Alternate hydraulic ram push plate & tube; design & calcs

[k75ks]

Enclosed alternative looks like a better method. The tube base in both cases is the 6 X 8 X 3/8. Current design steps it in to the 5 X 5 X 3/16 about mid stroke. Using same tube as full length greatly simplifies fabrication of final ass'y, but I'm not an ME. I worked backwards on the calculations, but only as I understand them, to get the 6" width.

If I'm wrong, kindly point me in the proper direction, I'm not asking for anyone to solve it for me. Thanks for a considered review.

 

[desertfox]

Hi k75ks

Please provide a pdf format

 

[k75ks]

Ok, I'll keep that in mind. Here's the .pdf and corrected ram diameter. I thought we were changing cylinders.

 

[k75ks]

Forgot to explain: step is current design, single is proposed. Sorry, I don't see how to edit my own post. TNX

 

[desertfox]

Hi k75ks

I'm not sure I understand your sketch, I don't see how you can have a cylinder end plate smaller than the cylinder and the cylinder is a rectangular shape.
Is this a continuation of some other thread if so reference it please and provide a better explanation of what your trying to do.

 

[k75ks]

The rectangular tube is what the load is attached to.
The plate is what the cylinder shaft (ram) pushes against.
It's inset in the tube & welded on 2 sides.
The dashed circle is the cylinder shafts' end (centered in plate).

I'm looking for verification of my numbers that the plate won't deform under a repeated #24k load (ergo the 3X safety factor).
I probably should add that speed is ~ 1"/second.

Sorry about being so vague, I'm Real Green at mech diagrams.
Thanks for the help.

 

[desertfox]

Hi k75ks

If the cylinder ram pushes on the plate in the centre of the tube then you don't have any bending in the tube because the ram is acting hrough the tubes neutral axis,if the rectangular tube is a long length compared with its section it might buckle in which case you need to stress it as a strut.
Can you provide a more detailed sketch of the arrangement with tube lengths and how the load attaches.

desertfox

 

[k75ks]

The 6 X 8 tube is the current load bearing member and is known ok.

Our change is to the upper section and to be sure the wider end plate won't bend. I used the current designs' stress equations, with the new dimensions. I'm just wanting to know if I'm applying them right.

Enclosed shows cylinder pushes end plate and tube up from inside it.
Thanks again for your patience & help.

 

[desertfox]

Hi k75ks

I see now what your trying to analyse ie bending of the end plate, well as a direct comparison with the earlier design I would say your correct, however theoretically the plate is not a beam and to correctly calculate stresses it should be done following formula in O'roarks formula's for stress and strain, if you have had no problems with the earlier end plate design then this should be okay.
When taking the moment for the force acting it should be taken to the centre of the ram and not to the edge of the ram diameter.

desertfox

 

[k75ks]

Ah, so the previous calcs weren't quite right either.
I'll pursue O'Roarks' formulas for a better answer, but with Some confidence that we're enough as is.
Thanks so much for your time & consideration.

 

[desertfox]

k75ks your welcome

desertfox