| 摘要 |
The present invention provides a fastener for securing workpieces together which has a stem having an enlarged head at one end thereof that has a cavity therethrough, a main sleeve and an expander sleeve. The expander sleeve is adapted to move into a bore of the main sleeve to radially expand the main sleeve to form a first blind head for clamping the workpieces together in response to a first axial force. The enlarged stem head is adapted to move, without any deformation thereto, into a bore of the expander sleeve to radially expand the expander sleeve to form a second blind head to further clamp the workpieces together in response to a second axial force. The fastener further has a breakneck groove on the stem adapted to fracture the stem in response to a third axial force. |
