[TheForge] Tungsten

[Hochewa at aol.com]

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...
When I was a co-op with Bethlehem Steel in the summer of '68, The  battleship 
New Jersey was off the coast of Vietnam consuming what was left of  the 16" 
projectiles made for the Korean War.  Bethlehem was one of the  primary 
contractors for such things and they had to tool back up.  In the  years between 
conflicts they apparently misplaced some of the  procedures for a while.  My boss 
and I were called in to see  what if we could resurect the process for making 
the dies for the 16"  projectiles as the ones left over from Korea were 
wearing out.  The first  task was to go over to the forge to see what was going on.  
 The  press was something like a 250 ton  "H" frame being fed by robotic  
handler and a rotary hearth furnace holding 30 preforms.  The cycle began  after 
the last forging was cleared from the die.   The robot pulled  something like 
a 14x14x24" billet out of the furnace at a nice orange  heat and dropped it on 
end into the die.  The first tool to enter the  die was a 16" round that 
pressed the billet to fill the bottom of the die.   The next tool was a 6" 
round-nosed punch that back extruded the billet and  set the ID of the projectile.  
The very back of the projectile now just  stuck out of the die.  The forging 
was then ejected from the die and the  robot put it on the cooling rack and 
grabbed another billet.  The entire  cycle took 90 seconds.  The 16" punch lasted 
forever, the dies lasted about  a 1000 cycles before they heat checked so 
badly the had to be re-machined and  the 6" punch was changed about every 100 
cycles.  The rough forgings were  normalized, rough turned  and heat treated 
before being sent to the arsenal  for finish machining and charging with the 
explosive.  The rough forging  had the classic bullet shape and except for being 16" 
in diameter and 4 feet  long looked pretty normal.
Anyway, beating on a punch to make a hole has the advantage that each hit  
wiggles the tool a little bit which helps it not stick to the work and in  
reality helps keep it cool by minimizing the contact area.  Also when I  lived in 
Bangor, ME, it was right down the road from Peavy Tool.  When they  punched the 
hole in an axe head or such , it only took a few seconds to push 3  or 4 ".
FYI,
 
Hochewa
 
 
 
 
In a message dated 1/1/2006 10:25:14 A.M. Eastern Standard Time,  
sos at alum.mit.edu writes:

Thanks  for the details, Hochewa. It does seem like difficult stuff for  
blacksmiths to work with. From what you're saying, it wouldn't work  well.

The problem we're really aiming at with the tungsten is slitting  and 
drifting large pieces in a hydraulic forging press. The tools we've  
tried have a marked tendency to weld in the hole. Pretty ideal  
conditions for welding it seems to me--steady pressure, scraping to  
clean off any impurities (like anti-seize). What alloy would be least  
likely to weld, and will it really be much improvement over other  alloys?

Steve