Fast Detection and Compensation Method of Machining Error Based on Nurbs Surface

Abstract

The invention discloses a machining error rapid detection and compensation method based on an NURBS curved surface. The method comprises the steps that a designed NURBS curved surface is analyzed, and a series of characteristic points are selected as a sequence P to be measured; according to a machine tool processing curved surface applied to the designed NURBS curved surface, points to be measured in the sequence P to be measured are measured to acquire an actually measured sequence Q'; the deviation between the actually measured sequence Q' and the sequence P to be measured is computed; if the deviation is less than or equal to the machining accuracy, adjusting is not needed; if the deviation is greater than the machining precision, the sequence P to be measured is adjusted according to the deviation to acquire a compensation sequence W; 4) a control point C is adjusted according to the compensation sequence W to acquire a compensation curved surface; and machining is carried out according to the compensation curved surface to acquire a machining curved surface, wherein the error between the machining curved surface and the designed NURBS curved surface is small. According to the method provided by the invention, the efficiency of the detection of an on machine measurement method on the machining accuracy of a free curved surface is improved, and compensation machining can be carried out on the free curved surface.

Description

technical field [0001] The invention relates to the field of machine tool processing, in particular to a fast detection and compensation method for processing errors based on NURBS curved surfaces. Background technique [0002] With the development of industries such as aviation, automobiles and molds, free-form surfaces are more and more widely used in part design, and the processing of free-form surfaces has higher requirements for precision and efficiency. In order to improve the machining accuracy of free-form surfaces, it is generally necessary to measure, evaluate and compensate for machining errors. The characteristics of non-rotational symmetry, irregular shape, and irregular structure of free-form surfaces make the measurement of free-form surfaces very complicated. Rapid and precise measurement and evaluation of the machining error of free-form surfaces is of great significance for machining high-precision free-form surfaces. [0003] The measurement of free-form ...

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Problems solved by technology

[0005] Method 1 can obtain the processing error of the surface by measuring a large number of points on the surface, and then comparing it with the ideal CAD model, but due to the large number of measured points, the measurement efficiency of the entire surface will be relatively low

Method 2 is similar to method 1, except that the surface shape error data is obtained directly in each measurement, which avoids the later data processing and error analysis of massive measurement data, and can improve the measurement efficiency to a certain extent, but there are still disadvantages of method 1. A large number of measurement points makes the measurement inefficient

Method 3 chooses to measure the characteristic line of the curved surface. This method requires a small number of measurement points, but this can only test whether the accuracy meets the requirements, and cannot measure the specific processing error of the curved surface.

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