JPH0263104A - Multipolar magnet and manufacture of multipolar magnet - Google Patents

Abstract

PURPOSE:To obtain a multipolar magnet whose magnetic characteristic is excellent by a method wherein a ferromagnetic metal layer 4 is laid between a ring-shaped magnet and an umbrella-shaped rotor which has been attached collectively to the magnet and which is composed of a nonmagnetic material. CONSTITUTION:A ring-shaped magnet is attached to a peripheral face of a nonmagnetic umbrella-shaped rotor 1. A ferromagnetic metal layer 4 is laid between both. A multipolar magnetization operation is executed in a state that the ferromagnetic metal layer 4 has been brought into contact with the rear of the ring-shaped magnet as viewed from the side of a magnetizating head 3. Accordingly, a line of magnetic force emitted from the magnetizing head 3 during the magnetization operation can sufficiently pierce the ring-shaped magnet 2 because the ferromagnetic metal layer 4 exists; the magnetization operation can be executed satisfactorily. In addition, since a whole body of the umbrella-shaped rotor 1 is not constituted of a ferromagnetic metal whose specific gravity is large, a moment of inertia of a multipolar magnet does not become large when this magnet is turned.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a multipolar magnet suitable for use in magnetic encoders, frequency generators, etc., and a method for manufacturing the same.

Conventional technology A multipolar magnet suitable for applications such as magnetic encoders and frequency generators is made by integrating a ring-shaped magnet 2 on the circumference of an umbrella-shaped a-tattle made of a non-magnetic material, as shown in Fig. 2. It was installed. If this multipolar magnet has a large weight, the moment of inertia when rotating becomes large, which causes problems when used for speed control or the like. Therefore, it is necessary to make it as light as possible, and the umbrella-shaped rotor 1 is made of a non-magnetic material with low specific gravity such as die-cast aluminum or polyacetal resin.

Problem to be Solved by the Invention However, when performing multi-pole magnetization, as shown in FIG. This is carried out with the magnetizing head 3 facing the circumferential surface. Therefore, the lines of magnetic force coming out of the magnetizing head 3 return to the magnetic poles without sufficiently passing through the ring-shaped magnet 2, as shown by the dotted arrow.

As a result, a multipolar magnet with a large magnetic force has not been obtained, and in view of this point, an object of the present invention is to provide a multipolar magnet with excellent magnetic properties.

Means for Solving the Problems As shown in FIG. 1, the multipolar magnet according to the present invention includes a ring-shaped magnet 2 and an umbrella-shaped rotor 1 made of a non-magnetic material integrally equipped with the ring-shaped magnet 2. A ferromagnetic metal layer 4 is interposed therebetween.

Due to the presence of the working ferromagnetic metal layer 4, the lines of magnetic force coming out of the magnetizing head 3 sufficiently penetrate through the ring-shaped magnet 2, as shown by the dotted arrow in FIG. 1, and return to the magnetic pole. As a result, a multipolar magnet with excellent magnetic properties can be obtained.

Ferromagnetic metal has a large specific gravity and is heavy, but in the present invention, it is provided as a layer between the ring-shaped magnet 2 and the umbrella-shaped rotor 1.
Overall, the weight does not increase significantly, and the moment of inertia does not increase.

Example Next, the present invention will be explained in detail.

A ring-shaped resin magnet with an outer diameter of 6s+m is integrally attached to the outer peripheral surface of an umbrella-shaped aluminum rotor, and while it is rotated, it is magnetized by facing the ring-shaped resin magnet.6. y)'1
Flow m square wave LT,, Al1 = 148.17'.

Magnetization was performed on the outer peripheral surface of the ring-shaped resin magnet.

In Example 1, between the ring-shaped resin magnet and the umbrella-shaped rotor,
An iron layer was interposed as a ferromagnetic metal layer.

In Example 2, a layer of nickel was interposed. The conventional example is
This is a case where a ring-shaped resin magnet is directly integrally attached to an umbrella-shaped rotor without intervening a ferromagnetic metal layer.

Table 1 shows the measurement results of the reproduction output and surface magnetic force of a multipolar magnet whose outer peripheral surface was magnetized with 1440 poles.

Effects of the Invention As described above, the multipolar magnet according to the present invention has a ring-shaped magnet attached to the circumferential surface of a non-magnetic umbrella-shaped rotor, with a ferromagnetic metal layer interposed between the two. Multipolar magnetization is performed with the ferromagnetic metal layer in contact with the back surface of the ring-shaped magnet when viewed from the magnetization head side. Therefore, due to the presence of the ferromagnetic metal layer, the magnetic lines of force emitted from the magnetizing head during magnetization can sufficiently penetrate the ring-shaped magnet, allowing good magnetization to be performed. In addition, since the entire umbrella-shaped rotor of a multipolar magnet is not made of ferromagnetic metal with a high specific gravity, the moment of inertia does not increase when it is rotated, and its industrial value is extremely large. It is.

[Brief explanation of the drawing]

FIG. 3 is a cross-sectional explanatory diagram showing a polar magnet and a state in which multi-polar magnetization is applied. 1 is an umbrella-shaped rotor, 2 is a ring-shaped magnet, 3 is a magnetizing head, and 4 is a ferromagnetic metal layer.

Claims (2)

[Claims] 1. A ring-shaped magnet is attached to the circumferential surface of an umbrella-shaped rotor made of non-magnetic material, and a ferromagnetic metal layer is placed between the ring-shaped magnet and the umbrella-shaped rotor. Interposed multipolar magnet. 2. When rotating a ring-shaped magnet and applying multipolar magnetization to the circumferential surface of the ring-shaped magnet using a magnetizing head that faces the ring-shaped magnet, the circumference of the ring-shaped magnet on the opposite side of the ring-shaped magnet from the magnetizing head is A method for manufacturing a multipolar magnet, characterized by bringing a ferromagnetic metal layer into contact with a surface.