Causes Of Uneven Wall Thickness In Carbon Steel Seamless Pipes

According to the anatomical analysis of the carbon steel seamless pipe after rolling in the automatic tube mill, it is considered that after the perforated capillary tube is rolled by the automatic tube mill, the longitudinal and transverse wall thickness of the carbon steel seamless tube basically remains in the form of perforated capillary wall. The unequal distribution characteristics, that is, after the rolling of carbon steel seamless steel pipe still has a spiral wall thickness uneven, and the uneven lateral wall thickness increases significantly. The reasons for the unequal wall thickness caused by the automatic tube mill are as follows: 1 The existence and severity of uneven wall thickness of the perforated capillary tube directly affect the existence and severity of uneven wall thickness of thecarbon steel seamless pipe after rolling. 2 When the pipe is rolled on the automatic pipe mill, the maximum bar thickness and the minimum wall thickness are almost constant in the pipe and the cross section of the pipe head due to the bending of the jack, which causes the position of the jack to deviate from the center of the hole type, resulting in uneven wall thickness. No change; however, the degree of inhomogeneity in the wall thickness from the end of the pipe to the pipe is gradually increased. Therefore, reducing the residual bending of the ejector pin and reducing the axial force of the ejector pin during the pipe rolling are significant for reducing the uneven wall thickness. effect. (3) The larger the wall-reducing amount is, the worse the wall thickness is, and the smaller the wall-reducing amount is, the smaller the wall thickness is, the smaller the wall thickness of the perforated capillary tube is. 4 Incorrect adjustment of the hole type, when the roll gaps are not parallel, the uneven wall thickness of the waste pipe will be exacerbated.The seamless steel-seamless seamless steel pipe plant of Baotou Steel Co., Ltd. performed a Fourier transform on the actual measured wall thickness data of the?400mm automatic pipe rolling mill, perforation, secondary perforation (extension), automatic pipe rolling, and uniform rolling in four rolling processes. The quantitative analysis of the wall thickness unevenness and the reasons for its formation are presented. Based on this, a way to improve the unequal wall thickness of the seamless steel tube of carbon steel is proposed: 1 The spiral wall thickness on the waste pipe after secondary perforation (extension) is not The uniform distribution characteristics are always reserved to the finished tube, so improving the secondary perforation (extension) is the key to improving the wall thickness accuracy of the finished tube. The main measures are to improve the tool design and improve the top and head during rotation and the rolling line. Concentricity. 2 It is an important part to improve the uneven wall thickness of the capillary tube after piercing. The main measures are to improve the uniformity of heating of the tube blank, improve the accuracy of the centering hole, lengthen the length of the whole head and the length of the reverse taper, and increase the length of the top rod and the head. Concentricity with the rolling line during rotation. (3) Although there will be serious symmetry of wall thickness unevenness in the rolling tube, it will have a certain effect on reducing the spiral wall thickness unevenness. Therefore, when the tube is rolled, two passes should be rolled. Between the passes, the waste tube should be turned 90°. 4 The homogenization process can basically eliminate the symmetry wall thickness unevenness, but it has little effect on eliminating the spiral wall thickness unevenness. Therefore, the capacity of the homogenizer should be improved. 5Fourier transform is an effective method to study the uneven wall thickness during the rolling process. This method can also be applied to the study of uneven wall thickness of other carbon steel seamless pipe production units.

A worker from a steel pipe company, which is located in China.