To provide a means forming continuous bores through multiple workpieces with no difficulty without producing discs from remnants at a boring termination of each workpiece as a continuous boring method of multiple workpieces.
Boring is performed passing through end face joints Wj between each of the multiple workpieces W1 to W5 arranged with their end faces jointed with one another using a drill head D including a center side cutter bit 2, a peripheral side cutter bit 3, and an intermediate cutter bit 4 near chip discharge ports 11, 12 opened in a head front edge face 1a. In the drill head D for use, all cutting edges 2a to 4a of the center side cutter bit 2, the peripheral side cutter bit 3, and the intermediate cutter bit 4 form slopes rising toward a head center O, the center side cutter bit 2 separates an inner end 21 of the cutting edge 2a from the head center O, and the cutting edge 2a is disposed in parallel with a radius line R of the head above the center anterior to the radius line R in a cutting rotating direction.
| JP2007203461A | 2007-08-16 | |||
| JPS6445505A | 1989-02-20 | |||
| JP2007136565A | 2007-06-07 | |||
| JPH10501184A | 1998-02-03 |
Hiroshi Masaki
Yuko Mikami
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