Influence of arc discharge to the contact strip of carbon-carbon composites was orthogonally studied on the HST-100 tribo-tester under electric current, which simulated working conditions of the pantograph-wire system used in electric railway. The regression equation between specific wear rate and arc discharge were obtained and analyzed through the non-linear regression and orthogonal design. The results of the experiments show that a power function between specific wear rate and arc discharge was obtained. Microstructure and phase composition were observed and analyzed by scanning electron microscope(SEM), energy dispersive X-ray spectrum(EDS) and temperature sensor. The results revealed that the arc discharge dissipation seriously affects tribological characteristics of the carboncarbon composites. The temperature of some local contact points beyond their melting point with the electric arc heat effect, and give rise to the desposite carbon and friber carbon were vaporazated, which form the lubrication film on the wear surface, and with the augmant of the arc discharge, the area of lubrication film of carbon was decrease. Therefore, the main wear form of the arc erosion of the carbon-carbon composites is evaporate erosion and material transfer.
This paper analyzes the forming process methods of cam in CPU socket to control its open and close. The whole process is pierce, notch, the first forging forming, the second pierce(the second pilot hole), the second forging forming(sizing), impact forging forming, and trimming. The punch shape design of the first forging forming is simulated by finite element analysis. The optimized punch profile radius 0.50mm and punch size Φ10.60mm are available. Cold forging of precision progressive die is put forward. The second pierce pilot hole that newly designed is applied, which relief the deformation of pilot holes caused by severe metal flow. Compared with the traditional single operation dies, the precision progressive die based on cold forging process were proved through the practical production to be high economical efficiency, which could be the references for developing the cold forging process of producing the similar produsts.
The objective of this study was to research a newly progressive die , which unifies the merit of high efficiency of the progressive dies and the high material-using ratio of the project dies. This paper analyzes the forming process methods of IHS(Intel Heat Spreader), and develop a set of progressive die with transfer unit , which turns project die to progressive die. The cooperation between the transfer unit and the die was studied, and the key technology of the newly progressive dies were investigated. Compared with the traditional die, the mechanization and electrization are realized to increase the production efficiency and get highly precise IHS. The newly designed transfer unit is expected to be a helpful reference for designers facing demands for higher quality, lower cost and shorter delivery time for some special products.
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