Dynamic Modeling And Stability Analysis Of Micro-cutting Considering Process Damping

With the development of micro-miniaturization of products,micro-scale parts have become more and more widely used in biomedical and aerospace.A hotspot has been researched corresponding to the micro-cutting technology.During the machining process,chattering is an important factor restricting efficient micro-cutting,and the process damping effect during the cutting process can suppress the generation of chattering.In the low-speed cutting area,the effect of process damping on critical width of cut and system stability is particularly significant.Aiming at the problem of tool vibration,a micro-cutting dynamics model considering the influence of process damping is established.The stability lobes diagram is used to predict the stability of the micro-cutting process.The appropriate cutting conditions are selected for cutting.It is essential for the efficient cutting of materials that cannot be processed at high speeds,such as nickel-based alloys and titanium alloys.This article intends to take the process damping generated in the micro-cutting process as the research object.The main research work and conclusions are as follows:(1)Establishment of damping model in the micro-cutting process.Based on metal-cutting dynamics,a single-degree-of-freedom regenerative chatter micro-cutting machining dynamics model is established,and a nonlinear damping time-delay system is used to illustrate the dynamics in the machining process.For the well-established problem of self-excited vibrations in the machining,respectively,the micro-cutting dynamics model without considering process damping,the linear process damping micro-cutting dynamics model,the nonlinear process damping micro-cutting dynamics model,and the micro-cutting dynamics model considering vibration rippling were established.(2)Micro-cutting stability analysis of different process damping models.The parameters of the micro-cutting chatter stability model are subjected to a single variable,and its influence on the stability of the micro-cutting system is analyzed.In the micro-cutting chatter stability model without considering the process damping,the critical width of cut has a particularly significant effect on the system stability.In the linear process damping micro-cutting chatter stability model,the cutting edge radius is appropriately increased,the cutting force will increase,the area of the indentation area will also increase,and the process damping force will increase,the stability of the system will increase,and the stability area of the corresponding stability lobe pattern will increase.Similarly,appropriate increasing the tool clearance angle and separation angles will also affect the system stability.In the micro-cutting chatter stability model of nonlinear process damping,properly increasing the tool clearance angle will reduce the area of the interference area between the tool flank and the workpiece surface,and the friction force will also be reduced,so the process damping force will be reduced,the stability of the system is reduced,and the stability region of the corresponding stability lobe diagram is also reduced.Similarly,when the size of variables such as negative rake angle and limit cycle amplitude is changed,the stability of the system will also be affected.In the process damping micro-cutting chatter stability model affected by rippling,properly increasing the chatter frequency will result in an increase in the ripple slope,a shorter wavelength,and increased indentation area,a larger process damping coefficient,and an increased system stability.At the same time,the stability area of the corresponding stability lobe diagram also becomes larger.Similarly,changing the size of variables such as cutting speed and vibration amplitude will also affect the stability of the system.By comparing and analyzing the micro-cutting stability lobe diagrams of the above four different process damping models,it is found that in the low-speed cutting area,the stable cutting area of the stability lobe diagram considering the process damping effect is significantly larger than that without considering the process damping effect.When there are many factors that affect the process damping,it will increase the accuracy of the micro-cutting model.(3)Experimental verification of the chatter stability domain in micro-cutting.The chatter stability of the micro-cutting area point is judged by the change rule of the vibration time-domain signal and power spectrum diagram.The experimental results verify the correctness of the above micro-cutting models solution method and its stability analysis.