JPS61140124A - Manufacture of molded magnet oriented in axial direction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a magnet molded body by a right-angle magnetic field pressing method, and more specifically, by using a combination of a mold and a rubber mold, The present invention relates to a method for manufacturing a cylindrical or columnar magnet molded body oriented in a direction.

Although the present invention is not particularly limited, it is an extremely useful method for producing, for example, rare earth magnets.

[Prior Art] A so-called "perpendicular magnetic field pressing method" in which the direction of an applied magnetic field and the direction of pressure applied by a press are perpendicular to each other is conventionally known. This perpendicular magnetic field pressing method usually yields a magnet molded body with properties that are about 20% better than that of the so-called "parallel magnetic field pressing method" in which the direction of the applied magnetic field and the direction of pressure coincide.

It is possible to obtain an axially oriented cylindrical or columnar magnet molded body by the right-angle magnetic field pressing method. For example, JP-A-58-78409 discloses a method for manufacturing a ring-shaped rare earth magnet, and describes a method for manufacturing a columnar magnet molded body oriented in the axial direction. This is achieved by placing a rectangular cylindrical mold between the left and right balls, incorporating a lower mold with a semicircular groove on the upper surface into the mold, and applying pressure with an upper mold having a semicircular groove on the lower surface. This is a method in which magnet powder filled inside is oriented and molded.

[Problems to be Solved by the Invention] However, as stated in the above publication, it is impossible to form a cylindrical or columnar magnet molded body oriented in the axial direction by the right-angle magnetic field pressing method. there were. In the conventional technology as described above, the press-formed product has a columnar shape but has two convex grooves on the outer circumferential surface corresponding to the gap between the upper mold and the lower mold. be. Therefore, it was unavoidable to grind the outer periphery after molding to create a cylindrical body. Further, when manufacturing a cylindrical body, after the cylindrical body is manufactured as described above, a vertical hole must be formed by drilling along the central axis of the cylindrical body.

Therefore, in order to obtain a cylindrical or cylindrical molded product, complicated machining is essential after molding, which inevitably leads to poor productivity and high costs.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to produce an axially oriented cylindrical or cylindrical magnet molded body without post-processing, which was previously considered impossible using the orthogonal magnetic field pressing method. It is an object of the present invention to provide a method that can be easily manufactured and that can manufacture magnet molded bodies of various shapes at low cost.

[Means for Solving the Problems] The present invention, which can achieve the above-mentioned objects, combines a mold and a rubber mold housed inside the mold in the right-angle magnetic field pressing method. This is a device that is filled with magnetic powder and then molded, and this is exactly what makes it so special. The rubber mold used in the present invention has a cylindrical or columnar hollow part, and has a structure in which the hollow part is filled with magnet powder. The rubber mold filled with magnetic powder is then placed in a mold in a right-angle magnetic field press with the axial direction of its hollow part aligned with the direction of the magnetic field, and is press-formed by an upper mold and a lower mold. Ru. Therefore, the obtained magnetic molded body becomes a cylindrical or columnar body oriented in the axial direction.

If the hollow part formed in the rubber mold is cylindrical or cylindrical, a molded product with an almost perfect annular or circular cross section can be obtained, so machining such as periphery grinding or drilling is not required after molding. There is no need to do so. A sintered magnet having good properties can be obtained by sintering the magnet molded body thus obtained by a conventional method.

As the magnet powder to be used, in addition to rare earth magnet powder, ferrite magnet powder and the like can also be used. Although the present invention has the most remarkable effect when obtaining a cylindrical or cylindrical molded object, it is also possible to easily obtain a prismatic or prismatic molded object by the same method. If the shapes and dimensions of the molded bodies differ, it is sufficient to prepare only the appropriate rubber mold, and one type of mold, upper mold, and lower mold can be used. Furthermore, since the mold does not come into direct contact with the magnet powder, there is no need to use expensive cemented carbide, and the mold may be made of a non-magnetic material such as stainless steel.

[Function] A magnetic field acts on the magnet powder filled in the hollow part of the rubber mold from the outside, and the powder is oriented in the axial direction of the hollow part. If pressure is applied in this state, the rubber mold will be compressed. As is well known, rubber transmits pressure like a fluid under high pressure in a closed space. Therefore, the magnet powder filled in the hollow part of the rubber mold is pressure-molded as a reduced body having a similar shape to the hollow part. This can be considered to be the same as in the case of the hydrostatic press method. Therefore, if the hollow part is made into a cylindrical or cylindrical shape, a molded magnet having a similar shape can be obtained.

Therefore, processes such as surface grinding are completely unnecessary after molding. If necessary, by sintering using a conventional method, a magnet oriented in the axial direction and having good characteristics can be manufactured.

[Example] Hereinafter, the present invention will be explained in more detail based on the drawings. FIG. 1 is an explanatory diagram of the method for manufacturing a molded magnet according to the present invention, and shows an example of molding a cylindrical body.

As is clear from the figure, the present invention uses the right-angle magnetic field pressing method. Coils 14 and 16 are provided on the outer periphery of left and right poles 10 and 12, respectively, which are attached to the press machine.
A square cylindrical mold 1 is formed between these left and right balls 10 and 12.
8 will be installed. A lower mold 20 is installed below the square hole of the mold 18, and an upper mold 22, which is attached to the ram of the press from above, is lowered and fitted into the upper part of the square hole.

A major feature of the present invention is that a rubber mold 24 is housed inside such a mold 18. This rubber mold 24
As clearly shown in the figure, it includes a rubber-shaped body 26 and its lid 28. The rubber mold main body 26 has a rectangular parallelepiped shape, and has a first hole 30 with a large diameter in the center thereof, and a second hole 32 with a small diameter at the bottom of the hole 30. On the other hand, the lid part 28 has a structure in which a circular protrusion 34 is formed on its inner surface to fit into the large-diameter first hole 30, and a small-diameter hole 36 is formed in the center thereof. These small diameter 632.36 have the same diameter,
The shape is such that both ends of the non-magnetic metal rod 38 just fit therein.

These rubber molds 24 and the metal rod 38 located in the center
As a result, a cylindrical hollow portion is formed inside the rubber mold 24. Such a rubber mold 24 is housed in the mold 18 in such a direction that the axial direction of the hollow portion formed therein, that is, the central axis direction of the metal rod 38 coincides with the direction of the magnetic field in the right-angle magnetic field press. .

Manufacture of a magnet molded body using such a right-angle magnetic field press apparatus is performed as follows. First, a metal rod 38 is inserted into the rubber mold body 26 of the rubber mold 24, and the tip thereof is a small diameter second metal rod.
so that it fits within the hole 32. Next, the cylindrical gap formed by the filling is filled with magnet powder 40, such as rare earth cobalt-based magnet powder. Then, the upper end of the large diameter first hole 30 of the rubber mold body 26 is closed with the lid body 28. At this time, the end of the metal rod 38 located at the center will fit into the small diameter hole 36 formed at the center of the lid part 28.

After the magnet powder is filled into the cylindrical space of the rubber mold 24 in this manner, it is housed in the mold 18.

Then, the upper mold 22 is inserted into the mold 18. When the coils 14 and 16 are energized before starting pressurization, the left and right balls 10.
12 is magnetized, and a strong magnetic field is generated in the direction of the central axis of the metal rod within the rubber mold 24.

The magnetic field causes the magnet powder 40 filled inside to be oriented according to the polarity of the ball. With the magnet powder 40 oriented in this manner, the upper mold 22 is pressed down with a pressing force F, and the rubber mold 24 is pressurized.

As mentioned above, rubber transmits pressure like a liquid under high pressure in a closed space, so the magnet molded body taken out from the rubber mold is oriented in the axial direction and placed in the rubber mold, as shown in Figure 3. It becomes a cylindrical body with a similar shape to the aerial part. In this way, a cylindrical magnet molded body 42 oriented in the axial direction can be manufactured. Thereafter, by sintering using a conventional method under conditions appropriate to the magnet material, it is possible to produce a highly efficient sintered magnet that is oriented and molded in a strong magnetic field using a right-angle magnetic field press.

As is clear from the above description, the present invention does not involve direct molding using an upper mold and a lower mold, but a rubber mold is interposed between them. This solves the drawbacks of the prior art, such as the formation of protrusions corresponding to the gaps between the two, and makes it possible to produce a molded magnet having a substantially perfect circular cross section.

Although the preferred embodiments of the present invention have been described in detail above, it goes without saying that the present invention is not limited to such a configuration, and may be modified from time to time. When producing a cylindrical magnet molded body instead of a cylindrical one, the second
A rubber mold with a simple structure without the six 301 holes 36 and the metal rod 3J may be used. Also, from this
Even if the molded product is prismatic, prismatic, cylindrical, or has a complex external or internal shape, it can be molded by simply changing the shape of the rubber mold or the metal rod inserted into the center.
It will be clearly understood that it is possible to obtain a magnetic molded body of a desired shape.

Even if the shape of the space inside the rubber mold is a perfect circle in cross section, the cross section is slightly deviated from the perfect circle, as if it was crushed in the pressure direction by a very small amount (tolerable in reality). It tends to become a body. Therefore, if you want to manufacture a completely cylindrical or cylindrical molded product, as shown in Figure 4, the structure of the rubber mold 44 should be devised to create an elliptical shape with a slightly longer diameter in the pressing direction. It is preferable that the hole 46 is shaped like a hole 46.

The ratio of the major axis to the minor axis varies depending on the dimensions of the mold used, the dimensions of the rubber mold, the material of the rubber mold, the properties of the magnet powder filled inside, etc., but it is relatively easy to determine experimentally. be.

In addition, in the above description, the magnet molded body is sintered after being molded, but the present invention is not necessarily limited to sintering. Depending on the magnet powder material used, it is also possible to use it as an unsintered compact like a bonded magnet. Therefore, it is completely free to decide whether or not to sinter after molding.

[Effects of the Invention] Since the present invention is a method for manufacturing a magnet molded body configured as described above, it is possible to produce a cylindrical or cylindrical shaped body oriented in the axial direction, which has conventionally been considered impossible to manufacture only by magnetic field pressing. This has an extremely excellent effect in that a molded magnet can be easily molded without any post-processing.

As a result, it is possible to manufacture products with excellent magnetic properties because the right-angle magnetic field pressing method is used, and since there is no need for post-processing such as grinding or drilling after molding, it is easy to manufacture. It is possible to reduce the cost.

In addition, in the present invention, since the mold does not come into direct contact with the magnet powder, there is no need to use expensive carbide materials, and inexpensive non-magnetic materials such as stainless steel can be used. Since it is carried out using a rubber mold, it is extremely inexpensive even when producing a small amount of molded objects, and the combined effect of all of these can have the excellent effect of significantly reducing costs and improving performance. It is something.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of a right-angle magnetic field press device used in the present invention, Fig. 2 is an exploded perspective view of a mold and a rubber mold used therein, and Fig. 3 is an explanatory diagram showing an example of a right-angle magnetic field press device used in the present invention. FIG. 4 is a perspective view showing an example of a molded magnet, and an explanatory view showing another embodiment of a rubber mold suitable for use in the present invention. 10.12...Pole, 14,16...Coil, 1
8... Mold, 20... Lower mold, 22... Upper mold, 24
... Rubber mold, 26 ... Rubber mold body, 28 ... Lid, 38 ... Metal rod, 40 ... Magnet powder. Patent applicant Fuji Electrochemical Co., Ltd. Agent Shigeru Estimate Figure 1 Figure 3 Figure 4 12Q-

Claims (1)

[Claims] 1. A rubber mold having a cylindrical or columnar hollow part and filled with magnetic powder is housed in a mold in a right-angle magnetic field press so that the axial direction of the hollow part coincides with the direction of the magnetic field. A method for producing an axially oriented magnet molded body, characterized in that the molded body is molded by pressurizing the rubber mold.