[slashmaster]

I know there is a such thing as a cnc tubing bender. I was just wondering if there is a such thing as a cnc machine that can fold a piece of sheet metal any way you want? Like maybe make a fender? Or is this only possible by stamping?

[Cartierusm]

No, I don't think so; there are cnc sheet benders but they only bend angles. That would be cool, but not possible.

[austin.mn]

Actually, there are several computer controlled sheet benders out there. I remember watch a video at one point that was pretty impressive. That being said though, I don't think that you are going to bend a sheet metal fender with a press brake even if it is controlled with a computer. On the other hand, I did read about laser bending. They took and heated a sheet of metal up specificly here and there and wallah 3D sheet metal bending.

[One of Many]

No such thing as a CNC fender bender if the part has a 3D profiled surface. That would take a stamping press, which could still be CNC controlled.

Check out Youtube. They have all kinds of robotic industrial equipment in action.

DC

[ame="http://www.youtube.com/watch?v=NaJQrjgolKs&feature=related"]Trumpf and bot[/ame]

[mc-motorsports]

I know there is a such thing as a cnc tubing bender. I was just wondering if there is a such thing as a cnc machine that can fold a piece of sheet metal any way you want? Like maybe make a fender? Or is this only possible by stamping?

Motorcycle fenders? Or car fenders?

If you want to make motorcycle fenders, you can make a "slip roll" with round dies and form motorcycle fenders in halfs and weld them together.

Usually motorcycle fenders are either hand rolled in dies as mentioned or stamped in halfes and welded together.

Car fenders are just stamped out using multiple stamps, couldn't do that on a shop press though.

There is a shop not far from me that makes replacement fenders for RollsRoyce restorations, they use an english wheel and they didn't say how long it takes, A LONG TIME I'm sure.

[PixMan]

Nothing out there that I know of yet, but the first guy to come up with a CNC-controlled version of a english wheel will be a very wealthy man.

[zephyr9900]

It's been done, kind of. OCAS has developed a machine that uses a stationary "spindle" to progressively form metal over a CNC'ed wood or urethane buck. I have a PDF and video from them from 2006, both of which are too large to upload here (8MB and 14MB)

edit: This is a link to a much smaller video that shows the technique briefly.

The machine looks very heavy-duty and expensive.

Randy

[BobWarfield]

There is a relatively new process called "incremental sheet metal forming" that is done on a CNC mill:

http://www.journalamme.org/papers_am...a1f4372676ee49

Here is a really cool video of sheet metal forming:

[ame="http://www.youtube.com/watch?v=GxysBla3NyI"]YouTube - sheet metal forming[/ame]

It would take quite a machine to make an automobile fender, but a hood scoop, wheel flare, or something similar should be doable on a reasonably sized machine.

Cheers,

BW

[mc-motorsports]

Good call on the video! Kind of a diffrent twist on metal spinning, huh? Any more details on the process? I'm guessing there is a little more to it than a 3 axis mill and a chunk of sheetmetal....

[mc-motorsports]

It's been done, kind of. OCAS has developed a machine that uses a stationary "spindle" to progressively form metal over a CNC'ed wood or urethane buck. I have a PDF and video from them from 2006, both of which are too large to upload here (8MB and 14MB)

edit: This is a link to a much smaller video that shows the technique briefly.

The machine looks very heavy-duty and expensive.

Randy

I'm confused. This process looks like 3d printing, but they said "metal". The video Bob posted looked like a 3d metal spinning, just in reverse of what I know of metal spinning, or was it?

I guess I'm stuck in the stone age. I don't work for a high-tech company anymore, so I don't get to go to customers and see any of the new technology, equiptment and processes like I used to... sucks! That's the one thing that I do miss... That and paid vacations,(the kind where you say **** work for 3 weeks) miss those too!

[zephyr9900]

The video Bob showed is the same technique as the OCAS video I linked to, except the spindle is turning in his case.

In both cases, they first CNC machine a buck (male form) made of wood or plastic. The sheet of metal is clamped over the buck, and the spindle pushes the metal over the buck in an operation like waterline machining. Notice the lubricant, which I assume is the same as used in deep-draw stamping.

It's a lot like vacuum forming, but done mechanically instead of with heat.

Randy

[austin.mn]

Ok, So who is going to be the first on the Zone to do it and teach us all?

There is definitely a few projects that I would like to do with that technique, but I will probably be short on time for the next month or two. It does look like a guy with a standard three axis machine should be able to do it though.

[will gilmore]

is the sheet drawn down over the buck or does it just slide as it is pushed down by the tool?

[zephyr9900]

It looks like the sheet is mounted on a frame that just slides vertically by gravity.

Right at the start of BobWarfield's linked video you can see four vertical rods and dieguide-type bearings holding the frame.

BTW, the OCAS webpage has a broken link but here is their PDF brochure. Unfortunately their photos are too zoomed in to see the details of the corners of their frame.

Randy

[will gilmore]

pretty cool. great for those sharp shapes which are hard to shape traditionally. what kind of machine ridgity do you need to do something like that?

[slashmaster]

Wow this is GREAT! So you do need either the positive or negative of the die but you don't need a big metal press to stamp it! I guess I just have to build 2 metal frames the size of the sheet metal to clamp the sheet while I make it? Does anyone know what that brown stuff is that they used to make the die in that video zephyr9900 left a link to? What does that stuff cost?

[will gilmore]

I think having a positive would work much better as the weight of the sheet and the frame would help "pull" the metal over the form. Where I'm from we call that brown stuff "wood" They are probably using something like MDF.

[zephyr9900]

I think that MDF would work great, Will, but from the looks of the material in the OCAS video they are using a polyurethane tooling board like Renshape or Last-a-Foam

I was thinking about the male/female mold last night too. I think that using a male mold will help by being able to draw/stretch in more material from the surrounding sheet, but a female mold will immobilize the sheet once you start drawing down and cause all the stretching in the middle. The male mold will probably give a more uniform thickness to the part.

OCAS's machine is a pretty heavy-duty portal design--the X and Y axes are each mounted directly to the base structure. The University of Ljubljana guys in Bob's video are using a Deckel DMU 50 T milling machine, which is pretty substantial.

But if I were trying this (and who says I won't maybe? ) I'd probably start experimenting with annealed aluminum roof flashing and use my Tormach, itself pretty stout for its size.

Randy

[slashmaster]

Thanks for the replies everyone! This really excites me! I totally thought cnc milling was only for carving a solid piece of stock. To find this out is really great news even if I do have to waste some material to make the buck form.