Tool driving device and method of producing drilled product

A tool driving device for use in drilling a workpiece comprising:

• a drill chuck for holding a drill;
• a motor configured to rotate the drill chuck;
• a casing housing the motor;
• and
• a vibrator configured to periodically reciprocate the drill chuck relatively to the casing in a tool axis direction during rotation of the drill chuck,
• wherein the vibrator is configured to distance the drill chuck away from the casing and toward the workpiece at a first speed smaller than a second speed for bringing the drill chuck back closer to the casing, and wherein the vibrator comprises a sliding surface formed directly or indirectly on one of the drill chuck and the casing, wherein the sliding surface includes surface grooving with an inner surface of the surface grooving being elongated in a circumferential length direction corresponding with a rotation direction of the vibrator, and with the surface grooving providing equally spaced level differences to enable the periodical reciprocation of the drill chuck relative to the casing in a tool axis direction during rotation of the drill, and wherein the vibrator includes a static ring and a rotary ring with the static ring remaining stationary with the casing while the rotary ring rotates relative to the static ring in going from a higher level to a lower level relative to the spaced level differences, and wherein there is a drop slope in the surface grooving that is greater than a return slope in the surface grooving, and wherein the surface grooving comprises radially spaced guidance edges each extending circumferentially and defining radially spaced end edging of the surface grooving that extends down into an exposed surface of a respective one of the static and rotary rings in which the surface grooving is provided, and wherein the vibrator includes:
• balls rollingly disposed between the drill chuck and the casing, the balls being disposed away from each other at regular intervals on a same circle;
• and
• the balls being contacted to the sliding surface while rolling during the rotation of the drill chuck,
• wherein the equally spaced level differences in the slide surface result in the balls falling simultaneously during normal rotation of the drill chuck, and
• the sliding surface changes smoothly from each level difference toward an adjacent level difference, and no level differences at which the balls ascend during the normal rotation of the drill chuck are formed on the sliding surface by the smoothly changing sliding surface, and wherein the vibrator further includes a ball retainer holding the balls rollingly, the ball retainer being rotatable around a tool axis, the balls rolling while rotating relatively to the drill chuck and the casing.

A tool driving device for use in drilling a workpiece comprising:

• a drill chuck for holding a drill;
• a motor configured to rotate the drill chuck;
• a casing housing the motor;
• and
• a vibrator configured to periodically reciprocate the drill chuck relatively to the casing in a tool axis direction during rotation of the drill chuck,
• wherein the vibrator is configured to distance the drill chuck from the casing and toward the workpiece at a first speed smaller than a second speed for bringing the drill chuck back closer to the casing, and wherein the vibrator comprises a sliding surface formed directly or indirectly on one of the drill chuck and the casing, wherein the sliding surface includes surface grooving with an inner surface of the surface grooving being elongated in a circumferential length direction corresponding with a rotation direction of the vibrator, and with the surface grooving providing equally spaced level differences to enable the periodical reciprocation of the drill chuck relative to the casing in a tool axis direction during rotation of the drill chuck, and wherein the vibrator includes:
• balls rollingly disposed between the drill chuck and the casing, the balls being disposed away from each other at regular intervals on a same circle;
• and
• the balls being contacted to the sliding surface while rolling during the rotation of the drill chuck,
• wherein the balls fall simultaneously during normal rotation of the drill chuck into the equally spaced level differences, and wherein at least a part of the circumferentially extending surface grooving has a radially extending cross-section that defines an arc having a common radius as that of the balls, and
• the sliding surface changes smoothly from each level difference toward an adjacent level difference, and wherein the vibrator further includes a ball retainer holding the balls rollingly, the ball retainer being rotatable around a tool axis, the balls rolling while rotating relatively to the drill chuck and the casing.