Forming a metal helix

[ccaissie]

Is anyone familar with a method of twisting or forming a helix from a strip or plate of stainless steel?

In this case I am using 304, about .12" thick and 1.4" wide, and need the "pitch" to be about 4.5" per complete turn.

We have large lathes, so power and control is not an issue in twisting, but the stretching at the edge of the helix is where the problem is.

CSC,
UET Mixers

 

[BillPSU]

How big of a diameter will this helix be? Hopefully rather large (3-4" diameter).

Make a mandrel tool with a female helix in the tool. Use a CNC machining center with a rotary table and mill the helix in the mandrel. Heat the material to a temperature where it forms per your wishes. You will probably have to heat the mandrel as well to avoid cooling the part during forming. Stretch for the strip into the mandrel. Remove the tailstock from the mandrel and unscrew the helix from the tool.

 

[ornerynorsk]

Auger flighting is manufactured using a spring winding process. It is cold formed, don't waste your time heating. The tooling could be improvised, but probably not worth it unless this is a very important job or large volume.

 

[griffengm]

ccaissie,
Your problem depends on the elongation of the material. You need a strip about 5.5 inches long to form the i.d.. It needs to stretch to about 14 inches for the o.d.. You can calculate the true length according to the pitch angle but I believe you are asking for a lot more stretch than available.

Griffy