Patent ID: 6932549

Claim:
Mandrel-holding slide or sleeve pod for a numerical-control machine tool, slidably mounted by means of a carriage on to a beam of the machine tool, in which the position of said slide or sleeve pod is adjustable vertically by means of a lead screw ( 16 ) and nut screw ( 14 ) mechanism, comprising a mandrel-carrier structure ( 10 ) in which there is at least partially housed said lead screw and nut screw mechanism, characterized in that in said mandrel-carrier structure there is mounted an axially slidable plunger-like member ( 26 ) adapted to define first and second chambers ( 40 and 32 ) situated above and below said plunger-like member ( 26 ), respectively, said second chamber ( 32 ) being adapted to be communicatingly connected with a supply source of an oil-pressure fluid at a pre-determined pressure, and said first chamber ( 40 ) being adapted to be communicatingly connected with a supply source of compressed air at a pre-determined pressure, said plunger-like member ( 26 ) being subject to the action of a counter compression spring ( 38 ) calibrated at such a pre-determined upward-directed elastic force as to be able to compensate for the weight of the sleeve pod or slide ( 12 ), said supply source of oil-pressure fluid being activated when the mandrel-holding slide must take the rigidly locked, non-floating normal working condition of the numerical-control machine tool, whereas said supply source of air under pressure is activated when said slide or sleeve pod ( 12 ) must take the floating condition in which a planar surface of a stone material is processed, in which to the mandrel of the machine tool there is mounted a tool-carrying chuck or dish of a type traditionally used in polishing, smoothing and facing machines for stone material.