Research On Measuring Methods Of The Geometric Errors For Guideway Installation Surfaces Of CNC Machine Tools

The performance of feed system from cnc machine tool depends not only on parts but also on the assembly accuracy of guide rails.As a benchmark of feed system the assembly precision of guideway plays a key role in machine tools to the performance and is the basic standards of positions and movings for main parts.Therefore it is the main reason of error of shape and position.Usually micrometer and surface scraping can ensure assembly accuracy of guidway in engineering practice.However the measuring accuracy has a large randomness.The operator's proficiency and experience have a great influence on it and lower efficiency.So it is impossible to realize digital assembly process by that ways.Therefore,researching a digital measuring method and developing a corresponding device have important theoretical meaning and engineering applying value for improving assembly accuracy and measuring efficiency of guideway and realizing digital assembly process in the process of assembling of guide rails.Using the high precision laser,this paper designed a digital testing instrument of straightness and flatness for the assembly benchmark of guide rails,put forward the corresponding measuring principle,deduced an evaluating algorithm of straightness and flatness,developed the corresponding software.The main content of this dissertation are as follows:(1)Based on the traditional contacting testing method,a new three liner contacting instrument of flatness was developed using the variable scale measurement principle.And the measuring software was also developed.The measurment scheme of flatness and straightness for the installation datum plane of guideways was propposed.(2)According to the geometrical relationship of the instrument,the detecting algorithm and the reconstructing algorithm of the corrugated line of normal plate projection(CLONPP)for an asperity plane.Using the fractal function of Majumdar-Bhushan,a surface morphology of the corrugated line was constructed to simulate the projection of a plane on its nornal plane.By the computer simulations,the above corrugated line was detected using the detecting algorithm to evaluate the straightness and flatness.Futhermore,a corrugated line was reconstructed with the detected data of simulation.The simulation results verified the effectiveness of the proposed scheme.(3)This paper proposed a measuring method of the CLONPP of guideway installation surfaces for CNC machine tools.The detecting experiments of asperity surfaces were conducted to evaluate their straightness and flatness using the detecting device and the measuring method.Finally,the CLONPPs of the asperity surfaces were reconstructed,respectively.(4)Taking the detection of three dimensional rough planes as examples,the effects of asperity surface contact and the device form error on the detecting error were analyzed using an ideal plane contacting with an asperity surface,an asperity line contacting with an asperity surface,an asperity surface contacting with an asperity surface.Based on the above analysis results,the indeces of the device system errors proposed to ensure the detecting accuracy.