SELF-TAPPING SCREW

SELF-TAPPING SCREW HAVING AN AT LEAST PARTIALLY NON-ROUND ENVELOPING CURVE FOR THE THREAD AND HAVING A PENETRATING SECTION AND A RETAINING SECTION, IT BEING THE CASE THAT THE PENETRATING SECTION CONTAINS A PLURALITY OF SUCCESSIVE THREAD STAGES WHICH EACH HAVE AT LEAST ONE THREAD TURN AND, ALONG THE THREAD STAGE, HAVE ESSENTIALLY THE SAME, ALIGNED ENVELOPING CURVE WHICH RUNS EITHER CYLINDRICALLY OR ELLIPTICALLY ENVELOPING CURVE (ELLIPTICAL THREAD STAGE) BEING COMBINED SUCH THAT THE MAJOR AXES OF THE SUCCESSIVE ELLIPTICAL THREAD STAGES, FORMING A STAGE GROUP, ARE OFFSET WITH RESPECT TO ONE ANOTHER.