JPS63141712A - Injection molding process of plastics - Google Patents

Abstract

PURPOSE:To prevent the buckling-deformation of a bearing by a method in which while preliminarily forming the tip of the part of a bearing buried in resin into thin wall, the total length thereof is caused to be a little longer at the injection molding by the actuator, etc. with a bearing in a main body. CONSTITUTION:A groove 10 is provided at the periphery adjacent to the tip of a bearing 4, and the total length L of the bearing 4 is caused to be longer than the distance between the surface 7 of upper wall and the surface 9 of bottom as shown by a dotted line, while causing the upper end 11 to be like spring. When the mold is clamped, the upper-end 11 of the bearing is compressed by a top force 1, and is deformed in its elastic limit. By said spring force, the upper and lower ends of the bearing are caused to be closely in contact with the top force and the bottom force, thereby preventing the intrusion of resin. The outer diameter of the bearing 4 is almost equal to the inner diameter of a recessed portion 5 similarly to a former device, whereby the intrusion of the resin into the clearance is prevented, and the bearing does not suffer buckling deformation at mold clamping.

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 integrally molded with a bearing or the like using a resin.

(Prior Art) Actuators are known that have a main body portion molded from resin and a bearing that has one end buried in the main body portion and a bearing that protrudes from the other end. To mold such an actuator, a hollow bearing 4 is inserted into the recess 5 of the lower mold 2 having a guide 8 as shown in FIG. While fixing the bearing 4 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 total length of the bearing 4 is the same as the upper wall surface 7 of the upper mold 1 and the bottom of the recess 5. 9
Match the spacing between.

(Problems to be Solved by the Invention) However, the actuator as described above has a drawback that if the dimensions of the bearing 40 become even slightly longer, the bearing 4 will buckle and deform when the mold is clamped.

(Means for Solving the Problems) The present invention is intended to solve these problems.

(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 +3 direct demand portion 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, the same parts as in Fig. 2 are given the same reference numerals and their explanations are omitted, but the parts that differ from Fig. 2 are that a groove 10 is provided on the outer periphery near the tip of the bearing 4, and the upper end point is provided. . When the mold is clamped in this way, the upper end 11 of the base T-socket 7 is compressed by the upper mold 1 and deformed within the elastic limit, and due to the spring force, the upper and lower end surfaces are brought into close contact with the upper mold and the lower side, respectively. Prevents resin from entering. Note that the outer diameter of the bearing 4 is made approximately equal to the white ball of the recess 5 to prevent resin from entering the gap 6, as in the conventional case. In this way, the bearing does not undergo buckling deformation during mold clamping.

In addition, although the tip of the bearing is made circular by providing the groove 10 as described above, the tip is not limited to this and may be made into a sharp shape by making the tip pointed.

(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 the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 (d) is a sectional view showing a conventional example.

Claims (1)

[Scope of Claims] First and second injection molding molds forming cavities for injection molding the main body, recesses provided on first inner surfaces of the molds forming the cavities, and tips. a rod-shaped body, the rod-shaped body having a thin wall portion at the tip portion that rotates at least once around the outer periphery of the hollow portion, and having an overall length longer than the distance between the bottom surface of the recessed portion and the second inner surface of the void space facing the bottom surface; and inserting a portion of the rod-like body that does not include the thin end portion into the recess, and clamping the first and second molds to form the cavity and deforming the thin end portion. A method for injection molding plastics, comprising fixing the rod-shaped body between first and second inner surfaces and injecting resin into the cavity.