Event: Upper Pinch Roll Entry Side Cylinder - Extend

For previous sequences in this event see the event “Roll Change HPU – On.”

 

1)    Directional Control Valve 303.15 is de-energized to the parallel flow pattern allowing pressurized hydraulic fluid to flow through the valve passing from P to A delivering pilot pressure to open Pilot Operated Check Valves 162.03, 162.04 and 164.05. Pilot Operated Check Valve 162.03 allows pressurized hydraulic fluid to flow to Proportional Pressure Reducing Valve 278.02. The reduced pressure fluid then flows to Accumulator 236.05 and Proportional Pressure Relief Valve 271.01. The pressure settings of these two pressure control valves are used to control the force developed by Upper Pinch Roll Entry Side Cylinders 654.01 and 654.02 as they extend to lower the Pinch Roll.

2)    With Pilot Operated Check Valves 162.04 and 164.05 piloted open, fluid may freely flow between the pressure control valves, the accumulator and the P-port of Directional Control Valve 310.21. Meanwhile, the pilot pressure port of Pilot Operated Check Valve 162.05 is vented, so that check valve remains closed, blocking pressurized fluid from flowing from the pressure passage in the manifold to the P-port of 310.21. Thus, the pressure of the fluid supplied to 310.21 is controlled by pressure control valves 271.01 and 278.02. Accumulator 236.05 provides compliance to absorb shock caused by variations in the thickness of the strip as the strip acts on the Pinch Roll, and therefore, the pinch roll cylinders.

3)    Directional Control Valve 310.21 is energized to the crossover flow pattern allowing pressurized hydraulic fluid to flow through the valve, passing from P to B, then to Flow Control Valves 182.06 and 182.07. The fluid flows freely through the check valves in the two flow control valves into the cap ends of Upper Pinch Roll Entry Side Cylinders 654.01 and 654.02, causing the cylinders to extend.

4)    Exhaust flow from the rod end of Entry Side Upper Pinch Roll Cylinder 654.01 is forced to flow through the needle valve of Flow Control Valve 182.05 by the check valve in 182.05. Similarly, exhaust flow from Entry Side Upper Pinch Roll Cylinder 654.02 is forced to flow through the needle valve of Flow Control Valve 182.08 by the check valve in 182.08. Thus meter-out flow control of the extension speed of the cylinders is achieved.

5)    Next, the exhaust flow from the cylinders combine and flows back to tank, passing through A-port Pilot Operated Check Valve Module 171, which has been piloted open by pilot pressure from the B-side of the circuit. Finally, the exhaust fluid flows back to tank after flowing through Directional Control Valve 310.21, passing from A to T, then through Check Valve 122.07 and Duplex Return Line Filter 045.01.