Geometric Error Identification Of Gear Measuring Center Based On Ballbar

With the improvement of gear manufacturing accuracy,there are higher requirements for the measurement accuracy of the gear measurement center of its main measuring instrument.Geometric error is the main source of error that affects the measurement accuracy of the gear measurement center,and its rapid detection and accurate identification are the basic guarantee for improving the measurement accuracy of the gear measurement center.Ball-bar is a high-precision error detection tool that is easy to use and fast in measurement.It has become the mainstream tool for error detection in the machine tool field.However,the error detected by the ball-bar not only includes geometric errors,but also coupled with motion errors.The main purpose of this paper is to use the measurement data of the ball-bar to eliminate the motion errors of the gear measurement center and identify the geometric errors.This article mainly completed the following work:1.Analyzed the error items of the gear measurement center contained in the collected data of the bar instrument and the grating ruler,and proposed the principle of geometric error identification of the gear measurement center based on the ball bar.According to the topological structure of the gear measuring center and the installation position of the ball-bar,the geometric error identification measurement coordinate system of the gear measuring center based on the ball-bar is established,and the geometric error identification model is established based on the multi-body theory and the principle of error identification.According to the geometric error model,the geometric error on the circular trajectory of the gear measurement center is estimated,and the estimated value of the comprehensive result of the geometric error is obtained,which provides a theoretical prerequisite for detecting the error of the gear measurement center using a ball-bar and identifying the geometric error.2.Aiming at the CNC gear measuring center without circular interpolation function,with the idea of "short straight line instead of circular arc" a "circular motion" program based on C language is designed.Two kinds of ball-bar running trajectories were planned and designed.Taking the circular trajectory movement of R-T surface as an example,geometric error detection experiments were carried out,and the gear measurement center error data including motion error and geometric error were obtained.By collecting the real-time value of the grating during the movement,the coordinate points on the circular trajectory containing only the movement error are obtained.Laid a foundation for the subsequent identification of geometric errors.3.By analyzing the coordinate representation,sampling distribution and sampling density of the data collected by the grating ruler and ball-bar,an iterative registration algorithm for measuring point data with different benchmarks is proposed.Based on the measurement data of the grating ruler,select the initial registration point,registration neighborhood,and iterative search step length of the ball-bar,determine the iteration termination condition according to the geometric error identification model and the detection value of the single geometric error item,and perform the initial point registration.And calculate the error of the ball-bar data and the grating ruler data registration one by one,using MATLAB as a tool,develop a registration algorithm program,from the error detection data of the ball-bar,identify the measurement data that only contains geometric errors.The result accords with the expected theoretical value.In this paper,the geometric error of the gear measuring center is identified from the error data obtained by the ball-bar and grating detection.It proves that the ball-bar is also suitable for measuring machines without arc interpolation,and provides a measure of the geometric error of the gear measuring center.The new method has further expanded the scope of application of the ball-bar.