300M钢超声滚压表面形貌演变机理和试验表征

Mechanism and Experimental Characterization of Surface Morphology Evolution of 300M Steel during Ultrasonic Rolling Process

基于超声滚压过程中的接触力学理论,提出了单位面积冲击接触率评价指标,求解了不同工艺参数下接触中心位移和接触区域面积。研究了超声滚压过程中表面形貌光整加工机理,提出了表面层材料主动塑性变形区、被动塑性变形区和被动弹性变形区的特征结构。通过正交试验探讨超声滚压参数对表面粗糙度的作用规律,为通过优化超声滚压参数从而实现表面形貌主动控制提供理论依据。结果表明,在选取的超声滚压工艺参数下,滚压球与工件接触中心的位移值总是大于超声振幅值,这表明超声滚压过程中滚压头始终与工件表面保持接触。超声滚压具有“削峰填谷”效应,表面主动塑性变形区材料流动是引起表面光洁度提升的根本原因。滚压球进给速度对表面粗糙度的影响最大,静载荷次之,转速最小。在超声滚压过程中如果想要实现较好的表面光洁度同时提高加工效率,可选取较高的转速、较大的静载荷和较小的滚压球进给。

Based on the contact mechanics theory in ultrasonic rolling process,the evaluation index of impact contact rate per unit area is proposed,and the displacement and area of ball-workpiece contact under different process parameters are solved.The mechanism of surface finishing in ultrasonic rolling process is studied,and the featured structures of active plastic deformation zone,passive plastic deformation zone and passive elastic deformation zone of surface layer materials are proposed.The effect of ultrasonic rolling parameters on surface roughness is discussed through orthogonal test,which provides a theoretical basis for the active control of surface topography by optimizing ultrasonic rolling parameters.The results show that the displacement value of the contact point between the rolling ball and the workpiece is always higher than the ultrasonic amplitude value under the ultrasonic rolling process parameters selected,which indicates that the rolling head always keeps in contact with the workpiece surface during the ultrasonic rolling process.Ultrasonic rolling has the effect of“peak shaving and filling valley”,and the material flow in the active plastic deformation area of the surface is the fundamental reason for the improvement of surface finish.The feed speed of the rolling ball has the greatest influence on the surface roughness,followed by the static load and the minimum speed.If a better surface finish and higher machining efficiency are desired during the ultrasonic rolling process,higher speed,larger static load and smaller ball feed can be selected.