Rockwell Automation 1771-QDC, D17716.5.85(Passport) MNL. PLASTIC MOLDING MODULE - Manual (Page 150)

Tune Your Machine for Producing Parts
Chapter 10
10-4
4. Slowly increase the integral term while running machine cycles until
profile pressure actuals overshoot profile setpoints. Now decrease the
integral term until overshoot disappear.
Important: If you cannot make pressures actuals match entered setpoints,
verify your Unselected Valve Set-output Values are correct for your
application (Refer to chapter 7 and the discussion later in this chapter).
Tune Pressure Loops with an Oscilloscope
Before you begin tuning your pressure loops, confirm that you:
selected the pressure vs. position algorithm
selected closed-loop control
zeroed the integral and derivative terms
did not change the proportional term that you entered in chapter 7
disabled
ERC
reset ERC values
disabled
ramping
downloaded all setpoint changes to the QDC module
1. Connect the oscilloscope to your selected pressure control valve.
2. Enter the desired operational profile for a production cycle.
3. Run several profile cycles while observing the oscilloscope trace.
Ideally for each step of a multi-step profile, the oscilloscope trace
should rise or fall quickly and then flatten without bouncing.
If: Then:
Your scope trace for any given profile step
never levels off (it is either rising or falling for
the entire step)
Increase the proportional term
Your scope trace for any given profile step
rises (or falls) quickly and then bounces" or
chatters" around a voltage/current
Decrease the proportional term
Excessive hammering and vibration is
observed in the cylinder's hydraulic lines
Decrease the proportional term
Important: Each time you change a gain constant, you must download the
change to the QDC module. Refer to the download procedure in chapter 4.
4. Re-run the profile after each change to the proportional term until
oscilloscope traces quickly level off without bounce or chatter.
5. Slowly increase the integral term while running machine cycles until
you observe overshoots on the oscilloscope trace. Now decrease the
integral term until overshoots disappear.