JP2005046857A - Stainless steel casting manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stainless steel casting manufacturing method capable of considerably shortening the manufacturing time. <P>SOLUTION: In the stainless steel casting manufacturing method, a lost foam pattern 11 with a ceramic base coated on the outer side thereof is heated, the lost foam pattern 11 is evaporated and discharged from the inner side of the ceramic base, the ceramic base is baked to form a ceramic mold 15, molten stainless steel 13 is poured inside the ceramic mold 15, and the ceramic mold 15 is rapidly cooled after maintaining the solid solution temperature for a predetermined time when the temperature of the poured molten stainless steel 13 reaches the predetermined solid solution temperature. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a stainless steel casting, and more particularly, to a method for manufacturing a stainless steel casting that performs a solution treatment.
[0002]
[Prior art]
For example, an austenitic stainless steel casting that requires a solution treatment has a thin water-containing Cr (Fe) oxide passive film formed on the surface by Cr, and has excellent corrosion resistance. Since Cr carbide is formed in the process and a Cr-deficient region may be formed and corrosion resistance is likely to occur, heating to a high temperature and quenching from the solid solution state in which the Cr carbide is melted into the structure of the stainless casting, A solid solution treatment is performed in which the above structure is made into a normal temperature structure as it is (see, for example, Patent Document 1).
[0003]
FIG. 2 shows a process diagram of a conventional method for producing this type of stainless steel casting.
[0004]
As shown in FIG. 2, in the conventional method for producing a stainless steel casting, a mold production process 40 for producing a sand mold 45 from a wooden mold 41, a casting process 50 for casting a stainless steel casting 44 with a molten stainless steel 43, And a solid solution treatment step 60 for performing a solid solution treatment, and the stainless steel casting 44 is manufactured.
[0005]
The mold manufacturing process 40 includes a procedure 40a for manufacturing the wooden mold 41, a procedure 40b for manufacturing one sand mold 45a using the wooden mold 41, and a procedure 40c for manufacturing the other sand mold 45b with the molten metal inlet 46 using the wooden mold 41. And a procedure 40d for manufacturing the sand mold 45 in which the hollow mold portion 41a is formed by the sand molds 45a and 45b.
[0006]
The casting process 50 includes a procedure 50a in which the molten stainless steel 43 is injected into the hollow mold portion 41a from the molten metal inlet 46, and the molten stainless steel 43 is injected into the hollow mold portion 41a. And a procedure 50b in which the stainless casting 44 is cast.
[0007]
The solution treatment step 60 includes a procedure 60a for heating the stainless steel casting 44 to a solution temperature for melting Cr carbide into the structure by the heating furnace 49, and a procedure 60b for keeping the stainless steel casting 44 at the solution temperature for a certain period of time. And a procedure 60c for rapidly cooling the stainless steel casting 44.
[0008]
In the conventional method of manufacturing a stainless steel casting, a sand mold 45 is manufactured from the wooden mold 41 in the mold manufacturing process 40 and the stainless steel casting 44 is manufactured. However, in addition to the wooden mold 41, for example, an extinction model may be used. However, since the conventional disappearance model disappears when the molten metal is injected, there is a possibility that carbon C may remain inside the mold formed outside the disappearance model. Not suitable for manufacturing.
[0009]
[Patent Document 1]
JP 2001-262228 A [Problems to be Solved by the Invention]
However, the conventional method for producing a stainless steel casting has the following problems.
[0010]
A conventional stainless steel casting manufacturing method includes a mold manufacturing process 40 for manufacturing a sand mold 45 from a wooden mold 41, a casting process 50 for casting a stainless steel casting 44 using a molten stainless steel 43, and a solution treatment process 60 for performing a solution treatment. However, in the mold manufacturing process 40, it takes a lot of time to manufacture the wooden mold 41 and the sand mold 45. In the casting process 50, after the molten stainless steel 43 is injected, the heat insulation of the sand is performed. A lot of time is required for cooling for the effect, and in the solution treatment step 60, particularly, a lot of time is required for heating the stainless steel casting 44 to the solution temperature, and a lot of treatment time is required.
[0011]
The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a method for manufacturing a stainless steel casting that greatly reduces the manufacturing time.
[0012]
[Means for Solving the Problems]
The method for producing a stainless casting according to the present invention comprises heating a vanishing model having a ceramic substrate coated on the outside, vaporizing the vanishing model and discharging the ceramic substrate from the inside of the ceramic substrate. A ceramic mold is formed by firing, and a molten stainless steel is injected into the ceramic mold. When the injected molten stainless steel reaches a predetermined solution temperature, the solution temperature is maintained for a certain period of time, and the ceramic mold is maintained. It was decided to cool quickly.
[0013]
In addition, the time from when the molten stainless steel is injected to the predetermined solution temperature is measured in advance, and when the time has elapsed since the molten stainless steel is injected, the predetermined solid solution temperature is reached. I decided to do it.
[0014]
Further, the rapid cooling of the ceramic mold is forced air cooling, forced air cooling mixed with mist, or water cooling.
[0015]
Moreover, the said evanescent model which apply | coated the said ceramic base material to the outer periphery was dried at 60 degrees C or less, and decided to form the said ceramic template by baking at 800-900 degreeC after the said drying.
[0016]
Furthermore, the ceramic substrate contains at least 50% of fused silica.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0018]
FIG. 1 is a process chart of a method for producing a stainless steel casting according to an embodiment of the present invention.
[0019]
As shown in FIG. 1, in the method for manufacturing a stainless steel casting according to the embodiment of the present invention, a mold manufacturing process 10 for manufacturing a ceramic mold 15 using a vanishing model 11 manufactured from a synthetic resin foam material, and a stainless steel 13 using a molten stainless steel 13. A casting production process 10 for casting the casting 14 and performing a solution treatment of the stainless steel casting 14 is performed. The mold manufacturing process 10 in which the stainless casting 14 is manufactured includes expanded polystyrene (EPS), polymethylmeta A procedure 10a for producing the vanishing model 11 from a synthetic resin foam such as acrylate (PMMA) and a co-polymer of the both using an NC processing machine (not shown) and the like, and applying a ceramic substrate on the surface of the vanishing model 11 The procedure 10b for forming the ceramic layer 15a with the molten metal inlet 16 and the disappearance model in which the ceramic layer 15a is formed on the surface 1 is dried at a temperature of about 60 ° C. or lower, put in a heating furnace 19 and heated at a predetermined firing temperature (800 ° C. to 900 ° C.), and the vanishing model 11 is vaporized and discharged by heating and disappears. And a procedure 10c for firing a strong ceramic mold 15 having a hollow mold portion 11a formed therein.
[0020]
Heating in the heating furnace 19 is raised to about 500 ° C. and held at that temperature for about 3 hours. Thereafter, the temperature is increased again to 900 ° C. By maintaining the temperature in the heating furnace 19 at 500 ° C., the vanishing model 11 is vaporized during that time and discharged from the plurality of holes and the molten metal inlet 16 formed in the ceramic mold 15. There is no possibility of carbon C remaining inside.
[0021]
The casting / solid solution treatment step 20 includes a procedure 20a in which the molten stainless steel 13 is injected from the molten metal inlet 16 into the hollow mold part 11a while the ceramic mold 15 is kept at a high temperature by firing, and the hollow mold part 11a. When the temperature of the molten stainless steel 13 injected into the furnace is lowered to the solid solution temperature, the ceramic mold 15 in which the stainless casting 14 is cast by the injection of the molten stainless steel 13 is placed in the heating furnace 19 and kept at the solid solution temperature for a certain time. A procedure 20b for removing the ceramic mold 15 from the heating furnace 19 and quenching, and a procedure 20d for collapsing the ceramic mold 15 and taking out the stainless casting 14 by the rapid cooling of the procedure 20c.
[0022]
The ceramic mold 15 is stressed due to the difference in shrinkage rate from the stainless casting 14 due to the rapid cooling of the procedure 20c, and the ceramic mold 15 collapses. Therefore, the stainless casting 14 can be easily taken out from the ceramic mold 15. By including at least 50% of fused silica, the ceramic base material has a large shrinkage rate when the temperature is lowered, and can be more easily disintegrated.
[0023]
Since the molten stainless steel 13 is injected into the ceramic mold 15 at a high temperature in the procedure 20a, the stainless steel casting 14 from which defects such as shrinkage cavities and gas blows are removed is caused by the directional solidification of the molten stainless steel 13. Can be manufactured.
[0024]
The time required for manufacturing a stainless steel casting will be compared between a conventional manufacturing method of a stainless steel casting and a manufacturing method of a stainless steel casting according to an embodiment of the present invention.
[0025]
1. Conventional stainless steel casting manufacturing method (1) mold manufacturing process 40
Procedure 40a 20-day procedure 40b 1-day procedure 40c Procedure 40b and parallel work procedure 40d 1-day (2) Casting process 50
Procedure 50a 3 days (Large time until the poured stainless steel melt 43 is cooled to room temperature)
Procedure 50b Short time (3) Solution treatment step 60
Procedure 60a 0.5 days (heating stainless steel casting 44 to solution temperature)
Procedure 60b Short time (1-2 hours)
Procedure 60c Short time (4) Total time required About 25.5 days Manufacturing method of stainless steel casting of embodiment of the present invention (1) Mold manufacturing process 10
Procedure 10a 5 days Procedure 10b 2 days (The ceramic substrate coated on the vanishing model 11 is dried at 60 ° C. or lower)
Procedure 10c 0.5 days (2) Casting / Solution Treatment Process 20
Procedure 20a 1 day (requires time to decrease to solution temperature)
Procedure 20b Short time (1-2 hours)
Procedure 20c Short-time procedure 20d Short-time (3) Total time required About 8.5 days In the conventional stainless steel casting manufacturing method, in the mold manufacturing process 40, the mold 41 is manufactured and the sand mold 45 is manufactured and dried. Time is required, and it takes a lot of time to cool the poured molten stainless steel 43 to room temperature in the casting process 50, and much time is required to heat the stainless steel casting 44 to the solid solution temperature in the solution treatment process 60. Need a lot of energy.
[0026]
In the method of manufacturing a stainless steel casting according to the embodiment of the present invention, the processing time can be shortened by manufacturing the ceramic mold 15 in the mold manufacturing process 10, and the stainless steel mold 15 is coated with stainless steel in the casting / solution treatment process 20. By injecting the molten metal 13 and lowering the solution temperature to a solid solution temperature, the treatment time can be shortened by carrying out a solid solution treatment that maintains the solid solution temperature, and the treatment time can be reduced to less than half of the conventional stainless steel casting manufacturing method. be able to.
[0027]
As described above, the method for manufacturing a stainless steel casting according to the embodiment of the present invention performs the solution treatment in which the molten stainless steel 13 is injected into the ceramic mold 15 and the solution temperature is maintained when the temperature is lowered to the solution temperature. As a result, the manufacturing time can be greatly shortened.
[0028]
In the above description, the stainless steel has been described as an example. However, the method for producing a stainless steel casting according to the present invention can be applied to materials that do not contain carbon and other low carbon alloy steels.
[0029]
Further, in the method for producing a stainless steel casting according to the present invention, the time from when the molten stainless steel is poured to the predetermined solution temperature is measured in advance, and when the measurement time has elapsed since the molten stainless steel was poured. Alternatively, it may be when a predetermined solution temperature is reached.
[0030]
【The invention's effect】
The method for producing a stainless casting according to the present invention comprises heating a vanishing model having a ceramic substrate coated on the outside, vaporizing the vanishing model and discharging the ceramic substrate from the inside of the ceramic substrate. A ceramic mold is formed by firing, and a molten stainless steel is injected into the ceramic mold. When the injected molten stainless steel reaches a predetermined solution temperature, the solution temperature is maintained for a certain period of time, and the ceramic mold is maintained. Therefore, the manufacturing time can be greatly reduced by injecting a molten stainless steel into the ceramic mold and performing a solution treatment that maintains the solution temperature when the temperature is lowered to the solution temperature.
[0031]
In addition, the time from when the molten stainless steel is injected to the predetermined solution temperature is measured in advance, and when the time has elapsed since the molten stainless steel is injected, the predetermined solid solution temperature is reached. Therefore, it is possible to easily detect that a predetermined solution temperature has been reached without directly measuring the temperature of the injected molten stainless steel.
[0032]
Moreover, since the rapid cooling of the ceramic mold is forced air cooling, forced air cooling with mist mixing or water cooling, accurate forced air cooling can be performed according to the size and shape of the ceramic mold.
[0033]
In addition, since the vanishable model having the ceramic base material coated on the outer periphery is dried at 60 ° C. or less, and fired at 800 to 900 ° C. after the drying, the ceramic mold is formed. Manufacturing time can be shortened.
[0034]
Further, since the ceramic base material contains at least 50% of fused silica, when the temperature of the ceramic mold formed by the ceramic base material is lowered, the shrinkage rate becomes large and collapses. It can be taken out.
[Brief description of the drawings]
FIG. 1 is a process chart of a method for producing a stainless steel casting according to an embodiment of the present invention.
FIG. 2 is a process diagram of a conventional method for producing a stainless steel casting.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Mold manufacturing process 11 Dissipative model 11a Hollow mold part 13 Stainless steel melt 14 Stainless steel casting 15 Ceramic mold 15a Ceramic layer 16 Molten metal inlet 19 Heating furnace 20 Casting / solid solution treatment process

Claims (5)

Heating the extinction model coated with a ceramic substrate on the outside, vaporizing the extinction model and discharging from the inside of the ceramic substrate, firing the ceramic substrate to form a ceramic mold, A stainless casting in which a molten stainless steel is injected into a ceramic mold, and when the injected molten stainless steel reaches a predetermined solid solution temperature, the solid solution temperature is maintained for a predetermined time, and the ceramic mold is rapidly cooled. Manufacturing method. The time from when the molten stainless steel is injected until the predetermined solution temperature is reached is measured in advance, and when the time has elapsed since the molten stainless steel is injected when the predetermined solid solution temperature is reached The method for producing a stainless steel casting according to claim 1, wherein: The method for producing a stainless casting according to claim 1, wherein the rapid cooling of the ceramic mold is forced air cooling, forced air cooling mixed with mist, or water cooling. 2. The ceramic mold is formed according to claim 1, wherein the vanishing model in which the ceramic base material is coated on an outer periphery is dried at 60 ° C. or less, and fired at 800 to 900 ° C. after the drying to form the ceramic mold. Stainless steel casting manufacturing method. The method for producing a stainless casting according to claim 1, wherein the ceramic substrate contains at least 50% of fused silica.

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