基于刚体运动学的工件自由度分析方法

Analysis Method of Workpiece Degree-of-Freedom Based on Rigid Kinematics

夹具设计最主要的任务就是将工件精确定位。在定位过程中,首先必须合理地约束工件自由度;其次在自由度受到约束的方向上,工件也只能在规定的范围内变动。因此,分析工件的自由度约束情况是复杂定位方案设计甚至整个夹具设计的关键所在。基于刚体运动学,文章建立了定位原理的数学模型,以定量分析工件自由度的约束情况。从而使得传统的定位原理从定性描述上升为数学定量表示,为计算机辅助夹具设计系统的开发提供了基础理论,并首次在UG软件系统环境下实现了夹具约束工件自由度分析系统的二次开发。

The most important task of fixture design is to locate a workpiece in the precision position. First, degrees of freedom （DOFs） of a workpiece must be soundly constrained during the locating operation. Second, the workpiece can only translate and rotate within specified limitation in the direction of constrained DOFs. Therefore, to analyze the constraint of DOFs of the workpiece is a key consideration of designing the locating scheme and in turn, the entire fixture configuration. Based on the rigid kinematics, the locating principle is formulated in this paper. Thus, the locating principle is developed from qualitative description to quantitative formulation, and it provides the theoretical basis of developing CAFD （computer aided fixture design） system. Therefore, the analysis system of DOF of the workpiece is for the fast time developed within the UG system.