论文部分内容阅读
热挤压冲头服役时与约1000℃金属坯料接触时间较长,冲头表层温度急剧升至400～600℃,若冷却不及时将超过650℃,硬度降低,导致冲头软塌。金属坯料成型过程中冲头承受很大的挤压力,因金属塑性变形急烈流动与冲头强烈摩擦,导致热磨。冲头脱模时承受反挤压力,用水冷却,反复加热与冷却,冲头表层反复膨胀与收缩,因内层与外层胀缩不一致,形成热应力、机械应力,甚至出现组织应力,多种应力叠加导致热疲劳龟裂。因此,热冲头应有高的耐磨损抗力、变形抗力、断裂抗力、冲击抗力、软化抗力、疲劳抗力和热稳定性。笔者选用国家推广的4C_r5M_oV_lS_i新型热作模具钢,采用复合强化处理,热挤压冲头使用寿命比常规处理提高2～3倍,有显著的技术经济效益。
Hot extrusion punch service with about 1000 ℃ metal billets longer contact time, the punch surface temperature rose sharply to 400 ~ 600 ℃, if the cooling will not exceed 650 ℃, the hardness decreases, leading to punch soft collapse. Metal billet punch in the process of forming a lot of pressure, due to the metal plastic deformation of the violent flow and punch strong friction, resulting in hot mill. The punch is subjected to anti-extrusion pressure when it is demolded, cooled with water, repeated heating and cooling, repeated expansion and contraction of the punch surface, due to inconsistent expansion and contraction of the inner and outer layers to form thermal stress, mechanical stress and even tissue stress, and more Stress superposition leads to thermal fatigue cracking. Therefore, the hot punch should have high wear resistance, deformation resistance, fracture resistance, impact resistance, softening resistance, fatigue resistance and thermal stability. The author selected the national promotion of 4C_r5M_oV_lS_i new hot work die steel, the use of composite strengthening treatment, hot extrusion punch life than conventional treatment increased by 2 to 3 times, a significant technical and economic benefits.