I need to calculate flatten dimension of equal angle profile. How can I calculate by Solidworks.
To further expand on Mr. Gupta's post:
The flat pattern is dependent on sheet thickness and material.
The material, and to a smaller extent, the thickness, determines the K-factor and the bend radius (which is also dependent on available tooling).
These parameters are needed inputs for SW sheet metal.
If you have your data, you can also calculate it w/o modeling it.
Search "Bend Allowance and Bend Deduction" in SW help for a good image of what's entailed.
For your post, you're a bend deduction.
As you may know:
Compression occurs at the inner radius while the outer radius is in tension.
At some point through the thickness is the transition from compression to tension.
At this point, there's no change in arc length. It's called the neutral plane.
The percentage, starting from the inner radius, through the thickness is your K-factor.
With your thickness and K-factor, you can compute this radius and its arc length.
So your flat width = (2 X 40) + Neutral Arc length - (2 X Outer Radius)
Outer radius = thickness + inner radius (tooling radius).
Model as sheet metal part and get the required flatten shape/dimension. Please note that the flatten dimensions may not be exact.
Thanks for reply
Do you have any idea how we can find neutral arc
Kevin did an excellent job of describing how to manually compute the developed length.
Normally the type and tensile strength of the material results in a different "neutral axis. For instance if it was stainless steel 33% percent of the material resulting in a larger bend deduction would be a good percentage to use. Mild Steel 44% and softer materials (aluminum) 50%. I am assuming you know what the bend radius will be.
In the pic above the "Bend Allowance" is considered the neutral axis.
Most sheet metal shops dial the bend deduction in (for 90°) for extreme accuracy, by cutting a sample piece>measuring the overall then bending it with the required tooling (for whatever radius the will be using). Then add up the OD"s of each flange then subtracting their original overall. This result is the bend deduction.
Neutral arc radius (NAR) = inner radius + (K-factor X thickness)
The neutral arc length is the bent proportion of the circumference of a circle at NAR, in your case, 90/360.
The K factors we use are different from the values Mr. Bacon posted and there's the issue.
You probably won't find any firm answers when asking about K factors.
It's a combination of art and science.
Fab shops don't tend to share these numbers.
When we get client SW files, we mod them to our data, if they're different, for the fab shop.
More brittle materials generally have lower K's, like SST.
Mr. Bacon specified K=.44 for AL.
We use a higher value (see, I'm not telling) but that's for the softer 5052 series. 6061 is stiffer, so we'll lower the K and bump up the inner radius to prevent cracking.
As a suggestion, model your part and enter the K factors suggested here.
Do one at a time and record the differences in flat width to learn for yourself the affect K has (just a change in the neutral arc length).
Also, start with an inner radius equal to the thickness. If the material is stiffer/more brittle (or thicker than 3 gauge), start with a radius of 150% of the thickness.
Good luck & cheers,
Actually I indicated 50% for Alum Kevin. I rarely use k-factor and when I do it is to for compound bends and rolled bends (over 170°). If I need a sharp bend on 6061 I use -0 then heat treat to T6 or whatever is required. Lot's of aerospace and military require that.
Like you said the k-factors that I indicated may change from shop to shop if they use k-factor which would be unusual. The numbers I gave came from another post on this forum from a guy who's judgement I trust.
Oops on the 50%!!
We only use k-factor so we can get the flat pattern to the laser at the "right" size, by which I mean what the fab shop needs for how they work their magic.
We worked out a few K's for various materials, etc. so we can do a quick edit on the client's SW and get the job into production with minimal overhead.
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