Structural Design And Study On The Preformance Of The High-speed Ceramic Motorized Spindle

Motorized spindle unit not only simplifies the spindle structure, improves the speed,but also greatly improves the accuracy and efficiency of the high speed machining. Withthe development of high-speed machining technology, the requirement to the static anddynamic performance of motorized spindle is increasingly high. Against the generalproblems of lower speed, poorer dynamic and static characteristics, and lower accuracystable to the domestic motorized spindle, silicon nitride(Si3N4) ceramic high-speedmotorized spindle is designed by using the excellent performance of smaller density, largeelastic modulus, higher hardness and lower thermal expansion coefficient to engineeringceramic. Then its dynamic and static characteristics is analyzed. Specific researches are asfollows:(1)The structural design of the ceramic motorized spindle is designed. First, thesilicon nitride ceramic is chosen as the material of the shaft, the configuration of bearing isdetermined, the interference coupling device between shaft and rotor was desinged and theinterference is confirmed. Next, the overhang and span of the spindle is desinged andcalculated. Then the optimal span is confirmed. Finally, the type and pattern of motor ofthe spindle is chosen, the hybrid ceramic angular contact ball bearing is determined, thelubrication and cooling device is confirmed.(2)The static characteristics of the ceramic motorized spindle are analyzed. The solidmodel of the spindle components is built and its stress, displacement and strain areanalyzed by using the three-dimensional software SolidWorks. Then the static stiffness isobtained and compared with the result of steel spindle with the same size. This papercalculates the static stiffness using theoretical method and makes a comparison with therusult by using finite element method. The two results are verified with each other.(3) The dynamic characteristics of the ceramic motorized spindle are analyzed.Importing the model from SolidWorks into Workbench and making a modal analysis, thefront six natural frequencies and mode shapes of the ceramic motorized spindle areobtained and compared with the results of steel spindle. After calculating the centrifugal force, the harmonic response analysis of the model is carried out, the variation of spindledeformation along with frequency is obtained. The first natural frequence is calculatedwith transmission matrix method. At last, this paper makes a comparison with the resultsof the finite element method.According to the research, the new ceramic spindle owns favorable static anddynamic performance. That the speed of motorized spindle is further improved is moresuitable for high-speed machining.