JPS6146006A - Anisotropic resin magnet - Google Patents

Abstract

PURPOSE:To increase a magnetizing quantity and to improve a precision of dimensions, by magnetizing a cut face which has been preliminarily cut in an any depth. CONSTITUTION:A cut face which has been preliminarily cut in an any depth is magnetized. It is preferable that the cut face may be approximately rectangular to the aligning orientation of magnetic powder in resin magnet and that the cut depth is 0.1-0.5mm. from the surface. The resin magnet generatlly has extreamly bad orientation alignment near the surface layer of the mold and therefore is almost isotropic due to a cooling rate difference between the surface section and the internal section during the molding. Accordingly, by cutting the surface with bad orientation alignment and magnetizing the cut face, the magnetizing quantity can be increased and the precision of the dimensions can be conderably improved.

Description

Detailed Description of the Invention: "Industrial Application Field" The present invention relates to an anisotropic resin magnet with a large amount of VA (surface magnetic flux density), and more specifically, the amount of magnetization obtained by magnetizing a pre-cut surface. This invention relates to an improved anisotropic resin magnet.

``Prior Art'' ``Problems to be Solved by the Invention'' Recently, plastic magnets have attracted attention in place of sintered ferrite magnets and are being produced in large quantities.

The biggest advantage of plastic magnets is that they can be mass-molded using ordinary plastic molding methods, and products with complex shapes can be obtained with high precision. On the other hand, the plastic magnet +1 has the disadvantage that the amount of adhesion expected from the (BH)IIIax value cannot be obtained and the dimensional accuracy tends to be poor.

The former is thought to be because the surface layer of the molded product cools faster than the inside, resulting in the magnetic powder solidifying during orientation, resulting in an insufficient degree of orientation, and the latter, shrinkage and shrinkage after molding. This is thought to be due to a taper change.

``Means for Solving the Problems'' The inventors of the present invention were aware of the actual situation, and as a result of intensive research to solve the problem of low magnetization on the surface of the plastic magnet, they found that by cutting the surface, the desired result could be achieved. The present invention has been completed based on the discovery that the above objects can be achieved.

The present invention includes an anisotropic resin magnet that is magnetized on a cut surface that has been cut to an appropriate depth in advance.

The present invention uses an X-ray diffractometer, (OO
8) Calculate the orientation of ferrite particles in the molded product by observing the relative ratio of the peak heights of reflection and (107) reflection, and as a result, the orientation near the surface layer of the molded product is extremely low; It was discovered that it is close to isotropic. Furthermore, in the course of the research, 0.1 mm or more from the surface, preferably 0.5 mm
It was found that a satisfactory amount of magnetization can be obtained by scraping off the surface with such a low degree of orientation and magnetizing the cut surface.

In the present invention, it is desirable that the cutting surface be approximately perpendicular to the orientation direction of the magnetic powder in the resin magnet, and that the cutting depth is preferably 0.1 to 0.5 mm from the surface. Cutting depth is above &! If it is shallower than the cutting depth, the amount of magnetization will not increase much, and if the cutting depth is large, the amount of magnetization will generally improve, but on the other hand, it will increase the cost, and depending on the magnet, even 11 IJs more than necessary will not be effective. , it is preferable to set the upper limit to about 0.5 mm and select it appropriately within that range. The ratio between the magnetization pitch Mp and the thickness (I) of the resin magnet is Mp/
When H < 1, the effect is significant. That is, when the ratio is 1 or more, the influence of the surface layer becomes small, so cutting often simply results in high cost.

The present invention will be explained below with reference to Examples and Comparative Examples.
The present invention is not limited in any way by these.

Example 1 The resin magnet composition shown in Table 1 was kneaded twice at 230° C. in a 32 mm full-flight mixer, cooled, and pulverized into pellets. Using the pellets, under the magnetic field orientation conditions shown in Table 2, (A) a plate-shaped molded product (oriented in the thickness direction) of 20 mm x width 40 mm x 4 mm thickness (orientated in the thickness direction) and CB) an outer diameter of 43 mm x inner diameter of 37 mm x height of 10 mm. A cylindrical molded product (oriented in the radial direction, that is, the thickness direction) was obtained, the cutting depth was varied as shown in Table 3, and the amount of magnetization (average surface magnetic field bias value) was measured. In addition, the magnetic properties of the molded product (A) (
BH) max was 2.0, (n) was 1.8, the pitch of the magnetizing yoke was 1.35 mm, and the number of poles was loo. To measure the amount of magnetization, use Gaussmake-rGM-12 manufactured by Denshi Magnetic Industry Co., Ltd.
A Hall probe of type 25J and rT-IJ was used.

The results are shown in Table 3.

Table 1 Strontium ferrite powder (average particle t1.1μm
)90wt% polyamide 12
IQKBM603 (Shin-Etsu Chemical m) 0.5 Irganox 1098 (manufactured by Ciba Geigy) 0.5
Table 2 Mold temperature 80”C injection ~
300'C injection pressure
1.5L/co! cooling time
20 seconds Magnetic field application time 10 seconds Magnetic field inside the cavity 6000 0e (both left and right)
Table 3 From the results in Table 3, when the cutting depth is Q and 1 mm, it is approximately 5%.
It is recognized that the amount of magnetization improves by about 10% at 0.5 mm. In addition, the dimensional accuracy is ±0.3 for the uncut one.
mm, whereas the cut material of the present invention is ±0.0
It was 5 mm, which was extremely good.

"Function""Effects of the Invention" As mentioned above, the resin K1 stone of the present invention is obtained by cutting the insufficiently oriented portion of the surface layer due to the difference in cooling rate between the surface layer and the inside during molding. This has the advantage that the amount of magnetization is improved by about 5 to 10% and the dimensional accuracy is also greatly improved.

Claims (1)

[Claims] 1. An anisotropic resin magnet formed by magnetizing a cut surface that has been cut to an appropriate depth in advance. 2. The magnet according to claim 1, wherein the cut surface is generally perpendicular to the orientation direction of the magnetic powder in the resin magnet. 3. The magnet according to claim 1 or 2, wherein the cutting depth is 0.1 to 0.5 mm. 4. The magnet according to claim 1, wherein the ratio of the magnetization pitch (Mp) to the thickness (H) of the resin magnet is Mp/H<1.