JPH0965621A - Method of manufacturing stator yoke for motor - Google Patents

Abstract

(57) An object of the present invention is to make the length of a magnetic pole piece with respect to an inner diameter of a motor as long as necessary, and to make it possible to arbitrarily change the shape of the tip end portion of the magnetic pole piece. A method for manufacturing a motor stator yoke having a structure in which a plurality of tooth-shaped magnetic pole pieces (16) project from an inner peripheral edge of an annular plate-shaped portion (14) in parallel to an axial direction, and these are continuously integrated. is there. A plurality of magnetic poles are formed by a step of forming a cylindrical body 12 having an end face closed structure by expanding a central portion of a plate-like body 10 made of a magnetic material by drawing and punching the closed end face 12a of the cylindrical body. By forming the tip end portion 16a of the piece and shearing the peripheral wall portion 12b of the cylindrical body in the axial direction, the base portion 16b of the pole piece that is continuous with the tip end portion of the pole piece formed in the previous step is cut out. The steps and the step of shaping the pole piece 16 by bending at a substantially right angle so as to cause the tip of the pole piece are performed in this order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a stator yoke for a small motor. More specifically, the magnetic plate-like body is formed into a cylindrical body having an end face closed structure by drawing, and the cylindrical shape is obtained. The present invention relates to a method for cutting out a pole piece by punching a closed end surface of a body and axially shearing a peripheral wall portion, and shaping the pole piece by bending a tip portion. This technique is useful, for example, for manufacturing a stator yoke for an inner rotor type stepper motor having a structure in which a plurality of tooth-shaped magnetic pole pieces are arranged in parallel on the inner peripheral portion.

[0002]

2. Description of the Related Art As is well known, an inner rotor type stepper motor comprises a combination of a stator portion and a rotor portion rotatably supported inside thereof. In a typical example, the stator part is mainly composed of an outer yoke, an inner yoke, and an annular coil interposed between them, and two sets of these are connected. The inner yoke has a structure in which a plurality of tooth-shaped magnetic pole pieces are projected from the inner peripheral edge of the annular plate-shaped portion in parallel to the axial direction at equal intervals, and are continuously integrated. The outer yoke has an outer peripheral tubular portion continuous with the outer peripheral edge of the annular plate-shaped portion,
In addition, a plurality of tooth-shaped magnetic pole pieces project from the inner peripheral edge of the annular plate-shaped portion in parallel to the axial direction at equal intervals, and these are continuously integrated. The inner yoke and the outer yoke are combined in such a manner that their tooth-shaped magnetic pole pieces are in conflict with each other,
The coil is sandwiched between. The two sets of the combined body are combined such that the inner yokes are back to back and the tooth-shaped magnetic pole pieces are displaced by ¼ of the angle between the magnetic pole pieces. The rotor portion, which is rotatable by bearings in the stator portion, is composed of a shaft, a multi-pole magnetized annular permanent magnet fixed to the shaft, and the like. This stepper motor is configured to be rotationally displaced stepwise by a magnetomotive force generated by supplying a pulse current to the coil.

The simplest method for manufacturing a stator yoke in which a plurality of tooth-shaped magnetic pole pieces are axially projected on the inner peripheral edge of the annular plate-shaped portion as described above is a pulling-out method. This is a method in which a plate-shaped body made of a magnetic material is punched into the shape of a tooth-shaped magnetic pole piece and then bent at a substantially right angle so as to cause it. However, this method has a problem that the tooth-shaped magnetic pole piece cannot be elongated with respect to the motor inner diameter (in other words, the inner diameter of the annular plate-shaped portion).

Therefore, various methods have been developed for manufacturing long pole pieces. For example, a plate-shaped body is expanded to form a cylindrical body with an end face closed structure by swelling the central portion, and the entire end face is removed to form a cylindrical body with an open end face. There is a method of cutting out a long rectangular pole piece by shearing in the axial direction (see Japanese Patent Laid-Open No. 56-86054). As still another example, after the plate-shaped body is bulged into a trapezoidal shape or a hemispherical shape, the bulging-formed portion is punched out to punch it in correspondence with the formation of the taper-shaped magnetic pole piece, and the punched portion is bent. Method (JP-A-57-21)
1964).

[0005]

Of the above-mentioned conventional techniques,
The former method requires a high level of technology because the shearing process is performed over the entire length of a long pole piece, which requires a long machining time per piece, and has a problem that only a rectangular tooth-shaped pole piece can be obtained. On the other hand, although the latter method is excellent in productivity, it is possible to perform bulging only to the extent that punching is possible, and there is a limit to how long the tooth-shaped magnetic pole piece can be.

An object of the present invention is to provide a stator yoke for a motor in which the length of the pole piece with respect to the inner diameter of the motor can be made as long as necessary and the shape of the tip of the pole piece can be arbitrarily changed. It is to provide a manufacturing method.

[0007]

DISCLOSURE OF THE INVENTION The present invention is for a motor having a structure in which a plurality of tooth-shaped magnetic pole pieces are projected from an inner peripheral edge of an annular plate-shaped portion in parallel to the axial direction, and these are continuously integrated. It is a method of manufacturing a stator yoke. Here, a feature of the present invention is that a plate-shaped body made of a magnetic material is drawn to expand a central portion thereof to form a cylindrical body having an end face closed structure, and the closed end face of the cylindrical body is punched. To form the tips of a plurality of pole pieces, and to perform the axial shearing process on the peripheral wall of the cylindrical body so that the base of the pole pieces is continuous with the tips of the pole pieces formed in the previous step. It is characterized in that the step of cutting out and the step of shaping the pole piece by bending at a substantially right angle so as to cause the tip of the pole piece are performed in this order.

Further, according to the present invention, the outer peripheral cylindrical portion is continuous with the outer peripheral edge of the annular plate-shaped portion, and a plurality of tooth-shaped magnetic pole pieces project from the inner peripheral edge of the annular plate-shaped portion in parallel to the axial direction. It is a method of manufacturing a motor stator yoke having a structure in which the stator yokes are installed and integrated continuously. In that case, a plate-like body made of a magnetic material is subjected to a drawing process to bend the outer peripheral tube portion, and at the same time, to bulge the central portion to form a cylindrical body having a short-face closed structure in the same direction as the outer peripheral tube portion. . After passing through this drawing process, the tooth-shaped magnetic pole pieces are shaped by the same processes as described above.

The shape of the tip of the pole piece can be any shape such as a triangular shape, a trapezoidal shape, or a semi-elliptical shape depending on the shape of the punching die. On the other hand, the base of the pole piece has a rectangular shape to undergo shearing. The closed end surface of the cylindrical body before punching is
The shape is almost flat.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, of the cylindrical body formed by drawing, both the closed end face and the peripheral wall portion are used as pole pieces. Since the closed end surface is punched out, a pole piece tip having an arbitrary shape can be formed. Since the peripheral wall of the cylindrical body is sheared in the axial direction to cut out the base of the pole piece, the length is not particularly limited. As long as the cylindrical body can be formed by drawing, the base of the long pole piece can be obtained. The distance for shearing is shortened by the amount of punching, and shearing becomes easier.

[0011]

FIG. 1 is a process explanatory view showing an example of a method for manufacturing a stator yoke for a small motor according to the present invention. This is a stator yoke having a structure in which a plurality of tooth-shaped magnetic pole pieces project in parallel to the axial direction from the inner peripheral edge of the annular plate-shaped portion and are continuously integrated (that is, equivalent to the inner yoke shown in the above-mentioned known example). It is a method of manufacturing a stator yoke having a shape.

First, a plate-like body 10 made of a magnetic material as shown in FIG. 1A is expanded at its central portion by drawing to form a cylindrical body 12 having an end face closed structure as shown in FIG. 1B. As shown in FIG. 2, the cylindrical body 12 includes a closed end surface 12a having a substantially flat shape and a peripheral wall portion 12b. At this stage, the outer periphery of the plate-shaped body 10 is trimmed as needed to form the annular plate-shaped portion 14.

Next, as shown in FIG. 1C, the cylindrical body 1
The two closed end faces 12a are punched in the axial direction to form the tip portions 16a of the plurality of magnetic pole pieces. Here, the tip end portion 16a of each magnetic pole piece has a triangular shape.
This punching process can be accurately and easily performed by using a die having a predetermined shape (here, the front end surface is a five-valve flower-shaped punch). Subsequently, as shown in D of FIG. 1, the peripheral wall portion 12b of the cylindrical body 12 is axially sheared so that the tip end portions 16a of the magnetic pole pieces punched out in the previous step.
The base portion 16b of the magnetic pole piece is cut out so as to be continuous. In this shearing process, a punch having a cutting edge with an acute angle with respect to the central axis is used so that the magnetic pole piece is pressed down toward the annular plate-shaped portion.

Finally, as shown in FIG. 1E, the tip portion 16a of the pole piece is raised and bent so as to be substantially in the same plane as the base portion 16b, and the pole piece 16 is shaped.
The annular plate-shaped portion 14 may be trimmed at a stage after the shaping of the magnetic pole pieces, instead of the step B of FIG. As a result, a plurality of (five in this case) tooth-shaped magnetic pole pieces 16 project from the inner peripheral edge of the annular plate-shaped portion 14 in parallel to the axial direction at equal intervals, and these are integrated continuously. A stator yoke is obtained.

The tip of the tooth-shaped magnetic pole piece obtained in the above embodiment was triangular, but according to the method of the present invention, an arbitrary magnetic pole can be obtained by changing the shape of the die for punching. One tip shape can be realized. An example thereof is shown in FIG. In the example shown in FIG. 3A, the tip of the pole piece has a trapezoidal shape, and the base has a rectangular shape. Further, in the example shown in FIG. 3B, the tip of the pole piece has a semi-elliptical (semi-elliptical) shape, and the base has a rectangular shape. Not limited to these, it is possible to manufacture a tooth-shaped magnetic pole piece having an arbitrary tip shape. Such a tapered tip shape is useful for suppressing magnetic saturation at the base of the pole piece and increasing magnetic efficiency.

When manufacturing a stator yoke corresponding to the outer yoke in the known example, the steps shown in FIG. 4 are performed. First, as shown in FIG. 4A, a plate-shaped body 20 made of a magnetic material is prepared. Next, this plate is drawn and
As shown in FIG. 4B, the outer peripheral cylinder portion 21 is formed and the central portion is inflated to form the cylindrical body 22 having the end face closed structure in the same direction as the outer peripheral cylinder portion 21. For example, a plate-like body may be first drawn into a dish shape, the central portion may be deeply drawn into a bowl shape, and the center of the bottom portion may be gradually raised inward to form a cylindrical shape. After that, the edge of the outer peripheral tubular portion 21 is trimmed as needed. The cylindrical body 22 formed by this drawing has an end face closing structure including a closed end face 22a and a peripheral wall portion 22b. As a result, the outer peripheral cylindrical portion 21
An annular plate-shaped portion 24 is formed between the cylindrical body 22 and the central cylindrical body 22.

The following steps may be basically the same as in the above embodiment. As shown in FIG. 4C, the closed end surface 22a of the cylindrical body 22 is punched (the processing position and the processing direction are indicated by arrows W ₁ ) to form the tip portions 26a of the plurality of magnetic pole pieces. Then, as shown in FIG. 4D, the peripheral wall portion of the cylindrical body is sheared in the axial direction (the processing position and the processing direction are indicated by an arrow W ₂ ), whereby the tip end portion 26 a of the magnetic pole piece punched out in the previous step. The base portion 26b of the magnetic pole piece that is continuous with the above is cut out. Finally, as shown in FIG. 4E, the pole piece 26 is shaped by bending the tip end portion 26a of the pole piece and bending it substantially at right angles so that the tip end portion 26a is in the same plane as the end portion 26b. Therefore, after forming into a predetermined shape by drawing, the method of forming the pole pieces is exactly the same as that shown in FIG.

In this manner, the outer peripheral cylindrical portion which is continuous with the outer peripheral edge of the annular plate-shaped portion, and a plurality of tooth-shaped magnetic pole pieces project from the inner peripheral edge of the annular plate-shaped portion in parallel to the axial direction. Set up,
A stator yoke having a structure in which they are continuously integrated is obtained.

In carrying out the method of the present invention, independent plate-shaped bodies may be prepared and subjected to drawing, punching, shearing and bending. It is also possible to employ a system in which drawing, punching, shearing, and bending are sequentially performed without separating them one by one, and the individual stator yokes are also separated by finally performing trimming as well.

[0020]

As described above, according to the present invention, the magnetic pole piece is cut out by combining the punching process and the axial shearing process, so that the magnetic pole length can be made large with respect to the motor inner diameter. Since the length required for the shearing process is shortened by the amount of punching, the work is easy without requiring a high level of processing technology, and the processing time per piece can be shortened. Moreover, since the tip portion is punched out, an arbitrary shape such as a triangular shape or a trapezoidal shape can be realized according to the shape of the mold.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing one embodiment of the method of the present invention.

FIG. 2 is a sectional view showing the shape of a molded product after drawing.

FIG. 3 is an explanatory view showing a shape example of a magnetic pole piece obtained by the method of the present invention.

FIG. 4 is a process explanatory view showing another embodiment of the method of the present invention.

[Explanation of symbols]

 10, 20 Plate-like body 12, 22 Cylindrical body 12a, 22a Closed end face 12b, 22b Circular wall part 14, 24 Annular plate-like part 16, 26 Magnetic pole piece 16a, 26a Magnetic pole piece tip 16b, 26b Magnetic pole piece base 21 Outer peripheral cylinder

Claims (3)

[Claims] 1. A method for manufacturing a motor stator yoke having a structure in which a plurality of tooth-shaped magnetic pole pieces project from an inner peripheral edge of an annular plate-shaped portion in parallel to the axial direction and are continuously integrated. Then, a plate-shaped body made of a magnetic material is drawn to swell the central part to form a cylindrical body with an end face closed structure, and the closed end face of the cylindrical body is punched to form a plurality of magnetic pole pieces. The step of forming the tip of the pole piece and the step of cutting the base of the pole piece that is continuous with the tip of the pole piece formed in the previous step by shearing the peripheral wall of the cylindrical body in the axial direction. A method of manufacturing a stator yoke for a motor, which comprises bending the magnetic pole pieces at a substantially right angle so as to cause the tips of the pieces and shaping the pole pieces in this order. 2. A plurality of tooth-shaped magnetic pole pieces protruding from the inner peripheral edge of the annular plate-shaped portion in parallel to the axial direction, the outer peripheral cylindrical portion continuing to the outer peripheral edge of the annular ring-shaped portion, A method of manufacturing a motor stator yoke having a structure in which they are continuously integrated, in which a plate-shaped body made of a magnetic material is drawn to form an outer peripheral cylinder portion and a central portion is bulged to form a cylinder with an end face closed structure. A step of forming the cylindrical body in the same direction as the outer peripheral cylinder part, a step of punching the closed end surface of the cylindrical body to form the tips of a plurality of magnetic pole pieces, and the peripheral wall part of the cylindrical body. By cutting the base of the pole piece that is continuous with the tip of the pole piece formed in the previous step by shearing in the direction, and bending the pole piece approximately at a right angle to cause the tip of the pole piece. The order of shaping Method of manufacturing a motor stator yoke and performing. 3. A cylindrical body formed by drawing,
The manufacture of a stator yoke for a motor according to claim 1 or 2, wherein the closed end surface has a substantially flat shape, and the closed end surface is punched to form a triangular, trapezoidal, or semi-elliptical pole piece tip. Method.