LS-CS-M-023
PCSS-F Additions Technical Manual
Page 4-13
Original Language Version:
1.02
Released:
03/12/2013
Standard inputs on the PCSS unit are used for monitoring the normally open (NO) contact left
and right side level limit switches. Either of these switch contacts are normally set to close
when the pressing beam is out of level to the left or the right side but should never occur on
both at the same time. These contacts should be set to close within or before the maximum
limits of the press brake are reached and are usually set to the limit as defined for the CNC
controller. When this limit is reached, any further down movement of the pressing beam is
prevented by the PCSS but can be moved up to re-level the pressing beam again. Details of
these conditions appear in
A safety input of the PCSS unit monitors the overall level limit of the pressing beam by
combining left and right side level limit switch normally closed (NC) contacts in series. These
contacts should be set to open when the absolute maximum parallelism of the press brake is
reached. In this situation, an immediate emergency stop condition occurs, preventing any
further operator control until this condition is reset on the PCSS. Once the condition is reset on
the PCSS, the maximum out of level state still exists. The PCSS allows the operator to restart
the machine; however no down movement can occur. Only then is the operator able to drive
the pressing beam up, thereby re-levelling the press brake and allowing normal operation.
Details of these conditions appear in
Any fault condition of the switch connections for these inputs will also be monitored to ensure
the NO and NC contact inputs are always in the correct state. Any fault in the monitoring of
these switches will cause a condition to be flagged and an emergency stop to occur. It is
therefore important to ensure that each of the level limit switches is operating correctly. Both of
the NO contacts should never be allowed to be on at the same time and the NC contacts
should not open without one of the NO contacts opening first. Details of these conditions
appear in
The level limits can vary between different press brakes and the maximum parallelism that can
be applied depends on their mechanical design. The only method that the PCSS uses to
check that the level limits of the press brake are within the acceptable range (or if any fault
condition exists) is by monitoring level limit switches. It is therefore important to ensure that the
operation of these switches occurs correctly according to the limits specified for the press
brake.
