Screw head with release resisting teeth - has teeth number and size dimensioned for optimum indentation of component

摘要

A screw head (or a nut) has a pressure surface provided with an annular array of saw-tooth type teeth for resisting release of the screw. The number and size of the teeth, and the mean dia. of the array, are chosen for optimum indentation of the component to be secured. Pref. the area covered by the array is at least 1.4 times and pref. 2.3 times greater than the cross-sectional area of the screw concerned. The inside dia. of the array is pref. > the dia. of the clearance hole for the screw. The teeth may have slightly flattened tips.