Method for measuring puckered mouth of tube end of steel tube or radial deviation of outer wall of tube body

Abstract

The invention is mainly used for measuring the surface defect of a steel tube, and particularly relates to a method for measuring the puckered mouth of the tube end of the steel tube or the radial deviation of the outer wall of a tube body. In the method, a reference circle is established in a space outside the outer wall of the steel tube, and then the concept of an ideal circle is established, namely the outline of the ideal circle is not in physical contact with the outer wall of the steel tube, so that the puckered mouth size of the tube end or the radial deviation of the outer wall of thetube body can be measured more accurately; meanwhile, the invention provides a method for calibrating the outline of the ideal circle as a relative zero point and measuring the puckered mouth size ofthe tube end or the radial deviation of the outer wall of the tube body on the basis of the relative zero point. Compared with the conventional measuring method, the method for measuring the puckeredmouth of the tube end of the steel tube or the radial deviation of the outer wall of the tube body can avoid manufacturing a large number of ideal circle calibration modules, and is wide in application range, economical and practical.

Description

technical field [0001] The invention relates to a method for measuring the radial deviation of the pout at the end of the steel pipe or the outer wall of the pipe, which is used for measuring the surface defect of the steel pipe. Background technique [0002] Weld seam pouting is a common geometric defect in the manufacture of welded steel pipes for pipelines, and its severity depends on the technical level of steel pipe manufacturing. When the pipe is subjected to internal pressure, the weld beak will generate additional bending stress, and the additional bending stress and the film stress generated by the internal pressure will be superimposed, and stress concentration will occur at the beak part of the inner surface of the pipe, resulting in a decrease in the bearing capacity of the pipe and an increase Susceptibility to stress corrosion cracking, reducing fatigue life. At the same time, the existence of this defect is not conducive to the butt joint of the pipe ends in ...

AI Technical Summary

Problems solved by technology

Since the principle of this method is to assume that the arc part of the tool is completely in close contact with the outer wall of the steel pipe, and the arc of the outer wall of the steel pipe in the fitting part is an ideal arc, this can be judged by the gap between the bottom surface of the groove in the middle of the formwork and the weld toe of the weld seam The size of the pout, but in reality, in the production of steel pipes, due to the limitations of the steel pipe manufacturing process, the circumferential section of the steel pipe is not an ideal circle, or even a regular shape, and it is impossible to fit the template when measuring at any position It fits ideally with the arc of the outer wall of the steel pipe. Therefore, it is difficult to keep the arc of the outer wall of the steel pipe consistent with the ideal arc. Therefore, the precondition of using the template method is basically inconsistent with the actual situation, and the measurement accuracy cannot be guaranteed.

[0012] (2) According to the measurement principle of this method, when measuring the pout at any point within 50mm on both sides of the weld, it is necessary to move the center of the template to directly above the diameter of the point, and the position of the template will change, which will cause If the fit of the outer wall of the steel pipe changes, the measurement results of the pout at any two points are not comparable, and there is a problem with the relative accuracy

[0013] (3) According to the process characteristics of steel pipe production and manufacturing, the circumference of the pipe end of the steel pipe is not unique, but there are a large number of different pipe end circumferences, and there may be large differences

[0018] (1) This tool method uses a standard arc (ideal arc) module for calibration, that is, the principle is that three points are in the same circle to form an ideal arc in space, and then measure the size of the pout, but in actual measurement, two The radius at the fulcrum is basically different from the ideal arc radius, so the measurement basis has changed, and the measurement results will be inaccurate

[0019] (2) Since this method also uses the measurement of the center position of the support to determine the size of the pout, the measurement of the pout at any point within 50mm on both sides of the weld requires the movement of the measuring tool. Changes in position and different pipe diameters at the fulcrum will reduce the accuracy of the measurement, and the measurement results of the pout at any two points are not comparable

[0020] (3) It is also necessary to make a large number of standard arc modules for calibration, which is also very uneconomical

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