Research On The Chatter Stability In Turning Of Weak-rigidity Pure Iron

Pure iron material has excellent performance on electromagnetic,hence it is widely utilized to machine key components in electronic industries,national defense industries,aerospace industries and so on.CNC turning is generally used to machine rotary-type components made of pure iron.However,the chatter tends to happen in CNC turning machining of weak-rigidity components made of pure iron if the unreasonable processing parameters are selected,and the chatter can limit the improvement of machining quality and producing efficiency.Therefore the accurate prediction of chatter stability in CNC turning machining of weak-rigidity components made of pure iron is of great significant to the optimization of processing parameters and the improvement of machining capacity.Aiming at the CNC turning machining of weak-rigidity components made of pure iron,the research on the chatter stability prediction in turning machining based on the regenerative effect is carried out in this paper,and the main research contents are as follows:(1)Basing on the macro-mechanics of metal cutting,a modeling of turning forces,which takes the shearing effect and the rubbing effect into account simultaneously,is proposed in this paper,and the effect of the tool nose radius is considered in modeling by discretizing the uncut chip area.Aiming at nine turning force coefficients in proposed modeling,a novel identification method based on the Powell’s optimization method is presented.In addition,numerous actual turning machining tests are conducted on the components made of pure iron to verify the accuracy of the modeling.(2)According to the actual situation of turning machining,a turning machining dynamic model considering the dynamic characteristics of tool and workpiece is built in this paper.Meanwhile second-order differential equations with delays are constructed based on the regenerative effect to represent proposed dynamic model.Besides,the modal parameters of tool and workpiece are identified through the experimental modal analysis.(3)By means of transformation,the state-space representation of proposed turning machining dynamic model is constructed in this paper.In addition,the latest second-order semi-discretization method is extended,and the transition matrix of system in single period is obtained.The chatter stability in turning machining is predicted according to the Floquet theory.Furthermore,the effects of the modal parameters of processing system on the chatter stability are explored through the numerical simulation.(4)According to the stability lobe diagram obtained by the numerical simulation,the verification tests under different processing parameters are conducted.And overall,the test results indicate that the stabilities predicted by stability lobe diagram agree well with the stabilities of actual turning machining tests,and the methods proposed in this paper can achieve the accurate prediction of chatter stability in CNC turning machining of weak-rigidity components made of pure iron.