| 摘要 |
PURPOSE:To absorb an excess material to the recessed part by forming a connection rod part in an H shape cross section, by pressing the connection rod part by a punch with giving a back pressure to the recessed part after the die closing by inputting a die by forming a blank stock in the preformed article having the recessed part at the large end part and small end part with square cross section. CONSTITUTION:A preforming article 2 is formed with a forging finish by pressing it by the upper and lower punches 31, 41, after closing the die by setting the preforming article 2 between the upper die 11 and lower die 21. In this case, material reducings 97, 97 are formed by the projecting parts 37, 47 of the upper punch 31 and lower punch 41 on the upper and lower faces of the connection rod part 7 of the preforming article 2 and only the material of this material reducing portion is overfilled by being flowed to the large end part 3 and small end part 4. The excess material is absorbed as the variation in burr thickness by overcoming the set cushion pressure of the cushion pins 51, 61, 71, 81 giving a back pressure between the upper and lower recessed parts 5, 5, 6, 6.
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