Fastener with anti-cross-threading point and method of assembly

{
  "publication_number": "US6328515B1",
  "country": "US",
  "kind": "B1",
  "title": "Fastener with anti-cross-threading point and method of assembly",
  "abstract": "A novel fastener member and a novel method of assembly are provided for engagement of the fastener member with a female member having an internally threaded bore. The fastener member includes a threaded shank portion and a novel point at a work entering end thereof. The point includes a radiused portion which is engaged within the female member threaded bore to start engagement of the fastener member therewith. In certain embodiments, the point further includes an unthreaded portion, which has a diameter that is slightly less than a minor diameter of the shank portion, connecting the radiused portion and the threaded portion. The radiused portion has a maximum diameter which is slightly less than a minor diameter of the threaded bore. The radiused portion may take many forms and, for example, may be spherical; partially spherical; or formed from a predetermined number of radiused portions integrally formed with each other. To engage the fastener member and the female member, the radiused portion is disposed within the threaded bore and thereafter, rotational movement and an end load are applied to one or the other of the fastener member or the female member. The radiused portion is completely inserted into the bore prior to engagement of the shank portion with the threads in the bore, and will promote lateral as well as pivotal moment as required to align the respective members to attain proper thread engagement.",
  "claims": [
    "1. A fastener member for engagement with a female member having an internally threaded bore, said fastener member comprising: a shank portion having thread turns thereon, said threaded shank portion having a work entering end including a truncated lead thread which forms an abrupt end face, said abrupt face of said truncated lead thread being perpendicular to centerline of said shank portion and being formed 360° around said shank portion; and an unthreaded bulbous point proximate to said abrupt end face of said therad turns comprising a radiused portion which defines a maximum diameter, said point adapated to engaged within the internally threaded bore of the female member, wherein said radiused portion promotes alignment prior to the start of engagement of the fastener member threads with the internally threaded bore of the female member.",
    "2. A fastener member as defined in claim 1, wherein said lead thread progresses from a partial to a full profile within one thread pitch.",
    "3. A fastener member as defined in claim 1, wherein said threads on said shank portion are of a 60° thread profile.",
    "4. A fastener member as defined in claim 1, wherein said radiused portion is formed from a predetermined number of radiused portions integrally formed with each other.",
    "5. A fastener member as defined in claim 1, wherein said point further includes a tapered portion, said tapered portion being integrally formed with said radiused portion.",
    "6. A fastener member as defined in claim 1, wherein said unthreaded bulbous point comprises a first radiused portion which defines a maximum diameter of said point and a second portion between said first radiused portion and said threaded shank portion, said second portion defining a diameter which is less than said maximum diameter.",
    "7. A fastener member as defined in claim 6, wherein said second portion has a length which is at least approximately one pitch of the thread turns on said threaded shank portion to space said first radiused portion apart from said shank portion.",
    "8. A fastener member as defined in claim 6, wherein said diameter of said second portion of said point is slightly less than a minor diameter of said threaded shank portion.",
    "9. A fastener member as defined in claim 1, wherein said point includes a generally spherical portion.",
    "10. A fastener member as defined in claim 1, wherein said point is partially generally spherical.",
    "11. A fastener member as defined in claim 1, wherein said point has a truncated end surface.",
    "12. A fastener member as defined in claim 1, wherein said shank portion further defines an opposite end to said work entering end and further includes a head at said opposite end.",
    "13. A fastener member as defined in claim 12, further including a multilobular recess in said head for engagement with a tool.",
    "14. A method of engaging a fastener member and a female member comprising the steps of: providing a fastener member having a shank portion including thread turns thereon and defining a central axis, said threaded shank portion having an unthreaded bulbous point at an end thereof and having a lead thread proximate to said point, said lead thread being truncated perpendicular to said central axis of said shank portion and being formed 360° around said shank portion to form an abrupt end face; providing a female member having an internally threaded bore and defining a central axis; engaging said point with said internally threaded bore of said female member in an off-angle condition wherein said central axis of said fastener member is angled relative to said central axis of said threaded bore; applying rotational movement and and end load to one or the other of said fastener member of said female member, thereby defining a driven member, while maintaining the other of said fastener member of said female member stationary, thereby defining a stationary member, such that said point is engaged with said female member to cause said fastener member to move around said point to promote alignment of said fastener member axis with said female member bore axis, and such that said abrupt end face is engaged with a top surface of said female member to cause said fastener member and said female member to move into proper alignment upon further rotation and end load to said driven member, and thereafter engaging said thread turns on said threaded shank portion with the internal threads in said threaded bore in said female member.",
    "15. A method as defined in claim 14, wherein said point is completely inserted into said internally threaded bore prior to engagement of said threaded shank portion with said threads in said threaded bore in said female member.",
    "16. A method as defined in claim 14, wherein said point comprises a first radiused portion which defines a maximum diameter of said point and a second portion between said first radiused portion and said threaded shank portion, said second portion defining a diameter which is less than said maximum diameter and having a length which is at least approximately one pitch of the thread turns on said threaded shank portion to space said first radiused portion apart from said shank portion, and wherein the spacing provided by said second portion between said first radiused portion and said threaded shank portion allows for the movement of said fastener member around said first radiused portion.",
    "17. A method of engaging a fastener member and a female member comprising the steps of: providing a fastener member having a shank portion including thread turns thereon and defining a central axis, said threaded shank portion having an unthreaded bulbous point at an end thereof and having a lead thread proximate to said point, said lead thread being truncated perpendicular to said central axis of said shank portion and being formed 360° around said shank portion to form an abrupt end face; providing a female member having an internally threaded bore and defining a central axis; engaging said point with said internally threaded bore of said female member in an offset condition wherein said central axis of said fastener member is generally parallel to but not aligned with said central axis of said threaded bore; contacting a top surface of said female member with said abrupt end face prior to engagement of said threades shank portion; applying rotational movement and an end load to one or the other of said fastener member or said female member, thereby defining a driven member, while maintaining the other of said fastener member or said remale member stationary, thereby defining a stationary member; applying a transverse moment to said driven member to cause said center axes to align to move said fastener member and said female member into proper alignment, thereby to engage said thread turns of said threaded shank portion with the internal threads in said threaded bore in said female member.",
    "18. A method as defined in claim 17, wherein said unthreaded bulbous point is completely inserted into said internally threaded bore prior to engagement of said threaded shank portion with said threads in said threaded bore in said female member."
  ],
  "description_excerpt": "This application claims the priority of provisional application Ser. No. 60/026,608 filed on Sep. 24, 1996, entitled “Fastener Member With Anti-cross-threading Point.”\n\nThis invention is generally directed to a threaded male fastener member having a novel point configuration which prevents the fastener member from cross-threading upon engagement with a correspondingly threaded female member and the method of assembly thereof. Either the fastener member or the female member may be driven, the other member being stationary during the assembly. While the discussion that follows is directed primarily to the situation wherein the fastener member is the driven element and the female or internally threaded member is stationary, it should be kept in mind that the fastener member may be stationary and the internally threaded member, such as a nut, may be driven. During automated or manual assembly of an externally threaded fastener member with an internally threaded member, such as a nut, a tapped bore in a workpiece or an internally threaded rivet staked to a workpiece, one of a number of conditions will occur at assembly. First, proper engagement of the male threaded fastener member with the female threaded member will be obtained which is an acceptable condition. Second, cross-threading will occur which is an unacceptable condition. Third, a no-start will result wherein the male threaded component rotates without effecting threaded engagement with the threaded female member which is also an unacceptable condition.",
  "cpc": [
    "F16B 35/047",
    "F16B 19/1045",
    "F16B 5/025"
  ],
  "ipc": [
    "F16B 19/10",
    "F16B 35/00",
    "F16B 35/04",
    "F16B 5/02"
  ],
  "assignees": [
    "TEXTRON INC"
  ],
  "inventors": [
    "DONOVAN STEVEN P"
  ],
  "filing_date": "1997-08-21",
  "publication_date": "2001-12-11",
  "grant_date": "2001-12-11",
  "priority_date": "1996-09-24",
  "application_number": "US-91616497-A",
  "family_id": "26701445",
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}