A 2 DOF dynamic model of regenerative chatter model with state-dependent time delay is developed in milling processes. Regenerative effects, ＂ploughing＂ or ＂rubbing＂ effects between the flank of the cutting edge a...A 2 DOF dynamic model of regenerative chatter model with state-dependent time delay is developed in milling processes. Regenerative effects, ＂ploughing＂ or ＂rubbing＂ effects between the flank of the cutting edge and the machined surface, and feed effects are considered. It is shown that the regenerative delay is determined by the combination of the cutter rotation and the tool vibrations resulting in a state-dependent time delay. The governing equation is a delay-differential equation with state-dependent delay （SD-DDE）, as op- posed to the standard models with constant time delay. Based on Frechet derivative theory, the linearization of periodic state-dependent delay differential equation is also investigated. For a system with practical milling parameters, the incorporation of the state-dependent delay into the model does not essentially affect the linear stability properties of the system.展开更多
Chatter in the machining system can result in a decrease in tool life,poor surface finish,conservative cutting parameters,etc.Despite many review papers promoting the understanding and research of this area,chatter su...Chatter in the machining system can result in a decrease in tool life,poor surface finish,conservative cutting parameters,etc.Despite many review papers promoting the understanding and research of this area,chatter suppression techniques are generally discussed within limited pages in the framework of comprehensive chatter-related problems.In recent years,the developments of smart materials,advanced sensing techniques,and more effective control strategies have led to some new progress in chatter suppression.Meanwhile,the widely used thin-walled parts present more and more severe machining challenges in their milling processes.Considering the above deficiencies,this paper summarizes the current state of the art in milling chatter suppression.New classifications of chatter suppression techniques are proposed according to the working principle and control target.Based on the new classified framework,the mechanism and comparisons of different chatter suppression strategies are reviewed.Besides,the current challenges and potential tendencies of milling chatter suppression techniques are highlighted.Intellectualization,integration,compactness,adaptability to workpiece geometry,and the collaboration of multiple control methods are predicted to be important trends in the future.展开更多
By turning a specifically designed conical part, complete process of metal cutting, in which the chatter occurs and expands, is recorded and analyzed. This process exposes that chatter vibration has two characters cal...By turning a specifically designed conical part, complete process of metal cutting, in which the chatter occurs and expands, is recorded and analyzed. This process exposes that chatter vibration has two characters called continuity and break. The continuity character means that vibration extent enlarges continuously while chatter frequency is almost changeless as the cutting depth extends downwards continuously. The break one is that chatter frequency moves rapidly downwards to a lower level while chatter remains after the cutting depth reach another given value. It is confirmed through an exciting test that the two chatter frequencies obtained in chatter test belong to the natural frequencies of workpiece system and cutting tool system respectively. From the viewpoints of chatter energy supplying and chatter mass effect, the. chatter should occur on one of the two final executive components in its natural frequency. On this basis, a new chatter model with two chatter active bodies is proposed. This new model can better explain the above phenomenon, and adapt to chatter monitoring and improvement of component structure well.展开更多
基金the National Natural Science Foundation of China (50435020,50705052,50575126)the Natural Science Foundation of Shandong Province (Y2007F41)
文摘A 2 DOF dynamic model of regenerative chatter model with state-dependent time delay is developed in milling processes. Regenerative effects, ＂ploughing＂ or ＂rubbing＂ effects between the flank of the cutting edge and the machined surface, and feed effects are considered. It is shown that the regenerative delay is determined by the combination of the cutter rotation and the tool vibrations resulting in a state-dependent time delay. The governing equation is a delay-differential equation with state-dependent delay （SD-DDE）, as op- posed to the standard models with constant time delay. Based on Frechet derivative theory, the linearization of periodic state-dependent delay differential equation is also investigated. For a system with practical milling parameters, the incorporation of the state-dependent delay into the model does not essentially affect the linear stability properties of the system.
基金co-supported by the National Natural Science Foundation of China(No.52275445)the Key Research and Development Plan of Shandong Province(Nos.2020CXGC010204,2023CXPT014,and 2021JMRH0301).
文摘Chatter in the machining system can result in a decrease in tool life,poor surface finish,conservative cutting parameters,etc.Despite many review papers promoting the understanding and research of this area,chatter suppression techniques are generally discussed within limited pages in the framework of comprehensive chatter-related problems.In recent years,the developments of smart materials,advanced sensing techniques,and more effective control strategies have led to some new progress in chatter suppression.Meanwhile,the widely used thin-walled parts present more and more severe machining challenges in their milling processes.Considering the above deficiencies,this paper summarizes the current state of the art in milling chatter suppression.New classifications of chatter suppression techniques are proposed according to the working principle and control target.Based on the new classified framework,the mechanism and comparisons of different chatter suppression strategies are reviewed.Besides,the current challenges and potential tendencies of milling chatter suppression techniques are highlighted.Intellectualization,integration,compactness,adaptability to workpiece geometry,and the collaboration of multiple control methods are predicted to be important trends in the future.
基金National Natural Science Foundation of China(No, 50575232).
文摘By turning a specifically designed conical part, complete process of metal cutting, in which the chatter occurs and expands, is recorded and analyzed. This process exposes that chatter vibration has two characters called continuity and break. The continuity character means that vibration extent enlarges continuously while chatter frequency is almost changeless as the cutting depth extends downwards continuously. The break one is that chatter frequency moves rapidly downwards to a lower level while chatter remains after the cutting depth reach another given value. It is confirmed through an exciting test that the two chatter frequencies obtained in chatter test belong to the natural frequencies of workpiece system and cutting tool system respectively. From the viewpoints of chatter energy supplying and chatter mass effect, the. chatter should occur on one of the two final executive components in its natural frequency. On this basis, a new chatter model with two chatter active bodies is proposed. This new model can better explain the above phenomenon, and adapt to chatter monitoring and improvement of component structure well.
