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1、外文资料与中文翻译Micro-feed Mechanism with High-Resolution and Large-StrokeBased on Friction DriveHaitao Liu, Zesheng LuSchool of Mechantronics Engineering, Harbin Institute of TechnologyABSTRACTBased on friction driving principle, design a long stroke length and high resolution walking micro-feeding device
2、 driven by piezoelectric ceramic elements and combined with the screw shaft and aerostatic guide way. The design was made to the adjustable preload device by flexible four-bar linkage. The static properties of flexible linkage device are analyzed with FEM. The transmission characteristics of micro-f
3、eeding device are exhaustively analyzed.Keywords: Friction drive, Piezoelectric actuator, Flexure hinge,Finite element1. INTRODUCTIONAspheric optics has been widely used in industries such as aviation, aerospace, national defense and so on. However, the manufacture of large aspheric optics faces man
4、y problems such as great difficulty, low efficiency, high cost, increased requirement on process equipment etc 1, 2 . In order to arrive at high precision, the micro displacement resolution of ultra-precision machine must be further advanced, so as to compensating the processing error online. Theref
5、ore, the design of micro-feed mechanism has become one of the key technologies 3-7 . PZT is the new micro-feed mechanism developed in recent years. It has the advantages such as small volume, large power, high resolution, and high frequency response and so on and phenomena such as no heating, no bac
6、klash and mucosity, so its widely used micro controller in micro-feed mechanism. Nowadays, friction gearing mechanism is gradually been acquired and used 8, 9.2. STRUCTURE AND OPERATING PRINCIPLE OF MICRO-FEED MECHANISMThe micro-feed mechanism is made up of three parts: friction gearing, ball screw
7、and static-pressure air-bearing guide way. Micro-feed mechanism uses the piezoelectricity ceramic friction gearing block, which twist up the sleeve and drive the ball screw, so as to bring along the air-bearing guide way to realize the micro-feed movement. The structure is shown as Figure 1.1-Bearin
8、g bracket 2-Friction gearing block 3 Friction gearing sleeve 4-Static-pressure air-bearingguide way 5- Ball screw 6- Piezoelectricity ceramic base 7-Piezoelectricity ceramic used for feeding Figure 1: (a) Structure of the feed mechanismAs shown in Figure 2, the operating principle of the feed mechan
9、ism is that, friction gearing sleeve connects with ball screw, four friction gearing blocks are placed symmetrically at both sides of the sleeve. Each block is droved by the corresponding piezoelectricity ceramic used for feeding and is gripped by the corresponding gripping mechanism, which is drove
10、d by the piezoelectricity ceramic used for gripping to produce clamp force. When feeding mechanism works, the piezoelectricity ceramic used for gripping on the same side drive both the friction gearing blocks to work in certain orderliness, so as that the friction gearing sleeve turn continuously.Fi
11、gure 1: (b) Picture of the feed mechanismFigure 2: Operating principle of the feeding mechanism3. DESIGN OF THE ADJUSTABLE PRETIGHTENING MECHANISMAn adjustable retightening mechanism is required in the friction gearing mechanism, which must has enough pretightening force. The typical pretightening m
12、ethods are plate spring pretightening mechanism, helical pretightening mechanism, and air pressure pretightening mechanism and so on. The retightening mechanism designed in this paper is flexible parallel four bars mechanism. Its droved by piezoelectricity ceramic to supply pretightening force. The
13、pretightening force can be changed by controlling the input voltage of piezoelectricity ceramic.As shown in Figure 3, use the finite element software to analysis the static characteristic. When the drive force of piezoelectricity ceramic is 500N in maximum, the rigidity of flexible four bars mechani
14、sm, analyzed by finite element software, is K=24. 1 5N/m, and the maximum stress of flexible hinges is =32.7Mpa. If there is no distortion in flexible four bars mechanism (that is when the friction gearing blocks contact rigidly), the output force of piezoelectricity ceramic will completely translat
15、es to pretightening force through the flexible four bars mechanism.4. DRIVE CHARACTERISTIC ANALYSIS OF THE MECHANISMStudying and mastering the drive characteristic of mechanism redounds to adopting the proper measures to improve the whole performance and provides the design basis for designing the c
16、ontrol system.4.1 Drive torqueWhen system starts, there is a problem on initial inertia moment as a result of the existence of parts quality. To research the drive torque, choose the friction gearing sleeve as subject investigated. According to the theory that the kinetic energy of gearing train is same before and after conversion, the rotary inertia of each part is transformed to friction sleeve. Because of that, we can get the ro
