On Thu, Nov 18, 2010 at 11:15 AM, Jon Elson <el...@pico-systems.com> wrote:
> Viesturs La-cis wrote: > > if that is just a base for machine, I suspect that the machine itself > > also will be very massive and very heavy to provide for rigidity and > > vibration damping in order to achieve the high precision in > > hard-to-machine materials. so the question is - what kind of > > bearings/slides are there to be used and what kind of actuators are to > > be used for such a machine? the same old Hiwin rails, but 3 or 4 > > instead of one and same old ballscrews with some extreme 10" diameter? > > > Some of the very large machines are hydrostatic. They look very much > like conventional > box ways, but have an oil port in the center, and and a hydraulic pump > provides a steady > flow of oil to the bearing pad. There is usually some scheme of bladders > or wipers and a > scavenge pump to return the oil to the lube system. Stuart Stevenson at > MPM has a Gidding and Lewis > horizontal boring mill like that, I think the table is about 50 feet long. > The G&L X axis table is around 10 feet long. The machine is considerably longer to handle the 110 inches of X travel. The ways are hydrostatic. There are bladders, oil pumps and vacuum pumps to make the way system work. The bladders are essentially a flattened copper tube, plugged on one end, plugged and ported on the other end. These bladders sit behind the gib. Hydraulic pressure expands the bladders to push the gib against the way. This being my only machine with hydrostatic ways limits my assessment. I like the concept. It is difficult to eliminate the leaks so I just try to minimize the leaks and capture the oil. With this you don't have to worry about the machine rusting. The coolant reservoir is the entire pit the machine sits in. The oil is very effective in reducing coolant water loss to evaporation. thanks Stuart -- dos centavos ------------------------------------------------------------------------------ Beautiful is writing same markup. Internet Explorer 9 supports standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3. Spend less time writing and rewriting code and more time creating great experiences on the web. Be a part of the beta today http://p.sf.net/sfu/msIE9-sfdev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
