JPH1058086A - Structure for durable mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing man-hours for a planned casting part and to secure a durability of a product part by making a part surrounding a casting plan part in a durable mold with a pouring formed refractory and a part surrounding the product part with a metallic mold whose heat conductivity is larger than that of the refractory. SOLUTION: The durable mold 1 is composed of the refractory 2 consisting essentially of silicon carbide to the part surrounding the casting plan part composed of a sprue 2a, a runner 2b, gates 2c and a gas vent hole 2d and a metallic mold 3 consisting of a copper alloy to a part surrounding a product part 3a. The refractory 2 can be finished for short term of 2-3 days from the manufacture of a foaming styren pattern. The metallic mold 3 in the part surrounding the product part 3a and the refractory 2 are assembled to make the durable mold 1. At the time of casting by using the durable mold 1, the product part 3a secures the durability as the metallic mold 2 and further, the casting plan part can be reduced to the man-hours needed to the manufacture and the change as the refractory 2. Further, since the cooling of the casting plan part is slower than that of the product part, the supplement of molten metal from the casting plan part of the runner, etc., at the time of solidifying molten metal is executed and a feeder head can be unnecessitated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a durable mold for casting a casting at a low cost with few defects.

[0002]

2. Description of the Related Art When a cast iron-based casting is cast by forming the entire mold with a sand mold, casting defects due to sand typified by sand biting are likely to occur. In addition, casting using a sand mold has problems such as working environment and waste disposal, and it is necessary to take measures against them.

On the other hand, no sand such as a mold is used.
So-called durable molds have been attracting attention in recent years because of their potential to solve the problem of sand molds. For example, JP-A-3-47649
Japanese Patent Application Publication No. JP-A-2003-133873 discloses a mold for casting an aluminum alloy casting or the like for casting a casting having a feeder portion, a portion surrounding the feeder portion is provided with a heat insulating space, and a portion surrounding the product portion. There is disclosed a casting mold in which a shape portion such as a fin which easily radiates heat is provided, and a portion surrounding a product portion has a structure in which heat transfer is relatively easier than a portion surrounding a feeder portion. According to Japanese Patent Application Laid-Open No. Hei 3-47649, it is possible to obtain a casting free of casting defects by exerting a molten metal replenishing action from a feeder portion to a product portion and to reduce the volume of the feeder to improve casting yield. It can be done.

[0004]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 3-476 is disclosed.
In Japanese Patent No. 49, there is no air permeability, so it is necessary to consider degassing. Furthermore, since the mold has a high cooling capacity,
It is necessary to consider the size and arrangement of the runner, runner, etc. in consideration of the process from injection of the molten metal to solidification, and it takes more man-hours to determine the plan part than in the sand mold. In addition, since the mold is generally manufactured by machining, it takes a lot of time and money, and it is often difficult to change the plan part. From the above, when casting a casting using a durable mold such as a die, it takes a long time to start mass production, and this is the reason why the application field of the durable mold does not expand.

[0005] It is an object of the present invention to provide a durable mold structure in which a product part is a mold and a plan part is configured to be easily manufactured or changed.

[0006]

In order to solve the above-mentioned problems, a structure of a durable mold according to the present invention is such that a part surrounding a plan part is made of a cast refractory and a part surrounding a product part is a mold. It is characterized by. And the thermal conductivity of the refractory is made smaller than the thermal conductivity of the mold.

[0007] In the structure of the durable mold of the present invention, in particular, the plan portion is made of a cast-molded refractory which has high heat resistance and is easy to manufacture. Cast refractories are made by dissolving with water or an organic solvent to make a slurry, poured into a model made of a material that is easy to process such as styrofoam or a wooden mold, then cured and dried and fired. Can be manufactured between. The cast refractory can also be manually shaped into a gate, etc., before firing. Therefore, in the decision of the planning department such as the gate,
Normally, trial and error by test blowing is necessary, but if the mold part is made of cast refractory, many molds can be prepared at the same time, and the production time is short, so reflecting the previous casting result The period for changing the bill section is greatly reduced.

In addition, if a material having a lower cooling capacity, that is, a material having a lower thermal conductivity than the mold of the product part is selected as the cast refractory constituting the plan part, the runner or weir serving as the plan part can be formed. By reducing the cooling of the molten metal during the passage and increasing the temperature of the molten metal injected into the mold of the product part, the flow of the molten metal in the product part is improved. Furthermore, in the casting, since the solidification of the casting part is slower than that of the product part, the molten metal is supplied from the casting part to the product part at the time of solidification shrinkage, thereby suppressing shrinkage of the product part.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a main part showing a structure of a durable mold according to an embodiment of the present invention. The durable mold 1 is used to cast eight spherical graphite cast iron (JIS) FCD800 with a mass of about 500 g. Durable mold 1
A refractory 2 mainly composed of silicon carbide, which surrounds a portion surrounding a plan portion including a gate 2a, a runner 2b, a weir 2c, and a gas vent hole 2d;
A part surrounding the product part 3a is a mold 3 made of a copper alloy. The refractory 2 is manufactured by first forming a silicon carbide 90 by mass ratio.
%, Alumina 4%, silica 3% and cement as a hardening agent, and a powder having a particle size of 100 μm or less is prepared, and 8% of water is added to the powder to prepare a slurry. Before the slurry is prepared, a model is prepared using styrofoam according to the shape of the refractory. Next, the refractory 2 is completed by pouring the slurry into the model, hardening, removing the mold, drying and sintering. The refractory 2 described above can be completed in a short period of two to three days after the production of the styrofoam model. Further, the mold 3 and the refractory 2 at the portion surrounding the product portion 3a can be assembled to form the durable mold 1.

When the casting is performed using the durable mold 1 of the present embodiment, the product part 3a is used as the mold 3 to ensure the durability, and further, the plan part is used as the refractory 2, so that the man-hour required for manufacturing and changing is reduced. it can. Further, since the cooling of the plan part is slower than that of the product part, the molten metal is replenished from the plan part such as a runner at the time of solidification of the molten metal, so that a riser can be unnecessary.

FIG. 2 is a sectional view showing the structure of a mold of a comparative example, and shows a case where the present invention is applied to a product similar to the embodiment of the present invention. The mold 11 includes a gate 12a, a runner 12b, a weir 12
c, a portion surrounding the plan portion 12 composed of the gas vent hole 12d and the feeder 12e and a portion surrounding the product portion 13a are made of the same material copper alloy. When the plan part 12 is changed, it is necessary to use overlay welding or machining, which requires a large number of man-hours and costs. In addition, depending on the material of the mold 11, it is difficult to build-up welding, and it may take about 10 days to perform build-up welding and machining.
It may take about one month to re-make the whole. In addition, since the mold 11 has the same thermal conductivity as the product part 13a and the plan part, there is extremely little supply of molten metal from the plan part such as a runner at the time of solidification of the molten metal. It is necessary to control coagulation by forming a passage or the like, and the structure tends to be complicated.

[0012]

As described above in detail, in the structure of the durable mold of the present invention, the portion surrounding the plan portion is a cast refractory, and the portion surrounding the product portion is a mold. And since the thermal conductivity of the refractory is smaller than the thermal conductivity of the mold, the durability of the product part is secured, and the man-hour required for manufacturing and changing the plan part can be reduced, which is a significant economical effect. To play.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing a structure of a durable mold according to an example of an embodiment of the present invention.

FIG. 2 is a sectional view of a main part showing a structure of a mold of a comparative example.

[Explanation of symbols]

1: durable mold, 2: scheme part, 2a: gate, 2b: runner, 2c: weir, 2
d: vent hole, 3: mold, 3a: product part,
11: mold, 12: scheme part, 12a: gate, 12b: runner, 12c: weir, 1
2d: vent hole, 12e: hot water, 13a: product part.

Claims (2)

[Claims] 1. The structure of a durable mold, wherein a part surrounding the plan part is made of a cast refractory, and a part surrounding the product part is made of a mold. 2. The structure of claim 1, wherein the thermal conductivity of the refractory is smaller than the thermal conductivity of the mold.