| 摘要 |
PURPOSE:To form a through hole with one die by forming the through hole on the head part of a billet by pressing a separate punch having a discharging hole, after biting a formed pin upto halfway of the billet with a heading die. CONSTITUTION:The projection 23 at the tip of a formed pin 24 is bitten upto halfway of a billet (b) by pushing the billet (b) whose head part C is formed at the preceding stage into the forming hole 15b of the 2nd heading die 15 by holding it with the 2nd punch 34. A through hole is then made with the projection 23 penetrating the billet (b), when the 3rd punch 35 having an discharging hole 47 is abutted to the die 15 by moving to the left a punch block 28 by retreating a ram 27. In this case, the chips are discharged to the external part through the discharging hole 47. Consequently, there is no need for preparing plural sets of heading dies and the through hole can be formed with one heading die.
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