Need a steel engineer

[Wayne County Hose]

I am building a hydraulic nut removal tool for my cylinder shop. I will be removing nuts on the bottom of rods that are torqued to 5,000 ft. lbs and maybe more. I have narrowed the design down to a single piece of steel for the frame, with a piece to hold the rod eye from rotating on one end. On the other end, I am building a hydraulic wrench to turn the nut. I am wondering about what steel to use and what size. Would an I beam be good, or would square tube be better? It would have to withstand 5,000 lbs. of rotational force. Any ideas?

 

[yankeerider]

Do I understand that your hydraulic wrench will have a cylinder at one end and a socket or crowfoot-type device at the other? A picture would help. In general, size is more important than shape.

In bending, the depth of the web is far more important than the thickness, although an I-beam of say, 4" depth may be more flexible than a 4" square tube if the wall thickness of the tube is greater than about 1/2 the thickness of the web.

Normally, shape is dictated by other factors, As for type of steel, if you aren't limited by size or weight, a larger piece of a lower grade of steel will likely be cheaper and easier to weld. If you've got some material you want to use, post the sizes and material and we can help with relative strength.

 

[Wayne County Hose]

Jerry, I would purchase the steel new as this is something with a lot of force and I wouldn't want to risk my body parts with possibly fatigued steel.

The best way I can think of to describe what I want is this would look something loke a log splitter. At one end, I would make a jig to go thru the rod eye, to keep the rod from rotating. On the other side, would be my hydraulic wrench. Basically, a wrench powered by a hydraulic cylinder. i would make different "sockets" to fit different nut sizes.

If you go to this website, Machinery Service & Design, a New Generation of Affordable Hydraulic Rebuilding Equipment, look for the "nut buster." This is my hydraulic wrench that I would build.

If you look at the above website, that is in principle what I am trying to build. I am not looking for the rotational force that they have. That is why I think I can build one out of one piece of I beam or square tube. A pretty large piece, but I would like to keep this as simple as possible. Thanks for any help you can give me, Andy.

 

[Farmerford]

Andy:

In terms of resistance to twisting per pound of weight, round tube is best of all, square tube is little less effective, and I-beam or wide flange sections (H-beam) are much less effective.

Just doing very rough calculations in my head, a square tube of A-36 structural steel (36,000 psi tensile strength) 1/2" thick and 4" on each side should handle about 10,000 ft# of torque without exceeding 50% of its tensile strength.

But if that tube is very long (say 6') it will twist quite a bit with that heavy a load. I am not sure what the twist will do to your machine. Perhaps the holding fixture and the wrench head can swivel on an axis perpendicular to the long axis of the tube to keep the ends reasonably lined up when the tube twists.

The twist is calculable, but I don't know the length of your tube and my references are not at hand.

Perhaps a member with newer information than my four decade old engineering texts can give you a better answer. But if you let me know the length I will give it a try over the weekend.

 

[Renze]

If you're making some sort of clamp, it would probably be best to have it CNC torched out of solid steel. This way you dont have to worry about weld strength or fatigue.

but please sketch it out for us, so we know what you're actually talking about..

 

[Mickey_Fx]

IMO you've not provided anywhere near enough information on the "design" for somone to give you specific information on material and the material's geometry.

If I understand your comments, the single piece of steel you mention in your first post, the frame, this needs to be torsionally strong. "I" beams are not the best chioce for this app. Sq or round would be better. Length of the frame and the amount of acceptable twist needs to be known before a particular kind/size of material could be reccomended. Would also need to know how far away from the frame the center line of the cyl is.

Then I may be all wet with my comment.

EDIT:

Looks like while I was composing, farmerford posted his comments. Looks like we are not far away in our thinking.

 

[Wayne County Hose]

Sorry guys, looks like my ignorance on this subject is coming to the surface. I would draw something, or post a pic, but I don't know how. I've asked a few times, everyone tells me to email it to them and they will post it. That doesn't help me learn to post it myself.

Anyhow, I'm thinking 8' max on the length. Distance from the outside edge would be about 8". I will do some more research and post more info later. Thanks for your help, Andy.

 

[RFB]

Wayne County,

check your private msgs.

 

[Shmudda]

Andy,

If you are building this for a business, and you will have employees operating the unit I would HIGHLY suggest to bite the bullett and purchase one!

With the laws of today around "home made" lifting beams, wrenches, and anything else that can break and cause bodily injury it's not worth risking your business.

On the other hand, just remember this too, the drive shafts on vehicles are hollow, which a hollow shaft can take 75% rotational torque of a solid. I could design something like this for you very easily, but I, just the same as most others want to see what you are actually talking about. Then there's always the fear that someone would get injured with it and then everybody and their brother will be sued.

Sad world we live in to say the least.

Craig

 

[Eagleview]

With the different length rods you will be working with it will have to have adjustable headstocks . The steel profiles your thinking of wont stand torsional loads . The steel you choose will have to stay true lengthways not only to resist the torque initially imposed by the spanner but also so that when the nut lets go it wont throw things at you . I would be more inclined to use a thick walled tube with a wall thickness of around 3/4" and maybe 8"-10" in diametre . It would have holes/slots radially cut along its length to accept the pin to hold the ram eye . It would have a 1" Bisalloy 80 flat plate with the center cut out welded to the end in the shape to suit the eye of the spanner ram or rams (remember that you have to have it go both ways so you can re-tighten it later) and provisions to take a hinged safety cage . The unit would be mounted verticaly to the concrete floor . You would lower the ram bar into it with an endless chain , install the eye pin through the side holes , install the spanner on the nut , close the safety cage and push the lever . The tube would be torsionaly strong and also act as a safety shield . Remember that with 5000# of torque applied the ram bar will twist a little and when the nut lets go it will go off with a bang . You may want to think of using a torque multiplier to make the rams job easier .