JPH03203558A - Magnetizing method for stepping motor - Google Patents

Abstract

PURPOSE:To improve work efficiency by integrally press-molding all bar-shaped permanent magnets installed between rotor teeth and a magnet body consisting of a disc part for uniting these bar-shaped permanent magnets, and then magnetizing said magnet body by passing a magnetic flux through press molds. CONSTITUTION:For all bar-shaped permanent magnets 22 to be put between the rotor teeth of a rotor iron core 16, one end each of them is connected with one another by a disc part 22A so as to make a magnet body 22B. For the magnet body 22B, rare earth magnetic material is used, and is molded by a molding instrument 100, and is hardened by sintering. That is, clay-form material is put between a pair of inner and outer press molds 102 and 104, and is pressed to form the magnet body 22B. Coils 106 and 108 are wound on each press mold 102 and 104 and before the material after press molding hardens, the coils 106 and 108 are electrified so as to magnetize the bar-shaped permanent magnets 22 and the disc part 22A of the rotor iron core 16, and in the assembled conditions those are magnetized further.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a hybrid stepping motor in which a rod-shaped permanent magnet is fixed between the rotor teeth and between the stator teeth to increase torque. This relates to a method of magnetizing a magnet body.

(Prior art) There is a demand for the development of a small and lightweight motor, that is, a motor with high output density (motor torque/motor weight), as an actuator for the drive mechanism of precision control equipment for OA, FA, etc. .

Conventionally, hybrid stepping motors have been widely used as such actuators. This motor consists of a disk-shaped permanent magnet that is magnetized in the axial direction, sandwiched between a pair of rotor cores, and each rotor core has a 1/2 pitch. This type of motor has rotor teeth that are out of phase to periodically excite the stator magnetic poles.In this type of motor, a large number of Because it has teeth (inductors), the air gap magnetic flux density changes as the magnetic resistance changes depending on the rotor position.This changes the magnetic energy and produces torque.In this case, the motor can be driven to high output. In order to increase the density, it is possible to narrow the air gap length or increase the magnetic loading and electrical loading.However, if this is done, the core teeth may become magnetically saturated or the magnetic flux may leak to the tooth side. A problem arises in that it becomes difficult to increase the torque and the motor becomes larger.

Therefore, the applicant proposed fixing rod-shaped permanent magnets in the grooves between the rotor teeth and the stator teeth. This is to cancel the main magnetic flux generated on the surface of the rotor core by a disk-shaped permanent magnet using a rod-shaped permanent magnet magnetized in the radial direction, and forcibly suppress the leakage of 6B flux to the tooth groove bottom and tooth side. be.

4 to 7 show this already proposed motor. That is, Fig. 4 is a radial cross-sectional view, Fig. 5 is an axial cross-sectional view, Figs. 6A and 6B are developed views of the magnetic poles taken along the lines A-A and B-B in Fig. 5, and Fig. 7 is a cross-sectional view of the magnetic poles. It is a perspective view of a rotor.

In these figures, the reference numeral 10 is a rotor, which includes a loaf shaft 12, a disk-shaped permanent magnet 14, and a pair of rotor cores 16 (1
6a, 16b), and rod-shaped permanent magnets 22 (22a, 22b) fixed between the rotor teeth 18 (18a, 18b) formed on the outer peripheral surface of both rotor cores 16. The disk-shaped permanent magnet 14 is magnetized in the axial direction as shown in FIG.
8b, the phase is shifted by 1/2 pitch, as can be seen by comparing FIG. 6A and FIG. 6B. The rod-shaped permanent magnet 22 is magnetized in the radial direction, and its polarity is in a direction that cancels out the main magnetic flux produced by the disk-shaped permanent magnet 14.

24 is a stator, and each rotor core 16a, 16 is provided on the inner peripheral surface of the stator pole 26, which is protruded at equal intervals in the circumferential direction.
axial stator teeth 28 (28a, 28
b) is formed, and rod-shaped permanent magnets 32 (32a, 32b) are fixed in the grooves between the stake teeth 28. Here, the rod-shaped permanent magnets 32 are magnetized with the same polarity in the radial direction as the rod-shaped permanent magnets 22a, 22b of the respective rotor cores 16a, 16b. 34 is an @ wire wound around each stator pole 26.

In the previously proposed motor having such a configuration, the rod-shaped permanent magnets 22 are inserted one by one into the loaf grooves 20a and fixed with adhesive, as shown in FIG. The rod-shaped permanent magnets 32 on the stator 24 side were also adhesively fixed one by one in exactly the same way.

However, the width and thickness of the rod-shaped permanent magnet 22 of the rotor are 0.5~
Since it is quite small at about 2 mm and is easily damaged by impact, there has been a problem that the yield of fixing it is poor. In particular, when attaching a pre-magnetized bar-shaped permanent magnet 22 to the rotor 10, since the polarity of the bar-shaped permanent magnet 22 is opposite to that of the disk-shaped permanent magnet 14, it receives a repulsive force when inserted, resulting in poor workability. This makes the magnet 22 more likely to be damaged.

Therefore, it has been considered to combine the rod-shaped permanent magnet 22 on the rotor side with a disk portion to form an integrated magnet body, and to fix this to the rotor core. When making this magnet body from a rare earth magnetic material with high coercive force, this material is molded into a predetermined shape while it has clay-like fluidity, and then placed in a magnetic field before hardening to develop magnetic anisotropy. It is necessary to give.

(Object of the Invention) The present invention has been made in view of the above circumstances, and is intended to improve workability when attaching a bar-shaped permanent magnet between rotor teeth, and to make the bar-shaped permanent magnet less likely to be damaged. Therefore, when a bar-shaped permanent magnet is integrated with a disk part to form a magnet body, this magnet body is applied to rare earth magnetic materials that need to be imparted with magnetic anisotropy while still having fluidity. The purpose of this invention is to provide a method for magnetizing a stepping motor.

(Structure of the Invention) According to the present invention, this object is achieved by forming rotor teeth that are shifted in phase by 1/2 pitch from each other on each of a pair of rotor cores that sandwich a disc-shaped permanent magnet that is magnetized in the axial direction; In a hybrid stepping motor in which radially magnetized rod-shaped permanent magnets are fixed in the grooves between the rotor teeth and the stator teeth, all the rod-shaped permanent magnets installed between the rotor teeth,
A magnet body formed by integrally molding the disk part to which one end of the rod-shaped permanent magnet is connected is press-molded with a rare earth magnetic material having fluidity using an inner and outer press mold, and the inner and outer
This is achieved by a method of magnetizing a stepping motor, which is characterized in that the magnet body is magnetized in its thickness direction while it has fluidity by passing a magnetic flux through an outer press die.

(Example) Fig. 1 is a perspective view showing a rotor core and magnet body according to the present invention, Figs. 2A and 2B are axial cross-sectional views showing two embodiments of the assembled state of the rotor, FIG. 3 is a diagram showing a magnetizing device for a magnet body.

The rod-shaped permanent magnets 22 that fit between all the rotor teeth 22 of one rotor core 16 are connected at one end by a disk portion 22A, and these rod-shaped permanent magnets 22 and the disk portion 22A form a magnet body 22B. has been done.

This magnet body 22B is made using a molding machine 100 shown in FIG. 3, for example. In this case, the magnet body 22B is made of rare earth magnetic material. Rare earth magnetic materials are made by molding a material with clay-like fluidity into a predetermined shape and then sintering it. It is necessary to impart a predetermined magnetic anisotropy by applying this process. In this embodiment, the clay-like material is placed between a pair of inner and outer press molds 102 and 104 and pressed to form a magnet body 22B having the shape shown in FIG.

Here, each press mold 102, 104 has a coil 106.1.
08 is wound, a current is passed through these coils 106 and 108 in a state before the material after press molding hardens, and the third
A magnetic flux is formed as shown by the broken line in the figure. As a result, magnetic anisotropy is imparted to the rod-shaped permanent magnet portion 22 of the magnet body 22B in the radial direction, and to the disk portion 22A in the axial direction. Note that when aligning the open end of each rod-shaped permanent magnet 22 from one end of the rotor teeth 18 to the groove between the rotor teeth 18 and pushing it into the groove, an adhesive is applied in the groove. Similarly, magnet body 1
22B is molded.

The magnet bodies 22B, 122B formed in this way are
As shown in the figure, it is fitted into the rotor core 16 and magnetized in this assembled state. That is, the magnets 22B, 122B are attached by being sandwiched between the magnetic poles surrounding the outer periphery and the outer surface of the disk portion of the magnets 22B, 122B and the magnetic pole contacting the end surface of the rotor core 16, and passing magnetic flux between the two magnetic poles. be magnetized.

After being magnetized in this way, these are shown in Figure 2A or 2B.
It is assembled as shown in the figure. The one in Figure 2A is the magnet body 2
2B from the opposite side of the disk-shaped permanent magnet 14 to the rotor core 16.
It was installed on. In the case shown in FIG. 2B, two preliminary assemblies are prepared in which the magnet body 22B is attached to the rotor core 16, and these are assembled so that the disc-shaped permanent magnet 14 is sandwiched between the disc portion 22A of the magnet body 22B. It is.

The magnet body 22A is made of a rare earth magnetic material in the above embodiment, but it may also be made of a magnet made of an elastic material such as a rubber magnet or a plastic magnet in which metallic magnetic material is dispersed. can be firmly fixed between the rotor teeth 18 due to the elasticity of the bar-shaped permanent magnet 32 itself.

(Effects of the Invention) As described above, the present invention combines all the rod-shaped permanent magnets fixed between the rotor teeth with the periphery of the disc part using a rare earth magnetic material and integrates them to form a magnet body, In order to be able to fix this to the rotor core at once, this magnet body is formed using an inner and outer press mold, and during press molding, a magnetic field is applied using the press mold before the material hardens. Because it imparts magnetic anisotropy to the magnet body in the thickness direction,
The magnet body can be easily formed and magnetized.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a rotor core and a magnet body according to the present invention, FIGS. 2A and 2B are axial cross-sectional views showing two embodiments of the assembled state of the rotor, and FIG. 3 is a magnet body. FIG. 2 is a diagram showing a body magnetization device. 4 to 7 are diagrams showing the previously proposed motor. FIG. 4 is a radial sectional view thereof, FIG. 5 is an axial sectional view, and FIGS. B-
FIG. 7 is a developed view of the magnetic poles in the cross section taken along the line B, and is a perspective view of the rotor. 0... Rotor, 4... Disc-shaped permanent magnet, 6... Rotor core, 8... Rotor tooth, 2... Rod-shaped permanent magnet, 2A... Disc part, 2B... Magnet Body, OO...Magnetizing device, 02.104...Press mold, 06.108 Coil.

Claims (1)

[Claims] A pair of rotor cores sandwiching a disc-shaped permanent magnet magnetized in the axial direction are provided with rotor teeth that are 1/2 pitch out of phase with each other. In a hybrid stepping motor in which rod-shaped permanent magnets magnetized in the radial direction are fixed in grooves, all the rod-shaped permanent magnets installed between the rotor teeth are integrated with a disk portion to which one end of the rod-shaped permanent magnets is connected. A magnet body formed by molding is made of a rare earth magnetic material with fluidity inside.
1. A method of magnetizing a stepping motor, which comprises press-molding with an outer press mold, and magnetizing the magnet in the thickness direction while the magnet body has fluidity by passing a magnetic flux through the inner and outer press molds.