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question about large punch presses

swellwelder

Stainless
Joined
Sep 21, 2002
Location
Valley City, ND USA
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
 
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?
 
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.
 
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
 
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.
 
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.
 
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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