Plane shape error evaluating method aiming at precise assembling and based on entropy theory

Abstract

The invention discloses a plane shape error evaluating method aiming at precise assembling and based on entropy theory. The surface of a part is measured; heights of all measuring points are taken as probabilities of all possible values of random variables; with the combination of the characteristic that the uniformity of occurrence probability of all possible values of the random variables can be evaluated, the plane shape error distribution uniformity is subjected to overall primary evaluation by using entropy functions; if the evaluation result shows that the influence of the shape error of a plane on assembling precision cannot be overlooked, the plane is further subjected to salient point and contact concave search, and the salient point heights, the position distribution uniformity and the contact convex area gentle degree are respectively evaluated, thereby establishing comprehensive evaluation indexes of the plane shape error distribution uniformity and accordingly evaluating the plane shape error of the precise assembling. By utilizing the method, the relationship among the plane shape error distribution uniformity, the assembling precision and the stability is revealed, and guidance for improving the assembling precision and optimizing assembling process is provided.

Description

technical field [0001] The invention relates to a plane shape error entropy theoretical evaluation method for precision mechanical system assembly, which belongs to the field of manufacturing quality prediction and control. Background technique [0002] Evaluation of shape error is the basis for determining whether the machined parts meet the tolerance requirements. At present, the most commonly used traditional shape error evaluation method is the minimum area method. The minimum area method refers to the use of two ideal features to envelop the actual features, and the distance between the two ideal features is minimized by adjusting the direction of the two ideal features. At present, the evaluation of shape error using the minimum area method can be roughly divided into the following categories: linear programming method, algorithm based on computational geometry and method based on feature points. The goal of the above method is to obtain the shape error value of the ...

AI Technical Summary

Problems solved by technology

[0003] However, in the precision mechanical system, although the error value obtained by the traditional evaluation method of the shape error is the same, the different shape error distribution will lead to different contact states between the mating surfaces

As a result, due to the transmission and accumulation of shape errors, different assembly errors are caused

In addition, non-uniform contact caused by shape error distribution usually causes parts to generate non-uniform stress field. With the change of time, temperature and mechanical environment, the energy of non-uniform stress field will be released, which will change the assembly accuracy.

Studies have shown that for mechanical systems with low precision requirements, the impact of shape errors on assembly accuracy is not significant, but for precision mechanical systems, shape errors will have a significant impact on assembly accuracy

Traditional shape error evaluation methods cannot reveal the influence of shape error distribution on assembly accuracy

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