JPH01166850A - Manufacture of copper or aluminum alloy casting - Google Patents

Abstract

PURPOSE:To improve the strength characteristic of a casting by molding by adding a bonding agent to the Al alloy grain having a specified grain diameter and casting a copper or Al alloy molten metal. CONSTITUTION:The Al alloy grain of 0.01-4mm grain diameter is prepd. and hardened by its kneading by adding the inorg. bonding agent of a sodium silicate, etc., or the org. bonding agent of oils, fats, etc., at specified rate to form the mold of high thermal conductivity. When casting is executed by pouring a copper or Al molten metal by using this mold, the defect generation caused on the hydrogen gas in the alloy casting is prevented due to the mold of high thermal conductivity having its excellent cooling effect. The casting of the copper or Al alloy of refined crystal grain is obtd. because the cooling effect is improved. The strength characteristics of the tensile strength, corrosion fatigue strength, etc., of the casting are thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing copper or aluminum alloy castings.

[Conventional technology]

Because aluminum alloy castings have high specific strength, and steel alloys have excellent corrosion resistance, they are often used as industrial equipment parts. There are two methods for producing these castings: (1) Sand casting method and (2) Die casting method. Most castings with complex shapes, large weights, and low production numbers are manufactured using the sand casting method. In addition, the mold casting method saves labor, improves the working environment, improves quality and dimensional accuracy by reducing casting defects, and has a high cooling rate, which saves on feeders, making it highly productive and economical. It has been widely adopted since then.

However, although mold casting is suitable for mass production because a mold is manufactured, it is not used for single-item manufacturing because the manufacturing cost of the mold is high.

This is because the mold is manufactured by precision casting and then further machining is performed, making the manufacturing cost relatively high.

Also, for sintered alloys in which steel grains are sintered, the sintering temperature is 1000℃.
In addition to the above, it also requires a compression molding machine, so it is limited to mass-produced small items.

For this reason, it is currently impossible to manufacture aluminum alloy blowers with thick walls and blades of up to 1000 m in length using sand molds. However, the amount of dissolved hydrogen in aluminum alloys in solid state is significantly lower than that in liquid state, that is, the amount of dissolved hydrogen in aluminum alloys is significantly lower than that in melted state. This not only caused defects, but also caused a decrease in mechanical properties and fatigue strength. In addition, copper alloys have excellent mechanical properties in the case of castings whose cooling rate is relatively fast, but in the case of sand mold castings, gas defects are likely to occur and the mechanical properties deteriorate, as with aluminum alloys. This tendency is particularly strong for both alloys when it comes to large castings. For example, using aluminum bronze, which is a copper alloy, the mechanical properties of small castings with a fast cooling rate are 68 kgf/-, but for large castings weighing about 20 tons, the mechanical properties are around 50 kgf/*-. descend. In addition, the corrosion fatigue strength in seawater is also determined by the number of repetitions 2
In 1 G' rotation, 18 kgf/s can be obtained with a small cast material, whereas this decreases to 10 kgf/s with a large cast material.

For the above reasons, large-sized copper or aluminum alloy castings are currently designed to have a thick wall thickness in consideration of actual strength. However, in recent years, small, lightweight, and highly efficient equipment has been required from the standpoint of energy conservation, and these are also required for copper or aluminum alloy castings.

[Problem that the invention seeks to solve]

The present invention provides a method for producing sound copper or aluminum alloy castings that have higher mechanical properties than current sand mold castings of copper or aluminum alloys, have less deterioration in mechanical properties even when large castings are made, and are free from gas defects. This is what we are trying to provide.

[Means for solving problems]

The present invention is a method for producing copper or aluminum alloy castings, which comprises pouring molten copper or aluminum alloy into a mold formed by adding a binder to aluminum alloy grains having a grain size of α01 to 4, and hardening the mold. It is.

The aluminum alloy grains referred to in the present invention include pure aluminum metal grains, and those having a grain size α01 to 4 m+ are used. By using particles with such a particle size, the air permeability of the S-type can be freely controlled depending on the copper or aluminum alloy to be cast and the shape of the product casting, and the casting surface of the cast product is also good, and the aluminum used This is because the cost of granulating the alloy particles is also low.

As aluminum alloy grains, in addition to pure aluminum, 1
Aluminum alloys containing up to 0% Si, Cu, MV may be used. If the alloy components are increased too much, the crack point will drop too much and the mold will become unsuitable, so care must be taken.

In addition to sodium silicate, the binder used in the present invention includes inorganic binders such as cement, organic binders such as oils and fats, starches, sugars, natural resins, and synthetic resins.

The blending ratio of aluminum alloy particles with particle size (LO 1 to 4 m) and binder is such that the thermal conductivity of the resulting mirror shape is at least (L
2Cat/"C-51-s6C or more.For example, taking the case of using silicate soda as a binder, aluminum alloy particles with a particle size of α01 to 4 are used. 15 to 2% by weight of sodium silicate
．． After adding OvtX and kneading, a mold having a desired thermal conductivity can be obtained by blowing Co1 and curing the mixture.

Since the present invention uses a mold with high thermal conductivity to pour and cast molten copper or aluminum alloy, it is rapidly cooled compared to conventional sand casting, which is not possible with conventional sand casting. A fine-grained copper or aluminum alloy casting without any hydrogen gas defects is obtained. Furthermore, the present invention can be applied to any production case, from small-sized castings with complex shapes to large-sized castings, from large quantities to single-item production, and the molds used are no different from conventional sand molds!
It is only a little heavy, so there are few problems in mold production.

When the casting alloy is an aluminum alloy, the casting temperature is generally 650 to 730°C.9For a copper alloy, the casting temperature is 1000 to 1200°C, which is higher than the melting point of pure aluminum, about 660°C. However, the mold used in the present invention has sufficient heat resistance due to the effect of the mold having good thermal conductivity, and corrosion of the surface of the mold by the molten metal can be avoided.

Hereinafter, the present invention will be explained in further detail by giving specific examples.

〔Example〕

Table 1 shows formulation examples for producing molds used in the present invention using sodium silicate (water glass) as a binder. Sodium silicate is made using No. J182, and curing is done by blowing CO snow gas (
tskg15-'', 1a min).

Table 1 The chemical composition and properties of the aluminum alloy grains shown in Table 1 are shown in Table 2 in comparison with the properties of foundry sand.

Table 2 Using only one of the aluminum alloy grains listed in Table 2, a mold was made according to Mixing Example A in Table 1, and molten copper or aluminum alloy having the chemical composition shown in Table 3 below was poured into the mold. It was boiled to produce castings.

Table 3 (a) and (b) in Table 3 are copper alloys, and the material is Tl5
Made of AtBC3 aluminum bronze! +, (C) is an aluminum alloy material [J I S AC8A or
yv mini alloy. Copper alloy, (a), (b)
is 1,120°C, and aluminum alloy (C) is 690°
I poured hot water at C.

Table 4 shows the mechanical properties of the copper alloy castings and aluminum alloy castings obtained by the above method.

In the case of aluminum bronze castings made of copper alloys, as shown in Table 4, the casting method of the present invention has a large cooling effect because it is rapidly cooled through aluminum alloy grains with good thermal conductivity.
), >) Tensile strength 6&7~6 as seen in materials
9f/- was obtained for a8, and the fatigue strength in seawater was also reduced to 2 repetitions.
X 10? 9f/- is secured between 17 and 18, and the tensile strength of the conventional casting method is 448 to 49.5 kgf.
/J seawater fatigue strength is significantly superior to 10kgf%-. Moreover, the aluminum alloy (c) of the present invention
Castings also have a tensile strength of 215 kgf/-, which is superior to conventional materials, which has a tensile strength of 145 kllf/*-.

Furthermore, the castings obtained by the present invention had fewer defects and were sound compared to castings made by conventional casting methods.

The corrosion fatigue test was conducted using a Weller rotary bending corrosion fatigue strength tester, with repetition rates S, 600 r, p, m,
The test was carried out using a test piece with a diameter of 6 m in natural seawater and at room temperature.

〔Effect of the invention〕

Copper alloy and aluminum alloy castings produced according to the present invention have fewer casting defects even when large-sized castings with thick walls, less deterioration of mechanical properties due to mass effect, high corrosion fatigue strength, and fine crystal grains. It has the characteristics that it is possible to obtain This is due to the quenching effect of the aluminum alloy grain mold used in the method of the invention.

Therefore, if the castings manufactured by the present invention are used as materials for equipment such as marine propellers and marine invera that require corrosion fatigue strength in isothermal water, these equipment can be made smaller and lighter717.
It can greatly contribute to energy conservation.

Claims (1)

[Claims] A method for producing copper or aluminum alloy castings, which comprises pouring molten copper or aluminum alloy into a mold formed by adding a binder to aluminum alloy grains having a grain size of 0.01 to 4 mm, and hardening the mold.