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An impact hammer drill capable of performing drilling operation at a high speed with low noise and without requiring a large thrust. The drill includes a main shaft rotatable by an output shaft of a motor, and a spindle having an impact-receiving section and disposed over the main shaft slidably in

An impact hammer drill capable of performing drilling operation at a high speed with low noise and without requiring a large thrust. The drill includes a main shaft rotatable by an output shaft of a motor, and a spindle having an impact-receiving section and disposed over the main shaft slidably in its axial direction and rotatable together with the rotation of the main shaft. A piston is reciprocatingly slidably disposed over the main shaft for impacting against the impact-receiving section. A piston drive unit is disposed for driving the piston with a compressed fluid. A compressed fluid supplying unit is disposed for supplying the compressed fluid to the piston drive unit. A drill bit is attachable to the spindle. When performing drilling operation, the drill bit is imparted with a combined rotational motion and the reciprocal impact motion.

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What is claimed is: 1. A drilling machine comprising: a frame having one end; a motor fixed within the frame and having an output shaft extending toward the one end of the frame; a rotation shaft extending toward the one end of the frame and having an axis, the rotation shaft being coupled to the o

What is claimed is: 1. A drilling machine comprising: a frame having one end; a motor fixed within the frame and having an output shaft extending toward the one end of the frame; a rotation shaft extending toward the one end of the frame and having an axis, the rotation shaft being coupled to the output shaft of the motor so as to rotate therewith, the rotation shaft including a slidable section disposed over an end portion of the rotation shaft which is configured so as to be slidable with respect to the rotation shaft and so as to prevent rotation of the slidable section with respect to the rotation shaft, the slidable section having one end provided with a drill bit attachment section and another end serving as an impact-receiving section; a piston extending in parallel with an axial direction of the axis of the rotation shaft, and slidable in a reciprocatory manner in the axial direction to impact the another end of the slidable section; a piston drive unit reciprocally driving the piston with a compressed fluid; and a compressed fluid supplying unit disposed within the frame for supplying the compressed fluid to the piston drive unit. 2. The drilling machine as claimed in claim 1, wherein the compressed fluid supplying unit comprises: a coupling unit adapted to be coupled to a compressor which generates the compressed fluid; an impact path forming portion that forms an impact path which communicates the coupling unit with the piston drive unit; and an impact path flow controlling unit disposed at the impact path for controlling a flow rate of the compressed fluid running through the impact path. 3. A drilling machine comprising: a frame having one end; a motor fixed within the frame and having an output shaft extending toward the one end of the frame; a rotation shaft extending toward the one end of the frame and having an axis, the rotation shaft being coupled to the output shaft of the motor so as to rotate therewith, the rotation shaft including a slidable section having one end provided with a drill bit attachment section and another end serving as an impact-receiving section; a piston extending in parallel with an axial direction of the axis of the rotation shaft, and slidable in a reciprocatory manner in the axial direction to impact the impact-receiving section; a piston drive unit reciprocally driving the piston with a compressed fluid; and a compressed fluid supplying unit disposed within the frame for supplying the compressed fluid to the piston drive unit; wherein the compressed fluid supplying unit comprises: a coupling unit adapted to be coupled to a compressor which generates the compressed fluid; an impact path forming portion that forms an impact path which communicates the coupling unit with the piston drive unit; and an impact path flow controlling unit disposed at the impact path for controlling a flow rate of the compressed fluid running through the impact path; and wherein the rotating shaft comprises: a main shaft having one end, one end portion, and another end drivingly coupled to the output shaft, the main shaft being formed with grooves extending from the one end of the main shaft in the axial direction of an axis of the main shaft; and a cylindrical spindle functioning as the slidable section disposed over the one end portion of the main shaft, and slidable in the reciprocatory manner relative to the frame and the main shaft, the spindle having an inner peripheral surface, a front end functioning as the drill bit attachment section, and a rear end functioning as the impact-receiving section, the spindle also having protrusions protruding from the inner peripheral surface, each protrusion being slidably engageable with each groove to allow the spindle to be axially moved relative to the main shaft but prevent the spindle from being rotated relative to the main shaft. 4. The drilling machine as claimed in claim 3, wherein the piston is formed into a cylindrical shape, and is slidably disposed over the main shaft. 5. The drilling machine as claimed in claim 4, wherein the piston is concentric with the main shaft. 6. The drilling machine as claimed in claim 3, wherein the frame comprises a first frame having one end and housing therein the motor, and a second frame coupled to the one end of the first frame and housing therein the piston drive unit, the drill bit being protruding from the second frame when the drill bit is attached to the drill-bit attachment section. 7. The drilling machine as claimed in claim 6, wherein the first frame includes a first wall section disposed at a boundary between the first frame and the second frame; and wherein the piston drive unit comprises: the first wall section rotatably supporting the main shaft; a second wall section disposed in the second frame and fixedly supported thereto, the spindle extending through the second wall section and rotatably supported thereto; a cylinder disposed in the second frame and supported by the first wall section and the second wall section, the rotation shaft extending through the cylinder, and the cylinder having an inner peripheral surface with which the piston is slidable, the cylinder being formed with at least one vent hole communicating with the impact path for introducing the compressed fluid into an internal space of the cylinder, a rear space being defined by the cylinder, the first wall section, the main shaft, and a rear end of the piston, and a fluid discharge space being defined by the cylinder, the second wall section, and a front portion of the piston. 8. The drilling machine as claimed in claim 7, wherein the inner peripheral surface of the cylinder is provided with an annular inward projection at a position immediately ahead of the at least one vent hole; and wherein the piston has an inner diameter substantially equal to an outer diameter of the main shaft, and is disposed between the cylinder and the main shaft; and wherein the piston is movable between a rearmost position near the motor and a frontmost position abutting the impact-receiving section, and the piston has a front section having an outer diameter subsequently equal to an inner diameter of the annular inward projection, and has a rear section having an outer diameter greater than that of the front section and subsequently equal to an inner diameter of the cylinder, and wherein the piston is formed with a first hole selectively communicated with the fluid discharge space, and a second hole providing communication between the first hole and the rear space, the first hole being positioned ahead of the annular inward projection for communication with the fluid discharge space when the piston is moved to the frontmost position, and being positioned rearward of the annular inward projection for communication with the impact path through the at least one vent hole when the piston is moved to the rearmost position. 9. The drilling machine as claimed in claim 8, wherein the spindle has a hollow cylindrical shape defining therein a fluid passage extending in an axial direction thereof, the spindle being formed with a radial through-hole in communication with the fluid passage; and wherein the frame is formed with a first fluid path forming portion that forms a first fluid path providing fluid communication between the radial through-hole and the fluid discharge space. 10. The drilling machine as claimed in claim 3, wherein the spindle has a hollow cylindrical shape defining therein a fluid passage extending in an axial direction thereof, the spindle being formed with a radial through-hole in communication with the fluid passage; and wherein the frame is formed with a first fluid path forming portion that forms a first fluid path providing fluid communication between the radial through-hole and the compressed fluid supplying unit. 11. The drilling machine as claimed in claim 10, wherein the compressed fluid supplying unit further comprises: a cooling path forming portion that forms a cooling path allowing the coupling unit to communicate with the first fluid path; and a cooling path flow controlling unit disposed at the cooling path for controlling a flow rate of the compressed fluid running through the cooling path. 12. A drilling machine comprising: a frame; a motor disposed in the frame and having an output shaft; a main shaft coupled to the output shaft of the motor so as to rotate therewith; a spindle disposed over a portion of the main shaft and having one end provided with a drill bit attachment section and another end serving as an impact-receiving section, the spindle configured so as to be slideable with respect to the main shaft and so as to prevent rotation of the spindle with respect to the main shaft; a cylinder disposed in the frame, at least a portion of the main shaft being surrounded by the cylinder; a piston disposed between the cylinder and the main shaft and slidable in the reciprocatory manner to impact another end of the spindle; a piston drive unit reciprocally driving the piston with a compressed fluid; and a compressed fluid supplying unit disposed within the frame for supplying the compressed fluid to the piston drive unit.