JPS5870506A - Magnetization of rubber permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a rubber permanent magnet having strong attracting force without losing processability with the aid of inexpensive magnetic powder by a method wherein the second magnetization is done at the vicinity of the end section in the longitudinal direction of an attracting plane in the nearly same direction as that of the first magnetization after performing the first magnetization. CONSTITUTION:A rubber permanent magnet formed in rectangle is firstly maggetized by a magnetizing device having parallel magnetic poles. As to magnetization, a static magnetic field or a pulse-like magnetic field such as capacitor discharge may be acceptable by the kind of a DC power source. Next, the second magnetization is applied to the rubber permanent magnet completed the first magnetization by a magnetizing device providing an attracting surface with magnetic poles. The same condition and others as those for the first magnetization are applied. In this way, a rubber permanent magnet having strong attracting force can be manufactured with the aid of inexpensive magnetic powder and without losing processability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of magnetizing a rubber magnet, particularly a rubber magnet for attraction such as a rubber magnet for latch of a refrigerator door.

Rubber magnets are usually made of a material made by dispersing and mixing a magnetic material such as 7-elite powder with a flexible binder such as polyvinyl chloride, chlorinated polyethylene, or butyl rubber (including materials that are not formal IIc/II rubber, but for convenience, they are called rubber). It is manufactured by molding into a desired shape using a molding process such as extrusion, injection, compression, or rolling, and then magnetizing it.

Conventional 1. To obtain a rubber magnet with strong attraction, the following steps were taken: h) increasing the amount of magnetic material such as ferrite, (b) performing anisotropic treatment, and (c) using ferromagnetic magnetic powder. It is dangerous that methods such as these are being used. However, each of these means has the following drawbacks. That is, f4) As the amount of magnetic powder blended increases, the processability and physical properties of the finished rubber magnet decrease. If the magnetic powder in the magnet exceeds 92.5% by weight (approximately 70% by volume), dispersion mixing and moldability will be significantly impaired, making it impossible to obtain a homogeneous rubber magnet material. -) The anisotropic process becomes complicated and reduces the efficiency of one operation. (c) Ferromagnetic powders such as anisotropic fluorite samarium cobalt are expensive.

The present invention has been made in view of the shortcomings of the prior art, and is an improvement to the magnetization method for pigeon houses using rubber magnet material i containing inexpensive magnetic powder within a range that does not impair processability. By.

The present invention aims to provide a magnetization method that allows a rubber magnet with strong attraction force to be obtained.

In the present invention, first, the first magnetization is performed in a direction parallel to the attracting surface and perpendicular to the longitudinal direction, and after that, a magnetic pole is formed near the longitudinal end of the attracting surface in approximately the same direction as the tenth magnetization. The attraction force is increased by performing the 20th magnetization.

Hereinafter, using drawings, specific Ki1! I will clarify.

Mainly made of chlorinated polyethylene with a small amount of plasticizer (mp
etc.) Ferrite, which is a magnetic powder, is mixed and dispersed in a binder containing S stabilizer, lubricant, etc. using a kneader, mixer, roll, etc., and the adsorption surface has a rectangular cross section with a width of 8cm and a height of 4sII. When magnetizing a rubber magnet material by extrusion molding into a string shape, the physical properties, adsorption force, etc. of the processable rubber magnet material change depending on the type of ferrite, the amount mixed, and the direction of magnetization. Table 1 shows examples in comparison with conventional examples.

The anisotropic strontium ferrite used in Conventional Example 5 is approximately five times more expensive than the isotropic barium ferrite. If the proportion of magnetic powder in the rubber magnet material exceeds 92.5% by weight, the processability will be significantly impaired, and the rubber magnet material after extrusion will no longer be homogeneous, resulting in only a brittle product that is extremely brittle. The magnetization direction is shown in Figure 1 (α) and (b).
, (t')K When the bottom surface is used as the suction surface as shown,
Three types are possible: (α) t (b) t ('). The attraction force shown in Table 1 is obtained by cutting a magnetized rubber magnet with a cross section of 8II" x 4" into a length of 25cm.
Intermediate tlj using 0.5-thick non-magnetic metal as a spacer
This is the result of a study conducted by adhering a rubber magnet to soft iron and measuring its pulling force.

The magnetization method of the present invention will be explained in more detail as follows. First, a rectangular rubber magnet is magnetized using a magnetizing device having parallel magnetic poles as shown in FIG. 2(a)K.

In FIG. 2, 2 is a rubber magnet, 3 is a magnetic pole yoke core material, and 4 is a coil. Depending on the type of DC power supply (not shown), even if there is a static magnetic field, condensation may occur. It may also be a pulsed magnetic field such as that generated by electric discharge. The 10th magnetization according to FIG. 2 (4) differs depending on the type of magnetic powder, but when ferrite is used as the magnetic powder, it is necessary to apply a magnetic force of 8000 G or more, preferably more than Izooo (>). Next, the 1st δ magnetization The rubber magnet that has been subjected to the 20th magnetization is subjected to the 20th magnetization using a magnetization device having magnetic poles on the attracting surface as shown in FIG.

Table 1 did not show that the attraction force increased slightly even if the 10th magnetization was repeated more than 2 times, or the 20th magnetization was repeated more than 2 times. Effects like those of the present invention cannot be obtained.

As described above, by adopting the magnetization method according to the present invention as shown in the embodiments, a rubber magnet with strong attraction force can be manufactured using inexpensive magnetic powder without impairing workability.

[Brief explanation of drawings]

Figure 1 (g) l (h) 1 (0) is a perspective view showing the magnetization direction of the rubber magnet, and Figure 2 is a sectional view showing an embodiment of the magnetization method according to the present invention. (a) is the first magnetization. FIG. 2(b) shows the 20th magnetization. 1: Adsorption surface, 2: Rubber magnet. 3: Yoke core material, 4: Coil. Sai 1 figure (Kyu) (b) (C) 23

Claims (1)

[Claims] A method for magnetizing a long attracting rubber magnet having a roughly rectangular cross section, such as a rubber magnet for a latch on a refrigerator door.The tenth magnetization is performed parallel to the vIk surface and in a direction perpendicular to the longitudinal direction. A magnetizing force method for a rubber magnet, characterized in that, after that, a 20th magnetization is performed near the longitudinal end of the attracting surface so that the magnetic pole is in approximately the same direction as the first magnetization.