JPS61169113A - Extruding method of composite material - Google Patents

Abstract

PURPOSE:To perform the extrusion of high working rate and to rationalize its working process by extruding a composite billet consisting of at least two kinds of different metallic materials under a specific low temperature. CONSTITUTION:A billet 4 and a pressure medium 3 are housed in a container 1, and a stem 2 is advanced to compress isotropically the billet 4 through the medium 3 in order to form the billet 4 into the prescribed dimensions through a die 5. The billet temperature is <=-30 deg.C, when extruded. The friction between the billet 4 and the die 5 is reduced by the lubricating action of medium 3, and a second extruded from 6 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for extruding a composite fillet made of at least two different metal materials.

[Prior art and its problems] For example, when extruding composite billets 1 to 1 to manufacture a composite material in which low-melting point metals such as tin and lead are part of the constituent materials, the work is carried out at warm or room temperature. This is common practice, but if you try to extrude to a high degree of processing, defects such as surface layer defects or core material breakage, which are unique to composite materials, will occur, making it impossible to obtain a sound extruded material. This is inefficient work with low machining rate.

The purpose of the present invention is to eliminate the drawbacks of the prior art, and to create a composite material in which a low-melting point metal that is difficult to process is used as a part of the constituent material, or a metal material whose deformation resistance ratio at low temperatures is greater than 2. It is an object of the present invention to provide a method and a method capable of efficiently extruding billets 1 to 1 with a high degree of processing.

[Summary of the Invention] That is, the gist of the present invention is characterized in that the composite billet is extruded at a low temperature of -30°C or lower.

Processing at such low temperatures reduces the hardness ratio, or deformation resistance ratio, of the metal materials that make up the composite billet, allowing stable and sound extrusion of even difficult-to-process composite materials. can do.

Note that the extrusion processing method may be a normal method, that is, a ram extrusion method, but if it is a hydrostatic extrusion method that utilizes the isostatic compression force of a pressure medium, the friction between the fillet and the tool will be reduced. It is desirable to employ this extrusion method because it is easy to extrude to a high degree of processing, and the pressure medium serves as a heat insulating material, reducing temperature changes in the billet.

To obtain a low temperature of -30'C or less, a refrigerant such as dry ice or liquid air may be used, or a refrigerant machine may be used to cool the billet material to a predetermined temperature. However, when the billet material is cooled, the surrounding pressure medium is also cooled, which increases the viscosity of the pressure medium and may cause wrinkle-like defects in the extruded material.
It is desirable to take measures to reduce the viscosity of the pressure medium. Usually, in industrial isostatic extrusion, castor oil is used as the pressure medium, but castor oil alone at a raised temperature is injected into the equipment, or a mixture of castor oil and light oil is used. It is desirable to reduce the viscosity or use other low viscosity pressure media. The viscosity of the pressure medium is preferably 200 hexes or less of hinge oil at room temperature. Examples of the low melting point metal constituting the composite billet include spears, lead alloys, tin, and tin alloys.

"Example" Examples will be described below.

Figure 1 shows the principle of hydrostatic extrusion. In this extrusion method, the billets i~■ and the pressure medium ■ are housed in the container ■, and the stem ■is advanced from one end of the antenna ■. , the billets I and (■) are processed by applying isotropic contraction force to the pressure medium (2), and are processed into predetermined dimensions from the die (2).

In this case, the pressure medium ■ is between the billet ~ ■ and the die ■.
The lubrication effect reduces friction and results in a sound extruded material■.

A specific example of the present invention is a 100tf based on this principle.
Using a hydrostatic extrusion device, a lead alloy (PB-41OSB) coated aluminum material with an outer diameter of 25φ and a coverage rate of 25% was passed through a full-width die or a 60' and 90' conical die into 2.5φ and 4.5φ, respectively. Hydrostatic extrusion was carried out under various temperatures.

The results are not shown in Table 171.

In the cases marked with an X in the table, defects occurred in the extruded material, where the lead alloy coating material was excessively extruded against the aluminum core, resulting in a bamboo knot-like shape, and in the cases marked with a Δ. This is a case where the soft lead alloy coating material is not sufficiently drawn into the die (2) and stagnates before the die 0, resulting in a bulge-like defect.

To summarize the results in Table 1, as the billet temperature increases during extrusion, defects are more likely to occur, and when the die angle is slightly small (60'), the defects are bamboo knot-shaped outer layer defects of the extruded material. However, when the die angle is large, 90°, defects in the extruded material and bulge defects in the billet material occur. Regarding the extrusion size, as the extrusion size decreases from 4.5φ to 2.5φ, defects are more likely to occur, and defects occur even in O'C.

As can be seen from Table 1, the billet temperature during extrusion is -3
The lower the temperature is below 0'C, the higher the extrusion ratio, and the extrusion ratio (cross-sectional area ratio before and after extrusion) is 31 to 10.
0 processing is possible.

The processed material extruded in this way is subjected to surface reduction processing such as wire drawing in the next process to obtain the required product size. The reason why the extrusion temperature can be lowered to allow for sound extrusion without defects is due to the temperature characteristics of the billet components. It shows the temperature change characteristics of hardness and the temperature change of hardness ratio.

As the temperature increases, the Vickers hardness decreases, and this change is shown by two straight lines when the Vickers hardness is expressed logarithmically, and it decreases rapidly on the high temperature side. Accordingly, the hardness ratio between the core material, aluminum, and the coating material, which is a lead alloy material, increases rapidly at a high temperature of 130'C or higher. This phenomenon in which the hardness ratio of the billet inner and outer layer materials, that is, the deformation resistance ratio, increases rapidly at high temperatures is due to the following:
Low melting point metal (here lead alloy) as billet constituent material =
6- is used, and the temperature dependence is particularly difficult.

However, in the case of extrusion processing of composite materials, it is known that outer layer defects are likely to occur due to the deformation resistance ratio of the constituent materials, which are knot-like like bamboo and bamboo. It is possible to imagine that this has occurred.

Furthermore, when extruding at a high working degree such as an extrusion ratio of 30 to 100, heat generation during processing is large, and the temperature rise during extrusion is as large as 150 to 200'C in the case of a lead alloy/aluminum material. That is, O'C
When the billet ■ is extruded, the temperature of the extrusion mill at the exit of the goose plate becomes 150 to 200'C, and as is clear from Figure 2, the hardness ratio of the inner and outer layers of the processed material increases rapidly. The ratio was as large as 3 to 5, which is considered to be the cause of the defect occurrence. -30'C
When the following billet (2) is used, the extrusion (A) humidity temperature is at most 120 to 170'C or less, and the hardness ratio is about 3 or less, indicating that sound extrusion processing is possible.

In particular, the temperature rise (Δc) during extrusion processing can be determined by the following formula.

ΔT-ni-P JρG Here, P: extrusion pressure, K: wire breakage coefficient (approximately 0.7 in the case of hydrostatic extrusion), J: output equivalent, ρ: density, C: specific heat.

In the embodiments of the present invention, an example of a fishing alloy-coated aluminum material is shown as a composite billet containing a low-melting point metal. Also, extruding at a temperature of -30'C or lower has a great effect.

In Figure 2, it was shown that the change in hardness with temperature is expressed by two straight lines. Metal materials generally have this tendency, and the intersection of the two straight lines is expressed in absolute temperature in the case of pure metals. It is said that it becomes 0.55Te (King e: melting point). The difference in hardness decreases as the temperature decreases, -30'
Extruding at a temperature of C or lower makes it difficult for defects to occur. For example, various superconducting materials that can be extruded with a press power of 42 should be extruded at a temperature of -30'C or lower.1. II The benefits are great. In particular, in the internal diffusion method or solid-liquid diffusion method, when the billet constituent materials contain tin or tin-copper alloy, sound extrusion is possible, and a compound layer at the interface is not formed, making the wire drawing operation in the next step stable. Ultimately, the superconducting properties of the wire will also improve.

Although the embodiments have shown a configuration in which the outer layer is soft, the same effect can be obtained in the opposite case.

[Effects of the Invention] The present invention as described above has the following effects.

(1) It becomes possible to extrude highly processed materials, streamlining the process.

(2) By increasing the extrusion ratio, the adhesion of the composite material interface is improved, making the wire drawing operation in the next step easier.

(3) Structures that cannot normally be extruded because the deformation resistance of the constituent materials is proportionally large can now be extruded.

(4) In the case of extruded materials or superconducting materials, there is less heat influence and the final superconducting properties are improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of hydrostatic extrusion used in an embodiment of the method according to the present invention, and Fig. 2 shows the temperature change characteristics and hardness of the aluminum material and lead alloy material used in the embodiment. 3 is a graph showing changes in the ratio. 1: container, 2 system, 3: pressure medium, 4: composite billet, 5: die, 6: extrusion mill.

Claims (4)

[Claims] (1) A composite material extrusion method characterized by extruding a composite billet made of at least two different metal materials at a low temperature of -30°C or lower. (2) The extrusion method according to item 1 above, wherein one of the constituent materials of the composite billet is a low melting point metal. (3) The extrusion method according to item 1, wherein the composite billet is composed of a metal material having a deformation resistance ratio of more than 2 at room temperature. (4) The extrusion method according to item 1, item 2, or item 3, wherein the extrusion process is hydrostatic extrusion.