The final heat treatment of the final heat treatment is aging treatment to ensure good comprehensive mechanical properties and elastic and plastic fit. The aging treatment was carried out in a 45 kW box furnace, and the welded spring was placed horizontally in a metal box and buried with 74 Lm of fine quartz sand. The heat treatment process and mechanical properties are based on the service conditions and failure modes of the finger, and the specific heat treatment process and performance are shown. This is because, after quenching pretreatment, the material structure is single-phase A phase, and no cold deformation, ie work hardening, is performed before aging; when the aging temperature increases, the tensile strength increases first and then decreases, at 335e (No. 4 Sample) appears a peak. Since the random finger samples of foreign companies do not provide various performance parameters, they cannot be tested for performance (the tensile test cannot be performed after the wire is wound). The only reference data is that its service life is about 10,000 times.
The cracking of the weld seam of the spring finger is the main reason for the early failure of the finger. The welding strength should be increased as much as possible to ensure the weld is full, no leakage welding, and virtual welding. The welding contact area of ​​the spring is small, the operating space during welding is only about 210 mm, the base material itself is relatively brittle, and the thermal conductivity is good, and it is difficult to weld, and special solder and jig must be used. According to the actual situation of the factory, the ON-1A welding machine is used for spot welding. The welding process parameters are: visible, after the above process welding, the fracture part is in the welding heat affected zone, and the welding strength is close to the strength of the base metal.
The actual life test device of the installed life test spring finger is exactly the same as the internal structure of the circuit breaker. The test conditions are: the spring finger is fixed in a circular groove with a minimum inner diameter of <95mm, and the outer casing is in contact with a pressure cylinder having an inner diameter of <116mm. The spring contact ring has three points of contact in each single ring, the radial compression of the single ring exceeds 1mm; the moving speed of the pressure cylinder relative to the spring finger is 416418m/s; the working environment is high pressure sulfur hexafluoride gas, and the inflation pressure is 015MPa; Number of spring fingers: two groups (6 per group). Production and application At present, Ningbo Tianan Group Corporation has formed mass production of LW39-126/T3150-40 high-voltage AC porcelain column sulphur hexafluoride circuit breaker. The three-phase AC outdoor circuit breaker is suitable for 50Hz, 110kV power distribution system, plays a role of control and protection, and can also be used as a contact breaker. It is a key equipment for the operation of China's power system and has a large market. At the beginning of 2004, the company officially put into mass production, and the products were sold to all parts of the country. The output reached 205 units in the same year, and the output in 2005 was 379 units.
Conclusion After the aging treatment of QBe119 deformed beryllium bronze (3453)e@(115210)h, the tensile strength is 930MPa, which can meet the performance requirements of spring finger; its welding strength is 492MPa, and the resistance of the base metal The tensile strength is equivalent; after bending and forming, the geometric accuracy can meet the product design requirements. The spring finger is tested by the actual installed life, and the average service life is more than 10,000 times, reaching the level of similar foreign products, and the price is significantly reduced.
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