JP3028702B2 - Method of making lost wax mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a defect-free lost wax mold without deteriorating a slurry.

[0002]

2. Description of the Related Art Generally, in order to prepare a lost wax mold, a normal wax pattern is immersed in a gypsum or phosphate slurry, pulled up, and dried to form a gypsum or phosphate around the wax pattern. Forming a coating layer, drying and solidifying this coating layer,
Further, it is well known that a wax pattern is produced by melting and discharging the same.

When the above wax pattern is immersed in a slurry of gypsum or phosphate, the wax pattern entrains bubbles, and the bubbles adhere to the pattern surface, or bubbles existing in the slurry adhere to the pattern surface. This may cause defects in the mold.

In order to prevent this, a method has been proposed in which a wax pattern is immersed in a slurry under reduced pressure or in a vacuum atmosphere (see Japanese Patent Application Laid-Open No. Sho 62-214849).

[0005]

However, when the slurry is placed in a reduced pressure or vacuum atmosphere, the water in the slurry evaporates and the optimal composition balance is lost, and the slurry itself is partially gelled to deteriorate the slurry. There was a problem. To solve this problem, it is conceivable to replenish the slurry with water. However, it is difficult to accurately grasp the amount of water to be replenished, and the balance of the optimum composition tends to be lost.

Further, it takes a long time for the replenished water to be well mixed in the slurry. Further, once the water content is reduced, the slurry gels. Therefore, the water must be replenished in a very short cycle. Extremely bad.

[0007]

Means for Solving the Problems Accordingly, the present inventors have
As a result of researching to develop a method of preventing the slurry from deteriorating even if the wax pattern is immersed in the slurry in a reduced pressure or vacuum atmosphere and having no adverse effect on workability, (1) reduced pressure or The partial pressure of water vapor in a vacuum atmosphere depends on the temperature, so that water may be supplied from another system using steam. (2) As a specific means for this, a water refill tank is installed in a reduced pressure or vacuum atmosphere. The temperature of the slurry is 0.5 to 20 ° C
If filled with high-temperature water and left as it is, a reduced pressure or a partial pressure of water vapor in a vacuum atmosphere can be kept constant, and evaporation of the water in the slurry is prevented, so that the slurry does not deteriorate. (3) In this case, when the temperature difference between the temperature of the water filled in the water refill tank and the temperature of the slurry is 0 ° C., the evaporation of the water content of the slurry cannot be prevented, while the water temperature of the water refill tank exceeds 20 ° C. higher than the slurry temperature. Then, the difference between the water vapor pressure in the vacuum or vacuum atmosphere and the water vapor pressure of the slurry exceeds 44 Torr, the water content of the slurry increases, the optimum composition is lost, and the defoaming effect in the slurry by the pressure reduction or vacuum also decreases. They found that it was not desirable.

The present invention has been made based on this finding, and a wax pattern is immersed in a slurry in a reduced-pressure or vacuum atmosphere and pulled up to form a slurry coating layer around the wax pattern. In the method of manufacturing a lost wax mold by heating and melting and discharging a wax pattern after drying and solidifying a coating layer, the method may be such that the above-mentioned reduced pressure or the steam pressure in a vacuum atmosphere is maintained so as to be higher by 1 to 44 Torr than the steam pressure of the slurry. Or 0.5 above the slurry temperature
The method is characterized by a method for producing a lost wax mold in which water maintained at a temperature higher by about 20 ° C. is put into a water refill tank and placed in the above-described reduced pressure or vacuum atmosphere.

The method for producing the lost wax mold will be described in more detail with reference to the drawings.

FIG. 1 is an explanatory view of a process for producing a lost wax mold. 1 is a defoaming coating device, 2 is a slurry, 3 is a lost wax pattern, 4 is a hanging rod, 5 is a water refill tank, and 6 is a coating layer. , 7 are air bubbles.

[0011] As shown in FIG.
Into the defoaming coating device 1 and the wax pattern 3
Is set on the hanging bar 4. Then, as shown in FIG. 1 (b), a rehydration tank 5 containing water 8 was attached to the defoaming coating device 1, and the pressure in the defoaming coating device was reduced by a vacuum pump (not shown). 7 disappears. As shown in FIG. 2, the rehydration tank 5 can maintain the water 8 at a predetermined temperature by a high-resistance heating wire 9.

After keeping the inside of the defoaming coating apparatus 1 at a reduced pressure, the wax pattern 3 is immersed in the slurry 2 as shown in FIG. 1C, and then as shown in FIG. Then, when the wax pattern 3 is pulled up from the slurry 2, the slurry 2
After the coating layer 6 is dried and solidified, the wax pattern 3 is removed by heating and melting to prepare a lost wax mold.

[0013]

EXAMPLES The present invention will be described more specifically based on examples.

[0014] Zircon flower of 200 mesh is 70
3% by weight of colloidal silica containing 30% by weight of SiO ₂
0% by weight and stirred for 24 hours to prepare a slurry. This slurry was kept at room temperature (23 ° C.) and the viscosity was measured. The result was about 30 seconds with Zahn Cup # 5.

This slurry was filled in a defoaming coating apparatus, and the water in the water refill tank was maintained at the temperature shown in Table 1. Then, the atmosphere in the defoaming coating apparatus was changed to 22 to 65.
The coating pressure was reduced to a predetermined pressure in the range of mmHg, the wax pattern was immersed in the slurry under the reduced pressure, and the coating test in which the wax pattern was pulled out of the slurry was continuously and repeatedly performed 100 times. Was measured using a Zahn Cup # 4, and the silica concentration in the slurry was measured by separating the mixture into a liquid and a solid using a centrifugal separator. The presence or absence of defects on the inner surface of the mold and the appearance of the slurry were also observed. The results are shown in Table 1.

[0016]

[Table 1]

From the results shown in Table 1, the difference between the water temperature of the rehydration tank and the temperature of the slurry is 0.5 to 20 ° C., that is, the difference between the steam pressure of the reduced pressure atmosphere and the steam pressure of the slurry is 1 to 44 ° C.
In the methods 1 to 7 of the present invention within the range of Torr, gelation of the slurry was not observed even after the coating test was performed 100 times, but gelation of the slurry was severe in the conventional method in which the water refilling tank was not placed in a reduced pressure atmosphere. It can be seen that the slurry becomes unusable after 100 coating tests.

However, as seen in Comparative Example 1, even if the water refill tank is placed in a reduced pressure atmosphere, the slurry gels unless the water temperature of the water refill tank is higher than the temperature of the slurry.
On the other hand, as shown in Comparative Example 2, when the water temperature of the water refill tank is higher than the slurry temperature by more than 20 ° C. (that is, when the difference in water vapor pressure is higher than 44 Torr), gelation of the slurry is prevented. However, it can be seen that this is not preferable because defects occur on the inner surface of the lost wax mold.

[0019]

As described above, according to the present invention, the slurry can be prevented from deteriorating even if it is used for a long time, and excellent effects such as greatly improved workability and cost can be obtained as compared with the prior art. Is played.

[Brief description of the drawings]

FIG. 1 is an illustration of a method for producing a lost wax mold according to the present invention.

FIG. 2 is an explanatory sectional view of a water refill tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Defoaming coating device 2 Slurry 3 Lost wax pattern 4 Hanging rod 5 Rehydration tank 6 Coating layer 7 Bubbles 8 Water 9 High resistance heating wire

Claims (4)

(57) [Claims] 1. A wax pattern is immersed in a slurry in a reduced pressure or vacuum atmosphere, pulled up to form a coating layer of the slurry around the wax pattern, and after drying and solidifying the coating layer, the wax pattern is heated and melted and discharged. A method for producing a lost wax mold, wherein the steam pressure in the reduced pressure or vacuum atmosphere is maintained higher than the steam pressure of the slurry. 2. The method for producing a lost wax mold according to claim 1, wherein the difference between the water pressure in the reduced pressure or vacuum atmosphere and the water vapor pressure of the slurry is in the range of 1 to 44 Torr. 3. A wax pattern is immersed in the slurry in a reduced pressure or vacuum atmosphere, pulled up to form a coating layer of the slurry around the wax pattern, and after drying and solidifying the coating layer, the wax pattern is heated and melted and discharged. In the method for producing a lost wax mold, by placing water in the water refill tank in the reduced pressure or vacuum atmosphere, and maintaining the water temperature in the water refill tank 0.5 to 20 ° C. higher than the slurry temperature. A method for producing a lost wax mold. 4. The method for producing a lost wax mold according to claim 3, wherein the water refilling tank is adapted to adjust a water temperature.