Method for determining large-plastic bending section profile curve of thin-walled pipe

Abstract

The invention belongs to the technical field of metal pressure processing, and provides a method for determining a large-plastic bending section profile curve of a thin-walled pipe. The method mainlycomprises the following steps: 1, acquiring a contour image of the cross section of a curved and flattened thin-walled pipe by means of the image detection means; 2, detecting the outer edge of the flattened outline based on the image processing technology and acquiring the pixel coordinates of contour points; 3, determining the centroid of the pipe section of the thin-walled pipe before deformation through the least square circle method, and carrying out coordinate translation on the edge image; 4, through successively applying four form functions, carrying out curve fitting on the pixel coordinates of contour points, and finally determining the contour curve of the cross section of the pipe according to the fitting result. According to the method, the flattened deformation amount of thecross section of the thin-walled pipe after the large-plastic bending of the thin-walled pipe can be effectively controlled. Meanwhile, the quantitative evaluation on the quality and the precision ofthe cross section of the bent thin-walled pipe can be achieved.

Description

technical field [0001] The invention belongs to the technical field of metal pressure processing, and relates to a method for determining the contour curve of a large plastic bending section of a thin-walled pipe, which is applied in a large plastic bending process of the thin-walled pipe and can accurately determine the profile curve of the large plastic bending section of the thin-walled pipe. Background technique [0002] In recent years, the demand for high-precision thin-walled metal pipes has risen sharply in the fields of industry, military, aerospace, petrochemical and other fields. During the production and service of thin-walled pipes, they often bear large plastic bending loads, making the cross-section of the pipes Flattening deformation occurs under the combined action of compressive stress in the inner bending area and tensile stress in the outer bending area, which reduces the stiffness and subsequent deformation capacity of the pipe, and affects the section ac...

AI Technical Summary

Problems solved by technology

This is mainly due to the fact that there is a large bend in the axial direction of the pipe after deformation, making it difficult to measure the position of the outer contour point of a certain cross-section after flattening by using the traditional mechanical measurement method to scan and measure in the circumferential direction.

Therefore, qualitative assumptions and estimates of section flattening are often made using known similar simple geometric shapes, resulting in a large difference between the estimated value and the actual value, and the actual flattening exceeds the allowable value, which brings safety hazards to the use of pipes

Just like thin-walled pipes as the basic unit of large structural parts, once a quality defect in a certain unit will cause the instantaneous collapse of the entire system components

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