| 摘要 |
<p>A screw anchor comprising an expanding body (10) made of plastics which is cylindrical and has an axial cavity (12) for the insertion and engagement of an expansion screw (11). The expanding body at least partially comprises a plurality of annular elements (13) which are mutually axially spaced and are mutually associated by connecting bridges (14). Each annular element is composed of sectors (15) which are mutually connected by diaphragms (16) which are equivalent to rotation hinges. The cavity has, at each annular element, a profile with regions which are narrower and wider than the core diameter of the corresponding expansion screw.</p> |
