LINK Systems OmniLink II Press Automation Control - Manual (Page 87)

August 30, 2002 Manual Version 1.0 5.4
WARNING! When your press is equipped with two-hand control devices and/or presence
sensing devices for point of operation protection, only qualified personnel with a knowledge of the
latest ANSI (B11.1), OSHA (CFR 1910.217), and other regulations that govern the relationship
between stopping time and the distance at which two-hand control and/or presence sensing devices
are to be located should set or reset Stop Limits for the brake monitor. These limits must never be
set for longer times than the time on which the safety distance is based.
Section 5.2.2 Clutch Engagement Time Monitor
The clutch engagement time is measured each time the clutch/brake valve is engaged as the time from
valve activation until crankshaft rotation exceeds the "minimum strokes/min" threshold. If the actual
time exceeds a maximum limit, the stroke is aborted and the Reason for the Last Stop diagnostic
message will be “Motion Did Not Start”. Both the minimum speed threshold and the maximum
engagement time can be set only in the configuration menu (See Section 5.2.4 and Section 5.2.7). If this
message appears, you can reset the fault and try to stroke the press again, but generally the same fault
will occur again.
The Clutch Engagement Time Limit is used two ways by the system. First, the Motion Detector which
makes sure the resolver is turning when the press is stroking will not stop stroking at the beginning of a
stroke as long as motion starts within the time limit set for clutch engagement. Secondly, the Clutch
Engagement Time limit provides useful diagnostic information relating to clutch wear. As clutch plates
wear, increasing the volume of air that must flow into and be stored in the clutch air operator, clutch
engagement time gradually increases. The increased volume of air stored in the clutch also takes longer
to flow out when the air valve dumps pressure to stop stroking, resulting in longer stopping time for the
press and perhaps tripping out the brake monitor. Most (though not all) presses provide for adjustment
or shimming to compensate for clutch wear. In some, you must replace the friction plates when worn by
a certain amount. Exceeding the clutch engagement time limit tells you that clutch adjustment or
shimming should be performed. When possible, it is preferable to adjust the clutch clearance to the press
manufacturers recommended setting to determine the clutch engagement time with optimum clearance.
Section 5.2.3 Critical Angle and Intellistop
The critical angle setting on the Brake Monitor and Diagnostic screen is used, in conjunction with
Link’s Intellistop stop function, to decide whether to apply an Cycle Stop (immediate stop) or a Top
Stop to press stroking. When sensors associated with Die Protection, Analog Process Monitor, or
PLS/Logic inputs detect a fault, each channel monitoring a sensor has a choice of Cycle Stop, Top Stop
or Intellistop settings that the user may program for each job. Generally, when a sensor detects a fault,
the ideal situation is to either Top Stop or Cycle Stop the press before the dies close again to prevent
possible damage to the die or press. But whether this can be done depends on where in the press cycle
the fault is detected and how many crankshaft degrees are traveled after the stop signal is applied. If
press stroking cannot stop when a sensor detects a fault before the dies close, it is then usually best to
apply a Top Stop to prevent the possibility of sticking the press on bottom (dies closed).
When the Intellistop setting is chosen for a sensor channel, the OmniLink II Press Automation Control
automatically makes the decision to Cycle Stop or Top Stop stroking. It makes this decision based
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