| Summary: | 碩士 === 國立交通大學 === 工學院精密與自動化工程學程 === 99 === With advance in technology, the precision and accuracy of machine tools and manufacturing processing have improved significantly, meeting the requirement of modern applications. The thermal distortion error still affects the accuracy of machine tools, accounting for a large proportion of dimension error. There are many reasons for the spindle thermal distortion error such as friction heat of spindle rotation and spindle axis moving at bearing, spindle motor electrical driving, spindle cooling strategies, etc.
Methods to overcome the spindle thermal distortion can be divided into active and passive approaches:
Active approach is meant by effort spent on minimizing thermal distortion at the design stage of machine, assisted by the finite element analysis software, simulating the heat distribution of the machine, reducing the effect of heat source on machine. With consideration of reducing the effect of heat generation, heat convection and heat conduction in mind, materials of low thermal conductivity, conductivity should be used . Previous studies have, proposed to replace the traditional grey iron casting with marble, ceramic ball bearing with steel ball bearings and etc.
Passive approach is by means of using mathematic model to predict the influence of the spindle thermal deformation error for the axial distortion. Then compensates it to decrease the error. If cost is under consideration, active approach takes more money and developing time than passive approach. Active approach depress the influence of heat source. On the contrary, the passive one is to compensate the error which is generated by the heat. Both of them is discussed by many theses and references.
In this thesis, with considering developing time, cost and without making changes in mechanical design of the machine, a general mathematic model of spindle thermal deformation is constructed to predict the error and compensates in real time, Check the result on the machine with variation spindle speeds and under to control the heat deformation of Z and X direction in 20 μm.
|
|---|
