LINK Systems OmniLink II Press Automation Control - Manual (Page 57)

August 30, 2002 Manual Version 1.0 4.8
top on the Machine Parameters menu. This setting comes from the factory as 0 0 since it is most likely
that your press will have simple eccentric motion instead of the more complex link drive motion. If
your press slide is directly driven by a crankshaft, an eccentric shaft, or eccentric gear you do not need
to change the 0
0 setting. Go to the setting discussed in the next section of this manual.
If the press has a link drive system you must refer to the manual for the press to find what crank or
eccentric angle represents top of stroke. This angle will normally be somewhere between 315
0 and 335 0
depending on the specific press design. Use the arrow keys to select the Top of Stroke Angle setting, use
the number keys to key in the correct angle, and press the ENT(ER) key when done.
Section 4.2.1.3 Setting Minimum Press Speed and Loss Of Motion Time
The OmniLink II Press Automation Control uses a motion detection system to detect any coupling
failure that results in the encoder (resolver) not being driven by the crankshaft. If the resolver de-
coupling occurred, the system would then be unable to perform its monitoring and control functions that
depend on crankshaft angular position. The motion detector generates an immediate stop signal if it
senses motion below the SPM (strokes per minute) configured in the Minimum Press Speed setting for a
period of time greater than the setting for Loss of Motion Time. The Loss of Motion Time setting is
used to compensate for erratic motion on some geared presses where the gears cog back and forth as the
press strokes, resulting in temporary dips below the Minimum Press Speed SPM setting, i.e., the motion
detector threshold as shown in Figure 4.7.
Figure 4.7 Erratic Crankshaft Motion Typical of Some Geared Presses
The Minimum Press Speed setting is limited to values between 2 and 100 SPM, and a entry of a
number beyond these values is rejected. A value well below the actual minimum press stroking speed
should be entered as this configuration setting, preferably in the range of 25% to 30% of actual
minimum press stroking speed although lower and higher values may also be suitable.
The value to enter for the Loss of Motion Time setting depends on the characteristics of the individual
press. Use the following formula to determine your initial configuration setting in milliseconds for this
parameter.
Loss of Motion Time = 3000 divided by maximum press strokes/min (milliseconds)
Example: A variable speed press provides stroking speeds from 20 SPM to 60 SPM. Since 60 SPM is
the maximum strokes/min, 3000/60 = 50 milliseconds. Enter 50 as the initial Loss of Motion Time
setting.
Periodic Dips below Minimum Press Speed setting
SPM
TIME
Average SPM
Minimum Press Speed SPM