| 摘要 |
PURPOSE: To improve a drilling speed in application for all beds by rotatably supporting a bit at the end of an air hammer supported by a movable shoe at the end of a shield pipe so as to be movable in the axial direction. CONSTITUTION: A hammer case 22 constituting an air hammer is movably supported by a movable shoe 14 provided at the end of a shield pipe 12 via a seal 23 in the axial direction. A bit 24 is supported inside the end of the hammer case 22 via a seal 25 so as to be movable to the axial direction and rotatable around the axis. The bit 24 is connected to a drive shaft 32 for transmission of the rotation of a motor 28 so as to be slidable to the axial direction and subjected to strokes of an air-operated piston 38. The direction of the movable shoe 14 is controlled for precise drilling and the stroke and rotation of the bit 24 are used for powerful crushing force. |
