| 摘要 |
A fastener 10 has a shank 14 presenting four surfaces 16. An opposed pair of the surfaces 16 have respective rows of radially extending wings 18 and the other two surfaces 16 have respective rows of angled wings 30. Although the wings 18 flex about straight lines at their junctures with the surfaces 16, the wings 30 flex about straight lines 36 spaced radially from the surfaces 16 because of thickened sections 34. This substantially increases the force required for removal of the fastener from an apertured workpiece as compared to the force required for introducing the fastener. <IMAGE> |
