Screw threaded fastener and fastening system

A fastening system, comprising:

• a sheet of roofing material;
• a pair of thin metal battens respectively having overlapping regions including overlapped support walls, for supporting said sheet of roofing material, separated from each other by a predetermined space;
• and
• at least one screw threaded fastener comprising an elongate shank having a longitudinal axis;
• a drilling tip, having a predetermined diametrical extent, at one end of said elongate shank for respectively drilling first and second holes within said overlapped support walls of said pair of thin metal battens;
• a head at the opposite end of said elongate shank;
• and a screw thread extending over at least a part of the length of said elongate shank;
• wherein said at least one screw threaded fastener extends through said sheet of roofing material such that said screw head is engaged with said sheet of roofing material, said screw thread is threadably engaged with said overlapped support walls of said pair of thin metal battens so as to thereby attach said sheet of roofing material to said overlapped support walls of said pair of thin metal battens, and said drilling point has a length dimension which is greater than said predetermined space defined between said overlapped support walls of said pair of thin metal battens such that said drilling point can drill said second hole within a second one of said overlapped support walls of said pair of thin metal battens, after having drilled said first hole within a first one of said overlapped support walls of said pair of thin metal battens, prior to threaded engagement of said screw thread with said first one of said overlapped support walls of said pair of thin metal battens;
• wherein said screw thread comprises a first threaded portion having a constant thread crest diameter, a first end of said first threaded portion being disposed toward said head end of said elongate shank, and a second end of said first threaded portion being disposed toward said drilling tip;
• and a second threaded portion interposed between said second end of said first threaded portion and said drilling tip and having a tapered thread crest diameter with a first larger end thereof having a thread crest diameter substantially equal to said thread crest diameter of said first threaded portion, and a second smaller end thereof having a thread crest diameter which corresponds substantially to at least said predetermined diametrical extent of said drilling tip so as to promote proper co-action between said first threaded portion of said screw thread and said first and second holes formed within said pair of overlapped support walls of said pair of thin metal battens by said drilling tip;
• and
• wherein said screw thread comprises a leading flank which slopes outwardly at a first predetermined angular disposition with respect to said longitudinal axis of said elongate shank and in a direction away from said drilling tip, and a trailing flank which extends outwardly at a second predetermined angular disposition with respect to said longitudinal axis of said elongate shank which is a different angular disposition than said first predetermined angular disposition of said leading flank, said second predetermined angular disposition of said trailing flank being closer to 90° than said first predetermined angular disposition of said leading flank and subtending an angle relative to each one of said overlapped support walls of said pair of thin metal battens of not more than about 10° such that said trailing flank of said screw thread extends substantially parallel to each one of said support walls of said pair of thin metal battens surrounding said at least one screw threaded fastener when said screw threaded fastener is threadably engaged with said overlapped support walls of said pair of thin metal battens.

A screw threaded fastener for attaching roofing material to a support structure, comprising:

• an elongate shank having a longitudinal axis;
• a drilling tip, having a predetermined diametrical extent, at one end of said elongate shank for drilling a hole within a roofing member;
• a head at the opposite end of said elongate shank;
• and a screw thread extending over at least a part of the length of said elongate shank;
• wherein said screw thread comprises a leading flank which slopes outwardly at a first predetermined angular disposition with respect to said longitudinal axis of said elongate shank and in a direction away from said drilling tip, and a trailing flank which extends outwardly at a second predetermined angular disposition with respect to said longitudinal axis of said elongate shank which is a different angular disposition than said first predetermined angular disposition of said leading flank, said second predetermined angular disposition of said trailing flank being closer to 90° than said first predetermined angular disposition of said leading flank;
• and
• wherein further said screw thread comprises a first threaded portion having a first constant thread crest diameter and a first constant thread root diameter, a first end of said first threaded portion being disposed toward said head end of said elongate shank, and a second end of said first threaded portion being disposed toward said drilling tip;
• and a second threaded portion interposed between said second end of said first threaded portion and said drilling tip and having a tapered thread crest diameter and a tapered thread root diameter with a first larger end of said second threaded portion having a thread crest diameter and a thread root diameter substantially equal respectively to said first constant thread crest diameter and said first constant thread root diameter of said first threaded portion, and a second smaller end of said second threaded portion having a thread crest diameter and a thread root diameter which corresponds substantially to at least said predetermined diametrical extent of said drilling tip so as to promote proper co-action between said first threaded portion of said screw thread and the hole formed within the roofing member by said drilling tip;
• whereby when said fastener extends through the roofing member such that said screw head is engaged with the roofing member and said screw thread is threadably engaged with the support structure so as to thereby attach the roofing member to the support structure, said trailing flank of said screw thread will extend substantially parallel to the support structure surrounding said at least one screw threaded fastener so as to minimize distortion of the support structure under high load pull-out conditions.