Aren't the timer constants actually 3.0 and 1.4 seconds as opposed to 30 and 14?
Opps! I got my PLC platforms mixed up!
Thinking about your constant displacement hydraulic pump, control situation and your comment below
this machine would pretty much never be used enough to justify a serious chunk of money spent on the controls. I would definitely be better off buying a modern production machine. I was just hoping I coule improve this one a bit for now
I believe the best path for improvement would be to:
1. Leave the Gemini connected, but add a high speed counter card (H2-citro) and parallel the wires. I'm presuming this can be done, I have done this before, but it might depend on the encoder's output power.
2. Add a second motor (1.5 hp) The motor starter would be controlled by the PLC, to drive a 1 gpm pump. A pair of check valves would also have to be added to keep the two pumps from rotating the other backwards or spilling to tank.
3. Use the existing optimate for programing two additional bend angles. Assign each bend angle to two separate push buttons.
The operation would be this:
If the operator wanted to use the Gemini he could by using the original controls, nothing would change.
If the operator wanted to use the optimate, a pair of bend angles would be programmed and each line would be assigned to two separate "Optimate designated bend angle buttons". When the first angle was desired, the operator would press that button and the auto bend cycle would start. When the counter card sensed the bend was near completion, the PLC would start the second motor and pump, and unload the main pump. The smaller pump displacement would "creep" the bend arm to the final angle. At this point the small pump would be turned off, and the retraction part of the cycle would start and the main pump would retract the system. When the
second angle was desired, the operator would press that button and the auto bend cycle would start. When the counter card sensed the bend was near completion, the PLC would start the second motor and pump, and unload the main pump. The smaller pump displacement would "creep" the bend arm to the final angle. At this point the small pump would be turned off, and the retraction part of the cycle would start and the main pump would retract the system.
One drawback is that you would be using the friction and resistance of the tube to do the actual "decell". I'm guessing that if you were bending small tube at high speed, the transition point from high speed to creep would need to be much earlier than when you were doing large tube at the same speed. Another drawback would be if the encoder does not have the power to drive both the Gemini and the H2-citro. If it cannot then the Gemini could not be used.
This scheme would use only two extra inputs and one output. If you desired to change the sequence valves out and add limit switches and solenoid valves you would still have some inputs and outputs available. It would also only add one card to the PLC (only 1 available slot).