Problem with bend Table

[anatolyisg2014]

Hi for all!

I have a little problem with bend table. We have a few bend tables for CNC-machines. For example:

Aluminum sheet 3 mm. Bend Radius - 3 mm. Formula L=A+B-factor:

Angle 70 – factor 3.316;

Angle 80 – factor 4.016;

Angle 90 – factor 4.858;

Angle 100 – factor 3.914;

Angle 110 – factor 3.142…

I tried many variants of setup the bend. For Angle to 90° - all OK.

 L=20+20-4.016=35.984

L=20+20-4.858=35.142

But! For Angle more 90° is false. What I do wrong and, how can I fix it?

L=20+20-3.914=36.086

Please, give some tips.

Thanks.

[johnsonshiue]

Hi! I took a quick look at the part. I think I know where the confusion is. For Bend Table method, the unfold length is computed by A + B - x, where A and B are the length on each side measured up to the bend zone. x is the correction value from the table based on the bend angle, bend radius ,and the thickness.

When the Bend Angle is less than 90 deg, A and B are measured from the each flange end up to where the two flanges intersect.

But, when Bend Angle is more than 90 deg, A and B are measured differently. It is from each flange end to the tangent plane to the bend zone.

For Bend Angle = 100 deg, 18.85 + 18.85 - 3.914 = 33.786

Many thanks!

[anatolyisg2014]

Hi. Thank you!
I am understand this situation.
At now, I would be want to know, what i can to do? How I can using this table?
Maybe, Inventor have another method, equal this table?

[johnsonshiue · Accepted solution]

Hi! This could be a bit counter-intuitive but here is what you need to do to see the unfolded length you are looking for. When the bend angle is larger than 90 deg, the Flange Height Datum and the Bend Position options need to be changed to the one on the far right in the dialog.

This is because the definition of A and the B isn't the same from 0 deg all the way to 180 deg. In your case, you want A and B to stay at 20 mm. If you do the measurement on the model at different angles, they are not 20 mm each.

Many thanks!

[anatolyisg2014]

Hi! I not sure, how it is work, but You right! Thank you very much!!!

When angle is more 90 degree, just enough to change two button (on the picture).

This is working! 😁

Maybe, in new version Inventor, someone add special function for this solution...

Angle <= 90

Angle > 90