making a Platen press from a H-frame Hydraulic press 2

[roadrider42]

Ok,
I'm a software engineer, not a structural engineer, but I have a question about the strength of plate steel. I know there are many types of steel out there, but let's assume the "default" stuff you would buy from "Joe's steel" down the road..ok I have a 50 ton H-frame hydrualic press. what I'm trying to do is take the force from the 3" diameter ram and distribute it over a 48" X 14" area. What thickness of steel would be required to distrubute the actual usage weight of 43 tons evenly over this area with no/minimal bending?

 

[Metalguy]

First, all steels have approx. the same "stiffness" below the point they permanently bend/yield. The big questions are what is under the steel and how much bending can you tolerate? The 4' dim. is the tough one-it's long, and the load is high.

 

[roadrider42]

Hey Metalguy,thanks for replying......
the steel will rest flat atop a concrete mold made from 4000# concrete, with rebar, about 6 or 8" thick. this top/female part will rest on maple veneer plies (skateboard manufacture), and that in tern will rest on the male concrete mold. this male mold will sit flat on the press's bed. My concern is any bending will crack the concrete, and not give an even distribution of weight across the mold.

 

[Metalguy]

Hopefully the rebar is in the lower section of the concrete, just above the mold cavity. I think your easiest and cheapest way to go is to use several plates-welded together. The top one could be ~12" X 6", and ~2" thick. Then use 2 more of bigger size until you get the 48 X 14. You will end up with 6" of plate right under the ram. You should be able to find scrap steel of these sizes very cheap. Someone who has the time/knowledge could work it all out with math, but I'd feel confident that the above arrangement will be fine--unless all the rebar is up in the top of the concrete!

 

[roadrider42]

Thanks Metalguy....I talked to a local steel shop and they suggested 4" X 14 X 48...it was like 700lbs and 500.00 for the plate (yikes!) Another thought I had was to use 1 1/2" plate, with three 1 1/2"thick X 4"H X 48"L plates welded vertically to the bottom plate, and then a small square welded on top for the ram to press on, it would look like an "E" on it's back, looking at it from it's long end. Any comments? Thanks

 

[Metalguy]

Yes, I think you're on the right track. Rigidity is the key, and you get that in a hurry with vertical spacing.

I wish I had the time to calculate the deflection-I'll ask my wife-she's the mech. eng. of the family!

 

[lesliehowell]

roadrider,

Go to my web site at the end of my email and there you will find an email address for me. Once I have your email address I will send you some cut sheets that I have used for years to calculate stress. They will be in PDF format. So send me an email. Some day I am going to have to figure out how to post some of these things on this site for everybody.

Sincerely yours,
Leslie H. Howell Leslie H. Howell

http://www.howellconsulting.com