Control method of stretch-reducing mill steel tube thickening terminal

Abstract

The invention relates to a chipping control technique of head and rear thickened ends of a steel tube which is used in a stretch reducing process of a seamless steel tube. A control method of the thickened ends of the steel tube of a stretch reducing machine computes a control factor table of the thickened ends of the steel tube according to the thickness distribution rule of tube end walls of the stretch reducing machine, and by utilizing the factor table, the control method can adaptively increase and decrease the number of machine frames that participate in the CEC action according to the length change of the thickened ends in the rolling process, and realize the shortening of the head and rear thickened ends by coordinating with the adjustment of additive tension that acts on the head and rear thickened ends of the steel tube; the computation of the CEC factor table of the stretch reducing machine comprises the following steps: a basic speed governing level and a largest speed governing level are determined according to average tension; original CEC speed governing factors are computed according to the working diameter change of a roller; an original CEC speed governing factor table is constructed; the number of the machine frames that simultaneously participate in the CEC action in each machine frame position is determined according to the extensibility of the steel tube; the original CEC factor table is revised by combining with the number of the machine frames that simultaneously participate in the CEC action in each machine frame position. The chipping control technique of the head and rear thickened ends of the steel tube can effectively shorten the length of the thickened ends of the steel tube and improve the steel tube yield.

Description

technical field [0001] The invention relates to a Crop End Control (CEC for short) technology of a steel pipe head and tail thickened end cut loss control (CEC) in a tension reduction process of a seamless steel pipe. Background technique [0002] The wall thickness change of the steel pipe in the tension reducer is realized by adjusting the tension of the steel pipe between the racks, and the tension between the racks is generated by the speed difference between the rolls. The thickening phenomenon at the end of the steel pipe is a characteristic phenomenon of tension reduction. The thickening of the pipe end is generally considered to be caused by the fact that when the head and tail of the steel pipe pass through the tension-rising and tension-decreasing racks during the rolling process, the tension it bears is smaller than the stable rolling state between the tension-invariant racks. Therefore, the idea of ​​steel pipe thickening end control (hereinafter referred to as ...

AI Technical Summary

Problems solved by technology

[0004] During the rolling process, the thickened end of the steel pipe head and tail actually grows continuously as the steel pipe advances in the rolling mill. Only a few fixed racks are used to perform CEC on the thickened end. The consequences are: on the one hand, the effect Too many racks will affect the CEC to the normal end of the steel pipe. On the other hand, too few racks will not achieve the effect of shortening the thickened end.

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