Developed Lengths Formula

[patdesign]

Looking for a formula to calculate developed length for steel sheet and plastic sheet......

 

[dooron]

I have seen around some basic computer programs, in the sheet metal magazines, that calculate the developed shape for all pipe/pipe, box,box, joints.

 

[reamer]

Have you found your answer? If not please reply and we can make arrangements to send you a setback chart.

 

[okeng]

If you're still looking for sheetmetal bending info, I've got a nice little excel spreadsheet calculator that will figure "bend allowance". It will give you the length (along the neutral axis) of the material in the bend for any radius and thickness. I use it all the time and would be happy to share it.

Jess Davis
Davis Precision Design

 

[sancat]

There are two sceneries
The most common, you know the weight of the roll. It is straightforward, since you most possibly know the width, and weight per area.

The special case, you know the length, but don’t know the final diameter of your roll, or you know the diameter but would like to know the length.

For this second case, for the

1st turn, you will have r1=r0 and S1= 2 x pi x r0
2nd turn r2=r0+e and S2 = 2 x pi x (r0+e)
i turn ri=r0+(i-1) Si = 2 x pi x (r0+(i-1) x e)
n turn rn=r0+(n-1)= rfinal Sn= 2 x pi x (r0+(i-1) x e)

Where r0 is the initial radius (core radius) or core diameter/ 2
e is the thickness of the sheet
And n is the total turns.
If you don’t know n you can divide (rfinal-r0)/e

Adding the S between I=1 and N
Stot = n x (2 x pi x r0) + e x 2 x pi x (Sum (i=1 to n) (i-1))
Stot = n x (2 x pi x r0) + e x 2 x pi x (n-1)/2
Stot = n x (2 x pi x r0) + e x 2 x pi x (n-1)/2
Stot = n x 2 x pi x (r0 + e (n-1)/2))

The formula is easily seen as a stack of n sheets, with the shorter with a length of 2 x pi x r0 and the longest with a length of s x pi x r final. The length would be the mean length multiplied by the amount of sheets.

sancat

 

[reamer]

Send me an e-mail at keene.machine@verizon.net. We can get you the chart you need but going the eng tips forum is a pain in the a---! I'll make a .pdf of it for you. I don't think this chart will work for plastics as plastic don't tend to bend very well. However with the proper technique, one may thermal-form it.
Hal