I just did the controls for a hydraulic press - a new machine that swages 6 stainless steel anchors about 3/4" diameter at the same time. It has an 8" cylinder on it and they are running about 2800 PSI system pressure. The press is quick as there is a 25 hp motor on it with a 10 gallon accumulator. It uses a self regulating swash plate pump. We just finished it up last week and it is making thousands of parts per day now. This machine has a lot of safety features on it. It has a U shaped lock that engages the ram when it is up so the operator can pull the parts out without fear of having their hands crushed. There is a light curtain and a couple of safety relays that monitor the machine as it runs.
We aren't using a servo valve. Just a big 4 way valve controlled by a small Siemens S7-1200 PLC. There is a pressure sensor on the back of the cylinder and when the cylinder comes down and stalls against the parts, (sensed by the pressure sensor) I start a timer and hold the cylinder down for about 1.5 seconds (so the metal can flow) and then retract the cylinder. You might be able to do the same thing. You could probably use one big valve. But if you want to carefully control tonnage a Servo Grade Proportional valve is the way to go.. You could actually ease the pressure on until you were happy with the bend and then push a switch to reverse the cylinders. Those cylinders are so big that you might be able to use a couple of 4 way hydraulic valves with orifices in the right place to limit flow and the rate of tonnage buildup. Do you want to do air bending? If so perhaps a couple of limit switches would be a better way to reverse the cylinders since the desired tonnage would not really be known. Or you could logically combine tonnage, and ram position? Dave On 9/23/2013 5:06 PM, Stuart Stevenson wrote: > On Sep 23, 2013 3:11 PM, "andy pugh" <[email protected]> wrote: >> On 23 September 2013 20:50, Stuart Stevenson <[email protected]> wrote: >>> 2 cylinders - one on each end >>> 500 ton 20' brake press >>> I need to control each end separately. >> I have a feeling that I have seen the machine? > Your feeling would be correct. > >> The 20 ton testing machine I ran could do 36 inches per second running >> with a Moog valve. Given that you probably don't want that speed, I >> think that they would still be an option. >> >> -- >> atp >> If you can't fix it, you don't own it. >> http://www.ifixit.com/Manifesto >> >> > ------------------------------------------------------------------------------ >> October Webinars: Code for Performance >> Free Intel webinars can help you accelerate application performance. >> Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most > from >> the latest Intel processors and coprocessors. See abstracts and register > >> > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ > October Webinars: Code for Performance > Free Intel webinars can help you accelerate application performance. > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from > the latest Intel processors and coprocessors. See abstracts and register > > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
