1. BeginningNext SlideBack End Program AVADAL 1 of 21 SK-1 Roller Apron Segment Overview

2. BeginningNext SlideBack End Program AVADAL 2 of 21 SK-1 Overview The function of SK-1 circuit is to open and close the top roll frame and provide elasticity in segments to prevent damage from the dummy bar. The top roll frame is temporarily opened while replacing mechanical stops for different strand thickness. Upon changing stops, the top roll frame is closed down against the stops for casting position.

3. BeginningNext SlideBack End Program AVADAL 3 of 21 SK-1 Overview A segment consists of two frames, each with a set of rolls. The bottom frame is pinned to machine members and top frame is secured to bottom frame by guides and four double acting cylinders. The cylinders are mechanically and hydraulically tied together and work in unison to open and close the segments.

4. BeginningNext SlideBack End Program AVADAL 4 of 21 SK-1 Overview The cylinders when retracted close the top roll frame down on stops on bottom roll frame, producing the proper gap between rolls for casting position. Pressure is maintained on cylinders to hold this position during casting process. There are nine roller apron segment circuits on each strand corresponding to segments II through X. Segment 1 is no longer hydraulic.

5. BeginningNext SlideBack End Program AVADAL 5 of 21 SK-1 Overview Each circuit consists of a directional valve, flow control valves, pilot check valves, flow meter, and thermal relief valves. Valve Station for Segments 8,9,10 Shown

6. BeginningNext SlideBack End Program AVADAL 6 of 21 SK-1 Manual Valve A manual 4 way, 3 position, detented valve with limit switch, positions the 4 clamp cylinders.

7. BeginningNext SlideBack End Program AVADAL 7 of 21 SK-1 Manual Valve These positions are selected by manual operation of the handle and are held in position by the detent feature. Position #1 is also maintained with safety pin as this position must be held during all casting operations. An attached limit switch monitors position #1 at all times and feeds signal into electrical controls.

8. BeginningNext SlideBack End Program AVADAL 8 of 21 When the valve is in #1 position, pressure is directed to the rod end of the cylinder while the cap end of cylinder is connected to tank. This causes the cylinder to retract. #3 Position directs pressure to the cap end while rod end oil is returned to tank causing the cylinder to extend. #2 Position is neutral, all ports blocked. SK-1 Manual Valve POS. 1 POS. 2 POS. 3 LIMIT SWITCH DETENT

9. BeginningNext SlideBack End Program AVADAL 9 of 21 SK-1 Manual Valve Limit Switches The limit switches are incorporated to transmit electrical signals as to the valve's position. The switch is spring returned to neutral in valve position #1, which is monitored and activated in the other positions. All nine limit switches are series wired so that all valves must be in position #1 before an okay to cast is indicated on the operator's station.

10. BeginningNext SlideBack End Program AVADAL 10 of 21 SK-1 Segments 2,3,4 SY1 ManifoldSK-1 Manual Valve Limit Switches Valve Limit Switches

11. BeginningNext SlideBack End Program AVADAL 11 of 21 SK-1 Manual Valve Limit Switches The valve must be in position #1 before permissive is given for high pressure valve in SK-2 module to open. If any of the nine valves are moved to positions #2 or #3, the switch signals LP pump to start, and run, until all valves are restored to position #1. HIGH PRESSURE VALVE (Shown in Permissive State)

12. BeginningNext SlideBack End Program AVADAL 12 of 21 SK-1 Flow Controls Variable flow control valves are incorporated into the circuit to control cylinder travel speed. All flow controls must be adjusted to synchronize the 4 cylinders on each segment. If cylinders are not synchronized binding can occur with possible damage. Manifold mounted Flow Control on Segment 4

13. BeginningNext SlideBack End Program AVADAL 13 of 21 SK-1 Pilot Operated Check Valve The pilot operated check valve is necessary to prevent cylinder extension during the casting operation even if hydraulic pressure fails. The valve is piloted off pressure that feeds the cap end of the cylinder, which is only pressurized when the directional valve is in #3 position. This extends the cylinder, allowing flow from the cylinder rod end to vent through the check valve.

14. BeginningNext SlideBack End Program AVADAL 14 of 21 SK-1 Pilot Operated Check Valve PILOT OPERATED CHECK VALVE

15. BeginningNext SlideBack End Program AVADAL 15 of 21 SK-1 Pilot Operated Check Valve Pilot Operated Check Valve on Segment 8, 9, & 10

16. BeginningNext SlideBack End Program AVADAL 16 of 21 SK-1 Pilot Operated Check Valve The valve allows free flow to the cylinder at all times. If it is necessary to replace these valves particular attention should be taken that correct flow direction is maintained.

17. BeginningNext SlideBack End Program AVADAL 17 of 21 SK-1 Thermal Relief The thermal relief valve is provided to protect against thermal expansion of the cylinder fluid due to the rapid changes in temperature within the cooling chamber where this equipment is located. The approximate ambient temperature change is 180°F from dry to wet conditions.

18. BeginningNext SlideBack End Program AVADAL 18 of 21 SK-1 Thermal Relief Thermal Relief Valve on Segment 8, 9, &10

19. BeginningNext SlideBack End Program AVADAL 19 of 21 SK-1 Thermal Relief Since the fluid in the rod end of the cylinder is confined because of the pilot operated check valves, the pressure will rise as the temperature rises. If the pressure raises to the setting of the relief, about 3,300 PSI, the spring loaded poppet is overcome, venting excess pressures to the drain line. The poppet closes when the excess pressure subsides below 3,300 PSI.

20. BeginningNext SlideBack End Program AVADAL 20 of 21 SK-1 Pilot Operated Check Valve PRESSURE RELIEF VALVE

21. BeginningNext SlideBack End Program AVADAL 21 of 21 SK-1 Flow Meter The Flow Meter on SK-1 is used to indicate a cylinder or valve by-pass condition. When the cylinder is in a retracted position (rod end pressurized), the flow through the meter should be negligible.