Pinch roll unit

In a rolling mill in which hot rolled products are directed along a pass line between pinch rolls, and the pinch rolls are opened and closed by an electrically powered servo motor, a method of controlling the operation of said pinch rolls, said method comprising:

• (1) detecting the arrival and speed of a product at a location along the pass line in advance of said pinch rolls;
• (2) based on the results of step (1), determining whether the product size has changed from a preceding size to a new size;
• (3) based on the results of step (2):
• (a) if the product size has changed:
• (i) setting the current limit to be applied to the servo motor to achieve a predetermined pinch roll pressure on the product;
• (ii) energizing the servo motor to move the pinch rolls slowly from fully open positions to closed positions in contact with the product to effect said predetermined pinch roll pressure;
• (iii) determining and storing an interim setting for the servo motor at which the pinch rolls are moved from, said fully open positions to pre-touch positions spaced a short distance from the product;
• or
• (b) if the product size has not changed:
• (i) energizing the servo motor in accordance with a previously stored interim setting to move the pinch rolls rapidly from said fully open positions to the resulting pre-touch positions;
• (ii) setting the current limit to be applied to the servo motor to achieve a predetermined pinch roll pressure on the product;
• (iii) moving the pinch rolls slowly from the pre-touch positions into contact with the product to effect said predetermined pinch roll pressure on the product;
• (iv) determining and storing an updated interim setting for the servo motor;
• (4) awaiting a pinch roll open command;
• and
• (5) energizing the servo motor to return the pinch rolls to their fully open positions.