RU2443484C2 - Large-diameter seamless pipe production - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to pipe rolling, particularly, to methods of producing seamless large-diameter tubes by repiercing mill. Proposed method comprises piercing of heated billet into shell at screw rolling mill, rolling said shell at repiercing mill, burnishing of rough tube and gauging its at lengthwise rolling mill. Note here that billet piercing into shell is carried out at screw rolling mill in two passes with shell diameter-to-wall thickness ratio approximating to 30.

EFFECT: high-quality large-diameter thin-wall tubes.

1 dwg

Description

The invention relates to the field of pipe production, and more specifically, to methods for producing seamless large diameter pipes on aggregates with a mill expander.

A known method for the production of seamless pipes of large diameter, see Italian patent No.20001117, class. B21B 19/08, claimed 05/19/2000, publ. November 19, 2001, which includes rolling out a preheated hollow billet on an expansion mill, running a rough pipe in a screw rolling mill, and calibrating it on a longitudinal rolling mill.

The main disadvantage of this method for the production of large-diameter seamless pipes is that before rolling on the expansion mill, the hollow billet has to be additionally heated to a temperature of 1150-1200 ° C, and a large amount of scale forms on its inner surface. This affects the quality of the pipes produced. In addition, additional heating of the hollow billet before rolling on the expansion mill leads to an increase in the energy intensity of the pipe production process and its cost.

Of the known methods for the production of large-diameter seamless pipes on an aggregate with an expansion mill, the closest in technical essence is the method described in Japanese patent No. 6198312, class. B23B 23/00, claimed 12/14/90, publ. 07/19/94

A method for the production of large-diameter seamless pipes involves piercing a workpiece into a sleeve in one pass on a screw rolling mill, rolling the sleeve on a reamer mill, running a rough pipe in a screw rolling mill and calibrating it on a longitudinal rolling mill.

и не более. Это обуславливается тем, что после прошивки в один проход на стане винтовой прокатки возможно получение качественных гильз лишь с тонкостенностью

. Последующее же максимальное обжатие гильзы по стенке на стане-расширителе не может быть более 50% при подъеме по диаметру до 30%.The main disadvantage of this method is that it allows to obtain high-quality pipes of large diameter with thin-walled

and no more. This is due to the fact that after flashing in one pass on a screw rolling mill, it is possible to obtain high-quality sleeves with only a thin-walled

. The subsequent maximum compression of the liner along the wall on the expander mill cannot be more than 50% when lifting in diameter up to 30%.

The objective of the present invention is to provide a method for the production of seamless pipes on aggregates with an expansion mill, which allows to obtain high-quality thin-walled pipes of large diameter with a ratio of diameter to wall thickness of up to 70.

The problem is achieved in that in a method for the production of large-diameter seamless pipes, including flashing a heated billet into a sleeve in a screw rolling mill, rolling the sleeve in a expansion mill, rolling in a rough pipe in a screw rolling mill and calibrating it in a longitudinal rolling mill, according to the invention, firmware blanks in the sleeve are carried out in a helical rolling mill in two passes with a ratio of diameter to wall thickness of the sleeve up to 30.

требуемые для этого тонкостенные гильзы с

получают благодаря двум прошивкам на стане винтовой прокатки с последующей деформацией ее по стенке на стане-расширителе на 30-50% при подъеме по диаметру до 30-40%. При тонкостенности гильзы

требуемое качество тонкостенных гильз, а следовательно, и труб не обеспечивается.The task is achieved due to the fact that to obtain high-quality pipes with thin-walled

thin-walled sleeves required for this with

receive due to two firmware on the helical rolling mill with subsequent deformation of it along the wall on the expander mill by 30-50% with a diameter increase of up to 30-40%. With thin-walled liners

the required quality of thin-walled sleeves, and therefore of pipes, is not ensured.

To explain the invention, an example of the method is described below with reference to the accompanying drawing, which shows a diagram of the pipe production process and the composition of the equipment for its implementation.

The production of large diameter seamless pipes is as follows.

The heated billet is flashed in the mill 1 screw rolling into the sleeve, then the resulting sleeve is flashed on the same mill for the second time, thus, the sleeve is flashed in two passes. After the second firmware, the sleeve is squeezed along the wall and increased in diameter on the expansion mill 2. Next, the rough pipe is run in the screw rolling mill 3 and calibrated on the longitudinal rolling mill 4.

An example of the method.

) нагретую заготовку диаметром 650 мм прошивают в стане винтовой прокатки в гильзу диаметром 700 мм и толщиной стенки 100 мм, потом полученную гильзу прошивают на том же стане во второй раз в гильзу диаметром 880 мм и толщиной стенки 30 мм (тонкостенность

), затем эту гильзу обжимают по стенке на 40% на стане-расширителе при подъеме по диаметру на 39% до указанных выше размеров готовой трубы, обкатывают и калибруют.Upon receipt of pipes with a diameter of mm and a wall thickness of 18 mm 1220 (thin-walled

) a heated billet with a diameter of 650 mm is stitched in a screw mill in a sleeve with a diameter of 700 mm and a wall thickness of 100 mm, then the resulting sleeve is stitched on the same mill for the second time in a sleeve with a diameter of 880 mm and a wall thickness of 30 mm (thin-walled

), then this sleeve is squeezed along the wall by 40% on the expanding mill when it rises in diameter by 39% to the above dimensions of the finished pipe, is rolled in and calibrated.

The proposed method for the production of seamless pipes on aggregates with an expansion mill compared to the known ones allows to obtain high-quality thin-walled pipes of large diameter with a ratio of diameter to wall thickness of up to 70.

Claims (1)

A method for the production of seamless thin-walled pipes of large diameter, including piercing a heated billet into a sleeve in a screw rolling mill, rolling the sleeve on the expander, rolling the draft tube and calibrating it, characterized in that the billet is pierced into a thin-walled sleeve in two passes with a diameter to diameter ratio sleeve wall thickness up to 30.

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