Research On The Key Technology And Equipment Development Of Internal Diameter Measurement Of Cylinder Liner In Internal Combustion Engine

Internal-combustion engine liner is one of the indispensable components of engine piston assembly.Its production process has been automated,but its process quality control is still in the state of offline sampling inspection.With the implementation of the production line intelligent transformation project,online full inspection technology has become a key bottleneck.Therefore,this paper will carry out research on the key technology of online diameter measurement of cast iron cylinder liner,and develop and design an inner diameter automatic measuring machine on this basis.Specific research contents are as follows:(1)According to the production cycle requirements of the production line,the process medium,the production environment and the surface roughness index of the cast iron cylinder liner,the contact-type automatic measurement technology,including linear displacement sensing and inductive displacement sensing,and aerodynamic measurement technology such as buoy type and water column type,as well as non-contact automatic measurement technology such as photoelectric type,are compared and analyzed.The eddy current sensor is selected as the inner diameter measuring probe of the cylinder liner.The mathematical model of inner diameter measurement is established,and the theory and method of multi-dimension calibration based on calibration ring gauge are put forward.It is shown by bench test:The test result is highly consistent with the test result of the calibration tool,and the measuring accuracy is less than 1/5 of the cylinder liner tolerance,which fully meets the operating requirements.(2)A gantry type eddy current cylinder liner inner diameter automatic measuring machine is designed,including cylinder liner tooling assembly,sensor trim assembly,ball screw,air float damping,marble platform,photoelectric sensing and control system.The influence law of the mechanical system errors such as vertical guide rail installation tilt,the non-coaxiality between the hollow rotating platform and the pneumatic chuck on the measurement results of the inner diameter of the cylinder liner are analyzed.The value range of each variable when the error of mechanical system is no more than 0.01mm is determined by the error distribution map.A method of system error control and compensation for inner diameter automatic measuring machine is presented,the error of mechanical system can be less than-~-mm.(3)Using random sampling,10 cylinders are taken from a batch of liners.Repeatability of 10 cylinder liners were measured by automatic measuring machine,the maximum error is 5.16%,which is much higher than the acceptance criterion of no more than 10%;Similarly,10 cylinder liners were measured with the developed automatic measuring machine prototype and CMM respectively,and the comparison of measurement results shows that:The measuring results of the two methods have a good consistency,the maximum measuring error is 0.0132mm,less than 1/5 of the cylinder liner tolerance,so the developed automatic measuring machine meets the design requirements.(4)The prototype of the developed inner diameter automatic measuring machine is connected to the existing automatic cylinder liner production line for trial production verification.From October 2019 to now,it has been running normally on the production line of a company and fully meets the online measurement requirements of the production line,which has obvious application and promotion value.