I have drawn a cylinder, with inside diameter 1028mm, wall thickness 5mm. We usually have calculated unfolded part length like this: outside dim. 1038mm - 5mm (wall thickness) = 1032 x 3,14 = 3240mm. Now when i unfold in inventor I get for the length 3215,35mm. It is quite far from the result we usually would have received.
Unfolded part will be rolled to cylinder. What parameters should be overlooked when making unfolded parts for plate rolling?
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Check your sheet metal setting. I get 3243.380 mm unrolled.
You can use a bit of a trick to set up the Contour Roll tool to allow you to specify the Developed Length for rolled cylinders. In order to specify the developed length you need to have a small flange, otherwise you will not get the Unroll Method options.
First set up your sketch with an extra little flange:
Then you can set the Unroll Method to Developed Length:
Then create a work plane to define the actual height of the cylinder and use the Split tool to cut the extra flange off.
Attached is a sample file that you can look at as well.
I hope this helps.
Best of luck to you in all of your Inventor pursuits,
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You should pay attention to the unfold method you are using on your design.
You have basically three methods: Kfactor, Bend Table, and Unfold Equation.
At first try to adjust the Kfactor, until you get the desire value (that I assume is the one you get in real fabrication) and then create a template.
You should be very carefull because when you are bending and folding sheet metal you have some factors involved like the thickness, material and the bending machine.
As the sheet development is not "rectangular" the flat pattern will be different to a stock calculation for development.
(150mm off-set centers)
A stock rolled development would be (as previously mentioned) 3243.4mm
or 4 x 810.845 = 3243.38mm (excel spread sheet - see captures)
Using inventors k factor of 0.44 you would expect a development length of 3216.9mm
hope this helps
1038mm - 5mm (wall thickness) = 1032 x 3,14 = 3240mm.
You are calculating the neutral circle in the bent part without allowance for bend stretching in the flat.
As shown in the formula posted by Mark
When you bend material it stretches on the outside of the bend and compresses on the inside of the bend.
The neutral plane (no stretching, no bending) is often (usually? allways?) not in the center of the material thickness.
The Bend Allowance is a function of the Material, Thickness, Bend Radius and the Bend Angle (and perhaps direction of grain in the material).
You have about 70 bends (I lost count) that are stretching the material.
Oops, I didn't need to count - Inventor Bent Table tells me 72 bends. That is a lot of bends to allow for stretching.
You need to find an appropriate technique for calculating this stretching (k-factor, bend allowance table...).
See your Machinery's Handbook section on Bend Allowance.
Unfortunately machine is ancient and documentation is not available anymore. We have successfully managed to use so far formula: outside diameter - thickness of the material x 3,14, for the materials we most commonly use. I will test other options.
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