Die Design Help for Flare Die

[Brett W]

Tonight I made this shape with a janky setup. I had a round ring on my press and used the tapered cone I use for tube end forming/flareing.

I just cut a 2.5in hole in the .062 aluminum sheet and clamped it to the ring. I bored the hole in the ring to 3.150in and put a nice radius on the leading edge. I think the hole needs to be a little bigger.

Since the goal for this is to slip over a 3in tube to make a nice looking flange to weld to, I would like to make a die to repeat this.

Question:

Since I am stretching a 2.5in hole to 3in, should the initial portion of the die just be tapered and then square off as the last step as it seats into the bottom die?

How big a diameter does my die need to be? I was thinking if I use 4in round bar for the die that will flatten the flat portion of the material after it has been stretched.

Any reason to use anything other than 1018 or should I use 4140? I am not making millions of these, so I don't know that die wear is a huge concern. The current setup doesn't assure very straight flares as its not perfect as far as centering goes.

 

[AD Design]

Never tried using a forcing cone, always used a punch/die form that matched but we'll try to work with what you have as it may work for your purposes. First off:

1)Have you done any reading about punch/die geometry for drawing, stretching, or is what you're doing both?

2) For what you're doing I don't know how "nice" you'll want the finished operation to be

3) The entry radius for the punch and the die is somewhat critical. Read up on this, it's not long reading.

4) There doesn't appear to be any polishing done to the entry radius on the die, polishing (in the direction of material flow) makes a big difference with the result. Excessive drag/friction leads to tearing of the material, insufficient friction (also from too large a radius) places the material under compression rather than flow and can lead to buckling/wrinkling.

5) If that's material stuck to the punch/die (can't tell from the photo) then you also have insufficient lubrication going on and material has galled/welded itself to the punch/die. Aluminum is one of the most likely to do this in draw applications. Use something for lube, even lard or soap is better than dry forming.

6) I don't think you need to use anything other than what you've already started with (1018) but you will need to experiment some to obtain the results you're looking for. Clamping, surface finish, radii, and punch geometry all make a big difference. In the end it's really about what YOU want the results to be. A larger material hole will decrease your wall height so start with what the end results needs to be and work backwards from there.

7) If it's off center how are you locating it?

8) How deep are you driving the punch? Is there a way to make depth entry repeatable? If not you're guessing.

Start with the radius polish (in the correct direction) add some lube and see what you've got before changing the tooling. It may work well enough as is for your purposes. If not, we'll go from there. Good luck

 

[Brett W]

Thanks for the feedback.

The die portion is a driveshaft damper from a Jeep, LOL, I was using it for a press tool and happened to test this theory. After machining it out to get the hole to open up enough to fit over the aluminum tube, it sorta works. Its some kind of gross cast iron as it comes off not as chips, but little balls/granules.

I use a hole saw to cut a 2.5in hole in the 16ga aluminum sheet. Pretty sure its 5000 series. Then it gets hit with a torch to make sure its dead soft. Then I drop the sheet over the cone, and lay the die on top of the sheet. I kinda eyeball it for center (which is terrible). Then clamp the four corners to keep the material from becoming a taco chip. Then press until the die kinda bottoms on the forcing cone. Basically when the die stops traveling easily I stop. I am using white lithium brushed on the die and cone.

I have NO die experience and found a couple of links to books, which I am gonna order, but figured there was a cleaner way to make these features and some of ya'll with a decade or two of experience might have some tips.

Guess I am happy with the finish as it is currently. I can always sand the tube and the plate before I weld them. The sheet is just a basic tab to hold these tubes in position as brake ducts on a track car so it gets hidden behind the bumper and never seen again till they get damaged. The Cast iron donut doesn't polish super well, but it doesn't seem to be marking up the form when I press it.

Also am I drawing or stretching this? I was thinking more about it last night and it seems like I need an upper and lower. The lower can have the final shape and radius and a "centering" hole. The upper portion would have the centering lug, then some sort of tapered section that could then square off for the final "coining" of the operation. That could push the final radius into the top edge of the aluminum.

 

[rklopp]

Oddly enough, I was researching this operation early today. This link seems to offer some good starting ideas: Metal Stamping And Die Design: Forming | MachineMfg

 

[boslab]

Used to be a rubber job on Ali sheet for airframes, never got involved so very limited knowledge,
Mark

 

[Brett W]

Oddly enough, I was researching this operation early today. This link seems to offer some good starting ideas: Metal Stamping And Die Design: Forming | MachineMfg

Bad ass. Thanks. I will start reading up on that.

 

[AD Design]

Bad ass. Thanks. I will start reading up on that.

You're doing good by educating yourself, further questions from you will also be better informed questions.

In reading back through your post I don't feel that using a torch to soften the material is of any benefit and may allow unwanted defects to show up if it is softer. Uniform material characteristics lend to producing uniform surfaces/shapes. A torch may/may not produce uniform shapes/surfaces and have localized defects. Steel parts get produced with no trouble, aluminum is softer than steel. Report back when you're ready.

 

[DDoug]

I think this was covered in the past, IIRC one thread dealt with doing a stainless
tank, in place using a hydraulic pull cylinder.

 

[Brett W]

You're doing good by educating yourself, further questions from you will also be better informed questions.

In reading back through your post I don't feel that using a torch to soften the material is of any benefit and may allow unwanted defects to show up if it is softer. Uniform material characteristics lend to producing uniform surfaces/shapes. A torch may/may not produce uniform shapes/surfaces and have localized defects. Steel parts get produced with no trouble, aluminum is softer than steel. Report back when you're ready.

I figured to make sure the aluminum was soft enough not to tear. Since this was the first one I wasn't sure how much it would move/stretch without tearing. This was 5052 H32 Aluminum sheet. I'll experiment with just the sheet as is and see what happens.

 

[AD Design]

Soft doesn't always mean it won't tear, there are other reasons for it to tear. Trapping material under compression (friction, excessive radius, etc) can cause the material to tear because the material doesn't flow into the die. I understand your thought process but better to work the tool design first rather than use a crutch or workaround in the beginning. Gimmicks are for when the tool is all it can be and needs that last little bit of help to cross the finish line. When material properties change will the gimmick still work? Your requirements don't appear to be stringent and experimentation by you will likely be short to get what you're seeking.