Rockwell Automation 1771-QDC, D17716.5.87(Passport) CLAMP AND EJECT MODE - Manual (Page 183)

Tune Your Machine
Chapter 10
10-10
Tune velocity loops with an oscilloscope
Before you begin tuning your velocity loops, confirm the following:
Velocity vs. position is selected
Closed-loop is selected
ERC is disabled
ERC values have been reset
Ramping is disabled
All setpoint changes have been download to the QDC module
ATTENTION: Prior to running clamp profiles, refer to chapter
8 to verify that the appropriate Low Pressure Close Zone
Overrun or Open Slow Zone Overrun setpoints and bit
selections are entered properly and downloaded to the QDC
module. Do this to minimize the possibility of mold or machine
damage.
Enter an operational profile representative of the movement characteristics
you desire for your production cycle. Zero the appropriate velocity
feedforward term(s) associated with the profile(s), leaving the proportional
term(s) at the default settings you entered in chapter 7.
Run several cycles of the profile(s) while observing the oscilloscope trace.
Ideally, for each step of a multi-stepped profile, the oscilloscope trace rises
(or falls) quickly to a controlled level and then “flattens out”. “Bounce” or
“chatter” when rising (or falling) is undesirable.
If: Then:
Your scope trace for any given profile step
never levels off (it is either rising or falling for
the entire step)
Increase proportional term(s)
Your scope trace for any given profile step
rises (or falls) quickly and then bounces" or
chatters" around a voltage/current
Decrease proportional term(s)
Excessive hammering and vibration is
observed in the cylinder's hydraulic lines
Decrease proportional term(s)
Important: Each change to a tuning constant requires you to download
your changes to the QDC module. Refer to the Download Procedure
outlined in chapter 4.
Repeat the profile(s) cycles after each change to the proportional term(s)
until observed oscilloscope traces quickly level off without any bouncing
or chattering.