Patent ID: 6105974
Filing Date: 2000-08-22
Classification: B23B,Y10S,Y10T

Abstract:
A chuck comprising:a holder body having a shank portion for insertion into a spindle of a machine tool, a gripping flange formed at one end of said shank portion, and a chuck sleeve that extends from said flange in a direction away from said shank portion in alignment with an axis of said shank portion, said chuck sleeve having a tapered outer circumferential surface whose diameter decreases from a base end adjacent said flange a tip end of said chuck sleeve;a clamp sleeve fitted onto the outer circumference of said chuck sleeve such that said clamp sleeve is rotatable and axially movable relative to said chuck sleeve, said clamp sleeve having a tapered inner circumferential surface whose diameter decreases from the base and adjacent to said flange toward the tip end of said clamp sleeve; andneedle rollers disposed between the outer circumferential surface of said chuck sleeve and the inner circumferential surface of said clamp sleeve over the entire circumference, said needle rollers inclining in the circumferential direction at a predetermined angle with respect to the center axes of said chuck sleeve and said clamp sleeve, and said clamp sleeve being rotated to cause said needle rollers to revolve spirally along the outer circumferential surface of said chuck sleeve while rotating about their own axes in order to decrease and restore the diameter of said chuck sleeve, whereina groove having a predetermined depth and a ring-like shape is formed in the end surface of said flange opposite said shank portion such that said groove extends along the outer circumference of the base end of said chuck sleeve through which said chuck sleeve is joined with said flange.