Усовершенствование технологии деформирования в рельефных валках путем реализации асимметричной прокатки

Among many methods of improving metal products quality, metal forming methods, applying intensive plastic deformation, take a special place. Results of a study on perfection technology of plate workpieces deforming in relief rolls presented. Application of the technology ensures receiving by a workpiece additional level of shear deformation in transverse direction due to special design features of roll profile. Besides due to various rolls rotation speeds, state of kinematic asymmetry arises, which results in additional level of shear deformation in longitudinal direction. It was revealed by Deform program simulation of metal deformed state that the workpiece is not bent practically after getting out of the relief rolls, keeping its horizontal path of motion. It was shown that the effect is reached due to relief section of the workpiece, where micro-ridges and micro-cavities are formed acting as reinforcing ribs. At that the level of deformation increases by nearly 20% comparing with symmetric rolling in relief rolls. Analysis of state of stress by calculation of Lode‒Nadai coefficient showed that in the central zone of the workpiece mainly compressing stresses are formed, reaching maximum values in the area of comb; at the inclined sections due to action of shear deformations the level of compression is decreased. The surface zones have similar stress distribution comparing with the central one ‒ in the areas of combs compressive stresses are formed, which are considerably lower comparing with those of central zone. On the inclined sections the value of Lode‒Nadai coefficient tends to zero, which gives evidence of intensification of shear deformation in these areas. Analysis of workpiece deformation after rolling in the relief rolls and having next two passes in smooth rolls showed that the proposed variant of rolling technology enables to obtain at the exit a smooth workpiece with insignificant wedging out. Since initially the technology was elaborated for multi-stand mills, these wedging outs will be completely deleted during further passes where the workpiece will have definite reduction by thickness.