Rotatable tooholder having a stationary, through-center coolant feed

Abstract

A rotatable toolholder is provided having a stationary coolant feed system for directing a through-center, non-rotating coolant stream to a coolant conducting bore in a rotating cutting tool. The rotatable toolholder comprises a stationary housing, a driven shaft having an output end rotatably mounted in the housing, and a tool coupling rotatably mounted on an opposite side of the housing for holding and rotating the end of a cutting tool. The coolant system of the toolholder includes a nozzle assembly stationarily mounted within the housing and having a nozzle for directing a non-rotating stream of coolant into the coolant conducting bore of the tool, and a stationary conduit for conducting a coolant flow from a source of pressurized coolant to the nozzle assembly while isolating the coolant flow from the rotating components within the housing. A transmission assembly is provided within the housing for transmitting rotary power from the driven shaft to the tool coupling. The use of a stationary nozzle assembly isolates the flow of coolant from centrifugal forces that the rotating components within the housing would otherwise apply to it, while the isolating function of the coolant supply conduit obviates the need for dynamic fluid seals between the housing and the driven shaft and tool coupling that leak and create frictional drag, and also renders unnecessary micro particle filtration of recirculated coolant.