JPH02305A - Plastic magnet - Google Patents

Abstract

PURPOSE:To facilitate manufacturing process by forming a magnet for motor in a unified body by injection molding method, aligning the axes of easy magnetization biaxially, and then performing magnetizing process. CONSTITUTION:A magnetic pole core 21 of a columnar type with a step is installed at the center of a molding tool 15; an electromagnet coil 22 is arranged on the external periphery of the core 21; in order that magnetic flux induced by the coil 22 may form a path in the arrow mark direction, mold members 20, 23, 24 composed of ferromagnetic substance are arranged on the periphery of the coil 22. In order to form a plastic magnet, mixture of magnetic powder and organic material is firstly injected into the opening part of a spool 29 via a nozzle 30. Said mixture is filled in a molding space 27 passing through a runner 28. Axes of easy magnetization of magnet powder particles in the mixture are aligned in two directions by magnetic field formed biaxially in the space 27, and then subjected to magnetizing process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arcuate or annular plastic magnet that can be used as a magnetic field for a control motor used in various electronic devices and industrial devices.

Motors used to control various types of equipment often require strict precision in rotational speed. In order to improve the accuracy of these motor characteristics, it is necessary to provide a function that constantly detects the rotational speed and performs feedback control. is necessary.

Therefore, in the past, a ring-shaped motor drive magnet with magnetic properties magnetized in the radial direction and a ring-shaped rotation detection magnet with magnetic properties magnetized in the perpendicular direction to the radial direction were manufactured separately. A method using two magnets separated from each other and a method using the two magnets bonded together have been used.

FIG. 1 is a sectional view showing a conventional magnet used in control motors of various devices, in which a magnet 1 is a motor drive magnet 2 having magnetic properties magnetized in the radial direction Ml of a ring body. Said radial direction M! A rotation detecting magnet 3 having magnetic properties magnetized in the perpendicular direction M2 is integrally formed with an adhesive 4 or the like, and its outer shape is concentric.
A ring shape adhesively molded onto the body (see Fig. 1(a)) or a ring shape with flanges where both magnets have different ring widths (see Fig. 1(a)) are available.
b)) etc. are widely known.

However, in the magnets used in conventional control motors, the motor drive magnet and the rotation detection magnet are manufactured separately and then glued together, resulting in the following problems: There was a point.

(a) It is necessary to separately manufacture two types of magnets with different magnetization directions in advance, resulting in a large number of parts and troublesome parts management. (b) In order to keep the dimensional accuracy within the required tolerance, After bonding and integrating the two pre-processed magnets, including the finishing allowance, it is necessary to perform precision processing such as cutting again. (d) Increases manufacturing man-hours and lowers material yield;
This had problems such as increasing manufacturing costs.

The present invention has been made to solve the above-mentioned problems, and the motor magnet is integrally molded by injection molding or the like, and the magnet is magnetized after aligning the axis of easy magnetization in two directions. Accordingly, it is an object of the present invention to provide an inexpensive integrated two-way plastic magnet that is easy to manufacture and has a high raw material yield.

That is, the plastic magnet according to the present invention is made by bonding magnet powder with resin and integrating it, and has a radially magnetized part that is arcuate or annular and magnetized in the radial direction.
It is characterized by having two types of magnetized parts: a generatrix direction magnetized part which is arcuate or annular and magnetized in a direction perpendicular to the radial direction.

Hereinafter, embodiments of the plastic magnet according to the present invention will be specifically described.

FIG. 2 is a longitudinal cross-sectional view showing one embodiment of the plastic magnet according to the present invention, and the plastic magnet 10 is formed by integrally molding a mixture of magnet powder and an organic substance by a molding method such as an injection molding method. As shown in Fig. 1, an annular radial magnetized section 11 and an annular generatrix direction magnetized section 12 having a seven-flange shape protruding from the outer periphery of the lower end of the radial magnetization section 11 are integrally formed by integral molding. It is equipped with two types of magnetized parts. In the plastic magnet 10 integrally molded into the above-mentioned predetermined shape, the axis of easy magnetization of the magnet 10 is located at the radial magnetized portion 1.
In the case of an integrally molded motor magnet, the magnets are arranged in the radial direction Ml in 1, or in the direction M2 perpendicular to the radial direction Ml in the generatrix direction magnetized part 12, and are magnetized in two directions. A radial direction magnetized section 11 that is magnetized in the radial direction M1 and serves as a motor drive magnet, and a generatrix direction magnetized section 12 that is magnetized in the direction M2 perpendicular to the radial direction and serve as a rotation detection magnet are integrated. It is something.

Furthermore, the plastic magnet 10 according to the present invention has a magnetic property (Ml) of the radial direction magnetized part 11 and a generatrix direction magnetized part 12.
It includes those that have almost the same magnetic properties (M2) and have higher magnetic properties than the isotropic magnet of the non-magnetic field molded product, but have different magnetic properties in the two directions, and It also includes a plastic magnet whose magnetic properties in at least one direction are higher than those of an isotropic magnet made of a non-magnetic field molded product. The plastic magnet 10 having each of these aspects can be widely used as a field magnet for various control motors.

FIG. 3 is a longitudinal sectional view showing another embodiment of the plastic magnet according to the present invention in a thick-walled ring-shaped magnet,
As shown in FIG. 1, this plastic magnet 10 is provided with a radially magnetized part 11 having magnetic characteristics magnetized in the radial direction M1 at the upper part of the ring-shaped magnet, and at the thick end of the outer periphery of the ring-shaped magnet. A generatrix direction magnetized portion 1 having magnetic characteristics magnetized in the direction M2 perpendicular to the radial direction M1 at
It is equipped with 4.

Therefore, the plastic magnet 10 configured in this way has two magnetic properties in the radial direction M1 and the perpendicular direction M2 perpendicular to the radial direction M1 in one magnet.
The dimensional accuracy of the product has been improved, the manufacturing cost has been significantly reduced, and the stability of magnetic properties can now be easily ensured.

Furthermore, the plastic magnet 10 according to the present invention having the above configuration is manufactured using a mold shown in FIG. 4 as an example.

This mold 15 can be divided into an upper mold 18 and a lower mold 19. A stepped cylindrical magnetic pole core 21 with a narrower diameter at the upper part is provided at the center of the mold 15. An electromagnetic coil 22 is disposed on the outer circumferential side, and mold members 20 and 23 made of a ferromagnetic material are placed around the electromagnetic coil 22 so that the magnetic flux induced by the electromagnetic coil 22 forms a path in the direction of the arrow shown in the figure. .24 each.

Further, a non-magnetic member 25 is disposed within the mold member 23 between the electromagnetic coil 22 and the mold member 24, and a non-magnetic member 26 is disposed concentrically with the mold member 24. Further, a magnetic pole core 21, a mold member 23, 24, and a non-magnetic member 25.
26, a molding space 27 having the same shape as the flanged ring shown in FIG. 2 is formed. The non-magnetic member 25 placed on the upper surface of the electromagnetic coil 22 blocks the magnetic flux induced by the electromagnetic coil 22 and blocks the molding space 27.
This serves to guide magnetic flux in the perpendicular direction to the portion 27b that forms the generatrix direction magnetized portion 12, which has a flange shape. On the other hand, a non-magnetic member 26 placed on the upper surface of the molding space 27
0 or more, which functions to block the magnetic flux rising in the center of the magnetic pole core 21 and guide the magnetic flux in the radial direction to the portion 27a of the molding space 27 where the ring-shaped radially magnetized portion 11 is formed. By configuring the mold 15 in this manner, magnetic fields in two directions can be set within the same molding space 27.

The non-magnetic member 26 placed on the upper surface of the molding space 27 is provided with a runner 28 and a spool hole 29 passing through the runner 28 as an injection passage during injection molding.
At step 17, the upper mold 18 and the lower mold 19 are sandwiched and fixed and subjected to injection molding.

By devising the mold 15 as described above, the plastic magnet according to the present invention can be manufactured.

First, a mixture of magnet powder and organic material is injected into the opening of the spool 29 through the nozzle 30, passes through the spool 29 and the runner 28, and is filled into the molding space 27. The axes of easy magnetization of the magnetic powder particles in the mixture are aligned with magnetization in two directions by the magnetic fields formed in two directions in the molding space 27 described above, and then subjected to a magnetization process. A magnet integrally molded into a predetermined shape and magnetized in this way forms magnetic characteristics in two different directions.

Note that the injection-molded molded product is obtained by dividing the upper mold 18 and lower mold 19 of the mold 15, and then forming a protruding pin supported via a support plate 32 fixed to an ejector rod 31, as illustrated in the figure. By pushing up 32, the molded body that is in close contact with the magnetic pole core 21 can be taken out.

FIG. 5 is a longitudinal cross-sectional view showing an embodiment in which the flanged ring-shaped plastic magnet 10 shown in FIG. 2 is manufactured by pressure molding.
A protrusion 26a having the same shape as the opening 7 is provided.
After filling the molding space 27 with a mixture of magnet powder and organic matter, the protrusion 26a is inserted into the upper surface of the molding space 27 and pressure molding is performed. In this pressure molding as well,
As in the previous embodiment, the easy magnetization axes of the magnets are aligned in two directions at the same time as molding, and then magnetized in the two directions.

FIG. 6 is a longitudinal cross-sectional view showing an embodiment of manufacturing a magnet in which the axis of easy magnetization is arranged in two different directions and the magnetic properties in the two directions are different. By adjusting the thickness of the non-magnetic member 34 directly under the portion 27b that forms the flange-shaped generatrix direction magnetized portion 12 in the molding space 27, the molding space 27 It becomes possible to arbitrarily control the strength of the magnetic field in two directions formed within the corner so that the magnetic field at the portion '27'c forming a part of the corner becomes weak. Therefore, according to this example:
It becomes possible to manufacture various types of magnets in which the axes of easy magnetization are arranged in two different directions and the magnetic properties in the two directions are different.

FIG. 7 is a longitudinal cross-sectional view showing an embodiment in which the thick-walled ring-shaped magnet shown in FIG. Something,
The magnetic flux induced by the electromagnetic coil 22 is blocked to form a vertical magnetic circuit in the portion 27b of the thick end of the outer periphery of the molding space 27 where the generatrix direction magnetized portion 12 is molded.

By providing the non-magnetic member 35 in this way, it has become possible to manufacture the magnet according to the present invention even in a thick-walled ring-shaped magnet.

In the above detailed description of the present invention, an embodiment was shown using a ring-shaped annular magnet as an example, but the present invention is not limited to this shape, and it goes without saying that the present invention can also be applied to arc-shaped magnets and the like. Furthermore, although injection molding and pressure molding were shown as examples in the above embodiments, the present invention can also be applied to casting molding.

As described above, according to the present invention, magnet powder is integrated by bonding with resin, and has a radially magnetized portion that is arcuate or annular and magnetized in the radial direction, and a radially magnetized portion that is arcuate or annular and magnetized in the radial direction. The plastic magnet has two types of magnetized parts: a generatrix direction magnetized part magnetized perpendicular to the radial direction, and an integrated plastic magnet with the functions of two magnetic properties can be manufactured with high precision. It is possible to provide magnets with a high yield and is useful as a magnet used in control motors, and its effects are tremendous.

[Brief explanation of the drawing]

FIGS. 1(a) and 3(b) are longitudinal sectional views showing examples of the shape of magnets of conventional control motors, FIGS. 2 and 3 are longitudinal sectional views showing examples of the shape of plastic magnets according to the present invention, and FIGS. Figure 4 is an overall sectional view showing an example of a mold used in manufacturing the plastic magnet according to the present invention, and Figures 5 to 7 are molds used in other embodiments for manufacturing the plastic magnet according to the present invention. It is a principal part sectional view showing each pair of a mold. 10...Plastic magnet, 11...Radial direction magnetized part, 12.14...Generatrix direction magnetized part.偕

Claims (3)

[Claims] (1) Magnet powder is bonded and integrated with resin,
Two types of magnetized parts: a radial magnetized part that is arcuate or annular and magnetized in the radial direction, and a generatrix direction magnetized part that is arcuate or annular and magnetized perpendicular to the radial direction. A plastic magnet characterized by being equipped with. (2) The plastic magnet according to claim (1), wherein the magnetic properties of the radial direction magnetized part and the magnetic properties of the generatrix direction magnetized part are substantially the same. (3) The plastic magnet according to claim (1), wherein the magnetic properties of the radial direction magnetized part and the magnetic properties of the generatrix direction magnetized part are different from each other.