Recessed head fastener and driver combination
AssigneeResearch Engineering & Manufacturing, Inc.
InventorAlan Pritchard
Life of this patent
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Abstract
A screw recess and driver combination that comprises the use of varying frustums of differing cones to provide driver/recess contact faces that are elliptical.
Claims12
A fastener comprising:
- a head;
- a recess having a central cavity, in the head, that further comprises three radial extending-grooves that terminate within the head of the fastener;
- the central cavity comprising a lobular inner zone having three lobes having their maximum, circumscribing circle, positioned in line with the imaginary center of the radial extending grooves;
- wherein the radial extended grooves are developed from a frustum of a cone whose center line is angled away from that which is parallel to the axis of the fastener and provides an inwardly tapering, outer cone angle, of the recess that has the effect of providing elliptical and inwardly tapering elliptical sections as the radial extending grooves progress into the head of the fastener;
- and
- an additional central portion of the cavity being constructed as a frustum of a cone that culminates at the inscribing circle of the lobular inner zone.
A fastener of the kind specified that is characterized by a recess having a central cavity in a head that further comprises four radial extending grooves that terminate within the head of the fastener, wherein the central cavity comprises a lobular inner zone having four lobes with their maximum circumscribing circle positioned in line with the imaginary center of the radial extended grooves and where the radial extending grooves are developed from a frustum of a cone whose center line is angled away from that which is parallel to the axis of the fastener and provides an inwardly tapering outer cone angle of the recess that has the effect of providing elliptical and inwardly tapering elliptical sections as the radial extending grooves progress in to the head of the fastener;
- and
- wherein an additional central portion of the cavity being constructed as a frustum of a cone that culminates at the inscribing circle of the lobular inner zone.
A fastener of the kind specified that is characterized by a recess having a central cavity in the head and that further comprises two diametrically opposed radial grooves that terminate within the head of the fastener, wherein the central cavity comprises an oval inner zone having its maximum circumscribing diameter positioned in line with the imaginary center line of the diametrically opposed radial grooves and where the diametrically opposed radial grooves are developed from a frustum of a cone whose center line is angled away from that which is parallel to the axis of the fastener and provides an inwardly tapering outer cone angle of the recess that has the effect of providing elliptical and inwardly tapering elliptical sections as the radial grooves progress in to the head of the fastener;
- and
- wherein an additional central portion of the cavity being constructed as a frustum of a cone that culminates at the inscribing circle of the oval inner zone.
Dependencies are inferred from the claim text.