JPH04267309A - Focused orientation long magnet - Google Patents

Abstract

PURPOSE:To improve the surface magnetic fields of the magnet use face in a long magnet where the longitudinal length is longer than the diameter of the end face. CONSTITUTION:The working area of a high surface magnetic field is gotten by making working areas, where the directions of the orientation of magnetic particles focus, at the parts of the outlines in the cross sections which cross the longitudinal directions of long magnets, and placing those working areas in a row in the above longitudinal direction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elongated magnet whose length in the longitudinal direction is longer than the diameter of its end face, and is particularly intended to improve the surface magnetic field at its working face. This invention is
It is suitable for applications requiring a long and thin magnetic working surface, and is particularly advantageous for use in, for example, magnets for length measuring machines, torque magnets for outer rotor type motors, and the like.

0002

2. Description of the Related Art Until now, rare earth or ferrite sintered magnets or synthetic resin magnets have been mainly used as magnets for this type of use. Among the above-mentioned magnets, those with particularly strong surface magnetic fields and excellent attraction are rare-earth sintered magnets and synthetic resin magnets.Compared to these, ferrite-based sintered magnets have somewhat lower performance, Synthetic resin magnets have considerably inferior performance, and each has been used depending on its purpose. In other words, expensive rare earth magnets have been used for high-grade applications, and low-cost ferrite magnets have been used for low-grade applications, but in either case, the orientation direction of magnetic particles is isotropic or in the thickness direction, and the magnetic properties depend on the raw materials used. It was determined only by the goodness or badness of Among these, ferrite-based synthetic resin magnets have the advantage of being easily molded into complex shapes, being lightweight and capable of being molded in one piece, but their use has been limited due to the magnet's low surface magnetic field. .

0003

[Problems to be Solved by the Invention] The present invention advantageously solves the above problems, and provides novel magnetic powder particles that can obtain a strong surface magnetic field on the working surface even when ferrite magnetic powder is used. The purpose is to propose a long magnet with an oriented structure.

0004

[Means for Solving the Problems] That is, the present invention forms an action area in which the orientation direction of magnetic powder particles is focused in a contour line portion in a cross section that crosses the longitudinal direction of a long magnet, and It is a focused orientation type long magnet arranged in a row in the direction. Furthermore, by forming the magnet from a flexible synthetic resin material, it is advantageous because the applications can be further expanded.

As the long magnet of the present invention, both synthetic resin magnets and sintered magnets can be used. As magnetic powder for synthetic resin magnets and sintered magnets, any conventionally known magnetic powder can be used, such as ferrite magnetic powder, alnico magnetic powder, and rare earth magnetic powder such as samarium-cobalt magnetic powder and neodymium-iron-boron magnetic powder. Regarding its particle shape, the average particle size is about 1.5 μm, and the compressed density is 3.20.
The above are preferred.

[0006] As for the synthetic resin, any conventionally known synthetic resin can be used, and representative examples thereof are as follows. Polyamide-based synthetic resins such as polyamide-6 and polyamide-12. Single or copolymerized synthetic resins such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate, polystyrene, polyethylene, and polypropylene. polyurethane, silicone,
Synthetic resins such as polycarbonate, PBT, PET, polyetheretherketone, chlorinated polyethylene and Hypalon. Rubbers such as neoprene, styrene butadiene and acrylonitrile butadiene. Epoxy resin. Phenolic synthetic resin. Furthermore, the blending ratio of magnetic powder and synthetic resin as a binder is 60 to 70 vol.
It is desirable to set it as %. In addition, it goes without saying that conventionally used plasticizers, antioxidants, surface treatment agents, etc. can be used in appropriate amounts depending on the purpose, and plasticizers are particularly effective in imparting flexibility. Examples of plasticizers include phthalic acid ester plasticizers such as dioctyl phthalate (DOP) and dibutadyl titalate (DBP), adipic acid plasticizers such as dioctyl adipate (DOA), and polymeric plasticizers such as polyester. Molecular plasticizers etc. can be used.

[0007]

[Operation] FIG. 1 shows a long magnet in which magnetic powder particles are oriented according to the present invention. The arrow in the figure indicates the orientation direction of the magnetic powder particles, and the orientation of the magnetic powder particles is at the contour line in the cross section perpendicular to the longitudinal direction of the long magnet 1, that is, at the center of one long side of the rectangle in the illustrated example. A working area 2 converging in direction is formed, and this working area 2 is connected in the longitudinal direction. Therefore, when compared with the conventional long magnet shown in Figure 2,
In contrast to this conventional magnet, there is wasted magnetic flux.
In the elongated magnet of the present invention shown in FIG. 1, all the magnetic flux is focused in the active area, so a higher surface magnetic field can be obtained.

It is desirable that the orientation angle of the magnetic powder particles, indicated by α in FIG. 1, be about 10 to 70 degrees, preferably about 20 to 60 degrees. This is because if the orientation angle α is smaller than 10°, the effect of improving the surface magnetic field will be poor, while if it is larger than 70°, the effective surface area on which the surface magnetic field will appear will be significantly narrowed, and it will be reduced depending on the magnet's intrinsic coercive force. This is because it may become magnetic.

[0009] In the above example, the case where the end face shape of the elongated magnet is rectangular was mainly explained, but the magnet shape is not limited to this case, and may be as shown in Figs. 3(a) to (e). , trapezoid, triangle, polygon, circle, or semicircle.
), a plurality of action areas may be formed, and in short, an action area where the orientation direction of the magnetic powder particles is focused is formed in at least a part of the contour line in a cross section that crosses the longitudinal direction of the elongated magnet. It is sufficient that the action areas are continuous or intermittently continuous in the longitudinal direction.

[0010] The present invention aims to improve the surface magnetic field on the surface of the magnet in use by controlling the orientation direction of magnetic powder particles in the elongated magnet. Therefore, FIG. 4 illustrates the magnetic particle orientation procedure according to the present invention. In the figure, number 3 is the cavity provided in the magnetic field orientation mold, 4 is the magnetic pole,
5 is an opposing magnetic pole, 6 is an excitation coil, and 7 is a return yoke of the magnetic circuit. Note that by making each magnetic pole a permanent magnet, it is also possible to omit the excitation coil. Then, a synthetic resin magnet containing magnetic powder and synthetic resin in a predetermined ratio is inserted into the cavity 3, and when a magnetic field is applied while extruding the synthetic resin magnet as shown in FIG. Lines of magnetic force 5 are generated in the direction shown by the arrow, and magnetic powder particles are oriented along these lines of force 5. By converging the orientation direction of the magnetic particles in the active area in this way, the magnetic flux can be narrowed down, and as a result, the surface magnetic field in the active area can be significantly improved.

Incidentally, the magnetic pole 4 of the magnetic field orientation mold,
As the ferromagnetic material used for the opposing magnetic pole 5 and the return yoke, carbon steel such as S55C, S50C, S40C, SKD
Die steels such as No. 11 and SKD61, other materials such as pamendur and pure iron can be used, but it is more advantageous to perform surface hardening treatment to improve wear resistance. Non-magnetic materials to fill around the magnetic poles include stainless steel, copper-beryllium alloy, high manganese steel, bronze, brass, and non-magnetic super steel N.
-7 and the like are advantageously suitable, and it is advantageous to subject these to surface hardening treatment if necessary to improve wear resistance.

0012

[Example] Using the magnetic field orientation mold shown in Fig. 4,
It has the shape shown in , and its dimensions are width: 14mm, thickness: 3m
m and length: 125 mm, and the width of the action area is 8
A long magnet having a length of mm was molded under the following conditions. Raw materials/magnetic powder particles Magnetic powder A: Ferrite magnetic powder (magnetoplumbite strontium ferrite with average particle size of 1.5 μm) Magnetic powder B: Samarium-cobalt magnetic powder (Sm2Co17 type; average particle size of 10 μm) Synthetic resin: Chlorinated polyethylene/plastic Agent: DOP (dioctyl phthalate) / Others: polyethylene wax TTS (isopropyl triisostearoyl titanate)

Blend/Blend A (Plamag blend) Magnetic powder A: 61.5 vol% Chlorinated polyethylene: 25.5 vol% DOP: 12
vol% polyethylene wax: 0.5 vol%TTS: 0
．． 5 vol% ・Blend B (sintering mixture) Magnetic powder: 40 wt% Water: 60 wt%

Molding conditions/extrusion molding conditions Pellet composition used: Composition A Heating cylinder temperature: 160°C Discharge speed: 2 m/min Extruder: Full flight type (cylinder length)/(inner diameter) = 22 Compression ratio 3 Excitation coil magnetomotive force : 10000 A*Turn land area magnetic field application width: 70mm ・Compression molding conditions Raw materials used: Mixture B molding method: Injection method excitation method: Vertical magnetic field molding Molding temperature: 20°C Firing temperature: 1250°C

The surface magnetic field after magnetization of the long magnet thus obtained and the starting torque (motor characteristics) of the synthetic resin magnet were investigated.

The motor characteristics were evaluated using the rotor yoke 10 of the flat type motor shown in FIG. It was rolled up inside and used to measure the starting torque. In addition, in the same figure, the code 11
is the upper case, 12 is the back yoke, 13 is the shaft,
14 is a stator yoke, and 15 is a lower case.

The evaluation conditions are as follows. ・Magnet Outer diameter: 40mm Inner diameter: 34mm Thickness: 3mm Magnetization: 8 poles ・Drive method　　　　　　　3 phase Voltage: 12V Current: 200mA/phase 8 poles

As a comparison, a long magnet with similar external dimensions but oriented in the thickness direction without an active area in which magnetic powder particles were focused and oriented was manufactured and evaluated in the same way. The above evaluation results are shown in Table 1.

[0019]

[Table 1]

As is clear from Table 1, all of the long magnets obtained according to the present invention have a significantly improved surface magnetic field on the working surface compared to those obtained according to the conventional method, and the long magnets obtained according to the present invention have a significantly improved surface magnetic field on the working surface. It was confirmed that torque characteristics could also be improved.

[0021]

Thus, according to the present invention, it is possible to provide a long magnet having a much higher area of action of the surface magnetic field, which greatly contributes to expanding the range of application of this type of magnet.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a long magnet according to the present invention.

FIG. 2 is a schematic diagram of a conventional elongated magnet.

FIG. 3 is a schematic diagram showing an end face of a long magnet.

FIG. 4 is a schematic diagram of a magnetic field orientation mold.

FIG. 5 is a schematic diagram showing the procedure for extrusion molding.

FIG. 6 is a schematic diagram of a motor.

[Explanation of symbols]

1 Long magnet 2 Area of action 3 Cavity 4 Magnetic pole 5 Opposing magnetic poles 6 Excitation coil 7 Return yoke 8 Stator 9 Rotor 10 Rotor yoke 11 Upper case 12 Back yoke 13 Shaft 14 Stator yoke 15 Lower case

Claims (2)

[Claims] 1. A focused and oriented magnet, in which an action area in which the orientation direction of the magnetic powder particles is focused is formed in a contour portion of a cross section that crosses the longitudinal direction of the elongated magnet, and the action areas are connected in the longitudinal direction. Measure magnet. 2. The focused orientation type elongated magnet according to claim 1, which is made of a flexible synthetic resin material.