Prospects for Use of the Reserve Forces of Friction on Contact Surface in Deformation Zone at Rolling to Increase Process Efficiency

Abstract

Rolling process is carried out due to power supplied to the center of deformation using contact friction forces. Rolling takes place in two stages – the capture stage and the steady-state process. The capture stage determines possibility of deformation in rolls. During this period, retracting forces of friction are used with maximum efficiency. The main stage of rolling is the steady-state stage of the process, where contact friction capabilities are not fully used and reserve of friction forces is created, which can increase efficiency of rolling process. To balance excessive friction forces on contact surface in deformation zone during the steady-state process, zones of advance and adhesion appear. Their length characterize amount of excessive friction forces. Theoretical dependences for determining slip and adhesion zones are given taking into account variety of rolling factors. Estimation indicator of abilities of friction forces reserve at the steady-state stage is offered as well as dependence for its definition. It is analytically established that in steady-state stage of rolling on smooth rolls with ratio α/μз = 1 it is possible to supply 1.7 – 2 times greater energy due to exis ting reserve of friction force than at the stage of capture at a lower ratio α/μз ; these numbers are even higher for rolling on grooved rolls. Dependence which determines amount of additional power provided by friction forces reserve is given. Promising directions of using friction forces reserve at the steady- state stage of rolling are provided to improve its efficiency. On the example of rolling in drive – non-drive stand, an increase in efficiency (Efficiency Ratio) of the main line of rolling mill is established with more efficient use of friction forces at the steady-state stage of rolling process. Theoretical dependences are given to determine Efficiency Ratio at usual rolling process and at more full use of friction forces reserve.