Manufacturing Details of Fine Tungsten Wire

Tungsten filament has excellent heat resistance and mechanical strength, so as cathode filament of TV electronic gun and filament material of various electrode materials, automobile lamp, lighting lamp of household appliances and photocopier lamp, it is widely used in many forms.

In order not to break the tungsten wire, the traditional method of drawing tungsten wire can draw smoothly and coat lubricant on the surface of tungsten material. In this case, the high melting point metal, tungsten wire, is heated at about 1200 C for wire drawing, so carbon lubricant with good heat resistance is used as lubricant. The carbon lubricant is prepared by dissolving graphite powder with water and then adding a thickener.

As a filament material, tungsten filament, which emits light at high temperature after electrification and is used in high vibration environment, requires high temperature resistance and vibration resistance, namely the so-called anti-droop function. However, tungsten wires manufactured by previous methods are prone to fluctuation of product properties caused by uneven wire diameter or reduction of product yield due to cracks. Therefore, further technical improvement of product quality is required.

Some enterprises adopt a method to improve the yield and quality of tungsten wire by a large margin. The main contents are as follows:

1.Tungsten powder is formed by die. After pre-sintering at 1400 ~℃, tungsten sinter is prepared by electro-sintering in hydrogen flow at the highest temperature of 3000 ~℃.

2.Then, the obtained tungsten sintered body is processed by rotary forging and recrystallization to prepare tungsten wire with a diameter of 1.0 mm. Using the tungsten wire, the wire drawing process is carried out under the conditions of wire temperature: 900 ℃, drawing die temperature: 500 ℃ and drawing speed: 50m/min.

3.By annealing the tungsten wire at a linear speed of 30 m/min, which can be heated to a superheated area of 100 mm at 1000 ℃, the final target diameter of the wire can be obtained, and the lubricant with a specific gravity of 1.05 g/cm³ is used.

Among them, the method of evaluating the number of crack occurrence points is winding the wire at a constant speed (120m/min), and counting the number of signals detected by the through eddy current flaw detector according to the determination conditions set by each wire diameter as the number of crack occurrence points. The number of cracks above 100 is unqualified.

Because the section shrinkage of tungsten wire material in final drawing process is stipulated in the predetermined range, the deviation of wire breakage or wire diameter caused by cracks in tungsten wire can be greatly reduced, the yield of tungsten wire can be greatly increased, and the quality of products can be greatly improved. In the process of fabricating tungsten wire with final diameter of 0.05 mm to 1.10 mm, finishing is carried out so that the section shrinkage of tungsten material can reach 5%-15% in the process of wire finishing.

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