The upper and lower ends of the pull rod are operated by T-shaped screws with opposite rotation, the upper end of the pull rod is matched with the worm gear box, and the lower end is matched with the small base. It is connected with the upper and lower bearing blocks to replace the ordinary mill's gate to bear the rolling force, support the weight of the roller and the pressing mechanism, and participate in the pressing drive to realize symmetrical adjustment. Therefore, it is required that the pull rod should have high strength, stiffness and good toughness, be able to withstand alternating load and wear resistance, so the pull rod should adopt S34C r2N i2M O. By adopting this structure, the symmetrical adjustment is realized, and the rolling line is fixed and invariable, so that the adjustment, installation and maintenance of the guide and guard device are very convenient, the operation accident and process accident are reduced, and the yield of finished product and operation rate are increased. Roll balancing device Due to the dead weight of the bearing seat and the upper roll, there is a gap between the pull rod screw and the down nut. If this gap is not eliminated, then the impact will occur in the gap when rolling, affecting the stiffness of the whole frame, so it is necessary to use a balancing device to balance the weight of the upper bearing and the upper roll to eliminate the gap. Compared with ordinary brand mill, the advantages of short stress line mill are that it shortens the stress loop and improves the rigidity of the mill, thus obtaining high precision products. Compact design, small size, light weight, simplify assembly, reduce a lot of basic work; When the roll ring is replaced during rolling, the guide and guard device is kept in its original position and does not need to be updated and moved. The symmetrically adjusted roll gap ensures the fixed rolling line and thus prolongs the life of the guide and guard device. (1) The short stress line mill is equipped with more than two sets of rolls. Roll change is to remove the old roll set and replace the new roll set, which requires a lot of spare parts, including rolls, bearing housing, pull rod, worm gear box, worm, etc., which relatively increases the cost. (2) Due to the heavy force on the pressed nut and inconvenient replacement, in case of damage, the whole set of rolls and worm gear box should be replaced. (3) The short stress line mill parts of the processing precision is high, the required processing equipment precision is high.