内圆磨床毕业设计翻译原文.doc

Investigation on critical speed and vibration mode of high speed grinder Abstract The influences of the grinder spindle’s major structural parameters on its vibration mode were investigated. Based on the transfer-matrix method and taking into consideration the gyroscopic couple, the shear, the variable cross-section and other influential factors, a dynamic model was established for the multi-disk rotor of the rotor-bearing system of the grinder spindle. The critical speeds of first three orders, the modes of variation and other dynamic characteristic parameters of the grinder spindle were programmed and calculated. The influences of the axial pre-tightening force of the bearing, the span of the fulcrum bearing as well as the changes in the front and rear overhangs on the critical speed of the rotor-bearing system on the grinder spindle and their pattern of changes were analyzed. The results showed that the working speed of the spindle system is much lower than the primary critical speed and can therefore stay away the resonance range effectively. 1. Introduction The spindle of high speed grinding machine tool is a typical high speed bearings-rotor dynamics system, and its rotating speed far surpasses the critical speed of the low order system. The realization of dynamic balance is associated with the performance and stability of the whole equipment. The research of rotor dynamic balance mainly involved the rigid rotor before the 1950s [1-4]. With the increase of the rotating speed and the flexibility of, the research on the method of flexible rotor’s dynamic balance appeared. The early stage method of flexible rotor’s dynamic balance was put forward by Feder, which was later called vibration balance method or modal balance method. The number of times of start-up of high-speed balance was relatively less, and is of high sensitivity. The low order mode would not be affected when the balancing of high order mode was conducted, but identification was not balanced[5-7].