Abstract
A promising direction for production of simple profiles by rolling includes grooveless rolling. Due to the use of forming in smooth rolls, this direction significantly reduces the production cost of finished products and simplifies the rolling process. However, despite all the obvious advantages of deformation in smooth rolls, there are disadvantages that complicate industrial implementation including the need for edging after each pass and a small coefficient of extraction in smooth rolls. It causes an increase in the number of passes. For the solution of problems encountered in current industrial implementation of grooveless rolling, it is proposed to use deprived-wide vertical stands in continuous groups. Deformation in non-water vertical stands is provided by more complete use of the reserve of contact friction forces of the drive stands installed in front of them. The conditions under which the use of non-water vertical stands is possible are determined. After solving the equation of forces equilibrium on the contact surface in the deformation center of the drive stand, dependence is obtained by which it is possible to find the value of longitudinal force provided by reserve of friction forces. By solving the equation of power balance in form of non-drive rolls, the dependence is obtained determining the longitudinal force required for deformation. The authors offer the dependence by which it is possible to determine the maximum allowed distance between the drive and non-drive stands, providing longitudinal stability of the strip. Using dependencies to determine conditions of deformation in horizontal drive and non-driven vertical mills with smooth rolls, reduction modes during rolling of rebar No. 12 in conditions of JSC “EVRAZ ZSMK” 250 continuous light section mill using roughing stands for grooveless rolling were calculated. As a result it was found that the use of non-water vertical stands allows rolling of larger cast billet of 125x125 mm square on the mill. Economic component of transition to the larger cast billet with development of grooveless rolling was estimated. Advantages of the proposed solutions are shown in comparison with classical method of rebar No. 12 rolling on 250 continuous small-grade mill of JSC “EVRAZ ZSMK”.
Highlights
К недостаткам относятся необходимость кантовок после каждого прохода, снижение общего коэффициента вытяжки ввиду особенностей прокатки с использованием гладких валков, что в свою очередь вызывает необходимость увеличения количества прокатных клетей [4 – 7]
Despite all the obvious advantages of deformation in smooth rolls, there are disadvantages that complicate industrial implementation including the need for edging after each pass and a small coefficient of extraction in smooth rolls
For the solution of problems encountered in current industrial implementation of grooveless rolling, it is proposed to use deprived-wide vertical stands in continuous groups
Summary
Деформирование в неприводных вертикальных клетях обеспечивается более полным использованием резерва контактных сил трения приводных клетей, установленных перед ними. Применив зависимости для определения условий деформирования в приводных горизонтальных и неприводных вертикальных клетях с гладкими валками, были рассчитаны режимы обжатий при прокатке арматуры No 12 в условиях непрерывного мелкосортного стана 250 АО «ЕВРАЗ ЗСМК» с использованием в черновых клетях бескалибровой прокатки. Несмотря на все очевидные плюсы предварительного формоизменения заготовки в гладких валках, имеются и недостатки, серьезно осложняющие практическую реализацию процесса. К недостаткам относятся необходимость кантовок после каждого прохода, снижение общего коэффициента вытяжки ввиду особенностей прокатки с использованием гладких валков, что в свою очередь вызывает необходимость увеличения количества прокатных клетей [4 – 7]. Применение дополнительных вертикальных неприводных валков, установленных в непосредственной близости от приводных и работаю щих благодаря использованию резерва сил трения, поз волит повысить устойчивость полосы, увеличить суммарный коэффициент вытяжки
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