[TheForge] Re: Rebound and Work

[Steve Smith]

Thanks Mike.

Steve

Mike Spencer wrote:

>>How about this one--does a dead blow hammer do any good in forging? My 
>>bet is no, you just make the shot in the head warmer...
> 
> 
> I don't know what a dead blow hammer is but I infer that it's a hollow
> steel hammer head almost but not quite filled with lead shot. (How'm I
> doing? :-)
> 
> I'd agree.  Ignoring the fine details of the impact event, the fact
> that there is rebound means that a force is exerted through a distance
> on the hammer head -- presumably because the hammer-anvil-workpiece
> combo acts as a spring or something similar -- thereby accerating the
> hammer head in the up direction.
> 
> Using a shot-filled hammer wouldn't affect that mechanism so if the
> shot-filled hammer fails to rebound where an ordinary one does, then
> yes, I'd assume it was just heating the shot.
> 
> 
>>Change in kinetic energy (scalar) is what counts and is what is
>>converted to heat or smush.
> 
> 
> Yeah.  And smush is eventually converted to heat, too, unless perhaps
> under (weird?) circumstances where you actually cause some of the
> inter-atomic bonds to end up in a higher energy state than before the
> blow was struck.  Normally, you's expect the bonds to stay the same
> (on average) or go to a lower state as in stress-relieving a cooled
> weld by hammering.
> 
> 
> - Mike
>