Chatter Stability Analysis And Reliability Robust Optimization Design Of Machining System

Cutting chatter is strong self-excited vibration in metal-cutting process.The occurrence of chatter seriously reduces the machining accuracy and working efficiency.Taken turning and milling machining system as the study object,this paper establishes regenerative chatter model,analyses the cutting system's stability and studies how the machining system stability is influenced by system characteristic parameters.Considering the influence of random uncertainty,this paper researches machining reliability and reliability sensitivity.And then cutting system reliability optimization and robust design are accomplished.Main tasks are the following:Firstly,this paper establishes the cutting system dynamic model,draws out the stability lobes.According to this,the minimum cutting depth limit can be predicted.Thus the chatter's occurrence can be effectively prevented.Then the cutting parameters affecting cutting stability are discussed in detail.And this influence laws provide theoretical support for the selection of technological parameter.Secondly,considering the influence of random factors,this paper puts forward a chatter stability reliability calculation method in the process of cutting.By Monte Carlo method,acquiring the dynamic characteristics parameters samples of cutting system and through the dynamic model of regenerative chatter to calculate,the samples of limit cutting depth are gotten.Through studying the system chatter stability reliability problems,this paper provides the quantitative standard to avoid cutting chatter system occurring for the selection of cutting parameter under different processing conditions.Then,studying the cutting system characteristic parameters' reliability sensitivity,some reasonable suggestions are proposed concerning the measurement of characteristic parameters and the accuracy of machine tool manufacturing.For high influence factors,their error range would be strictly controlled and their actual values would be close to design sizes.For low influence factors,the size can be placed by the design tolerance range to reduce machining costs.Finally,by taking the actual cutting system parameters as constraint condition,setting up the maximum cutting system stability reliability as the goal,the system reliability increases significantly through the optimization design.And based on the sensitivity of system,taken the minimum system parameter sensitivity values' square sum as design goal,the purpose of the system being more robust is achieved through robust design.