JPS58155909A - Method of molding slurry - 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 This invention relates to a method of forming a slurry containing a material, in particular a method of filling a slurry of an oxide permanent magnet material into a mold and having dehydration holes.
The present invention relates to a method of forming a slurry by passing it through a filter member through a filter, dehydrating it under pressure in a magnetic field, and forming the slurry.

Conventionally, when pressurizing and dehydrating a slurry of oxide permanent magnet material filled in a mold, the particle size of the magnetic powder that makes up the slurry is about 0.8 to 1.2 μm, so dehydration is extremely difficult. Unfortunately, the pressure in the mold increases during pressurized dewatering during molding, which causes slurry to leak from the space between the die and the centimeter, the gap between the sliding parts, the IE wrench play, the slurry case, etc. This causes backflow.

In addition, even if there is a slight leak in the molded product that is difficult to detect, the product obtained by firing has the disadvantage of causing partial peeling or cracking, so it is necessary to prevent slurry leakage. In order to do this, there is a drawback that the molding speed must be slowed down.

The present invention eliminates these drawbacks and provides a slurry molding method that eliminates slurry leakage and improves molding efficiency by heating the slurry during pressure dehydration molding. Its purpose is to

A feature of the present invention is that when molding a slurry containing ceramic material or bamboo oxide permanent magnet material by removing liquid,
The slurry was transferred to room temperature tool f-. It is a method of forming slurry that is heated using υ.

Generally, the filtration rate in variable pressure dehydration is expressed by the following formula.

υ: Filtration rate μ: Viscosity of the dispersion medium P: Effective dehydration pressure: Constant - L As is clear from the equation, in order to increase the filtration rate υ (improve the dehydration properties of the slurry), it is necessary to increase the The purpose is to reduce the viscosity μ, and for this purpose, it is sufficient to heat the slurry.

Embodiments of the present invention will be described below based on the drawings.

Here, FIG. 1 is a curve diagram showing the relationship between the solid content residual rate and the slurry temperature when the slurry is subjected to pressure dehydration molding under constant molding conditions.

In the figure, A indicates an average particle size of 0. A slurry with a water concentration of 40% made of magnetic particles of micrometer diameter was prepared using a 40 mm tube with dehydration holes in the groove.
1002 is charged into a φ mold, and the initial speed is 0.4w/sec.
And B has an initial velocity of 0.8 van/sec,
These are characteristic curves showing the relationship between solid content residual rate and slurry temperature when pressure dehydration is carried out at a shoulder pressure of 0.34 t/' in a magnetic field.

In curves A and B, a solid content residual rate of 100% means that there was no slurry leakage; slow pressurization speeds reduce slurry leakage, and higher slurry temperatures significantly reduce slurry leakage. It can be seen that the solid residual rate is increasing.

As curve A shows, the initial velocity is 0411II at room temperature 20°C.
The residual rate of i/511c when dehydrated under pressure is 90%, and as curve B shows, the solid content residual rate can be reduced even if the pressurization rate is approximately twice as high by heating the slurry temperature to 55°C. It is clear that the dewatering properties of the slurry are improved since the residual rate is 90% and remains at the same level.

This is because a filtration layer is quickly formed on the sliding parts of the mold where slurry tends to leak and on the dewatering surface of the filtration vortex member during the initial pressurization period when the pressure inside the mold is low, and this plays the role of a seal. When the pressurization progresses further and the pressure inside the mold becomes high, the high pressure inside the mold is reduced due to the high temperature of the slurry, and filtration proceeds without destroying the filtration layer of the filtration vortex member that has been formed, and the slurry By preventing leakage. Note that it is desirable to heat the slurry immediately before pressure molding in terms of thermal efficiency.

Figure 2 shows a non-thermal slurry with a pulverized particle size of 0.73 μm,
It is a curve diagram showing the relationship between the compression speed of the heated slurry and the slurry pressure inside the mold according to one example.

In the same figure, C is a curve showing a non-thermal slurry, and D is a curve showing a heated slurry.As is clear from the comparison of the curve and C, the heated slurry has a higher compression speed than the non-thermal slurry. The slurry pressure inside the mold will not increase even if the mold is heated, and no slurry leakage will occur.

As explained above, the slurry forming method according to the example can prevent slurry leakage during pressurized dewatering by heating the slurry, and can prevent partial peeling and cracking of products caused by slurry leakage. In addition, it is possible to improve molding efficiency by reducing the pressurization speed.

As described above, the present invention can provide a method for molding a slurry containing a ceramic material or an oxide permanent magnet material, which can eliminate slurry leakage and improve molding efficiency. Therefore, it can be said that the invention has excellent practical effects.

[Brief explanation of the drawing]

Figure 1 is a curve diagram showing the relationship between solid content residual rate and slurry temperature when slurry is pressurized and dehydrated under constant molding conditions, and Figure 2 is a curve diagram showing the relationship between compression speed and slurry pressure inside the mold. It is a curve diagram showing a relationship.゛、-ノ

Claims (1)

[Claims] When removing liquid from a slurry containing a ceramic material or an oxide permanent magnet material and forming the slurry, the slurry is heated to a temperature above room temperature.
A slurry forming method characterized by heating to a high temperature.