JPS63219502A - Method for molding sintered head alloy powder - Google Patents

Abstract

PURPOSE:To easily and rapidly mold sintered hard alloy powder to a desired shape by forming split molds from a model of a prescribed shape filling xerogel consisting of the sintered hard alloy powder, thermosetting resin and water into the molds, heating the molds to cure the resin and carrying out sintering. CONSTITUTION:A model of a desired shape formed with wood, plastics or a metal is put in a vessel and gypsum or the like is poured to form a split mold 4 consisting of a cope 41 and a drag 42. Such split molds 4 are set in a prescribed vessel and xerogel or xerosol consisting of sintered hard alloy powder, thermosetting resin and water as starting material 3 is filled into the molds 4 under pressure with a plunger 5. The entire molds 4 are slowly heated to the curing temp. of the resin to cure the resin as well as to evaporate the water. The resulting sintered hard alloy stock having the same shape as the model is subjected to prescribed sintering. Thus, the sintered hard alloy powder is easily molded to any desired shape such as a simple or complex shape in a short time.

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℃~
A method is used in which the material is pre-sintered at a temperature of about 1,000°C to give it a certain degree of strength, and then ground 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 by processing a model of the desired shape out of cemented carbide, as shown in FIG. 1(a), out of wood, plastic, or metal. Next, for example, plastic is poured into this to produce a split mold consisting of an upper mold and a lower mold of the model as shown in FIG. 1(c). 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℃/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 Go powder (average particle size 1.5μ)
．． 0μ) in a wet ball mill so that Go becomes 15% by weight, and then add 2% by weight of thermosetting resin to the dry powder.
and 8% by weight of pure water was added.

The mixture was kneaded in a Henschl mixer to form a xerogel-like state. Model 1 shown in FIG. 1(a) 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, after the hardened implant resin has hardened,
Thin zenyl plate 2 (thickness 0.3cm) so that it can be easily split into
) is attached to the model as shown in Fig. 1(b).A split mold soil consisting of the upper mold 41 and lower mold 42 of the model as shown in Fig. 1(C) is made using hardened potting resin. ,
Six sets of these were set as shown in FIG. 2, and a xerogel-like cemented carbide material 3 was press-fitted with a plunger 5 from the direction of the arrow. In this case, the press-in pressure was 5 kg/d. Note that in FIG. 2, dan is a mold. Mold 6 after press-fitting
was removed, the remaining part was gradually heated to 100° C., and the upper and lower molds were removed to obtain a cemented carbide material having the same shape as Model 1 shown in FIG. 1(a). This material was heated in vacuum at 100°C/min and sintered at 1350°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 granule powder 1
．． 0μ) was mixed in a wet ball mill so that the Co content was 15% by weight, and then 2% by weight of thermosetting resin and 12% by weight of pure water were added to the dry powder, which was kneaded in a Henschel mixer to form a xorosol. I made it to the state of . 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 on X10
One set of split molds with a length of 0n+n+ was prepared, and 5 pieces of xologel-like cemented carbide material similar to that used in Example 1 were added to this set.
It was press-fitted at kg/cd. 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 gradually changed depending on the amount of water evaporated, but it was possible to generate heat and harden under the conditions of 30 A to 100 A and 20 to 50 V. 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 the drawing]

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. Figure 1 (C) is a schematic perspective view showing the split mold produced using this method, 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)

[Scope of Claims] A method for forming cemented carbide comprising the following steps (a) to (e). (a) A model having the same shape as the molded object desired to be obtained as a cemented carbide is processed and formed using wood, plastic, or metal. (b) The model obtained in (a) is placed in a predetermined container, and a hardening resin or plaster is poured into the container to produce a split mold of the model. (c) A cemented carbide material in the form of xorogel or xorosol, which is a mixture of cemented carbide powder, thermosetting resin, and water, is flowed or press-fitted into the split mold obtained in (b). (d) Gradually raise the temperature of the entire split mold to the curing temperature of the resin,
At the same time as the water evaporates, the molded body is cured by the curing action of the thermosetting resin. (e) The hardened compact is sintered according to a normal cemented carbide manufacturing process.