Research On The Key Technology Of Automatic Integrated Measurement For Asymmetric Shafts

The asymmetric shafts represented by eccentric shaft,crankshaft and camshaft are the key parts of the mechanical power equipment.The manufacturing quality of the shafts affects the performance and synergy of each power unit.Roundness measuring instrument,coordinate measuring machine and other traditional precision measuring instrument cannot meet the testing requirements of the various form and position error.It plays a great significance to research the high efficiency and high precision integrated detection technology according to the characteristic of asymmetric shafts.The paper takes asymmetric shafts tracing measuring instrument as research platform which is developed with the enterprise together.In order to complete high precision automatic integrated detection of asymmetric shafts form and position errors,key technology research such as automatic measurement method of asymmetric shafts and development of integrated measurement software for shafts,measurement data preprocessing and form and position error evaluation methods,simulation analysis of workpiece surface contour surface measurement,workpiece contour surface measurement test are conducted.The specific research as follows:Measurement requirements are analyzed according to the main feature of the asymmetric shafts.Tracing measurement method for asymmetric shafts is designed according to the asymmetric structure,the multi journal and the high phase accuracy.After analysing hardware and system structure of the measuring instrument,the system error caused by the parallelism between the air guide and the rotary axis of the measuring instrument are found.Relative position calibration model between workpiece coordinate system and measuring coordinate system based on ring gauge is established for eliminating the system error.After designing the function and architecture,the integrated measurement software for shafts is developed which takes the measurement data processing and the form and position error evaluation algorithm as the core.The main signal composition of the original measurement data for the workpiece contour surface is analyzed,the relationship between the cutoff wave and the cutoff frequency is clarified.The zero phase shift characteristic of gaussian filter is preferred after comparing the application of the cutoff wave and the cutoff frequency in different filtering methods.The nonlinear objective function optimization model is constructed to compensate the limitation that the least square circle method cannot realize the roundness error evaluation of non-circular circle.To improve the cam lift error assessment accuracy and efficiency,cam eccentricity correction and lift error evaluation model are established.The model takes the center of the cam as the design datum and combines the sensitive point method and the least-square method.The main parts installation error of the measuring instrument and spindle rotation error are researched.Simulation analysis of the tracing measurement device installation error,top geometric center calibration error and head and tail top coaxial degree for workpiece form and position error evaluation are analyzed.The main reasons for the spindle rotation error of the whole machine system are studied.The method of spindle rotation error separation based on multistep method is proposed.The simulation results show that the method can effectively realize the spindle rotation error separation during the measurement process.Based on the asymmetric shafts tracing measurement method and the integrated measurement software which takes the measurement data processing and the form and position error evaluation algorithm as the core,the multi-step method of the spindle rotation error separation tests are completed on the SE13-J10 measuring instrument platform.And the validity of the spindle rotation error separation is verified.Workpiece form and position error evaluation tests are researched between the measuring instrument and the ADCOLE 1200 SH crankshaft and camshaft.The results show that the measurement accuracy and repeatability of the measuring instrument can meet the measurement standard of the special measuring instrument.