Patent ID: 8672049

Claim:
A vibration drill unit, comprising: a motor that is a drive source; a spindle which is driven and rotated in a rotation direction by the motor and is movable in an axial direction thereof; a first ratchet, coupled to the spindle, having convex and concave claws; a non-rotatable second ratchet having convex and concave claws engageable with the convex and concave claws of the first ratchet; and a main body frame for accommodating the motor, the spindle, and the first and second ratchets, wherein the respective claws of the first ratchet and second ratchet have a first linearly rising inclined surface formed so as to be separated from each other by being engaged in the rotation direction based on rotations of the first ratchet, a second linearly falling inclined surface having a greater slope in the reverse direction of the first inclined surface than that of the first inclined surface, a ridge portion that links the respective top parts of both the inclined surfaces with each other, and a flat part that links the respective bottom parts of both the inclined surfaces with each other, wherein when the second ratchet engages the first ratchet, the second ratchet imparts a force to the first ratchet, thereby causing vibration in the spindle, wherein a direction of the force imparted by the second ratchet to the first ratchet is in the axial direction of the spindle, wherein the first ratchet and the second ratchet are capable of rotating relative to each other from a state where the ridge portion of one claw of the first and second ratchets abuts with the flat part of the other claw of the first and second ratchets, wherein, in each of the claws, the flat part is longer than the ridge portion in the rotation direction, wherein a spring for causing the second ratchet to slide in the axial direction and pressing the second ratchet to the first ratchet side is compressed and mounted between the second ratchet and the main body frame, wherein vibration drill unit includes an elastic material for absorbing vibrations of the second ratchet such that propagation of vibrations to the main body frame is suppressed, and wherein the elastic material is disposed between the main body frame and the spring.