Re: has anyone tried dynamic damping?

It sounds good but where do we start?
Bob

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Elliot Burke" <elliot@h...> wrote:=

> This is some thoughts about dynamic damping:
> consider a machine as a damped mass and spring system, with a cutting too=

l

> driving it with a periodic force. If mass, stiffness and damping are jus=

t

> so the displacement at the point of the cutting tool will be low.
> Unfortunately this requires a massive system for large forces and low
> frequencies.
> So, either make the tool go really fast (impractical in many cases), or
> extract the vibrational energy from the system with a motor.
> What I am proposing is to put a strain gage(s) between the work and the v=

ise

> or embedded in the work holder or the tool holder, then a few piezo elect=

ric

> motors under the work or close to it. The dynamics of the machine should=

be

> well characterized, a servo can be made to make the system at the frequen=

cy

> and phase of the driving force much stiffer. The piezo motor could push =

on

> a free mass, which would wiggle around a bit, the piezo would pull the
> vibrational energy out. This piezo extracts the energy because the phase=

> between force and displacement is 180° reversed from the normal case.
>
> Since the machine structure is well characterized, knowing the forces on =

it

> would enable the low frequency deflections to be calculated as well. The=

se

> could be used to correct the deflections in software.
>
> Would this be trivial? No. But it might be able to make rigid, lightweig=

ht

> machines. Think of a sherline sized mill with the rigidity of a 2 ton mi=

ll.

> Not only would the quality of cut be better but they should be more quiet=

.

>
> In such a system perhaps the way bearings could be simpler as well.
>
> Machine builders, what do you think?
>
> regard-
> Elliot B.