| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a penetration machining head capable of stably cutting a second hole, accomplishing straightness required for the second hole, and preventing a torsion of the second hole. <P>SOLUTION: The penetration machining head 21 forming a cross-sectional figure 8 hole in a material having a first hole by machining the second hole partly overlapping the first hole, has a machining head section 22 provided with a cutting tip 26 arranged at a front end, and a guide section 23 provided with helical grooves 31 coaxially arranged on the rear side of the machining head section 22. <P>COPYRIGHT: (C)2012,JPO&INPIT |
