Patent ID: 6185896
Filing Date: 2001-02-13
Classification: F16B

Abstract:
A 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 drilling a hole within a 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.degree. than said first predetermined angular disposition of said leading flank; andwherein 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 disposed toward said head end of said elongate shank, and a second end 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 member by said drilling tip.