JPS59182947A - Production of fe-cr-co permanent magnet alloy - Google Patents

Abstract

PURPOSE:To produce an Fe-Cr-Co permanent magnet alloy at a high product yield by injection molding a mixture composed of Fe-Cr-Co alloy powder and a binder into a metallic mold connected concentrically with runners around a sprue. CONSTITUTION:Powder consisting of an Fe-Cr-Co permanent magnet alloy material is mixed or kneaded with a binder consisting of an org. compd., and the mixture thereof is injection-molded into a metallic mold. Plural runners 2a are connected concentrically and are provided around a sprue 1a in said metallic mold and are communicated respectively with cavities 4a. The width or inside diameter (d) of a gate 3a connected with the runners 2a is set at 5/100-1/2 of the inside diameter D of the runners 2a. The molding obtd. by such metallic mold is successively subjected to a binder removal and sintering, then to a heat treatment, by which the Fe-Cr-Co permanent magnet alloy is obtd. with a low rate of defectives.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves forming a permanent magnet alloy containing Fe, Cr, and Co as main components into a molded body by injection molding a mixture of the alloy material powder and a binder, and then removing the binder. , Fe-0r produced by sintering and heat treatment
The present invention relates to a method for manufacturing a -Co-based permanent magnet alloy.

In general, Fecrco-based permanent magnet alloys do not have nearly the same magnetic properties as -1-alnico magnets, but rather have the characteristics of easy machining. Because of this, various uses are attracting attention as 哄('l jrAfil).

On the other hand, powder metallurgy technology has been developed as a manufacturing method for general metal parts, and has been widely applied to the manufacturing of automobile parts, electrical equipment parts, mechanical parts, etc., and its effectiveness is well known.

Fe-Cr-(:, o-based permanent magnet alloys (hereinafter referred to as main alloys) are generally manufactured by melting and casting raw materials, and then hot working at about 1,000°C or higher as necessary to produce a
α phase homogenization treatment (solution treatment) is carried out at a temperature of 640℃ or above, followed by machining such as cutting and drilling as necessary after rapid cooling.Finally, in order to impart magnetic properties, The isothermal magnetic field treatment is further performed at an appropriate temperature of about 520 to 620°C.

In this way, water-based alloys can be used in commonly manufactured products (e.g., 49-20431, 5037011, JP-A-53-
109816, JP 53-14-2 = 0220, etc.), it has characteristics that are not required for alnico magnets, etc., but if powder metallurgy, that is, sintering, is applied to water-based alloys, The process from melting to solution treatment is powder mixing.

It becomes a culm that is extremely easy to mold and sinter, and can be used to obtain a magnet material with a desired shape, or can be finished into a shape close to the desired shape.

However, water-based alloy permanent magnet materials can be manufactured not only by the melt fs manufacturing method but also by ordinary press forming methods (for example, JP-A-56-139657, JP-A-57-16150).
Even when using the following publications, it is necessary to finish the material when manufacturing products with complex shapes or products that require a high degree of dimensional accuracy.

It is also being considered to manufacture water-based alloys by injection molding, but the molds of conventional injection molding equipment are generally
It is configured as shown in the figure.

In other words, since the runner 2 is formed in a skewer shape in both directions around the sprue 1, the flow of the hot water is not uniform, and the raw material 11 cannot be uniformly injected into each cavity, resulting in a low defect rate. There was a flaw in becoming a person.

The present invention eliminates these drawbacks and aims to provide a method for producing a water-based alloy that can be uniformly injection molded into each runner.

The structure of the present invention is to mix or knead a powder made of a water-based alloy with a binder, and then apply the mixture to a plurality of runners connected concentrically around a sprue, and to apply the mixture to a gate connected to the runner. A Fe Cr Co permanent magnet alloy that is injection molded in a mold whose width j: or inner diameter is set to 5,.../100-1/2 of the inner diameter of the runner, and then sintered after removing the binder. It's in the WA construction method.

That is, the method for producing a water-based alloy is Fe-Cr-CO
In the permanent magnet alloy material 11, powder made of the magnet alloy material is mixed or kneaded with a binder and then injection molded into a mold shown in FIG. The mold shown in FIG. 2 has cavities 4 each around the sprue 1a.
It has a structure in which several pipe-shaped runners 2a are concentrically connected and arranged. In particular, in the present invention, the width (B) or inner diameter (d) of the gate 3a connected to the runner 2a and having a rectangular or circular cross section is set to 4M (5/1 of D>) of the runner 2a.
It is set to be greater than or equal to 00 and less than 1i2.

This limitation is based on the following reasons.

The width (B) or inner diameter (d) of the gate 3a is the same as that of the runner 2.
If it is less than 5/100 of the inner diameter (D) of a, the melted and kneaded material containing the alloy powder will not flow smoothly within the runner 2a and will not flow into the cavity 4a, while on the other hand, the inner diameter (D) of runner 2a may be 1/2 This is because if it exceeds the limit, cutting will not be possible properly at the interface between the molded body filled in the gate 3a and the molded body in the cavity 4a that will become a product.

Then, the injection-molded molded body is debounded. The binder is composed of an organic compound and is removed by separation or volatilization in one binder removal step. The binder-removed molded body is sintered in a vacuum, subjected to a sinter welding treatment, then heat treated in a magnetic field, and then subjected to a continuous aging treatment.

The Fe-Cr-Co magnet alloy powder used in the present invention preferably has the following composition.

0r17-45%, CO3-35% in weight ratio.

The remainder has a composition consisting essentially of Fe, and this is due to the following reason. First, if the Cr content is less than 17%, it is difficult to obtain a coercive force, and if it exceeds 45%, the workability is poor and the residual magnetic flux density is reduced. Next, if the CO content is less than 3%, the coercive force decreases, and if it exceeds 35%, the residual magnetic flux density decreases significantly. In addition, in the present invention, in addition to Or and CO, improvements in magnetic properties (7) (Ti, Nt),
All, V, M.

One or more of W and W may be added. However, even if the amount of these elements added is too large, it will adversely affect the magnetic properties, so it is preferably in the range of 0.01 to 5%. As other additives, elements that have a deoxidizing effect such as C and 3i can also be used, but from the viewpoint of magnetic properties, it is preferably 0.3 to 3% or less.

Hereinafter, the present invention will be explained in detail with reference to Examples.

-6- Example ff1ffi ratio: C010.0%, Cr 25.5%.

s+ 0.4%, r+o, 1%, MOo, 2%.

Blending ratio of alloy powder of 100 mesh or less consisting of A, Q, 0.1%, 80.1% and binder consisting of 1-IDPE, APP (high molecular weight) and APP (low molecular weight) Powder: HDPE: APP (Polymer@):AP
The mixture was heated and mixed at a ratio of P (low molecular weight) = 98:5:9:3, and the inner diameter of the gate connected to the runner around the sprue was set to 3/100 to 3/4 of the inner diameter of the runner. A cylindrical molded product with an outer diameter of 20 nvφ and a thickness of 10 mm was produced using a scrico inline type injection molding machine equipped with a mold in which four runners were connected concentrically.

Degreasing was then carried out at a temperature increase rate of 3°C/hr from 140°C. At this time, the gate/runner ratio suitable for injection molding was 5/100 to 1/2.

Then, in vacuum at 1100℃ x 30min + 1300℃
Sintering was performed for x2 hours. The degree of vacuum at this time is 10=
torr8! It was below 30 degrees. The purpose of maintaining the temperature at 1100°C x -7-3Qmin is to promote the reaction of the binder, which is thought to remain in a very small amount in the powder, with the 02 in the C powder. After sintering, solution treatment was performed at 1100°C for 1 hour, followed by heat treatment at 640°C x 1 hr in 4000 (00) hot water, and then at 615°C x 1 h.
After holding r, cooled at 100°C/24 hr for 50
Continuous aging treatment was performed down to 0°C.

The magnetic properties carried out are Br = 12KGXHc = 51
0 (Oe), (B H) rn = 4, 8 M G
Oe and the sintered density is 7.32<] /CCl20
The dimensional accuracy for the number of samples was ±0.02 mm or less, and the defective rate was 0%.

As is clear from the above examples, Fe according to the present invention
The method for producing a -Cr-Co permanent magnet alloy has the effect of significantly reducing the unpolarization rate because the dredging becomes uniform.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an injection mold used in the conventional WA manufacturing method of Fe Cr-Co based permanent magnet alloy;
FIG. 2 is a schematic sectional view of an injection mold used in an embodiment of the present invention. 1a... Sprue, 2a... Runner, 3a...
Gate. Patent applicant Hitachi Metals Co., Ltd.-9- Figure 1

Claims (1)

[Claims] After mixing or kneading powder made of a Fe-Cr-Co permanent magnet alloy material with a binder, the mixture is provided around a sprue by concentrically connecting a plurality of runners and connected to the runners. The width or inner diameter of the gate is between 5/100 and 1/100 of the inner diameter of the runner. llI! of a Fe-Cr-Co-based permanent magnet alloy, which is injection molded in a mold set at /2, and then sequentially subjected to debinding and sintering. I-building method.