Theory Analysis And Implementation For Improving Turning Precision Of Revolutional Component With Three Degrees Of Freedom

The turning process is an important part of machining process. Compared with ordinarycylindrical turning, complex surface of revolution components maintains specific processcharacteristics, mainly because the projection of the outer contour is non-circular curve.Ordinary CNC system can only deal with simple lines and arcs, so it is limited greatly onaccuracy and efficiency.Based on the residual surface layer and its related factors, mathematical models wereformulated according to tool movement in the complex surface of revolution components duringturning process, which introduced inclination angle as a new variable，and in return，achievedprecise control of tool rotation angle. The influence of the quality by ordinary turning, resultedfrom tool cutting edge angle and tool minor cutting edge, were explored through experimentalanalysis, and then the trends and practical significance of the curve in the cutting process wereanalyzed.A cutting method with3degrees of freedom (3DOF) for complex surface of revolutioncomponent based on ordinary two degrees of freedom process was proposed. Three variableswere integrated to achieve the interpolation of complex curve，and adjustment of tool posturewas accomplished. Note that, the adjusted posture ensures the tool be perpendicular to thetangent line of the busbar, keeps the cutting edge and minor cutting edge angle be constant，andguarantees the contact between the tool and the work-piece stable. Thereby, the turning accuracy,surface quality and processing efficiency were improved. This novel idea was generalized byCNC theoretical description，and mechanism about how the proposed variables control strategyselection process was pointed out.The proposed3DOF numerical control cutting principle and control theory was tested bycorresponding modeling and simulation with software Simulink. Furthermore, a rotary toolholder was designed for driving tools in precision, the input parameters and feedback controlprocesses was declared, and the soft and hardware platform of the3DOF lathe was predefined.Compared with the traditional two DOF turning machining, the experimental results haveindicated that the proposed approach can achieve higher precision，better stability as well asgreater self-adaptability, and it can reduce the machining error of complex surface of revolutionparts to42.9%. Thus, the machining accuracy of the traditional CNC lathes can be improvedsignificantly only with the3DOF approach.