Event: Locking Lower Work Roll Cylinders - Retract

See the event “HPU – On” for previous steps in this sequence.

 

Note that this event describes the sequences for Mill Stand F1. The same sequences apply for stand F2 through F6, though the component numbers will change. Refer to the relevant schematic for each stand for the appropriate component number.

 

1)    Pressurized hydraulic fluid flows freely through Check Valve 151.01 to the P-port of Directional Control Valve 300.01.

2)    Directional Control Valve is actuated to the parallel flow pattern and the pressurized hydraulic fluid flows through the valve from P to A. Next the fluid flows freely through the A-port of Check Valve Module 174.01 and then into the rod ends of Locking Lower Work Roll Cylinders 712.01 and 712.02, causing the cylinders to retract.

3)    Exhaust flow from the cap ends of the cylinders flows through the B-port needle valve of the flow control module, as the exhaust flow cannot flow through the B-port check valve of the flow control module. Thus, meter-out speed control of the retraction speed of the cylinders is achieved.

4)    Next, the exhaust fluid flows through the directional control valve flowing from B to T.

5)    Finally, the exhaust fluid flows back to tank through Check Valve 089.01 and Duplex Return Line Filter 045.02.