| 摘要 |
Fastening device consisting of a sleeve of rectangular, conical, concave or convex form, the surface of which having one or more wings extending outwards or inwards and a fastening means expanding the sleeve, said wings having the form of rectangles, triangles, squares or parallel trapeziums, engaging or abutting angle varying between horizontal and vertical position, the slit of the sleeve varied in width and form relative to the friction against the wall of the hole, and the form and placing of the wings varying relative to the thickness and structure of the insertion material. <IMAGE> |
