Research On Error Compensation Of CNC Machine Tool And The Influence Of Uniaxial Force On Geometric Error

CNC machine tool is the foundation of the manufacturing industry.Improving the machining accuracy of the workpiece is the unremitting pursuit of manufacturing industry,and high-precision machine tool is the only way to achieve this goal.The geometric error of a machine tool is an important factor that affects the machining accuracy of the workpiece.Especially for high and precision machining,the processing quality of the workpiece is seriously affected by the geometric error of CNC machine tool.Therefore,understanding the characteristics of machine tool geometric errors can not only provide directions for preventing and reducing geometric errors of machine tools,but also provide basic parameters for software error compensation of CNC machine tool to ensure the overall machining accuracy of machine tool.This paper mainly studies the influence of position error compensation technology on the geometric error of the machine tool,and summarizes the variation law of the geometric error of the machine tool under the condition of uniaxial force.The main contents are as follows:(1)The geometric error model of three-axis CNC machine tool is established.Using the kinematics theory of multi-body system,the structure of machine tool is described in detail and its corresponding multi-body system topology is analyzed,and the corresponding low-order body array is calculated.Using the homogeneous coordinate transformation and the motion relationship between each body to derive the corresponding feature matrix,through the coordinate conversion of the machine tool tip point to the workpiece processing point,the geometric error model of the three-axis CNC machine tool is constructed.(2)The influence of position error compensation on the geometric error of CNC machine tool is studied and found.Choose a convenient and time-saving geometric error measurement method,use precision laser interferometer and ball bar to measure the eighteen geometric errors of the machine tool,and complete the geometric error measurement after the compensation of the position error of the CNC machine tool.Through the analysis,the influence law of the compensation of the position error on the machine tool geometric error is found,and it is concluded that the position error compensation can not only improve the positioning accuracy,backlash and repeated positioning accuracy of the CNC machine tool,but also effectively improve the angular and straightness error of the machine tool.But it has little effects on the squareness error.(3)A measuring system of geometric error of uniaxial force is proposed,and the influence of uniaxial force on geometric error of CNC machine tool is analyzed and summarized.Aiming at the problem of cutting force produced during the actual machining of CNC machine tool,a uniaxial force geometric error measurement system is proposed,which simulates the cutting force produced by the actual cutting process of the machine tool by loading constant loads of different weight.Under the action of a constant load,laser interferometer and ball bar are used to measure the geometric error of the machine tool,and the geometric error after the position error compensation is measured.It is found that with the increase of the loading weight of the machine tool table,the positioning error of the CNC machine tool is increasing,but the angular error and straightness error are decreasing.After the position error compensation,the positioning error of the CNC machine tool is decreasing,the angular error is increasing and the straightness error is decreasing with the increase of the loading weight of the machine tool.