Controlled-drive sealing fastener

Claim 2

A controlled-drive sealing fastener comprising in combination: a an elongated shank having an entering end at one extremity; b a head of expanded cross section integral with said shank adjacent the other extremity; c a centrally-apertured, substantially-rigid washer assembled on the shank adjacent to, and extending at least to the radial extremity of, said head, the aperture being sufficient in size to accommodate the shank adjacent the head but insufficient to pass the head, said washer having at least an annular convex portion intermediate the radial peripheries thereof and disposed generally towards the head and a complementary annular concave portion disposed generally towards the entering end; d a centrally-apertured, non-metallic substantially-resilient washer of generally uniform thickness assembled on said shank adjacent said substantially-rigid washer and within the radial confines thereof prior to tightening of said fastener, said substantially-resilient washer being independent of said substantially-rigid washer at least as originally assembled on said shank, the periphery of the aperture of said substantially-resilient washer being stretched to resiliently grip said shank, outer portions of said substantially-resilient washer being relatively unstretched prior to tightening of said fastener, the resulting differential stresses holding the washer in an inverted generally frusto-conical configuration relative to said substantially-rigid washer and said head; said substantially-resilient washer thus being disposed to sealingly engage said shank, said substantially-rigid washer and an underlying workpiece surface upon tightening of the fastener thereagainst.

Claim 3

The controlled-drive fastener of claim 1 wherein the aperture of said substantially-rigid washer will pass said shank throughout its length and said substantially-rigid washer is held in place adjacent said head prior to tightening the fastener by said substantially resilient washer.

Claim 4

The controlled-drive sealing fastener of claim 1 wherein said elongated shank is threaded at least along a portion thereof.

Claim 5

The controlled-drive sealing washer of claim 1 wherein said substantially-rigid washer comprises steel and said substantially-resilient washer comprises rubber.

Claim 6

The controlled-drive sealing fastener of claim 1 wherein inner margins of said substantially-rigid washer are curved towards said shank.

Claim 7

The controlled-drive sealing washer of claim 1 wherein outer margins of said substantially-rigid washer are curved away from said shank.

Claim 8

The controlled-drive sealing washer of claim 1 wherein said substantially-rigid washer is fabricated from cold-rolled steel and said substantially-resilient washer is fabricated from neoprene synthetic rubber.

Claim 9

The controlled-drive sealing fastener of claim 1 wherein prior to tightening of said fastener the angle of the frustoconical configuration relative to the shank axis is about 30* to 70*.

Claim 10

The controlled-drive sealing fastener of claim 1 wherein said substantially-rigid and substantially resilient washers are independent of one another prior to tightening of said fastener.

Claim 11

The controlled-drive sealing fastener of claim 1 wherein the undersurface of said head and the contacting surface of said substantially-rigid washer are complementarily curved so as to provide self-centering characteristics to the assembly upon tightening of the fastener.

Claim 12

The controlled-drive sealing washer of claim 1 wherein the undersurface of said head and the contacting portion of said substantially-rigid washer have a complementary convex-concave relationship whereby the head and washer swivel to permit the fastener to be employed on angular surfaceS.

Claim 13

The controlled-drive sealing washer of claim 11 wherein the complementary concave and convex surfaces are mismatched to leave a gap therebetween adjacent the shank whereby resilient material is forced into the gap upon tightening of the fastener.

Claim 14

A controlled-drive sealing fastener comprising in combination: a an elongated threaded shank having an entering end at one extremity; b a head of expanded cross section integral with said shank adjacent the other extremity and having a generally convex undersurface; c a centrally-apertured, substantially-rigid washer assembled on the shank adjacentt to, and extending radially beyond, said head, the aperture being sufficient in size to accommodate the shank adjacent the head but insufficient to pass said head, said washer having an annular convex portion intermediate the radial peripheries thereof and disposed generally towards said head and a complementary annular concave portion disposed generally towards said entering end, inner head-side portions also being concavely curved to complement the contacting convex undersurface of said head; d a centrally-apertured, non-metallic substantially-resilient washer of generally uniform thickness assembled on said shank adjacent said substantially-rigid washer and within the radial confines thereof priro to tightening of said fastener, the periphery of the aperture of said sub-stantially-resilient washer being stretched to resiliently grip said shank, said substantially-resilient washer being independent of said substantially-rigid washer at least as originally assembled on said shank, outer portions of said substantially-resilient washer being relatively unstretched prior to tightening of said fastener, the resulting differential stresses holding the washer in an inverted generally frustoconical configuration relative to said substantially-rigid washer and said head, the conical sides being disposed at an angle of about 30* to 70* relative to the axis of the shank; said substantailly-resilient washer thus being disposed to sealingly engage said shank, said substantially-rigid washer and an underlying workpiece surface upon tightening of the fastener thereagainst.

Claim 15

A controlled-drive sealing fastener comprising in combination: a an elongated threaded shank having an entering end at one extremity; b a head of expanded cross section integral with said shank adjacent the other extremity and having a generally convex undersurface; c a centrally-apertured, substantially-rigid washer assembled on the shank adjacentt to, and extending radially beyond, said head, the aperture being sufficient in size to accommodate the shank adjacent the head but insufficient to pass said head, said washer having an annular convex portion intermediate the radial peripheries thereof and disposed generally towards said head and a complementary annular concave portion disposed generally towards said entering end, inner head-side portions also being concavely curved to complement the contacting convex undersurface of said head; d a centrally-apertured, non-metallic substantially-resilient washer of generally uniform thickness assembled on said shank adjacent said substantially-rigid washer and within the radial confines thereof priro to tightening of said fastener, the periphery of the aperture of said sub-stantially-resilient washer being stretched to resiliently grip said shank, said substantially-resilient washer being independent of said substantially-rigid washer at least as originally assembled on said shank, outer portions of said substantially-resilient washer being relatively unstretched prior to tightening of said fastener, the resulting differential stresses holding the washer in an inverted generally frustoconical configuration relative to said substantially-rigid washer and said head, the conical sides being disposed at an angle of about 30* to 70* relative to the axis of the shank; said substantailly-resilient washer thus being disposed to sealingly engage said shank, said substantially-rigid washer and an underlying workpiece surface upon tightening of the fastener thereagainst.

Claim 16

The controlled-drive sealing fastener of claim 13 wherein the convex undersurfaces of said head and the complementary concave surface on inner head-side portions of said substantially-rigid washer are mismatched to leave a gap therebetween adjacent the shank whereby resilient material is forced into the gap upon tightening of the fastener.