The rolling mill adjusts the screw nut up and down under the action of the rolling force reaction force so that the pressing screw is automatically loosened, and the automatic unscrewing of the pressing screw is mainly generated on the roughing mill and the strip roughing mill (middle plate rolling mill). Therefore, the opening degree of the roll gap is affected and the precision of the rolled piece is affected so that the friction angle is reduced so that the angle of the thread is close to or larger than the angle of friction, and the deformation of the rolled piece is irregular.
The main reason for the self-locking of the pressing mechanism is that the friction state between the screw and the nut is changed. Increasing the frictional resistance between the threads appropriately increases the diameter of the pressing screw. In the strip rolling mill, the roll gap adjustment is carried out during the rolling process, that is, the so-called strip pressing, causing the rolling instantaneous impact force to be too large to change the lubrication state, but the excessive diameter causes the rolling mill to be too large in size and increase the braking torque. , solve the screw back to lose.
The purpose of pressing the screw head is generally spherical so that the bearing seat has the self-position ability, the cold drawing machine and the bronze spherical surface pad are under the pressure receiving state; the initial rolling mill is to increase the self-locking ability of the pressing. The screw head is usually assembled to increase the friction torque; the billet rolling mill is used to reduce the friction torque due to the reduction of the steel ingot, and the tension is used to adjust the reverse tightness of the screw forward and reverse nuts. Push the rolling bearing without a copper pad.