JPH07186201A - Molding die for steeping motor rotor and rotor molded by this die - Google Patents

Abstract

PURPOSE:To prevent the angular part of a die from chipping when assembling the die into a device by connecting one end side, of a gradient surface provided on an angular part between a die surface forming the external periphery of the die and a die surface forming an end surface, which connects to the die surface forming the external periphery of the die, and the other end side which connects to the die surface forming an end surface. CONSTITUTION:A die 28 has a die surface 28a and a die surface 28b which form the external peripheral surface 22a and the lower end surface 22 of a magnetic polar part 22 respectively. In addition, a die 29 which forms the internal peripheral surface of the magnetic polar part 22 and the lower surface side of an intermediate collar part 23 and a boss part 24, is counter-positioned against the die 28. Further, an angular part between the die surface 28a and the die surface 28b of the die 28 has a curvature 32 of specified size as a gradient surface. On the die 28, the die surface 28a forming the external peripheral surface 22a of the magnetic polar part 22, and the die surface 28b forming the lower end surface 22b are integrally formed and the angular part is formed like a recessed part with a curvature 32. Thus the die 29 no longer comes into contact with the angular part of the die 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a permanent magnet type stepping motor, and more particularly to a molding die for manufacturing a rotor rotatably supported in a stator, and a rotor molded by this die.

[0002]

2. Description of the Related Art A two-phase permanent magnet type stepping motor (hereinafter simply referred to as a motor) is constructed, for example, as shown in FIG. That is, the motor 1 has a stator 2 and a mold rotor 3 (hereinafter simply referred to as a rotor), and the stator 2 includes a pair of stator yokes 4 surrounding the rotor 3.
5, the main part is composed. Each of the stator yokes 4 and 5 is a combination of two sheet metal parts, has a donut-shaped space for accommodating the exciting coils 6 and 7, and has a portion facing the outer peripheral surface 3 a of the rotor 3. The pole tooth rows 8 and 9 having a claw pole structure are formed.

The rotor 3 is formed of a cylindrical permanent magnet whose magnetic poles are magnetized at a predetermined pitch in the circumferential direction, and a rotor shaft 10 is fixed to the center thereof. The rotor shaft 10 is
Bearing 1 of front flange 11 fixed to stator yoke 4
2 and a bearing (not shown) of the rear flange 13 fixed to the stator yoke 5 so as to be rotatably arranged. In this rotor 3, a metal rotor shaft 10 is set in a magnetic field orientation mold composed of three molds 14 to 16 shown in FIG. 6, and a plastic magnet resin containing a metal such as ferrite or rare earth is used. By injection from the gate 17 of the mold 16 into the molds 14 to 16, it is integrally molded with the rotor shaft 10. Simultaneously with molding, magnetic poles are magnetized at a constant pitch in the circumferential direction on the outer peripheral surface 3a of the rotor 3 to form permanent magnets.

By the way, conventionally, the joint portion of the die 15 with the die 14 is provided with a chamfer 18 as shown in FIG. This chamfer 18 connects the rotor 3 to the stator yoke 4,
This is for preventing the corner portion of the lower end surface 3b of the rotor 3 from colliding with the stator yokes 4, 5 and the like when the rotor 3 is assembled into the rotor 5, and so on.

[Problems to be Solved by the Invention]

However, in the molds 14 and 15 and the rotor 3 molded by the molds 14 and 15,
The chamfer 18 of the die 15 is inevitably a pseudo chamfer having the straight portion 19, and there is a problem that the effect of preventing the corner portion of the rotor 3 from being applied is insufficient. That is, for example, when the chamfer 18 of the mold 15 is made to be a true chamfer as shown by the chain double-dashed line a in FIG. 7, a sharp edge portion 20 is formed in the mold 15, and for example, the mold 15 is molded. When the 14 is assembled, the edge portion 20 of the die 15 is easily hooked. As a result, great care must be taken when assembling the molds 14 and 15.

On the other hand, although the pseudo chamfering 18 can solve the problem of the edge portion 20 of the die 15,
The effect of preventing the corner portions of the rotor 3 from hanging is not sufficient. Because the straight portion 19 causes the lower end surface 3b of the rotor 3 to
Has a corner on the outer peripheral surface 3a side, and when the rotor 3 is inserted into the stator 2, the corner collides with, for example, the pole tooth rows 8 and 9 of the stator yokes 4 and 5. This is because there are things to call. In particular, the outer peripheral surface 3a of the rotor 3
Since the gap between the pole teeth rows 8 and 9 is very small, the pole teeth rows 8 and 9 are likely to collide with each other and also to be easily broken. As a result, magnetized fragments and the like may adhere to the stator yokes 4 and 5 and remain in the motor 1, which may cause quality problems such as abnormal noise.

The present invention has been made in view of the above circumstances, and an object thereof is to reliably prevent the corners of the mold from being hooked at the time of assembling the mold, and to make the rotor angle at the time of assembling the motor. It is an object of the present invention to provide a molding die for a rotor for a stepping motor and a rotor molded by this die, which can obtain a sufficient effect of preventing the parts from being applied.

[0008]

In order to achieve the above object, a molding die for a rotor for a stepping motor according to claim 1 integrally molds a rotor shaft at a center to manufacture a substantially cylindrical rotor. A molding die for molding a rotor outer peripheral surface and one end surface continuous with the outer peripheral surface.
And a second mold that can be brought into contact with and separated from the mold,
An inclined surface is provided at a corner between the mold surface for molding the outer peripheral surface and the mold surface for molding the end surface of the first mold, and one end side of the inclined surface is the outer periphery of the first mold. On the mold surface to mold the surface,
The other end side is characterized by being continuous with the mold surface forming the end face.

Further, in a stepping motor rotor according to a second aspect of the present invention, in a substantially cylindrical rotor having a rotor shaft integrally formed at the center, an inclined surface is provided at a corner connecting an outer peripheral surface and an end surface of the rotor. The one end side of the inclined surface is continuously connected to the outer peripheral surface.

[0010]

According to the molding die for a stepping motor rotor according to the first aspect, the first die is provided with a die surface for forming the outer peripheral surface and one end surface of the rotor, and the die surface is formed. The corners of the mold surface are provided with an inclined surface formed by a round or a true chamfer. Since the one end side of the inclined surface is continuous with the surface that forms the outer peripheral surface of the rotor and is inclined, there is no edge portion at the corner of the first mold, and the mold is reliably hooked when the mold is assembled. To be prevented.

According to another aspect of the rotor for a stepping motor of the present invention, an inclined surface formed by a rounded chamfer or a true chamfer is formed at a corner connecting the outer peripheral surface of the rotor and one end surface of the rotor. Since one end side thereof is inclined and continuous to the outer peripheral surface, there is no straight portion orthogonal to the rotor axis at the corner portion, and the rotor corner portion at the time of motor assembly such as when inserting the rotor into the stator yoke. Crossing is prevented and a sufficient effect of preventing crossing is obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view of a rotor shaft according to the present invention, which is used, for example, in a two-phase permanent magnet type stepping motor shown in FIG. The rotor 3 includes a cylindrical magnetic pole portion 22 having an outer peripheral surface 22a, a lower end surface 22b, an upper end surface 22c, and an inner peripheral surface 22d, and a disk-shaped middle collar formed at an intermediate position in the magnetic pole portion 22 in the longitudinal direction. It is composed of a portion 23 and a boss portion 24 formed on both surfaces of the middle collar portion 23 so as to project in the longitudinal direction. A rotor shaft 25 is attached to the boss portion 24.
As will be described later, the magnetic pole portion 2 is integrally formed and arranged so as to penetrate therethrough.
The outer peripheral surface 22a of No. 2 and the lower end surface 22b, which is one of the end surfaces, have rounded corners 26 as corners.

The molding die for molding the rotor 3 is shown in FIG.
And as shown in FIG. That is, the mold 28 having the mold surface 28a and the mold surface 28b for molding the outer peripheral surface 22a and the lower end surface 22b of the magnetic pole portion 22, respectively.
And a die 29 for forming the inner peripheral surface 22d of the magnetic pole portion 22 and the lower surface sides of the middle flange portion 23 and the boss portion 24, and the die 28, which are arranged so as to face the die 28. An upper end surface 22c and an inner peripheral surface 22d of the magnetic pole portion 22, and a middle collar portion 23.
And a die 30 for molding the upper surface side of the boss portion 24.

The mold 28 and the mold 29 are placed on a base plate 31, and the corners of the mold surface 28a and the mold surface 28b of the mold 28 are enlarged as shown in FIG. A rounded surface 32 having a predetermined size is provided as an inclined surface. The mold 2
Holes 33, 34 into which the rotor shaft 25 is inserted are provided in 9, 30.
Are formed in the mold 30, and the mold 30 has three gates 35 (resin injection ports) at equal intervals in the circumferential direction.
Has been drilled. These molds 28 are processed by an electroforming method.

Next, the rotor 3 using the molds 28 to 30
An example of the molding method and the method of assembling the rotor 3 into the stator 2 will be described. First, as shown in FIG. 2, the mold 28 is set in the mold 29 placed on the base plate 31, and the mold 30 is set in the molds 28 and 29 and assembled. At this time, the die 28 is attached to the outer peripheral surface 22 of the magnetic pole portion 22.
The mold surface 28a for molding a and the mold surface 28b for molding the lower end surface 22b are integrated, and the corners thereof are formed in a concave shape and are provided with the rounded corners 32. There is no risk of the mold 29 coming into contact with the corners. Then, the rotor shaft 25 made of hardened stainless steel or the like is attached to the hole 34 of the mold 30 until the lower end of the rotor shaft 25 contacts the base plate 31.
The rotor shaft 25 from the mold 2 into the hole 33 of the mold 29.
Set within 8-30.

In this state, as shown by the chain double-dashed line B in FIG. 2, plastic magnet resin is injected from the gate 35 of the mold 30 to mold the rotor 3 and the rotor shaft 2
Integrate with 5. At that time, a magnetic field is generated from the mold 28, and the magnetic poles 22 of the molded rotor 3 are magnetized with N and S magnetic poles at a predetermined pitch. Then, the mold 30 is moved upward and pulled out, and thereafter, the lower end surface 22b is pushed up by an eject pin (not shown) so that the magnetic pole portion 22 and the middle flange portion 2 are pushed.
3. The rotor 3 in which the boss portion 24 and the rotor shaft 25 are integrally formed is taken out from the molds 28 and 29.

Then, the lower end surface 22 of the molded rotor 3
The side b is inserted into the pole tooth row 8 of the stator yoke 4 from the rear end side of the stator yoke 4 accommodating the exciting coil 6, that is, from the direction of arrow a in FIG. Insert into the bearing 12 of the flange 11. At this time, since the radius 26 is formed at the corner between the outer peripheral surface 22a and the lower end surface 22b on the insertion side of the rotor 3, the stator yoke 4
Even if it contacts the pole tooth row 8 and the like, the corner portion of the rotor 3 does not engage. Then, the stator yoke 5 accommodating the exciting coil 7 is fitted on the outer periphery of the rear end portion of the rotor 3, and
The rear end of the rotor shaft 25 is inserted into the bearing of the rear flange 13, and the stator yoke 5 is attached. As a result, the rotor 3 and the stator 2 and the like are assembled.

As described above, in the above embodiment, the mold 28 is provided with the mold surface 28a and the mold surface 28b for molding the outer peripheral surface 22a and the lower end surface 22b of the rotor 3, and the corners thereof are rounded 32. Since the edge is not included in the corner because it is subjected to, the corner is formed in a concave shape,
The contact of the mold 29 is avoided, and the mold 2 is assembled when the mold is assembled.
It is possible to reliably prevent the corners of No. 8 from hanging. As a result, the work of assembling the molds 28 to 30 can be easily performed.
Further, a gap between the molds 28 and 29 is prevented from being generated due to the inflow of resin, which facilitates maintenance of the molds 28 to 30. As a result, the reliability of the molds 28 to 30 is improved and the maintenance cost can be reduced. Furthermore,
By processing the mold 28 by the electroforming method, the accurate mold 28 can be easily obtained.

Further, the rotor 3 has a corner portion between the outer peripheral surface 22a and the lower end surface 22b which is the insertion side into the stator yoke 4,
Since the radius 26 is formed, when the rotor 3 is assembled to the stator 2, it is possible to prevent the corner portion of the rotor 3 from colliding against the stator yoke 4 and exerting a sufficient effect of preventing application. . Further, the outer peripheral surface 22 of the rotor 3
a at the position corresponding to the corner between a and the lower end surface 22b.
Since the bonding surfaces of Nos. 8 and 29 are eliminated, it is possible to prevent burrs generated by the bonding surfaces during molding. As a result, it is possible to prevent the occurrence of abnormal noises, defective rotations and the like caused by the magnetized fragments and burrs adhering to the stator yokes 4 and 5, thus improving the quality and reliability of the motor 1. Can be improved.

In the above-mentioned embodiment, the radiuses 32 and 26 are formed on the mold 28 and the rotor 3, but the present invention is not limited to this and may be constructed as shown in FIG. 4, for example. That is, the mold surface 28a of the mold 28 and the mold surface 2
8B, a true chamfer 37 is applied to the corner, and correspondingly, a true chamfer 38 is formed on the corner between the outer peripheral surface 22a and the lower end surface 22b of the rotor 3. Even with this configuration,
The same action and effect as those in the are 32 and 26 are obtained.

Further, in the above embodiment, the corners between the outer peripheral surface and the lower end surface of the magnetic pole portion are rounded, but, for example, by devising the mold structure, the outer peripheral surface of the magnetic pole portion and the other end surface are The corners with the upper end surface, which is, may be rounded or true chamfered. Further, in the above embodiment, the rotor is formed by integrally molding the plastic magnet resin on the rotor shaft, but it may be applied to, for example, a molded rotor in which the rotor shaft and the permanent magnet are connected and fixed by resin. It goes without saying that various changes can be made without departing from the scope of the present invention.

[0021]

As described above in detail, in the molding die of the stepping motor rotor of the present invention and in the rotor molded by this molding die, it is possible to provide inclined surfaces at the corners of the die. Therefore, it is possible to reliably prevent the corner portions of the mold from being hooked when the mold is assembled. Further, the inclined surface of the rotor corner portion has effects such as a sufficient effect of preventing the rotor corner portion from being applied when the motor is assembled.

[Brief description of drawings]

FIG. 1 is a perspective view of a rotor according to the present invention.

FIG. 2 is a sectional view of a molding die for molding the rotor.

FIG. 3 is an enlarged sectional view of part A of FIG.

FIG. 4 is a cross-sectional view of an essential part showing another embodiment of the present invention.

FIG. 5 is a partially cutaway sectional view of a stepping motor common to an embodiment of the present invention and a conventional example.

FIG. 6 is a sectional view of a molding die showing a conventional example.

FIG. 7 is an enlarged sectional view of part B of FIG.

[Explanation of symbols]

 1 ・ ・ ・ ・ ・ ・ Motor 2 ・ ・ ・ ・ ・ ・ ・ ・ Stator 3 ・ ・ ・ ・ ・ ・ Rotor 4,5 ・ ・ ・ Stator yoke 6,7 ・ ・ ・Excitation coil 10, 25 ... Rotor shaft 22 ... Magnetic pole portion 22a .. Outer peripheral surface 22b .. Lower end surface 22c .. Upper end surface 23. ..... Middle collar part 24 ..... Boss parts 26, 32 ..... R 28-30 .... Molds 28a, 28b .. Mold surface 37, 38 ..・ True chamfer

Claims (2)

[Claims] 1. A molding die for integrally molding a rotor shaft in the center to manufacture a substantially cylindrical rotor, wherein an outer peripheral surface of the rotor and one end surface continuous with the outer peripheral surface are molded. A mold surface for molding the outer peripheral surface of the first mold and a mold surface for molding the end surface of the first mold; An inclined surface is provided at the corner portion of the mold, one end side of which is continuous with the mold surface for molding the outer peripheral surface of the first mold, and the other end side is continuous with the mold surface forming the end surface. A mold for a rotor for a stepping motor, which is characterized in that 2. A substantially cylindrical rotor having a rotor shaft integrally formed at the center thereof, wherein an inclined surface is provided at a corner connecting an outer peripheral surface and an end surface of the rotor, and one end side of the inclined surface is the outer peripheral surface. A rotor for a stepping motor, characterized by being continuously connected to the rotor.