| 摘要 |
PURPOSE:To make a tool breakage detector compact, by enabling a detection element to move in a direction intersecting the axis of a tool and by providing detection elements with the same length when detecting the breakage of plural tools located on a concentric circle. CONSTITUTION:When drills 1 are at a standstill, pressurized oil is supplied to the butt-side pressure chamber 19 of a cylinder 16 through a pressurized oil inflow/outflow passage 18 to protrude a piston rod 24 and a detection element holder 23 is moved from a reference standstill position together with the piston rod. At that time, the detection element holder 23 is at first moved in the axial direction of the drill 1 by a cam follower 28 engaged in the cam groove 22 of the cylinder 16, and is thereafter moved in a direction intersecting the axial direction of the drill, as the holder is rotated while being supported on a bearing 25. For that reason, detection elements 30, 31 at first approach the drills 1 in their axial directions and then move in directions intersecting the axial directions, so that the detection elements come into contact with the drills. If the tip of each drill 1 is broken, no electrical current flows through a detection circuit for the drill. Therefore, the breakage of the drill 1 can be detected. |
