JPH05166656A - Manufacture of resin-bonded magnet - Google Patents

Abstract

PURPOSE:To manufacture a resin-bonded magnet, by using an extrusion molding method, wherein a drop in its magnetic performance is suppressed. CONSTITUTION:A magnet composition which has been molded temporarily to be a block shape by being oriented in a magnetic field or without being oriented is further extrusion-molded: an anisotropic magnet or an isotropic magnet is formed. Consequently, a resin-bonded magnet which has suppressed a drop in its magnetic performance can be manufactured by using an extrusion molding method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a resin-bonded magnet.

[0002]

2. Description of the Related Art As a method of molding a resin-bonded magnet, the following molding methods can be mentioned.

Compression molding method Injection molding method Extrusion molding method In each of the above methods, the kneaded magnet composition is directly fed to a molding machine for molding. Among them, in the extrusion molding method, first, heating and pressurization are performed at a temperature not lower than the temperature at which the resin is softened in the kneading process, kneading is performed, and the obtained magnet composition is fed to an extruder to narrow the melt into a predetermined shape. While this is a method of molding at the tip of the mold. When manufacturing an anisotropic magnet, it is necessary to orient the magnet composition using a magnetic circuit during molding. Unlike the other molding methods such as the compression molding method and the injection molding method, this extrusion molding method is a continuous molding type production system and therefore has excellent productivity. Moreover, it is possible to manufacture a magnet having a thin shape, a long shape, and the like.

[0004]

However, the above manufacturing method has the following problems.

(1) When it is attempted to highly fill the magnet powder, in the kneading step, the dispersibility of the magnet composition is decreased, and the viscosity of the magnet composition is increased, so that the torque of the kneading machine is increased and the kneading becomes difficult. However, there is a limit to high filling.
Further, even if a highly filled one is made anisotropic, the movement of the magnet powder is restricted by the high filling, so that the orientation becomes difficult and the magnetic performance commensurate with the filling amount cannot be obtained.

(2) Due to the high temperature process during kneading, thermal deterioration of the magnet powder is unavoidable, and the performance of the molded magnet deteriorates.

Therefore, the present invention solves such a problem, and an object of the present invention is to provide a resin-bonded magnet in which deterioration of magnetic performance is suppressed by using an extrusion molding method.

[0008]

The method for producing a resin-bonded magnet according to the present invention is a method for producing a resin-bonded magnet in which rare earth magnet powder is bound by an organic resin, and a mixture of the rare earth magnet powder and the organic resin is temporarily molded. After that, a ram extruder is further used for forming to obtain an isotropic magnet. Further, in a method for producing a resin-bonded magnet in which rare earth magnet powder is bound with an organic resin, a mixture or kneaded material of the rare earth magnet powder and an organic resin is oriented in a magnetic field and temporarily molded, and then a ram extruder is used. It is characterized in that it is oriented again in a magnetic field and molded to form an anisotropic magnet.

[0009]

According to the above-mentioned manufacturing method of the present invention, since the magnet composition is preliminarily molded into a block shape and is further molded using a ram extruder, it is possible to manufacture an extruded magnet with suppressed deterioration of magnetic performance. You can

That is, by using a method of molding a mixture of a rare earth magnet powder and an organic resin by a compression molding method or the like as temporary molding, it is not necessary to apply stress to knead and there is a restriction due to an increase in viscosity due to high filling of magnet powder. Since it is not affected, it becomes possible to make the magnet composition uniform and to manufacture a highly filled magnet composition as compared with the conventional method. A highly filled resin-bonded magnet can be manufactured by molding a ram extruder using this magnet composition.

An anisotropic block-shaped magnet composition can be obtained by using a method of orienting a mixture or kneaded material of a rare earth magnet powder and an organic resin in a magnetic field for temporary molding, and using this. When an anisotropic magnet is manufactured, it can be seen by the conventional molding method by extruding an anisotropic magnet with the orientation kept in advance using a ram extruder and then reorienting by a magnetic circuit during molding. It is possible to perform molding without causing insufficient orientation due to the decrease in the ease of movement of the magnet powder due to high filling. This makes it possible to manufacture an anisotropic magnet having a high degree of orientation even with a highly filled magnet.

Further, by using a molding method in which a mixture of a rare earth magnet powder and an organic resin is used in a low temperature process as compared with the conventional manufacturing method for temporary molding, the magnet composition is hardly affected by the heat and the magnetic composition. It becomes possible to manufacture things. By molding with a ram extruder using this magnet composition, it becomes possible to manufacture a resin-bonded magnet in which deterioration of magnet powder is suppressed.

[0013]

Examples As the magnet powder used in the present invention, a magnet powder having a basic composition of a rare earth metal and a transition metal mainly containing cobalt, or a magnet having a basic composition of a transition metal mainly containing a rare earth metal and iron and boron There is powder. Examples of the organic resin include thermoplastic resins such as polypropylene, polyphenylene sulfide and polyamide, and thermosetting resins such as phenol, epoxy and polyimide. A mixture or kneaded product of these magnet powder and organic resin is temporarily molded into a block shape by an arbitrary method. When manufacturing an anisotropic magnet, this temporary molding is performed in a magnetic field,
The easy axis of magnetization of the magnet powder in the magnet composition is oriented in the direction of the magnetic field. Next, the block-shaped magnet composition is fed to a ram extruder, and in a semi-molten state, ram-type extrusion is performed to form a straw-shaped isotropic magnet or anisotropic magnet. When manufacturing an anisotropic magnet, the semi-molten magnet composition is reoriented by a magnetic circuit during molding using a ram extruder. Here, the semi-molten state means a state in which the magnet composition temporarily molded is extruded by the plug flow.

A more detailed embodiment will be described below.

Example 1 A magnet powder having a composition of Nd ₁₄ (Fe _0.95 Co _0.05 ) _80.5 B _5.5 and a polyamide resin of the resins shown in Table 1 were mixed in the proportions shown in Table 2. And weigh both to mix.

[0016]

[Table 1]

[0017]

[Table 2]

This mixture is filled in a mold and adjusted to a temperature at which the organic resin is melted, and a block-shaped magnet composition is temporarily molded by a warm compression molding method. The molding conditions are as shown in Table 1. The molding pressure is 1.5 t / cm ² . Next, this block-shaped magnet composition is fed to a ram extruder and the mold temperature is set to the extrusion molding temperature shown in Table 1 to extrude a semi-molten block to form a straw-shaped isotropic magnet. .. The extrusion pressure was 50 kg / cm ² , the extrusion speed was 1 mm / sec, and the formed magnet was a straw-shaped magnet with a central angle of 115 °, a wall thickness of 1.2 mm, and an outer diameter of 5 mm.

As a comparative example, a mixture obtained by kneading the mixture under the conditions shown in Table 3 was similarly extrusion-molded to form a straw-shaped isotropic magnet.

[0020]

[Table 3]

Table 4 shows the filling ability of the magnet powder in the magnet composition.

[0022]

[Table 4]

Table 5 shows the magnetic properties of some magnets produced by changing the ratio of the magnet powder in the magnet composition.

[0024]

[Table 5]

As is clear from Tables 4 and 5, according to the process used in the present invention, it is not necessary to apply stress to knead, and there is no restriction due to an increase in viscosity due to high filling of magnet powder. It became possible to increase the filling amount, and it became possible to perform extrusion molding with high filling. The comparative example is based on a conventional process, and it is not possible to form a highly filled magnet composition because there is a limit to the high filling of the magnet powder in the kneading process.

As described above, by using the manufacturing method of the present invention, it is possible to manufacture a highly-filled magnet composition which could not be realized conventionally, and by using this, an isotropic extruded magnet having high magnetic performance is manufactured. can do.

(Example 2) Magnet powder having a composition of Nd ₁₄ (Fe _0.95 Co _0.05 ) _80.5 B _5.5 and one of the resins shown in Table 1 was used as 67 vol% of magnet powder and 33 vol% of resin. And weigh both to mix. This mixture is filled in a mold and temporarily molded into a block-shaped magnet composition by a cold compression molding method. The molding pressure is 1.5 t / cm ² . Next, this block-shaped magnet composition is fed to an extrusion molding machine, and the mold temperature is set to the molding temperature shown in Table 1 to extrude a semi-molten block by ram extrusion molding to produce a straw-shaped isotropic magnet. To mold. The extrusion pressure was 50 kg / cm ² , the extrusion speed was 1 mm / sec, and the formed magnet was a straw-shaped magnet with a central angle of 115 °, a wall thickness of 1.2 mm, and an outer diameter of 5 mm.

As a comparative example, a mixture obtained by kneading the mixture under the conditions shown in Table 3 was similarly extrusion-molded to form a straw-shaped isotropic magnet.

Table 6 shows the magnetic characteristics of this isotropic magnet.

[0030]

[Table 6]

As is clear from Table 6, according to the process used in the present invention, by suppressing the thermal deterioration at the time of molding the magnet composition, as shown in the coercive force, only the magnet powder shown in Comparative Example 3 was used. A value close to the original performance was obtained, and the magnet could be molded while suppressing the deterioration of the magnet powder.

Comparative Example 1 and Comparative Example 2 are based on a conventional process and are extruded using a kneaded pellet-shaped magnet composition. Since this magnet composition requires heating and pressurization during kneading and the overall process temperature becomes high, deterioration of magnetic performance due to heat deterioration of the magnet powder is observed.

As described above, by using the manufacturing method of the present invention, it is possible to manufacture an isotropic extruded magnet whose deterioration of magnetic performance is suppressed.

Example 3 A magnetic powder having a composition of Sm (Co _0.672 Cu _0.080 Fe _0.22 Zr _0.028 ) _8.35 and a polyamide resin among the resins shown in Table 1 are shown in Table 2. Magnetic powder that can be kneaded with
It is weighed so that each ratio is up to 72 vol%, and kneaded under the conditions shown in Table 3 to produce a pellet-shaped magnet composition. This is subjected to an injection molding method at a molding temperature of 270 ° C. to temporarily form an anisotropic magnet composition in the state where an orientation magnetic field of 15 kOe is applied. Next, this block-shaped magnet composition was fed to a ram extruder, and the mold temperature was set as shown in Table 1.
Extrusion with the anisotropy of the semi-molten block at the forming temperature shown in Fig.
An anisotropic magnet having a high orientation was manufactured by re-orienting by applying the orientation magnetic field. The extrusion pressure is 50 kg / cm ² , the extrusion speed is 1 mm / sec, the molded magnet has a central angle of 115 ° and a wall thickness of 1.
It was a straw-shaped magnet with an outer diameter of 2 mm and an outer diameter of 5 mm.

As a comparative example, a kneaded pellet-shaped magnet composition was directly fed to an extrusion molding machine and similarly oriented by an orientation magnetic field of 15 kOe to produce an anisotropic magnet.

FIG. 1 shows the magnetic characteristics of several magnets produced by changing the ratio of magnet powder in the magnet composition.

As is apparent from FIG. 1, according to the process used in the present invention, even when the filling amount of the magnet powder is increased, the anisotropically preformed anisotropic one is extruded while maintaining the orientation and further reoriented during the molding. Therefore, it is possible to manufacture an anisotropic magnet without causing performance deterioration in the high filling region. The comparative example is based on the conventional process, and the performance is deteriorated due to the difficulty of orientation in the high filling region.

As described above, by using the manufacturing method of the present invention, it is possible to manufacture an anisotropic extruded magnet in which the deterioration of the magnetic performance in the high filling region is suppressed.

Example 4 One of the magnetic powders having a composition of Nd ₁₄ (Fe _0.95 Co _0.05 ) _80.5 B _5.5 and one of the resins shown in Table 1 was used as 67 vol% of magnetic powder and 33 vol% of resin. And weigh both to mix. This magnet powder is obtained by hot pressing a thin strip obtained by the quenching method and further making it anisotropic by the die upset method. Fill the mold with this mixture,
Temporarily form into a block-shaped magnet composition anisotropy by a cold compression forming method while applying an orienting magnetic field of 15 kOe.
The molding pressure is 1.5 t / cm ² . Next, this block-shaped magnet composition was fed to an extrusion molding machine, and the mold temperature was used as the secondary molding temperature shown in Table 2, and a magnetic circuit was used when a semi-molten block was extruded by ram extrusion molding. An orienting magnetic field of 15 kOe is applied to reorient to form a straw-shaped anisotropic magnet. Extrusion pressure is 50 kg / cm ² , extrusion speed is 1 mm / sec,
The molded magnet has a central angle of 115 °, a wall thickness of 1.2 mm, and an outer diameter of 5 mm.
It was a straw shaped magnet.

As a comparative example, a mixture obtained by kneading the mixture under the conditions shown in Table 3 was similarly extrusion-molded to form a straw-shaped anisotropic magnet.

Table 7 shows the magnetic characteristics of this anisotropic magnet.

[0042]

[Table 7]

As is clear from Table 7, according to the process used in the present invention, by suppressing the thermal deterioration at the time of molding the magnet composition, as shown in the coercive force, only the magnet powder shown in Comparative Example 3 was obtained. A value close to the original performance was obtained, and the magnet could be molded while suppressing the deterioration of the magnet powder.

Comparative Examples 1 and 2 are based on a conventional process, and are extruded using a kneaded pellet-shaped magnet composition. Since this magnet composition has a high process temperature at the time of kneading, the magnetic performance is deteriorated due to the heat deterioration of the magnet powder generated at the time of kneading.

As described above, by using the manufacturing method of the present invention, it is possible to manufacture an anisotropic extruded magnet with suppressed deterioration of magnetic performance.

[0046]

As described above, by using the manufacturing method of the present invention, it is possible to manufacture an isotropic extruded magnet with suppressed deterioration of magnetic performance. Alternatively, an anisotropic extruded magnet having a high degree of orientation can be manufactured. These can be widely used for stepping motors, DC motors, sensors, etc., which are required to be small and precise and have high performance.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the filling ratio of magnet powder and magnetic performance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaaki Sakata Inventor Masaaki Sakata 3-3-5 Yamato, Suwa, Nagano Seiko Epson Co., Ltd. (72) Inventor Koji Akioka 3-3-5 Yamato, Suwa, Nagano Prefecture Seiko Epson Incorporated (72) Inventor Toshio Ikeda 1-20-8 Higashionuma, Sagamihara-shi, Kanagawa (72) Inventor Naoshi Nanjo 1-9-24 Higashibayashi, Sagamihara-shi, Kanagawa (72) Toshihiro Ichijo Sagamiono, Sagamihara-shi, Kanagawa 5-25-19 Yuri Heights 101 (72) Inventor Hirotaka Ikejiri 4-13-30 Onodai, Sagamihara City, Kanagawa Prefecture

Claims (2)

[Claims] 1. In a method for producing a resin-bonded magnet in which rare earth magnet powder is bound with an organic resin, a mixture of the rare earth magnet powder and an organic resin is preliminarily molded and then isotropically molded by using a ram extruder. A method for manufacturing a resin-bonded magnet, which is characterized in that the magnet is a magnetic magnet. 2. In a method for producing a resin-bonded magnet in which rare earth magnet powder is bound with an organic resin, a mixture or kneaded material of the rare earth magnet powder and an organic resin is oriented in a magnetic field for temporary molding, and then a ram extruder. A method for producing a resin-bonded magnet, which comprises reorienting in a magnetic field to form an anisotropic magnet.