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The cause of uneven wall thickness of carbon steel seamless steel tube
Jan 29, 2019

Based on a plug mill rolling after anatomical analysis of carbon steel seamless steel tube, think perforation capillary after plug mill rolling, longitudinal and carbon steel seamless steel tube wall thickness uneven remain largely in the form of the perforation thickness uneven distribution of MAO, the carbon steel seamless steel tube still have after rolling spiral of uneven thickness, and the transverse uneven wall thickness increased significantly.The reasons for the uneven wall thickness of automatic tube rolling mill are as follows: (1) the form and severity of the uneven wall thickness of perforated capillary tube directly affect the form and severity of the uneven wall thickness of seamless steel tube of carbon steel after rolling.(2) in the automatic rolling mill on the pipe, because the rod bending, so that the top position deviation from the center of the hole and lead to uneven wall thickness, the tube and tube head on the cross section of the maximum wall thickness and minimum wall thickness position is almost fixed;However, the uneven degree of wall thickness from the end of the pipe to the end of the pipe increases gradually. Therefore, reducing the residual bending degree of the ejector rod and the axial force of the ejector rod during pipe rolling can significantly reduce the uneven degree of wall thickness.(3) the greater the wall reduction, the more serious the uneven wall thickness of waste pipe, the less the wall reduction, the automatic tube rolling machine has the effect of reducing the uneven wall thickness of perforated pipe.(4) hole adjustment is not correct, when the roll seam uneven, will make the wall thickness of the pipe uneven aggravation.


For seamless carbon steel seamless steel tube mill Φ 400 mm automatic tube rolling unit, perforation, secondary perforation (extension), automatic tube rolling and rolling process are the four tubes measured wall thickness data of Fourier transform, it is concluded that the quantitative analysis of uneven wall thickness and its forming reasons, and on this basis, put forward for improving the carbon steel seamless steel tube wall thickness uneven way:(1) the distribution characteristics of the helical wall thickness uneven on the pipe after secondary perforation (extension) remain to the finished pipe, so improving the secondary perforation (extension) is the key to improve the precision of the finished pipe wall thickness, the main measure is to improve the tool design, improve the concentricity of the rod and the top and the rolling line in the rotation process.(2) improve the wall thickness of the capillary after perforation is an important part of the uneven, the main measure is to improve the heating uniformity of tube billet, improve the precision of centering hole, lengthen the length of the top of the entire belt and the length of the cone, improve the concentricity of the rod and the top in the process of rotation and rolling line.(3) rolling pipe will produce serious symmetry wall thickness, but to reduce the spiral wall thickness has a certain role.Therefore, should be rolling two tube rolling, lane between tubes should be turn 90 °.(4) the whole process can basically eliminate the symmetry wall thickness inequality, but to eliminate the role of the spiral wall thickness inequality is very small, therefore, should improve the ability of the whole machine.Fourier transform is an effective method to study the uneven wall thickness in the process of oblique rolling.