JPS6244055A - Manufacture of rotor by 2-color molding - Google Patents

Abstract

PURPOSE:To simplify molding steps and a mold structure by sliding slide cores chamfered at the end to form a through hole in an amount smaller than the thickness of a rotor magnet in opposite direction to a disk to form a columnar portion. CONSTITUTION:Slide cores 36, 36 are held at the positions where are contacted with a mold plate 33 when molding a rotor magnet 10, and a projection 13 which is projected to the inside at the end of a through hole 12 is formed owing to the presences of chamfered portions 37, 37. After the magnet 10 is formed, a mold plate 38 having cavities corresponding to a tenon 21, a gear 23 and a disc 24 is docked with a mold plate 32, and the cores 36, 36 are moved down in the prescribed length. When a material for a rotor shaft 20 is injected to the plate 38, it is filled in the cavities, a shaft hole 11 and a cavity 35, thereby forming a 2-color rotor.

Description

[Detailed Description of the Invention] The present invention provides two rotors for use in small watch motors, etc.
The present invention relates to a manufacturing method for manufacturing by color molding.

The two-color molding technique itself is already well known and has been applied to the manufacture of various plastic parts.

Generally, when performing two-color molding, the two materials are often selected to weld together and easily join together, such as plastic materials of the same type with different colors.
Even in the case of different systems, materials that have similar melting temperatures (injection temperatures) and are easy to weld are selected. However, in the case of a rotor for a small motor, the characteristics must be given top priority.

That is, in the case of a rotor magnet, its magnetic properties are of paramount importance, and in the case of a rotor shaft (rotor pinion), low wear, low friction, smoothness of gear meshing, etc. are of paramount importance.

For this reason, when selecting suitable materials for the rotor magnet and rotor shaft, the weldability between the materials is extremely poor and they easily peel off, which is one of the obstacles to the practical application of two-color molded rotors. Ta.

Utility Model Publication No. 50-2528 for preventing such peeling.
A rotor according to publication No. 5 is known. In this rotor, a columnar part is formed by filling the through hole of the rotor magnet from a disc part on the rotor shaft side, and the tip of this columnar part has a partially enlarged diameter to prevent it from being pulled out. Met. However, this structure or method has the disadvantage that the molding process and mold structure for molding the rotor are complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a rotor by two-color molding, which can prevent separation of the rotor magnet from the rotor shaft without complicating the molding process and mold structure.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

The two-color molded rotor manufactured by the manufacturing method of the present invention is formed of a rotor magnet 10 and a rotor shaft 20,
The rotor magnet 10 is made of, for example, a mixed material of strontium ferrite and 6-nylon.
0 is made of polyacetal, for example. The rotor magnet 10 has a shaft hole 11 in its center, and a through hole 12 spaced apart from the shaft hole 11.

On the other hand, the rotor stem 20 protrudes through the shaft hole 11, has tenon parts 21 and 22 at both ends thereof, and further has a gear part 23.
and a disk portion 24 are integrally formed, and this disk portion 24 is joined to the upper end surface of the rotor magnet 10. Disc part 2
A columnar portion 25° 25 is formed to hang down from 4, and is fitted into the through hole 12. The columnar portion 25.25 has recesses 26, 26 at its base (near the joint surface), and the through hole 12.
An inwardly projecting protrusion 13.13 bites in at one end.

Next, a method for manufacturing a two-color molded rotor having the above structure will be explained.

First, in a first step, the rotor magnet 10 is formed using templates 31, 32, and 33 shown in the third figure. A pillar 34 for forming the shaft hole 11 is provided in a protruding manner on the template 33, and its tip end abuts against a cavity 35 for forming the tenon part 22 in the template 31. A slide core 36.degree. 36 is slidably fitted into the template 31, and the tip thereof is tapered with a chamfered portion 37.37 formed therein. This slide core 36.36 is held in a position where it comes into contact with the template 33 when forming the rotor magnet 10, and a protrusion 13 that protrudes inward at the end of the through hole 12 is formed due to the presence of the chamfered portion 37.37. be done.

After the rotor magnet 10 is formed, the template 33 is opened, and in the next stage, that is, the second step, the tenon part 21
．． A mold plate 38 having a cavity corresponding to the gear portion 23 and the disk portion 24 is docked on the mold plate 32, and the slide core 36, 36 is pulled down by a certain length (FIG. 4).

When the material for the rotor shaft 20 is injected into the template 38, the cavity, the shaft hole 11 and the cavity 35 are filled,
As a result, the two-color molded rotor shown in FIG. 1 is completed.

By forming the rotor magnet 10 and the rotor shaft 20 in this way, the most suitable material can be selected, and even if it is difficult to weld between the rotor magnet 10 and the rotor shaft 20, the relative Target rotation is prevented by the through hole 13 and the columnar part 26, and at the same time, the protrusion part 13 and the four parts 26 prevent the rotor magnet 10 from being pulled out in the axial direction of the rotor shaft 10.

As described above, according to the method for manufacturing a rotor by two-color molding according to the present invention, the slide core 35 with a chamfered tip for forming the through hole 12 is formed in the first step, and the thickness of the rotor magnet 10 is changed in the second step. By simply sliding the disc portion 24 in the opposite direction by an amount smaller than is simplified compared to the conventional method.

[Brief Description of the Drawings] Fig. 1 is a sectional view of a two-color molded rotor manufactured by the manufacturing method of the present invention, Fig. 2 is a plan view thereof, and Fig. 3 shows the first step of molding a rotor magnet. 4 is a sectional view showing a second step of joining and forming the rotor shaft to the rotor magnet. 10...Rotor magnet 11...Shaft hole 12...Through hole 20...Rotor shaft 23...Gear portion 24... ... Disc part 25 ... Column part 36 ... Slide core 37 ... Chamfered part and above Fig. 1 Fig. 2 Fig. 4

Claims (1)

[Claims] A first step of molding a rotor magnet having a shaft hole in the center and a through hole at a position spaced from the shaft hole from a plastic magnet material, and a rotor that passes through the shaft hole. A shaft, a disc part that joins to one end surface of the rotor magnet, a gear part located on the top of this disc part, and a columnar part that hangs down from the disc part and enters the through hole are made of plastic. a second step of integrally molding the slide cores with a beveled tip for forming the through holes in the first step; A method for manufacturing a rotor by two-color molding, characterized in that the columnar portion is formed by sliding in a direction opposite to the disk portion by an amount equal to the amount.