The electrical driving of rolling mills

The estimating of the power required to drive rolling mills is largely a matter of experience and the use of tests carried out on mills as similar as possible, but the paper gives a few formulae which have been employed for this purpose. In mills where the load fluctuates considerably, flywheels are desirable and the use of these is discussed, together with the mechanical arrangements of the drives. Several types of variable-speed non-reversing drives are described, together with the limitations of each system. For very wide speed variations and for the larger reversing-mill equipments the use of Ward-Leonard or Ilgner control is essential. A description of a large equipment, together with details of the necessary control gear, is given, arious alternative details being discussed. Various methods of improving the power factor in rolling-mill electric drives are then considered. Owing to the importance of the auxiliaries for rolling mills, a section is devoted to this question, together with descriptions of new devices. The drives referred to in the paper are in general those for mills to roll iron and steel products, but the particulars are applicable in most cases to drives for mills rolling non-ferrous materials.