machining threads on a hydraulic cylinder

admin

I have to machine threads on the shaft of a hydraulic cylinder. I don't think I can dismantle the cylinder to get the shaft out. Does anyone know If I can get threads machined on it or has anyone done anything like this before? thanks.
Reply:Usually there is a packing nut that seals around the shaft. If you unscrew it the cylinder comes apart. Sometimes the nut is round as opposed to hex shaped, or has a notch in it for a spanner instead of a standard wrench.I've torn down and repaired small cylinders before, and often had to tighten the packing nuts to stop leaks. On bigger cylinders that have had issues, we usually send them out to CAT to have them rebuilt, so I usually don't have to F with them much..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:good luck machining threads on a hardened rod.... maybe you can weld a yoke to it? as far as packing goes I have seen a few style packing nuts, wire groove packing nuts are real fun though I haven't seen one of those in a while
Reply:Originally Posted by eyeball engineergood luck machining threads on a hardened rod.... maybe you can weld a yoke to it? as far as packing goes I have seen a few style packing nuts, wire groove packing nuts are real fun though I haven't seen one of those in a while
Reply:Originally Posted by BoostinjdmWhat makes you think it's hardened?  I've machined several rods and once you get through the chrome it's no problem.  Never cut threads though.I'd second welding the yoke idea just because you can do it without disassembly.
Reply:Worked in a hydraulic cylinder plant for a while. Some rods were induction hardened, had to be cut with ceramic tooling. Most however were cold rolled bar , just chrome plated. First, why you need threads on the cylinder rod?Second, if you chuck the cylinder tube and try to machine the rod that no worky.Third, cylinders are very simple and all basicly the same. More info (or picture about the part in question) someone can walk you through disassemble.Ranger 250 GXTSmith Gas Axe
Reply:Thanks guys! I am thinking that welding threads on it is probably the best way to go. I have to have threads on it because I am running two cylinders and they have to be PERFECTLY aligned or as Mr. Lead man said..... No workey!  It is for a tubing roller I am building and the two are going to push evenly on the two take up bearings in (as in pic) I haven't got the cylinders yet, but hopefully they will come with some sort of a msds and I can figure out what the rod is made out of and what the best procedure would be to weld to it. Thanks again guys! .... kris kroll Attached Images
Reply:Originally Posted by krisk1233. . .I am running two cylinders and they have to be PERFECTLY aligned or as Mr. Lead man said..... No workey!  It is for a tubing roller I am building and the two are going to push evenly on the two take up bearings in (as in pic). . .
Reply:hey denrep I was trying to figure out what I would have to do to run the two cylinders at the same time. Can you explain what a flow divider is and what my best coarse of action would be? I am planning on using a hydraulic hand pump with the two cylinders. thanks.. kris
Reply:In this case a  flow divider would take one stream in, and divide it into two equal flows out.Flow dividers are pretty good, but not 100%. When used with cylinders, the cylinders can creep out of sync. I would think that one cylinder with a mechanical link, or yoke, would be a preferred design over two unequally loaded cylinders.Good Luck
Reply:I concur with the preceeding cautionary comments regarding sync problems.  The flow dividers I have seen were basically two gear pumps on a common shaft but driven by the incoming hydraulic pressure, not by the shaft.  Gear pumps all have some degree of leakage and, for any specific pump, the actual fluid leakage is a function of pressure.differential across the pump.  The volume of fluid leakage is also a function of time so you would have even greater problems with a quasi-static configuration, as with a hand pump, or with a static situation, as in holding a fixed position (unless you promptly closed valves upon reaching the desired position.You state that you need PERFECT synchronization, which you cannot achieve with a common flow divider (although there may well be other types with lower leakage that I am not familiar with).Conceivably you could get near perfect synchronization using two identical pumps with ganged handles and two independent hydraulic systems but you would have to return to "home" position to re-synchronize each time you opened valves to retract the cylinders.Basically, I think it's going to be a hassle to achieve the synchronization you desire using two independent cylinders.  Consider ganged screw drives?awright
Reply:Hmmm. I am kind of at a stand still now and wish I would have designed the force roller in a different manner. From everyones input about the two cylinders, it seems that I am going to have quite a bit of slippage especially because one cylinder is going to do much more work that the other and when this happens, the center roller wont go down completely straight and will roll things crooked... no bueno!!!!I am either thinking of a drastic redesign of the center roller (which I am real hesitant to do) or use one hydraulic cylinder with a substantial bracket connecting the two bearings and see if it works. any other advice is greatly appreciated. thanks... kris kroll
Reply:There may be something I am not seeing here.  But looks to me like you could use a lever/ belcrank on each bearing connectrd together outside the case. Then use 1 cylinder to actuate both levers.IF IT WORKS, DON'T FIX IT2 Lincoln CV-300 / LN-7 GMALinde-VI 253,400 & 450 w/MIG35 feedersCNC Table with Oxweld O/A & Hypertherm 1250G3Lincoln Ranger GXT 250Hobart-MicroWire 300ESAB Heliarc 161ESAB-Mobilemaster 2 CC/CV Feeders& more
Reply:You could use electronic feedback to control the flow to each side, but the cost and complexity of the equipment would exceed the rest of the unit, unless you scrounged the components from an existing machine. Not likely to happen.Suppose you had a pair of  fine thread, large diameter screws running in bronze nuts, belt driven by one chain running around large sprockets, the chain being driven by a hydraulic motor? Good  directional control and full torque at all speeds. Put the chain drive up high, out of the way. Or, maybe underneath if the frame will accommodate the change. Simple, strong.
Reply:Millman I was trying to figure out what you meant with the bellcrank Idea? I would appreciate it if you could explain further. To explain my dilemma further, the dies slide on to the shafts outside the housing (about 2-3 inches) and thats where all the load is applied. The two take-up bearings (which the shaft rides through) are about 6-7 inches apart and basically when I crank down on the tension screw the upward force applied at the die  is transfered and pushes the take-up bearing on the opposite side down. Basically it was a poor design on my part, but I am a college student trying to figure this all out, so now Im looking for a remedy so I don't have to do any major rebuilding. I was thinking that if I could have the same downward force applied to both the bearings, then the only movement would come from the shaft (which I am not worried about) thanks again sorry for the novel of a reply post. kris
Reply:You are going to have to push on the bearing closest to the dies and pull on the other.  As far as the bell crank idea goes....  look at this.http://cgi.ebay.com/50-Iroquois-Pres...item1e59be0d19With this type of deal, you wouldn't need hydraulics.  The leverage gained by the linkage would be enough to make cranking a threaded rod by hand fairly easy.Last edited by Boostinjdm; 01-21-2010 at 01:41 AM.Reason: link didn't work for me...My name's not Jim....
Reply:I am pretty new to this site and don't get online very much with my work and school schedule but I really appreciate all the help and advice from everyone. sometimes the easiest solutions are right in front of you but it takes someone else looking to point them out to ya. thanks again.... kris kroll
Reply:hey Boostinjdm do you think you would mind drawing up a rough sketch of what your talking about? thanks..
Reply:I could, but I won't make any promises on when it'll get done.  Trying to solve my own problem right now...  If I get a chance I'll make ya a sketch.My name's not Jim....
Reply:thanks... no hurry I'm on the right track now.
Reply:Krisk,  The picture of the press is very self explanatory and I doubt boostinjim could draw better than the picture.....Sorry JimSee how the hydraulic cylinder is positioned horizontally and has(2) fixed pivot points on both the cylinder rod AND the moving part that does the bending. This single cylinder being actuated forward (open) in turn drives both fixed pivot simultaneously and because of the design, equal force is applied.Just look at the picture for a little while and it will "click".Granthttp://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything
Reply:Well, jakalope, it's not obvious to me, even after studying the photos.I don't see any hydraulic cylinder at all.  What I think I see is a prototype that used a screw to press down on the flat bar spanning between the two blue bearing blocks, the rounded end of which is peeking through the slot above the bearing in the near blue block.  I'm guessing that krisk1233 expected that the linear guides on the front and rear faces would maintain alignment of the shaft.  Since those linear guides would not be adequate to maintain the shaft in it's desired horizontal alignment with the cantelevered loading of the bending sheave, I think he was initially contemplating replacing the screw with a hydraulic cylinder above each blue bearing block.  I think we collectively may have discouraged that idea.If my interpretation of the photos is correct, I reiterate my (and other's) earlier recommendation of two screw jacks coupled with a chain and sprocket drive.  That appears to be fairly easily implementable into his prototype.Despite the design hiccup, nice workmanship.awright
Reply:Ya gotta follow along Awright! I was referring to the ebay link posted. Here it is if you didn't see it the first time.http://cgi.ebay.com/50-Iroquois-Pres...item1e59be0d19This was the example given in order to alleviate the design flaw.Granthttp://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything
Reply:The problem krisk is having is exactly the reason it took me over a year to decide a design for mine. Mine will be similar to that of the Ercolina and Baileigh design. I have machined the 1" thick front and rear plates but mine will ride on machined ways like a giant "T" slot on the front and rear plates. My shafts are 2" diameter and will be powered by hyrdaulic downfeed.Krisk's design is nice ecpet for the main center die and how it rides. It is an inherent problem with a cantilevered design and the only way to overcome this is to have a VERY sturdy front rear slides and equilateral down pressure.Granthttp://jackalopefab.com/MM210Synchrowave 200DXMiller XMT350 w/60series feederMiller Bobcat 250 with SGA 100 and spoolgunHTP PlasmaFull Machine shop with everything
Reply:AAAhh!awright