JPH0466219A - Method and device for extruding metal - Google Patents

Abstract

PURPOSE:To make possible the near-net-shape work for extruding the hard-to- work material by heating the blank material in the container to the solid-liquid coexistence temperature range at just before the dies, extruding the body to be formed from the dies with the pressure corresponding to this state and cooling and solidifying again at the outlet of the dies. CONSTITUTION:The blank material 1, 2 of the metallic material of solid phase or the metallic base composite material is mounted in the container 3 of the extruder 3. The blank material 1, 2 is heated with the heating means 4 so as to reach the temperature range of solid-liquid coexistence. The pressure preliminarily set corresponding to the flow and deforming characteristic of this solid-liquid coexsistensive state is loaded to the extruding cylinder to form with extruding the formed body 7 of semi melted state from the extruding dies 5, then the body 7 is cooled rapidly at the outlet of the dies 6 and solidified again. Therefore, the extruded and formed products of near net shape of good quality can be obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) Particularly relevant to extrusion processing methods and extrusion processing equipment using metal (or alloy) materials and other metal matrix composite materials such as cermets. The results of research and development on advantageously realizing extrusion processing of the above material in the semi-molten, solid-liquid coexistence temperature range are disclosed herein.

(Prior art) The mainstream of extrusion processing of metal materials is generally hot extrusion, which utilizes the increase in plasticity caused by raising the temperature in a solid state, and recently cold extrusion of small parts has also become popular. However, the resistance to deformation is quite large.

By the way, attempts are being made to form a metal or alloy melt in a solid-liquid coexistence state obtained by stirring it under cooling, but the extrusion process is still far from the practical stage.
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In other words, conventional metal extruders are designed exclusively for solid-phase materials, and do not consider extrusion processing in a solid-liquid coexistence state; therefore, the materials used are limited to materials heated in a soaking furnace. It is not designed to heat inside the container.

Needless to say, metal in a solid-liquid coexistence state has a higher temperature than the hot material heated in a soaking furnace, so even when extruding hot material, the material of the conventional extrusion plunger tip makes it difficult to maintain high temperature. This is much more severe than the problems that often occurred during extrusion, and furthermore, there are difficulties with the material of the extrusion plunger tip, especially when extruding high melting point materials such as iron-based materials. There is no suitable material, and even if there was, it would be too expensive to use economically.

In addition, in conventional attempts at extrusion processing in a solid-liquid coexistence state, there is no concept of extrusion processing with a constant solid phase ratio, and there is no industrially usable solid phase rate sensor.

Furthermore, in conventional solid-phase extrusion, no device is provided for cooling the formed body at the exit of the die.

(Problems to be Solved by the Invention) When trying to extrude the metal (or alloy) material or metal matrix composite material in the semi-molten state described above, 1. Because of the high temperature, in conventional solid-phase extrusion, where the entire material is heated to a uniform temperature, the plunger tip that presses the end of the material is exposed to high temperatures, and the material of the plunger tip becomes an issue. 2. In order to obtain a homogeneous molded product, it is necessary to extrude with a constant solid fraction, but even if there is a method to detect the solid fraction and feed it back to the heating device, it is possible to 3. Semi-molten metal in a solid-liquid coexistence state grows crystals and becomes coarser over time. When the entire length of the material is heated, the time elapses from the start to the end of extrusion, so the crystal grain size differs between the tip and the rear end, making it impossible to obtain a homogeneous molded product, and the disadvantage of coarse crystal grains is added to the problem. This is pointed out as a point.

(Means for Solving the Problems) In the present invention, a material made of a solid metal material or a metal matrix composite material is charged into an extruder container, and heated to reach a solid-liquid coexistence temperature region immediately before an extrusion die. Then, by applying a preset pressure to the extrusion cylinder that corresponds to the flow or deformation characteristics in this solid-liquid coexistence state, the extrusion die extrudes the semi-molten material, forms it, and cools it at the exit of the extrusion die. A metal extrusion processing method (first invention) characterized in that the metal extrusion processing method (first invention) is characterized by applying and resolidifying the material, and an extruder container into which a material made of a solid phase metal material or a metal matrix composite material is charged, and this extruder container. The extruder container is equipped with an extrusion die placed at the tip of the extruder container and an extrusion cylinder that presses the material in the extruder container toward the extrusion die. A metal extrusion processing apparatus (second invention) is provided with a heating means for warming the metal, and a cooling means for resolidifying the semi-molten formed body on the exit side of the extrusion die.

The above configuration of the present invention is based on the following knowledge.

Since the extruded material is deformed or molded by the die, it is not necessary to heat the entire material inside the container, and it is sufficient to heat only the part that comes into contact with the extrusion die. If the heating of the material is limited to the vicinity of the die, the temperature of the part (rear end) of the material in contact with the extrusion plunger tip will not reach a high temperature, so the heat resistance quality of the extrusion plunger tip will not be a problem.

It has been experimentally confirmed that there is a certain relationship between the solid phase ratio of the material in the semi-molten state and the extrusion pressure, as shown in FIG. 1 in the case of Cu-15% A1 alloy, for example. Therefore, if the material is extruded with a constant extrusion pressure, molding can be achieved with a constant solid phase ratio.

Now, FIG. 2 shows a specific example of an apparatus that performs extrusion at a constant extrusion pressure in accordance with the above-mentioned procedure.

In Figure 2, numbers 1 and 2 are all used for extrusion processing,
The first and second materials, 3 are extruder containers into which the image materials 1 and 2 are sequentially charged, 4 is a heating means arranged on the tip side, 5 is an extrusion die, 6 is a die holder, 7 is a molded product,
8 is an extrusion cylinder, 9 is a pipe, 10 is a hydraulic system, 11 is an extrusion plunger tip, 12 is a plunger rod, and 13 is a cooling means for the molded body 7.

(Function) According to the first invention, the pressure of the extrusion cylinder 8 shown in FIG. 2 is first set to a predetermined pressure.

Next, the temperature of the material is raised by the heating means 4.

When the temperature rises and the material 1 reaches a predetermined solid phase ratio in a semi-molten state, extrusion molding using the extrusion die 5 is started.

At this time, the material 1 is heated such that the temperature near the extrusion die 5 is high and the temperature decreases toward the inlet.

When the material 1 reaches a predetermined solid phase ratio near the extrusion die 5 and extrusion is started, the material 1 advances forward.

As the material 1 moves forward, it is heated one after another and is extruded one after another at a constant solid phase ratio.

By locally raising the temperature of the material 1 near the extrusion die, the heating time of the material 1 becomes equal for both the front and rear ends of the material 1, and grain growth becomes uniform.

Furthermore, since this local heating takes an extremely short heating time compared to heating the entire length of the material, it does not cause much crystal grain growth and can prevent coarsening.

(Effect of the invention) According to the first invention, there are the following effects.

1. Near-net shape processing of materials that are difficult to extrude, which was previously difficult, is possible not only in cold processing but also in hot processing.

2. Also in this near-net shape processing, an extruded product that is homogeneous in the longitudinal direction can be obtained.

3. Since coarsening of crystal grains during extrusion processing can be prevented, high-quality near-net shape extruded products can be obtained.

4. No special material is required for the plunger tip.

5. Extrusion processing in a solid-liquid coexistence state is possible.

Furthermore, the method of the first invention is advantageously realized by the device of the second invention.

[Brief explanation of the drawing]

FIG. 1 is a graph of the relationship between the solid fraction of the semi-molten material and the extrusion pressure, and FIG. 2 is an explanatory diagram of the extrusion processing apparatus. 1.2...Material 3...Extruder container 4...Heating means 5...Extrusion die 8.
... Extrusion cylinder 13 ... Cooling means Fig. 1 till green

Claims (1)

[Claims] 1. A material made of a solid phase metal material or a metal matrix composite material is charged into an extruder container, heated to reach a solid-liquid coexistence temperature range immediately before the extrusion die, and By applying a preset pressure to the extrusion cylinder corresponding to the flow or deformation characteristics in a liquid coexistence state, a semi-molten material is extruded from the extrusion die, and is cooled and re-solidified at the exit of the extrusion die. A metal extrusion processing method characterized by: 2. An extruder container into which a material made of a solid metal material or a metal matrix composite material is charged, an extrusion die placed at the tip of this extruder container, and the material inside the extruder container is pressed toward the extrusion die. The extruder container is equipped with an extrusion cylinder, and the extruder container is equipped with a heating means adjacent to the extrusion die to raise the temperature of the charged material to the solid-liquid coexistence temperature range, and the semi-molten compact is recirculated on the exit side of the extrusion die. A metal extrusion processing device comprising cooling means for solidification.