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Sheet metal bends - IV9

18 REPLIES 18
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Message 1 of 19
dclassen
595 Views, 18 Replies

Sheet metal bends - IV9

For all you sheet metal in Inventor buffs, help please!

I am having trouble making sense of the flat pattern size calculated by Inventor on a sheet metal part using the flange feature to create a bent leg. For example, I have a formed 3/16 plate part, with a 12 3/16" leg O.D., and a 5 1/4" leg O.D., bent at 90deg. The shop would normally manually calculate a flat pattern for this at 17 1/16, adding up inside dimensions, and making no adjustments for bend radius. My understanding is that our shop mostly uses a "knife die" to bend with, so it is a very minimal bend radius. But when I drew the part, I left the bend radius set to "thickness", so 3/16, and it calculated the overall flat to be 17 1/8.

Any help explaining how Inventor and a shop can work together on bending sheet metal would be appreciated. Thanks everyone.
18 REPLIES 18
Message 2 of 19
mount_mordor
in reply to: dclassen

Many people set up bend table, because inventors default is not close enough for manufacturing purposes. Do a search in IV help, and it will tell you more.
Message 3 of 19
jerr72
in reply to: dclassen

I opened the file, looks good here. I deleted the flat pattern, recreated it. I am posting a view.
Message 4 of 19
Anonymous
in reply to: dclassen

Inventor does a very good job of calculating flats in my book. If our parts
don't bend to Inventors numbers then the tooling or the machine are wrong.
You can't believe how much unusable tooling is still in use out there be
cause the operator does not know what is good and what is bad. Good press
brake training is imperative to both operator and designer.

Matt

wrote in message news:4827783@discussion.autodesk.com...
For all you sheet metal in Inventor buffs, help please!

I am having trouble making sense of the flat pattern size calculated by
Inventor on a sheet metal part using the flange feature to create a bent
leg. For example, I have a formed 3/16 plate part, with a 12 3/16" leg
O.D., and a 5 1/4" leg O.D., bent at 90deg. The shop would normally
manually calculate a flat pattern for this at 17 1/16, adding up inside
dimensions, and making no adjustments for bend radius. My understanding is
that our shop mos
tly uses a "knife die" to bend with, so it is a very minimal bend radius.
But when I drew the part, I left the bend radius set to "thickness", so
3/16, and it calculated the overall flat to be 17 1/8.

Any help explaining how Inventor and a shop can work together on bending
sheet metal would be appreciated. Thanks everyone.
Message 5 of 19
Anonymous
in reply to: dclassen

Hi! Inventor sheet metal computes unfold length in two ways. By default, it is computed by K-factor (a unitless number between 0 and 1). This factor defines where the neutral bend zone is. Please take a look at attached part.There is a 2in long face and a 1in leg. Inventor first computes the straight segment length:

2in - 2*thickness=1.76in for long face
1in-2*thickness=0.76in for the short leg.

The tricky part is calculating the unfold length of bend area. Take a look at the yellow offset surface. It basically shows where the curve length should be measured. The radius of the yellow surface in bend area is 0.1728. Therefore, the arc length should be equal to 0.1728*0.5*pi. Add them altogether and you will get, 2.79143360527in
The flat pattern measures 2.79143360527559 in.
Please note that this calculation is based on default K-factor (0.44). For Bend Table calculation, please check Help file. There is a good example of Bend Table. Actually, if the unfold length is of primary concern, you might want to use Fold feature, instead of Flange. You can create a face measured in unfolded length. Then start folding.
Let me know if you have any question.
Thanks!

Johnson Shiue
Test Engineer
Autodesk, Inc.
Message 6 of 19
Anonymous
in reply to: dclassen

inside radius is the major factor in bend calculations.
you said part has a 3/16 radius, but part you post is 3/8.
IV calculates properly, given T, IR and K. but metal that thick bend calculations are just a stating point.

my goodness ADSK, lots and lots of sheet metal questions. metal must pay alot of bills.
Message 7 of 19
mount_mordor
in reply to: dclassen

<> lol

I know I got to eat tonight......
Message 8 of 19
Larry Caldwell
in reply to: dclassen

I always thought SM was a big deal ... but ... then again ... guess we got consider who's big deal gets consideration: remember the top-ten thingy; not one SM big deal made it. Maybe that's why SM has been one of the bastard step-children so long. Amaz'n too, sense I can't remember one machine I've done where I didn't use a bunch of it.
~Larry
Message 9 of 19
Anonymous
in reply to: dclassen

the poll was taken from those who use it. not whose who might use it if they had this or that.
I think IV does a pretty good job creating utilitarian SM. And adsk must think so too. so they gave it a rest to work on some wow features. I just don't want them to forget about it completely.
Message 10 of 19
Larry Caldwell
in reply to: dclassen

Yeah ... long as you do just normal SM it works pretty good. Maybe it's a good sign though: they cranked up the back oven and threw in the half-baked weldments to crisp'em up a bit. Pretty cool that.
~Larry
Message 11 of 19
Anonymous
in reply to: dclassen

I'm curious what you would want to see added. I picture machine design only needing sheet metal covers and chutes. Maybe you would want to see slight deformation, like when you got to bolt a cover on surfaces that are not perfectly lined up. But deformation is a large endeavor.
Message 12 of 19
Anonymous
in reply to: dclassen

If I can bend it on a brake press I should be able to model it that is what
I want and still haven't gotten it and have been asking for it since release
1 which didn't have sheet metal we got that in release 2!!

Gary

wrote in message news:4830283@discussion.autodesk.com...
I'm curious what you would want to see added. I picture machine design only
needing sheet metal covers and chutes. Maybe you would want to see slight
deformation, like when you got to bolt a cover on surfaces that are not
perfectly lined up. But deformation is a large endeavor.
Message 13 of 19
Anonymous
in reply to: dclassen

I've made break tooling that deforms metal that i would not expect to model as a feature. What have you been asking for?
Message 14 of 19
Anonymous
in reply to: dclassen

bend a face down 3 degree's each side without cuts in material
wrote in message news:4830502@discussion.autodesk.com...
I've made break tooling that deforms metal that i would not expect to model
as a feature. What have you been asking for?
Message 15 of 19
Larry Caldwell
in reply to: dclassen

I would think deformations would get used a lot doing progressive die work plus I would have the ability to make stuff like the saw blade guard I ended up cobble'n together recently. I also think it would be great for plastic parts when you need funny thin shapes. Have'n to whiddle is pretty much a fact of life if you do stuff other than the basic every-day jobs, but when you do stuff doesn't exist, you run into all kinds of awh-sh..s. Might be nice to be able to soar over some of that maybe. Inventor's a great tool and long as they're come'n with new stuff, it's someth'n I'd like to see.
~Larry
Message 16 of 19
pcunningham1
in reply to: dclassen

If you're talking about what I think you are, we called them 'tension breaks' (to prevent panels from oilcanning), and they were not accounted-for in the flat pattern.
If I were doing that kind of work in IV, I'd fake the lines in with a sketch or something similar.
Paul Cunningham
IV2008
Message 17 of 19
Anonymous
in reply to: dclassen

dosen't sound like cross break, sounds like bending each side, like 1" from edge. And without a little v cut in each corner metal would bunch up. (and probably induce oil canning).
Message 18 of 19
Anonymous
in reply to: dclassen

You bet. there's a whole industry predicting development, metal thinning and rupture. Pretty sure anyone who does deformed part dies will say IV got to work on surface extend and intersection first tho. If your doing one off drawn parts i would think fab shop would beat shape by hand, or cheapo urethane or lam-die, and machine after. No flat necessary.
Message 19 of 19
Larry Caldwell
in reply to: dclassen

I never provide flats to vendors ,,, aside from fact they do their own, 'fraid I'd have'ta pay for it if someth'n whacked. I normally do flats for companies have their own shops and want the flats. The usually want dwg's as well for their water-jet or laser.
~Larry

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