| 摘要 |
<p>The method of forming a through-hole (70) is capable of preventing formation of burrs, improving machining efficiency and reducing machining cost. The method of forming a through-hole (70) in a circumferential wall of a tubular part of a work piece (10) comprises the steps of: setting the work piece (10) to a die (20); inserting a punch (30), which is provided to a rod-shaped metal core (32), into the tubular part; and pressing and moving a press pin (35) toward the die (20) together with the punch (30) so as to drive the punch (30) into an inner face of the circumferential wall and bore the through-hole (70). The press pin (35) is inserted in the tubular part via a guide through-hole (72), which has been formed in the circumferential wall of the work piece (10) and which is located on the opposite side of a prescribed position corresponding to the through-hole (70) to be bored, and contacts a surface of the metal core (32), which is located on the opposite side of the punch (30).</p> |
