Mill Controllers

Electric power is largely supplanting all other types of power for steel mill work, probably on account of its superior controllability. In almost any type of mill control the object is to start, stop and reverse the machine and its load in the shortest space of time, work done at constant speed being of minor importance. This leads to an investigation of the acceleration of motor-driven machines. The ratio of gearing between the motor and the machine is one of the important factors influencing the time of starting and stopping the machines. Analysis is made of the effect of gear ratio between motor and machine, and equations are deduced from which can be calculated the best ratio of gearing for quick starting, quick stopping, or quick starting and stopping. While these equations may be used to determine theoretical limitations of speed and acceleration, any deductions drawn from their use must necessarily be modified by practical considerations.