Rockwell Automation 1771-QDC, D17716.5.85(Passport) MNL. PLASTIC MOLDING MODULE - Manual (Page 151)

Tune Your Machine for Producing Parts
Chapter 10
10-5
Important: If you cannot alter your proportional and integral terms so
oscilloscope traces quickly level without bouncing, verify your Unselected
Valve Set-output Values are correct. Refer to this topic later in this chapter
or in chapter 7.
General Guidelines for Velocity Tuning
If your machine will never run velocity profiles, skip this section.
In this section we present two procedures:
Tune Velocity Loops without an Oscilloscope
Tune Velocity Loops with an Oscilloscope
Use either one of these procedures for tuning closed-loop control of the
injection velocity vs. position profile. Tuning constants are the same for
velocity and pressure-limited velocity profiles.
Follow these general guidelines when tuning a closed-loop velocity profile:
Disable ramping
Disable Expert Response Compensation (ERC)
Set IPC04-B11 = B10 = B09 = B08 = 1
Reset ERC values to zero. Set DYC05-B15 (B34/463) = 1.
The QDC module resets this bit to zero after resetting ERC values.
Important: Tuning constants differ between velocity profiles. The
dynamics of loads being moved and different hydraulic characteristics
warrant separate tuning considerations for each profile.
Use proportional control with a zero feedforward term.
(Add feedforward only if required.)
Important: In most cases, adding a feedforward term to the VelFF
algorithm makes it too sensitive and does not enhance loop stability.
Important: Never use feedforward gain and ERC in the same velocity
profile.
Use the highest possible P gain constant for repeatable performance
without hammering your hydraulics.
Use an oscilloscope, if available. You can tune loops faster and easier
with it connected to QDC module’s output driving the selected valve.
Important: If you have an oscilloscope, skip to the section Tune Velocity
Loops with an Oscilloscope.
Tune ClosedĆloop
Velocity Control