EZTM experience in designing and manufacturing of rolling mill main drive gearboxes

The experience of the Electrostal Heavy Machinery Plant (EZTM) in designing and production of special gearboxes and gear stands for main drive of various rolling mills is summed up. The specifics of section and ball-rolling mills, piercing and reduction mills, mills for cold rolling of tubes and mills for the production of reinforcing bars are considered. It was shown that at designing of special gearboxes for the main drives of rolling mills, the designer, taking into account the parameters of the mill, must build a cyclogram of their loading, which depends both on the range of rolled products and on the variability of loads within the rolling cycle of one billet. In the Designing Department of EZTM, the strength calculation of gears of different types is carried out in the REDUK 4.3 software package, which allows performing strength calculations of gears taking into account the expected loading cyclogram. At the same time, the program provides the initial data for calculating the shafts and bearings, i.e, the forces in engagement and the rotational speed of each of the shafts for the first stage of the cyclogram. The geometrical parameters of the gears are optimized according to the criterion of contact and flexural strength, both between the stages and within each of them.The load sequence diagram depends both on the range of rolled products, and variable loadings in a rolling cycle of a workpiece. Geometric parameters of gears are optimized by contact and bending equal strength, as between the stages as within each of them. Carburizing, hardening and grinding of teeth are provided and secured technologically. Currently, the gearboxes manufactured by the plant are successfully operated at many metallurgical enterprises, both in Russia and abroad. Among them, the gearboxes of main drive of the piercing mill of the Seversk Pipe Plant, the mills for cold rolling of tubes in the USA and China, the section mills at the Yartsevo Casting and Rolling Plant, the reduction mill at the Dnepropetrovsk Metallurgical Plant, etc.