| 摘要 |
PURPOSE:To produce a connecting rod which has no defects such as bent and has a good shape by a closed-die forging method at a high material yield and with simple means by using a blank which is preliminarily produced by taking the metal distribution in the longitudinal direction of the connecting rod into consideration. CONSTITUTION:Such blank 10 which suppresses the flow of the metal in the longitudinal direction at the large end and small end of the connecting rod 1 and forces quickly the material to arrive in the direction intersecting orthogonally therewith is prepd. More specifically the metal of the material in the part 11 corresponding to at least, for example, the large end 2 is made into a spherical shape or the shape resembling thereto. Upper and lower punches 6a, 6b, 7a, 7b are first fixed in the retreat position of the stroke shown in the figure. The blank 10 is then imposed between upper and lower dies 5a and 5b and is thereafter compressed by the dies 5a, 5b by which an I section part 4 is formed to the prescribed shape. While the dies 5a, 5b are held closed, the stock is compressed by the punches 6a, 6b, 7a, 7b, by which only the large end 2 and small end 3 are formed to the prescribed shape.
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