Research On The Identification Method Of Geometric Error Of Cradle Five Axis NC Machine Tool

As the basic unit to realize precision and ultra precision machining,five axis CNC machine tool can complete the cutting of complex thin-walled parts with multi attitude and multi angle.Because of the existence of rotating axis,five axis CNC machine tool introduces more geometric error factors.At present,the geometric error detection method of translational axis lacks consideration of actual machining error and spindle deformation.The detection instruments related to the position of rotating axis and unrelated geometric errors have high installation and adjustment accuracy and low detection effi ciency.In view of the shortcomings of current research,two methods are proposed to detect the geometric error of translational axis and rotary axis respectively,and the error of five axis machine tool is developed Field prediction system.This paper takes Tuopu VMC-C50 five axis CNC machine tool as the research object.Firstly,the geometric error sources of five axis machine tool’s translational axis guide,swing basket,turntable and other machine tool’s motion units are analyzed.Based on the theory of multi-body system,the error transfer chain is established,and the geometric error term of translational axis and 12 position error elements of two rotating axes are defined.At last,the model of tool space position and attitude in ideal and real state is established by using the second coordinate transformation.A new method of indirectly identifying the geometrical error of the translation axis by detecting the features of the processed feature samples is proposed.A "three line" identification model is used to solve the geometric error term of the X and Y translation axis.The influence of the deformation deflection of the joint surface of the spindle is considered in the identification of the geometrical error of the Z axis,which can reflect the geometric error in the actual operation of the five axis machine tool.The detection method of feature sample has low cost.Ordinary machine tool users can fully grasp the detection steps.It is easy to operate and suitable for small and medium-sized machine tools with compact structure.A new method to detect the geometrical error of the rotating axis of five axis machine tool is proposed.Firstly,based on the identification model of the position error of the rotating axis measured on the machine,a multi d egree of freedom spherical contact scheme is proposed.The contact trigger probe installed on the spindle is used to detect the contact of the precision ball installed on the turntable,and a series of spherical detection data are obtained The solution mod el of spherical center is established.Analyze the position error of the rotary axis obtained by the calibration,get the rule of the position error of the turntable changing with the angle of the swing basket,analyze the change of the space error field of different machine tools under the combined motion attitude of the two rotary axes,make the change rule of the space error field visible,and provide accurate and intuitive data for the space error compensation.The experimental results show that the ide ntification method is accurate and reliable,and the detection device is simple and efficient.