PURPOSE: To increase a forming accuracy and to reduce the cost by press- forming a blank pipe with the upper and lower divided dies providing wavy forming face and by forming with bulging with compressing the blank pipe in an axial direction.
CONSTITUTION: The upper die 1 is divided into die pieces 1aW1c and supported freely movably by the upper part guide rail 10. By the connecting integration of these three die pieces a semi-circular recessed groove 2a is formed on the lower end face so as to coincide with the upper half part at the outside of the blank pipe P. The lower die 3 is divided into die pieces 3aW3d, supported by the lower part guide rail 11 and a recessed groove 4a is formed by the integration of the four die pieces. Pressing bodies 5, 5 are compressed with equal force and same speed from both sides simultaneously with closing the upper and lower dies 1, 3. In this case a bulging formation is performed by applying a hydraulic pressure from the inner part. The forming accuracy is thus increased and mass production can be performed, so the production cost can be reduced.
URABE YOSHIO
TAMURA KENJI
| JPS5719114A | 1982-02-01 | |||
| JPS57165134A | 1982-10-12 |