并联机床的平行机构对其静刚度的影响分析

Effect of Parallel Mechanism of Parallel Machine Tool on Its Static Stiffness

为了研究机床静刚度对并联机床性能的影响,以东北大学研制的3-TPT并联机床为研究对象,通过对机床静刚度模型的理论分析,得出了机床静刚度的表达式.利用大型有限元分析软件ANSYS,在机床不同的受力条件下对机床主架静刚度和机床整机的静刚度进行仿真分析,指出了机床刚度的薄弱环节以及平行机构对机床整机的影响.分析结果表明:机床的z向刚度远大于水平方向的刚度;机床整机的刚度远大于机架的刚度,平行机构能使机床的刚度成倍增加,随着平行机构所在位置高度的增加,其z向刚度增大.

Aiming at the effect of static stiffness on the performance of PMT （parallel machine tool）, the 3-TPT parallel machine tool developed by NEU is taken as the target to investigate. Analyzing theoretically the static stiffness model of the machine tool, an expression is given relevantly. Then, the stiffness of both the main frame and the whole machine tool under different forcing conditions are analyzed simulatively using the software ANSYS for large-size FEA, thus showing the low-stiffness positions and the effect of parallel mechanism on the whole machine tool. The simulating result indicated that the stiffness of a machine tool in vertical direction far exceeds that in horizontal direction and the stiffness of the whole machine far exceeds that of the main frame. It implies that the parallel mechanism enables the stiffness of machine tool to be doubled, and that the stiffness increases with the height of the position where the parallel mechanism is laid on.