| 摘要 |
<p>At least one rib is provided on the undersurface of a cap for a countersunk head screw with slots forming a cross. For pref. the ribs are arranged in a cross also, and are injection moulded from a mixture of nylons, in one piece with the rest of the cap. The ribs have the form of prongs standing on each side of the point where their extensions intersect. and their outside edges taper inwards the axis of insertion. The design ensures accurate positioning without damage, and eliminates the weakening esp. of small screws by a central bore through the head into which a peg is pushed.</p> |
