Thread rolling machine - GIF

[Jon]

Thread rolling machine. Making a leadscrew? Large GIF:




Previously:

Bolt threading GIF

[Jon]

[Ralphxyz]

So why doesn't the screw screw in as it is being formed?

Ralph

[IAMSatisfied]

"So why doesn't the screw screw in while it's being formed?"

Because it's turning with the dies... if you grabbed it with some pliers to stop its rotation, then it would get pulled inward.

I'd really like to see the operation for forming the Allen head of that bolt.

[Toolmaker51]

Thread rolling occurs same as knurling, where pressure impresses pattern of the 'die'.
Compared to single point threading, because material isn't removed, the grain structure follows the thread profile. Very accurate, smooth, strong and at less expense than cutting.
Socket heads are made in different ways; depends on volume produced. Most are upset in a header and knurled, a mandrel punches the hex from an undersize recess. That by the way also preserves metallic grain as thread rolling does.
Larger hex can be rotary broached, often chips remain adhered in the bottom corners.

[JoeVanGeaux]

So why doesn't the screw screw in as it is being formed?

Ralph

I thought the same thing, but when I looked closer at the relative rotations between the screw(bolt) and the dies, it looks like the bolt is unscrewing itself backwards at the same rate that the dies appear to be drawing it forward. (Basically, a different way of saying the same thing as what IAMSatisfied, said.)