JPS6139725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a magnetically anisotropic rotor magnet having an easy axis of magnetization in the radial direction.

It is well known that by radially orienting the axis of easy magnetization, the magnetic properties of a rotor magnet, and thus the performance of a motor incorporating such a rotor, can be greatly improved.

Therefore, various methods have been devised in the past to align the axes of easy magnetization in the radial direction. A typical example is the magnetic field forming method. In this method, for example, anisotropic barium ferrite powder is dispersed in a medium, a magnetic field is applied from the outside to align the axes of easy magnetization, and then pressure molding is performed. However, this method requires large-scale equipment, takes a long time to form, is not suitable for mass production, and is difficult to make small, multi-pole, and even thin ring-shaped products. There are drawbacks.

Therefore, in recent years, as an alternative to this method, the shape anisotropy of hexagonal ferrite has been utilized,
By press-rolling the kneaded material with an organic binder into a sheet, the axis of easy magnetization is oriented in the direction perpendicular to the sheet surface, and the resulting magnetic sheet is wound around a roller under pressure. A method has been developed for manufacturing magnets that can be integrated into layers to provide magnetic anisotropy in the radial direction.

However, in the case of such a so-called sheet lamination method, although the radial anisotropy is extremely excellent, steps are inevitably formed at the beginning and end of the sheet, and post-processing of these parts becomes cumbersome.
In other words, polishing is always required before or after firing, and there is a risk of delamination. It is also quite difficult to make a rotor ring with a very thin thickness.

The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a large-scale and expensive process without using special magnetic field treatment or end-of-roll treatment, which is indispensable in the sheet lamination method. No equipment required;
It is an object of the present invention to provide a method for easily and inexpensively manufacturing a high-performance radial anisotropic magnet rotor.

The present invention includes two inventions, but in either case, a plastic permanent magnet material sheet having an axis of easy magnetization in the thickness direction is drawn into a molded body having a ring-shaped part having anisotropy in the radial direction. It takes advantage of the common technical characteristics of

Hereinafter, embodiments of the present invention will be described in more detail based on the drawings. First, the material sheet used in the present invention will be explained. The magnetic sheet used as the raw material may be any sheet of plastic permanent magnet material that has an axis of easy magnetization in the thickness direction. For example, ferrite powder with a hexagonal magnetoprivite crystal structure made by combining oxides such as barium, strontium, or lead with ferric oxide is kneaded with a thermoplastic organic binder, and the kneaded product is mixed with a thermoplastic organic binder. Preferably, the material is pressure-rolled and the easy axis of magnetization is oriented perpendicular to the sheet surface by utilizing the shape anisotropy of the ferrite powder.

In the first invention, as shown in FIG.
A cup-shaped molded body 4 as shown in FIG. 2 is obtained by drawing. Since the present invention is primarily intended to manufacture rotor magnets with a low height, the drawing process is shallow, and the presser plate required in normal drawing process is not necessarily required. Further, when a sheet using a thermoplastic organic binder as described above is used as the anisotropic sheet 1, processability is further improved by heating the die 2 and punch 3. By drawing a sheet having an easy axis of magnetization in the thickness direction, the ring-shaped part 5 of the cup-shaped molded body 4 has an easy axis in the radial direction, and the flange part 6 and flat bottom part 7 have easy axes in the axial direction. become.

Next, such a cup-shaped molded body 4 is inserted into a punching die 10 having a housing part 8 of the ring-shaped part 5 and a die hole 9 that is approximately equal to the inner diameter of the ring-shaped part 5, and is inserted from the die hole 9 from above. The flat bottom part 7 of the cup-shaped molded body 4 is punched out with a punch 11 having a slightly small diameter. Additionally, the flange portion 6 is also removed. By doing so, a rotor magnet 12 having an axis of easy magnetization in the radial direction as shown in FIG. 4 can be obtained. In this embodiment, the cup-shaped molded body 4 is first drawn and formed, and then transferred to another mold and the flat bottom portion 7 is punched out. However, the drawing process is performed using a single mold. It is also possible to perform the punching process and the punching process continuously. Therefore, according to the present invention, without the need for large-scale manufacturing equipment,
It can be produced continuously in large quantities, and uniform seamless rings with no edges at the beginning or end of the winding can be manufactured. Furthermore, not only circular rings but also heterogeneous rings can be manufactured depending on the shape of the mold.

The rotor magnet 12 thus obtained is usually sintered before use. However, depending on the properties of the organic binder, it is also possible to use the molded product as it is as a non-sintered type. In any case, in order to assemble a rotor using such a rotor magnet 12, exactly the same method as the conventional method can be adopted. In other words, the rotor magnet 12 magnetized in the radial direction,
A shaft 13 and a rotor ring 14 made of aluminum or synthetic resin are prepared separately, and the three are integrated by press-fitting or gluing as shown in FIG. In this way, a rotor with radial magnetic anisotropy can be manufactured.

Next, the second invention will be explained. The steps up to obtaining the cuff-shaped molded body 4 are exactly the same as in the case of the first invention. Therefore, descriptions regarding them will be omitted. As shown in FIG. 6, the cup-shaped molded body 4 is housed in a punching die 20 that can accommodate the ring-shaped part 5 and the flat bottom part 7 and has a die hole 19 that is approximately equal to the shaft diameter. A through hole 22 is punched with a hole punch 21. Of course, depending on the mold structure, as in the case of the first invention, the drawing process of the cup-shaped molded body 4 and the drilling process of the through hole 22 for shaft insertion may be performed continuously in the same mold. It is also possible to do so.
Additionally, the excess flange portion 6 is also removed. In this way, a rotor magnet 23, which is a final molded body, as shown in FIG. 7 is obtained. In this case, as in the first invention, a sintered body may be used, or depending on the organic binder, it may be used as a non-sintered body. As shown in FIG. 8, insert the shaft 24 into the through hole 22,
Secure and integrate with adhesive, etc. The shaft 24 may be magnetized before being inserted, or may be magnetized after being inserted. In this case, in addition to magnetizing only the ring-shaped part 5 and using it only as a rotor, if the flat bottom part 7 is also magnetized and a magnetically sensitive element etc. is arranged opposite to the flat bottom part 7, a rotation sensor can be used. It can also be used as

Therefore, in addition to the advantages mentioned in the first invention, the present invention does not require a special rotor ring,
Integral machining has the advantage of improving center accuracy and making manufacturing even easier.

As described in detail above, the present invention obtains a ring-shaped or cup-shaped rotor magnet with an axis of easy magnetization oriented in the radial direction by drawing a sheet of plastic permanent magnet material having an axis of easy magnetization in the thickness direction. Because of this structure, there is no need for complicated and expensive processes such as special magnetic field treatment or sheet end treatment as in conventional methods.
Furthermore, high-performance, uniform, seamless radial magnetic anisotropic rotor magnets can be produced in large quantities easily and inexpensively without using large-scale equipment.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the drawing process according to the present invention,
Fig. 2 is a perspective view of the cup-shaped molded product obtained by the process, Fig. 3 is an explanatory diagram of the punching process of the flat bottom part, Fig. 4 is a perspective view showing an example of the final molded product, and Fig. 5 The figure is a sectional view of a rotor assembled using the same, FIG. 6 is an explanatory diagram showing the step of drilling a through hole, FIG. 7 is a perspective view showing another example of the final molded product, and FIG.
The figure is a sectional view of a rotor assembled using the same. 1...Plastic permanent magnet material sheet, 2...Dice, 3
... Punch, 4... Cup-shaped molded body, 5... Ring-shaped part, 7... Flat bottom part, 10... Punching die, 11...
Punch punch, 12...Rotor magnet, 20...Drilling die, 21...Drilling punch, 22...Through hole for shaft insertion, 23...Rotor magnet.

Claims (1)

[Scope of Claims] 1. A sheet of plastic permanent magnetic material having an axis of easy magnetization in the thickness direction obtained by molding a kneaded material of magnetic powder and an organic binder into a sheet shape is drawn into a cup-shaped molded body, A radial magnetic anisotropy characterized in that the ring-shaped part of the cup-shaped molded body has an axis of easy magnetization oriented in the radial direction, and then the flat bottom of the cup-shaped molded body is cut off to form it into a ring shape. A method for manufacturing a directional rotor magnet. 2. A sheet of plastic permanent magnetic material having an axis of easy magnetization in the thickness direction obtained by forming a kneaded material of magnetic powder and an organic binder into a sheet shape is drawn into a cup-shaped molded body, and the cup-shaped molded body is A radial magnetic anisotropic rotor magnet characterized in that the ring-shaped part has an axis of easy magnetization oriented in the radial direction, and a hole for shaft insertion is bored in the center of the flat bottom of the cup-shaped molded body. Production method.