Rockwell Automation 1771-QDC, D17716.5.87(Passport) CLAMP AND EJECT MODE - Manual (Page 171)

Span Your Clamp and Ejector Valves
Chapter 9
9-35
If current settings do not match our recommended values from previous
chapters, we suggest you correct these values now using the download
procedure discussed in chapter 4.
Span Your Ejector Velocity Valve(s)
1. Obtain a copy of the flow rate curves provided by your flow valve
manufacturer. The flow rate curves graphically illustrate the flow
through a valve at different voltage or input current levels and at
different pressure drops across the valve’s spool.
2. From the above curves, determine the minimum and maximum
ejector advance and ejector retract flows available from your flow
valve at the pressure you would normally run during ejector
operation. Record these flows, along with the input voltages/current
associated with them.
3. Convert the min and max flows obtained from your flow curve to
clamp cylinder velocities. This is done by:
Clamp Cylinder Velocity (in/sec) =
Flow (in 3 /sec)
Area (in 2 )
- where area is the inside diameter of the cylinder. This area may
be different for the rod and piston ends of the cylinder:
Area for Rod End =
I.D. of cylinder
2
Rod diameter
2
π π −
2 2
Area (no Rod) =
I.D. of cylinder
2
π
2
- The flow assumes no restrictions on the exhaust port of the
cylinder.
4. Enter the minimum velocities (usually 0) from the above calculation
into EAC45 and ERC45. Enter the maximum velocities into EAC46
and ERC46.
5. Divide the voltage/current corresponding to minimum velocities by
the full range of the ejector valve(s) input level to determine the
percent signal outputs for minimum. Enter these values into EAC47
and ERC47.
6. Divide the voltage/current corresponding to maximum velocities by
the full range of the ejector valve(s) input level to determine the
percent signal outputs for maximum. Enter these values into EAC48
and ERC48.
7. Download changes to the QDC module (refer to chapter 4 for detailed
instructions).