Home sheet metal stamping help needed!!!

I'm going to post this message to all groups that I feel may be able to
help. Bear with me, I'm ignorant, but ambitous. I'm tryng to make
something similar to a cookie sheet. A little larger radius (2 1/2")on
the corners and about 1 1/4" deep out of 22 ga. cold rolled steel. I've
built a "press" using I beams and 25 ton bottle jacks to do the
job.(Keep in mind if I could afford to job this out, or pruchase a
press, things would be different.) Anyways, I've managed to make the
part except for the corners wrinkle badly. I'm in the process of
casting the female to allow me to use binders. The question is where is
the best place to bind the blank? In the corners, or along the
straights? Any help, opinions, suggestions, ideas are appreciated! I'm
doing this with determination and junk layin around the yard. Buy a 10K
press, hire a die maker...etc. are not the answers I'm looking for.
Unless someone is willing to produce this for less than a grand. Thanks
again!!

 

How about buy a $40 book ~
http://www.amazon.com/Sheet-Metal-F...ef=sr_1_1/102-8222904-3360145?ie=UTF8&s=books

Anyway, to cut to the chase, you start with big corner round on a shallow
draft and gradually "bring it in" dimensions get smaller, radiuses get
sharper, drafts get steeper (just because draw size gets closer to form. So,
in two or three draws, you can get localized stretching without the
wrinkling.

David Janes

 

If you start your forming process of a 12 by 18 cookie sheet with a 24 by 36
first draw, you might be clamping it at 25 by 37 inches. For subsequent and
decreasing draw dimensions, the clamping plate does not change. You just
keep using smaller draw frames (with smaller and smaller corner radii) until
they get to the desired size ~ the more steps, the less likely to wrinkle in
the corners.

David Janes

 

Also, re-drawing with different sizes rads may not be required, but
just the amount of binder tonnage needs to be increased., along
spotting the corners to allow the material to thicken to a point just
before wrinkling occurs.

 

Yeah, exactly, it's a highly technical process which is why I mentioned
buying a book, taking a course, getting a degree, whatever, something,
anyway, more serious than popping in here for a freebe!! And why I stuck to
some cartoonish basics. I took that long-forgotten course in a tooling
apprenticeship and learned 10 times that from guys that did it every day.
But, nobody's experts here and if we were, we'd be onsite, charging big
bucks just to look at your setup. But, if you're using bottle jacks, buy
more of them, in fact, double the number and yeah, definitely lock down
those corners plus one on the each short side and two on the long sides or
something proportional. Anyway, the long sides pulling is not as big a
problem, for wrinkling, as the corners pulling.

Good luck,
David Janes