topic Re: Bend deduction table in Inventor Forum

Bend deduction table

Charlies_3D_T — Wed, 13 Feb 2019 09:27:32 GMT

Hello,

I have a problem with the bend deduction and k factor.

I got a bend deduction table from trumpf and i want to add this to my unfold rules. But i can only insert a k factor table. How can i add a bend deduction table? That tells for what thickness and what angle the deduction will be?

Hope someon has an idea?

Thank you!

Charlie

Re: Bend deduction table

swalton — Wed, 13 Feb 2019 15:05:14 GMT

I haven't used bend tables, but I think the online help should get you started.

http://help.autodesk.com/view/INVNTOR/2019/ENU/?guid=GUID-27FD9757-5B40-4528-B361-D9BDFDB2EA4D

Post back here if you have any questions about how these work.

Re: Bend deduction table

johnsonshiue — Wed, 13 Feb 2019 19:57:06 GMT

Hi! It is not that hard. You do need to set up once. But, after that, you can reuse the rule. Inventor actually ships with two example Bend Tables (C:\Users\Public\Documents\Autodesk\Inventor 20xx\Design Data\Bend Tables). You can start a new sheet metal part.

1) Go to Manage -> Styles Editor -> Sheet Metal Unfold Rules -> create a new rule -> set it to Bend Table type.

2) Open the example bend table in Excel or any table editor. You will see a bunch of bend tables. The table is thickness specific. You need to specify the thickness value. The copy the table and paste it to the rule table. Make sure you delete the line ";opening angle ----."

3) Repeat the process for other thickness values.

Many thanks!

Re: Bend deduction table

huntervin17 — Sat, 04 Feb 2023 17:04:54 GMT

hi,

can you send me the updated spreadsheet from trumpf you received?

thank you in advance

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 19:34:50 GMT

Hello,

Could you explain me how correction works, becouse it seems wrong.

I tried table from you explanation. Just make 49x50mm and 45° and when I measure, it is always wrong.

I used table from insatalation: C:\Users\Public\Documents\Autodesk\Inventor 2024\Design Data\Bend Tables

Where correction for 45° is - 0,439021

From formula there: L=A+B-x it should be 98,560 for radius 0,5 mm

But is wrong after unfold: - 99,380 mm --- Totally wrong!!!

It seems that table do not work.!

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 19:39:52 GMT

If it would be + it is anyway wrong, or chande angle to A or B. Still wrong.

Re: Bend deduction table

Frederick_Law — Fri, 01 Dec 2023 19:56:30 GMT

Leg measurement is to the sharp point. ie no radius.

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 20:05:23 GMT

I do not understand your advice. I do not measure any radisu, I though that it will be that correction after unfold.

Re: Bend deduction table

Frederick_Law — Fri, 01 Dec 2023 20:12:48 GMT

You are mixing up two different method:

https://www.adhmt.com/k-factor-bend-allowance-and-bend-deduction/

L=A+B-X deduction, subtraction

L=A+B+X Allowance, addition

Re: Bend deduction table

kacper.suchomski — Fri, 01 Dec 2023 20:17:03 GMT

@david.karoly I don't understand what you mean at all.

The bending table is a manual tool.

Both the bend table and the K-factor are elements of the same equation from two different sides. The K factor multiplies the radii and the table calculates the difference in values. The end result is the same - finding the nominal length for the neutral axis (plane).

The main difference (besides the mathematical formula) is the workflow of these tools.

In the case of the K coefficient, we are dealing with multiplication, so once the parameter is defined, it is used to calculate all value variants.

In the case of a table it is similar - but you have to prepare a whole series of samples, because... there is no multiplication; is direct correction. Therefore, you should prepare as many samples (different variants) as you can, and then complete the table. The remaining (intermediate) positions will be calculated interpolationally.

This is exactly what the bend table workflow looks like:

You bend 10 details (same radius, different angle)
You count the differences
You fill in the cells
You work and design - You use the table even with undefined values, counting on the correct accuracy of the calculated interpolations.
And so for each radius xD.

This is the only way, because the bending table is a manual tool.

You have to work through it. Prepare samples, measure, calculate and complete the table. And so for each thickness, radius, angle and technology (k-factor). Then it will work your way.

You cannot expect the table to be correct right away - it is not adapted to your technology and material (i.e. it is calculated for a different K-factor).
This is your task - you must complete the table; then it will be correct. And you will be able to use it.

Expecting top-down bending table compliance shows a misunderstanding of this tool and process.

Re: Bend deduction table

Frederick_Law — Fri, 01 Dec 2023 20:30:57 GMT

How did you get number for the table?

0.092588?

What did you used to measure to 6 decimals?

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 20:50:30 GMT

That table is from Instalation Inventor: C:\Users\Public\Documents\Autodesk\Inventor 2024\Design Data\Bend Tables

There is table for t=0,5 mm and few radius and angles.

That I tried, I want to see how it will work but I see I do not understant anyway. Becouse if I triend to measure outside as you told me.

Like this should I measure?

A+B -x =...

it is till do not work 😄

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 20:53:58 GMT

Hi,

Thanks for your answer, but I have that same table from Trumpf with radius, angles and thickness and how much will it be cut, but i do not know how to put it inside inventor to have correct results. But If I tried there anything, after unfold in inventor, it is wrong. that is my problem.

Re: Bend deduction table

kacper.suchomski — Fri, 01 Dec 2023 20:55:07 GMT

And in the sheet metal settings, did you choose to use the bending table or the K factor? Because this is probably the answer to your worries.

Re: Bend deduction table

kacper.suchomski — Fri, 01 Dec 2023 20:58:29 GMT

And here you will find instructions on how to edit the table.

https://help.autodesk.com/view/INVNTOR/2024/ENU/?guid=GUID-48045F68-14D4-4861-9200-50EE59913FD4

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 20:58:40 GMT

Of course. If you mean here.

I tried put into table very easy values like 0,5 mm and then check it and it is anyway wrong. Try it yourself, becouse I think it is not work correctly.

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 21:11:54 GMT

You can try very simple example:

i make table for t=0,5 mm and raidus 30° it will be x=0,5

Then sheet metal 50x49 mm

Where I see result 99,036 mm what makes no sense.

Re: Bend deduction table

Frederick_Law — Fri, 01 Dec 2023 21:13:36 GMT

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 21:20:18 GMT

I see it must be to intersection point. Thank you.👍

Re: Bend deduction table

david.karoly — Fri, 01 Dec 2023 21:21:17 GMT

Thank you.