[TheForge] Power hammer Vs air hammer

[John Husvar]

On 5/23/06 7:34 PM, "Demon Buddha" <osan at netlabs.net> wrote:

> 
> 
> Rich Maynard wrote:
>> My suspicion is that with a compressible fluid you would not be able to rely
>> on positioning like that unless you incorporated some kind of feedback.
> 
> Well, I'm not necessarily looking for precisely that sort of precision,
> but only something in the ballpark.  Also, compressibility for a given
> mass (ram) is largely dependent on the volume of air.  As the volume
> increases, the ram becomes "stiffer" in its motion.

How about just making the input air and exhaust air go through proportional
valving?

This could be done using a foot pedal valve that controlled both sides
equally. Wide open would allow free exhaust and input, partial would allow
the exhaust air to resist the movement of the ram. Since the input air
pressure is higher than the exhaust pressure it could overcome it and drive
the ram down, but slowly or fast as you wished.

IIRC that's how the huge air hammer I lost 10 bucks on at Corey Forge in
Corey, PA, worked. The operator controlled both the input and exhaust air
from the podium. Hammer was at least 15 feet tall and had a freakin' HUGE
hammer block. With changeable dies.

I took a bet against the operator being able to control the thing well
enough to drop the hammer on an egg and not break the egg. He did it.

He'd won quite a few after-work 12-packs that way and he won another one
from me. 

That could control hammer position by closing the exhaust valve stopping its
fall.  With the ram thus stopped, you could restart it from wherever. That
operator could, which improved his control -- and his financial condition.:)