JPH04152602A - Malleable fe-cr-co permanent magnet and manufacture thereof - Google Patents

Abstract

PURPOSE:To make it possible to press-fit other members and to use the title permanent magnet as various kinds of sensors by a method wherein, after an aging treatment has been conducted on the press-fit expected section of the Fe-Cr-Co permanent magnet, malleability is given to the permanent magnet by conducting a heat-softening treatment at the temperature exceeding the re-aging temperature. CONSTITUTION:The large-calibered part 1b of a flat and cylindrical Fe-Cr-Co permanent magnet 1, on which a liquefying treatment and an aging treatment are conducted after it has been formed into the required shape, is dipped in a cooling container 11 containing a chemical solution and the like. A high frequency oscillation coil 12 is arranged on the outer circumferential part of the small-calibered part 1a, and a current of 100 to 200A or thereabout is applied to the coil 12 for 5 to 20 seconds. As a result, the small-calibered part 1a can be heated up to the temperature of liquefying treatment in a short period, and the large- calibered part 1b can be maintained at the aging treatment temperature or lower. The small- calibered part 1a of the heated part only is softened, malleability is given to it, press-fitting integration with other member can be made possible, and the intrinsic magnetic characteristics of the Fr-Cr-Co permanent magnet can be manifested by the large-calibered part 1b which is maintained in a cool state.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of Application The present invention allows Fe-Cr-Co permanent magnets to be used by fitting and press-fitting them into other members, making it easy to apply them to speed sensors for automobiles. Regarding Fe-Cr-Co permanent magnets, which can be used in a wide range of applications, such as various sensors, by heating and softening only the part scheduled to be press-fitted into other parts at a temperature exceeding the aging treatment temperature, it is possible to reduce the temperature lower than the magnetic pole forming part. The present invention relates to a Fe-Cr-Co permanent magnet with hardness and malleability, and a method for manufacturing the same.

Conventional technology Permanent magnets have traditionally been used in various types of sensors, especially F.
Since e-Cr-Co permanent magnets are easy to plastically work and cut and have excellent formability, they are often used in fields that require complex shapes and miniaturization.

For example, as shown in Fig. 5, a flat cylindrical Fe-Cr-C
O-based permanent magnets are used in automotive speed sensors.

That is, a flat cylindrical Fe-Cr-Co permanent magnet (
1) is arranged in a bearing (3) fixed to a shaft (2) which rotates in conjunction with the axle.

The bearing (3) consists of an inner ring (3a) fixed to the shaft (2) and steel balls (
The Fe-Cr-Co permanent magnet (1) is composed of an outer ring (3b) which is fixed to another member via a ring (3c), and an inner ring (3b).
3a) using screws or adhesive (not shown), and the magnetic field detection sensor (4) is made of Fe-
It is fixed through the outer ring (3b) so as to be disposed close to the magnetic pole face (outer peripheral surface) of the Cr-Co permanent magnet (1).

In the above configuration, the rotation of the flat cylindrical Fe-Cr-Co permanent magnet (1) is detected by the magnetic field detection sensor (4), and the speed of the vehicle can be directly measured.

Problems to be Solved by the Invention As mentioned above, Fe-Cr-Co permanent magnets are easy to plastically work and cut, but since the entire magnet hardens after being subjected to aging treatment, these processes are difficult. This is carried out before solution treatment or aging treatment to obtain the required magnetic properties.

When it is assumed that the aged Fe-Cr-Co permanent magnet will be directly fitted or press-fitted into another member, in the example shown in Fig. 5, it will be fitted or press-fitted into the inner ring (3a) constituting the bearing (3). In this case, it is necessary to finish each other to the required dimensions with high precision.

In other words, the tightening allowance is more than necessary (in the example shown in Fig. 5, (tightening allowance) = (outside diameter of the inner ring (3a)) - (Fe-C before press-fitting)
r-C.

If the press-fitting part inner diameter of the permanent magnet (1) is large, the Fe-Cr-Co permanent magnet will break during fitting or press-fitting, and if the tightening margin is small, the required bonding force will not be obtained.

In general, the internal diameter accuracy of Fe-Cr-Co permanent magnets cannot be finished to a very high degree of precision due to press variations during molding and deformation during heat treatment such as solution treatment and aging treatment. For large-scale mass production, Fe-
It has not been practiced to integrate Cr--Co permanent magnets with other members by press-fitting.

In order to integrate the Fe-Cr-Co permanent magnet with another member, it is necessary to fix it to the member using screws or adhesive, as in the case of the speed sensor described above. However, compared to the press-fitting method, these methods are very complicated, are not suitable for mass production, and increase the weight of the entire sensor part, so it is desirable to improve these integral fixing techniques. It was rare.

In view of the above-mentioned problems, the present invention aims to provide a Fe--Cr--Co permanent magnet that can be integrated with other members by press-fitting.

Means for Solving the Problems This invention was developed as a result of various studies on the properties of the planned engineering college area with the aim of solving the above problems.
After aging the part of the Co-based permanent magnet intended for engineering, it is heated and softened again at a temperature exceeding the aging treatment temperature to make it malleable, making it possible to press-fit it into other parts.
The present invention was completed based on the finding that the other parts originally had the magnetic properties of a Fe-Cr-Co permanent magnet and could be applied as various sensors.

That is, the present invention provides an Fe-Cr-Co permanent magnet which is integrated into another member and is characterized in that the hardness of the intended part of the Fe-Cr-Co permanent magnet is lower than the hardness of the magnetic pole forming part and has malleability. -Co-based permanent magnet.

In addition, after solution treatment and aging treatment, this invention maintains at least the magnetic pole forming part at a temperature below the aging treatment temperature, and at the same time maintains the part intended for the engineering university to be integrated with other members at a temperature exceeding the aging treatment temperature. Fe-C having malleability, characterized in that it is heat-softened and imparts low hardness and malleability only to the above-mentioned engineering section.
This is a method for manufacturing an r-Co permanent magnet.

Function The present invention can be applied to any known Fe-Cr-Co permanent magnet.

That is, the main components are 3 to 35 wt% Co, 1
It consists of 0 to 40 wt% Cr, the balance substantially Fe, and contains one or more additional elements such as Ni, Ti, V, W, Zr, Mo, etc., if necessary. Preferably,
It consists of 10 to 20 wt% Co, 25 to 30 wt% Cr, and the remainder substantially Fe, and if necessary, contains one or more additional elements of 1 wt% or less.

In addition, in this invention, the shape of the Fe-Cr-Co permanent magnet is not limited to one embodiment described below, and may be appropriately selected depending on the application, the shape of other members, etc., but especially when press-fitting with other members. It is desirable that the part has a cylindrical shape, such as a cylindrical shape, a rectangular cylindrical shape, etc., depending on the shape of the press-fitted part of the other member.

Usually, Fe-Cr-Co permanent magnets have the above composition selected according to the required magnetic properties, and undergo melting, agglomeration, hot working,
It is molded into the desired shape through softening treatment and cold working processes.

Thereafter, solution treatment and aging treatment are performed to achieve the required magnetic properties, but if necessary, to obtain an anisotropic magnet, heat treatment in a magnetic field is performed before aging treatment.

The present invention is characterized in that after the above steps are completed, only the portion to be press-fitted is heated at a temperature exceeding the aging treatment temperature to return it to the state before the aging treatment.

That is, although the magnetic properties of the portion heated at a temperature exceeding the aging treatment temperature are significantly degraded, on the other hand, the workability before the aging treatment can be obtained. Therefore, the parts other than the part to be press-fitted (heated part) need to be kept below the aging treatment temperature in order to maintain the originally required magnetic properties. It is desirable to actively cool down using various refrigerants.

From the above, if the heating temperature exceeds the aging treatment temperature, the workability before aging treatment can be imparted, but Fe-C
The degree of softening varies depending on the composition range of the r-Co permanent magnet, the size and shape of the part to be press-fitted, etc., and in order to obtain the required malleability, the optimum processing temperature and processing time must be determined, taking into account tightening margins, etc. It is desirable to select

That is, if the treatment temperature is low, a long treatment time is required, which is not very efficient, and it is also difficult to maintain the temperature at or below the aging treatment temperature for a long time in areas other than the area scheduled for engineering. In addition, if the temperature is higher than necessary, it will be difficult to maintain other parts below the aging treatment temperature, so in order to efficiently heat soften in a short time, the heating temperature should be the same as the solution treatment temperature. is desirable.

Usually, the solution treatment temperature is about 850°C to 1300°C, and the aging treatment temperature is in the range of 500°C to 750°C, and multistage treatment is performed. The treatment time for each treatment is approximately 10 minutes to 1.5 hours for solution treatment and approximately 5 hours to 40 hours for aging treatment. In addition, if necessary, 600°C to 750°C before aging treatment.
Heat treatment is performed in a magnetic field for about 30 minutes to 1.5 hours within the range of .

In this invention, the aging treatment temperature is defined as the final temperature of the aging treatment, regardless of the presence or absence of heat treatment in a magnetic field.

That is, when aging treatment is performed by lowering the temperature in multiple stages, for example between 750°C and 500°C after solution treatment,
The aging treatment temperature in this invention is 500°C, which is the final temperature.
℃.

Various methods can be adopted for the above partial heating, but
It is desirable to make a selection in consideration of the shape and dimensions of the heated part, the heating temperature, the method of cooling other parts than the heated part, etc. In particular, when a heat transfer heating method is adopted, the temperature of parts other than the required portions is likely to be heated to a temperature exceeding the aging treatment temperature. Therefore, it is desirable to employ a high frequency induction heating method as shown in Examples described later.

Fe-Cr-C obtained by the production method of the present invention.

In the system permanent magnet, the hardness of the part to be press-fitted becomes smaller than that of the magnetic pole forming part by partial heating of the above-mentioned required parts, so that the malleability of the part to be press-fitted is superior to that of the magnetic pole forming part, and it is difficult to use other parts. It becomes possible to press fit into the

According to the inventor's experiments, the hardness of the magnetic pole forming part is between Hv400 and Hv450, although it varies somewhat depending on the composition, heat treatment conditions, etc.
However, the hardness of the press-fit part is Hv200~35
It was possible to adjust it to about 0.

In addition, by setting such hardness, the malleability of the part to be press-fitted is significantly improved, and according to the measurement method shown in the examples described later, it was confirmed that it has an elongation of 1% or more,
Furthermore, the pressure during press-fitting is relatively small, allowing efficient press-fitting.

Disclosure by Drawings FIGS. 1a and 1b are a partial longitudinal sectional view and a plan view showing an embodiment of a Fe-Cr-Co permanent magnet having a malleable cylindrical press-fit portion according to the present invention.

FIGS. 2 and 3 are partial vertical cross-sectional explanatory views showing an embodiment of the method for manufacturing the Fe-Cr-Co permanent magnet shown in FIG.

The Fe-Cr-Co permanent magnet of the present invention shown in Fig. 1 (
1) is used in the automobile speed sensor shown in Fig. 5, and is made of a flat cylindrical shape, and has a small diameter part (1a) that has excellent malleability and is the expected size with other parts, and a required magnetic field. A large diameter part (1
b) It consists of. The small diameter portion (1a) has a hardness of about Hv250 according to a method described later, and has an elongation of 0.3% or more.

Fe-Cr-Co permanent magnet (1) having such properties
As shown in FIG. 5, the inner ring (3a) constituting the bearing (3) is directly press-fitted onto the shaft (2) without using any conventional screws or the like without causing any cracks.

The method for manufacturing the Fe-Cr-Co permanent magnet (1) according to the present invention will be described in detail with reference to FIGS. 2 and 3.

After being formed into the desired shape using a known method, solution treatment is performed.
Flat cylindrical Fe-Cr-C that has been subjected to aging treatment.

As shown in Fig. 2, the large diameter part (1b) of the system permanent magnet (1) is located in a cooling container (10) containing a refrigerant (10) such as water or medicine.
11) A high frequency oscillation coil (12) is placed on the outer periphery of the exposed small diameter portion (1a), and a current of about 100A to 200A is applied to the coil (12) for 5 seconds to
By applying electricity for about 20 seconds, the small diameter portion (1a) can be heated to a temperature higher than the solution treatment temperature in a short time, and the large diameter portion (1b) can be maintained at a temperature lower than the aging treatment temperature. In the configuration shown in FIG. 2, it is desirable to have a configuration in which the refrigerant (10) can be continuously supplied into the cooling container (11) so that the refrigerant (10) does not vaporize during heating and reduce the cooling capacity. Further, the coil (12) is configured to be pipe-shaped and can be water-cooled.

In addition, in the configuration shown in FIG. 3, the large diameter part (1b) of the flat cylindrical Fe-Cr-Co permanent magnet (1) has a plurality of water distribution holes (21) inside, and a man-made vibrator (22 in 22). ), and a high-frequency oscillation coil (12) is placed on the outer periphery of the small diameter portion (1a).

As shown in Figures 2 and 3, the flat cylindrical Fe-Cr-C
.

System permanent magnet (1 off-shore press-fit planned part, i.e. small diameter part (1a)
If the other parts, namely the large diameter part (1b), are heated to a temperature exceeding the aging treatment temperature (solution treatment temperature in the above case) and at the same time kept below the aging treatment temperature, the small diameter part (1b) of the heated part ( Only 1a) is softened and given malleability,
Press-fit integration with other members is possible, and the cooled and maintained large diameter portion (1b) can exhibit the magnetic properties originally possessed by Fe-Cr-Co permanent magnets.

Example 10.3wt%Co, 26wt%Cr, 0.4wt%T
i. Blend the raw materials so that the remainder is substantially Fe, and dissolve;
By agglomeration, hot working, softening treatment, and cold working, a flat cylindrical Fe-Cr-Co permanent magnet material was obtained as shown in FIG.

Then, following solution treatment at 920°C for 60 minutes,
An aging treatment consisting of a multistage treatment of 50°C to 500°C for 30 hours was performed to obtain an isotropic flat cylindrical Fe-Cr-Co permanent magnet.

Furthermore, by the method shown in Fig. 2, a high-frequency oscillation coil (
12) for 15 seconds to apply a current of 15OA to the small diameter part (1
a) was heated. At this time, the temperature of the small diameter part (1a) is 950
'C.

On the other hand, the large diameter portion (1b) was immersed in a refrigerant (10) made of Icenon (trademark) and maintained at a temperature below the aging treatment temperature.

The temperature of the large diameter portion (1b) at the end of heating was 200°C or less.

By the above method, the target dimensions are: thickness 0.8 mm, small diameter part inner diameter 48.1 mm, height 34 mm, and large diameter part inner diameter 55 m.
A plurality of flat cylindrical Fe-Cr-Co permanent magnets each having a height of 5 mm and a height of 5 mm were obtained.

In addition, a plurality of Fe-Cr-Co permanent magnets were prepared as comparative examples without performing the above-mentioned heat treatment and under all other conditions similar to those of the flat cylindrical Fe-Cr-Co permanent magnet of the present invention.

Each of these Fe-Cr-Co permanent magnets was subjected to a press-fitting test as shown in FIG. 4, and the effects of the present invention were confirmed.

That is, the flat cylindrical Fe-Cr-Co permanent magnet (1) is placed on the upper surface of the magnet support (30), and the inner diameter (
The small diameter portion (1a) of the magnet has an outer diameter (Do
) with different cylindrical members (31) are pressed at the tip end (3
2), and the occurrence of cracks was investigated.

Uni, the small diameter part of the Fe-Cr-Co permanent magnet (1)
1a) As shown in the figure, the inner diameter (Dl) is the dimension of the tip, and is the average value of the measured values in the X direction and the Y direction, respectively. Normally, when a Fe-Cr-Co permanent magnet (1) having the shape shown in the figure is press-molded, the size of the tip of the subtotal part is the smallest.

The outer diameter dimension (DO) of the cylindrical member (1b) is gradually changed, and the maximum outer diameter dimension (Dmax) of the cylindrical member when a crack occurs in the small diameter portion (1a) of the planned press-fitting part is measured. The elongation of part (1a) was confirmed.

Here, elongation is assumed to be elongation (%)=(Dmax-DI)/DIXnX100 when Dmax-Dl is the tightening margin.

Fe-Cr-C obtained by the production method of the present invention.

The system permanent magnet (1) had an elongation of 1% or more, and the required bonding force was obtained without cracking.

The dimensions of the sample used are Dmax - Dl = 150 to 165 pm.

However, all of the samples of comparative examples in which the predetermined heat treatment was not performed on the part to be press-fitted cracked at full size.

Moreover, Fe-Cr obtained by the manufacturing method of the present invention
The hardness of the small diameter part (1a) of the -Co permanent magnet (1) is about Hv250 to 260, and the hardness of the large diameter part (1b)
The hardness was about Hv385-400.

Furthermore, when the magnetic properties (surface Bg) of the magnetic pole part formed in the large diameter part (1b) were measured, similar magnetic properties were shown for both the magnet of the present invention and the comparative example.

Effects of the Invention In general, when Fe-Cr-Co permanent magnets are industrially mass-produced, the variation in the inner diameter (Dl) of the small diameter portion (1a) of the part to be press-fitted becomes even larger due to press variations, deformation during heat treatment, etc. Because there are large variations in the actual tightening margin and variations in the outer diameter of other parts to be press-fitted, it is possible to use Fe-Cr-Co permanent magnets without cracking on a mass production scale. In order to employ the press-fitting method, the desired press-fitting area is required to have great malleability.

As shown in the examples, the Fe-Cr-Co permanent magnet of the present invention has a large elongation at the press-fitting portion, and can have a large tightening margin. In the example, the inner diameter (Dl) of the small diameter portion (1a) is determined as an average value, but the variation is 5.
It was about μm to 30 pm.

In this invention, only a part of the Fe-Cr-Co permanent magnet, that is, the part to be press-fitted, has malleability, so that it is possible to adopt a press-fitting method as a means of integrating with other parts, and the applicable range is as follows. Since the magnet can be expanded and a press-fitting method can be used, the shape of the permanent magnet can be simplified, eliminating the need for screwing or gluing, improving mass productivity and reducing the weight of the device.

[Brief explanation of the drawing]

FIGS. 1a and 1b show an F having a malleable cylindrical part according to the present invention.
FIG. 2 is a partial vertical cross-sectional view and a plan view showing an example of an e-Cr-Co permanent magnet. FIGS. 2 and 3 are partial longitudinal cross-sectional explanatory views of a heating and cooling device showing an embodiment of the method for manufacturing the F6-Cr-Co permanent magnet shown in FIG. 1. FIG. 4 is an explanatory diagram of a jig used in a test method for confirming the effect of the Fe-Cr-Co permanent magnet shown in FIG. FIG. 5 is a partial vertical cross-sectional explanatory view showing a speed sensor for an automobile using a Fe-Cr-Co permanent magnet. 'J--Fe-Cr-Co permanent magnet, 1a...small diameter part, 1b...large diameter part, 2...shaft, 3...bearing, 3
a...Inner ring, 3b...Outer ring, 3c...Steel ball, 4...
Magnetic field detection sensor, 10... Refrigerant, 11... Cooling container, 12... High frequency oscillation coil, 20... Cooling plate, 21... Water distribution hole, 22... Pipe, 23... Circular groove, 3o... Magnet support, 31... Cylindrical member, 3
2...Press tip

Claims (1)

[Scope of Claims] 1. An Fe-Cr-Co permanent magnet that is press-fitted into another member and is characterized in that the hardness of the part to be press-fitted is lower than the hardness of the magnetic pole forming part and has malleability. Cr-Co permanent magnet. 2. After solution treatment and aging treatment, at least the magnetic pole forming part is maintained at a temperature below the aging treatment temperature, and the part to be press-fitted to be integrated into another member is heated and softened at a temperature exceeding the aging treatment temperature, Fe-C having malleability characterized by imparting low hardness and malleability only to the portion to be press-fitted.
A method for manufacturing an r-Co permanent magnet.