Theory and Application of Virtual Tolerance Based on Set Concept

doi:10.3901/JME.2019.07.172

Abstract

Abstract: Virtual tolerance is defined as the tolerance that its upper deviation is smaller than lower deviation. In order to abstract the physical meaning of virtual tolerance, the absolute value of the virtual tolerance is the error compensation and the dimensions between the two extreme values is the error compensation range, utilizing a set to elaborate the dimensions with tolerance requirements (virtual tolerance included) between two extreme values and explore the process from quantitative changes to qualitative changes when the virtual tolerance decreases from a positive number to a negative number. The principles of dimensional homogeneity, the existence condition of general formula of dimension chain and the accuracy of tolerance's calculation are introduced to illustrate the necessity of raising the concept of virtual tolerance and the opposition and unification relations between tolerance and virtual tolerance. It has been experimental verified that the definition of virtual tolerance's physical meaning can significantly simplify the analysis and calculation process of assembly dimension chain, which result in a convenient and flexible computation and fulfill parallel analysis between calculation of error and error compensation, which result in a reasonable tolerance distribution. And by getting the general calculation formula of the fake rejects' dimensional interval during mechanical processing, a way to determine fake rejects' dimensional interval-Probability method is conducted, which greatly improved the efficiency when determining fake rejects.

Key words: error compensation, probability method, set expression, tolerance of qualitative change

CLC Number:

TG801

WANG Xiaohui, GUO Shiyi, CHE Dongdong, LAN Guosheng. Theory and Application of Virtual Tolerance Based on Set Concept[J]. Journal of Mechanical Engineering, 2019, 55(7): 172-177.

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