| 摘要 |
PURPOSE:To easily manufacture a die which has a desired die internal hole by pressing in a die nib and an external ring inside and outside of an internal ring which has plug bodies inserted some of through holes, and making the inside size of the die internal hole less than other parts at the plug body part. CONSTITUTION:A die nib 10 is exteriorly circular and has a diameter a little bit greater than the long axis of an elliptically-sectioned product in an axis- core direction. An intermediate ring 12 made of carbon tool steel has an external diameter a certain value less than the external diameter of the die nib 10 and also has plural through holes 18 in radius directions. Then, plug bodies 16 made of materials having a greater modulus of elasticity than the material of the intermediate ring 12 are pressed in some of the through holes 18 which face the ring 12. After the ring 12 wherein the plug bodies 16 are pressed is pressed in the internal hole of an external ring 14 having sufficient thickness, the die nib 10 is pressed in the internal hole of the ring 12 and shrinked in radius directions. In this case, the die nib 10 is shrinked inwardly more at parts where no plug body 16 is present than at the part where the plug bodies 16 are pressed, thus making the internal diameter section of the die nib 10 elliptic. |
