A Method for Determining the Sectional Profile Curve of Large Plastic Bending of Thin-walled Pipe

Abstract

The invention belongs to the technical field of metal pressure processing and provides a method for determining the large plastic bending section profile curve of thin-walled pipes. The method mainly includes the following steps: 1. Use image detection means to obtain the contour image of the cross-section of the thin-walled tube after bending and flattening; 2. Detect the outer edge of the flattened contour based on image processing technology and obtain the pixel coordinates of the contour points; 3. The least squares circle method is used to determine the centroid of the pipe section before deformation, and then the edge image is coordinately translated; 4. Four forms of functions are used in sequence to perform curve fitting on the pixel coordinates of the contour points, and the horizontal direction of the pipe can be determined based on the fitting results. The profile curve of the section. This method can effectively control the flattening deformation of the thin-walled tube section after large plastic bending, and achieve quantitative evaluation of the quality and accuracy of the bent tube section.

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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