Causes and Solutions of Rolling Mill Screw Loosening

Due to the rolling force of the rolling mill, its adjustment of the screw nut up and down will be affected to varying degrees, and one of the possible consequences is the automatic unscrewing of the screw in the rolling mill. Under normal circumstances, the automatic unscrewing of the screw is mainly produced on the blooming mill and the strip roughing rolling mill.

Once the rolling mill screw is loosened, it will affect the roll gap and the accuracy of the rolled product, causing the friction angle to become smaller, which will cause the thread rise angle to be close to or greater than the friction angle, resulting in irregular deformation of the rolled product. The analysis proves that the main reason why the rolling mechanism of the rolling mill does not lock is mainly due to the change in the friction state between the screw and the screw nut. Increasing the frictional resistance torque between the threads and appropriately reducing the thread diameter.

Therefore, during the rolling process of the rolling mill, it is necessary to adjust the roll gap, that is, the so-called strip reduction. It will cause the instantaneous rolling force to change, and the lubrication state will be changed. However, the excessively large diameter causes the size of the rolling mill to be too large, increasing the braking torque and solving the loosening of the screw.

At the same time, it can be said that the head of the screw is made into a spherical surface, the purpose is to make the bearing seat have the self-retaining ability, and the cold drawing machine makes the bronze spherical pad in a well-pressed state. In order to increase the self-locking ability of the rolling mill, the depressed screw heads are usually fabricated to increase frictional torque.

For the slab rolling mill, because the steel ingot is pressed, in order to reduce the frictional torque, the tension so that to adjust the reverse tightness of the positive and negative nuts of the screw. The screw head is generally used with thrust rolling bearings instead of copper pads. In this way, it can help to avoid the loosening of the screw of the rolling mill and ensure the quality of the rolled product.