I have a old Baileigh hydraulic press brake that the controller no longer works on. I'm wanting to make a very simple X/Y controller. The X axis is the back gauge which currently is a servo motor and timing pulleys & bets. All that still functions, so I should be able to just connect the controller to the servo driver. The Y axis is the ram of the brake. I want to simply be able to home the ram then input a depth dimension, press the pedal to lower the ram for a bend. Then when the ram gets to that dimension it will stop hydraulic motion. There is a hydraulic solenoid already on the brake, so I assume this is simply having the controller send signals to the valve? I'm not sure how the controller would monitor the linear moment of the ram?
Given the incompressibility of fluids, I'd imagine that hydraulic motion control systems use some form of flow measurement or pre-calibrated pressure/flow curve to calculate position. I wouldn't do it this way for a DIY, though; I'd get a pair of seriously beefy fine-pitch leadscrews (2" x 8tpi or so; I'm sure there are screw thread size load calculators out there to avoid stripping) and use them ganged on each side as a motion-limiter, and allow the ram to operate at constant pressure as a simple on/off/reverse output. Essentially the same result, but almost certainly easier to pull off with existing off-the-shelf parts. Someone with more experience in hydraulics may have a different answer, though.
I think the actual hydraulics would not be part of the controller. I was thinking something like a linear encoder would track the location of the ram. There is already a hydraulic control solenoid on the brake. I just some way to send the solenoid open/slow/close signals.
That's an easy solution to the primary problem, but then you have to give up on Encoder feedback is not a feature of very simple motion control firmwares. Hence my workaround. It's easy to calibrate a screw.
