| 摘要 |
The present invention relates to apparatus for hydraulically expanding metal tubes of the type which employs an insertion mandrel carrying fluid into the tube with deformable sealing means axially located on either side of the fluid insertion point. In the prior an, deformation of the seal has been uncontrolled, resulting in occasions of asymmetrical extrusion of the seal into the gap between mandrel and tube, ruining the seal, interfering with removal of the mandrel, and resulting further in asymmetric tube expansion. The present invention provides a metal sleeve slidable on the mandrel to control centering of the seal, providing uniform axial deformation of the seal whereby radial expansion of the seal is made uniform about the circumference of the mandrel and extrusion of the seal into the gap is prevented. |
