| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method of a circular material which can suppress the occurrence of thickness deviation, while suppressing the reduction in production efficiency.SOLUTION: A forging device (1) includes a pair of molds (2) and (3). One mold (3) includes a tubular member (5) and a circular member (4). The circular member (4) is arranged coaxially with the tubular member (5) in the tubular member (5). In a manufacturing method, a cylindrical material (10) is placed between a pair of molds (2) and (3). Further, the tubular member (5) is slid in an axial direction CL direction, protruding into the other mold (2) side than the circular member (4). Then, by carrying out the upset forging, the cylindrical material (10) is get into touch with an inner peripheral surface (51) of the tubular member (5). Subsequently, the tubular member (5) is retracted to pull out from the cylindrical material (10). Then, by carrying the upset forging, the cylindrical material (10) extending radially is made to get into touch with not only the surface of the circular member (4) but also an end face (52) of the tubular member (5) after retraction. |
