并联机床的灵巧度评价指标及其应用

Dexterity measures of parallel machine tool and its application

研究了并联机床的灵巧度评价指标及其在实际加工中的应用。介绍了一种新型的五自由度并联机床,该机床机构具有五个驱动分支和一个约束分支,可以实现三维移动和二维转动。建立了该机床机构的雅可比矩阵,得到了三个影响机床机构灵巧度的指标,即条件数、最小奇异值、可操作性;并通过对这三个并联机床灵巧度评价指标进行分析,定义了两个灵巧度的综合评价指标-综合灵巧度系数和综合灵巧度,分别作为评价不同位形下灵巧度和整个刀位文件灵巧度的指标。最后,介绍了在实际加工中对不同加工轨迹的灵巧度进行综合评价的方法。实验结果表明:机床实际加工100平面圆,对各向同性有较高要求时的最优加工轨迹为z=650 mm,保证了机床加工过程中应具有良好运动和动力学性能的要求。

In order to study on dexterity measures of parallel machine tool（PMT） and its application in real processing, a novel 5 Degrees of Freedom （DOF） fully PMT consisting of five actuating limbs and one passive constraint limb is introduced, and its Jacobian matrix is established. The Jacobian matrix is used to define three dexterity measures： conditional number, the smallest singular value and operation. By analyzing three dexterity measures of parallel machine tools, two terms named comprehensive dexterity coefficient and comprehensive dexterity degree are defined to evaluate the dexterity of various configurations and whole cutter location file respectively. Finally, the method for evaluating the dexterity under various tool trajectories is introduced. Experimental results indicate that a relatively optimal trajectory z is 650 mm with a higher isotropy in real processing of circle（radlus as 100 mm）. It can satisfy the machine requirement of performance of motion and dynamics.