Abstract: An air-driven rotary cutting tool including a grip part, a head part provided at a distal end of the grip portion, and a rotor of double-wheel type rotatably installed in a hollow portion formed in the head part. The rotor has a first turbine blade portion provided with a plurality of first turbine vanes surrounding the rotary axis and a second turbine blade portion integrally formed with the first turbine blade and having a plurality of second turbine vanes surrounding the rotary axis. The first turbine vane has, on its side when seen in a direction into the rotary axis, a concave shape concaved in a direction of rotation of the rotor, and the second turbine vane has, on its side, a concave shape concaving in a direction opposite from the first turbine vane.

Abstract: The air-driven rotary cutting tool comprising a grip part, a head part provided at a distal end of the grip portion; and a rotor of double-wheel type rotatably supported to a hollow portion formed in the head part around its rotary axis with a bearing, in which the rotor has a first turbine blade portion provided with a plurality of first turbine vanes surrounding the rotary axis and a second turbine blade portion integrally formed with the first turbine blade and having a plurality of second turbine vanes surrounding the rotary axis; the cutting tool is characterized by the first turbine vane having such a concave shape on its side seen in a direction into the rotary axis as to fall from upstream into downstream of its rotational direction of the rotor, and the second turbine vane having such a concave shape on its side as to fall into its opposite direction of the first turbine vane.

Abstract: A handpiece and a method for driving the handpiece are provided in which a sucking-back problem can be prevented with a simple structure. The handpiece 10 has a gripping portion 11 to be gripped by an operator, a head 15 mounted at a distal end of the gripping portion; and a wheel 55 rotatably mounted in an interior of the head. The head has an inlet 25 from which air is supplied to the wheel and an outlet 28 from which the air is discharged, the inlet and outlet being defined in the head, at least one buffer chamber 47 defined in the head, where the air is forced in due to a centrifugal force applied thereto by rotations thereof with the wheel and then accumulated under positive pressure, passages 66, 67, 68, and 34 for guiding the accumulated air from a neighborhood of the rotating wheel to an atmosphere, and a circumferential wall 44 mounted between the outlet and the wheel for providing a resistance to the air moving from the wheel toward the outlet.

Abstract: A handpiece and a method for driving the handpiece are provided in which a sucking-back problem can be prevented with a simple structure. The handpiece 10 has a gripping portion 11 to be gripped by an operator, a head 15 mounted at a distal end of the gripping portion; and a wheel 55 rotatably mounted in an interior of the head. The head has an inlet 25 from which air is supplied to the wheel and an outlet 28 from which the air is discharged, the inlet and outlet being defined in the head, at least one buffer chamber 47 defined in the head, where the air is forced in due to a centrifugal force applied thereto by rotations thereof with the wheel and then accumulated under positive pressure, passages 66, 67, 68, and 34 for guiding the accumulated air from a neighborhood of the rotating wheel to an atmosphere, and a circumferential wall 44 mounted between the outlet and the wheel for providing a resistance to the air moving from the wheel toward the outlet.

Abstract: An inventive medical/dental handpiece is characterized by including: a head part 2 that rotatably holds a rotor 24 for detachably holding a tool 91; and a gripped part 3 that supports, at its front end, the head part 2, and that is gripped by an operator, wherein the gripped part 3 includes a shank portion 31 extending from the head part 2, and a body portion 32 extending from a rear end of the shank portion 31 in the direction of an obtuse angle, wherein the axial flow turbine 5 is contained in the body portion 32, and wherein the handpiece further includes a rotation transmission mechanism for transmitting a rotation of the axial flow turbine 5 to rotate the rotor 24 of the head part 2.