[TheForge] SOR - to AVOID rotary piercing

[Bruce Freeman]

That link (below) shows the rotary piercing process used in making seamless tubing.  A fascinating process in and of itself.  It seems that if you roll a round billet with sufficient pressure and the correct disposition of forces, you fracture the inside of the billet.  By having a pointed mandrel in the proper place, you make seamless tubing, as described.

I use this as an explanation of the blacksmith's dictum: square to octagonal to round.  I.e., always draw out stock (even round stock) on the squares (though hex works too), then flatten the corners to make it octangonal, then keep flattening corners to make it round again.  If you try to draw out metal round, you may fracture the inside, like in the rotary piercing process.

Bruce
NJ

>>> bamablacksmith at comcast.net 1/1/2006 6:45:07 PM >>>

Cool, it reminds me of watching the folks at the USS Fairfield Plant 
shoving a bore mandrel through 25 feet of steel to make seamless pipe.

Then watching the primary rollers that are powered by 2 ganged 5000 hp 
motors.  That takes the 25' billet and rolls it out to about 75'

http://www.usstubular.com/facilities/splpffal.htm 

absolutely fascinating process.

mike



At 02:36 PM 1/1/2006, you wrote:
>
>To All,
>When I built my hydraulic press I had fantasies about punching conical  holes
>in large blocks for candle holders, etc.  I first used H-13 heat  treated by
>the book and the small end mushroomed on the first press.  The  slow but
>powerful push of the hydraulic works really well but it is hell on  tooling.
>Now for a story...


            Mike Linn
      Artist Blacksmith
          McCalla, AL
        AFC Webmaster
http://afc.abana-chapter.com 

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