JPS58171505A - Production of metallic tube having high melting point - Google Patents

Abstract

PURPOSE:To obtain a fine metallic tube having high m.p. which is dense and is provided with the characteristics suited for application such as protection tube or the like for high temp. in the stage of forging said tube through inserting a core into a blank tube produced by sintering a cylindrical molding of metallic powder having high m.p. by making the core of a superplastic material. CONSTITUTION:A prescribed vessel contg. Mo powder around a bar-like core made of mild steel is press molded with, for example, a hydrostatic press to obtain a cylindrical body. The core is removed from the molding removed from the press and the molding is heated and calcined in a calcining furnace, whereby a fine blank tube of Mo is obtained. A fine bar-like body consisting of a superplastic material, for example, a Ti alloy contg. 6% Al and 4% V is inserted as a core 1 into the hollow part of the tube 3. Both end parts 2 of the core 1 are projected from the respective end parts of the tube 3. The blank tube which is held inserted with the core in such a way is forged to form a fine tube of a prescribed size, and if the tube in this state is heated to about 950 deg.C, the core can be elongated easily; therefore, if the core is pulled in both ways, the core is reduced in size and can be pulled off from the fine Mo tube. Since the heating temp. in this state is low, the recrystallization of the Mo does not arise, and the fine Mo tube having dense quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a thin tube made of ai6M point metal.

[Technical background of the invention and its problems]

For example, a thin tube made of a high melting point metal such as molybdenum
It is used in the field of lumberjacks, such as for storing thermocouples of abused sheathed heaters. Formation of such a capillary is generally carried out as follows. A tube of, for example, 20 x 16 and 2001 m in length is formed using molybdenum powder. A core made of, for example, mild steel is placed in the center, and the molybdenum powder is placed in a tube surrounded by M1 and pressurized. A cylindrical molded body is obtained. After removing the core from this molded body, it is placed in a firing furnace and heated and sintered at 1800° C. for 3 to 8 hours to obtain a tube-shaped raw pipe. Since this material is a thin tube formed by powder metallurgy, it still has many pores, and its characteristics are not yet sufficient for use in the various applications mentioned above. For this reason, a thin copper rod, for example, is inserted as a core into the hollow part of this product, and then forged processing is performed to reduce the void area and form a thinner tube with predetermined dimensions. It is then inserted and heated to remove the nine core, and the core is removed to obtain a thin tube.

However, when removing the core in this way, when the core is made of copper as described above, approximately 1000
There is a membership fee to heat it up to 1200℃.

As a result, the molybdenum forming the tubule recrystallizes, making the molybdenum tubule brittle, which poses a problem in that it is difficult to use the tubule as a protective tube, for example.

[Purpose of the invention]

The present invention is based on these points and provides a method for manufacturing thin tubes made of a high-melting point metal such as molybdenum, which is dense and has characteristics suitable for use as high-temperature storage. The purpose is to

[Summary of the invention]

The high melting point metal powder is pressurized and molded into a cylindrical molded body using a hydrostatic press so that a sintered body having a predetermined size is obtained by sintering, and this is sintered. Next, when this tubular sintered body is forged to form a thin tube of a predetermined size, a core made of a superplastic material is inserted into the hollow part of the sintered body and forged, and after the forging process is completed, it is heated. The core is removed to form a thin tube made of a predetermined high melting point metal. By the method of this invention) good performance O having a thin and extremely small dense composition
^ Melting point gold 14 It is characterized by the ability to form thin tubes extremely efficiently.

[Embodiments of the invention]

The implementation of this invention will be explained below. Using molybdenum powder, press into a hydrostatic press machine (outer diameter) 14.
A tubular molded body with (inner diameter) 12# (length) 240 mm is molded. In other words, a rod-shaped body made of mild steel is used as the core,
K molybdenum powder is inserted around it, the nine predetermined containers are mounted on a hydrostatic press equipment, and a pressure of about 2 ton/cd is applied to perform pressure molding. In this way, pressure is applied uniformly over the entire area to obtain a round body. Next, the core was extracted from the molded body taken out from the press machine.10. It is placed in a firing furnace and heated at 1800° C. for 7 hours to sinter and obtain a desired molybdenum thin tube. The dimensions of this raw pipe are (outer diameter) 1
2. (Inner diameter)8. (Length) 200 kakus.

Next, a thin rod-shaped body (diameter 7.9 wm) made of 6@hl, 4*V-containing primary titanium alloy is inserted as a core into the hollow part of the wood pipe. The core inserted into the raw pipe is shaped so that both ends (2) of the core (1) protrude from the end faces of the woodwind (3), as shown in FIG.

In this way, the raw tube with the core inserted is forged to a specified size (outer diameter)7. (Inner a) Form a tubule of St (length) 650 orchid.

When the thin tube in this state is heated to 950@e, the core becomes K so that it can be easily stretched, so the core is drawn out from the molybdenum thin tube by drawing it in both directions to obtain a predetermined molybdenum thin tube.

In this way, when forming a thin tube using the method of the present invention, the heating temperature is low in order to pull out the core, so troublesome phenomena such as recrystallization of molybdenum do not occur, and molybdenum thin tubes made of dense material do not occur. is obtained, and the core inserted into the hollow part of the narrow tube can be pulled out very easily after the forging process is completed. In this way, a thin tube of a predetermined size can be formed efficiently without any loss in properties.

Therefore, thin tubes made of high melting point metals such as molybdenum can be used for applications such as P5LI-equipped storage tubes and exhibit excellent effects.

Although the description has been made regarding Tomo core using a titanium alloy containing 6% An and 4*V as the superplastic material, the present invention is not limited thereto, and other superplastic materials, such as 15Co, may be used.

It goes without saying that the same effect can be obtained by using 45 Ti, 5.5 Al, 3 Mo, N1 alloy, etc. as the core.

〔Effect of the invention〕

When removing the core inserted into the hollow part after the final forging process in manufacturing high melting point metal tubes such as molybdenum, this invention uses a core made of a superplastic material with low superacidity. Therefore, the core can be removed without causing any negative effects such as formation of noble crystals in the high melting point metal, and a high melting point metal thin tube with good characteristics can be efficiently obtained.

Although the above description has been made regarding the molybdenum capillary, it goes without saying that the present invention is not limited to this and can be applied to other melting point metal capillaries.

[Brief explanation of drawings]

FIG. 1 is a front view of a nine element tube into which a core of the present invention is inserted. 1... Core, 2... Both ends of the core, 3... Flat single point metal tube. Agent Patent Attorney Inoue - Male Figure 1

Claims (3)

[Claims] (1) High melting point metal powder is formed into a cylindrical body, then sintered, a core made of a superplastic material is inserted into a base tube, the core is forged, and the core is then removed. Method for manufacturing melting point metal tubes. (2) The method for manufacturing a high-melting point metal tube according to claim 1, wherein the core inserted into the raw tube is made of a titanium alloy containing 6 ml of Al and 4% V. (3) The method for manufacturing a high-melting point metal tube according to claim 1, characterized in that the high-melting point metal powder is formed into a cylindrical body by hydrostatic pressing.