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Metal Stamping/drawing

Discussion in 'The Hokey Ass Message Board' started by scootermcrad, Feb 22, 2011.

  1. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,382

    scootermcrad
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    Sorry this is getting so high tech. Just figured it would be clearer to draw it this way than to sketch and scan.

    The part would look like this after trimming everything up. I'm not looking to have the dies do any trimming. Would do it manually....

    [​IMG]
     
  2. slik
    Joined: Jan 11, 2008
    Posts: 183

    slik
    Member

    to big of a blank. there is not enough room to put the metal when it is bent. you were better off with the smaller piece and the rubber "plate" that the other guy mentioned.
     
  3. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,382

    scootermcrad
    ALLIANCE MEMBER

    That was my initial thinking as well. Seems like it would be easier for the material to draw since there would be less pulling from the metal around it that would ALSO have to stretch to accommodate the shape. Trimming would be a hell of a lot easier as well.

    Again, though. Does the "rubber plate" go between the blank piece and the male die?? I still can't quite visualize this. The videos previously linked up didn't explain anything more than not using a male die at all, but just a female and that was for shallow embossing. If I have the rubber between the material and the male die, I would have just open up the female die to allow room for it.

    Rubber inner-tube material, maybe??
     
  4. hasty
    Joined: Jul 5, 2009
    Posts: 1,411

    hasty
    Member

    Fascinating thread. A post to bump it back to the top
     
  5. Sealed Power
    Joined: Mar 11, 2005
    Posts: 627

    Sealed Power
    Member
    from TN

    Looks to me like it would be better to turn it over.

    Female die on the bottom them you could place some dowel pins for alignment of the blank.

    You should be able to pick up a cheap die set with the pins already installed just bolt your male and female parts to the existing die set.
     
  6. Sealed Power
    Joined: Mar 11, 2005
    Posts: 627

    Sealed Power
    Member
    from TN

    Something like this, they come in a four post version like your drawing. I have some I have picked up as cheap as $20.00 just depends on your area and how big a one you need.

    You can find them cheaper than you could buy the material to make one most of the time.
     

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  7. budd
    Joined: Oct 31, 2006
    Posts: 3,478

    budd
    Member

    interesting part, the rubber or urethane with a plate on top has the same effect as a die cushion, the urethane acts like a spring and as such you would not want to compress it more then 25% of its hight, so if your drawing 1/2" your urethane should be 2", but also you should think about having your blank being clamped before you even start to form it, so if you made your plate/stripper out of 1/2", end milled some 3/4" round pockets all around your male T to hold some 3/4" urethane die springs 2-1/2" long, make your male T 2-3/4" tall you should be in business, your stripper plate will be 1/4" proud of your T so you will have some clamping going on before the forming process starts, urethane die springs come in different stiffnesses, or you can skip the urethane and use old valve springs.
     
  8. Ok, I'm sure the others will set me straight, but, just like when you're punching a louvre, the critical profile as such is the male, with the female not requiring the matching shape as the male, just a recess for it to go into, and a controlled edge(in relationship to the male die) to define where the shape starts/finishes.
    The female could easily just be a simple profiled (or milled) recess with a compressable element in the recess(such as rubber) to assist with retaining the plate, and reducing the influences that make it want to ripple as such.
    Again, think of it as when your punching a louvre, you need to make sure the test piece doesn't move, however, the female die just defines the start/finish of the change in shape, with the male die forming the desired profile. If you add a compressible element into the female recess, it will assist in keeping the shape stable, even if you don't press the whole way, and effectively sandwich the plate to the male die, without needing to have a perfect gap like you would need to calculate if you had a rigid female die.

    I hope I haven't made it sound more complicated than it really is, appoligies if I did.

    cheers,

    Drewfus
     
  9. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,382

    scootermcrad
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    Hmmmm... I think I see what's being said here.

    Basically, what I drew for the male die in this case would be left alone, but I would change up the female to be nothing more than a T-shaped recess or pocket that would be deep enough to allow for the rubber cushion to sit in the bottom of the die. Or am I confused still? HA!

    Sealedpower... Are you implying simply buying a die set like you've shown and just modifying the profiles instead of starting from scratch or am I missing what you're saying?

    And while on the topic of materials... Suggestion for the pad/rubber? Durometer??
     
  10. Crazydaddyo
    Joined: Apr 6, 2008
    Posts: 3,343

    Crazydaddyo
    Member

    The plate with a rubber pad goes on the bottom of the die and "surrounds" the punch (male die) In the open position the pad would be slightly above the punch.

    You will have to lengthen this height of the punch to accommodate the pad and it's travel.

    The blank would be a developed shape to allow for stretch and compression.

    I can help you with all of the above. You do your magic on the Photog and tech.

    .
     
  11. Sealed Power
    Joined: Mar 11, 2005
    Posts: 627

    Sealed Power
    Member
    from TN


    No, you don't actually modify the die set. You make your parts with the shape bolt onto the die set. If you look at the picture I posted you can see a square outline where something was bolted on to it.

    The die set takes care of the alignment of the two pieces. When your thru with it you can bolt something else on and re use it.

    It won't do any better job than what you've drawn just thought it might be cheaper and easier.
     
  12. banzaitoyota
    Joined: May 2, 2004
    Posts: 547

    banzaitoyota
    Member


    What is the correct term for this device? Die Holder? Die Fixture?
     
  13. Sealed Power
    Joined: Mar 11, 2005
    Posts: 627

    Sealed Power
    Member
    from TN

    Die set is all I've ever heard them called. Danly is one of the bigger manufacturers.

    They are pretty pricey new but they are usually cheap if you can find a used set.

    They come in all sorts of sizes. Here's a link to some on ebay.

    http://shop.ebay.com/i.html?_nkw=da...nly+set&_osacat=0&_trksid=p3286.c0.m270.l1313

    If you have a local stamping place they usually have some old ones that they will sell cheap, at least around here.
     
  14. chaddilac
    Joined: Mar 21, 2006
    Posts: 14,021

    chaddilac
    Member

    Actually I do bubba!! I do my best design while I'm looking at the back of my eyelids and can't think straight enough to write it down... and I'm always thinking about the coupe and what I need to buy or build!! :D
     
  15. landa
    Joined: Jan 18, 2007
    Posts: 39

    landa
    Member
    from california

    1 inch D2 for the die soft no need for heat treating you will be able to sharpen or mill when it needs it. if you need a pad I would use some 1/2 inch wood to start with. die clearance I would go with a fraction size end mill and use round stock for the punch. 4, 1/2 inch diameter dowel pins. I would start with 8% of the material thickness. or the closes fraction to accommodate the die clearance.
     
  16. Toner283
    Joined: Feb 13, 2008
    Posts: 1,327

    Toner283
    Member

    Scooter,

    Most draw dies for deep draw parts are made of 3 separate sections. There is a male form or punch (usually the lower section), a female form (usually the upper section) and what in our shop is called the blank holder. The blank holder rides on cushion pins that are on a die cushion pad that is below the main part of the press. It is kind of like a giant adjustable shock absorber (the die cushion is not shown in my drawing but is shown fairly well in the you tube video Budd posted). You can tune the cushion pad for how hard it is to compress. thicker/stronger material requires a stiffer cushion pad. In the drawing below I have shown a cutaway of a the draw die. The blank holder fits totally around the lower die form. I have also heard it called a draw ring.

    the blank holder has a draw bead that matches a mirror image bead in the upper die. this is to grab the steel sheet & allow it to gradually slide through between the upper & lower draw beads & form the part. The upper die closes against the blank holder and grips the steel sheet. then as it closes farther it draws the steel sheet down over the male form. the draw beads are pretty precise. too much grip will cause the steel sheet to tear or crack as it forms and too little grip will allow the steel sheet to bunch up, wrinkle & fold. (steel sheet omitted from my drawing for clarity)

    Think of it like a plastic grocery bag that you lay across your knee and then smooth it down with your palms. it will still be wrinkly and folded in places. this is a draw with no blank holder or cushion pad. now take the same grocery bag & grip it in both hands and then stretch (or draw) it down over your knee while holding on to both sides of the bag. Now there are very few wrinkles & folds in the direction of the draw (where your hands are).

    The guys who are suggesting a piece of rubber to help control your blank (steel sheet) are correct. you need some way of controlling the blank as it forms so that it stays where you want it to and does what you want. I believe that the basic die you have laid out will work well with a bit of trial & error for the rubber part of the die. the mass production dies I am used to have guides to keep the steel blank centered front to back & side to side but since time is not an issue you should be able to set the blank in by hand & close the dies gradually until the steel is gripped so that your blank does not move much.

    Hopefully this clears up a bit of confusion & helps you to understand a bit better. It is a bit difficult to explain without the press right in front of us. My drawing looks like I drew it with a broken crayon next to your drawings but it is the best I can do on the computer.

    [​IMG]
     
  17. The37Kid
    Joined: Apr 30, 2004
    Posts: 30,628

    The37Kid
    Member

    Great thread! Glad you don't need to find a Pratt & Whitney Type BG-3 Keller Machine.:D
     

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  18. Inline
    Joined: May 13, 2005
    Posts: 261

    Inline
    Member
    from Ohio

    I had to make a collector for a motorcycle exhaust one time. It was made out of stainless in halves and then welded together. I had to make a female and male die which looked very similar to what you have drawn up Scooter. The female die was 8" by 8" and it had 4 tapped holes in the corners well away from the the cut out area of the die. I bolted the 8" by 8" 20 ga stainless sheet to the female die with these holes. Basically, the bolts acted like the cushion block in Toner's picture to hold the blank in place and allow it to be streched. I placed the male die on top and pressed it in a large arbor press.

    The female die was made out of aluminum and male die was out of cold roll steel. For the 8 parts I made, it worked great. I wish I took some pics of the process. The only one I could find was a crappy pic of the finished part on the car. It was for a FSAE car in college.
    formula_075.jpg
     
  19. pitman
    Joined: May 14, 2006
    Posts: 5,148

    pitman

  20. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,382

    scootermcrad
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    Toner283,
    Actually I really understand your drawing just fine! Probably more clear than the 3D crap I drew. HAHA! :D And I totally get the concept. It's similar to hammer forming with female receiving die and a surrounding plate that clamps the piece in place, but has a hole that matches the outline of the shape so a hammer/mallet can be used to beat/form/stretch the metal into the die. I totally understand the process shown in that picture.

    I need to restate something here... This is not for mass production of a a finely tuned reproduction part, that I will be selling, or something. Investing money into some expensive materials to make these dies is NOT realistic and completely out of scope. For those recommending tool steel to make these, like D-2, I think you're sort of missing the point of this "DIY" project. D-2 and similar materials are pretty expensive. Not trying to be a cheap-skate, or anything, just being realistic. If other materials can get the job done for the low quantities I'm making, it has to be done. Just for the D-2 materials I would be looking at $350 or so to have enough 1" plate to make two male and two female dies (two different parts). And that's if I only make two-piece dies. If I make 3-piece dies, as suggested above, that cost only goes up. I would have no problem with that if it were making something I was going to make a ton of and selling for lots of money, but in this case it's about doing it on an affordable budget for a project in the shop. IF I can achieve decent results from simply machining this out of carbon steel and hardening the surface, I am open to this. This is not a part for an aircraft that is intended to break that sound barrier, or be a reproduction part of some kind. I'm simply making a bunch of one-off parts that need to look similar in shape and it seems I would get the repeatability of the shape by making dies. But maybe I'm wrong...

    If I have to, I will switch modes, and hammer form these little parts, but I would rather not. Cost is a factor, time and labor is NOT.
     
    Last edited: Feb 23, 2011
  21. MDF and just hammer form em................................
     
  22. Crazydaddyo
    Joined: Apr 6, 2008
    Posts: 3,343

    Crazydaddyo
    Member

    Scott,
    If you don't have the means to draw the part at your shop, We can do it at mine.

    [​IMG]
     
  23. budd
    Joined: Oct 31, 2006
    Posts: 3,478

    budd
    Member

    heres my cross section, the upper and lower plate are 3/4", you kinda need this thickness to allow you to machine pockets for the die springs, if you use 1" dia urethane die springs with a 1/2" hole in the center they make nice motor mounts when your done, i have some on my pickup, i havent drawn the top female plate but i think you can figure that out, i would place some urethane in it as well to pop your part out when its done, lubing the part before forming is pretty impotant, you will get pickup on the female die and it will want to hold your part.
     

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  24. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,382

    scootermcrad
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    HAHA! Sweet!!! :D
     
  25. You could make the blank longer and wider,
    then locate the material on a couple small pins.
    After forming, just trim to length.

    Coat the part with STP to help it form without tearing.


    You will need clearance for material thickness on each side.

    One problem you will have, is different spring back for different materials. Stainless parts might require some rework.
     
  26. Toner283
    Joined: Feb 13, 2008
    Posts: 1,327

    Toner283
    Member

    LOL, that is one of the presses I work with everyday - I shot that video. Scooter, you will need one hell of a third bay to put that sucker in. the footprint of it is about 60 feet long & about 40 wide at its widest. The top of it is about 45 feet in the air & there is another 15-20 feet hanging below the main floor level. those windows in the front of the press are not quite 4 feet wide to give you an idea of the size of the beast.

    Oh, & it will put you over budget just a little.:rolleyes: IIRC the price tag on that press was about 10 mil installed & running. at this point it has somewhere around 40 million strokes on it (mileage for presses) and is about 7 years old.

    If you buy one I can come down & run it for ya, I can run it with my eyes shut.:D

    Here is an overview shot.

    [​IMG]
     
    Last edited: Feb 23, 2011
  27. pitman
    Joined: May 14, 2006
    Posts: 5,148

    pitman

    Figured it was the only rig that could out-pace Sibley! :D
     
  28. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,382

    scootermcrad
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    HAHA! Nice!

    I was thinking either the large arbor press we have or making a press with a bottle jack. Little slower and just a wee bit smaller. :rolleyes::D
     
  29. Two pins to guide the tools should be enough. It'd just have to be more precise if you did more...
    And I'd make the blank big enough so it's sticking out to the side of your die.
    This way you can easily remove it in case it sticks to either side of the die after forming.
     
  30. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    Someone asked to see the simple louver die I made for use on small panels in a big bench vise.

    It is hinged like salad tongs, with a welded end on two 1/8" thick alignment plates. I was going to use a house door hinge but those have slop. So I welded it.

    The female die is just 1/8" thick band steel standing on edge in a D shape outline, welded to one alignment plate.

    The male die is 1/4" thick hand ground to shape. I drilled 2 holes through the other alignment plate so I could plug weld to the back of the male die piece.

    I was not pre-slitting the louver openings; if I knew how to pre-slit real accurately on each louver, it would be better and last forever. It did start to dull at the cutting edge as I finished the two cowl panels
     

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