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Die drawn tube for rifling

partsproduction

Titanium
Joined
Aug 22, 2011
Location
Oregon coast
I had an idea for drawing a steel tube with a solid forming mandrel inside through a wire drawing type die. The mandrel would have the rifling form engraved on it's surface and just slip inside the tube, and the end of the tube would be squeezed down in diameter to enter a round drawing die, then drawn through it hydraulically.

In the process I imagine the length of the blank would increase as the OD decreased, but material springback should allow withdrawal of the mandrel when done. The mandrel would have to be hardened to some degree I suppose.
I also imagine there would need to be considerable experimentation to get the finished bore diameter right because the springback might be variable.
Such a rifled tube would be suitable for air rifles or even liners for smokeless powder rifles and pistols.
The main advantage over button rifling being the saving of material, as to get a thin wall tube to "take" the rifling by the button you'd either have to press the tube inside a larger OD containment vessel or start with a larger diameter and turn it down later, as otherwise the tube will stretch at the areas of least resistance and the wall expand beyond it's elastic limits, with no rifling being formed.

I describe all of the above to ask this question, has this been done before? It has elements of hammer forging without the hammers, the OD burnished die providing the inward forming force.
It might also have other uses to form a desired finish inside thin wall tubing at low cost.
Also, I know there aren't many new ideas out there, so I don't imagine this is one either.
 
FWIW, Redman's 22 cal liners are only 5/16" OD and are button rifled. You can see a faint trace of the grooves on the outside of the liner. I do not know if they are temporarily encased in a larger tube before being rifled or perhaps turned down from larger dia. stock, but I doubt it. The outside of the liner appears to be the mill finish from the tube manufacture's dies.
Redman's Rifling & Reboring: Available liners and prices

RWO
 
Every form of swaged or drawn rifled liner has been in production at some time for over 100 years.I noticed a recent Turkish patent for large dia rifling rolled in by external rollers with an internal former.
 
a recent Turkish patent for large dia rifling rolled in by external rollers with an internal former.

Interesting, dispenses with the huge expense of hammer rifling equipment. I would imagine the tube would start out smaller than it ended up.
 








 
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