AN EFFICIENT METHOD OF SIZING I-BEAMS AND CHANNELS

摘要

At present, I-beams and channels are rolled in closed beam passes with finish rolling in four-high or in ordinary two-high stands. The wear of beam and channel passes, as a rule, is determined by the condition of the sections forming the places where the walls meet the inside flange laces of the profile being produced. At these places, fine particles of the roll pass's surface flake off. We will consider the process of forming the metal in the strain center of a finishing pass in order to explain the reason for intensive destruction of these sections on the rolling surface of the rolls. The zones of maximum rolling pressure on the roll's rolling sufaces are concentrated in the places where the walls of the feed the flanges, since part of the volume of the wall's metal being displaced under the action of pressure forces of the upper and lower rolls goes to stretching, and part to spreading. However, spreading of the metal of I-beam and channel in the finishing pass is limited by the vertical rolls in a four-high pass or by the outer side walls in a closed pass; therefore, in zones of the walls' transition to the flanges significant internal stresses arise. They far exceed the stresses arising in other elements of the profile. These stresses are transmitted to the rolling suface of the roll and accelerated wear of it. Consequently, by decreasing the rolling pressure on the rolls in the zones under consideration it is possible to decrease the of the rolls. This can be achieved by sizing, if reduction conditions are created that would provide for equivalent rolling pressure in all elements of the roll pass.