试验10 “圆环镦粗法”测定塑性变形摩擦系数(国外英文资料).docVIP

实验10 “圆环镦粗法”测定塑性变形摩擦系数(国外英文资料) The results show that the friction coefficient of plastic deformation is determined by the ring upsetting method One, the purpose of the experiment Study the method to determine the coefficient of plastic deformation by using a ring upsetting method. Understand the effect of friction coefficient on deformation resistance. Second, the experimental condition Laboratory equipment: 60T universal testing machine; Tools: two vianvil, the roughness of Ra 12.5 and Ra 0.8; Scale, vernier calipers. Material: aluminum alloy ring specimen 3, stearic acid zinc small. Third, the experimental principle Between flat anvil upsetting ring specimen, the metal flow of radial mainly depends on the friction condition on the surface of the specimen in contact with the tool, the plastic deformation of the friction condition can use mu friction coefficient and friction factor m, according to the following two relations: The friction of the surface of the rough surface is determined by the coulombs law before reaching the maximum shear stress. After achieving maximum shear stress tau Max, tau is determined by the maximum shear stress invariant: In the formula, tao k - shear yield stress of the material. When the entire contact surface friction stress reaches tau k, completely is no relative sliding contact with the specimen surface, at this time of the plastic deformation and friction coefficient or the maximum friction coefficient m, u = 0.577 namely, m = 1. The radial flow state of the metal varies depending on the conditions of friction. When m is very small, the radial flow of the metal is all outward, and the outer diameter of the ring is increased. When the m value is large, the outer metal outward, the inner metal to flow, increase, inner diameter of ring specimen diameter decreases, and at this time should have a thought that rho radius distribution layer. When the divergence layer rho is equal to the inner diameter of the ring, the corresponding frict