JPH10156522A - Method for removing coating on porous metallic mold for casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove the coating without clogging the coating in pores and crushing the pores on surface layer by executing a water jet blasting treatment having prescribed ranges of water pressure and shifting speed of injection nozzle to a porous metallic mold for casting repeatedly casting by applying the coating and having a prescribed ranges of average pore diameter and poring ratio. SOLUTION: On the porous metallic mold applying the coating, the coating is thinned by repeatedly executing the casting, and the function as the coating is damaged and thus, it comes to be necessary to recoat, but the coating once applied is wholly removed and it is necessary to apply the recoating. As this purpose, to the porous metallic mold for casting, repeatedly executing the casting by applying the coating and having 20-50μm average pore diameter and 20-35% pore ratio, the water jet blasting treatment is executed at 200-800kgf/cm<2> water pressure and 0.25-1.20m/min shifting speed of the injection nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an average pore diameter of 20 to
The present invention relates to a method for removing a coating mold applied to a porous mold for casting having a porosity of 20 to 35% and having pores of 50 μm on the entire surface.

[0002]

2. Description of the Related Art Conventionally, when low-pressure casting or gravity casting of non-ferrous metal such as aluminum is performed by using a mold, gas or air cannot be removed from a cavity. Has been done. However, since it is very troublesome to apply a slit or a vent plug to the mold, recently, a gas-permeable porous mold having fine holes on the entire surface of the mold (for example, JP-A-6-33112). Has been developed and used. As a casting porous mold, one having a pore size of 20 to 50 μm and a porosity of 20 to 35% is usually used. Such a porous mold is manufactured by low pressure casting,
When used for gravity casting, it is common to apply a mold to the cavity for the purpose of preventing surface erosion due to molten metal and keeping the temperature as in the case of the conventional mold.

[0003]

The porous mold coated as described above becomes thinner in the same manner as the conventional mold by repeatedly performing casting, so that the mold becomes thinner. The function is impaired and re-molding is required, but it is necessary to remove all the applied molds and re-mold. For this reason, thinner molds are generally removed with a wire brush or sand blast, but if the mold removal with a wire brush is repeated several times, the mold will become clogged in the vent holes that are ventilated. The pores on the surface are crushed, and the air permeability, which is a feature of the porous mold, is reduced, so that there is a problem that the degassing effect cannot be obtained. The present invention has been made in view of the above problems, and has as its object to provide a method for removing a coating mold without impairing the air permeability of a porous mold for casting.

[0004]

Means for Solving the Problems In order to achieve the above object, the method of removing a coating die of a porous mold for casting according to the present invention is based on an average pore diameter of 2 which is obtained by repeatedly performing casting after applying a coating die.
Water jet processing is performed on a porous mold for casting having a porosity of 0 to 50 μm and a porosity of 20 to 35% at a water pressure of 200 to 800 kgf / cm ² and an injection nozzle moving speed of 0.25 to 1.20 m / min. It is a feature.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The average pore diameter is 30 μm and the porosity is 28
%, A disk-shaped test piece having a diameter of 50 mm ¢ and a height of 5 mm was prepared from a casting mold material having a surface roughness of 3% by electric discharge machining.
Finished to μm. Next, a coating die coat 140ESS (trade name) manufactured by Foseco Japan Limited is applied to one surface of the test piece to a thickness of 50 μm, and then heated at 600 ° C. for 3 hours to completely cure the coating binder. I let it. The test piece obtained in this manner was subjected to various changes in pressure applied to water (containing a rust inhibitor) of a water jet, a moving speed of an injection nozzle, and the like, and an attempt was made to remove a coating mold. Table 1 shows the results of evaluating the coating residue and damage. The test device is a sealed structure with a moving device that operates in orthogonal three dimensions. There is a high-pressure pump unit outside, and a high-pressure washing machine that performs processing by injecting the high-pressure water generated here from a spray nozzle attached to the moving device. And two types of injection nozzles: an eccentrically rotating multi-nozzle of 0.2 mm ¢ × 7 (linear injection type) and a 0.8 mm ¢ flat spray nozzle.

[0006]

[Table 1]

According to Table 1, the water pressure is 200 to 800 kgf / cm.
^2. The moving speed of the injection nozzle 0.25 to 1.20 m / mi
It was confirmed that if the water jet treatment was performed with n, the mold could be removed to the inside of the pores without damaging the surface of the porous mold for casting. Also, when the water pressure was 200 kgf / cm ² or less, the mold could not be formed. It was also found that the surface could not be completely removed, and that the surface was damaged when it was 1000 kgf / cm ² or more. Next, the test piece of the coating application obtained in the same manner as described above was subjected to water jet treatment under the conditions of No. 9 in Table 1, and application of the coating die and removal of the coating die were repeated several times. As a result, if water-jet treatment is applied to the coated porous mold for casting, the mold is not clogged in the pores even if the mold removal is repeated, and the pores in the surface layer can be crushed. Thus, it was confirmed that the coating mold could be removed and the permeability was hardly reduced.

[0008]

As is clear from the above description, the present invention has an average pore diameter of 2 which is obtained by repeatedly performing casting with coating.
Water-jet blasting is performed on a porous mold for casting having a porosity of 0 to 50 μm and a porosity of 20 to 35% at a water pressure of 200 to 800 kgf / cm ² and an injection nozzle moving speed of 0.25 to 1.20 m / min. Therefore, the mold can be removed without substantially crushing the pores in the surface layer while maintaining the initial air permeability.

Claims (1)

[Claims] A water pressure of 200 to 800 kgf / cm ^{2 is} applied to a casting porous mold having an average pore diameter of 20 to 50 μm and a porosity of 20 to 35%.
A method for removing a mold from a porous mold for casting, wherein water jet blasting is performed at an injection nozzle moving speed of 0.25 to 1.20 m / min.