Analysis Of The Static And Dynamic Characteristics Of Hige-speed Spindle Considering Grind-matching Clearance

With the rapid development of high-speed machining technology and thesuccessful application, there is a growing emphasis on the study of high-speed spindlesystem. Spindle unit combines spindle with frequency motor, out of the traditional beltor gear drive to achieve a spindle system’s "zero transmission". Spindle unit is a corefeature of CNC machine tools, its static and dynamic performance directly determinesthe processing performance and reliability of the machine. The grind-matchingclearance between the bearings`inner rings or outer ones of the high-speed spindle mayhave some impact on its working characteristics. Therefore, the study of the staticcharacteristics of the spindle unit motion is significant.The simulated-dynamics characteristics under different working conditions wasperformed by an analysis software predicting high-speed rolling bearing performancedeveloped HIT. The static and dynamic stiffness of the angular contact ball bearing isabtained.The effect of bearing stiffness on the static and dynamic characteristics of theGDZ-60`s spindle system was analyzed under the condition of normal grinding-in andabnormal grinding-in of the bearing in the front of spindle by ANSYS. The statics studyrevealed that the spindle static stiffness incresses with the incress of the bearings`preload when the bearings normally working. The natural frequencies and main modeswere abtained by spindle modal analysis. The spindle harmonic analysis displayed therelationship between the radial runout of the spindle front end and grind-matchingclearance, thus acquiring the spindle dynamic stiffness. Taking the spindle stiffness asobjective function the structural optimization design was performed and consequentlythe dynamic stiffness incressed30per cent.The spindle static and dynamic stiffness were respectively abtained by statics anddynamics analysis under the condition of grind-matching clearance of the front endbearings. Compared with the state of normal grinding-in, the bearings outergrind-matching clearance significantly impacts the spindle static characteristics. Theresearch of the cage sliding ratio and the bearing life under the biggest grind-matchingclearance exhibited that the appearance of grind-matching clearance does not cause thecage to slide and has impact on the bearing life to some extent. The study of the spindlestatic and dynamic characteristics when the front end bearings is in the state of switchfrom one to double showed that the bearings ourter grind-matching clearance canconsiderably affect the spindle dynamic stiffness.