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Method for producing tungsten bar for calendering

A production method and technology of tungsten bars, applied in other manufacturing equipment/tools, mechanical equipment, turbines, etc., can solve the problems of reduced product yield, uneven pressure, splitting, etc., to avoid edge and corner drop of the green compact , Uniform density, consistent shrinkage and deformation

Inactive Publication Date: 2011-06-22
ZHUZHOU HARD ALLOY GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are many inherent disadvantages in the production of the "steel mold pressing-vertical melting sintering" process: (1) The pressure of each part of the billet pressed by the steel mold is not uniform, and it is very easy to produce cracks, edges and corners and other defects, resulting in product The actual yield is reduced; (2) During vertical melting and sintering, the low current density at the chuck position leads to low sintering temperature, resulting in low density at both ends of the product, which must be cut off before use. This part of the material loss also reduces the actual yield of the product; (3) The performance of each part of the vertical melting rod is not uniform, and it is easy to cause quality problems such as skinning and splitting when processing and forming bars; (4) Vertical melting and sintering uses direct heating of the billet to make it reach Very high temperature sintering dense process, very high energy consumption

Method used

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  • Method for producing tungsten bar for calendering
  • Method for producing tungsten bar for calendering
  • Method for producing tungsten bar for calendering

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] Example 1: Prepare 100 tungsten rods with a unit weight of 1.26kg and a size of Ф16.5mm×315mm with cerium added.

[0014] Put 1.26kg of tungsten powder added with cerium into a cylindrical soft mold with an inner diameter of Ф22mm×465mm and seal it. Prepare 100 blanks as above, put them in the cold isostatic pressing cylinder at the same time, pressurize to 200Mpa, hold the pressure for 5 minutes, and complete the cold isostatic pressing after 2 minutes of linear pressure relief, unload the mold, and obtain a size of Ф19. 100 compacts of 5mm×370mm.

[0015] 100 compacts were put into the intermediate frequency sintering furnace, and hydrogen gas was introduced. According to the sintering process (see Table 1), the temperature was gradually raised and kept warm until the final sintering temperature of 2400°C was reached and then kept for 8 hours. Then the temperature is lowered and taken out to obtain a rod-shaped sintered blank.

[0016] Put the sintered blank in a he...

Embodiment 2

[0019] Example 2: Prepare 100 tungsten rods with a unit weight of 1.50 kg and a size of Ф16.5 mm×335 mm with addition of cerium element.

[0020] Put 1.50kg of tungsten powder added with cerium into a cylindrical soft mold with an inner diameter of Ф22mm×503mm and seal it. Prepare 100 blanks as above, put them in the cold isostatic pressing cylinder at the same time, pressurize to 220Mpa, hold the pressure for 0.5 minutes, and complete the cold isostatic pressing after 10 minutes of linear pressure relief, unload the mold, and obtain a size of Ф19. 5mm×395mm compact.

[0021] 100 compacts were put into a high-frequency sintering furnace, and nitrogen gas was introduced. According to the sintering process (see Table 1), the temperature was gradually raised and kept warm until the final sintering temperature of 2300°C was reached and then kept warm for 15 hours. Then the temperature is lowered and taken out to obtain a rod-shaped sintered blank.

[0022] Put the sintered blank...

Embodiment 3

[0023] Example 3: Prepare 100 tungsten bars with a unit weight of 1.35kg and a size of Ф16.5mm×325mm with cerium added.

[0024] Put 1.35kg of tungsten powder added with cerium into a Ф22mm×475mm cylindrical soft mold and seal it. Prepare 100 blanks as above, put them in the cold isostatic pressing cylinder at the same time, pressurize to 180Mpa, hold the pressure for 10 minutes, and complete the cold isostatic pressing and unloading the mold after 0.5 minutes of linear pressure relief, and the obtained size is Ф19.5mm ×385mm compact.

[0025] Put 100 compacts into the intermediate frequency sintering furnace, vacuumize, and gradually heat up and keep warm according to the sintering process (see Table 1). After reaching the final sintering temperature of 2220°C, keep warm for 2 hours. See the notes in Table 1 for the hydrogen flow at each stage. Then the temperature is lowered to obtain a rod-shaped sintered blank.

[0026] Put the sintered blank in a heating furnace with hy...

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Abstract

The invention discloses a new method for producing a tungsten bar for calendaring. The method sequentially comprises the following steps of: moulding prepared tungsten powder and performing cold isostatic pressing; sintering pressed billets at the temperature of between 2,150 and 2,500 by using a heating furnace under vacuum or protective atmosphere; preserving the heat for 2 to 15 hours to obtain the sintered billets; placing the sintered billets into the heating furnace at the temperature of between 1,000 and 1,400 DEG C and under the protective atmosphere to heat for 15 to 50 minutes; taking out the sintered billets; and straightening the sintered billets to obtain the final tungsten bar product. By the method, crack-generating, edge-losing and corner-losing phenomena of the product are avoided; density of the product is uniform; the internal quality of the product is improved; the product is not required to be subjected to heat cutting or low-temperature sintering or be processed; the actual yield of the products is greatly improved; and energy consumption is greatly reduced.

Description

technical field [0001] The invention relates to a production method for preparing tungsten bars for rolling. Background technique [0002] Now the production of tungsten rods for heating resistor tungsten wire and filament tungsten support frame, tungsten rod for electrode, tungsten hinge wire and other products generally adopts the process route of "steel mold pressing-vertical melting and sintering". There are pure tungsten billets, doped billets with rare earth elements or silicon, aluminum, potassium and other elements added. However, there are many inherent disadvantages in the production of the "steel mold pressing-vertical melting sintering" process: (1) The pressure of each part of the billet pressed by the steel mold is not uniform, and it is very easy to produce cracks, edges and corners and other defects, resulting in product The actual yield is reduced; (2) During vertical melting and sintering, the low current density at the chuck position leads to low sinterin...

Claims

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Application Information

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IPC IPC(8): B22F3/16B22F3/04B22F3/03B22F5/00
Inventor 杨世民李春兰向卫东梅文俊姜明傅崇伟曾建辉李鹏
Owner ZHUZHOU HARD ALLOY GRP CO LTD
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