Kevin1793
Member
Hi everyone. I'm working on the design of a semi-automated pneumatic vertical press controlled by a non-safety PLC . It’ll consist of two double-acting cylinders with 5/3 closed center valves and pilot-operated check valves on cylinders ports to keep them in position. An e-stop, light curtains, a dual monitored dump valve, safety relays and force-guided relays will be the safety devices.
The logic I want for the safety circuit is: If the e-stop is pressed or light curtains are blocked while cylinders are moving, the plc outputs power will be cut off and air will be exhausted. Since interrupting curtains during machine cycle a couple of times to load parts will be part of the process, blocking them while the machine is homed will be allowed. In this case air will not be dumped and outputs will keep energized. To achieve this, I want to use safety limit switches to "bypass" the light curtains when they detect the machine is in a safe position.
Can anyone check my safety circuit and give me some feedback of whether my approach and my design are safe or not. Any help will be appreciated. Thank you very much.
The logic I want for the safety circuit is: If the e-stop is pressed or light curtains are blocked while cylinders are moving, the plc outputs power will be cut off and air will be exhausted. Since interrupting curtains during machine cycle a couple of times to load parts will be part of the process, blocking them while the machine is homed will be allowed. In this case air will not be dumped and outputs will keep energized. To achieve this, I want to use safety limit switches to "bypass" the light curtains when they detect the machine is in a safe position.
Can anyone check my safety circuit and give me some feedback of whether my approach and my design are safe or not. Any help will be appreciated. Thank you very much.
