Study On The Form Accuracy In-situ Measurement And Compensation Technique Of Roller Mold

Surface form accuracy is one of the most important index for evaluating the qualification of roller mold.There is a certain deviation between the actual surface profile and the ideal profile of processed mold due to external and internal factors,which is reflected on the workpiece in the form of surface error.With processing requirements are becoming higher and higher,it is more and more difficult to ensure the surface form accuracy of roller mold only relying on the machining accuracy of the machine tool itself.The common method to improve machining accuracy is to establish and analyze various error models during the machining process so as to compensate them separately.Machining accuracy of the machine tool are affected by many factors such as geometric error,thermal error,tool wear and random errors.It is relatively precise to measure and calculate the single error's influence on the machining accuracy of the machining tool,but time-consuming,inefficient and costly.Therefore,improving the surface form accuracy of roller mold through high-efficiency and low-cost processing methods is an important task.It has been found that the comprehensive error of various errors will be directly reflected on the surface of the processed workpiece under the specific process conditions,thus forming the machining error.This paper analyzes the surface form error and generates the compensation data by in-situ measurement of the precisionmachined roller mold,then compensates and reduce the surface form error of roller mold so as to meet the requirement through slow tool servo diamond turning technology,without increasing the machining accuracy of the machine tool itself or the establishing the error model.Therefore,this paper mainly studies the following sections:Firstly,it is necessary to analyze the factors that influence the surface form error of roller mold.Through the spatial motion analysis of the precision-machined roller mold,an absolute coordinate system with the axis average line as the coordinate axis is established,and the three-point error separation method is used to separate the rotation error and roundness error of the measured section.The roller mold is divided into two types,three-point method and two-point method are used to separate the motion error component of the carriage slide along the axial direction of the roller mold,and the surface form of the roller mold is reconstructed in the absolute coordinate system.Secondly,according to the surface form error evaluation criteria stipulated by the national standard,the surface form error of the precision-machined roller mold is studied by the least square method and the minimum zone method error evaluation algorithm to determine whether it meets the processing requirement.The principle of error compensation and slow tool servo diamond turning technology is studied,thus according to the reconstructed form features of roller mold,the compensation data of roller mold and the tool path for slow tool servo diamond turning is generated through data processing method.Finally,according to the in-situ error measurement and compensation method mentioned,a data processing system is designed to achieve measurement signal acquisition,calculation of surface form error and generation of error compensation data.In order to explain the feasibility of in-situ surface form error measurement and error compensation method,surface form error measurement and compensation processing are performed on the precision-machined roller mold,and the machining results before and after compensation are compared.It can be seen that the error compensation method proposed in this paper can significantly reduce the processing error of the roller mold,and the surface form accuracy of the roller mold is significantly improved.