Thread rolling fittings - GIF

[Altair]

Thread rolling fittings.




Previously:

Thread rolling cylindrical dies - GIF
Thread rolling machine - GIF
Machining a multi-start thread - video
Threading a large shaft - GIF
Auto-retracting thread cutter - video

[Toolmaker51]

Compared to previous GIF, this shows process well, better lighting and color of material help too.
Not much oil is running, tells me these are pressure cast (or forged) aluminum fittings, not likely stainless steel.
Such raw parts are often chucked in a two jaw with formed cavities for sides and corner. One spigot is drilled to depth, thread OD turned, neck relief, seat of flare and the area past it to the thread a bit under minor diameter. Then re-chucked for other end and part is complete, less thread rolling, then anodizing. Those last two insure far longer service life than cut threads ever could, with anodizing to limit galling.

[Saltfever]

There are at least 5 revolutions of the fitting, however I don't see any axial movement of either the dies or the part. How can a thread revolve and not move axially?

[Toolmaker51]

Tried googling better description than what I suggested on the other threading GIF, but sure it's connected to counter-rotation of the rolling dies. As in the 'travel' is performed by helix of the thread forms.

[tooly]

Tried googling better description than what I suggested on the other threading GIF, but sure it's connected to counter-rotation of the rolling dies. As in the 'travel' is performed by helix of the thread forms.

I would like a better explanation if possible, I can not get my brain around this.

[Toolmaker51]

I would like a better explanation if possible, I can not get my brain around this.

It's magic?
Sorry. I'll re-word search terms, returns are more advertising than information.