Precision CNC screw grinder dynamic / static / thermal characteristics analysis and optimization
|School||Nanjing University of Technology and Engineering|
|Course||Mechanical and Electronic Engineering|
|Keywords||Nut grinding machine dynamic/Static/thermal characteristics FEA StructuralOptimization Combination interface Whole machine|
The good performance of precision CNC nut grinding machine is the premise and basis to process high quality ball screw pair of nut. The nut grinding machine is required not only to have good static property but also to have good dynamic property.This paper is based on the ANSYS software and sets CNC internal thread grinding machining center as the research object, analyse static, dynamic, thermal characteristics of key parts and whole machine and make structure optimal design. Modal test is also be made for grinding rod.Aiming at improving the vibration resistance ability to avoid the possible resonance of the structures and reducing the weight as much as possible, this paper carries out the dynamic analysis on three key parts—bed, head frame and table. First identify the weak parts of the structures, establish various improvement schemes, and then choose the optimal scheme by contrast method. The first natural frequency of the bed increases by16.7%and the weight reduces by1.36%.Meanwhile, the maximal deformation decreases22.1%and stress distribution is even. The optimal schemes of head frame and table.all reach the anticipated goal. Grinding rod is studied by the FEM and the dynamical experiment. Natural frequency comparison between the results shows that the error is very small. It proves that the finite element model reflects the actual mechanical structure very well.The table of the grinding machine drives by linear motor. Considering the effect to the table exerted by the hot source,rolling guide friction and linear motor,ANSYS finite element analysis software is used to do thermal-mechanical coupling analysis on the table. The results show that the temperature in steady state of up-table is3℃and the maximum deflection is35.2μm.Joint surface affects the static and dynamic characteristic of the whole machine greatly. The machine’s three main combination interfaces were simulated and their parameters were identified by Yoshimura method. Then the dynamic performance of the whole machine was analyzed. The study through key parts structure optimization and combination interface’s parameters optimization found that structure optimization of the key parts plays a minor role in the dynamic performance of the whole machine, but dynamic performance of the joint surface parameters optimized machine is improved greatly, and the possibility of the resonance phenomenon is reduced greatly.