Electrically driven reversing rolling mills

The load conditions under which motors driving continuous running rolling mills operate is generally understood, and the advantage to be obtained by using a suitably designed flywheel is well known. Owing to the rapidly fluctuating load, some system of energy storage capable of performing a large amount of work for short periods must obviously be of considerable value not only from the standpoint of motor operation but also from that of power supply. Several papers have been read before this Institute dealing with the question of the action of flywheels with such loads and the advantage has been clearly demonstrated. The value of flywheels can be best appreciated when used with mills with very high and short peak loads, such as a blooming mill, where loads up to 10,000 h.p. for one or two seconds are not infrequent. The antithesis of this type of mill is the reversing mill where every effort is made to reduce the flywheel effect to a minimum so that the accelerating force required may be kept within reasonable limits. Most engineers connected with industrial work are familiar with the development of electrically driven continuous running mills but the development of the reversing mill is not generally appreciated except by those more or less connected with their design and operation. The object of this paper is to briefly review some of the more important points in its design and operation.