Constrained Degrees Of Freedom Research Articles

A Novel Determination Algorithm of Locating Parameters for Fixture Design

In order to obtain the machining requirements of the machining features, it is necessary to develop a proper fixture locating scheme to constrain correctly the degrees of freedom (DOFs) of a workpart. In this paper, a machining-requirement-based design approach to locating scheme is for the first time created. Firstly, the relationship is established between the machining dimensions and the DOFs to be constrained theoretically. Secondly, the fixture locating scheme is established to characterize practical constrained DOFs of a workpiece in terms of the locator number and positions. As a result, locating correctness is defined according to the relationship between the theoretical constrained DOFs and the practical constrained DOFs, and then the determination algorithm of locating parameters is proposed quantitatively for the first time to design the fixture locating scheme.

A Machining-Dimension-Based Approach to Locating Scheme Design

In traditional and modern manufacturing systems, how to plan the workpiece holding is the first issue of the machining operation to be confronted for the fixture design. To ensure the machining accuracy of specific dimensions, it is necessary to develop a proper fixture locating scheme to constrain correctly the degrees of freedom (DOFs) of a workpiece with respect to the cutting tool. In this paper, a machining-dimension-based locating scheme design approach is developed and partitioned into two main parts for the study. First, the relationship is established between the machining dimensions and the DOFs to be constrained theoretically. Second, the fixture locating scheme is established to characterize the practical constrained DOFs of a workpiece in terms of the known locator number and positions. As a result, judgment criteria are formulated quantitatively for the first time to verify not only the locating scheme correctness but also to identify the cause of locating scheme incorrectness. Finally, two test examples are illustrated to show the proposed locating scheme.