| The ultra-precision positioning stage is use of the macroµ-drive technology to meet the high-speed and precision positioning requirements. During operating, the positioning accuracy of the ultra-precision positioning stage depends onthe accuracy of chuck(micro-stage). But the gravity of chunk and its load, andthe disturbance of system actuators and ground caused by noise limits the precision accuracy of the ultra-precision positioning stage. To solve these problems, a gravity-compensationand local vibration isolation technology of chunk is developing.The principle of technology is flotation or magnetic levitation to compensatinggravity and achieving horizontal and vertical low stiffness to prevent disturbance,and the vertical drive motor in Lorentz law to realize the movement of chunk.Research on the gravity compasation and vibration absorber of ultra-precision positioning stage will provide a high-precision positioning with strong protection.This paper summarizes the analysis of gravity compensation and vibration isolation technology in ultra-precision positioning stage from the research institute local and abroad. On the basis of that, the function and indicators of magnetic compensator is determined and according it the structure of magnetic compensatoris designed in detail. Computer simulation and experiments is taken to verifyingthe indicators. Specific content includes:1.On the basis of the macroµ-drive technology and vibration analysisof a single degree of freedom system, the magnetic compensator functions and indicatorsis determined. And it proposed a magnetic compensator design, the useof permanent magnet pole reach a permanent magnet structure design. According to the vertical motor characteristics, a Lorentz actuator structure is designed.And according to the experimental conditions，the water-cooled structures is set up.2. According to the design parameters of the magnetic compensator indicators, the permanent magnets based on the equivalent current density model is established, achieving the strength and stiffness calculations of permanent structure. And the heat of coil while operating is carried out theoretical derivation and calculation.3. Using a Solidworks3D CAD software for magnetic compensator to builda three-dimension modeling, and the use of IES boundary element electromagneticanalysis software, the magnetic compensator parameters such as strength and stiffnesssimulation analysis is accomplished. The maximum static force of magnet A (655Aturns). The range of vertical stiffness is from-259to+260N/m (stroke is from-1to+1mm), which provides the reference data for subsequent experiments.4.Built a experimental of mechanics measurement and a temperature measurement system for magnetic compensator to test the mechanical properties and thermal performance. Experimental results show that the maximum static force of magnetic compensator is77.45N, and the range of dynamic force is from-19.67to+14.75N (which the range of current is from-6to+6A).The motor constant is2.69N/A (655Aturns).The range of vertical stiffness is from-233to+252N/m (the stroke is from-1to+1mm). the calculation and simulation results are consistent, which meets the indicator.In this issue, magnetic compensator is able to achieve a compensation function, and has a low vertical stiffness for vibration isolation and a driven functionality. The experiment results meet the indicator. In the situation of the load whichis76N, the range of dynamic force from-20to+20N, and the range of vertical stiffness from-233to+252N/m, the magnetic compensator for ultra-precision... |
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