| 摘要 |
PROBLEM TO BE SOLVED: To restrain the accumulation on the upper portion of the land portion and prolong the life of a die having a land portion at its lower end portion larger in outside diameter than its remaining portion by providing the portion above the land of the die with multiple knurl-like convex portions, when work blanks are formed into a specified shape by cold, warm, or hot forging. SOLUTION: Above a land portion 4 of a die 1, multiple knurl-like convex portions 2 are provided. The diameter connecting the highest points 6 of the convex portion is made smaller than the diameter of the land portion 4. The width 3 of the convex portion is not larger than 1/10 of the outside diameter of the land portion 4. It is desirable to make the convex portions 2 by rolling because it is lower in cost than machining. The die 1 moves from the top dead center to the bottom dead center of the press to process the work blank into a specified shape. When the die 1 is pulled up from the bottom dead center to the top dead center, the land portion 4 gouges the work blank leaving the accumulation on the top of the land portion 4, but the convex portions 2 provided above the land portion 4 prevent this.
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