JPH0372450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a plastic injection molded product such as an actuator that is molded integrally with a bearing or the like using a resin.

(Prior Art) Actuators have been known that have a main body portion molded from resin and a bearing that has one end buried in the main body portion and the other end protrudes. To mold such an actuator, the hollow bearing 4 is inserted into the recess 5 of the lower mold 2 having the guide 8 as shown in FIG. While fixing the bearing 4 in between, resin is injected into the cavity 3 for forming the main body part.
In this case, in order to prevent resin from entering between the upper and lower end surfaces of the bearing 4 and the upper and lower molds,
The overall length of the bearing 4 is made to match the distance between the upper wall surface 7 of the upper die 1 and the bottom surface 9 of the recess 5.

(Problems to be Solved by the Invention) However, the actuator as described above has a drawback that if the dimensions of the bearing 4 become even slightly longer, the bearing 4 will buckle and deform when the mold is clamped.

(Means for Solving the Problems) In order to solve these problems, the present invention is a bearing in which the tip of the part of the bearing that is buried in the resin is formed into a thin shape and the overall length is made longer. It is.

(Function) Since the bearing is made longer like this, the gap is closed and the resin does not get into the gap. Also, since only the tip of the bearing is shortened when the mold is clamped, buckling as described above can be prevented.

(Example) FIG. 1 shows an example of the present invention. In the figure, parts similar to those in FIG. 2 are given the same reference numerals and their explanations are omitted, but the parts that differ from those in FIG. In addition, the overall length L of the bearing 4 is made longer than the distance between the top wall surface 7 and the bottom surface 9, as shown by the dotted line. When the mold is clamped in this way, the upper end 11 of the bearing is compressed by the upper mold 1 and deformed within the elastic limit, and due to the spring force, the lower end surface is brought into close contact with the upper mold and the lower mold, respectively, to prevent resin from entering. prevent. Note that the outer diameter of the bearing 4 is made approximately equal to the inner diameter of the recess 5, as in the conventional case, to prevent resin from entering the gap 6. In this way, the bearing does not undergo buckling deformation during mold clamping.

Although the tip of the bearing is made thin by providing the groove 10 as described above, the present invention is not limited to this, and the tip may be made thin by sharpening the tip.

(Effects) As described above, according to the present invention, buckling of the bearing can be prevented in an actuator in which the bearing is integrally molded into the main body made of resin.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is a sectional view showing a conventional example. 1... Upper die, 2... Lower die, 4... Bearing.

Claims (1)

[Claims] 1. First and second injection molding molds forming a cavity for injection molding the main body, a recess provided on the first inner surface of both molds forming the cavity, and an outer periphery near the tip. a rod-shaped body, the tip of which is provided with a thin-walled portion that rotates at least once; Insert the part not including the tip thin part into the recess, and
and clamping a second mold to form the cavity, deforming the thin end portion to fix the rod-shaped body between the first and second inner surfaces, and injecting resin into the cavity. Characteristic plastic injection molding method.