion core 16 to open, the legs can be opened automatically when the mold is opened.

Furthermore, in the embodiment, the molded product protrusion 10a
Although a space portion 10c is shown in FIG. 8, it is of course possible to form a protruding portion 20b of a molded product 20 as shown in FIG. 8 without using the core pin 19. Note that in such a case, the protruding angle of the undercut portion 20b in the protruding portion 20a is preferably an obtuse angle, but after the extrusion core 16 is separated from the movable mold 13,
It may be at a slightly acute angle as long as it can be opened under its own weight.

(Effects of the Invention) In the injection mold according to the present invention, a plurality of extrusion cores forming the protrusion of the molded product are fitted into a movable mold during molding, and further connected to a support member having elasticity that allows the legs to be opened. Once the extrusion core is separated from the movable mold, the legs can be opened, allowing the molded product to be released without damaging or deforming the protrusion of the molded product, and creating a space around the protrusion of the molded product where the extrusion core opens. The molded product can be molded as long as the material is available, and molded products that could not be molded using conventional slide cores can be molded without changing the shape.

In addition, conventional molds using slide cores require dovetail grooves, which takes time and effort to process, but the mold of this invention eliminates the need for dovetail grooves, making mold processing time-consuming. This has the effect of not causing any damage.

[Brief explanation of drawings]

1 to 3 show an injection molding mold according to an embodiment of the present invention, and sequentially show a cross-sectional view showing the mold open state, and a fourth
The figure is a partial perspective view showing the molded product, FIG. 5 is a cross-sectional view of FIG. 1, FIG. 6 is a cross-sectional view of FIG. 1,
FIG. 7 is a sectional view taken from FIG. 1, FIG. 8 is a partial front view showing another molded product, and FIGS. 9a to 9c are sectional views showing a conventional mold and sequentially showing the mold opening state. DESCRIPTION OF SYMBOLS 1, 11... Injection mold, 2, 12... Fixed mold, 3, 13... Movable mold, 10, 20... Molded product, 10a, 20a... Projection part, 10b, 20b
...Undercut part, 15...Extrusion pin, 16...
... extrusion core, 17 ... core extrusion pin, 18 ... support member.

Claims (1)

[Claims] 1 An injection mold for molding a synthetic resin molded product having a protruding part with an undercut portion formed on the surface, the movable mold includes an extrusion pin for releasing the molded product, and a movable mold that is fitted into the movable mold during molding. A plurality of extrusion cores that are brought together to form a recess for forming the protrusion, and an elastic member that supports each extrusion core and is connected to a core extrusion pin that extrudes the extrusion core from the movable mold. An injection mold, characterized in that it comprises a supporting member.