【摘要】 对微细电火花沉积加工中沉积所得不同微细结构的成形机理进行了研究.在电火花成形机床上,通过合理选择工艺参数,用黄铜电极在高速钢工件表面稳定沉积出外径约0.20mm、线径约0.09mm的微螺旋结构和直径约0.20mm微圆柱体.通过有限元法对工具电极放电点的瞬态温度场进行了模拟,分析结果表明,不同的放电能量密度影响材料的蚀除形式,继而影响蚀除电极材料在放电通道中的运动,最终影响微细结构的成形过程.对沉积材料微观组织结构分析表明,沉积材料与基体结合层为冶金结合方式,结合紧密,并由于凝固过程极大的冷却速率,使沉积材料在凝固过程中发生了晶粒细化现象.更多还原

【Abstract】 The forming mechanism of different micro structures fabricated by micro electrical discharge machining (EDM) deposition was studied. On EDM shaping machine, with brass as tool electrode, micro spiral structures with 0.20 mm in external diameter, 0.09 mm in wire diameter and micro cylinders with 0.20 mm in diameter were deposited steadily on high-speed steel surface with proper conditions. The transient temperature field on the discharge point of the tool electrode was simulated. The results show that different discharge energy densities have impact on the removal form of tool electrode material, and then on the movement of removed material and the formation process of micro structures. The bonding behavior between the deposit and the base was analyzed and the deposit microstructure was also observed, which showed that there was strong metallurgical bonding between the both, and the grain size of the deposit refined because of the high cooling rate of the solidification process.更多还原