JP2003285154A - Low pressure casting apparatus for aluminum alloy material with dispersed particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent impurities contained in molten metal introduced in a cavity of a die through a stoke from being left in a product, in a low pressure casting apparatus for particle dispersed alloy materials like an aluminum alloy material dispersed with ceramic particles, or the like. <P>SOLUTION: In the low pressure casting apparatus for particle dispersed aluminum alloy material used for the low pressure casting method by which the molten metal in a melting furnace is pressurized to be admitted into the sprue of the die through the stoke, an impurities collector where impurities like oxides or the like accumulate is provided at an upper part of the die cavity mounted on a die stand. Preferably, the impurities collector is shaped to open downward, enabling the collector to collect the impurities of low specific gravity floating upward. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure casting apparatus used in a low pressure casting method of a particle dispersed alloy material such as an aluminum alloy in which ceramic particles are dispersed.

[0002]

2. Description of the Related Art Since aluminum alloy castings have a smaller specific gravity than iron and steel castings, they are remarkably lightweight even if they have the same shape and size. Therefore, it is widely used as a material for automobiles, industrial vehicles, railroads, etc., as well as electricity, communication equipment, daily necessities, etc. In recent years, for example, Al
-Cu-based, Al-Mg-based, Al-Si-based and other aluminum alloys are further compounded with ceramics, etc. to further enhance specific properties and develop for specific purposes. There is.

Molded bodies such as ceramics (generally called preforms) are used for composite aluminum alloy castings.
There is a particle-dispersed aluminum alloy casting in which is uniformly dispersed in a molten aluminum and strengthened. In general, a fiber-reinforced aluminum alloy casting is cast by preliminarily prepared preforms and aluminum with the composite ratio determined in advance. On the other hand, in a particle-dispersed aluminum alloy casting, a raw material in which certain particles (such as ceramic particles) have been prepared in advance in an aluminum alloy is melted and the particles are uniformly dispersed and cast, or prepared individually. A certain amount of particles are added to the molten aluminum alloy thus obtained and casting is performed. A method for producing a particle-dispersed aluminum alloy casting is one in which two types of ceramic particles are uniformly dispersed (Japanese Patent Laid-Open No. 4-297535).
No.), and an apparatus and method for optimally dispersing particles (Japanese Patent Laid-Open No. Hei 7 (1999) -1999).
No. 90423) and the like are known. These methods are
The main purpose is to produce a desired finished product by mixing and dispersing a certain composite material in an aluminum alloy.

One example of the particle-dispersed aluminum alloy casting is applied to a brake disc of an automobile or a railroad vehicle. Instead of the conventional cast iron material, speeding up further J
Vehicles for the R Shinkansen, etc. are aimed at material conversion to aluminum alloy castings in order to meet the proposition of further improvement of friction characteristics and weight reduction of vehicles, aiming at further enhancement of friction characteristics, aluminum-based mother alloy In addition, the development of uniformly dispersing and strengthening ceramics is underway. For example, A
One in which Al ₂ O ₃ particles or SiC particles are dispersed in an 1-Mg alloy (Japanese Patent Laid-Open No. 3-47945) and a brake disk in which SiC particles are uniformly dispersed in an Al-Si alloy in an amount of 5 to 30% are proposed. It has become a field of attention as an effective means for strengthening the properties required for specific members.

By the way, in the particle-dispersed aluminum alloy melt, complicated reaction elements such as difference in melting point, difference in specific gravity, ionization tendency, wettability, and the like are entangled with each other, resulting in physical and chemical peculiar technical difficulties. Is accompanied by. In addition, especially in terms of fluidity which is an index of the ease of making in producing a cast product, the fluidity of the particle-dispersed aluminum alloy melt is higher than that of the aluminum alloy melt by the physicochemical properties of both the aluminum and the particles. Are intricately intertwined,
It's very bad. For this reason, the flow of the molten metal deteriorates, the molten metal does not sufficiently reach the mold, and so-called casting defects called blow holes appear on the surface of the cast product.

[0006]

When a casting maker produces a cast product, a gravity casting method, a low pressure casting method, a high pressure casting method, or another special casting method is adopted as the casting method. Among these, the low pressure casting method, which is often used for casting aluminum wheels for automobiles, is widely used as a relatively economical and high quality casting method. However, since the fluidity of the particle-dispersed aluminum alloy melt is poor, if an aluminum alloy casting made from the particle-dispersed aluminum alloy melt is manufactured by the normal low-pressure casting method, is it possible to maintain the same quality as aluminum wheels for automobiles? That's a big question.

Using a particle-dispersed molten aluminum alloy,
In order to produce a high-quality cast product by the low-pressure casting method, it is essential to improve the fluidity of the particle-dispersed aluminum alloy melt, eliminate the cause of blowholes, or improve both. It is indispensable to increase the appearance rate of blowholes by low-pressure casting the particle-dispersed aluminum alloy melt by the same means and method as those for ordinary aluminum alloy melts. It is an issue that cannot be avoided from the point of view.

In the low-pressure casting method, pressure is applied to the surface of the molten metal to raise the molten aluminum through stalk, and the molten metal is poured into the mold. 3 and 4 show a conventional low-pressure casting apparatus, in which a mold 1 including an upper mold 1a and a lower mold 1b is placed on a mold base 2 via a packing 7, and a mold base 2 is provided. A sleeve 3 communicating with the sprue of the lower die 1b is inserted in the. On the other hand, a crucible 12 that holds and holds the molten metal is provided inside the melting furnace 10, and a stalk 5 that serves as a passage for the molten metal to the mold is provided inside the crucible.
A flange 5a is integrally provided on the upper end portion of the stalk 5, and is pressed and fixed to the lower surface of the mold table 2 via packing 7 by a plurality of cylinders 13 provided on the lid 11 of the melting furnace.

By the way, inclusions such as blows and oxides (hereinafter referred to as "impurities") exist inside the particle-dispersed aluminum alloy melt. At the time of casting, most of these impurities float to the upper part of the cavity of the mold, and at the end of casting, many blowholes and inclusions appear in this part, that is, the upper part of the product, which raises the problem of increasing the product defect rate. .

It is extremely difficult to eliminate the existence of the above-mentioned impurities, and since it is inevitably present in the molten metal, defective products based on these can be easily removed after casting. It is effective to do. Therefore, it is an object of the present invention to provide a low pressure casting apparatus capable of preventing the generation of defective products due to the above impurities.

[0011]

In order to solve the above problems, the present invention provides the following method. That is, the low-pressure casting apparatus for a particle-dispersed aluminum alloy material according to the present invention is a casting apparatus used in a low-pressure casting method in which a molten metal in a melting furnace is pressurized and introduced into a gate of a mold through a stalk. At the top of the cavity of the mold placed on
It is characterized in that an impurity reservoir for accumulating impurities such as oxides is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below. 1 and 2 are vertical sectional views showing an example of a low pressure casting apparatus of the present invention.
Reference numeral 0 includes a mold 1 including an upper mold 1a and a lower mold 1b, a mold base 2 on which the mold is placed, and a melting furnace 10. A crucible 12 for holding and holding a molten metal is provided in the melting furnace 10, and an opening of the crucible is covered with a lid 11 of the melting furnace. In addition, the lid 11 is connected to the crucible 1 from an external gas supply device.
An injection pipe 15 with a valve (not shown) for introducing an inert gas (or air) such as nitrogen gas for pressurization is provided in the inside of 2.

A stalk 5 is provided in the crucible 12. The lower end of the stalk 5 is located in the lower part of the crucible, and the upper end is provided with a flange 5a. The flange 5 a is pressed upward by the plurality of hydraulic cylinders 13 installed on the lid 11 and pressed against the lower surface of the mold base 2 via the packing 7. This cylinder 1
By contracting 3 the stalk 5 can be separated from the die stand 2 and the melting furnace 10 can be moved laterally. Therefore, the alloy can be melted and agitated at another location, carried into the casting position immediately below the die, fixed with the cylinder, and cast.

On the other hand, the mold 1 is placed on the mold base 2, and an upward force is applied to this mold during casting, so that the frame 25 provided on the side of the mold is bolted. It is fixed to the die stand 2 at 26 so that the die cannot be lifted. A vertical through hole is provided in the mold base 2, and the sleeve 3 is attached in a fitted state in the through hole. Further, a recess 6 is provided on the bottom surface of the lower mold 1b, and the upper end of the sleeve 3 is fitted into this recess. The outer diameter of the sleeve 3 and the inner diameter of the recess 6 are substantially the same, and the sleeve 3 is fitted without a gap. The lower surface of the sleeve 3 is flush with the lower surface of the mold base 2.

The upper mold 1a of the mold 1 has an impurity reservoir 4
0 is provided. The impurity reservoir 40 is a space portion that is originally formed in the upper portion of the casting cavity 45, and preferably has an inverted funnel shape with a widened bottom portion so that floating impurities can be easily accommodated. In the illustrated example, the impurity reservoir 40 is formed in a trapezoidal cross section in which the lower side gradually becomes wider.

When casting a particle-dispersed aluminum alloy using the low-pressure casting apparatus 100, a pressurized inert gas such as nitrogen gas is introduced from the injection pipe 15 into the crucible 12 containing the molten metal M. By the pressure of this gas, the molten metal in the crucible rises through the stalk 5, passes through the sleeve 3 and the runway 1c of the mold 1, and is introduced into the cavity of the mold from the sprue 1e. At this time, the air in the mold is exhausted through the mating surface 1d of the mold, and the air in the stalk 5 is exhausted through the mating surface of the mold and the gap between the stalk 5 and the mold base 2. It Since the impurity F contained in the molten metal has a small specific gravity, it floats up during this casting and is accommodated in the impurity reservoir 40 above the cavity and does not remain in the original casting cavity. The pressure of the molten metal becomes the highest, and the valve of the pressurizing pipe 15 is closed while the molten metal is distributed in the mold.
The point of dropping the molten metal in the stalk 5 and solidifying the molten metal in the mold is the same as in the conventional technique.

When the solidification in the mold is completed, the pressurization by the inert gas is stopped, the exhaust valve (not shown) is opened to release the pressure, and then the upper mold 1a is lifted to take out the cast product. Then, the mold is closed and casting is performed again. When the molten metal M becomes low or when stirring is required, the cylinder 13 is contracted and the stalk 5 is slightly lowered to disconnect the melting furnace 10 from the mold table 2, The melting furnace 10 may be laterally moved to a predetermined melting position to replenish and stir the molten metal, and then the molten furnace may be installed directly below the mold 1 to perform casting.

In the low-pressure casting apparatus 100, since the impurity reservoir 40 communicating with the original casting cavity is provided above the cavity of the mold 1, impurities having a small specific gravity in the molten metal float up during casting, The impurity pool 4
No impurities are present in the original casting cavity. After casting, the solidified cast product may be taken out of the mold, and the portion of the impurity pool above it may be removed by grinding, cutting, or the like. As a result, a high quality product without blowholes can be obtained. It should be noted that the impurity reservoir 40 may be any one that can contain as many impurities as possible, and its shape, dimensions, etc. are not particularly limited.

[0019]

As described above, if the casting apparatus according to the present invention is used, inclusions such as blows and oxides contained in the molten metal before solidification of the molten metal progresses in the mold. Since these are stored in the impurity reservoir provided in the mold, these impurities no longer exist in the original casting cavity, and high quality products can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a low pressure casting apparatus of the present invention.

FIG. 2 is an enlarged sectional view showing the cast state.

FIG. 3 is a sectional view showing a conventional low pressure casting apparatus.

FIG. 4 is an enlarged sectional view showing the cast state.

[Explanation of symbols]

1 mold 2 Mold stand 3 sleeves 5 Stoke 10 melting furnace 12 crucible 11 lid 13 hydraulic cylinder 15 Pressurized gas pipe 40 Impurity pool 100 low pressure casting equipment

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshimasa Hirai             1-12-19 Kitahorie, Nishi-ku, Osaka City, Osaka Prefecture             Kurimoto Iron Works Co., Ltd. F-term (reference) 4E014 NA02

Claims (2)

[Claims] 1. A casting apparatus used in a low-pressure casting method in which a molten metal in a melting furnace is pressurized and introduced into a gate of a mold through a stalk, and the mold cavity is mounted on an upper portion of the mold. A low-pressure casting apparatus for a particle-dispersed aluminum alloy material, which is provided with an impurity reservoir for accumulating impurities such as oxides. 2. The low pressure casting apparatus for a particle-dispersed aluminum alloy material according to claim 1, wherein the impurity reservoir is formed in a shape having a trapezoidal cross section that spreads downward.