Device for controlling the lifting and pressure movements of strip pressure rolls for hot rolled strip coilers

An apparatus for controlling the winding of metal strip on a mandrel having at least one pressure roll provided with a hydraulically controlled cylinder unit and adapted to press successive windings against said mandrel and to be lifted upon the approach of a leading edge of the strip to said pressure roll, said apparatus comprising:

• a control valve connected to said hydraulically controlled cylinder unit for regulating pressure generated thereby of said pressure roll against said windings and for controlling the position of said pressure roll;
• a pressure sensor responsive to hydraulic pressure at said cylinder unit for generating an actual value pressure signal and a first comparator receiving said actual value pressure signal and a setpoint pressure value for producing an output by comparison of said signal and said value;
• a pressure controller connected to said first comparator and receiving said output and being connected with said valve for controlling same to establish the actual pressure in said unit in correspondence with the setpoint value supplied to said first comparator;
• a position sensor responsive to the position of said pressure roll for generating an actual value position signal;
• a second comparaor receiving said actual value position signal and having a output resulting from a comparison with said actual value position signal;
• a position controller connected to said second comparator and receiving the output of said second comparator for generating said setpoint value, said position controller being connected to said first comparator for applying said setpoint value thereto;
• and
• means connected to said second comparator for applying thereto selectively in accordance with the position of said leading edge relative to said pressure roll two setpoint levels for respective comparison with said actual value position signal and respectively corresponding to a lifting of said pressure roll away from said coil and to the application of coiling pressure by said roll to said coil in accordance with the position of said edge relative to said roll to prevent damage to the strip by application of roll pressure in a region of said edge, whereby said setpoint value is varied in correspondence with the setpoint level applied to said second comparator.