Auger screw to sheet?

marek_zbikowski

Hi. How can I transform auger screw spiral (1 turn) into a flat sheet metal surface?
I've tried the available options, but I can't seem to accomplish it. Here is the link to the project I want to replicate on a piece of sheet metal and then bend it:

https://cad.onshape.com/documents/6071498443334e0865974cd6/w/2f1bfcb60ead8585c9d50ca0/e/5bb8f805a4cd371d882556e8

Paul_15

I used to have to deal with these in SolidWorks. They aren't sheet metal parts and the way they are made would affect the undeformed shape. Since they aren't sheet metal and have multiple ways to make them, OnShape or any other CAD likely wouldn't be able to un-form them. In SW there was a package that might do this, but that was long ago.

If you were familiar with the manufacturing process you could simply draw the unformed shape which is a circle with a hole and a gap and add some allowance for stretch.

marek_zbikowski

Exacly problem is in sizes formed or deformed.
This is for my personal hobby project that will be done in future, and i want bend it also myself. Draw flat will be usefull to cut sheet before bending.
I saw YT videos that someone do it in SW but this software is some problematic to me, i make few draws in onshape and im still looking way how to do that here. If sheet option will not work, maybe it is any other way to do that? This looks like big challenge

rick_randall

Screw conveyor flighting is made by rolling the outside edge of a piece of flat bar through tapered rollers, which thins and stretches that edge. (They are not cut from flat sheet). It's the stretching that turns it into a spiral. Like the guys above have said - sheet metal does not support this stretching behavior in the flat pattern. 

You can accurately model the finished flighting as a solid, by sweeping a trapezoid profile along a helix (thinner section at the outer edge) 

  Bad news is, it will not develop a flat pattern in cad - And this is also the reason why you can't make curved flanges that work with flat patterns in sheet-metal (does not support stretching or shrinking,and will fail)  

Forming complex shapes in sheetmetal parts is made by either shrinking or stretching - and it is truly a fascinating subject. I would recommend that you research it fully.

Good luck

barry_chisholm

Not sure where everyone gets the idea that this can't be done. Screw flights are made from cut outs of sheet metal. Some are also rolled flat bar. Solid works have an option on how to produce the flat pattern from the helical piece. I have been trying to do this exact same thing in Onshape and struggled.

https://youtu.be/IKuPjYmufAo?si=gKmgqX9F7gVVDA6-

Derek_Van_Allen_BD

Lofted sheet metal still isn't currently supported by the Onshape sheet metal kernel. Surface Flatten is the closest thing at the moment until they unleash the lofts.