JPS63219501A - Method for molding sintered hard alloy powder - Google Patents

Abstract

PURPOSE:To easily mold sintered hard alloy powder to a prescribed shape in a short time by filling xerogel consisting of the sintered hard alloy powder, water soluble thermosetting resin and water into a mold under pressure and by heating the mold to evaporate the water and to cure the resin. CONSTITUTION:Sintered hard alloy powder consisting of WC and Co or the like is mixed with water soluble thermosetting resin and water and the mixture is kneaded until xerosol or xerogel is prepd. The mixture is poured into a mold of a prescribed shape or filled into the mold under pressure and the entire mold is heated to cure the resin as well as to evaporate the water. Thus, the sintered hard alloy powder can be easily rapidly molded to any desired shape such as a simple or complex shape.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for compacting cemented carbide powder.

[Conventional technology]

In the conventional method for manufacturing cemented carbide, it is common to add paraffin wax or polyethylene wax to powder and mechanically press-form the powder into a predetermined shape. However, after filling the powder into a mold, pressure is applied from above and below, and the product is removed.This method, which is repeated continuously, limits the shapes that can be molded.
If you want to obtain a more complex shape, press the press body at 800℃~
The method used is to perform temporary sintering at a temperature of about 1,000° C. to give it a certain degree of strength, and then grind it with an electrodeposited diamond grindstone. However, with this method, there are unavoidable problems with the time it takes to obtain a complex shape and the yield rate when grinding the powder, and there are limits to the shapes that can be achieved by grinding.

Other methods include extrusion molding and rubber press molding, but these methods have the drawback of being limited to simple shapes. In addition, the slip casting method has disadvantages in that it is not capable of mass production, and the strength of the molded product is weak, making it inconvenient to handle.

In addition, the injection molding method requires time and money to manufacture the mold, and the degreasing process after injection is extremely time consuming.

An object of the present invention is to overcome these conventional problems and provide a molding method that can easily and quickly mold shapes ranging from simple shapes to complex shapes.

[Means for solving problems]

The present invention is an application of slip casting and injection molding in a broad sense, and is characterized by the use of a thermosetting resin and water and by the ease of manufacturing the mold. This will be explained below.

The mold is made of cemented carbide as shown in Figure 1(a) by processing wood, plastic, or metal. ) Make a split mold consisting of an upper mold and a lower mold of the model as shown in the figure. The upper and lower molds are set around the mold as shown in FIG. 2, and the cemented carbide powder in the form of xorosol or xorogel is flowed or press-fitted into the mold, and then the whole is heated to harden.

By the invention of the method described above, it is possible to obtain a molded article extremely easily and quickly.

It is easier to mass produce than slip casting, and because it uses a thermosetting resin and water, the molded product after water evaporation has much greater strength than that simply slip cast. Furthermore, compared to injection molding, the split mold according to the present invention is produced by cutting the unevenness with a metal mold or by electric discharge machining, but it goes without saying that the mold can be manufactured much more easily.

Also, in order to make a sol or gel state using a thermosetting resin and water, it is sufficient to increase the amount of water, and the amount of the resin itself is at most 1
~3% by weight. Therefore, after drying the moisture, it is possible to degrease at a speed of about 100°C/hour.
5-b in normal injection molding It is much more efficient.

〔Example〕

Example 1 Commercially available WC powder (average particle size 1.5μ) and Co powder (average particle size 1.5μ)
．． 0μ) in a wet ball mill so that the Co content is 15% by weight, and then add 2% by weight of thermosetting resin to the dry powder.
and 8% by weight of pure water were added and kneaded in a Henschel mixer to form a xerogel-like state. This is the first (a)
Model 1 shown in the figure was placed in a container, and a commercially available hardened potting resin was poured into the container to create a mold of this model. In this case, a thin Zenyl plate 2 (thickness 0.31) is attached to the model as shown in FIG. 1(b) so that the hardened implant resin can be easily split into two after hardening. As a result of the above, the upper mold 41 and lower mold 42 of the model shown in FIG.
Six sets of split molds were prepared as shown in FIG. 2, and a xerogel-like cemented carbide material 3 was press-fitted with a plunger 5 in the direction of the arrow. In this case, the press-in pressure was 5 kg/-, as shown in FIG. 2 and in the mold. After press-fitting, remove the mold 6 and heat the remaining part to 100℃.
The first mold (
a) A cemented carbide material having the same shape as Model 1 shown in the figure was obtained. This material was heated in vacuum at 100°C/min, and
Sintering was performed at 350°C for 1 hour. No change was observed in the properties of the obtained sintered body compared to the sintered body obtained by wet mixing WC powder and Co powder. The characteristic results are shown in Table 1.

Table 1 Example 2 Commercially available WC powder (average particle size 1.5μ) and Co powder (average particle size 1.5μ)
．． 0 μ) was mixed in a wet bowl so that the Go content was 15% by weight. To the dried powder, 2% by weight of thermosetting resin and 12% by weight of pure water were added, and the mixture was kneaded in a Henschl mixer. It was made into a xorosol state. In the same manner as in Example 1, split molds (upper mold and lower mold) were made using plaster instead of the hardened implant resin, and a xorosol-like carbide material was injected into these molds.

After injection, the temperature was raised to 100°C at a heating rate of 0.5°C/min. After raising the temperature, the plaster was removed to obtain a molded body having the same shape as the model. In this case, the molded product had sufficient strength because it contained a thermosetting resin. A sintered body was produced from this molded body in the same manner as in Example 1. No problems were observed in the properties of the obtained sintered body.

According to the method of the present invention, it takes one day to obtain the sintered body in both Examples 1 and 2, but unlike the conventional method, the powder is pressed, pre-sintered, ground with a diamond grindstone, The method of further sintering took 4 days.

Example 3 In the same method as Example 1, φ10×100+m
One set of split molds of different lengths was prepared, and 5 kg/a of xologel-like cemented carbide material similar to that used in Example 1 was applied to the molds.
It was press-fitted at i. This was placed in a mold with terminals attached to both ends to allow current to flow through it, and heating was performed by passing the current through. In this case, the current value will gradually change depending on the amount of water evaporation, but it will be 30A.
~100A.

It was possible to generate heat and cure under the conditions of 20 to 50V. Therefore, products formed by this method can also be cured by heating with electricity.

〔Effect of the invention〕

According to the present invention, as long as split molds can be manufactured, products with complex shapes can be manufactured in a short period of time and without producing scraps.

[Brief explanation of drawings]

Fig. 1(a) is a model with the same shape as the one desired to be molded as a carbide material, and Fig. 1(b) is a schematic perspective view showing a state in which a thin plastic plate is attached to the model for making a split mold. Fig. 1(c) is a schematic perspective view showing the split mold thus manufactured, in which (a) is the upper mold, (b) is the lower mold, and (
c) shows the combined state, and FIG. 2 is a schematic diagram showing the press-fitted state for molding.

Claims (1)

[Claims] Cemented carbide powder, water-soluble thermosetting resin, and water are mixed and kneaded to form a xorosol or xorogel, which is then flowed or press-fitted into a mold having a predetermined shape, and then the entire mold is heated to remove moisture. A method for molding cemented carbide powder, characterized by curing the resin at the same time as evaporating it to obtain a predetermined shape.