JP3069932B2 - Stepping motor yoke molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming and manufacturing a yoke as a component of a stepping motor from a metal plate.

[0002]

2. Description of the Related Art A stepping motor is a motor for converting an electric pulse signal into a step-like (intermittent) operation of mechanical intermittent operation, such as paper feed and space feed in a printer, and driving of a magnetic head in a floppy disk device. It is widely used today in various fields of electronic equipment.

In this stepping motor, for example, a thin cylindrical permanent magnet is mounted on the outer periphery of the rotor, and the magnet has multiple poles (5 to 5 poles).
24 are arranged on the outside of the rotor, and four yokes having pole teeth equal to the number of magnetizations of the rotor are arranged outside the rotor as shown in FIG. And the motor is 2
The rotating magnetic field generated by sequentially switching the currents flowing through the individual coils causes the shaft fixed to the rotor axis to rotate intermittently, and the motor outer diameter is as small as 5 to 30 mm. It is easy to electronically control and excellent in gear down / gear up, forward / reverse rotation switching, speed change, instantaneous stop function, etc., so that it is indispensable to the above electronic devices.

When a yoke for a stepping motor requiring such small size and precision is manufactured from a metal plate, it is conventionally manufactured by steps shown in FIGS.

That is, a metal plate 1 is first drawn by a press machine to form a hemispherical recess 2 having a predetermined diameter corresponding to the inner diameter of the yoke (FIG. 8). In order to leave the same number of pole teeth 3 of the same width, punching 4a is performed in a substantially triangular shape at equal intervals with a punch, and the center of the depression 2 is punched 4b to form the poles once as shown in FIG. Next, each pole tooth 3 is bent so as to stand up (FIG. 1).
0), the outer peripheral portion is punched to form a donut-shaped brim 5 along the base of the pole teeth 3 to obtain a yoke A as a finished product as shown in FIG.

However, in the conventional yoke molding, since the pole teeth 3 are manufactured from the two surfaces of the above-mentioned depressions which become the inner diameter of the yoke, the length of the teeth is restricted, and it is technically difficult to take a large number of teeth. Stepping that requires precision, such as making each pole tooth 3 thinner toward the tip and making it impossible to obtain a tooth having a uniform thickness by drawing in forming the depression 2 In motors, the quality of the production of the yoke has influenced the performance of the yoke.

[0007]

SUMMARY OF THE INVENTION The present invention solves the problems of the yoke according to the conventional manufacturing method as described above. The length of the pole teeth can be freely increased, and the thickness of the teeth is uniform. It is intended to propose a method capable of easily forming a number of pole teeth.

[0008]

That is, according to the present invention, the pole teeth are not obtained from the depression 2 obtained by drawing on a metal plate as in the prior art. Is punched out, and the pole teeth 3 are taken from the metal plate portion outside the recessed portion. Hereinafter, examples of the method of the present invention will be described with reference to FIGS.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a metal sheet 1 is subjected to a first drawing process by a press machine so that an outer diameter becomes a yoke inner diameter once so as to form a substantially trapezoidal recess 2a having a substantially vertical cross section (FIG. 1). Then, secondary drawing is performed to widen the bottom surface of the depression 2a so as to be the same as the upper surface diameter, thereby forming a short bottomed cylindrical depression 2b (FIG. 2).

Next, the above-mentioned recess 2b is punched in the metal plate 1 radially around the recess 2b so as to leave a portion having a predetermined length, width and number of pole teeth 3 as shown in FIG. Get B.

Next, the bottom surface 6 of the dent 2b remaining in the semi-finished product B is dropped by punching, and bent so that the horizontal pole teeth 3 are erected (FIG. 4).

Next, in order to form the peripheral side portion 7 of the depression 2b remaining at the base of the pole teeth 3 into a brim shape, the peripheral side portion 7 is once expanded into a skirt shape 7a (FIG. 5), and the portion 7a is finally flattened. The flange 7b is punched (FIG. 6). Finally, the outer peripheral edge 7c of the flange 7b is punched out to leave the collar 5 in a donut shape, and a yoke A as a completed product as shown in FIG.
You get

The bottom 6 of the recess 2b can be punched immediately after the formation of the recess 2b before the semi-finished product B is collected, or simultaneously with the punching and collecting of the semi-finished product B.

[0014]

The yoke forming method of the stepping motor according to the present invention is as described above, and the recessed portion formed in the metal plate as the inner diameter of the yoke is different from the related art in any respect to the formation of the pole teeth. Since each pole tooth is formed by a metal plate part outside the recessed part, not by the part, the length of the tooth can be freely set without restriction on the length of the tooth, and the number of teeth can be easily obtained more than before. In addition, the tooth thickness is uniform from the base to the tip.

Therefore, according to the method of the present invention, there is an advantage that a yoke corresponding to various precision and ultra-small stepping motors can be easily manufactured, and the accuracy of the motor can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a first drawing process for a metal plate in a method of forming a yoke for a stepping motor according to the present invention.

FIG. 2 is an explanatory view showing a second drawing process.

FIG. 3 is an explanatory view showing a state in which a semi-finished product yoke B is punched.

FIG. 4 is an explanatory view showing a process of raising and bending a pole tooth and extracting a bottom.

FIG. 5 is an explanatory view showing one process of forming a brim on a peripheral portion of the pole tooth base.

FIG. 6 is an explanatory diagram showing a state at the time when the brim out is completed.

FIG. 7 is a finished product yoke A in which the outer periphery of the brim is also punched out.
It is explanatory drawing which shows the state which collect | recovers.

FIG. 8 is an explanatory view showing a first drawing process in a conventional yoke forming method for a stepping motor.

FIG. 9 is an explanatory view showing one process of forming pole teeth.

FIG. 10 is an explanatory view showing a state where the pole teeth are raised and bent.

FIG. 11 is an explanatory view showing a state in which the finished product yoke A is recovered by punching the outer periphery of the pole teeth from a metal plate.

[Explanation of symbols]

 A-Finished product yoke B-Semi-finished product yoke 1-Metal plate 2-Depression 3-Tooth 4-Stamping part 5-Collar 6-Depression bottom 7-Depression peripheral side

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 37/14

Claims (1)

(57) [Claims] 1. A method for forming a yoke of a stepping motor in which a plurality of pole teeth are erected on an inner peripheral edge of a donut-shaped brim, wherein a bottomed cylindrical recess having a diameter equal to the inner diameter of the yoke is formed in a metal plate by drawing. Then, a part having the predetermined length, width, and number of pole teeth radially centered on the depression is punched and collected from a metal plate integrally with the depression, and then the bottom of the depression of the recovered material is removed. A method for forming a yoke for a stepping motor, comprising punching and bending each pole tooth portion, and then punching out the peripheral portion of the depression to remove the outer peripheral edge portion.