JPH08340660A - Stepping motor yoke molding method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a method for forming a yoke of a stepping motor, after forming a magnetic material plate by press punching,
Since a rotating tool is used in the prior art when finishing the shape of the pole teeth, a large burr is generated, and a step for removing the burr is required. Further, when a rotating tool having a small radius is used so that burrs do not occur, the area of the tip surface of the pole tooth cannot be increased. SOLUTION: A yoke of a rotor or a stator of a stepping motor having pole teeth is formed by press punching, and a plurality of magnetic material plates are pressure-laminated in the same direction, and then the pole teeth are punched out. The surface is finished by shaving from the direction opposite to.

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 a yoke of a stator or a rotor of a stepping motor.
In particular, it relates to a method for finishing the pole tooth surface formed on the yoke.

[0002]

2. Description of the Related Art The structure of a typical stepping motor which has been conventionally used is shown in FIG. In the figure, the stator 2
Is composed of a stator laminated body yoke formed by stacking a plurality of magnetic material processed into the same shape by press working, and a coil 1 wound by a predetermined number on the stator laminated body yoke. In the stator laminate yoke,
The stator pole teeth 2a are formed to face the rotor 5, and a reference surface 2b for fixedly supporting the rotor case 3 is formed on the opposite side thereof. The rotor 5 is composed of a rotor magnet and a rotor laminated body yoke, and the reference surface 5 b for fixing to the shaft 4 and the rotor pole teeth 5 a are the stator pole teeth 2.
It is formed so as to face a.

In the stepping motor having such a structure, the gap 6 between the stator pole teeth 2a and the rotor pole teeth 5a is required to intermittently rotate and stop the shaft 4 as an output shaft at an accurate angle. It is necessary that the entire circumference be uniform regardless of the rotational position of the rotor 5.
Further, the gap 6 needs to be as small as possible in order to reduce the input current to the coil 1 and increase the holding torque and the rotation torque to be output to the shaft 4.

As shown in FIG. 7, the stator pole teeth 2a and the rotor pole teeth 5a are basically formed in a short tooth shape. The left and right tip corners 7 concentrate the magnetic flux density,
In order to increase the torque and reduce the fluctuation of the stop angular position, it is necessary to form the shape sharply.

Further, since the tip surfaces 8 of the stator pole teeth 2a and the rotor pole teeth 5a shown in FIG. 8 are the facing areas between the pole teeth, it is desired that the surface area be as large as possible and the surface roughness be as small as possible. As described above, the shape of the tip of the pole teeth greatly affects the performance of the stepping motor. Therefore, in order to minimize the gap between the pole teeth of the rotor and the stator, the pole teeth should be shaped so that the tip surfaces of each pole tooth are vertical and the surface roughness is small. Must be formed so as to face each other in parallel with the gap of. Further, in order to increase the facing area, the tip corner 7 must be formed as sharp as possible.

Next, a method of forming a laminated yoke of a general stator and rotor will be described in the order of steps. (1) A raw material that is a magnetic material is press-pressed to continuously form blank plates, which are laminated and fixed. (2) In order to increase the stacking fixing force and remove the stacking gap, press working from above and below. (3) Since there is a slight deviation in the stacking position and the surface roughness of the punched surface is poor when the press-punched stacking is fixed, the reference surface that serves as the position reference of the pole teeth is finished by cutting or grinding.
(4) Using the reference surface as a reference, the pole tooth tip corner R is removed, the pole tooth tip surface roughness is improved, and the pole tooth tip surface is finished by grinding with a rotary tool in order to remove a minute stacking misalignment. do. (5) The return of the pole tooth tip corner generated in the pole tooth finishing is removed by brushing or the like. In addition, the secondary pressurizing step (2) may be a continuous processing that is included in the step (1), and the steps (3) and (4) may be performed in reverse, and the pole tooth reference surface processing is performed after the pole tooth tip surface processing. In some cases.

The step (4) will be described in more detail with reference to FIGS. 9 to 13. FIG. 9 is a view of the laminated body yoke immediately after the press drawing is viewed from the axial direction, FIG. 10 is a cross-sectional view in the direction along the radius thereof, and FIG. 11 is a view of the pole tooth tip viewed from the radial direction. . As shown in FIG. 9, the tip corners 7 of the pole teeth immediately after being formed by press punching are not sharp edges, but large Rs are formed. Further, as shown in FIG. 10, the tip surface 8 also has a surface sag 9, and a vertical flat surface is not formed. Therefore, as shown in FIG. 11, the vertical plane portion of the tip surface 8 is very small.
Therefore, finishing is performed to adjust the shape of the tip of the pole tooth and increase the vertical plane portion of the tip surface 8. Conventional finishing processing has been performed using a rotary tool that rotates coaxially with the rotation axis of the motor.

12 and 13 show the tip surface 8 after finishing with a rotary tool. FIG. 12 shows a case where the radius of the rotary tool is small, and grinding is carried out with a radius shown by a dotted line A in FIGS. 9 and 10, and FIG. 13 shows a case where grinding is carried out with a large radius shown by a dotted line B. As shown in FIG. 12, when grinding is performed with the radius of the dotted line A, the burr 10 is small, but since the surface sag 9 and the R of the tip corner 7 are not completely removed, the area of the vertical plane portion of the tip surface 8 is small. Is small. On the other hand, as shown in FIG. 13, when grinding with a large radius B, the area of the vertical plane portion of the tip surface 8 can be increased, but the burr 10
Becomes large, and the motor performance is not improved unless the burr 10 is sufficiently removed.

[0009]

[Problems to be Solved by the Invention] As described above,
In the past, since the tip surface of the pole tooth was press-punched and then surface-finished with a rotary tool, when cutting with a large radius to remove the surface sag, large burr occurs,
Another step was required to remove this burr. Further, there is a problem that the area of the plane portion perpendicular to the tip face cannot be sufficiently increased by cutting with a rotary tool having a small radius in order to reduce the burr. The object of the present invention has been made in view of the above circumstances, and provides a method for finishing a laminated body yoke in which the area of the vertical flat surface of the tip surface of the pole tooth can be made sufficiently large and burr does not occur at all. The purpose is to

[0010]

In order to achieve the above object, the present invention provides a method for forming a yoke of a stepping motor having pole teeth, in which a plurality of magnetic material plates formed by press punching are used. It is characterized in that the surface of the pole teeth of the laminated body yoke, which is pressure-laminated in the same direction as the press-out direction, is finished by shaving from the direction opposite to the press-out direction.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. As described above, the pole teeth portion of the laminated body, which has been press punched from above and laminated and fixed, before being shaving is formed in the shape shown in FIGS. 9 and 11. FIG. 1 is a longitudinal cross-sectional view of an essential part showing a state where the tip surface of a pole tooth according to the present invention is finished by shaving.
In the figure, the shaving direction of the laminated body yoke 11 is opposite to the press contour drawing direction, and is therefore opposite to the surface sagging direction. The laminated body yoke 11, which is a stator or a rotor, is positioned on the die 13, the upper die is lowered, and the work pusher 14 fixes the laminated body yoke 11 first. The work pusher 14 has its back portion biased by a compression spring, and presses the laminated body yoke 11 during the shaving process against the die 13. As the lower die advances, the punch 12 fixed to the upper die finishes the outer and inner diameters of the laminated body yoke 11 by shaving.

2 and 3 respectively show the cross section and the tip end face of the pole tooth after the shaving finishing process by the method shown in FIG. As shown in FIG. 2, the surface sag is cut and simultaneously plastically deformed and corrected by shaving from the opposite direction. Therefore, as shown in FIG. 3, the tip surface 8 has the maximum area, which corresponds to the cross-sectional area of the magnetic material plate. The tip corner 7 is also a straight line. 4 and 5, for reference, without reference to the present invention,
It shows a case where shaving finish is performed in the same direction as the surface sag. Although the cutting amount is the same as in FIGS. 3 and 4, the surface sag is not corrected and the area of the tip surface 8 is not sufficient. Further, it can be seen that the tip corner 7 is also discontinuous.

[0013]

As is apparent from the above description, according to the present invention, the surface finish of the pole teeth of the magnetic base plate of the yoke of the stepping motor formed by press punching is applied to a plurality of magnetic base plates. In the pressure-laminated state, the tip surfaces of the pole teeth are made to have a large vertical area by performing the shaving process in the direction opposite to the press-extracting direction, and the motor performance can be improved. Further, unlike the conventional case, since a large burr is not generated, the deburring step is not necessary, so that the production cost can be reduced.

[Brief description of drawings]

FIG. 1 is a shaving finishing cross-sectional view for explaining a finishing process according to the present invention.

FIG. 2 is a sectional view of a pole tooth in the same direction shaving as in the press contour cutting for explaining a finishing step according to the present invention.

FIG. 3 is a front view of the tip of a pole tooth in the same direction shaving as in the press contour cutting for explaining the finishing step according to the present invention.

FIG. 4 is a cross-sectional view of a pole tooth in the press shaving and reverse direction shaving for explaining the finishing process according to the present invention.

FIG. 5 is a front view of the tip of a pole tooth in the press shaving and reverse direction shaving for explaining the finishing step according to the present invention.

FIG. 6 is a structural cross-sectional view of a general stepping motor.

FIG. 7 is a plan view of pole teeth of a stator yoke and a rotor yoke of a general stepping motor.

FIG. 8 is a perspective view of pole teeth of a yoke of a general stepping motor.

FIG. 9 is a plan view of the pole teeth of the yoke after the press outer shape is removed.

FIG. 10 is a cross-sectional view of the pole teeth of the yoke after the press outer shape is removed.

FIG. 11 is a plan view of the tip surface of the pole teeth of the yoke after punching the outer shape of the press.

FIG. 12 is a plan view of a tip surface of a pole tooth formed by a conventional finishing method.

FIG. 13 is a plan view of the tip surface of a pole tooth formed by a conventional finishing method.

[Explanation of symbols]

 2a Stator pole teeth 5a Rotor pole teeth 7 Tip corner 8 Tip surface 9 Surface sag 10 Burr 11 Laminated yoke 12 Punch 13 Die

Claims (1)

[Claims] 1. A method of forming a yoke of a stepping motor having pole teeth, wherein a plurality of magnetic material plates formed by press punching are laminated under pressure by laminating in parallel with each other in a press punching direction. The step of forming the yoke of the stepping motor is characterized in that the surface finishing is performed by shaving from the direction opposite to the direction of pressing.