question about large punch presses
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  1. #1
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    Default question about large punch presses

    I spent the last few days(off and on) cutting out a 2.5" wide by 6" long slot in a piece of 2.375" thick A36 plate. Made me wonder if there exists a press big enough to punch out a slug that size? Never seen or heard of such things but have not seen everything that's out there.

    Dale

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    The sides of the slot would not be anywhere near straight. Using the 10% clearance rule, you'd need almost a quarter inch of clearance between the punch & die. If that's not a problem, then you'll need lots of tonnage & one hellacious punch and die set. How many you got to do?

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    Yes, there are some very large presses out there. Plus what Pyro said, your slot would look like crap.
    JR

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    Thanks for the responses Anybody have a way to calculate what kind of tonnage it would take to punch this out? I know it would not be practical, but is it feasible?

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    I do not think it is practical or feasible. You would need at least a 1000 ton press and some major hearing protection. I once punched a 1.25 diameter hole in 1 inch thick hot rolled steel using a 400 ton press. It did pierce the hole but the punch broke after piercing. The slug hammered out the bottom of the press and shot across the floor. When I did find the slug about 5 minutes later it was still smoking hot. The slug measured about .100" shorter in length and was a lovely hourglass shape, kinda like an air gun pellet. The noise it made was like a shotgun blast. Never tried it again and hopefully I will never have to. The boss saved the slug and used it as a desk ornament.

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    I came up with an EWAG of 3800+ tons, but that was early this morning. guessed that the ends were radiused.
    IIRC I used a 20" perimeter.
    Perimeter of slot * thickness * 80 tons.
    JR

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    Quote Originally Posted by gwbolton View Post
    I do not think it is practical or feasible. You would need at least a 1000 ton press and some major hearing protection. I once punched a 1.25 diameter hole in 1 inch thick hot rolled steel using a 400 ton press. It did pierce the hole but the punch broke after piercing. The slug hammered out the bottom of the press and shot across the floor. When I did find the slug about 5 minutes later it was still smoking hot. The slug measured about .100" shorter in length and was a lovely hourglass shape, kinda like an air gun pellet. The noise it made was like a shotgun blast. Never tried it again and hopefully I will never have to. The boss saved the slug and used it as a desk ornament.
    Don't know what you did wrong, however what you describe has been done for
    a very long time, and even in multiples, all in one stroke.

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    What's that you say ?

    You can't forge rear axle spindles cold.....that
    would be crazy....

    https://www.sae.org/publications/tec...ontent/620134/

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    How about a 12 inch hole in a 12 in thick disc? 5000 ton press.kimg0121.jpg

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    Quote Originally Posted by JRIowa View Post
    I came up with an EWAG of 3800+ tons, but that was early this morning. guessed that the ends were radiused.
    IIRC I used a 20" perimeter.
    Perimeter of slot * thickness * 80 tons.
    JR
    Isn't that formula Dia*thickness*80? When you use perimeter directly you need shear strength, which would be 25 tons/in2. That trims it to only 1200 tons. That die set will be so cheap you better order a spare.

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    Quote Originally Posted by rbdjr59 View Post
    How about a 12 inch hole in a 12 in thick disc? 5000 ton press.kimg0121.jpg
    No fair, you got the electrons all excited in the part, makes them loosey goosey.

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    Probaly make a lot more sense to just burn them in or water jet - plasma. both will do that very very easily with no excitment or so much value in a press it makes no sense.

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    Quote Originally Posted by gbent View Post
    Isn't that formula Dia*thickness*80?
    That's why I said EWAG. I knew is was something times something else.
    JR


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