On-machine Measurement Of Valve Core Sphericity And Processing Analysis

With the development of society,spherical parts represented by valve cores have a wide range of applications in all walks of life.Ball valve is a typical valve with the advantages of simple structure and convenient use,and it is an important part of ball valve.The working environment of ball valve is often very harsh,so it has extremely high requirements on the surface quality and shape accuracy.Higher surface quality also brings difficulties to the milling process.Based on the se reasons,improving the core processing process and testing methods has become an urgent need for this industry.Therefore,this article starts from the basic principle of spherical grinding combined with mathematical tools such as coordinate transformation to study the on-machine measurement of sphericity and grinding proces sing parameters to provide references for actual processing.The main content of this article is shown as follow:(1)The mathematical model of sphericity evaluation on the machine which is used as the evaluation algorithm of sphericity measurement is established under the spherical coordinate system by using the least square method.Based on the precision machining center,the dial gauge and the latitude and longitude circle measurement method are combined to establish an on-machine measurement platform for sphericity.Three sets of experiments are designed for verification,and the resu lts of on-machine measurement and off-line measurement are compared.This result shows that two methods are basically the same.Finally,the error analysis of the measuremen t method is carried out.The error of online method mainly comes from the positioning erro r of the machine tool and the turntable,which can be ignored in the calculation.The main source of the offline measurement error is the direction of movement of the probe.If the probe moves in the normal direction of the contact point,The error can be reduced to 3.7% of the original.(2)Through robotics and related mathematical knowledge,the spherical grinding lines are simulated.Combining the principle of spherical grinding and coordinate transformation,the parameter equation of the grinding lines is calculated.Using MATLAB software to draw the simulation diagrams of the lines in the ideal state and the error state respectively.Then the basic characteristics of the lines and the influence of different errors on the characteristics of the lines are summarize.Finally,the influence of error on sphericity and surface roughness is analyzed,and the relationship between lines and processing quality is summarized.The denser the grinding lines,the lower the sphericity error and surface roughness.If there is an error that destroys the grinding lines,the quality of these processing will be reduced.(3)In view of the influence of grinding lines on the processing quality,the three parameters —— grinding speed ratio,number of grinding heads,and work piece radius are selected as representatives for research.First,the concept of line spacing is proposed to describe the density of lines.Subsequently,taking line spacing as the intermediate quantity,using the above-mentioned line characteristics and the relationship between the lines and the processing quality,the influence of the processing parameters on the processing quality is analyzed.Design experiments to verify the analysis results,and the experimental results are consistent with the theoretical analysis.Finally,based on the results obtained from the verification,guiding suggestions for actual processing are put forward in terms of improving processing quality and saving processing time.