| 摘要 |
PURPOSE:To improve the flow rate control for the roll coolant oil, by carrying out the PWM control for controlling the flow rate of the roll coolant oil which is hardly effected by only adjusting the opening of the flow control valve, so as to obtain a pulse flow. CONSTITUTION:When the necessary flow rate of the coolant oil is an intermediate value hardly obtainable by adjusting the opening of the flow control valve of the injection nozzle arranged at an arbitrary point along the roll barrel, the opening adjustment of one of the flow control valves is repeated at a constant period sufficiently shorter than the roll's thermal time constant; hereby, the nozzle output is made to take a pulse wave-form, and the PWM control is carried out so as to equalize the mean value of this pulse wave-form nozzle output to the commanded value. For example, when the first flow control valve 2 delivers much more flow of the coolant oil than the commanded value, the pulse wave-form A possessing the pulse width alpha2 is made depending on the PWM command so as to equalize the mean flow rate as the PWM output to the commanded coolant flow rate alpha. The period T is sufficiently shorter than the roll's thermal time constant, and the coolant flow rate becomes equal to the mean value alpha1 of the pulse wave-form A. Hereby, the distortion of the rolled sheet material is reduced. |
