| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the drill tip coming into collision with a workpiece, to absorb impact of the drill tip coming into collision with the workpiece, and to eliminate sudden change of reciprocating speed of the drill when the drill tip pierces through the workpiece. SOLUTION: An actuator 13 is provided on a supporting frame 3, connecting the connection 5a of a drilling tool head 5 to a movable body 15 reciprocating toward the cutting direction by the actuation of the actuator 13 to compose the drilling tool head 5 so that it can slightly move toward the cutting direction with respect to the movable body 15, and an energizing member 43 energizing the drilling tool head 5 toward the cutting direction with respect to the movable body 15, and a locking means 45 for securing the drilling tool head 5 to the movable body 15 are provided. The reciprocating speed of the drilling tool head 5 is controlled to be switched over from rapid traverse speed to cutting feed speed when the drilling tool head 5 is detected by a proximity sensor 57 that it has slightly moved toward the cutting direction with respect to the movable body 15.
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