JPS5886849A - Manufacture of rotor for small-sized motor - Google Patents

Abstract

PURPOSE:To prevent the positional displacement of the center by injection- molding a supporter, which has a section covering an uneven section radially extending and a section burying an inner circumferential section and is made of resin, to a ring-shaped rotor magnet, to the surface thereof the uneven section is formed. CONSTITUTION:A member, the center thereof has a through hole 13 and to one main surface 14 and the other main surface 15 thereof a plurality of the convex sections 16 (or the concave sections) radially extending are each shaped, is used as the rotor magnet 11, the rotor magnet 11 is entered into a die for predetermined injection molding, and the supporter 12 made of synthetic resin is integrally formed to the rotor magnet 11. Here, the supporter 12 buries the inside of the through hole 13 of the rotor magnet 11, and is shaped by a section, the center thereof has a shaft inserting hole 17, and the section covering the convex section 16. Accordingly, displacement from the central position of the shaft inserting hole 17 can be reduced because the direction of shrinkage in case of the curing of resin is forcedly directed to the center.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a rotor for a pulse motor used in a timer, etc., or a small motor similar to the same. rotor).

An example of a rotor using conventional magnets will be explained with reference to FIGS. 1 and 2. A ring-shaped magnet (1) shown in FIG. 2 and a rotor magnet made of synthetic resin as shown in FIG. It has a structure in which a support body (2) is provided.

In order to reduce the weight of the rotor and the moment of inertia, the diameter of the through hole (3) of the magnet (1) should be made as large as possible, and the shaft of the magnet (II) should be made as large as possible. It has a structure in which the number of parts of the rotor magnet support (2) made of synthetic resin having an insertion hole 141 is increased.By the way, the support made of synthetic IrIR resin +2
1 is generally made by injection molding, so resin shrinkage becomes a problem.

If the injection pressure is increased, the density will increase and the center of the shaft insertion hole (41) will be less likely to shift due to shrinkage.

Due to the excessive force applied to the rotor magnet ILK, cracks were generated in the a-ta magnet (1), and the rotor magnet (1) was cracked.
1) f) *''' Defects occur due to scratches. Therefore,
Support (2) with low injection pressure that does not cause cracks
I have to set up a gate. Therefore, the density of the molten resin becomes smaller, and the density near the sprue becomes smaller than that of the gate.
There was a drawback that the shrinkage of the resin was not uniform and the center of the shaft insertion hole +41 did not coincide with the center of the rotor, resulting in irregular rotation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a rotor that can prevent the center from shifting due to shrinkage of the resin.

To achieve the above object, the present invention includes a step of preparing a ring-shaped α-ta magnet having a plurality of radially extending convex portions or concave portions on at least one main surface, and By injecting a synthetic resin into a mold marked IIJ, a synthetic resin is formed, which has a shaft insertion hole in the center and has a part that fits into the inner part of the rotor magnet, and a part that is behind the convex part or concave part. a step of integrally forming a resin rotor magnet support Y on the rotor magnet;

The present invention relates to a method of manufacturing a rotor for a small motor consisting of:

According to the present invention, since the rotor magnet is provided with radial convex portions or concave portions, injection molding is also possible.

Shrinkage of synthetic 41g fat toward low density areas such as sprues is limited. First, the radial convex portions or concave portions act to direct the shrinkage direction of the resin toward the center, thereby reducing the shrinkage toward the sprue. Therefore, it becomes possible to easily form a rotor with less eccentricity and misalignment of the shaft insertion hole.

The present invention will be described in detail below with reference to FIG.

The rotor of the pulse motor according to the second embodiment of the present invention uses a ferrite ring-shaped rotor magnet aυ shown in FIGS. 3 and 4. As shown in the figure, a synthetic resin rotor magnet support (1
21χ is one thing.

The ring-shaped rotor magnet 1υ is not only provided with a through hole a1 for integrally connecting it to a support made of synthetic resin, but also has six holes on one main surface 11Q4) and the other main surface a3. Convex portions αQ are provided radially.

The diameter of this rotor magnet aυ is 15 mm, and the thickness is 3
mm, the diameter of one through hole is 8 mm, the height of the convex part Q61 is 0-5 mm, and the width of the convex part (161) is 1 mm. '
When installing AIT, insert a magnet AUW into the mold.

Injection mold. This results in Figure 5 and #! As shown in Figure 6, a synthetic resin support α2 is integrated with the magnet AV.
A ground rotor central portion is formed. In addition, the support 0 on the resin surface consists of a part that fills 11ll of the through holes of the rotor magnet (Qll), and a part that stores the convex part 10.

There is a shaft insertion hole Qn in the center of the synthetic resin support σ.
It is impossible to arrange the injection molding sprue in the center because it is necessary to provide a Therefore, the sprue is located off-center. If a synthetic resin is heated and melted in a cylinder and then injected into the mold from a nozzle using a plunger or screw, the resin is injected into the mold (trade name: Shellacon).
The resin spreads throughout the space inside the mold. However, it is inevitable that the resin density near the sprue will be small. In the conventional case, the convex portion αQ as related to the present invention is not provided.

It is not possible to ignore the contraction of the resin in the area where the resin density is low, and #! ] Shaft insertion hole (4) in the figure
The deviation from the center of the rotor at the position was large.

On the other hand, if the protrusions a1'' are provided radially toward the center as in the present invention, and the oil is allowed to flow therein, the direction of contraction of the resin when the molten resin hardens is forced. Since the amount of contraction toward the center and toward the sprue where the density is smaller is ignored compared to the amount of contraction toward the center, the amount of contraction toward the center is dominant. ) from the center position will be reduced.

#! Figure 7 shows the measured eccentricity of the completed rotor. The curve (1) drawn based on the ○ mark shows the result of the real IItlA example, and the curve #(b) drawn based on the X mark shows the conventional result. Both show the distribution of the number of 350 samples with respect to the value of 7. Normally, if it is 0.07 mm or less, it is considered to be a good product! Since the rotor is usable, the rotor made according to the present invention is of good quality. In contrast, nearly half of conventional rotors are defective, so it is necessary to check the finished product.

As is clear from the above, if the convex portions are provided in a radial manner based on the present invention, the contraction toward the center will be greater than the contraction toward the portions where the resin density is low.

Eccentricity of the shaft insertion hole αη does not occur, and the deviation per rotation is reduced.

FIG. 8 and FIG. 9 show an embodiment of JI2 of the present invention. In this example, one and the other main surfaces of the magnet (ill) are flat surfaces, and the convex portions are flat.
The synthetic resin components aayxe are arranged radially, and the synthetic resin component aayxe is disposed as shown by the chain line in FIG. Even if I'm busy.

#! ] It is possible to obtain the same effects as in the embodiment.

Figure 10 and Figure 10 are #! of the present invention. Example 3 is shown below. In this IM example, concave portions 1211 are provided radially on one and the other main surfaces Q41Q51 of the magnet αυ, and the synthetic resin component az is applied to rg! When the resin is removed, the recess Qυ forces the resin collection #i toward the center. Even if you configure it like this #
! ] It is possible to obtain the same effects as in the embodiment.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can be further modified. For example, it may be provided only on one main surface of the convex portion ue or the rotating portion Qυ of the magnet αD. Even in this case, the number of 7s is reduced compared to the conventional case.

[Brief explanation of drawings]

#! Figure 1 is a sectional view showing a conventional rotor of a pulse motor.
Figure 2 is a plan view of the rotor magnet in Figure 1, WIa
The figure is a plan view of a rotor magnet of a pulse motor according to an embodiment of the wJl of the present invention, Figure 4 is a sectional view taken along the line PI-4 in Figure 3, and Figure 5 is an integrated structure of the magnet in Figure 3 with iIR resin. Top view of the rotor, #! Figure 6 shows ■-W* in Figure 5.
The cross-sectional view, Figure 7 is a graph showing the measurement results of runout accuracy, and Figure 8 is #! A plan view of the rotor magnet according to Example 2, FIG. 9 is W, a sectional view of ff-1[]1i in FIG.
FIG. 0 is a top view of a rotor magnet according to a third embodiment of the present invention, and FIG. In the symbols used in the drawings, Qll is the magnet, (121 is the synthetic resin support, σ4 is the through hole, α41 (lω is the main surface, ue is the convex part, and αη is the shaft insertion hole. Agent Nori Takano, Figure 1 Figure 2 Il, J Figure 8- ■1 Figure 10 II"1 X[" Figure 9'11 Figure 11

Claims (1)

[Claims] (1) A step of preparing a ring-shaped rotor magnet having a plurality of radially extending convex portions or concave portions on at least one main surface. By injecting the synthetic resin into the mold from the sprue of the injection molding mold, a shaft insertion hole Y is formed in the center, and a portion filled with the inner hook Y of the rotor magnet and the convex or concave portion Y are formed. and a step of integrally forming a rotor magnet support made of synthetic resin with the rotor magnet. A method of manufacturing a rotor for a small motor consisting of: