JPH10193032A - Method for removing core sand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fully remove core sand from the inner space of a cast product by dipping the cast product cast by using the core consisting essentially of calcium carbonate into acid solution and dissolving the core sand forming the core. SOLUTION: The cast product is filled with the core for forming the inner space. This core is made of the exoskelton of a pearl oyster, etc., discharged as an industrial waster as the raw material and consisting essentially of the calcium carbonate. This core sand is removed by applying the vibration to the case product or sand blasting, etc., This case product α is dipped into a tank T1 incorporating the acid solution (a) of nitric acid, etc., and the core sand is dissolved into the nitric acid solution and fully removed from the inner space. In the case of the cast product is made of an aluminum alloy, since the nitric acid is the desirable acid because the advance effect is not given to the case product α. Successively, the case product is dipped into a tank T2 filled with cleaning water (b) and washed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing core sand from a casting product cast with a core by effectively removing core sand.

[0002] Conventionally, core sand is synthetic sand obtained by artificially mixing a binder such as Kibushi clay and other substances into a molding sand mainly containing silicic acid (SiO2) such as silica sand, river sand or beach sand. Is used. The core made from such core sand can withstand the molten metal pressure,
Since it is required to be excellent in fire resistance and air permeability, it is usually manufactured by a shell mold method, a cold box method, or the like.

[0003] The core obtained as described above is set in a mold to form an internal space of the casting, and is separated and removed from the casting after casting.

Since the core sand in a casting product is heated at the time of casting, a binder made of a synthetic resin or the like that has bound the core sand particles is easily lost and easily collapsed. Physical removal is performed by applying mechanical vibration or irradiating sand blast.

[0005]

In recent years, however, there has been a problem that core sand has been difficult to remove from cast products due to thinning of the casting. For example, when the core is a shell core, the amount of heat received by the core is reduced due to the thinning of the casting, and the ratio of the unburned synthetic resin of the binder contained in the core is large, and therefore, the collapse of the core is reduced. There is a problem that it is difficult to occur and core sand is difficult to remove from the cast product.

Accordingly, the present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a method for removing core sand from a casting product, which can effectively remove core sand. Is to do.

[0007]

In order to achieve the above object, a method for removing core sand according to the present invention comprises, in an acid solution, a cast product cast using a core containing calcium carbonate as a main component. It is characterized by immersing and dissolving and removing the core sand forming the core. Further, the casting product is made of aluminum, and the core sand is manufactured from a shell.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a process diagram for implementing a method for removing core sand according to one embodiment. Hereinafter, description will be made in the order of steps. (A) Product take-out process When a mold (not shown) is unframed, a cast product B is taken out.
The removed casting product A is filled with a core B for forming an internal space A '. This core is a new core separately proposed by the present applicant, and is used as a shell for oysters, scallops, etc., discharged as industrial waste from a fishery processing plant.
Or they are made from pearl oyster shells, which are discharged as industrial waste from pearl manufacturing plants. That is,
The core is made from shells containing calcium carbonate (CaCO3) as a main component. The method of manufacturing the shells will be described in brief. Organic matter, such as scallops, was incinerated and removed. Next, the shells that have been incinerated are crushed by a crusher.

The pulverized material pulverized by the crusher is separated using a sieve into a known size of foundry sand. The aggregate obtained by sorting as described above, that is, foundry sand, is manufactured as a core having a predetermined strength as a core by a well-known shell molding method, a cold box method, or the like.

[0010] (b) Physical removal step [0010] The inner space b 'of the cast product I is formed in the same manner as the well-known removal of core sand, that is, vibration is applied to the cast product A or sand blasting is performed. It is physically removed by a method or the like.

Although this physical removal step is not an essential step of the present invention, most of the core sand b 'can be removed from the internal space a' by this step, so that the load of the later-described dissolution removal step is reduced. be able to.

(C) Dissolution and removal step A casting product A is immersed in a tank T1 containing a nitric acid solution (HNO3) a. As a result, the core sand B 'is dissolved in the nitric acid solution a and completely removed from the internal space A'. That is, since the core sand B 'remaining in the internal space A' is made of calcium carbonate (CaCO3), it is removed by the following chemical reaction. CaCO3 + 2HNO3 → Ca (NO3) 2 + H2 O +
Instead of CO2 and nitric acid, other acids capable of dissolving CaCO3 such as hydrochloric acid (HCl) can be used. However, the casting A is made of an aluminum alloy (in the present invention, aluminum including aluminum alloy is used). In this case, nitric acid is a preferred acid because it does not adversely affect the cast product (a).

In this melting step, the casting A is completely immersed in the nitric acid solution a. However, the core sand B 'adhering to the casting A is removed from the casting A. The nitric acid solution a may be sprayed (sprayed) into the internal space a ′. Therefore, the term “immersion” in the present invention includes such spraying.

(D) Rinse step The cast product A after the dissolution and removal step is immersed in the tank T2 containing the wash water b and washed with water. In this washing step, the washing water b may be sprayed on the casting A without being immersed in the tank T2.

As described above, the core sand b '
To remove the internal space of the casting
, And the subsequent inconvenience of the cast product a caused by the remaining core sand b 'can be prevented.

[0016]

According to the method for removing core sand according to the present invention, a casting product cast using a core containing calcium carbonate as a main component is immersed in an acid solution to form the core. Since the core sand is dissolved and removed, the core sand can be completely removed, and the subsequent inconvenience of the casting product caused by the remaining core sand can be prevented. In addition, when the cast product is made of aluminum and the core sand is manufactured from shells, the influence of the acid on the cast product can be reduced, and the industrial waste can be effectively used.

[Brief description of the drawings]

FIG. 1 is a process chart for carrying out a method for removing core sand according to an embodiment of the present invention.

[Explanation of symbols]

 A Casting products A 'Internal space B Core b' Core sand T1, T2 tank a Nitric acid solution b Wash water

Claims (2)

[Claims] A casting product cast using a core containing calcium carbonate as a main component is immersed in an acid solution to dissolve and remove the core sand forming the core. Core sand removal method. 2. The method for removing core sand according to claim 1, wherein the cast product is made of aluminum, and the core sand is manufactured from shells.