Patent ID: 6315507
Filing Date: 2001-11-13
Classification: B23Q,F16H,Y10T

Abstract:
A drilling or milling head comprising:a housing;a rotatable collet chuck which is opened by axial displacement with respect to a clamping sleeve mounted within said housing;a drive shaft operatively connected to a motor for rotatably driving the collet chuck;a transmission interposed between the motor and said drive shaft for stepping up or stepping down the rotational speed of said collet chuck relative to said motor; anda quick change mechanism for opening said collet chuck, said quick change mechanism including a friction clutch through which force required to axially displace and open said collet chuck is transferred to said collet chuck;wherein said transmission comprises outer and inner bearing rings disposed concentrically around an axis of said drilling or milling head and having respective opposed bearing surfaces which are concavely curved in the axial direction and which are symmetrical to each other, one of said outer and inner bearing rings being fixed relative to said housing and the other of said outer and inner bearing rings being mounted for rotation about said axis and coupled to said drive shaft, a plurality of balls disposed between the curved bearing faces of said outer and inner bearing rings, the maximum spacing of said curved bearing faces from each other being equal to the diameter of said balls, and a driving part rotated by the motor for driving said balls around said axis along the curved bearing surface of the fixed bearing ring, said driving part exerting an axial force against said balls to urge said balls into force-transmitting engagement with said bearing surfaces, whereby the rotationally mounted bearing ring and the drive shaft are caused to rotate.