Quick change power tool chuck

A chuck device for holding a tool having a circumferentially round tool shaft or collet, the device comprising:

• a) a chuck body including an annular head portion having a distal end surface, a laterally spaced coupling end section and circumferential shoulder, an outer circumferential surface, and a central longitudinally extending bore with an inner circumferential bore surface to slidingly receive the tool shaft or collet with the tool axis aligned collinearly with the bore axis;
• b) the head portion including first and second slots that form a stationary segment and a pivotable segment having a bore-facing, tool grasping surface;
• c) the first slot is located in a first plane that extends parallel to the bore axis from the distal end surface and through one side of the annular end head portion to intersect the inner bore surface and outer circumferential surface of the head portion;
• d) the second slot is located in a second plane that extends normal to the central bore axis, is laterally spaced from and parallel to the distal end surface, and perpendicularly intersects the first slot to form the pivotable segment that causes the tool grasping surface to move between a rest position and a gripping position;
• e) whereby the tool grasping surface radially directs a compressive grasping force around the outer circumferential surface of the tool shaft or collet received in the bore;
• and
• f) a threaded aperture extending into the stationary and pivotable segments, and a tightener member is threadingly received in the threaded aperture that is tangentially disposed between inner and outer circumferential surfaces of the head portion, and between the distal end surface and the second slot;
• g) the tightener member, when tightened in the threaded aperture, is effective to produce a tension force in an amount sufficient to cause the tool grasping surface to grasp the tool shaft or collet received in the bore with a compressive force in an amount sufficient to hold the tool with a slip-torque of up to about 430 inch-lbs at a rotational speed of up to at least about 20,000 rpm.

A chuck device for holding a tool having a circumferentially round tool shaft or collet, the device comprising:

• a) a chuck body including an annular head portion having a distal end surface, a laterally spaced coupling end section, an outer circumferential surface, and a central longitudinally extending bore with an inner circumferential surface to slidingly receive the tool shaft or collet with the tool axis aligned collinearly with the bore axis;
• b) the head portion including a generally U-shaped, pivotally mounted arm having an inner curved bore-facing, tool grasping surface movable between a rest position and a gripping position whereby the tool grasping surface radially directs a compressive grasping force around the outer circumferential surface of the tool shaft or collet received in the bore;
• and
• c) a tightener member is threadingly received in a threaded aperture tangentially disposed between inner and outer circumferential surfaces of the head portion, and between the distal end surface and the laterally spaced coupling section of the head portion;
• d) the tightener member, when tightened, being effective to produce a tension force in an amount sufficient to cause the tool grasping surface to grasp the tool shaft or collet received in the bore in an amount of compressive force sufficient to hold the tool with a slip torque of up to about 430 inch-lbs at a rotational speed of up to at least about 20,000 rpm.