Modal And Loading Experimental Study On High Speed Motorized Spindle

High speed machining (HSM) has become the mainstream of manufacturing for drastically increasing productivity, reducing production costs and improving the product quality. HSM is also a promising advanced manufacturing technology. In the realization of HSM, machine tool generally plays an all-important role and high speed motorized spindle is the key technology for a machine tool. The machine tool equipped with high speed motorized spindle has characteristic of the zero-transmission and simplified of the machine structure. With use of new mechanical structure, the high speed motorized spindle has much better dynamic performance in response to the high demands in this machine. In general, overall performance of high speed machine in terms of the machining precision and productivity is largely dependent upon the performance of the equipped high speed motorized spindle.This thesis is funded by the National Natural Science Foundation, China (No.50675233), Chongqing Municipal Important Science and Technology Key Project, China (CSTC, No. 2006AA3010) and Chongqing Municipal Important Science and Technology Key Project, China (CSTC, No. 2005AC3029). The experiment of modal,vibration and dynamic loading on high speed motorized spindle are researched. The major contribution of the work is summarized as followings.Based on the theory of mode analysis, the mode experiment is carried out under the 60 000 rpm high speed motorized spindle in order to acquire the modal parameters, such as natural frequency, damp and mode shape. The experimental results exhibited that modal parameters from the test are suited the requirements of high-speed and high-precision manufacture. The overall experimental method and procedure are also introduced.Due to the vibration of the high speed motorized spindle working in state affecting the high-precision manufacture terribly. The maximum speed of 60 000 r/min motorized spindle's vibration measurement test and modal parameter identification under the different speed is carried out. The time-domain signal and frequency-domain signal of its key positions are obtained. Several measure points'acceleration and speed are analyzed and compared with the theory value, certificated them if suit the requirements of high-precision manufacture and the accuracy of test methods. The primary reasons of vibration of the motorized spindle are put forward。The SSI is used to identify the modal parameters ,and the possibility of it working in the resonance area is excluded.Loading and measuring the load applied on a high speed motorized spindle in the non-machining state is an important issue in performance evaluation of high speed motorized spindle. A new method is developed through modifying a dynamometer to make the loading possible in the experiment. According to the different rotating speed, two types of dynamic loading test ways which are the inter-drag method and the non-contact method are proposed. The structure and principle of the inter-drag loading method are described in detail. The system can not only load to the high speed motorized spindle, but also measure basic parameters of the high speed motorized spindle and present the corresponding curves which make it visible for states of the high speed motorized spindle at different working points. The inter-drag loading system is applied in experiment on the high speed motorized spindle in which the highest rotating speed is 15 000 rpm. The characteristic curve of this high speed motorized spindle is depicted. Analyzing and dealing with the test data, the inherent characteristic and existent problem of the motorized spindle are gained. Proposed method makes it possible to accurately loading on a high speed motorized spindle.