JPH04163905A - Rare earth resin bonded magnet - Google Patents

Abstract

PURPOSE:To obtain a high performance magnet with an excellent dimension precision and high shape freedom by adding an organic resin to a permanent magnet powder which has a basic composition consisting of rare earth metal and transition metal and conducting multistep compression formation. CONSTITUTION:An epoxy resin is added to a powder with an atomic breakdown of Nd14Fe70Co10B6 and formed by an ultraquenching method and after compression forming, a magnet is obtained through thermal hardening. When the compression formation is conducted in two steps, measurement variation is reduced, high densities are achieved, and the internal density difference is minimized. In particular, this difference becomes more noticeable as the mold thickness increases. Therefore, by using a multi-step formation process, it is possible to obtain a high performance magnet with excellent measurement precision and high shape freedom.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention involves filling a mold with a raw material obtained by adding an organic resin to magnet powder whose basic composition is a rare earth metal (R) and a transition metal, and after compression molding. By performing multi-step compression molding by removing a punch from one side and then filling it with raw materials, a larger molded size can be obtained with a high-density, high-performance magnet with excellent dimensional accuracy, resulting in a rare earth resin bond with a high degree of freedom in shape. Regarding type magnets.

[Conventional technology]

Rare earth resin bonded magnets can be roughly divided into samarium/cobalt based and neodymium/iron based, each of which is a high performance magnet.
As a magnet with a high degree of freedom in shape, it has contributed to the miniaturization and high performance of various applied products. Among them, neodymium,
Production of iron-based materials is rapidly increasing, taking advantage of the stability, low cost, and high performance of the raw materials.

A magnet with a desired shape was obtained by molding a magnet to which an organic resin was added using the powder as shown above.

[Problem to be solved by the invention]

In magnet molding, high density is used to improve the performance of the magnet, but the powder absorbs pressure, so the density on the inside of the magnet is not very high.Also, as shown in Figure 1, Since there is a large density difference between the ends and the center in the compression direction, dimensional differences occur due to differences in springback during molding.There is also a limit to the molding thickness that can be obtained by filling twice. If the height is too high (then the above-mentioned problem becomes noticeable), there is a problem that there is no degree of freedom in shape.

In addition, products with a molding thickness exceeding the limit molding thickness can be obtained by bonding two or more magnets together, but there is also the problem of high costs due to additional steps.

・In order to solve these conventional problems, the present invention achieves uniform high density, high performance, and even greater molding thickness by performing multi-step molding that repeats molding, filling, and molding. The purpose is to obtain a magnet with high dimensional accuracy that can be

[Means to solve the problem]

In order to solve the above problems, the rare earth tree of the present invention.

The basic composition of fat bonded magnets is rare earth metal (R).

A magnet made by adding an organic resin to a permanent magnet powder made of a transition metal and compression molding, and is characterized by multi-stage molding.

As shown in Figure 2, multi-stage molding improves dimensional accuracy by reducing the density difference (and reducing springback). However, by multistage molding, the thickness can be increased during molding, and a high molded thickness can be obtained without post-processing.

In addition, the permanent magnet powder whose basic composition is rare earth metal (R) and If transfer metal includes samarium, cobalt-based, neodymium, iron-based powder, and those in which these are replaced with other rare earth metals or M transfer metals. The present invention is not limited to a specific composition as similar effects can be obtained with other compositions [Example] (Example 1) The atomic ratio is Nd, Fθ,. COl. B6 powder obtained by an ultra-quenching method was mixed with an epoxy resin, and after compression molding, the mixture was heat-cured to obtain a magnet.

Table 1 shows the shapes and molding conditions, and the dimensions, internal density difference, and density of the one-stage and two-stage molded products were compared. Those with the same outer and inner diameters were molded under the same pressure.

The outer and inner diameter dimensions indicate the NAX value and MiN value of the compact, and the internal density difference indicates the density difference between the three divided products when the compact is divided into six equal parts in the axial direction, expressed as a percentage.

For any of the shapes in Table 1, two-stage molding results in smaller dimensional variations and higher density with the same pressure.
The internal density difference is small.

In particular, when the molding thickness becomes thicker (the difference becomes larger), high performance can be achieved by two-stage molding.

(Example 2) Table 2 shows the results of multi-stage molding by adding an epoxy resin to magnet powder having a composition of Sm1(Oo, ?e, Ou, Zr)Iy. Part 2 shows a one-stage molded product as a comparative example.
As shown in the table above, multi-stage molding makes it possible to increase the molding thickness without significantly reducing the density, and by performing five-stage molding, it is possible to mold an article twice as thick as one stage.

(Example 3) Comparison of dimensional accuracy was made when Samples 5, 4, and 7.8 shown in Example 1 were assembled into the rotor and yoke of a motor. The yoke dimensions were the same.

Figure 3*4tsts shows the shape of the sample bonded to the yoke.

Table 3 shows a comparison of samples 3 and 4, and Table 4 shows a comparison of samples 7.
A comparison of 8 is shown.

As shown in Table 4, two-stage molded products have high edge accuracy even when actually used.

In addition, multi-stage molding is also advantageous in terms of cost, since when two single-stage molded products with half the molding thickness are glued together, a step will inevitably occur after adhesion due to coaxiality or ridges, resulting in high processing costs.

〔Effect of the invention〕

As described above, the present invention has a basic composition of rare earth metal (R).
,l! ! Since permanent magnet powder made of a transferable metal is mixed with an organic resin and molded in multiple stages, it has the effect of obtaining a high-performance magnet with a high degree of freedom in shape and high dimensional accuracy.

The use of these magnets not only stabilizes the magnetic flux of stepping motors, DC motors, speakers, sensors, etc., but also has the effect of improving performance and reducing costs.

[Brief explanation of drawings]

Figure 1 shows the shape and internal density distribution of a cylindrical magnet when it is compressed in the direction of the arrow.
The fin is the lowest point). FIG. 2 is a diagram showing the shape and internal density distribution of a cylindrical magnet formed in two stages in the direction of the arrow. FIG. 5 is a diagram showing a state in which the magnet of Sample 3 of Example 1 is assembled in a rotor. FIG. 4 is a diagram showing a state in which the magnet of Sample 4 is assembled into a rotor. FIG. 5 is a diagram showing the state in which the ° magnet of Sample 7 is assembled into the rotor. FIG. 6 is a diagram showing a state in which the magnet of Sample 8 is assembled into a rotor. 1...Shaft 2...Rotor 6...Magnet 4...Yoke 5... ...Magnet and above Applicant Seiko Epson Corporation

Claims (1)

[Claims] (1) A rare earth resin-bonded magnet, which is a magnet made by adding an organic resin to permanent magnet powder whose basic composition is a rare earth metal (R) and a transition metal and compression molding the same, and which is characterized by being subjected to multi-step molding.