Screw Conveyor Flight Flat Pattern 1

[rocksolid]

Is there a simple formual for figuring out a basic
flat pattern for a helical screw flight segment?
Example: 9" diameter screw x 4" core x 1/4" thick flight, 18" pitch, 90 degree segment.
I dont mind being just close on the flat pattern. I can
afford to trial a couple of pieces prior to making the
final part. I just need a good starting point "formula" to work from
Thank-you.

 

[MikeHalloran]

The last message in this argument looks about right:

http://www.engineersedge.com/

http://wwwboard/posts/2123.html

Mike Halloran
Pembroke Pines, FL, USA

 

[PeterCharles]

Follow this thread ---

http://www.mcadforums.com/forums/vi...tdays=0&postorder=asc&highlight=screw&start=0

 

[GJB10X]

If you want to accurately develop a flat pattern for a helical screw flight then go to the Advanced Spiral Technology Web site

http://www.advspiraltech.com

There you can use the trial version of their Flight Blank program.

Not only can you do standard helix patterns but also screw flights with various features such as internal and/or external tapers, Ribbon flights with integral legs, Notched flights etc.

The program is extremely accurate but relies on the fact that your cutting methods are accurate and that you do not deform the metal in your forming process.

Good luck

 

[PatCouture]

Hi Mike

I had forgotten about this thread on the engineers edge forum but now that I read it I remember trying this method with no success. I haven't been able to know what went wrong thought but since you are causing the material to deform, the dimensions of the flat pattern becomes too big once you have extended the screw. So theorically it is a case of geometry but in practice it's different.

So feel free to use the formula but I'm sure that it will not give you the same dimension as the software from Advanced Spiral Technology would.

Just my 2 cents

Patrick

 

[MikeHalloran]

When you make a cone, you cut out an arc and pass it through a slip roll. The slip roll bends it.

I'm imagining that to make a screw flight, you need a similar blank, but the tool has to twist it, not bend it. I don't think a generic tin shop has a tool that can do that in a controlled way.



Mike Halloran
Pembroke Pines, FL, USA

 

[berkshire]

As someone who has made screw flights in the past.
For the oddball flights where you did not have dedicated tooling, the forming method was to take a 1" square bar with a clamping device in the middle of it, this bar was about 3'-0" long. The flat pattern had one end clamped in a vice, the bar was attached to the other end.
The screw flight was heated cherry red with a large rosebud torch with the inner portion of the flight hotter than the outer. then two people would smartly pull on the bar, stretching the flight to the desired pitch. The area where the vice and the bar clamped the flight would kink and would be trimmed out. This method will work for up to a 9" OD flight made of 1/8" material. Any bigger than this, you need to look for some bigger people.
B.E.

 

[berkshire]

One thing I forgot to mention, the vice was mounted about 30" off the floor to the leg of a work bench which was bolted to the floor so that the jaws of the vice were horizontal. the two guys pulled straight up.
B.E.