A Discrimination Method for Geometric Feature Changes Before and After Engineering Changes of Sheet Metal Parts

Abstract

The invention proposes a method for discriminating the change of geometric features before and after engineering modification of a sheet metal part, and determines the comparison elements (topological line, cross-section contour line and discrete point of the shape surface) of the two models. First use the topological line as a comparison element to compare the geometric features of the design model before and after the change to judge the changed part, and mark the corresponding topological line whose length deviation exceeds 0.001mm. If the topological line cannot clearly mark the changed features, then use the length of the model section contour line or the thickness dimension as the comparison element for further comparison. For frame ribs and profile parts, the model section contour line is used as the comparison element, and the mark length deviation exceeds 0.001mm corresponding section outline. For wall panels and skin parts, the thickness dimension of the model is taken as the comparison element, and the discrete points where the thickness value deviation exceeds 0.001mm are marked. Finally, the change location is judged according to the marked topological line and the marked cross-sectional contour line or discrete points.

Description

technical field [0001] The invention relates to the technical field of mechanical processing, in particular to a method for discriminating geometric feature changes before and after engineering modification of sheet metal parts. Background technique [0002] Sheet metal parts are the main part of the modern aircraft body, which directly affects the shape accuracy and structural bearing capacity of the aircraft. Sheet metal parts have the characteristics of many varieties and few quantities, complex structures, large outer dimensions, and low rigidity. Their manufacturing is an important link that determines the overall performance of the aircraft, and their digital manufacturing is the key to the digital manufacturing of aircraft. [0003] Engineering changes are unavoidable during the development of an aircraft due to design improvements and the use of new materials. Complex sheet metal parts have various structures, product design and forming processes are complex, and ch...

AI Technical Summary

Problems solved by technology

Complex sheet metal parts have various structures, product design and forming processes are complex, and changes are difficult and long-term

Different engineering changes have different influences on the manufacturing model and in different ways. In the process of derivation from the design model to the manufacturing model, those data structure changes related to the derivation will inevitably affect the manufacturing model, and the position of the design change can be quickly and accurately judged. The size and size are the prerequisites for the change of the manufacturing model, which determines the cycle and accuracy of the change. The current method of the manufacturer is usually to place the model before and after the change at the same coordinate position in space and set different colors, and manually observe the two models to determine the change information. The process cumbersome and error-prone

Images