Tolerance Synthesis of Higher Kinematic Pairs

摘要

We present a tolerance synthesis algorithm for mechanical systems comprised of higher kinematic pairs. The input is a parametric model of a mechanical system (part profiles and system configuration) with initial tolerance intervals for the parameters. The output is revised tolerances that guarantee correct kinematic function for all system variations. Nominal parameter values are changed when possible and tolerance intervals are shrunken as a last resort. The algorithm consists of a three-step cycle that detects and eliminates incorrect system variations. The first step finds vectors of parameters values whose kinematic variation is maximal. The maximums of the higher pairs are derived by contact zone construction then are combined into system maximums. The second step tests the vectors for correct kinematic function using configuration space matching and kinematic simulation. The third step adjusts the tolerances to exclude the vectors with incorrect functions. The cycle repeats until every vector exhibits correct function. We demonstrate the algorithm on common mechanical systems.