JPH06210424A - Die casting method of partially solidified metal - Google Patents

Abstract

PURPOSE:To promote the homogeneity of the solidifying structure by setting the flow speed of the partially solidified metal in passing the gate not to exceed the prescribed value when the partially solidified metal is injection formed. CONSTITUTION:The stock 2 inserted in a sleeve 1 is heated to the temperature where the prescribed solid phase ratio is obtained by an induction heating coil 3. When the partially solidified metal 2 in the temperature range above the liquidus and below the solidus is injection formed to a die 6 through a gate 5 by operating a plunger 4, the flow speed of the partially solidified metal in passing the gate 5 is set to <=50m/s. This constitution allows the solid phase particles which are solid in the partially solidified condition to be dispersed even to the surface layer part of the die casting, realizing the homogenized structure. The flow speed of the partially solidified metal in passing the gate can be adjusted by the injection speed of the plunger 4, the shape of the gate 5 or the like when the section of the stock 2 is constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die-casting method for semi-molten metal, and particularly proposes a method for producing a die-casting product having a uniform structure and less segregation.

[0002]

2. Description of the Related Art In general die casting, molten metal is supplied to a sleeve and immediately injected into a mold cavity by a plunger to solidify the molten metal in the mold to obtain a product.
In order to obtain products with good surface quality, we have devised ways to control the injection speed and rolling force, as well as the shape of the mold.

However, in the case of die casting of semi-molten metal,
Problems have been encountered that were not found in conventional molten metal die casting. That is, when the cross-sectional metallographic structure of the semi-molten metal die-cast product was observed, the solid phase particles that were solid in the semi-molten state did not exist in the surface layer portion, and accordingly, segregation of the components occurred. Such component segregation, that is, uneven distribution of solid-phase grains, causes various problems such as insufficient strength and elongation of the final product and deterioration of corrosion resistance.

In the semi-molten metal, the composition of the alloy is usually different between the liquid phase and the solid phase. Due to casting, the part that was in the liquid phase in the semi-molten state was rapidly solidified, and the part originally solidified. The component composition differs from the part that was a phase.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to advantageously solve the above-mentioned problems, and to propose a die casting method of a product having a uniform composition with less component deviation due to die casting of semi-molten metal. To do.

[0006]

Means for Solving the Problems The gist of the present invention is, when a semi-molten metal in a temperature range below a liquidus line and above a solidus line is injected into a mold cavity through a gate to be molded, when passing through the gate. Is a die-casting method for semi-molten metal, characterized in that the uniform flow rate of the semi-molten metal is set to 50 m / s or less to promote uniform organization of the solidified structure.

[0007]

The background of the present invention and its operation will be described below. A semi-molten metal die-cast product does not have solid-phase particles that were solid in the semi-molten state in the surface layer, and has a non-uniform structure, which deteriorates product quality. Overlaid.

As a result, the flow rate of the injection stream of the semi-molten metal has a great influence on the dispersion state of the solid phase particles, and when the flow rate is high, solid phase particles are not seen in the surface layer of the product. It was also revealed that the solid-phase particles were dispersed.

It has been found that the flow velocity of the injection stream of the semi-molten metal is optimally controlled by the flow velocity of the semi-molten metal when passing through the gate, and the upper limit of the flow velocity is 50 m / s. Therefore, in order to obtain a product having a uniform structure in the die-casting of semi-molten metal, it is necessary to set the flow rate of the semi-molten metal at the time of passing through the gate to 50 m / s or less.

The flow velocity of the semi-molten metal when passing through the gate is
When the material cross section is constant, it may be adjusted by the injection speed (plunger speed), the shape of the gate, and the like.

[0011]

[Example] Dimensions: 60 mmφ x 70 mm Al-4 mass% S
The i-alloy material is heated to a semi-molten state with a solid phase ratio of 0.4 and injection-molded using the die casting machine shown in Fig. 1, and the thickness is 3 m.
A plate-like product having m, a width of 100 mm and a length of 150 mm was manufactured.

FIG. 1 is an explanatory view of the die casting machine,
In the figure, 1 is a sleeve, 2 is a material, 3 is an induction heating coil for heating the material 2, 4 is a plunger, 5 is a gate, 6 is a mold, 7 is a mold sleeve, and 8 is a shunt. In the injection molding by this die casting machine, after the material 2 inserted in the sleeve 1 is heated by the induction heating coil 3 to a temperature at which the solid fraction is set to a predetermined solid fraction, the plunger 5 is operated to heat the material to the mold sleeve 7, It is injected into the cavity of the mold 6 through the gate 5 and molded.

In the production of the above plate-shaped products, as a conformity example of the present invention, conditions of injection speed: 2 m / s, gate width: 60 mm, flow rate of semi-molten metal when passing through the gate: 50 m / s, and as a comparative example. The injection speed was 3 m / s, the gate width was 30 mm, and the flow rate of the semi-molten metal when passing through the gate was 75 m / s. The metallographic structure of each of the products thus obtained was investigated. Each of these metallographic photographs is shown in Figure 2.
(Compatible example) and FIG. 3 (Comparative example). As is clear from these figures, in the conformity example of FIG. 2, the solid-phase particles that were solid in the semi-molten state are seen to be dispersed in the surface layer part as well.
In the comparative example of FIG. 3, the solid phase grains are not seen in the surface layer portion.
The white parts in these photographs are solid phase particles.

[0014]

According to the present invention, when a semi-molten metal is injected into a mold cavity through a gate for molding, the flow rate of the semi-molten metal when passing through the gate is regulated to make the semi-molten metal uniform. According to the present invention, a die-cast product having a structure is produced, and a product of good quality with less segregation can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a die casting machine used in an example.

FIG. 2 is a photograph of a metal structure of a conforming example of the present invention.

FIG. 3 is a photograph of a metal structure of a comparative example.

[Explanation of symbols]

 1 Sleeve 2 Material 3 Induction Heating Coil 4 Plunger 5 Gate 6 Mold 7 Mold Sleeve 8 Shunt

Front Page Continuation (72) Inventor Chisato Yoshida 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Stock company Rheotech

Claims (1)

[Claims] 1. When a semi-molten metal having a temperature range below the liquidus and above the solidus is injected into a mold cavity through a gate for molding, the flow velocity of the semi-molten metal when passing through the gate is 50 m / s. The following is a die-casting method for a semi-molten metal, characterized in that it promotes uniform organization of a solidified structure.