Study On Some Key Techniques For Industrialization Of Traveling Wave Type Rotary Ultrasonic Motors

This dissertation is a part of NSFC-Guangdong Natural Science Foundation(No.U0934004), the task is to study some key techniques for industrialization of traveling wave type rotary ultrasonic motors(TRUM).A traveling wave type rotary ultrasonic motor is the most typical ultrasonic motor. This motor is close to the traditional electromagnetic motor in the external shape and the output mode. Its operating mechanism of direct drive creates many excellent features. It is one of the most widely using ultrasonic motors and therefore becomes a class of products with the best industrialization prospect. As high-tech products of interdisciplinary integration, ultrasonic motors have a relatively short history. Thus there are many problems in the process of industrialization. In order to develop ultrasonic motors with low manufacturing costs and high output performance, this paper researches some key techniques for industrialization of TRUM. Main contents and the results are summarized as follows:(1) The operation mechanism of TRUM is analyzed. The problems on stator, drive interface and increasing output torque of the products are pointed out.(2) For the electromechanical coupling relationship of the stator, the finite element method is applied and the excitation effects of the stator vibration modes are analyzed. Two typical stators of TRUM are compared, and the effect of tooth bevel on the stator vibration characteristic is summarized. To deal with the consistency of two-phase operating frequencies of the stator in the volume manufacturing, the dynamic parameters on the stator operating frequency are analyzed, and a radial tooth chamfer approach to adjust two-phase frequencies is proposed.(3) To achieve mass production of the ultrasonic motors, the idea that the method of reflow soldering in advanced electronics manufacturing field substitutes the traditional adhesive method is proposed. According to actual requirements on stator integration, the test system of reflow soldering is designed and constructed. The quick connection of the stator elastomer and piezoelectric ceramic element is implemented. Effect factors of reflow soldering on the stator performance are experimentally studied. Connection layer parameters directly related to the stator vibration characteristics are analyzed. When six kinds of solder are selected, the mechanical properties of the weld interface and vibration characteristics of soldering stator are further researched. It is pointed out that the solder material is one of the main factors affecting the welding stator performance.(4) According to the stator vibration characteristics with high frequency and slight amplitude during the TRUM operation, the effect factors on output performance of TRUM drive interface are are analyzed. The equivalent stiffness model based on surface morphology is established, the effect of surface morphology parameters to TRUM output performance is summarized. Main ways to reduce adhesion area of the drive interface of the stator/rotor to increase output performance are induced, and the impact of the rotor stiffness coefficient to the drive interface pressure is first found. The impact of modified preparation to mechanical parameters of crosslinked UHMW-PE composites is experimentally studied. The analyses are implemented from the theoretical aspects of equivalent stiffness model, the friction material shear deformation and the rotor stiffness matching. The reason why the drive interface uses this new friction material to enhance TRUM output performance is discussed.(5) For a series of questions in TRUM with combined structure, the axial vibration model of TRUM with dual stator/rotor is established. The possibility is proved that axial vibration coupling and vibrational energy transfer occur between two groups of stator/rotor. A TRUM with single ladder shaft and dual stator/rotor is proposed in accordance with the theory of vibration isolation. Comparative experiment proved that this novel TRUM has obvious advantages to the traditional one: when the motor’s output speed and transient characteristics remain unchanged, output torque is increased by 80% and power density is increased by 43.1%. Based on the stable operation of this novel TRUM, the operation mechanism is studied. The circumferential output model based on dual traveling wave is established. The results show that this novel TRUM has good tolerances to the dual traveling wave’s amplitudes, frequencies and phases. The torque synthesis efficiency based on dual traveling wave is up to 90%. Two environmental experiments for this novel TRUM are carried out. One is under environment of vacuum and high/low temperature, the other is under vibration environment. Experimental results show that this novel TRUM can adapt to extreme environment or vibration environment, thus the novel motor has high values in use and industrialization.