JPH03193299A - Molding method and molding device for brittle material - Google Patents

Abstract

PURPOSE:To allow accurate molding without generating cracks in a peripheral part in press molding of a brittle material by pressurizing the side face of the work, which is pressed by means of upper and lower molds, by molten glass. CONSTITUTION:A sintered body 1 is placed on the lower mold 2 and glass powder which is a pressure medium is packed in a container. The glass powder is heated to a prescribed temp. and is melted by a high-frequency heating coil 9. The upper mold 3 is slidably supported and a cap 10 which supports the other end of bellows 6 mounted to the upper mold 3 is mounted to the container 11. The air in the container is discharged. The temp. is uniformized after hermetic closing and thereafter the sintered body 1 is upset while the prescribed pressure is applied to a high-boiling oil 5, such as silicone oil. The bellows 6 compresses the molten glass mentioned above to apply a compressive stress on the side face of the sintered body 1 by the prescribed pressure during this time. The solidified glass easily peels and the crack-free molding is obtd. when the molding is rapidly cooled after the end of the molding and the cap 10 is removed. The molding is thus accurately and rapidly produced without generating the cracks in the peripheral part.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of pressing ultra-quenched magnetic materials for use in magnets, etc.
In particular, the present invention relates to a method for molding magnets that suppresses cracks on the outer periphery of molded products that occur during press molding, and an apparatus for manufacturing the same.

[Conventional technology]

In recent years, super-quenched Nd-Fe-B materials, which have been studied as materials for high-performance magnets, need to be subjected to a large plastic deformation of about 70% to become anisotropic.

However, the above-mentioned materials have low ductility even at high temperatures, and have the disadvantage that they tend to crack at the outer periphery during press forming.

In addition, for the production of products where material anisotropy is a problem or dense products that do not contain pores, the processed material can be statically compressed using high pressure gas pressure at high temperatures without using a mold. However, processing technology is attracting attention.

[Invention tries to solve! II! fi) With the above-mentioned conventional free upsetting press forming technology, it is not possible to plastically deform the highly brittle material as described above to a large extent of about 70% without cracking.

In addition, the processing method that statically pressurizes with high pressure gas pressure at high temperature without using a mold requires a long processing time and has low processing accuracy because it does not use a mold. There was a problem that sealing was difficult.

The object of the present invention is to form a brittle material such as the ultra-quenched Nd-Fe-B material with high precision and a large compression ratio without cracking in one peripheral area. An object of the present invention is to provide a molding method and a molding device.

[Means to solve the problem]

In order to achieve the above object, the present invention applies compressive stress by pressurizing the sides of the workpiece to be pressed by the upper and lower molds with the molten glass. The glass is pressurized by hydrostatic pressure via bellows or by a plunger.

Furthermore, a cooling pipe is provided on the surface of the bellows to control the temperature of the molten glass.

[Effect]

In the press forming method for brittle materials of the present invention configured as described above, the sides of the workpiece to be pressed by the upper and lower molds are pressurized with molten glass to apply compressive stress, thereby preventing the occurrence of cracks in the workpiece. Deter.

〔Example〕 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a hot isostatic press apparatus according to the present invention. The sintered body 1 is placed on a lower mold 1 in a container 11 heated by a high-frequency heating coil 9, and upsetting is performed by an upper mold 3.

Usually, in such upsetting, cracks occur in the periphery of the sintered body. Since this cracking is caused by tensile stress in the peripheral area, this can be suppressed by applying compressive stress to this peripheral area. For this purpose, the container 11 is filled with a pressure medium 4 such as molten borate-based glass or phosphate-based glass, and pressure is applied to this to apply the above-mentioned compressive stress to the peripheral area of the sintered material 1. Do it like this. The pressure is applied by high boiling oil 5 via bellows 6 provided on the surface of the molten glass. Since the pressure medium 4 is sealed inside the container 11 by the bellows 6, it will not leak from the gap between the lid 10 and the upper mold 3 or from other gaps. Further, the surface temperature of the bellows 6 is controlled to a predetermined temperature by a cooling pipe 7. 8 is a pressurizing port for pressurizing the high boiling point oil 5. 9
is a high frequency heating coil for heating the pressure medium 4.

Hereinafter, a specific example of upsetting forming of the Nd-Fe-B magnetic material according to the present invention will be explained.

Figure 2 is a diagram showing the process, in which N d
-F e -B powder is formed into a size of, for example, 19 φ x 201 mm, and then formed into a sintered body 1, followed by hot pressing and upsetting using the apparatus shown in FIG.

First, the sintered body 1 is placed on the lower mold 2, and then the pressure medium 4
It is: 1OI3,0. -10V, O, -602n
The glass powder is filled with glass powder and heated to about 700° C. by the high-frequency heating coil 9 to melt it.Next, the upper mold 3 is supported so as to be slidable, and the bellows 6 attached to the upper mold 3 is heated. A lid 10 supporting the other end is fitted onto the container ll. At this time, the air in the container 11 is completely exhausted. After sealing like this.

After leaving the device at approximately 700℃ for 5 minutes to equalize the temperature, approximately 1000kg/C was applied from the pressurizing port 8! Approximately 70% upsetting is performed by adding high boiling point oil such as silicone oil to the pressure of II.

During this time, the bellows 6 compresses the molten glass due to the pressure, and applies compressive stress to the side surface of the sintered body 1.

After the upsetting molding is completed, the glass is quickly cooled and the lid is removed. Due to the difference in thermal expansion, the glass solidified by cooling is easily separated from the molded product and other parts, resulting in a crack-free shape density as shown in Figure 3. A 20φ×151 molded product with a ratio of 99% or more is obtained. On the other hand, as in the conventional case, the pressure medium 4
If lateral pressure from (molten glass) is not applied, the molded product will crack as shown in Figure 4 due to the tensile stress in the periphery.
2 occurs in large numbers.

Next, an example of forming a square saddle-shaped magnet using the above process of the present invention will be described with reference to FIGS. 5 and 6.

The lower die 21 for the angular saddle shape shown in FIG. An opening 13 is provided on the side surface of the rectangular container 14, and a pressure medium 4, which is molten glass, is introduced into the opening 13.
0P, 20Al□O, A10ZRO glass powder is filled and melted by heating to approximately 710°C with high frequency heating coil 9.Next, in the same manner as in the case of Fig. 1 above, heating is performed for approximately 5 minutes to lower the temperature. After equalizing the pressure, approximately 100
While applying a pressure of 0 kg/aJ to a high boiling point oil 5 such as silicone oil, the upper mold 31 and supporting rod 3 shown in FIG.
2 is lowered to perform upsetting molding. As this upsetting progresses, the molten glass in the rectangular container 14 is pushed out through the opening 13 and acts to keep the pressure around the molded object constant. In this way, the shape is 17.5 x 20 x with an upsetting rate of 70% or more and a density ratio of 99% or more.
A 20h square saddle-shaped magnet could be molded without cracking at the periphery.

Next, another embodiment of the present invention will be described using FIG. 7. In the embodiment of the invention shown in FIG.
Since there are relatively many notarizations, there remains the problem that it takes time to remove the cooled glass after the molding process is completed.

The apparatus shown in FIG. 7 reduces the amount of molten glass 4 and ameliorates the above problem.

In FIG. 7, a pressure cylinder 1 is attached to the bottom of the side of the container 11.
7 is connected, and the molten glass 4 is communicated with the pressure cylinder and pressurized by the plunger 16.

First, the sintered body 1 is placed on the lower mold 2, filled with glass powder as the pressure medium 4, and melted by high-frequency heating, so that the molten glass sufficiently covers the upper part of the sintered body and is sufficiently uniform. The plunger 16 is lowered so that it can be heated. Next, the lid 10 is placed on the lid 10, and after exhausting the air inside the lid 10, the upper mold 3 is lowered to perform upsetting molding. The inside of the lid 1O and the bellows 6 are filled with high boiling point oil 5, and the bellows 6 comes into contact with the molten glass and pushes down the liquid level. It is housed in a pressurizing cylinder 17. At the same time, the pressing force of the plunger 16 is adjusted so that the required pressure is applied to the side surface of the sintered body 1. 18 is a disk made of graphite, and 19 is Grapheye 1~ powder, which has a lower specific gravity than molten glass and prevents molten glass from entering its sliding surface.

As a result of the above operations, the amount of molten glass in the container 11 is reduced in the device shown in Figure 7 compared to the first device, so the number of steps required to remove solidified and peeled glass when taking out the molded product is reduced. The effect of doing so can be obtained.

FIG. 8 is a process diagram of forming a brittle material using the apparatus of the present invention shown in FIGS. 1 and 7 above.

In FIG. 8, first, the heater 9 is heated, the lid 10 and the upper mold 3 are raised, and then the plunger 16 is raised. At this stage, the first sintered body 4 manufactured in the process shown on the right side of the figure is placed on the lower mold 2. The sintered body 1 is made by weighing materials such as Nd, Fe, and B to a predetermined ratio, and then ultra-quenching to form a powder, which is then molded, hot pressed, canned, evacuated, and sealed. generate.

Next, the plunger 16, upper mold 3, etc. are lowered.

Close the lid 10 and apply pressure F to the upper mold 3 in the case of Fig. 1.
A pressure P is applied to the pressurization 8, and in the case of FIG. 7, a force Pp is applied to the plunger 16 in addition to the above F, to form the sintered body 1. After the above molding is completed, the pressure of the above I, P, or F, pp, etc. is released.

Lid 10. After the plunger 16 etc. is raised, the molded product is taken out.

FIG. 9 is a sectional view of another embodiment of the device of the present invention. 9th
In the figure, the bellows 6 in FIG. 1 and FIG.
is omitted, and the molten glass 4 is directly pressurized by the plunger 161. The lower surface of the plunger 161 has an opening in its center that slides through the upper mold 3, and has a donut-like shape that seals between the inner wall of the lid 10 and the upper mold 3. The lower surface of the plunger 161 and the container 11
A graphite plate with graphite powder of a similar shape interposed therebetween is inserted between the liquid surface of the molten glass and the liquid surface of the molten glass. The graphite powder 19 and the graphite plate 181 confine the pressurized molten glass and prevent it from leaking outside the plunger 161.

The pressurizing process of molding is completed, and the molten glass 4 is cooled.

Once solidified, the lid 10 is removed together with the upper mold 3 and plunger 161. At this time, the graphite plate, graphite powder, etc. are lifted by the flange 33 provided at the bottom of the upper mold 3 and removed at the same time. The flange may be provided on the inner circumference of the outer edge of the lid lO.

〔Effect of the invention〕

As described in detail above, when the present invention is applied, it is possible to perform large deformation plastic working of a sintered body, which could not be put to practical use in the past due to the occurrence of cracks. As a result, Nd-lower-e-B magnets, which could not be manufactured using conventional technology, can be manufactured in one piece.
It can be manufactured accurately and quickly without causing cracks in the peripheral area.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a brittle body forming apparatus according to the present invention, and FIG.
The figure is a diagram of the molding process of a brittle body, Figure 3 is a diagram of the shape of a molded body manufactured by the present invention, Figure 4 is a diagram of the shape of a conventional molded body, and Figure 5 (a) is a mold used in the present invention. Perspective view of the lower mold,
FIG. 5(b) is a perspective view of the upper mold used in the present invention;
The figure is a perspective view of a rectangular container accommodating a mold used in the present invention, Figure 7 is a sectional view of another embodiment of the present invention, Figure 8 is a process diagram of the molding process using the apparatus of the present invention, and Figure 9. FIG. 3 is a cross-sectional view of another embodiment of the present invention. 1...Sintered compact, 2.21 etc....lower mold, 3.31 etc....upper mold, 4...pressure medium,
5-...High boiling point oil, 6...Bellows. 7...Cooling pipe. 9... High frequency heating coil, 11... Container, 13... Opening, 16... Plunger, 18... Graphite disc, 32... Rod, 161... Plunger. 8...Pressure port, lO...lid. 12...Cracked, 14...Square container. 17... Pressure cylinder, 19... Graphite powder, 33... Flange. 181...Graph Eye 1-board.

Claims (1)

[Scope of Claims] 1. A method for molding a brittle material, characterized in that in press molding the brittle material, the sides of the workpiece to be pressed by upper and lower molds are pressurized with molten glass. 2. A method for molding a brittle material according to claim 1, characterized in that the molten glass contained in a container is pressurized by hydrostatic pressure via a bellows. 3. In claims 1 and 2, the upper and lower molds and the workpiece are housed in a cylindrical body having an opening, the cylindrical body is housed in the container, and the molten glass is passed through the opening of the cylindrical body. A method for molding a brittle material, characterized in that the workpiece is pressure molded by: 4. A method for forming a brittle material according to claims 1 and 3, characterized in that the workpiece is a sintered body of ultra-quenched Nd-Fe-B powder. 5. A container containing a lower mold of the mold on which the molded product is placed and a container containing the molten glass and equipped with a heating device for the molten glass;
an upper lid that slidably supports the upper mold of the mold and seals the container; Comprising a bellows for enclosing a liquid and a pressurizing port for the liquid,
bringing the bellows into contact with the molten glass surface in the container;
A molding apparatus for a brittle material, characterized in that the molten glass in the container is pressurized by pressurizing the liquid through the pressurizing port. 6. A lower mold of the mold on which the molded product is placed, a container containing the molten glass and equipped with a heating device for the molten glass;
an upper lid that slidably supports the upper mold of the mold and seals the container; The container includes a bellows for sealing a liquid, and the container further includes a cylinder connected to a side surface of the container that accommodates a first plunger, and the first plunger pressurizes the molten glass in the container. Characteristics of molding equipment for brittle materials. 7. The apparatus for molding brittle materials according to claims 5 and 6, characterized in that a cooling pipe is provided on the surface of the bellows. 8. A lower die of the mold on which the molded product is placed, a container containing the molten glass and equipped with a heating device for the molten glass, and an upper lid for sealing the container, further comprising: , a second plunger that slidably supports the upper mold of the mold and slidably seals between the outer edge of the upper lid and the upper mold of the mold; A molding device for brittle materials, characterized in that it pressurizes molten glass. 9. Claims 6 and 8, between the pressure surface of the first plunger and the molten glass surface in the cylinder, or between the pressure surface of the second plunger and the molten glass surface in the container. A molding apparatus for brittle materials, characterized in that at least a graphite plate is provided. 10. The apparatus for molding a brittle material according to claim 9, further comprising a flange provided at a lower part of the upper die of the mold or at a lower part of the inner circumference of the outer edge of the upper lid to prevent the graphite plate from falling.