Fastener

Claim 1

A ONE-PIECE PLASTIC FASTENER FOR USE IN AN APERTURED PANEL HAVING A HEAD AND AN INTEGRAL SHANK, SAID SHANK INCLUDING A SUBSTANTIALLY RIGID FIRST LEG EXTENDING DOWNWARDLY AWAY FROM SAID HEAD, AT LEAST ONE SECOND LEG RESILIENTLY CONNECTED TO SAID FIRST LEG AT ITS EXTREMITY OPPOSITE THE HEAD AND EXTENDING UPWARDLY TOWARDS SAID HEAD IN DIVERGING RELATION TO SAID FIRST LEG, SAID FIRST LEG BEING SUBSTANTIALLY UNIFORM IN SECTION THROUGHOUT ITS LENGTH, SAID SECOND LEG HAVING SUBSTANTIALLY THE SAME WIDTH AS SAID FIRST LEG THROUGH ITS LENGTH, A FIRST SECTION OF SAID SECOND LEG EXTENDING FROM THE ATTACHMENT TO SAID FIRST LEG TO A POINT INTERMEDIATE THE LENGTH OF SAID SECOND LEG AND DECREASING IN RADIAL THICKNESS AS IT DIVERGES FROM SAID FIRST LEG, A SECOND SECTION OF SAID SECOND LEG PROGRESSIVELY INCREASING IN RADIAL THICKNESS FROM ITS JUNCTURE WITH SAID FIRST SECTION TO ITS FREE END, THE JUNCTURE OF SAID TWO SECTIONS BEING THE THINNEST RADIAL MEASUREMENT OF SAID SECOND LEG AND FORMING A CONCAVITY FACING SAID FIRST LEG, SAID JUNCTURE CONSTITUTING A FLEXIBLE RESILIENT HINGE LINE WHICH IS WEAKER THAN THE RESILIENT CONNECTION BETWEEN THE TWO LEGS, THE TRANSVERSE MEASUREMENT BETWEEN THE OUTER EXTREMITIES OF SAID TWO LEGS MEASURED ON A PLANE PERPENDICULAR TO THE AXIS OF THE FASTENER AND PASSING THROUGH SAID RESILIENT HING LINE OF SAID SECOND LEG NORMALLY BEING SUBSTANTIALLY GREATER THAN THE DIAMETER OF THE APERTURE IN THE COMPLEMENTARY PANEL WITH WHICH THE FASTENER IS TO BE ASSOCIATED, WHEREBY TELESCOPIC INSERTION OF THE SHANK IN A COMPLEMENTARY PANEL APERTURE CAUSES THE SECOND LEG TO FLEX INWARDLY TOWARD THE FIRST LEG UNTIL THE RESILIENT HINGE LINE OF SAID SECOND LEG PASSES THE VICINITY OF THE UNDERSURFACE OF THE PANEL WHEREUPON THE SECOND SECTION IS AUTOMATICALLY DEFLECTED INWARDLY TO FORM A SHOULDER TO UNDERLIE THE WORKPIECE AND THE FIRST SECTION OF SAID SECOND LEG SPRINGS OUTWARDLY UNDER THE PANEL DUE TO THE RELATIVE RESILIENT STRENGTHS OF THE JUNCTURES BETWEEN THE TWO SECTIONS OF SAID SECOND LEG AND THE FIRST SECTION OF SAID SECOND LEG WITH THE SAID FIRST LEG RESPECTIVELY.