Automatic Numerical Method Of Tolerance Factor Sensitivity Based On The CPVM Model

Sensitivity analysis,whose result can be taken as an reference for tolerance design,is significant intolerance analysis.Reasonable tolerance allocation is vital to the optimization of the product design,the reduction of manufacture costs and the improvement of the product quality.Sensitivity describes the influence of variations of the middle key features on the final error of the target feature.Automatic calculation of sensitivity is an important part in automatic tolerance analysis.This paper proposes the calculation method of sensitivity.Homogeneous matrix is used to represent the affect of relevant feature variations to the positioning processes.Calculation module of sensitivity is added to the 3-D Tolerance Analysis Prototype Software.Numerical calculation of sensitivity is the object function's derivation of variables of relevant features.This papter mainly involves the following parts:1.The first section introduces the research status of sensitivity analysis.Combined with tolerance analysis method,calculation method and correlation formulas is summarized in this part.Shortcomings are discussed together with the above methods.At last,this part describes the background and significance of the study,main research contents and innovation points.2.Part two proposes the determination method of the representing function of the location of the target feature.Based on the error transformation relationship of geometric feature,taking coordinate transformation matrix as mathematical tools,this section introduces coordinate transformation processes from the frame to the target feature and corresponding matrix to get the aim function.3.Position parameter of relevant features is defined in section three.Position parameter is used to describe the position variations of middle features.The influence of posistion variations on the target feature is related to the geometric type,tolerance type,positioning processes,datum order of the relevant feature.Making a classification of the above factors,this section uses matrices involving position parameters to describe the influence mentioned above.These matrices,deviations of position parameters are also shown in this part.4.The forth section proposes theoretical methods of the calculation of the sensitivity value and related logic diagram which consists of filter rules of the error transformation path,location representation function corresponding to the path,determination of the sensitivity matrix and the calculation formula of the sensitivity value referring to the marix.5.Part five introduces the computational process of sensitivity values with an assembly example and the automatic calculation program of sensitivity values.Taking the tolerance analysis prototype software based on the Controlling Variation Point Model as the foundation,automatic calculation module is add to the prototype software.