| The gantry rack is the most important support component of parallel numerical control C shape milling machine.The gantry rack’s design quality affects the performance of the machine greatly.This paper makes a research of designing and optimiziting the gantry rack of parallel CNC milling machine.Firstly, preliminary gantry frame conception has been thought out according to new parallel milling’s conception design and technique parameters. then the geometrical parameters are difined and kinematics model of the machine is analyzed.Based on the given working parameters, load conditions and maching characteristics the stress of connections of frame with three groups of double electric cylinder hinge under the four different load conditions is calculated.Secondly,the main parameters of gantry rack are decided preliminarily, then the gantry rack’s characteristics are analyzed.After this,the idea about the whole frame and detailed inner structure is prompted. the3D model is established by using Pro/E.Thirdly, the finite element static analysis of the gantry rack under the4different load conditions is done,next the weak areas are improved according to the analysis results, then the same analysis is done repeatedly until the gantry rack’s stiffness become reasonable.Finally, on the basis of meeting the static stiffness condition, the dynamic stiffness analysis is done. the first six modals which affect machine’s overall performance are obtained,and the dynamic performance of it is assessed,then suggestions about how to avoid the frequency of the excitation force under multi-tooth tool machining condition are proposed.The research result of this paper provides the reliable basis and reference for the subsequent project research and the prototype development. |
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