JPH08229631A - Casting mold for copper alloy - Google Patents

Abstract

PURPOSE: To improve the quality of castings while suppressing the generation of fine powder particularly at the time of reconditioning of a casting mold suitable for making a large-sized copper alloy casting. CONSTITUTION: Sand prepd. by adding an alkali phenol as a binder to granular slag (grain size 0.8 to 1.2mm) obtd. by rapidly cooling electric furnace slag from a molten state is used as backing slag in a backing slag layer 1. Sand prepd. by adding the alkali phenol as the binder to granular aluminum (grain size 0.6 to 0.8mm) is used as facing sand in a facing sand layer 2. As a result, crushing resistance is improved and the generation of the fine powder at the time of reconditioning is lessened; in addition, a reconditioning rate is improved and the finer structures of the copper alloy casting are formed according to an improvement in cooling rate, by which the quality is enhanced and the air permeability is increased and, therefore, the generation of blow hole defects in the casting products is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold suitable for producing a large-sized copper alloy casting.

[0002]

2. Description of the Related Art Conventionally, in the case of producing a large-sized copper alloy casting, a mold material of which silica sand is molded and hardened with water glass or cement has been used.

[0003]

By the way, in the conventional copper alloy mold as described above, since the fine powder of the binder burned during casting and the fine powder of crushed sand are generated during sand regeneration,
There is a problem that it is not preferable in terms of work environment. Further, since the above-mentioned fine powder is discarded in a landfill, it is not preferable from the viewpoint of waste reduction, and a casting material with a low disposal rate is desired.

The present invention is intended to solve the above-mentioned problems, and it is possible to suppress the generation of fine powder as much as possible, while at the same time contributing to the improvement of the quality of casting products. The purpose is to provide.

[0005]

In order to achieve the above-mentioned object, a mold for copper alloy of the present invention is a mold for casting a copper alloy, wherein a skin sand layer and a back sand layer covering the outer surface of the skin sand layer. In addition, the skin sand forming the skin sand layer is made of granular aluminum to which alkali phenol is added as a binder, and the back sand forming the back sand layer is used when refining molten steel in an electric furnace. It is characterized in that it is composed of granular slag produced by rapidly cooling the discharged electric furnace slag from a molten state, to which alkali phenol is added as a binder.

The copper alloy mold of the present invention is characterized in that the grain size of the granular aluminum is 0.6 to 0.8 mm.

Further, the copper alloy mold of the present invention is characterized in that the grain size of the granular slag is 0.8 to 1.2 mm.

[0008]

In the above-described copper alloy mold of the present invention, granular aluminum added with alkaline phenol (binder) is used as skin sand, and alkaline sand is used as back sand in the granular slag obtained by rapid cooling of the electric furnace slag. (Binder) is used, so the crush resistance is improved compared to the conventional case where water glass or cement is included as a binder in silica sand, and the generation of fine powder during regeneration is significantly improved. Will be reduced to.

Further, by using granular aluminum as skin sand, the solidification of the casting and the cooling rate at the time of cooling can be improved, so that the structure of the product is miniaturized,
The mechanical properties are improved, and particularly when the grain size of granular aluminum is set to 0.6 to 0.8 mm, the quality as a copper alloy casting is remarkably improved.

Furthermore, the electric furnace slag used as the back sand is more excellent in crush resistance than silica sand which is a conventional mold aggregate, and has a particle size of 0.8 to 1.2 mm, which is a conventional mold material (silica sand). If the diameter is larger than 0.3-0.8 mm), the air permeability will be larger, so that the gas generated from the mold during pouring and solidification can be removed, which will affect the mechanical properties of casting products. Can be prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A copper alloy mold according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 (a) is a longitudinal sectional view thereof, and FIG. 1 (b) is a transverse sectional view thereof.

The copper alloy mold of this embodiment is used for producing a particularly large copper alloy casting, and as shown in FIGS. 1 and 2, the outer surface of the skin sand layer 2 forming the inner mold 3 is Back sand layer 1
It is covered with. The skin sand forming the skin sand layer 2 is
The back sand, which is made up of granular aluminum with alkali phenol added as a binder, forms the back sand layer 1 by rapidly cooling the electric furnace slag discharged from the molten state when refining molten steel in the electric furnace. It is composed of the granular slag prepared by adding alkali phenol as a binder.

The particle size of the granular aluminum in the skin sand of the skin sand layer 2 is set to 0.6 to 0.8 mm, and the particle size of the granular electric furnace slag in the back sand layer 1 is set to 0.8 to 1.2 mm. In each of the back sand forming the back sand layer 1 and the skin sand forming the skin sand layer 2, the proportion of alkali phenol added as an additive is 1.5 wt%.

In the copper alloy mold of this example, granular aluminum having a particle size of 0.6 to 0.8 mm and alkali phenol as a binder are used for skin sand, and the molten electric furnace slag is rapidly cooled for the back sand. By using a granular slag with a particle size of 0.8 to 1.2 mm and alkali phenol as a binder, the generation of fine powder at the time of regeneration is significantly increased compared to the conventional cement type. Decrease,
The recycling rate at the time of reuse is improved, and since the particle size is larger than before, the air permeability is improved, gas defects during casting can be prevented, and the solidification rate is increased due to the improvement of the thermal conductivity of skin sand. The mechanical properties of will be improved. Actually, using the mold of FIG. 1, copper alloy (JIS standard; A1BC
As a result of casting 3), a good casting without gas defects could be produced.

FIG. 2 shows a comparison of crushing resistance measurement results of a conventional mold using silica sand as a mold aggregate and a mold using granular slag as the mold aggregate of the present invention. The friability was calculated by the following formula. Crushability (%) = (grain size index after treatment−grain size index before treatment) / (grain size index before treatment) × 100

In the crushability test, the magnetic balls and the test aggregate were put in a pot mill, and the mixture was rotated at a rotation speed of 60 rpm for 20, 40 and 60 minutes, and then a sample was taken out to measure a particle size distribution. Compared with the case of conventional silica sand, the granular slag of the present invention having a similar particle size has a crush resistance of 5 times or more, and even in the case of a granular slag (0.6 to 1.2 mm) having a large particle size. The crush resistance is more than double that of conventional silica sand.

Further, a tensile test piece was sampled from a casting when the mold according to the present invention was used, and the results of examining the mechanical properties are shown in FIG. 3 in comparison with the conventional case. Compared with the conventional casting using a cement mold, the casting using the granular aluminum as the surface sand of the present invention and using the granular electric furnace slag as the back sand has a tensile strength improved by about 10%. are doing.

[0018]

As described in detail above, according to the copper alloy mold of the present invention, the following effects can be obtained. (1) Granular aluminum with alkaline phenol (binder) added as skin sand, and back sand with alkaline phenol (binder) added to granular slag by electric furnace slag quenching As a result, the crush resistance is improved and the generation of fine powder is significantly reduced, as compared with the conventional case where silica glass contains water glass or cement as a binder. (2) By using granular aluminum as skin sand, it is possible to improve the solidification of the casting and the cooling rate during cooling, so the structure of the product becomes finer and its mechanical properties improve. In particular, if the grain size of granular aluminum is set to 0.6 to 0.8 mm, the quality of the copper alloy casting will be significantly improved. (3) The electric furnace slag used as the back sand is superior in crush resistance to silica sand, which is a conventional mold aggregate, and has a particle size of 0.8
~ 1.2 mm and conventional mold material silica sand (particle size 0.3-0.8 m
If it is larger than m), the air permeability will increase, so
It is possible to remove the gas generated from the mold during pouring and solidification, thereby preventing the generation of gas defects that affect the mechanical properties of the cast product.

[Brief description of drawings]

1A and 1B show a structure of a copper alloy mold as an embodiment of the present invention, wherein FIG. 1A is a longitudinal sectional view thereof, and FIG.
The figure is a cross-sectional view thereof.

FIG. 2 is a graph showing a comparison of crushability between a conventional mold using silica sand as an aggregate and a mold using granular slag as an aggregate in the present invention.

FIG. 3 is a graph showing the strength test results of tensile test pieces taken from the casting by the mold of FIG. 1 in comparison with the conventional case.

[Explanation of symbols]

 1 Back sand layer 2 Skin sand layer 3 Inner mold

Claims (3)

[Claims] 1. A mold for casting a copper alloy, comprising:
A skin sand layer and a back sand layer that covers the outer surface of the skin sand layer are provided, and the skin sand that forms the skin sand layer consists of granular aluminum to which an alkali phenol was added as a binder to form the back sand layer. The back sand is characterized in that it is made of granular slag produced by rapidly cooling the electric furnace slag discharged when refining molten steel in an electric furnace from a molten state, to which alkali phenol is added as a binder. A mold for copper alloys. 2. The copper alloy mold according to claim 1, wherein the grain size of the granular aluminum is 0.6 to 0.8 mm. 3. The copper alloy mold according to claim 1, wherein the granular slag has a particle size of 0.8 to 1.2 mm.