| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent the runout of a drill for opening a second hole along a curved surface of a first hole formed when forming a workpiece, and to open the second hole straight thereby. <P>SOLUTION: A first hole 11b extending in the predetermined direction of a workpiece 11 when forming the cast workpiece 11 and a rectangular recessed groove 11f communicated with the first hole 11b and formed along the longitudinal direction of the first hole 11b are formed in the workpiece 11. A second hole 11d is opened in the workpiece 11 by a drill 12 so that a part of the second hole is across the predetermined direction in a partly overlapping manner on the first hole 11b. Further, when the second hole 11d is opened by the drill 12, and the drill 12 is passed through into the first hole 11b, a fore end of the drill 12 is passed through from one side face of the rectangular recessed groove 11f. Still further, when the second hole 11d is opened by the drill 12, and the drill 12 is run into the workpiece 11 from the inside of the first hole 11b, the fore end of the drill 12 is run into the other side face of the rectangular recessed groove 11f. <P>COPYRIGHT: (C)2012,JPO&INPIT |
