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Ingot rolling system

  1. Sep 13, 2017 #1
    Could you please help me to understand how this steel ingot rolling system works.
    The simplified diagram of a rolling mill is shown in the figure attached. The upper roller of mass m is driven by an electro-hydraulic actuator his objectif is to adjust the thickness to be given to the ingot moving to the right. The inferior roller is driven by a synchronous motor via a flywheel, his role is to compensate the sudden forces which act on the roll without increasing the power of the engine. The thickness y (t) of the laminated ingot is measured using a contact sensor of factor K2. The desired thickness is set using a potentiometer of factor k1. The normal force, FN, acting on the upper roller is considered disturbance.
    Capture d’écran 2017-09-13 à 11.08.05.png

    My questions:

    1. how can the inferior roll compensate the sudden forces which act on the superior roll without increasing the power of the synchronous motor?

    2. What can be sudden forces (example) ?

    I’ve tried to model this "steel ingot rolling automatic control system" graphically.
    Capture d’écran 2017-09-13 à 15.53.36.png

    It is correct ? Should i add the command of the inferior roller in my graphical model? i just want to understand the feedback system control

    Please this is not homework. thank you in advance
  2. jcsd
  3. Sep 13, 2017 #2
    It is the lower roller that drives the ingot to the right. As the position of the upper roller changes, you could have sudden demands for additional torque from the lower roller. Ultimately, that has to come from the motor. But by using a flywheel, that additional power can be added over a longer period of time - perhaps seconds instead of milliseconds.

    Your graph looks OK to me.
  4. Sep 13, 2017 #3
    hello .Scott , thank you for you reply. I don't understand very well. More torque means more power in the input of motor ? if i suppose that instead of flywheel i have speed variator and i want to control sudden forces. can i model the system like that ?
    Capture d’écran 2017-09-13 à 17.17.44.png
  5. Sep 13, 2017 #4
    There will still be speed variation, but with the flywheel, at least the ingot will continue to move. Otherwise, it is possible that the system would simply brake to stop. Alternatively, a larger motor could still deliver the sudden burst of torque, but could pop a circuit breaker in the process.
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