>>Why would ram position not be sufficient for air bending? I think that would work, but I would probably also want to know cylinder pressure so I could set tonnage limits in an attempt to prevent breakage if something goes wrong.
Decent pressure sensors are 2-$300 each. Cheap insurance compared to everything else. So you really need a servo grade proportional valves and a position feedback device for each cylinder, so you can setup a position loop for each cylinder. I used some big Parker valves a while back that where being fed by a 20 hp pump, with 2000 psi system pressure and I think the valve alone was in the $1600 range. If you can find a couple of 10 gallon accumulators, that would really increase the speed of the machine. Dave On 9/23/2013 6:08 PM, Stuart Stevenson wrote: > air bending mostly > Why would ram position not be sufficient for air bending? > Would tonnage be more important when coining? > I want to control both sides so I have the option of easily bending one end > more than the other. > > > On Mon, Sep 23, 2013 at 4:32 PM, Dave Cole <linuxcncro...@gmail.com> wrote: > >> 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" <bodge...@gmail.com> wrote: >>>> On 23 September 2013 20:50, Stuart Stevenson <stus...@gmail.com> 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. 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See abstracts and register >>> >>> >> http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk >>> _______________________________________________ >>> Emc-users mailing list >>> Emc-users@lists.sourceforge.net >>> 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. 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