DISTRIBUTION OF SPECIFIC METAL FORCES ON THE ROLL AT PIPE ROLLING IN THREE-ROLL SCREW-ROLLING MILL

Abstract

The peculiarity of power parameters of screw rolling process of pipes on a three-roll rolling mill is the presence of two areas: reduction and compression with diff erent specifi c forces of metal acting on the roll. The reduction zone is formed by a tangential expiration, as well as plastic bending sleeve wall in the gaps between the rolls and depends on the mill chamber tuning parameters, geometric parameters of the derived pipe, namely, the ratio of the diameter to the wall thickness D / S. Computer modeling of rolling process has shown that a distributed force or stress of the metal on the roll in the reduction zone is 75% of the eff ort in the compression zone with either major deformation of the liner wall. Stress reduction in the deformation depends primarily on the wall thickness of the liner. With the change of the liner wall thickness along the length of the deformation zone specifi c force in the reduction zone is reduced by an average of 20 MPa. In the compression zone, the value of the metal eff orts on the roll depends on the width of the contact surface and the impact of additional compressive and tensile stresses from the reeling mandrel mill. Determination of compression forces in the drafting area makes it possible to calculate the estimated force acting on the mandrel, which is especially important in the calculation of rolling modes on the controlled movable mandrel.