JPS6288312A - Forming method for rare earth cobalt magnet in magnetic field - Google Patents

Abstract

PURPOSE:To make the orientation of powder in a low intensity magnetic field easy, by using magnetic powder which is demagnetized by an inverse magnetic field and pulverized after the previous magnetization in a ferromagnetic field and pressing, as the magnetic powder of rare earth cobalt to be filled in a die. CONSTITUTION:This equipments relates to the manufacture of a rare earth cobalt magnet having radial direction multipole. Prior to a press-molding in a magnetic field, the powder to be used is magnetized in a high intensity magnetic field, and then a press body is prepared. After demagnetization in an inverse magnetic field, the pressed body is pulverized into 20-mesh size to be used as the powder which is easy to be oriented in a low intensity magnetic field. the degree of orientation of each pole (N, S) is increased thereby, and the surface magnetic flux density B0[G] of a magnet periphery is intensified. Moreover, the rare earth cobalt magnet having radial direction multipole in which irregularities between each of poles are small can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for molding a multipolar magnet having a plurality of magnetic poles on the outer circumferential surface in a magnetic field in a 9-cylindrical rare earth conault magnet. , RCo5 series or R2CO1
This relates to a method for orienting powder when a 7-series rare earth co-gurt magnet has a small outer diameter and a sufficient orienting magnetic field cannot be obtained during pressing.

[Problems to be solved by the prior art and the invention] A cylindrical radial multipolar magnet made of rare earth cobalt magnets as shown in FIG. 2 has high efficiency and can be miniaturized. Therefore, users require that the outer diameter of the magnet be 12 mm or less.

Conventionally, this type of magnet is small in size, so a rare earth cobalt magnet magnetic field brace device shown in FIG. 1 is used. In this device, rare earth co-Gult magnet powder 3 is filled inside a mold consisting of a die 1 and a core 2, and an orienting magnetic field is applied by a coil 4 to generate a magnetic field from the tip of a pole piece 5. After being oriented, pressure is applied from the axial direction of the die using upper and lower nozzles as shown in the figure to produce a multi-pole oriented pressed body, which is processed to the final dimensions after firing and becomes a magnetized product. . The magnet obtained in this way is

The smaller the outer diameter of the pole, the smaller the magnetic field generated from the pole piece, making it difficult to obtain sufficient orientation and resulting in poor characteristics.
The variation between poles also increases.

Also, as a method that allows easy orientation with a weak magnetic field.

As shown in Figure 3, after filling the powder into the mold, the electromagnet 6
A manufacturing apparatus is known in which powder is magnetized using a strong magnetic field and then oriented using a multipolar electromagnet 7.

In this case, upper A'nch8. Since the lower gun 9 needs to be non-magnetic, the 9 magnetizing coil 6 is increased in size.

Equipment costs are also high.

Therefore, the present invention provides a method for easily orienting powder in a 9-weak magnetic field when manufacturing a radially multipolar magnet using a rare earth cobalt magnet.

[Failure to solve the problem]

According to the present invention, when performing press molding in a magnetic field in an apparatus for manufacturing rare earth cobalt magnets having multiple radial poles, the powder to be used is magnetized in advance in a strong magnetic field, and then the pressed body is formed. , after demagnetizing the pressed body in a reverse magnetic field -
A method for producing a rare earth cobalt magnet is obtained, which uses a magnet crushed into 20 meshes and can be easily oriented in a weak magnetic field.

According to the above manufacturing method, the degree of orientation of the multi-poles (N, S) is increased, the surface magnetic flux density BoCG of the outer circumferential surface of the magnet is improved, and at the same time, a rare earth cobalt magnet with uneven poles between each pole can be obtained.

〔Example〕

The present invention will be explained below with reference to Examples. In this example, the product shape is φ8×φ3.5×1. As O, the second
A manufacturing device for six radial poles as shown in the figure was used.

The powder used was SmCo5, which was magnetized using a vertical magnetic field press that generates a magnetic field of 20 kOe, press-molded, and then crushed. This powder is put into the above-mentioned device, and the multi-pole electromagnet is energized to orient the powder radially in the radial direction, and then press-molded by applying pressure from the axial direction.Then, the pressed body is fired to form a radial six-pole magnet. is obtained. The surface B of this magnet
The o[G] value and the variation between poles are as shown in Table 19.
An improvement of 250 [G] in surface BO value and a factor of 6 improvement in dispersion between electrodes was obtained.

Table 1 By using powder that has been made to have an anisotropic direction in this way, the properties were significantly improved compared to the conventional method.

〔Effect of the invention〕

As explained above, according to the present invention, powder can be easily oriented in a weak magnetic field. By incorporating the small radial multipolar rare earth cobalt magnet manufactured by this manufacturing method into an ultra-small motor or actuator, it consumes less power and can be made more efficient, making a significant contribution to industry.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining a radial multipolar magnet manufacturing device for rare earth cobalt magnets, Fig. 2 is a diagram for explaining a radial multipolar magnet, and Fig. 3 is a diagram for explaining an example of a conventional method. be. Explanation of symbols = 1 is die, 2 is core, 3 is powder. 4 is the coil, and 5 is the pole piece.

Claims (1)

[Claims] 1. Multipolar electromagnets are arranged along the outer circumferential surface of the cylindrical mold die so that N and S poles alternate, the inside of the die is filled with rare earth magnet powder, and the multipolar electromagnet is energized. After the powder is radially oriented in the radial direction, the powder inside the die is press-molded from the axial direction of the die, and the rare earth cobalt magnet powder is pre-deposited in a strong magnetic field to be filled inside the die. A method for molding rare earth cobalt magnets in a magnetic field, which uses magnet powder that has been demagnetized and crushed in a reverse magnetic field after magnetic press molding, thereby facilitating the orientation of the powder in a weak magnetic field.