| 摘要 |
An expandable mandrel for use in the construction of pipes has a tubular sleeve (10) of rigid but flexible material, a mandrel contracting device in the form of a rubber sleeve (12) surrounding the tubular sleeve (10) and an expanding device (14) inside the tubular sleeve (10). The tubular sleeve (10) has a longitudinal slot (11) and it assumes its undeformed shape when the mandrel is in the expanded state, whereby the mandrel will have a true cylindrical shape. <IMAGE> |
