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

Beginning Next SlideBack 1 of 21 End Program

AVADAL AVADALSK-1 Roller Apron Segment Overview


AVADAL AVADALSK-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.



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.



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.



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


AVADAL AVADALSK-1 Manual Valve

A manual 4 way, 3 position, detented valve with limit switch, positions the 4 clamp cylinders.


AVADAL AVADALSK-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.


AVADAL AVADAL

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. 3LIMIT SWITCH

DETENT


AVADAL AVADALSK-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.


AVADAL AVADALSK-1 Segments 2,3,4 SY1 ManifoldSK-1 Manual Valve Limit Switches

Valve Limit Switches


AVADAL AVADALSK-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)


AVADAL AVADALSK-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


AVADAL AVADALSK-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.



PILOT OPERATED CHECK VALVE



Pilot Operated Check Valve on Segment 8, 9, & 10



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.


AVADAL AVADALSK-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.



Thermal Relief Valve on Segment 8, 9, &10



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.



PRESSURE RELIEF VALVE


AVADAL AVADALSK-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.

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

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