LINK Systems 5100-8 Tonnage & Analog Signal Monitor - Manual (Page 13)

Doc #: L-802-1110 Page 11 Rev. 02
2.3.4 Reverse Limits
A Reverse Limit should be set more negative than the maximum reverse tonnage developed when
properly producing a particular part and is set for each channel of the tonnage monitor for the peak
tonnage only. Data windows do NOT have reverse limits associated with them. If something in the
process changes during normal operation that causes the tonnage developed to exceed this maximum
reverse limit, a Top Stop is issued. Excessive reverse tonnages are damaging to the machine frame and
reverse tonnage limits are active during the entire working portion of the stroke.
2.3.5 Total Tonnage Limit
There is only one limit that can be applied to the total tonnage. If so configured (see section 4.6 on page
48 for details), the machine rating de-rate table will apply a limit to the total tonnage that varies with the
crank angle (related to height off the bottom of the stroke). The machine rating is specified by the press
manufacturer at a specific height off the bottom of the stroke. Above this height the total tonnage
available is limited by the torque of the crankshaft and clutch and will decrease as the height off the
bottom increases. The machine rating de-rate table tells the tonnage monitor how to limit the total
tonnage. A Cycle Stop will be issued if this limit is exceeded.
2.4 Stops
There are three different kinds of stops that the tonnage monitor can generate. Some conditions always
generate a particular kind of stop, while others are programmable by the user.
2.4.1 Cycle Stop
A “Cycle Stop” sends a signal to the control to immediately stop the press, regardless of where it is in
the cycle. Note that this does NOT mean that the press will actually stop at the point where the stop was
generated, as all presses take some amount of time to drop out the clutch, apply the brake, and come to a
stop. For instance, if an over-tonnage occurs at 175 degrees, the press may end up stopped at 200
degrees. The number of degrees a press requires to actually stop depends (among other things) on the
design of the press and on stroking speed. All other conditions being equal, the faster the press is
stroking, the longer it requires to stop.
2.4.2 Top Stop
A “Top Stop” sends a signal to the control to stop the press at the top of the stroke. Note that all presses
take some amount of time to stop. If the control determines that it can not stop at top in the time left
when it receives the stop command, it will make an additional stroke. Many high speed presses take
more than 1 full stroke to stop regardless of where the stop occurs.
2.4.3 Intelli-Stop
An “Intelli-Stop” sends a signal to the control to “Cycle Stop” if the stop can be accomplished by a
certain “critical angle”, otherwise it will “Top Stop”. This stop type is used to attempt to prevent
sticking the slide on bottom under load. For instance, the critical angle might be set to 170 degrees. If
the control determines that the press can stop before this angle is reached, it will issue a “Cycle Stop” to
attempt to prevent further damage to the machine and/or tooling. If, however, the control determines