Papers by Keyword: Accuracy Synthesis

Abstract: In order to reduce manufacturing cost, a methodology of accuracy synthesis for machine tool was recommended by combining both machining cost and Least Square method. Weighted coefficients representing the machining difficulty of manufacturing processes were introduced. 3PRS/UPS redundant parallel kinematic mechanism (3PRS/UPS PKM) was taken as an example, and its component tolerances were derived by the proposed method. Comparing with conventional method, the component tolerances were allocated reasonably. A further tolerance allocation for spherical and rotational joints was studied in detail. And hence, the producibility of component was improved and the manufacturing cost was reduced. The results showed that the proposed method was capable of producing tolerance allocations economically and accurately.

Abstract: The existence of the non-compensable errors in limited-degree-of-freedom (limited-DoF) parallel kinematic machines (PKMs) affects the accuracy of mechanism and decreases the location capability. A 3-PRS parallel manipulator as an example, this paper formulates the mathematical model of the accuracy synthesis of the manipulator and carries out the accuracy synthesis based on the genetic algorithms, and then obtains the tolerance range of the non-compensable errors in the manufacture and the assembly.

Abstract: According to the inverse solutions of 3-RPS parallel machine tools, the mapping relationship between the geometrical errors built on the 3-RPS parallel machine tools and errors of out posture has been created, then the error model of direct solutions including all the geometrical parameter errors has been built, and this model can be directly used to analyse the accuracy of parallel mechanism. On this basis, the algorithm about error compensation has been proposed. Moreover, accuracy synthesis of 3-RPS parallel machine tools was made respectively in probabilistic synthesis method and extreme synthesis method, and at last these two methods were compared.