超声振动辅助微挤压成形界面摩擦特性研究

Investigation on interfacial friction characteristics of ultrasonic vibration⁃assisted micro⁃extrusion forming

基于超声振动辅助微挤压成形过程摩擦特性表征需求,将超声振动辅助双杯挤压实验拆分为超声振动辅助正杯挤压和反杯挤压两个部分。通过超声振动辅助T2紫铜正杯挤压和反杯挤压的对比成形实验研究了不同超声振动模式辅助微挤压成形过程中试样-模具型腔间的界面摩擦特性,并提出一种量化评价新方法来评估超声振动辅助微挤压成形试样-模具型腔间摩擦应力及摩擦因数的变化规律。结果表明,微挤压成形应力降低值和试样-模具型腔间的摩擦应力降低值都随着超声振幅的增大而增大,且随着工具超声振动、工具-工件复合超声振动和工件超声振动的不同超声振动模式顺序依次增大。

Ultrasonic vibration⁃assisted double⁃cup extrusion experiments were divided into two parts:ultrasonic vibration⁃assisted forward cup extrusion and backward cup extrusion experiments,which was based on friction characterization requirements of ultrasonic vibration⁃assisted micro⁃extrusion forming process.The interfacial friction characteristics between sample and mold cavity during micro⁃extrusion process assisted by different ultrasonic vibration modes were studied by the comparative forming experiments of ultrasonic vibration⁃assisted forward cup extrusion and backward cup extrusion of copper T2.Furthermore,a new quantitative evaluation method was proposed to evalu⁃ate the change laws of the friction stress and the friction factor between sample and mold cavity in the ultrasonic vibration⁃assisted micro⁃extrusion process.The results show that both the reduction values of the micro⁃extrusion forming stress and the reduction values of friction stress between sample and mold cavity increase with the increase of ultrasonic amplitude,which also increase sequentially with the multi⁃ple ultrasonic vibration modes of tool ultrasonic vibration,tool⁃workpiece compound ultrasonic vibration and workpiece ultrasonic vibration.