Apparatus for facilitating the rotation of a tool-receiving device

In an apparatus for facilitating a rotation of a tool-receiving device oriented at the free end of a milling spindle carriage, said tool-receiving device being rotatable by means of ring gear means driven by a servomotor about an axis of a milling spindle into predetermined angular positions, said tool-receiving device further being centerable by means of a centering mechanism relative to said milling spindle axis and still further being fixable in the adjusted angular position by means of several hydraulically operable clamping elements which act in axial direction of said milling spindle, the improvement comprising wherein in said milling spindle carriage there is secured an elongated bushing which is concentric with respect to said milling spindle axis, said bushing having at its free end means defining a conical receiving opening, wherein a support sleeve is rotatably supported in said bushing by means of radial and axial bearings, said support sleeve having at its free end a fastening flange for said tool-receiving device, said support sleeve also having above said fastening flange a centering cone conforming in shape to said receiving opening and being received in said receiving opening, wherein a further bearing is provided and interpositioned between said centering cone and said receiving opening for effecting a uniform spacing therebetween, wherein said milling spindle is supported in said support sleeve, and wherein said clamping elements include means for effecting an urging of said bushing and said support sleeve toward each other so that said centering cone is urged against said conical receiving opening.