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Sheet Metal Drawings Dimension Problem

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Message 1 of 8
Nameless337
8358 Views, 7 Replies

Sheet Metal Drawings Dimension Problem

I'm consulting for a company that works a lot with sheet metal.  When the sheet metal model is unfolded into a flat pattern, Inventor uses the bend radius and stretch information to locate the brake lines.  The problem is the factory guys who run the brake are set up to accurately and easily hit the flange height for all the materials they use, so that' s the dimension they want to have.

 

What I'm looking for is a way to place the flat pattern in a drawing but have the brake line dimensions linked to the flange height of the folded model.  Currently I have to go through every drawing and manually override the brake line dimensions, which is extremely tedious, especially since I'd have to do it all over again if the folded model every changes.

 

7 REPLIES 7
Message 2 of 8
mcgyvr
in reply to: Nameless337

So if the flange is 1" you want the dimension from the end of the flange to the bend line to be 1"?

When programming the press brake do they enter 1" to bend a 1" flange?



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Inventor 2023 - Dell Precision 5570

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Message 3 of 8

Hi Nameless337,

 

Can you post a screen shot and/or simple example file(s) of what you're trying to accomplish?

 

I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com


Message 4 of 8
Nameless337
in reply to: mcgyvr

Yes that's the idea.  I was surprised too but I from what I understand that's the case.  If they want a 1" flange they enter 1".  They have some correction factors for a couple of the thicker gauges but for the most part that's how it works.  I'm not comletely sure why it works that way. We've determined from testing that when they brake a part all of the stretch generated goes into the base with no stretch going into the flange.  That's part of what's going on but I'm still not sure why their flanges are not off by the bend radius and the material thickness.  Regardless that's the easiest way for them to do it so those are the dimensions I give them.

 

I've posted two screenshots.  What I want to do is take the dimensions measured in the model (outside face to outside face) and have that be the dimensions referenced by the selected dimension annotation in the drawing.

 

The brake lines will be wrong in the flat pattern, but as long as the blank size is correctly accounting for stretch it shouldn't matter where inventor thinks the brake lines are. 

Message 5 of 8
mcgyvr
in reply to: Nameless337


@Nameless337 wrote:

Yes that's the idea.  I was surprised too but I from what I understand that's the case.  If they want a 1" flange they enter 1".  They have some correction factors for a couple of the thicker gauges but for the most part that's how it works.  I'm not comletely sure why it works that way. We've determined from testing that when they brake a part all of the stretch generated goes into the base with no stretch going into the flange.  That's part of what's going on but I'm still not sure why their flanges are not off by the bend radius and the material thickness.  Regardless that's the easiest way for them to do it so those are the dimensions I give them.

 

I've posted two screenshots.  What I want to do is take the dimensions measured in the model (outside face to outside face) and have that be the dimensions referenced by the selected dimension annotation in the drawing.

 

The brake lines will be wrong in the flat pattern, but as long as the blank size is correctly accounting for stretch it shouldn't matter where inventor thinks the brake lines are. 


First..entering 1" to get a 1" flange simply means they actually took the time to setup the press brake controller properly.. (Most companies don't)

 

Second...Your testing/theory about stretching in the base is incorrect. Refer back to #1..Its all about proper programming of the press brake controller.

 

Third..My suggestion is to simply NOT dimension to the bend lines on the flat pattern. Include them in the formed dimensional drawing only. Problem solved.The flat pattern should really only be used to program the punch/turret press not the press brakes.

 

Its not that the brake line dimensions are wrong (If your K factor is right and I'd guess it is because your blank sizes are correct then those lines are correct too).. Its that your press brakes were setup from the start to remove the need to have the press brake operator do any math or follow a lookup/correction table,etc...  So your dimensioning bend lines in the flat pattern is overriding the work done by the genius press brake controller programmer.

 



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Inventor 2023 - Dell Precision 5570

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Message 6 of 8
Nameless337
in reply to: mcgyvr

So you're saying to just give the brake guys drawings of the 3D folded model instead of a flat pattern with bend lines?

Message 7 of 8
mcgyvr
in reply to: Nameless337


@Nameless337 wrote:

So you're saying to just give the brake guys drawings of the 3D folded model instead of a flat pattern with bend lines?


It depends on how they program the punch press (not press brake).. I'd suspect they might use the flat pattern dimensions/drawing for punch press programming. But yes for a shop that has their press brakes setup properly like you do I would give them a "as formed" dimensional drawing for the forming cell. Think of all the time/manual labor I just saved you.. 🙂

 

We only do prototype sheet metal in house but I do the same.. I give a flat pattern drawing with ordinate dimensions so the CNC guy can program the part then a formed drawing for the press brake operation.



-------------------------------------------------------------------------------------------
Inventor 2023 - Dell Precision 5570

Did you find this reply helpful ? If so please use the Accept Solution button below.
Maybe buy me a beer through Venmo @mcgyvr1269
Message 8 of 8
Nameless337
in reply to: mcgyvr

Good enough for me.  Thanks for the help.

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