JPH065976B2 - Method and apparatus for manufacturing radially anisotropic resin magnet rotor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method and an apparatus for manufacturing a radial anisotropic resin magnet rotor, and more particularly to a stepping motor or the like which has low inertia and excellent left-right balance of torque. The present invention relates to a method and an apparatus for manufacturing a resin magnet rotor useful for the above.

"Prior Art""Problems to be Solved by the Invention" Conventionally, for example, two types of rotors for permanent magnet type stepping motors are known. One is simply replacing the sintered ring magnet with a resin magnet, and the shaft and the ring-shaped resin magnet are connected and fixed by a member such as aluminum, SUS, or Shin-Chiyu, and the other one is the ring-shaped magnet and the shaft. When,
A connecting portion for connecting the two is integrally formed, and the connecting portion is connected to either end of the inside of the ring-shaped magnet. However, in the former case, the left-right balance of the torque for a stepping motor is good, and there is no bias in the magnetic characteristics, but the inertia is not much different from that of the sintered magnet, and the manufacturing process is also It is complicated.
On the other hand, in the latter case, the inertia is reduced, but the magnetic characteristics are left / right unbalanced, and as a result, the torque is left / right unbalanced.

Therefore, the present inventors have developed a radial anisotropic resin magnet rotor as shown in FIGS. 1 (A) and (B), and filed a utility model registration application. That is, the rotor is composed of a ring-shaped resin magnet (1), a shaft (3), and a connecting portion (2) for connecting the two, and the connecting portion is the center of the inner peripheral surface of the magnet (1). Consisting of a structure connected to.

However, when the rotor having such a structure is formed by using a mold as shown in FIG. 2 or 3, an imbalance occurs in the magnetic characteristics of the ring-shaped magnet on the left and right of the connecting portion. That is, in FIG. 2, the magnetic component in the resin magnet composition pressed into the ring-shaped magnet portion cavity (7a) of the cavity (7) is oriented by the generated radial magnetic field, and the connection portion cavity (7b) is oriented. On the right side of the ring-shaped magnet portion cavity (7a), the radial magnetic field acting on the ring-shaped magnet portion cavity (7a) becomes weaker than that on the left side because the connection portion cavity (7b) considerably obstructs the inflow of magnetic flux.

On the other hand, also in FIG. 3, as in the case of FIG. 2, an imbalance occurs in the radial magnetic field.

Thus, in both cases of FIG. 2 and FIG. 3, it is unavoidable that the magnetic characteristics become non-uniform on the left and right of the connecting portion of the ring-shaped magnet.

“Means for Solving Problems” As a result of earnest research in view of such actual circumstances, the present inventors have found that the above problems can be solved all at once by adopting a method of supplying magnetic flux from both sides of the cavity. The present invention has been completed under the heading.

That is, the first aspect of the present invention is to integrally mold a rotor including a radially anisotropic ring-shaped resin magnet, a shaft, and a connecting portion that connects the magnet and the shaft with each other. The magnetic field generating mechanism is disposed substantially at the center in the longitudinal direction, the magnetic field generating mechanism is a repulsive different type, and the magnetic flux is preferentially supplied from the side surfaces of the facing magnetic poles to orient the magnetic field. A second method of the present invention relates to a method of manufacturing a radial anisotropic resin magnet rotor having good symmetry, in which cylindrical ferromagnetic inner poles (5) and (that form one end of the yokes (9) and (9 ′), respectively. 5 '), a connecting portion cavity (7b) defined by the facing surface, and a ring-shaped magnet portion cavity (7b) defined by the facing surface of the inner poles (5) (5') and the outer pole (6). 7a), and the cavity (7b) is approximately the center of the cavity (7a). A cavity (7) arranged in a portion, and the cavity (7b) extends from a substantially central portion thereof to the inner pole (5).
A shaft accommodating portion (8) extending to (5 ') is provided, and coils (4) (4) (4) (4) are provided between the return yokes (10) (10') and the yokes (9) (9 ') connected to the return yokes. ′) Is provided, and the coil has a magnetic circuit configured so that the inner poles (5) and (5 ′) have the same magnetic polarity by passing currents in opposite directions, and further, the inner pole (5 ′) is a cavity. The ejector pin (15) provided with the runner (13) and the sprue (12) for communicating the nozzle (11) with the nozzle (11) is operated by the ejector rod (14) to the cavity (7a).
And a manufacturing device for a radial anisotropic resin magnet rotor, which is characterized in that it is disposed so as to face each other.

The present invention will be described with reference to the drawings showing the embodiments. In FIG. 4, the confronting surface of the cylindrical ferromagnetic inner poles (5) (5 ') forming one end of each of the yokes (9) (9') is shown. The cavity (7b) comprises a connecting portion cavity (7b) and a ring-shaped magnet portion cavity (7a) formed by the facing surfaces of the inner poles (5) (5 ') and the outer pole (6). ) Is formed at a substantially central portion of the cavity (7a), and the connecting portion cavity (7b) formed by the facing surfaces of the inner poles (5) and (5 ') has the cavity (7). A shaft accommodating portion (8) extending from the center to the inner poles (5) and (5 ') is provided. Inner pole (5)
(5 ') are connected to the yokes (9) and (9'),
A coil (4) is provided around the yokes (9) (9 ').
(4 ') is provided. The outer pole (6) is connected to the return yokes (10) (10 '). The cavity (7) communicates with the nozzle (11) via the runner (13) and the sprue (12). The diagonal line is made of a ferromagnetic material, and the stippled area is made of a non-magnetic material.

The method of manufacturing the rotor of the present invention will be described with reference to FIG. 4. The resin magnet composition press-fitted from the nozzle (11) passes through the sprue (12) and the runner (13) and is heated and melted in the cavity ( 7) filled inside. Then, the magnetic component of the resin magnet composition is oriented by the radial magnetic field generated in advance. After the mold is opened, the ejecting rod (14) is moved forward, and the ejecting pin (15) releases the molded product to take it out.

"Examples" Hereinafter, the present invention will be described based on Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1, Comparative Examples 1 and 2 The product dimensions are an outer diameter of 40 mm, an inner diameter of 34 mm, and a height of 17 m.
m, the thickness of the connecting portion was 1 mm, the resin magnet composition shown in Table 1 was kneaded twice at 230 ° C. with a 32 mm full flight kneader and then cooled, and then crushed and pelletized. Using the pellet, molding was performed using the mold shown in FIG. 4 under the magnetic field orientation conditions shown in Table 2.

On the other hand, for comparison, molding was performed in the same manner except that the molds shown in FIGS. 2 and 3 were used, and Comparative Examples 1 and 2 were obtained.

Table 3 shows the results of measuring the left and right magnetic properties of the obtained rotor, which are at the boundary with the connection portion.

Table 1 Strontium ferrite powder (average particle size 1.1 μm) 90 wt% Polyamide 12 10 KBM603 (manufactured by Shin-Etsu Chemical) 0.5 Irganox 1098 (manufactured by Ciba Geigy) 0.5 Table 2 Mold temperature 80 ° C. injection 〃 300 ° C. injection Pressure 1.5t / cm ² Cooling time 20 seconds Magnetic field application time 10 seconds Magnetic field in the cavity 6000 Oe (left and right) When the rotor obtained in Example 1 was incorporated into a stepping motor and a drive test was performed, the left and right torque balance was good. On the other hand, the rotors of Comparative Examples 1 and 2 were unbalanced in the left and right and could not be put to practical use.

[Operation] [Effect of Invention] As described above, according to the present invention, by applying repulsive magnetic fields from both sides of the cavity, it is possible to satisfactorily solve the problem of left-right unbalance of torque due to magnetic field interruption by the connecting portion. It is possible to provide a rotor having good magnetic characteristics.

[Brief description of drawings]

1 (A) and (B) show an example of a rotor which is the object of the present invention, (A) is a perspective view, (B) is a sectional view taken along line XX,
2 and 3 are cross-sectional views showing a main part of a conventional mold, and FIG. 4 is a cross-sectional view showing an embodiment of the mold of the present invention. 1 ... Ring-shaped resin magnet, 2 ... Connection part 3 ... Shaft, 4, 4 '... Coil 5, 5' ... Inner pole, 6 ... Outer pole 7 ... Cavity, 7a ... Ring magnet Portion 7b ··· Connection portability · 8 · · Shaft housing 9,9 '· · Yoke 10, 10' · Return yoke 11 · · Nozzle, 12 · · Sprue 13 · · Runner, 14 · · Overhang Stick 15 ... Protruding pin

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Takeshi Sakauchi, 2-1-1 Hiei Tsuji, Otsu City, Shiga Prefecture, Kanagawa Fuchi Chemical Industry Co., Ltd., Sakamoto Plant (56) Reference JP-A-57-187914 (JP, A)

Claims (2)

[Claims] 1. When integrally molding a rotor composed of a radial anisotropic ring-shaped resin magnet, a shaft, and a connecting portion connecting the magnet and the shaft, the connecting portion is formed in the longitudinal direction of the magnet. Good magnetic symmetry, characterized in that the magnetic field generation mechanism is a repulsive magnetic field system and the magnetic field is preferentially supplied from the side surface of the facing magnetic pole to orient the magnetic field. Of manufacturing a new radial anisotropic resin magnet rotor. 2. A connecting portion cavity (7b) defined by the confronting surfaces of the cylindrical ferromagnetic inner poles (5) and (5 ') forming one ends of the yokes (9) and (9'), respectively. The inner poles (5) (5 ') and the outer pole (6) are formed by a ring-shaped magnet portion cavity (7a) defined by facing surfaces, and the cavity (7b) is an abbreviation of the cavity (7a). A cavity (7) arranged in the center is provided, and the connection part cavity (7b) is provided with an inner pole (5) from substantially the center thereof.
A shaft accommodating portion (8) extending to (5 ') is provided, and coils (4) (4) (4) (4) (4) are provided between the return yokes (10) (10') and the yokes (9) (9 ') connected to the return yokes. ′) Is provided, and the coil has a magnetic circuit configured such that the inner poles (5) and (5 ′) have the same magnetic polarity by passing currents in opposite directions, and the inner pole (5 ′) is a cavity. The ejector pin (15) provided with the runner (13) and the sprue (12) for communicating the nozzle (11) with the nozzle (11) and operated by the ejector rod (14) is attached to the ring-shaped magnet portion cavity (7a). An apparatus for manufacturing a radially anisotropic resin magnet rotor, which is arranged so as to face each other.