JPH02111253A - Manufacture of stator for stepping motor - Google Patents

Abstract

PURPOSE:To form the shapes of pole teeth not magnetically saturated freely, and to obtain a stator for a stepping motor having high machine accuracy and excellent productivity by molding the stator for the PM type stepping motor with a plurality of the pole teeth arranged in the circumferential direction through press forging. CONSTITUTION:A die 101 is formed to a shape that the form of an outer yoke is transferred, and die pole teeth 104 are arranged in the circumferential direction. A manufacturing process in the figure shows sealed type forging, and displays the state of the setting of a raw material. The raw material takes the external shape of the outer yoke and a ring shape in approximately the same size as the inside diameters of the pole teeth. The raw material 103 is pushed by a punch 102 and flows along the form of the die, and is formed to the shape of the outer yoke. An inner yoke is also manufactured through the same method as the outer yoke.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a stator for a stepping motor.

[Background Art] Stepping motors are widely used in the world, including for controlling information devices. Among these, there is a stator with a plurality of pole teeth arranged in the circumferential direction, a coil wound around each pole tooth to generate magnetic flux, and a plurality of magnetized magnets on the outer peripheral surface facing the stator pole teeth. PM type stepping motors, which are composed of a rotor having permanent magnets, are widely used in magnetic recording devices such as FDDs and HDDs, printers, etc. because of their low cost.

The method for manufacturing the stator of a PM stepping motor is to first punch out a sheet material with expanded pole teeth, and then bend the pole teeth so that they are arranged in a cylindrical shape. The thickness of the stator and pole teeth is determined by the thickness of the raw material, and cannot be processed into different thicknesses.

[Problems to be Solved by the Invention] However, in the conventional technology as described above, in response to the demands for high resolution and high speed accompanying the high performance of equipment, it is difficult to increase the number of pole teeth, improve machining accuracy, and reduce the number of pole teeth. Although it is necessary to increase the effective magnetic flux that acts between the magnetic flux and the permanent magnet without causing magnetic saturation, it has the following problems.

1. When increasing the number of pole teeth for higher resolution, the pole tooth width becomes narrower, which reduces the mechanical strength of the pole tooth root, making it easier for teeth to curve, resulting in decreased motor performance and yield. The cost will increase due to the decrease in

2. When the pole tooth width becomes thinner and becomes about the same as the plate thickness, punching becomes very difficult. Furthermore, since the number of pole teeth is limited, it is difficult to achieve high resolution.

3. When bending the pole teeth, dimensional accuracy may be lost due to springback, and the stator may be distorted due to stress associated with bending.

4. Since the thickness of the pole teeth is determined by the thickness of the raw material, the roots of the pole teeth are likely to be magnetically saturated.

5. Since the bent portion is thinner than other portions, magnetic saturation is more likely to occur, reducing motor performance.

Therefore, the present invention is intended to solve the above-mentioned drawbacks.The purpose of the present invention is to achieve high mechanical precision by allowing the shape of the pole teeth to be freely shaped without magnetic saturation in order to cope with high division and high speed. An object of the present invention is to provide a method for manufacturing a stator for a stepping motor with excellent productivity.

[Means for Solving the Problems] The method for manufacturing a stator for a stepping motor of the present invention includes:
A stator of a PM type stepping motor having a plurality of pole teeth arranged in the circumferential direction is formed by press forging.

[Example] The present invention will be explained in detail below using examples.

FIG. 6 is a cross-sectional perspective view of a PM type stepping motor suitable for applying the present invention, in which 1 is a stator;
Typically, a PM type stepping motor is composed of two stators. 2 is a rotor consisting of a multipolar magnetized permanent magnet, 3 is a motor shaft, 4 is a coil that excites the stator, 5 is a flange attached to one end of the stator, and 6 is a pole provided opposite to the permanent magnet. It's teeth. FIG. 4 is a perspective view of the outer yoke, and the outer yoke 7 has a plurality of pole teeth 6 arranged in the circumferential direction. FIG. 5 is a perspective view of the inner yoke, and the inner yoke 8 has a plurality of pole teeth 6 arranged in the circumferential direction like the outer yoke.

The stator is constructed by combining one outer yoke and one inner yoke.

FIG. 1 is a diagram showing the manufacturing process of an outer yoke according to the present invention, in which 101 is a die of a forging die, 102 is a punch of a forging die, and 103 is a raw material. The die 101 is formed in a shape that transfers the shape of the outer yoke shown in FIG. 4, and the die pole teeth 104 are arranged in the circumferential direction similarly to the outer yoke shown in FIG. The manufacturing process in the figure shows closed die forging,
FIG. 1(a) shows the state in which the raw materials are set. The raw materials are
The ring shape is approximately the same size as the outer diameter of the outer yoke and the inner diameter of the pole teeth. FIG. 1(b) is a diagram showing the forging state, in which the raw material 103 is pushed by the punch 102 and flows along the shape of the die, forming an outer yoke shape.

Since the flow of the raw material is not regulated in the downward direction shown in the figure, variations in the so-called raw material volume, such as the plate thickness of the raw material, become variations in the height in the pressurizing direction. Therefore, the minimum height in forging is made higher than the height of the pole teeth and outer circumference of the stator. FIG. 1(c) shows the outer yoke after forging, and the pole teeth are cut along the a-a line and the outer shape is cut along the bb'' line to obtain the outer yoke shown in FIG. 4.

The inner yoke is also manufactured in the same manner as the outer yoke described above. FIG. 2 is a diagram showing the manufacturing process of the inner yoke according to the present invention, in which 101 is a die of a forging die, 102 is a punch of a forging die, and 103 is a raw material.

FIG. 2(a) shows the state in which the raw materials are set. Figure 2 (
b) shows the forged state, where the raw material 103 is pressed by the punch 102, flows along the shape of the die 101, and forms the shape. Next, the inner yoke shown in FIG. 5 is obtained by cutting the pole teeth of the forged inner yoke shown in FIG. 2(C) along the line CC=.

The pole teeth and outer periphery of the outer yoke and inner yoke can be cut by press working, turning with a lathe, etc., and either of these methods can be used in combination or alone.

FIG. 3(a) is a cross-sectional view of the pole teeth of the stator manufactured by the manufacturing method of the present invention. It can be made larger than that. In addition, the shape of the pole tooth and the thickness of the root of the pole tooth can be freely selected, and in addition to the shape shown in Fig. 3 (a), shapes such as (b) and (C) in Fig. Manufacturable. In addition, as shown in FIG. 3(C), if the stator plate thickness and the pole tooth plate thickness are equal and the problem of magnetic saturation can be ignored, it is possible to manufacture such a shape.

In the manufacturing method of the present invention, closed die forging has been explained, but it goes without saying that other methods such as a free forging method using an open die or a method intermediate between a closed die forging method and a free die forging method are also possible. It is possible.

[lf! As described above, according to the present invention, by manufacturing the stator of a stepping motor using a forging method, the stator becomes a continuous fiber structure, improving mechanical properties and imparting mechanical strength to the pole teeth. Not only does it have an excellent dimensional sheath layer with no pole tooth sharpness, but also the shape of the pole teeth can be manufactured in a shape that does not cause magnetic saturation, making it possible to increase the division and speed of stepping motors. Furthermore, since this method is excellent in productivity, it has the effect of being able to provide information equipment users with inexpensive, high-performance motors and contributing to the development of information equipment.

[Brief explanation of drawings]

Figures 1 and 2 are manufacturing process diagrams of the present invention, and Figure 3 is
FIG. 4 is a perspective view of the outer yoke, and FIG. 5 is a cross-sectional view of the pole teeth.
FIG. 6, a perspective view of the inner yoke, is a cross-sectional perspective view of the PM stepping motor. 1... Stator 2... Permanent magnet 3... Motor shaft 4... Coil 5 ・ 6 ・ ・ 7 ・ Flange pole tooth Outer yoke Inner yoke Die Punch Raw material Die pole tooth and above Applicant Seiko Epson Corporation Representative Patent Attorney Kisanbe Suzuki 1 person (g) <C) Fig. 1 (Fig. 2) Zu 2 anger 4 people 3 hair-ν 1 illusion 4 yirumi, fuunn'' b hand divided figure 6

Claims (1)

[Claims] 1. A method for manufacturing a stator for a stepping motor, characterized in that a stator for a PM stepping motor having a plurality of pole teeth arranged in the circumferential direction is formed by press forging.