JPS6145922Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a composite billet for high temperature isostatic extrusion. Conventionally, as a billet used to extrude a composite material made by combining different materials under high temperature isostatic pressure, a composite billet in which the outside of a core material 1 is covered with an outer covering material 2 is used, as shown in Fig. 1. 3 is used.
This composite billet 3 was completely sealed from the outside so that the pressure medium during extrusion would not enter the interface between the core material 1 and the outer covering material 2. However, since the core material 1 and the outer sheath material 2 are fitted together after being machined, a gap 4 always exists between them. This gap 4 is usually 0.1mm to 1.0mm.
The air sealed in this gap 4, which is generally on the order of mm, is not discharged to the outside even during extrusion molding, causing various defects in the product. In other words, if air is present between both interfaces, slippage will occur between the core material 1 and the outer sheath material 2 during extrusion, resulting in a failure to obtain a sound composite material, or even if extrusion is possible, the extruded product Defects such as pristars occurred in the process, leading to a decline in quality. Therefore, as a solution to the above-mentioned drawbacks, a method described in Japanese Patent Publication No. 51-21948 has already been proposed. According to this prior art, air present in the gap between the billet jacket material and the core material is discharged during extrusion molding. However, although this conventional method can be applied to cold isostatic extrusion, it is difficult to apply it to high temperature isostatic extrusion. That is, in high temperature extrusion, the composite billet must be heated to a predetermined high temperature before extrusion. However, when heating at this high temperature, if air is present at the interface between the jacket material and the core material, oxidation occurs and there is a problem in that good interfacial bonding cannot be obtained. Therefore, an object of the present invention is to provide a composite billet for high-temperature isostatic extrusion that allows air to be expelled during heating and provides good interfacial bonding. Therefore, its feature is that it is a composite billet for high-temperature isostatic extrusion, in which the outer covering material and the core material are integrated in a composite manner so that the pressure medium does not penetrate into the interface between the outer covering material and the core material. The billet has a passage inside the billet that communicates with the interface with the composite billet and is open to the atmosphere at the front end surface of the composite billet, and the thermal expansion coefficient of the outer jacket material is smaller than that of the core material, and The outer covering material and the core material are molded under conditions such that the gap between the outer covering material and the core material becomes substantially zero at the end of heating. Hereinafter, embodiments of the present invention will be described in detail based on the drawings. What is shown in FIG. 2 is an example of the composite billet 5 according to the present invention, in which the core material 6 is completely covered with the outer cover material 7 in FIG.
In this example, a part of the outer periphery of a core material 6 is covered with an outer covering material 7. The front end portions of these composite billets 5 are formed into a tapered shape. A slight gap 8 exists at the interface between the core material 6 and the outer covering material 7 of the composite billet 5 due to manufacturing errors and the like. This gap 8 is
It is completely sealed against the pressure medium so that the pressure medium, which will be explained next, does not enter during extrusion molding. However, the gap 8 communicates with an opening 9 provided approximately at the center of the front end surface of the composite billet 5 via a ventilation hole 10 or a ventilation groove 11. The ventilation hole 10 passes through the interior of the core material 6 and communicates with the opening 9, and the ventilation groove 11 is recessed in the outer circumference of the core material 6 and communicates with the opening 9. Both the ventilation hole 10 and the ventilation groove 11 communicate with the gap 8 at the front of the gap 8. Thus, the air within the gap 8 is in communication with the atmosphere. To extrude a composite material using the composite billet 5, a high temperature isostatic extrusion press 12 shown in FIG. 3 is used. 13 is a die, 14 is a container, 15 is a hydrostatic piston, and 16 is a pressure medium. The composite billet 5 is housed in a container 14 so that the opening 9 side of its front end face faces the die 13, and is pressed by a hydrostatic piston 15 from the rear side of the composite billet 5 via a pressure medium 16, and is released from the die hole 17. The composite material 18 is extruded. Before being stored in the container 14, the composite billet 5 is heated to a predetermined temperature. At this time, the outer diameter d ₁ of the core material 6, the coefficient of thermal expansion a ₁ , the inner diameter d ₂ of the outer covering material 7,
If the coefficient of thermal expansion is a ₂ , and the temperature is raised from T ₀ to T°C, and the gap 8 between the outer cover material 7 and the core material 6 is Δh, then Δh=d ₂ a ₂ (T-T ₀ ) −d ₁ a ₁ (T−T ₀ )=(d ₂ a ₂ −d ₁ a ₁ )(T−T ₀ ). Therefore, the coefficient of thermal expansion a ₁ of the core material 6 is the same as that of the outer covering material 7.
If a is larger than ₂ , Δh depends on the heating temperature.
may become negative. For example, in composite materials such as titanium-clad copper rods and Ni-clad copper rods that are used as corrosion-resistant electrode rods, as shown in Table ₁ , the thermal expansion coefficient of copper, which is the core material 6, is Since the coefficient of thermal expansion a ₂ of the material 7 is smaller, the state of Δh≦0 can be easily obtained.

[Table] Therefore, if the heating temperature during extrusion can be set in advance, the gap 8 at the time of fitting can be set so that Δh is zero or negative, taking into consideration the coefficient of thermal expansion, and the heating temperature can be set in advance. Meanwhile, the air in the gap 8 passes through the ventilation groove 11 or the ventilation hole 10 and is discharged from the opening 9, so that extrusion can be carried out soundly. Since the opening 9 and the ventilation hole 10 are provided at the front end of the composite billet 5, if the billet 5 is heated with a taper so that the rear end side is slightly higher, exhaust will be carried out more smoothly, and the temperature at the time of extrusion will be lowered. It is also possible to reduce the pressure increase due to the drop. As mentioned above, most of the air in the gap 8 is exhausted during heating, but if Δh does not become negative even during the heating and a gap still exists,
Alternatively, if a gap occurs due to a temperature drop during extrusion, the air in the gap 8 is discharged to the outside due to the deformation of the jacket material 7 due to the pressure increase during extrusion. That is, since the pressure gradient at the time of pressure increase increases toward the rear of the composite billet 5, the deformation of the jacket material 7 due to pressure progresses from the rear toward the front. Therefore, the gap 8 is crushed from the rear side, and the interface between the outer covering material 7 and the core material 6 is brought into close contact with each other toward the front. Since the ventilation hole 10 and the ventilation groove 11 are provided in the front part of the gap 8, the air in the gap 8 is completely exhausted due to the close contact of the interface. After being completely evacuated, the pressure increases further and the composite billet 5 is finally extruded from the die hole 17. Next, hot isostatic extrusion of a titanium clad copper rod was actually carried out using the composite billet according to the present invention and a conventional composite billet, and the results are shown in Table 2 for comparison. (1) The conventional billet shown in Figure 1 and Figure 2 a, with a pure copper core diameter of 62.0 ^{±0.03 mm} and a length of 200 mm, and an outer sheath material of 68.0 ^{± 0.05} mm and an inner diameter of 62.0〓〓mm.
The billet according to the present invention shown in Fig. 1 was created. (2) The billet heating temperature was 600°C, 700°C, and 800°C, the die angle 2a = 60°, and the extrusion ratio was 14.

[Table] As described above, according to the present invention, since the air between the interfaces is exhausted during heating, oxidation does not occur, a healthy product can be extruded over a wide temperature range, and there is little variation in adhesive strength. , it is possible to obtain a high-quality composite material with increased strength.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional composite billet, FIG. 2 is a sectional view showing an embodiment of the present invention, and FIG. 3 is a sectional view of a hot hydraulic extrusion press. 5... Composite billet, 6... Core material, 7... Outer covering material, 8... Gap, 9... Opening, 10... Ventilation hole, 11... Ventilation groove.

Claims (1)

[Scope of utility model registration request] A composite billet for high-temperature isostatic extrusion, in which an outer covering material and a core material are integrated into a composite body so that pressure medium does not enter the interface thereof, the billet is connected to the interface between the outer covering material and the core material, and the composite billet is connected to the interface between the outer covering material and the core material. The billet has a passage inside the billet that is open to the atmosphere at the front end surface, and the coefficient of thermal expansion of the outer covering material is smaller than that of the core material, and the outer covering material and the core are bonded together at the end of heating before extrusion molding. A composite billet for high-temperature isostatic extrusion, characterized in that an outer cover material and a core material are formed under conditions such that the gap between the material and the material is substantially zero.