切深对椭圆超声振动切削机理的影响

以椭圆超声振动切削为研究对象,通过理论分析,有限元仿真和切削实验,研究了切深变量对其切削过程中机理的影响。指出在微小的切深条件下,刀尖钝圆影响不可忽略,其切削过程表现出微细切削特性。一方面,基于微细切削理论,建立了正交椭圆超声振动切削运动学和力学模型,将切削区分为后刀面回弹区、刀尖犁切区、刀尖剪切区和前刀面摩擦区四个区域,并依次对四个区域内不同切深条件下各个切削分力进行计算分析。另一方面,对切削过程进行有限元仿真和切削实验。其结果表明:当切深小于最小切削厚度时,切削过程主要为刀具后刀面的回弹挤压与摩擦和刀尖钝圆的犁切作用,不产生切屑,切深抗力大于主切削力;当切深大于最小切削厚度并逐渐增大时,刀尖剪切和切屑与前刀面的挤压与摩擦作用逐渐凸显并成为主要切削方式,此时主切削力逐渐超过切深抗力并迅速增大。

Influence of depth of cut on elliptical ultrasonic vibration cutting mechanism

The influence of the depth of cut on the elliptical ultrasonic vibration cutting mechanism is analyzed through theoretical model,finite element simulation and cutting experiment.It is found that when the depth of cut is small,the influence of the rounded cutting edge must be taken into consideration,and the cutting process reveals the micro-machining characteristics.The kinematics model and dynamics model for orthogonal elliptical ultrasonic vibration cutting are established based on the micro-machining theory.In the proposed models,the cutting tool is firstly divided into four cutting zones:the elastic recovery zone on the flank face,the ploughing zone on the rounded cutting edge,the shearing zone on the rounded cutting edge,and tool-chip friction zone on the rake face.The cutting force in each zone is then calculated.Finite element simulations of the cutting process and cutting experiments are also conducted.Simulation results show that when the depth of cut is less than the minimum cutting thickness,the cutting process is dominated by elastic recovery and friction on the flank face and ploughing of the rounded cutting edge,without chip generation,with the thrust cutting force being greater than the principal cutting force.However,when the depth of cut exceeds the minimum cutting thickness and keeps increasing,the effects of rounded cutting edge shearing and tool-chip friction on the rake face gradually take the dominant place during the cutting process,while the principal cutting force exceeds the thrust cutting force and increases rapidly.