Vibration Characteristics Of The Cutting Tool System With Weak Rigid Shim And Its Effects On Impact Damage Of The Cutting Tool

In the tool system,the bottom of the tool is often equipped with a shim to protect the cutter body and determine the tool position which is required with material of hardness not less than 55 HRC because a shim with high hardness and high rigidity is conducive to maintaining the position of the tool and ensuring the machining accuracy.However,the high-rigidity shim counts against the impact stress buffer and reduce the peak stress of the tool impact response of the tool-shim contact surface,making it not suitable in the rough machining stage when high machining accuracy is not required but long tool life and high cutting efficiency are required.By establishing the forced vibration model of the tool-shim with different stiffness,the impact and stress vibration response characteristics of tool-shim system is analyzed,the influence of inertia of weak rigid tool-shim system in high speed cutting on impact damage of tool is explored,and the influence of shim stiffness on low stress impact of tool is studied to provide reference for tool optimization design and improving tool cutting performance.The main research contents of this thesis are as follows:Firstly,a tool-shim system vibration model is established to analyze the impact loading response characteristics of different stiffness tools,including analyzing the dynamic response balance between tool inertial force,shim elastic reaction force,and damping force,as well as the influence of tool-shim stiffness on the loading rate,peak value,high-level fluctuation,unloading rate,and elastic energy release.Meanwhile,a theoretical analysis is carried out on the stress field change near the tool crack tip and the experiment of discontinuous cutting with four kinds of carbide shims,that is,the N8 aluminum alloy,the TC4 titanium alloy,the 08 steel and the YT14 cemented carbide is performed at the end.The analysis on each stage of the vibration response is verified and the influence of different stiffness shims on the initial loading rate,peak,high fluctuation amplitude,unloading rate,peak cutting force in the residual response stage and the morphology of tool grinding damage are analyzed.Secondly,the dynamic of the tool-shim system in the range of low frequency and high speed is explored and the particularity of transient inertial in the response of high speed vibration in tool-shim system is discussed.The simulation model of the impact problem is established under the tool with different stiffness and the theoretical analysis and simulation results are verified by high-speed cutting experiment at the end.Finally,under the cutting parameters of spindle speed of 900 r/min,0.2 mm on back engagement of the cutting edge and feed amount of 0.175 mm/r,the intermittent cutting length is increased to calculate the cutting length.The influence of weak rigid shim on tool fatigue damage under high cutting speed and small cutting parameters is studied.The cutting force and acceleration collected in the fatigue experiment are analyzed,and the influence of the weak rigid shim on the high fluctuation amplitude of the cutting force and the peak value of the cutting force and the amplitude of the acceleration fluctuation are studied.The development process of tool fatigue damage of weak rigid shim is analyzed.The fatigue damage size of the rake face and the flank face of the tool with different stiffness shims is statistically analyzed,and the influence of the inertia of the tool system on the change range of the fatigue damage size of the tool rake face is explored.The tool fatigue damage form and fatigue life of different stiffness shims are studied.