| 摘要 |
PURPOSE:To reduce scratches on inner peripheral face generated at the time of expansion by further expanding the end of a penstock expanded by a rubber expanding mechanism by an expander mechanism. CONSTITUTION:For instance, seal rubber 6, flare rubber 4 and seal rubber 5 are arranged around a shaft 7 in this order, and a rubber expanding mechanism in which a ring 8 is fixed with a bolt 9 is provided at the tip. This rubber expanding mechanism is placed at the inside of expanded part of a penstock 1, and a die 3 is placed at the inside of it. The shaft 7 is moved and the rubber 4 is compressed through the ring 8, and the penstock 1 is expanded by applying internal pressure. Then, insufficiently expanded end of expanded part is expanded by the expander. By this way, it becomes not necessary to cut and remove the end of the penstock 1 after expansion, and scratches on inner peripheral face generated at the time of expansion is reduced. |
