Method for evaluating minimum area of line profile error of cross section of skirt part of variable-ellipse piston

Abstract

The invention discloses a method for evaluating a minimum area of a line profile error of a cross section of a skirt part of a variable-ellipse piston. The method comprises the following steps of: measuring and acquiring a coordinate of a measurement point on the cross section of the skirt part of the variable-ellipse piston at first, if the coordinate of the measurement point is a rectangular coordinate, converting the rectangular coordinate into a polar coordinate, and establishing a model for evaluating the minimum area of the line profile error of the cross section of the skirt part of the variable-ellipse piston; then randomly producing an initial position and an initial speed of a particle, calculating a target function value of the particle according to the initial position of the particle and a measured value of the cross section line profile, and determining a partial optimal particle and a whole optimal particle; and modifying the speed of the particle and changing the position of the particle by an enrichment factor method, updating the position of the particle optimal particle and the position of the whole optimal particle by using the changed position of the particle, and when a predetermined terminating condition is achieved, outputting a minimum area answer, the optimal parameter value and the ovality of the line profile error of the cross section of the skirt part of the variable-ellipse piston. By the method, the minimum area answer, the optimal parameter value and the ovality of the line profile error of the cross section of the skirt part of the variable-ellipse piston can be calculated at the same time.

Description

technical field [0001] The invention relates to a line profile error evaluation method, in particular to a method for evaluating the minimum area of ​​line profile error in the cross-section of a variable ellipse piston skirt, belonging to the field of precision measurement and computer application. Background technique [0002] The size of the shape error is very important to the product quality and its service life, and it is of great practical significance to realize the rapid and accurate evaluation of the shape error. There are many methods for evaluating shape error. Taking the evaluation of straightness error as an example, the evaluation methods include the minimum area method, the least square method, and the method of connecting two ends, but the results obtained by various methods are not the same, and even vary greatly. It will lead to misacceptance or waste of the product, which will directly affect the quality and cost of the product. Therefore, both the intern...

AI Technical Summary

Problems solved by technology

Due to the complexity of the shape of the variable ellipse piston, the evaluation of its geometric shape accuracy has become a difficult problem

However, the existing evaluation methods for the profile error of the cross-section line of the variable ellipse piston skirt all use the least squares method. Since the least squares method only provides an approximate evaluation result of the shape error, it does not guarantee the minimum regionality of the solution. According to the least squares method The calculated result is 1.8% to 30% larger than the result obtained by the minimum area method, and the average overestimation is 10%, so it is not suitable for the evaluation of precision and ultra-precision parts

[0004] Based on the above analysis, the main shortcomings of the current research work in related fields are: the lack of an efficient and accurate method for evaluating the profile error of the cross-section line of the variable ellipse piston skirt

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