PROBLEMS OF FREE ROLLING OF THE PILGER HEAD AND WAYS OF THEIR SOLUTION

S. L. Stasevsky, V. F. Balakin, Yu. D. Ugryumov

Abstract


A feature of the process of hot pilgring rolling of pipes is the presence of an under-roll of the rear end of the sleeve, which forms the so-called pilger head, which is due to the presence of a front support on the sleeve from the mandrel head of the feeding apparatus. Pilgerghead refers to the technologically inevitable loss of metal in the pilger mill, especially when rolling thin-walled (D / S = 12.5 - 40) and especially thin-walled (D / S > 40) pipes. At the same time, when rolling thick-walled pipes (D / S = 6-12.5), in practice, the methods of butt-end rolling of sleeves and free rolling of the pilger head are used, and the latter is used quite limited and only as an addition to the butt-to-butt rolling method of the last sleeve in a batch or in case of disturbance this process. The presence of a pilger head is one of the main factors of increased metal consumption at pilgrim mills. The analysis of the problems of the process of free rolling of the pilger head is carried out and the ways of their solution are proposed. One of the main problems of this process is the impossibility of its use when rolling out thin-walled (D / S = 12.5-40) and especially thin-walled (D / S > 40) pipes, which is due to the peculiarities of removing the pipe from the mandrel using a gate device and a feeder.

To solve this problem, a new technology has been proposed, which provides for rolling the pilger head to such a wall thickness at the end, which ensures the removal of thin-walled (D / S = 12.5-40) and especially thin-walled (D / S > 40) pipes from the mandrel. New solutions have been proposed to reduce the displacement of the roll along the mandrel in the first rolling cycles of the pilger head, the theoretical study of which made it possible to recommend a method of reducing the speed during its rolling in comparison with the steady-state process by 40-50%, as the simplest and most effective. Two new methods have been proposed for removing the pipe from the mandrel after full or partial rolling of the pilger head, the first of which is distinguished by the simultaneous convergence of the upper and lower gates, and the second - by holding the rolling by the press dies. To hold the mandrel ring at the mandrel head, two new solutions have been proposed, according to the first, permanent magnets are mounted in the ring, according to the second, both halves of the ring are connected using Belleville springs, which create the necessary adhesion to the mandrel.


Keywords


pilger mill; pipe; Pilger head; mandrel; metal loss

References


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DOI: https://doi.org/10.31319/2519-2884.tm.2020.2

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Copyright (c) 2020 S. L. Stasevsky, V. F. Balakin, Yu. D. Ugryumov

ISSN (print) 2519-2884

ISSN (online) 2617-8389