JPH0386354A - Method for drying ceramic shell mold for lost wax casting - Google Patents

Abstract

PURPOSE:To forcedly dry a ceramic shell mold in a short time while preventing excess cooling preceding to de-wax by alternately executing vacuum operation and warm blasting operation under atmospheric pressure. CONSTITUTION:The ceramic shell mold is charged into a drying chamber 11 under condition of opening a sliding door 11b with an air cylinder 11a. After drying this by alternately executing the vacuum operation and the warm blasting operation by the suitable times, this is taken out of the drying chamber 11 under the condition of opening the sliding door 11b. Then, it is desirable that the inner part of the drying chamber 11 is made to reduced pressure condition of <=about 10Torr at the initial stage of drying with the vacuum operation and successively, made to further higher vacuum degree. It is desirable that the temp. in the drying chamber 11 is made to >=30 deg.C with the warm blasting operation preceding to the initial vacuum operation. Further, it is desirable that at least five times or more of either one side of the vacuum operation or the warm blasting operation are executed.

Description

[Detailed Description of the Invention] +l) Purpose of the Invention [Industrial Application Field] The present invention relates to a method for drying a ceramic shell mold for lost wax casting, and in particular, to a method for drying a ceramic shell mold for lost wax casting, and in particular, a method for drying a ceramic shell mold for lost wax casting by vacuum operation while housed in a drying chamber together with a wax model. The present invention relates to a method for drying a ceramic shell mold for lost wax casting, in which the ceramic shell mold is forcibly dried prior to dewaxing by alternately performing hot air blowing operations under atmospheric pressure.

[Prior Art] Conventionally, as a drying method for this type of ceramic shell mold for lost wax casting, the surrounding environment of the ceramic shell mold is reduced by reducing the pressure in the drying chamber in which the ceramic shell mold is housed together with the fil wax model using a vacuum evacuation system. The water vapor evaporated from the ceramic shell mold is removed from the ceramic shell mold by a vacuum evacuation system in order to forcibly reduce the partial pressure of water vapor in the surrounding environment of the ceramic shell mold, and at the same time suppress the increase in the partial pressure of water vapor in the surrounding environment of the ceramic shell mold. removed from the surrounding environment, and further (iii)
The water vapor evaporated from the ceramic shell mold and removed from the drying chamber by the vacuum exhaust system is condensed in a condenser, thereby promoting the evaporation of water and forcibly drying the ceramic shell mold prior to dewaxing. was proposed.

[Problem to be Solved 1] However, in the conventional method of drying a ceramic shell mold for lost wax casting, the drying chamber in which the ceramic shell mold is housed is reduced in pressure by vacuum operation, thereby drying the ceramic shell mold. Since it merely reduced the partial pressure of water vapor in the surrounding environment, it had the disadvantage that (i) the water contained in the ceramic shell mold evaporated rapidly, and (ii) the ceramic shell mold and wax model The disadvantage is that the temperature becomes low, and (iii) excessive stress is generated due to the difference in coefficient of thermal expansion between the ceramic shell mold and the wax model, causing cracking or peeling of the ceramic shell mold. , also fiv
l There is a drawback that the ceramic shell mold reaches a critical moisture content and drying hardly progresses, and in addition, when the ceramic shell mold is taken out from the M drying chamber, condensation forms on its surface and moisture is reabsorbed. Furthermore, when the temperature inside the drying chamber is relatively low, the surface of the ceramic shell mold freezes or condenses, inhibiting the evaporation of water.

Therefore, in order to eliminate these drawbacks, the present invention prevents excessive cooling of the ceramic shell mold and wax model due to vacuum operation by alternately performing vacuum operation and hot air blowing operation under atmospheric pressure. It is an object of the present invention to provide a method for drying a ceramic shell mold for lost wax casting, which comprises forcibly drying the ceramic shell mold in a short period of time prior to dewaxing.

(2) Structure of the Invention [Means for Solving the Problems] The means for solving the problems provided by the present invention is as follows. In a method of drying a ceramic shell mold for lost wax casting, which involves drying the ceramic shell mold prior to dewaxing by lowering the partial pressure of water vapor in the surrounding environment, and (a hot air blowing operation for blowing dry hot air under atmospheric pressure into a BL drying chamber) alternately.''

[Function] The method for drying a ceramic shell mold for lost wax casting according to the present invention is to reduce the pressure in the drying chamber in which the ceramic shell mold is housed together with the wax model by vacuum operation, and to reduce the partial pressure of water vapor in the environment surrounding the ceramic shell mold. A method for drying a ceramic shell mold for lost wax casting, the method comprising drying the ceramic shell mold prior to dewaxing by reducing the fal
It is characterized by alternately performing a vacuum operation to reduce the pressure inside the drying chamber and a warm air blowing operation to blow hot air (drying under atmospheric pressure into the BL drying chamber). It acts to ensure rapid evaporation of moisture contained in the ceramic shell mold, and also acts to prevent the ceramic shell mold and wax model from being excessively cooled due to evaporation of moisture, As a result, (iii) stress is generated between the ceramic shell mold and the wax model due to the difference in coefficient of thermal expansion, which suppresses the ceramic shell mold from cracking or peeling, and the ceramic shell mold reaches a critical water content. In addition, it prevents the temperature inside the M drying chamber from becoming low, and prevents the surface of the ceramic shell mold from freezing or condensing, which inhibits the evaporation of moisture. As a result, the ceramic shell mold is forcibly dried in a short period of time.

[Example] Next, the method for drying a ceramic shell mold for lost wax casting according to the present invention will be specifically described by citing preferred examples thereof. However, the examples described below are described to facilitate or accelerate understanding of the present invention, and are not described to limit the present invention. In other words, each element disclosed in the embodiments described below includes all design changes and equivalent substitutions as long as they fall within the spirit and technical scope of the present invention.

M8 of 55,·× FIG. 1 shows the first method of drying a ceramic shell mold for lost wax casting according to the present invention. FIG. 3 is a perspective view schematically showing a drying device for carrying out a second embodiment.

FIG. 2 is a flowchart showing a first experimental example of a drying method for a ceramic shell mold for lost wax casting according to the present invention, and corresponds to the first example.

FIG. 3 is a graph diagram for explaining the effect of the experimental example shown in FIG.

FIG. 4 is a flowchart showing the second experimental example, and corresponds to the first example.

FIG. 5 is a flowchart showing the third experimental example, and corresponds to the first example.

FIG. 6 is a flowchart showing the fourth experimental example, and corresponds to the second example.

FIG. 7 fal (bl is a flowchart diagram for showing the fifth experimental example, and corresponds to the first example.

FIG. 8 is a flowchart showing an example of the comparative experiment.

First, the structure and operation of the first embodiment of the method for drying a ceramic shell mold for lost wax casting according to the present invention will be explained in detail.

The method of drying a ceramic shell mold for lost wax casting according to the present invention is to reduce the pressure in a drying chamber containing a wax model and the ceramic shell mold by vacuum operation, thereby reducing the partial pressure of water vapor in the environment surrounding the ceramic shell mold. A method of drying a ceramic shell mold for lost wax casting, which comprises drying the ceramic shell mold prior to dewaxing by reducing the
A vacuum operation for bringing the inside of the drying chamber into a reduced pressure state (that is, a vacuum state; the same applies hereinafter) and a hot air blowing operation for blowing dry hot air into the drying chamber at atmospheric pressure are performed alternately.

The vacuum operation is performed to force a reduction in the partial pressure of water vapor in the environment surrounding the ceramic shell mold and to facilitate evaporation of the water contained in the ceramic shell mold. Here, the inside of the drying chamber can be kept at lθ~20 Torr or more during the initial stage of drying by vacuum operation, since the drying time can be moderately shortened by avoiding an increase in the size of the vacuum equipment while avoiding any negative effects on the ceramic shell mold in the early stage of drying. It is preferable to reduce the pressure to a desired reduced pressure state, and then (that is, after a predetermined period of time has elapsed from the start of drying) to reduce the pressure to a higher degree of vacuum. Equipment for performing vacuum operations (
In other words, as the vacuum device), a rotary pump is preferable because a high vacuum state can be achieved. In addition, the vacuum capacity (i.e., decompression capacity) of the vacuum device may be determined by the water retention state of the ceramic shell mold, but it is possible to
It is preferable to have the ability to reduce the pressure to a level of about orr since this will ensure work efficiency.

The hot air blowing operation avoids excessive cooling of the ceramic shell mold and wax model due to vacuum operation, and also prevents the surface of the ceramic shell mold from freezing or condensation due to water vapor in the drying chamber, which prevents moisture from evaporating. At the same time, when the ceramic shell mold is taken out from the drying chamber into the atmosphere, it is in a cooled state, so condensation occurs due to water vapor in the atmosphere, which reabsorbs moisture and inhibits drying. In order to avoid this and thereby ensure rapid evaporation of the moisture contained in the ceramic shell mold and to maintain the ceramic shell mold in its dry state once dried, this is carried out. Here, since the ceramic shell mold and wax model are prevented from being excessively cooled by the hot air blowing operation, excessive stress due to the difference in thermal expansion coefficient is generated between the ceramic shell mold and the wax model. This prevents the ceramic shell mold from cracking or peeling.
Further, it is possible to avoid the ceramic shell mold from reaching a critical moisture content and inhibiting the progress of drying. The interior of the drying chamber is heated by a hot air blowing operation prior to inserting the ceramic shell mold.
If the temperature is 30° C. or higher, the temperature inside the drying chamber will not drop too much during vacuum operation, which is preferable.

The reason why the vacuum operation and hot air blowing operation are performed alternately is to dry the ceramic shell mold in a short time while avoiding excessive cooling of the ceramic shell mold and wax model due to the vacuum operation. It's about forcing.

Here, since the vacuum operation and the hot air blowing operation can sufficiently dry the ceramic shell mold, it is preferable that either one is performed five or more times. In addition, since vacuum operation can prevent the surface of the ceramic shell mold from freezing or condensation due to water vapor in the drying chamber, it can be replaced with hot air blowing operation as soon as the temperature inside the drying chamber does not drop below 16℃. It is preferable that

2.Furthermore, the structure and operation of the second embodiment of the method for drying a ceramic shell mold for lost wax casting according to the present invention will be described in detail.

The second embodiment differs from the first embodiment except that it comprises an initial drying step for air drying the ceramic shell mold in the atmosphere prior to performing the vacuum operation and hot air blowing operation.
It has the same structure and operation as the embodiment.

Therefore, the second embodiment can shorten the drying time compared to the first embodiment.

In addition, with reference to FIG. 1, the first part of the method for drying a ceramic shell mold for lost wax casting according to the present invention will be described.
The structure and operation of the drying device for carrying out the second embodiment will be briefly explained.

(2) is the first method of drying a ceramic shell mold for lost wax casting according to the present invention. A drying apparatus for carrying out the second embodiment, comprising a drying chamber (i.e. vacuum chamber) 1) for accommodating a ceramic shell mold (not shown) and a communication pipe 12a for the drying chamber 1). A hot air blowing device 12 for supplying hot dry air at an appropriate temperature (for example, 80° C.) through the drying chamber 1) is connected to the drying chamber 1) through a communication pipe 13a, and is supplied from the drying chamber 1). A condenser 13 for condensing and removing water vapor from the air is connected to the condenser 13 via a communication pipe 14a, and after sucking air from the drying chamber 1) through the condenser 13, a discharge pipe is provided. a vacuum pump for removal to the outside via 14b (
For example, a hydraulic rotary pump) 14 is provided.

Although not shown, the drying chamber 1) is provided with means for detecting the atmospheric pressure and temperature inside the drying chamber 1).

The ceramic shell mold is inserted into the drying chamber 1) with the sliding door 1)b opened by the air cylinder lla, and is dried by alternately performing vacuum operation and warm air blowing operation an appropriate number of times. Drying chamber 1) with slide fillb opened again by air cylinder lla
taken from.

Lastly, with reference to FIGS. 2 to 8, the first method of drying a ceramic shell mold for lost wax casting according to the present invention will be described. The second example will be described in detail using a specific experimental example.

A ceramic shell mold that has been thoroughly dried in advance,
It was used as a sample piece. The sample piece was weighed prior to the experiment and had a weight of: 1) 97 g (Step 1 in Figure 2); In addition, the temperature of the sample piece and the temperature of the place where the experiment was performed (foundry; hereinafter the same) were both 16°C.
Met.

The sample piece was first immersed for 10 seconds in a colloidal silica solution containing 30% by weight of silica, which is commonly used as a viscosity agent, to fully absorb water (Step 2 in Figure 2). When the sample piece was weighed to determine the amount of water absorbed, the weight increased by 48g, which was 1245g.
(Step 3 in Figure 2).

The sample piece was then inserted and housed in a vacuum chamber serving as a drying chamber (step 4 in Figure 2), where the vacuum chamber employed as a drying chamber was in a state in which no sample piece was yet housed. It had a depressurizing ability that could achieve a depressurized state of about 1 OTorr by vacuum operation for 60 seconds. The temperature inside the drying chamber (ie the vacuum chamber) was 16° C. when the specimen was inserted (see Figure 3).

The drying chamber (i.e. vacuum chamber) is used to vacuum dry the sample pieces after they are accommodated.

The pressure was reduced to 10 Torr by vacuum operation for 3 minutes (Step 5 in Figure 2). The temperature inside the drying chamber was reduced to 15.5°C by this vacuum operation (see Figure 3).

The drying chamber was then blown with dry warm air at atmospheric pressure for 5 minutes with the vacuum operation interrupted to avoid excessive cooling of the sample pieces (step 6 in Figure 2).
), the temperature inside the drying room is reduced to 1 by this hot air blowing operation.
The temperature rose to 7°C (see Figure 3).6 The drying chamber was further equipped with
The vacuum operation for 3 minutes reduced the pressure to 9 Torr (step 7 in Figure 2), and the temperature inside the drying chamber decreased to 16°C (see Figure 3).
.

The drying chamber is again equipped with the following: to avoid excessive cooling of the sample pieces and to avoid condensation on their surfaces due to atmospheric water vapor when removed from the drying chamber.
Vacuum operation was interrupted and dry warm air was blown under atmospheric pressure for 5 minutes (step 8 in Figure 2). The temperature inside the drying room rose to 18℃ due to this hot air blowing operation (
(See Figure 3).

In order to observe the progress of drying, the vacuum operation and hot air blowing operation were interrupted, and the sample piece was taken out into the atmosphere from the drying chamber and weighed, and it was found to have a weight of 1230 g (Figure 2). Step 9゜10). Therefore, the drying rate (i.e. dehydration rate; hereinafter the same) of the sample piece at this time is:
It was 45% (see Figure 3).

The sample piece was again inserted and housed in the vacuum chamber functioning as a drying chamber in order to continue vacuum drying (step 1 in FIG. 2)).

After the sample pieces were housed in the drying chamber, a vacuum operation was performed for 2 minutes to reduce the pressure to 8 Torr in order to vacuum dry the sample pieces (step 12 in FIG. 2). The temperature inside the drying chamber was reduced to 15°C by this vacuum operation (see Figure 3).

The drying chamber was then blown with dry hot air under atmospheric pressure for 5 minutes with the vacuum operation interrupted to avoid excessive cooling of the sample pieces (step 1 in Figure 2).
3). The temperature inside the drying room is controlled by this warm air blowing operation.
The temperature rose to 19°C (see Figure 3).

The drying chamber further includes:
The pressure was reduced to 8 Torr by vacuum operation for 2 minutes (step 14 in FIG. 2). The temperature inside the drying chamber was reduced to 16° C. by this vacuum operation (see Figure 3).

The drying chamber is again equipped with the following: to avoid excessive cooling of the sample pieces and to avoid condensation on their surfaces due to atmospheric water vapor when removed from the drying chamber.
Vacuum operation was interrupted and dry warm air was blown under atmospheric pressure for 5 minutes (step 15 in Figure 2). The temperature inside the drying chamber rose to 19°C due to this hot air blowing operation (see Figure 3).

The sample piece was taken out of the drying chamber and weighed in order to observe the degree of drying achieved by the drying method of the present invention, and found to have a weight of 1221 g (
Step 16.17 in Figure 2). Therefore, the final drying rate of the sample piece at this time was 71% (third
(see figure).

Two ceramic shell molds that had been thoroughly dried by air drying in advance were used as sample pieces A and B.

Sample pieces A and B were weighed prior to the experiment and had a weight of 1) 94 g and 1) 39 g, respectively (step 1 in Figure 4). Moreover, the temperature of the sample piece and the temperature of the place where the experiment was performed were both 16°C.

First, sample pieces A and B are 3, which is commonly used as a viscosity agent.
By being immersed in a colloidal silica solution containing 0% by weight of silica, water was sufficiently absorbed (Step 2 in FIG. 4). When sample pieces A and B were weighed to determine the amount of water absorbed, they had increased in weight by 28 g and 31 g, respectively, and had a weight of 1222 g and 1) 70 g (Step 3 in Figure 4).

Sample pieces A and B were then inserted and housed in a vacuum chamber functioning as a drying chamber (step 4 in Figure 4).
Here, the vacuum chamber employed as the drying chamber had a decompression capacity capable of achieving a reduced pressure state of approximately 10 Torr by vacuum operation for 60 seconds without sample pieces A and B being accommodated yet.

The temperature inside the vacuum chamber was 35° C. when the sample pieces A and B were inserted, since warm air was blown in by a hot air blowing operation prior to the insertion of the sample pieces A and B.

After sample pieces A and B are stored in the drying chamber, sample pieces A and B are stored in the drying chamber.
1 by vacuum operation for 5 minutes to vacuum dry B.
The pressure was reduced to 0 Torr (step 5 in Figure 4).
. The temperature inside the drying chamber was lowered to 24° C. by this vacuum operation.

Thereafter, in order to avoid excessive cooling of specimens A and B, the vacuum operation was interrupted and dry hot air was blown into the drying chamber under atmospheric pressure for 5 minutes (Fig. 4). step 6). The temperature inside the drying chamber rose to 29° C. by this hot air blowing operation.

In the drying chamber, in order to continue vacuum drying of sample pieces A and B,
The vacuum operation for 5 minutes reduced the pressure to 10 Torr (step 7 in FIG. 4), and the temperature inside the drying chamber decreased to 25° C. by this vacuum operation.

Thereafter, in order to avoid excessive cooling of specimens A and B, the vacuum operation was interrupted and dry hot air was blown into the drying chamber under atmospheric pressure for 5 minutes (Fig. 4). step 8). The jB degree in the drying chamber rose to 30°C by this hot air blowing operation.

In the drying chamber, in order to continue vacuum drying of sample pieces A and B,
The pressure was reduced to 9 Torr by vacuum operation for 5 minutes (step 9 in FIG. 4). The temperature inside the drying chamber was reduced to 25° C. by this vacuum operation.

The drying chamber is again equipped with vacuum operation to avoid excessive cooling of specimens A and B and to avoid condensation on their surfaces due to water vapor in the atmosphere when they are removed from the drying chamber. The process was interrupted and dry hot air was blown under atmospheric pressure for 5 minutes (Step 10 in Figure 4). The temperature inside the drying chamber rose to 30° C. by this hot air blowing operation.

In order to observe the degree of drying progress, sample pieces A and B were taken out of the drying chamber into the atmosphere after interrupting the vacuum operation and hot air blowing operation and weighed. (Step 1 in Figure 4). 12). Therefore, sample pieces A and B at this time
The drying rates were 87% and 92%, respectively.

Sample pieces A and B were again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (fourth
Step 13 in the figure).

After sample pieces A and B are stored in the drying chamber, sample pieces A and B are stored in the drying chamber.
8 by vacuum operation for 2 minutes to vacuum dry B.
The pressure was reduced to Torr (step 14 in Figure 4).
).

Thereafter, in order to avoid excessive cooling of specimens A and B, the vacuum operation was interrupted and dry hot air was blown into the drying chamber under atmospheric pressure for 5 minutes (Fig. 4). step 15).

In the drying chamber, in order to continue vacuum drying of sample pieces A and H,
The pressure was reduced to 8 Torr by vacuum operation for 2 minutes (step 16 in FIG. 4).

The drying chamber is again equipped with a vacuum operation to avoid excessive cooling of specimens A and B and to avoid condensation on their surfaces due to atmospheric water vapor when removed from the drying chamber. The process was interrupted and dry hot air was blown under atmospheric pressure for 5 minutes (Step 17 in Figure 4).

In order to observe the progress of drying achieved by the drying method according to the present invention, sample pieces A and B were taken out from the drying chamber into the atmosphere and weighed, each weighing 1200 g.
and 1) had a weight of 43 g (step 18.19 in Figure 4). Therefore, the drying rates of sample pieces A and B at this time were 1) 2% and 124%, respectively. there were.

A ceramic shell mold that had been thoroughly dried in a microwave oven was used as a sample piece. The sample piece is
When weighed prior to the experiment, 1) it had a weight of 74 g (step 1 in Figure 5), and the temperature of the sample piece and the temperature at the location where the experiment was performed were both 18°C; In addition, the relative humidity at the location where the experiment was performed was 3
It was 0%.

The sample piece was first immersed in water to fully absorb water (Step 2 in Figure 5). The sample piece is
When it was weighed to determine the amount of water absorbed, it was found to have increased in weight by 49 g, and had a weight of 1223 g (Step 3 in Figure 5).

The sample piece was then inserted and housed in a vacuum chamber functioning as a drying chamber (step 4 in Figure 5), where the vacuum chamber employed as a drying chamber was in a state in which no sample piece was yet housed. 1 by vacuum operation for 60 seconds
It had the ability to reduce pressure to about 0 Torr.

After the sample pieces were placed in the drying chamber, dry hot air at 80°C was blown under atmospheric pressure for 1 minute to ensure the temperature of the sample pieces (see step 5 in Figure 5) prior to vacuum operation. 5).

The drying chamber is then equipped with three
The pressure was reduced to about 10 Torr by vacuum operation for 0 minutes (step 6 in FIG. 5).

When the sample piece was taken out into the atmosphere from the drying chamber and weighed in order to observe the degree of drying progress, it had a weight of 1202 g, and had a wet appearance as a whole and had been cooled (No. 5). In step 7.8) of the figure, the drying rate of the sample piece at this time was 43%.

The sample piece was again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (step 9 in Figure 5).

After the sample pieces were housed in the drying chamber, dry warm air at 80°C was blown under atmospheric pressure for 5 minutes prior to vacuum operation to ensure the temperature of the sample pieces (step 13 in Figure 5). ).

The drying chamber was then brought to a reduced pressure of approximately 10 Torr by vacuum operation for 10 minutes to continue vacuum drying of the sample pieces (step 1 in Figure 5).

When the sample piece was taken out from the drying chamber into the atmosphere and weighed in order to observe the degree of drying progress, it was found that: 1) it weighed 95 g, had a wet appearance, and had cooled down (No. 5); Step 12.13 in the figure).

The drying rate of the sample piece at this time was 57%.

The sample piece was again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (step 14 in Figure 5).

After the sample pieces were placed in the drying chamber, dry warm air at 80°C was blown under atmospheric pressure for 5 minutes to ensure the temperature of the sample pieces (see step 5 in Figure 5) prior to vacuum operation. 15).

Thereafter, the drying chamber is used to dry the sample piece under vacuum.
The pressure was reduced to about 10 Torr by vacuum operation for 0 minutes (step 16 in FIG. 5).

In order to observe the progress of drying, the sample piece was taken out from the drying chamber into the atmosphere and weighed.1) It had a weight of 90g, had a fairly dry appearance, and had cooled down. Steps 17 and 18 in Figure 5). The drying rate of the sample piece at this time was 67%.

The sample piece was again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (step 19 in Figure 5).

After the sample pieces were placed in the drying chamber, dry warm air at 80°C was blown under atmospheric pressure for 5 minutes to ensure the temperature of the sample pieces (see step 5 in Figure 5) prior to vacuum operation. 20).

Thereafter, the drying chamber is used to dry the sample piece under vacuum.
The pressure was reduced to about 10 Torr by vacuum operation for 0 minutes (step 21 in FIG. 5).

In order to observe the progress of drying, the sample piece was taken out from the drying chamber into the atmosphere and weighed.1) It had a weight of 84 g and had a slightly dried appearance. The specimen was not cooled (step 22 in Figure 5).
．． 23) The drying rate of the sample piece at this time was 80%.

The sample piece was again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (step 24 in Figure 5).

After the sample pieces were placed in the drying chamber, dry warm air at 80°C was blown under atmospheric pressure for 5 minutes to ensure the temperature of the sample pieces (see step 5 in Figure 5) prior to vacuum operation. 25).

Thereafter, the drying chamber is used to dry the sample piece under vacuum.
The pressure was reduced to about 10 Torr by vacuum operation for 0 minutes (step 26 in FIG. 5).

In order to observe the degree of drying progress, the sample piece was taken out from the drying chamber into the atmosphere and weighed.1) It weighed 80 g and had a slightly dried appearance. The specimen was not cooled (step 27 in Figure 5).
．． 28) The drying rate of the sample piece at this time was 88%.

The sample piece was again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (step 29 in Figure 5).

After the sample pieces were placed in the drying chamber, dry warm air at 80°C was blown under atmospheric pressure for 5 minutes to ensure the temperature of the sample pieces (see step 5 in Figure 5) prior to vacuum operation. 30).

Thereafter, the drying chamber is used to dry the sample piece under vacuum.
The vacuum operation was performed for 0 minutes to reduce the pressure to about 10 Torr (step 31 in FIG. 5).

In order to observe the progress of drying, the sample piece was taken out from the drying chamber into the atmosphere and weighed. 1) It had a weight of 76 g and had a slightly dried appearance. The specimen was not cooled (step 32 in Figure 5).
．． 33), the drying rate of the sample piece at this time was 96%.

The sample pieces were dried again under vacuum for several consecutive cycles.

It was inserted into a vacuum chamber that served as a drying chamber (step 34 in Figure 5).

After the sample pieces were placed in the drying chamber, dry warm air at 80°C was blown under atmospheric pressure for 5 minutes to ensure the temperature of the sample pieces (see step 5 in Figure 5) prior to vacuum operation. 35).

The drying chamber is then equipped with 1
The pressure was reduced to about 10 Torr by vacuum operation for 0 minutes (step 36 in FIG. 5).

Sample pieces are used to observe the degree of drying progress.

It was taken out from the drying room into the atmosphere and weighed.

1) It weighed 75g and had a completely dried appearance. The sample piece was not cooled (5th
Steps 37 and 38 in the figure). The final drying rate of the sample piece at this time was approximately 100%.

Narrow Back Example 1 A ceramic shell mold that had been sufficiently dried in advance in a microwave oven was used as a sample piece. The sample piece is
When weighed prior to the experiment, it was found that: 1) it weighed 74 g (Step 1 in Figure 6);

The sample piece was first immersed in water to sufficiently absorb water (Step 2 in Figure 6). When the sample piece was weighed to determine the amount of water absorbed, it was found that the weight had increased by 44 g, and it had a weight of 1218 g (No. 6
Step 3 in the diagram).

The specimens were then air dried in air for 24 hours (step 4 in Figure 6). The sample piece was weighed: 1) It had a weight of 97 g, and its drying rate was 48
% (Step 5 in Figure 6), and the temperature of the sample piece at this time was 19°C (Step 6 in Figure 6).
).

The sample piece was further inserted and housed in a vacuum chamber functioning as a drying chamber (step 7 in Figure 6).

After the sample pieces were placed in the drying chamber, dry hot air at 80°C was blown under atmospheric pressure for 5 minutes before vacuum operation to ensure the temperature of the sample pieces (see step 6 in Figure 6). 8). The temperature of the sample piece (and therefore the temperature inside the drying chamber) is
By this hot air blowing operation, the temperature rose to 25℃ (6th
Step 9 in the diagram).

Thereafter, the drying chamber is used to dry the sample piece under vacuum.
The pressure was reduced to 10 Torr by vacuum operation for 0 minutes (step 10 in FIG. 6). The temperature of the sample piece was lowered to 16°C by this vacuum operation (step 1 in Figure 6).

In order to maintain the temperature of the sample pieces, hot dry air at 80° C. was blown into the drying chamber under atmospheric pressure for 5 minutes prior to vacuum operation (step 12 in FIG. 6).

The temperature of the sample piece rose to 23° C. by this hot air blowing operation (step 13 in FIG. 6).

The drying chamber was then brought to a reduced pressure of 10 Torr by vacuum operation for 10 minutes to continue vacuum drying of the sample pieces (step 14 in Figure 6). The temperature of the sample piece was reduced to 16°C by this vacuum operation (step 15 in Figure 6).

In order to maintain the temperature of the sample pieces, hot dry air at 80° C. was blown into the drying chamber under atmospheric pressure for 5 minutes prior to vacuum operation (step 16 in FIG. 6).

The temperature of the sample piece rose to 23° C. by this hot air blowing operation (step 17 in FIG. 6).

The drying chamber was then brought to a reduced pressure of 10 Torr by vacuum operation for 10 minutes to continue vacuum drying of the sample pieces (step 18 in Figure 6). The temperature of the sample piece was reduced to 17°C by this vacuum operation (step 19 in Figure 6).

In order to maintain the temperature of the sample pieces, hot dry air at 80° C. was blown into the drying chamber under atmospheric pressure for 5 minutes prior to vacuum operation (step 20 in FIG. 6).

The temperature of the sample piece rose to 22° C. by this hot air blowing operation (step 21 in FIG. 6).

The sample piece was removed from the drying chamber into the atmosphere and weighed: 1) It had a weight of 75 g (step 22.23 in Figure 6). Therefore, the drying rate of the sample piece at this time was 96%.

The sample piece was again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (step 24 in Figure 6).

After the sample piece is stored in the drying chamber, the sample piece is heated to 10 Torr by vacuum operation for 10 minutes in order to vacuum dry the sample piece.
The temperature of the sample piece, which was brought into a reduced pressure state of r (step 25 in FIG. 6), was reduced to 17° C. by this vacuum operation (step 26 in FIG. 6).

The drying chamber was then heated at 80° C. under atmospheric pressure for 5 minutes to ensure the temperature of the specimen and to avoid condensation on its surface due to atmospheric water vapor when removed from the drying chamber. dry warm air was blown in (step 27 in Figure 6). The temperature of the sample piece rose to 22°C by this hot air blowing operation (step 28 in Figure 6).
.

The sample piece was removed from the drying chamber into the atmosphere and weighed: 1) It had a weight of 76 g (step 29.30 in Figure 6). The final drying rate of the sample piece at this time was 96%.

Ceramic shell molds that had been sufficiently dried in advance in a microwave oven were used as sample pieces A and B. When sample pieces A and B were weighed prior to the experiment, they each weighed 1
) 73 g and 1096 g (Fig. 7 fat (step l in bl)
It was ℃. Additionally, the relative humidity where the experiment was performed was 20%.

Sample pieces A and B were first immersed in water for 30 seconds to fully absorb water (Fig. 7 (at (
bl step 2). When sample pieces A and B were weighed to determine the amount of water absorbed, they were 1) 4 g and 128 g, respectively.
The weight has increased by 1287 g and 12 g.
It had a weight of 24 g (step 3 in Figure 7 fa) (b)).

The sample pieces A and B were then inserted and housed in a vacuum chamber functioning as a drying chamber (see Figure 7).
step 4). The temperature inside the vacuum chamber was measured to be 12° C. prior to the vacuum operation and hot air blowing operation. Here, the vacuum chamber employed as the drying chamber had a depressurization ability that could achieve a reduced pressure state of about 10 Torr by vacuum operation for 60 seconds without sample pieces A and B being accommodated yet.

After sample pieces A and B are stored in the drying chamber, sample piece A
To ensure the temperature of , B, dry hot air at 80 °C was blown under atmospheric pressure for 60 minutes prior to vacuum operation (
Step 5 in FIGS. 7(a) and (b)).

In order to observe the degree of drying progress, sample pieces A and B were taken out from the drying chamber into the atmosphere and weighed, and found that they weighed 1212 g and 1) 37 g, respectively (see Figure 7 (al)). bl step 6.7), the drying rates of sample pieces A and B at this time were 66% and 68%, respectively.

Sample pieces A and B were subjected to vacuum drying.

The sample piece A was again inserted into the vacuum chamber functioning as a drying chamber (Fig. 7(a) (step 8 of BL)).
The temperature of B (and thus the temperature inside the drying chamber) was measured to be 18°C prior to vacuum operation (Fig. 7 (at
(Step 9 of bl).

After sample pieces A and B are stored in the drying chamber, sample pieces A and B are stored in the drying chamber.
8 by vacuum operation for 5 minutes to vacuum dry B.
Torr (Fig. 7 fal (bl step 10)). The temperatures of specimens A and B were both lowered to 17°C by this vacuum operation (Fig. 7 fal).
(Step 1 of bl)).

The drying chamber was then heated at atmospheric pressure for 7 minutes to ensure the temperature of specimens A and B.
Dry warm air at 0°C was blown (step 12) in Figure 7fa)tb). The temperature of sample pieces A and B both rose to 18.5° C. by this hot air blowing operation (Step 13 in FIG. 7 (al (bl)).

The drying chamber was further reduced to 8 Torr by vacuum operation for 4 minutes in order to continue the vacuum drying of sample pieces A and H (step 14 in Figure 7). The temperature of B was lowered to 17° C. by this vacuum operation (FIG. 7 (al (bl) step 15).

Sample pieces A and B were taken out from the drying chamber into the atmosphere and weighed in order to observe the degree of drying progress, and were found to have a weight of 1201 g and 1) 24 g, respectively.
In Figure (a) (step 16.17 of BL), the drying rates of sample pieces A and B at this time were 75.5% and 78.2%, respectively.

Sample pieces A and B were again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (No. 7
Figure fat (step 18 of bl). The temperatures of sample pieces A and B were both 19°C when measured prior to the hot air blowing operation (step 19 of Figure 7 fal (bl)).
).

After sample pieces A and B are stored in the drying chamber, sample piece A
, H, dry hot air at 80° C. was blown under atmospheric pressure for 7 minutes prior to vacuum operation (FIG. 7(a) (step 20 in BL)).

The temperatures of sample pieces A and B both rose to 20° C. by this hot air blowing operation (step 21 in FIG. 7 (at (bl)).

Thereafter, the drying chamber was brought to a reduced pressure of 8 Torr by vacuum operation for 5 minutes in order to vacuum dry sample pieces A and B (Fig. 7 (al (bl) step 22). By this vacuum operation, the temperatures of B are both 1
The temperature decreased to 7.5°C (step 23 in Fig. 7 fat (bl)).

In addition, dry hot air at 80°C was blown into the drying chamber under atmospheric pressure for 7 minutes prior to vacuum operation to ensure the temperature of specimens A and B (Figure 7fa) (b). Step 24), the temperature of both sample pieces A and B rose to 21'C by this hot air blowing operation (Fig. 7fal
(Step 25 of bl).

Thereafter, the drying chamber was brought to a reduced pressure of 8 Torr by vacuum operation for 3 minutes in order to vacuum dry sample pieces A and B (step 26 in Fig. 7 fal (bl)).

The temperatures of sample pieces A and B were both lowered to 19° C. by this vacuum operation (step 27 in FIG. 7 (al (bl)).

When sample pieces A and B were taken out from the drying chamber into the atmosphere and weighed to observe the degree of drying progress, they were found to have a weight of 1) 91 g and 1) 13 g, respectively (No. 7
In the figure (step 28.29 of BL), the drying rates of sample pieces A and B at this time were 8463% and 86.8%, respectively.

Sample pieces A and B were again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (No. 7
Figure fat (step 30 of bl). The temperatures of sample pieces A and H were both 20.5° C. when measured prior to the hot air blowing operation (step 31 in Fig. 7 fat (bl)).

After sample pieces A and B are stored in the drying chamber, sample piece A
, B, dry warm air at 80° C. was blown under atmospheric pressure for 5 minutes prior to vacuum operation (step 32 in FIG. 7 (al (bl)).

The temperatures of sample pieces A and B did not change due to this hot air blowing operation, and both remained at 20.5°C (Fig. 7 (al.
(Step 33 of bl).

Thereafter, the drying chamber was brought to a reduced pressure of 8 Torr by vacuum operation for 5 minutes in order to vacuum dry the sample pieces A and B (FIG. 7fa) (Step 34 of BL). Through this vacuum operation, the temperatures of sample pieces A and B both decrease to 1.
The temperature decreased to 9℃ (Figure 7fal (bl step 3).
5).

In addition, the drying chamber was heated at 80°C under atmospheric pressure for 5 minutes prior to vacuum operation to ensure the temperature of specimens A and B.
Dry warm air was blown into the samples (Step 36 in Figure 7 (al (b)). The temperatures of both specimens A and B rose to 21'C (Figure 7 ( al
(Step 37 of bl).

The drying chamber was then brought to a reduced pressure of 8 Torr by vacuum operation for 5 minutes in order to vacuum dry sample pieces A and B (see Figure 7 (al (bl) step 38). By this vacuum operation, the temperatures of B are both 1
The temperature decreased to 8°C (Step 3 in Figure 7 (a) and (b)).
9).

When sample pieces A and B were taken out into the atmosphere from the drying chamber and weighed to observe the degree of drying progress, they were found to have a weight of 1) 83 g and 1) 04 g, respectively.
In Figure (a) (step 40.41 of BL), the drying rates of sample pieces A and B at this time were 92.1% and 93.8%, respectively.

Sample pieces A and B were again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (No. 7
Figure (step 42 of al[bl). The temperatures of sample pieces A and B were both 19°C when measured prior to the hot air blowing operation (see step 43 in Figure 7 (al)).
).

After sample pieces A and B are stored in the drying chamber, sample piece A
, H, dry warm air at 80° C. was blown under atmospheric pressure for 5 minutes prior to vacuum operation (FIG. 7(a) (step 44 in BL)).

The temperatures of sample pieces A and B both rose to 20.5° C. by this hot air blowing operation (step 45 in FIG. 7 (al (bl)).

The drying chamber was then brought to a reduced pressure of 8 Torr by vacuum operation for 5 minutes in order to vacuum dry sample pieces A and B (see Figure 7 (step 46 in al (bl)). By this vacuum operation, the temperatures of B are both 1
The temperature decreased to 8℃ (Figure 7 (al (bl) step 4).
7).

Sample pieces A and B were taken out from the drying chamber into the atmosphere and weighed in order to observe the degree of drying progress, and were found to have a weight of 1) 80 g and 1) 01 g, respectively.
Figure (al) (step 48.49 of BL), the drying rates of sample pieces A and B at this time were 94.8% and 96.1%, respectively.

Sample pieces A and B were again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (No. 7
Figure (al (bl) step 50). The temperatures of sample pieces A and B were both 18.5°C when measured prior to the hot air blowing operation (Figure 7 (al (b) step 51). ).

After sample pieces A and B are stored in the drying chamber, sample piece A
, B, dry warm air at 80° C. was blown under atmospheric pressure for 5 minutes prior to vacuum operation (step 52 in Figure 7 (at (bl)).

The temperatures of sample pieces A and H both rose to 20° C. by this hot air blowing operation (step 53 in FIG. 7 (al (bl)).

The drying chamber was then brought to a reduced pressure of 8 Torr by vacuum operation for 5 minutes in order to vacuum dry sample pieces A and B (Fig. 7(a) (step 54 in BL)). , B are both reduced to 1 by this vacuum operation.
The temperature decreased to 8°C (Fig. 7 (at (bl) step 5).
5).

When sample pieces A and B were taken out into the atmosphere from the drying chamber and weighed, they had a weight of 1) 77 g and 1099 g, respectively (see step 56 in Figure 7 (at (bl)).
57). The drying rates of sample pieces A and B at this time were 97.4% and 97.7%, respectively.

Sample pieces A and B were again inserted into the vacuum chamber functioning as a drying chamber to continue vacuum drying (No. 7
In Step 58 of Figures (a) and (b), the temperatures of sample pieces A and B were both 19°C when measured prior to the hot air blowing operation (Step 59 of Figure 7 (al)).
).

After sample pieces A and B are stored in the drying chamber.

To ensure the temperature of specimens A and B, dry warm air at 80°C was blown under atmospheric pressure for 5 minutes prior to vacuum operation (step 60 in Figure 7 (at (bl)).

The temperature of both sample pieces A and B rose to 20° C. by this hot air blowing operation (step 61 in FIG. 7 fat (b)).

The drying chamber was then brought to a reduced pressure of 8 Torr by vacuum operation for 5 minutes in order to vacuum dry sample pieces A and B (see Figure 7 (step 62 in step 62)). By this vacuum operation, the temperatures of B are both 1
The temperature decreased to 8.5°C (FIG. 7fa) (step 63 in BL).

Sample pieces A and B were taken out from the drying chamber into the atmosphere and weighed in order to observe the degree of drying progress, and found that they weighed 1) 75 g and 1098 g, respectively (Figure 7 (a) (steps 64 and 65 of BL), the drying rates of sample pieces A and B at this time are finally 98.
．． 3% and 98.5%.

A ceramic shell mold that had been thoroughly dried in a microwave oven was used as a sample piece. The sample piece is
It was weighed prior to the experiment and found to have a weight of 1097 g (Step 1 in Figure 8).

The sample piece was first immersed in water to sufficiently absorb water (step 2 in Figure 8). When the sample piece was weighed to determine the amount of water absorbed, the weight increased by 59 g; 1) it had a weight of 56 g (Step 3 in Figure 8);

The sample pieces were then air dried in air for 24 hours (step 4 in Figure 8). When the sample piece was weighed, it had a weight of 1) 29 g (step 5 in Figure 8). Therefore, the drying rate of the sample piece at this time was 5.
It was 0%.

The sample piece was further air-dried for 24 hours in the atmosphere (step 6 of Figure 8).The sample piece was weighed and had a weight of 1) 26 g (step 7 of Figure 8); ), therefore, the drying rate of the sample piece at this time is 57
%Met.

The sample pieces were additionally air-dried for 24 hours in air (step 8 of Figure 8); the sample pieces were weighed and had a weight of 1) 10 g (step 8 of Figure 8); 9), therefore, the drying rate of the sample piece at this time is 8
It was 0%.

The sample pieces were further air-dried for 24 hours in the atmosphere (step IO in Figure 8).

When it was weighed, it had a weight of 1) 01 g (Step U in Figure 8). Therefore, the final drying rate of the sample piece at this time was 94%.

According to the present invention, the ceramic shell mold can be forcibly dried in a short time by alternately performing the vacuum operation and the hot air blowing operation.

At this time, in particular, by performing either the vacuum operation or the hot air blowing operation at least five times, the drying rate of the ceramic shell mold could be sufficiently improved.

Similarly, by setting the temperature inside the drying chamber to 30°C or higher by blowing warm air prior to the first vacuum operation, it is possible to prevent the temperature of the ceramic shell mold from dropping excessively during the vacuum operation. Ta.

Further, by reducing the pressure inside the drying chamber to 10 Torr or more in the early stage of drying, it was possible to prevent cracking or peeling of the ceramic shell mold.

At this time, in particular, the drying rate of the ceramic shell mold could be sufficiently improved by bringing the inside of the drying chamber into a higher reduced pressure state after a certain amount of time had elapsed from the start of drying.

Furthermore, since the temperature inside the drying chamber was maintained at 16°C or higher, it was possible to avoid the ceramic shell mold from reaching its limit moisture content and hindering the drying process, and also prevent the ceramic shell mold from cracking or peeling. did it.

Example 2 - The method for drying a ceramic shell mold for lost wax casting according to the present invention involves reducing the pressure in a drying chamber in which the ceramic shell mold is housed together with a wax model by vacuum operation, and removing water vapor in the environment surrounding the ceramic shell mold. A method for drying a ceramic shell mold for lost wax casting, which comprises drying the ceramic shell mold prior to dewaxing by reducing the partial pressure of
A vacuum operation to reduce the pressure inside the drying chamber and a hot air blowing operation to blow dry warm air into the drying chamber under atmospheric pressure are performed alternately. can ensure rapid evaporation of (
(iii) It is possible to avoid excessive cooling of the ceramic shell mold and wax model due to evaporation of moisture, and (iii) to prevent stress caused by the difference in thermal expansion rate between the ceramic shell mold and the wax model. It is possible to prevent the ceramic shell mold from cracking or peeling, and it is possible to prevent the fivl ceramic shell mold from reaching the critical moisture content and hindering the drying process. It is possible to avoid freezing or condensation on the surface of the ceramic shell mold and inhibiting moisture evaporation, and as a result (
vil ceramic shell mold can be dried in a short time.

(3) Effects of the Invention As is clear from the above description, the method of drying a ceramic shell mold for lost wax casting according to the present invention involves reducing the pressure in the drying chamber in which the ceramic shell mold is housed together with the wax model by vacuum operation, thereby reducing the pressure of the ceramic shell mold. In a method for drying a ceramic shell mold for lost wax casting, which involves drying the ceramic shell mold prior to dewaxing by lowering the partial pressure of water vapor in the surrounding environment of the mold, It is characterized by alternately performing a vacuum operation and a hot air blowing operation for blowing dry hot air under atmospheric pressure into the drying chamber, so that the moisture contained in the fil ceramic shell mold is rapidly removed. It has the effect of ensuring good evaporation, and has the effect of preventing the ceramic shell mold and wax model from being excessively cooled due to evaporation of water, and fiii) the ceramic shell mold. It also has the effect of suppressing cracking or peeling of the ceramic shell mold due to stress caused by the difference in thermal expansion coefficient between the wax model and the wax model (ivl). In addition, it has the effect of preventing the temperature inside the Vl drying chamber from becoming low, and the surface of the ceramic shell mold freezes or condenses, which inhibits moisture evaporation. As a result, the fvil ceramic shell mold can be forcibly dried in a short period of time.

[Brief explanation of drawings]

FIG. 1 shows the first method of drying a ceramic shell mold for lost wax casting according to the present invention. A perspective view schematically showing a drying apparatus for carrying out the second embodiment, and FIG. 2 shows a first experimental example regarding the method for drying a ceramic shell mold for lost wax casting according to the present invention. Figure 3 is a graph diagram for explaining the effects of the experimental example in Figure 2, Figure 4 is a flow chart diagram for showing the second experimental example, and Figure 5 is a graph diagram for explaining the effects of the experimental example in Figure 2. FIG. 6 is a flowchart for showing the fourth experimental example, FIG. 7 is a flowchart for showing the fifth experimental example, and FIG. is a flowchart diagram showing a comparative experimental example.

Claims (6)

[Claims] (1) The ceramic shell mold is dried prior to dewaxing by reducing the pressure in the drying chamber in which the ceramic shell mold is housed together with the wax model by vacuum operation and reducing the partial pressure of water vapor in the environment surrounding the ceramic shell mold. In the method of drying a ceramic shell mold for lost wax casting, the method includes (a) vacuum operation to reduce the pressure inside the drying chamber, and (b) hot air blowing to blow dry hot air under atmospheric pressure into the drying chamber. A method for drying a ceramic shell mold for lost wax casting, characterized by performing the following operations alternately. (2) The inside of the drying chamber is vacuum operated to
A method for drying a ceramic shell mold for lost wax casting according to claim 1, wherein the pressure is reduced to Torr or more, and then the pressure is reduced to an even higher degree of vacuum. (3) The temperature in the drying chamber is set to 30° C. or higher by hot air blowing operation prior to the first vacuum operation, as set forth in claim (1) or (2). Drying method for ceramic shell molds for lost wax casting. (4) The statement of any one of claims (1) to (3), characterized in that either the vacuum operation or the hot air blowing operation is performed at least five times or more. Drying method for ceramic shell molds for lost wax casting. (5) The lost wax according to any one of claims (1) to (4), wherein the temperature inside the drying chamber is maintained at 16° C. or higher even by vacuum operation. Method for drying ceramic shell molds for casting. (6) In addition to the vacuum operation and hot air blowing operation, (c) includes an initial drying step for naturally drying the ceramic shell mold in the atmosphere prior to performing the vacuum operation and hot air blowing operation. Claim No. 1 (1) characterized by
) to (5), the method for drying a ceramic shell mold for lost wax casting according to any one of the above.