High-strength structural blind fastener for use in airplanes, rockets and the like

Claim 2

An assembled three-part high-strength structural blind fastener of a series having design-holding lengths t that vary by a predetermined design increment i for attaching together structural members of airplanes, rockets and the like and of different total thickness having aligneD openings therein and one side inaccessible or blind, said assembled blind fastener comprising: a relatively nonductile substantially homogeneous discrete metal screw part having a tensile strength of not less than about 140,000 p.s.i. and a ductility of approximately 15 to 40 percent measured by reduction of area comprising a cylindrical shank provided with a thread, a head formed integral with the blind end of said shank, said shank have driving means on the end thereof opposite to said head and a section of less strength than the strength of the minimum effective cross-sectional area of said shank at the head end of said means; a continuous cylindrical relatively ductile metal sleeve blind head part on said shank of said screw part adjacent to said head thereof and having a tensile strength between 50,000 and 145,000 p.s.i. and a ductility of about 40 to 76 percent measured by reduction of area and an outside diameter substantially equal to the diameter of said head of said screw part; and a metal nut part having an internal thread and a tensile strength of not less than about 140,000 p.s.i. and a ductility of approximately 15 to 40 percent measured by reduction of area threaded onto said shank of said screw part, said nut part having a tubularlike body portion and a head formed integral therewith at the nonblind end thereof for engaging the accessible or nonblind side of members secured together by the fastener and an axially extending frustoconical surface at its other end inclined outwardly with respect to its longitudinal axis and towards its nonblind end at an angle from about 15* to 22* for expanding the end of said sleeve blind head part adjacent thereto beyond the yield strength of the material thereof but under the ultimate strength thereof to form a blind head engaging the inaccessible side of members secured together by the fastener upon said end of said sleeve part being forced over said frustoconical surface of said nut part upon rotation of said screw part relative to said nut part in driving said fastener, said tubularlike body portion of said nut part having a plurality of external discrete impressions adjacent to said frustoconical surface and spaced from one another, said impressions being formed subsequent to assembly of said screw and nut parts whereby said internal and external threads of said nut and screw parts have discrete distorted portions only radially inwardly of said impressions to form thread interference locks between said screw part and said nut part; said tubularlike body portion of said nut part of said fastener plus any portion of said head of said nut part adapted to be received within the members which the fastener is to secure together having a design minimum grip length l equal to a design length t plus one-half of the design incremental length i and a design maximum grip length l equal to t + (i/2) + (d/6 + OR - 1), where d is the diameter of said body part of said nut part at said frustoconical surface and has a dimensional tolerance range of 0.002 inch and the length of said nut, i.e., the length of the body portion plus any portion of the head adapted to fit within the members which the fastener is to secure together, plus the axial length of the frustoconical surface has a dimensional tolerance range of 0.010 inch; whereby members secured together by said fastener having a total thickness within the design grip range of the fastener are embraced between heads engaging opposite sides thereof one of which heads is relatively hard but more ductile than the screw part and the frustoconical surface of said nut is located wholly beyond the blind side of the members.

Claim 3

A series of assembled three-part high-strength structural blind fasteners having design holding lengths t that vary by a predetermined design increment i for attaching together structural members of airplAnes, rockets and the like and of different total thickness having aligned openings therein and one side inaccessible or blind, each of the assembled blind fasteners of the series comprising: a relatively nonductile substantially homogeneous discrete metal screw part having a tensile strength of not less than about 140,000 p.s.i. and a ductility of approximately 14 to 40 percent measured by reduction of area comprising a cylindrical shank provided with a thread, a head formed integral with the blind end of said shank said shank having driving means on the end thereof opposite to said head and a section of less strength that the strength of the minimum effective cross-sectional area of said shank at the head end of said means; a continuous cylindrical relatively ductile metal sleeve blind head part on said shank of said screw part adjacent to said head thereof and having a tensile strength between 50,000 and 145,000 p.s.i. and a ductility of about 40 to 76 percent measured by reduction of area and an outside diameter substantially equal to the diameter of said head of said screw part; and a metal nut part having an internal thread and a tensile strength of not less than about 140,000 p.s.i. and a ductility of approximately 15 to 40 percent measured by reduction of area threaded onto said shank of said screw part, said nut part having a tubularlike body portion and a head formed integral therewith at the nonblind end thereof for engaging the accessible or nonblind side of members secured together by the fastener and an axially extending frustoconical surface on its other end inclined outwardly with respect to its longitudinal axes and towards its nonblind end at an angle from about 15* to 22* for expanding the end of said sleeve blind head part adjacent thereto beyond the yield strength of the material thereof but under the ultimate strength thereof to form a blind head engaging the inaccessible side of members secured together by the fastener upon said end of said sleeve part being forced over said frustoconical surface of said nut part upon rotation of said screw part relative to said nut part in driving said fastener, said tubularlike body portion of said nut part having a plurality of external discrete impressions adjacent to said frustoconical surface and spaced from one another, said impressions being formed subsequent to assembly of said screw and nut parts whereby said internal and external threads of said nut and screw parts have discrete distorted portions only radially inwardly of said impressions to form thread interference locks between said screw part and said nut part; said tubularlike body portion of said nut part of each of said fastener plus any portion of said head of said nut part adapted to be received within the members which the fastener is to secure together having a design minimum grip length 1 equal to a design length t plus one-half of the design incremental length of said body part of said nut part at said frustoconical surface, d'' is the smaller diameter of the frustoconical surface and a is the angle in the axial plane of said frustoconical surface with respect to the longitudinal central axis of the nut part and v is the tolerance variation of the length of the body portion plus any portion of the head adapted to fit within the members which the fastener is to secure together plus the axial length of the frustoconical surface; whereby members secured together by said fasteners having a total thickness with the design grip range of the fastener are embraced between heads engaging opposite sides thereof one of which heads is relatively hard but more ductile than the screw part and the frustoconical surface of said nut is located wholly beyond the blind side of the members.

Claim 4

A series of assembled three-part high-strength structural blind fasteners having design holding lengths t that vary by a predetermined design increment i for attaching together structural members of airplAnes, rockets and the like and of different total thickness having aligned openings therein and one side inaccessible or blind, each of the assembled blind fasteners of the series comprising: a relatively nonductile substantially homogeneous discrete metal screw part having a tensile strength of not less than about 140,000 p.s.i. and a ductility of approximately 14 to 40 percent measured by reduction of area comprising a cylindrical shank provided with a thread, a head formed integral with the blind end of said shank said shank having driving means on the end thereof opposite to said head and a section of less strength that the strength of the minimum effective cross-sectional area of said shank at the head end of said means; a continuous cylindrical relatively ductile metal sleeve blind head part on said shank of said screw part adjacent to said head thereof and having a tensile strength between 50,000 and 145,000 p.s.i. and a ductility of about 40 to 76 percent measured by reduction of area and an outside diameter substantially equal to the diameter of said head of said screw part; and a metal nut part having an internal thread and a tensile strength of not less than about 140,000 p.s.i. and a ductility of approximately 15 to 40 percent measured by reduction of area threaded onto said shank of said screw part, said nut part having a tubularlike body portion and a head formed integral therewith at the nonblind end thereof for engaging the accessible or nonblind side of members secured together by the fastener and an axially extending frustoconical surface on its other end inclined outwardly with respect to its longitudinal axes and towards its nonblind end at an angle from about 15* to 22* for expanding the end of said sleeve blind head part adjacent thereto beyond the yield strength of the material thereof but under the ultimate strength thereof to form a blind head engaging the inaccessible side of members secured together by the fastener upon said end of said sleeve part being forced over said frustoconical surface of said nut part upon rotation of said screw part relative to said nut part in driving said fastener, said tubularlike body portion of said nut part having a plurality of external discrete impressions adjacent to said frustoconical surface and spaced from one another, said impressions being formed subsequent to assembly of said screw and nut parts whereby said internal and external threads of said nut and screw parts have discrete distorted portions only radially inwardly of said impressions to form thread interference locks between said screw part and said nut part; said tubularlike body portion of said nut part of each of said fastener plus any portion of said head of said nut part adapted to be received within the members which the fastener is to secure together having a design minimum grip length 1 equal to a design length t plus one-half of the design incremental length of said body part of said nut part at said frustoconical surface, d'' is the smaller diameter of the frustoconical surface and a is the angle in the axial plane of said frustoconical surface with respect to the longitudinal central axis of the nut part and v is the tolerance variation of the length of the body portion plus any portion of the head adapted to fit within the members which the fastener is to secure together plus the axial length of the frustoconical surface; whereby members secured together by said fasteners having a total thickness with the design grip range of the fastener are embraced between heads engaging opposite sides thereof one of which heads is relatively hard but more ductile than the screw part and the frustoconical surface of said nut is located wholly beyond the blind side of the members.

Claim 5

An assembled three part high strength structural blind fastener for connecting together structural members of airplanes, rocKets and the like, said assembled blind fastener comprising: a relatively nonductile substantially homogeneous discrete metal screw part having a tensile strength of not less than about 140, 000 p.s.i. and a ductility of approximately 15 to 40 percent measured by reduction of area comprising a cylindrical shank provided with a thread, a head formed integral with the blind end of said shank, said shank having driving means on the end thereof opposite to said head and a section of less strength than the strength of the minimum effective cross-sectional area of said shank at the head end of said means; a continuous cylindrical relatively ductile metal sleeve blind head part on said shank of said screw part adjacent to said head thereof and having a tensile strength between 50,000 and 145,000 p.s.i. and a ductility of about 40 to 76 percent measured by reduction of area and an outside diameter substantially equal to the diameter of said head of said screw part; and a metal nut part having an internal thread and a tensile strength of not less than about 140,000 p.s.i. and a ductility of approximately 15 to 40 percent measured by reduction of area threaded onto said shank of said screw part, said nut part having a tubularlike body portion and a head formed integral therewith at the nonblind end thereof for engaging the accessible or nonblind side of members secured together by the fastener and an axially extending frustoconical surface on its other end inclined outwardly with respect to its longitudinal axis and towards its nonblind end at an angle from about 15* to 22* for expanding the end of said sleeve blind head part adjacent thereto beyond the yield strength of the material thereof but under the ultimate strength thereof to form a blind head engaging the inaccessible side of members secured together by the fastener upon said end of said sleeve part being forced over said frustoconical surface of said nut part upon rotation of said screw part relative to said nut part in driving said fastener, said tubularlike body portion of said nut part having a plurality of external discrete impressions adjacent to said frustoconical surface and spaced from one another, said impressions being formed subsequent to assembly of said screw and nut parts whereby said internal and external threads of said nut and screw parts have discrete distorted portions only radially inwardly of said impressions to form thread interference locks between said screw part and said nut part.

Claim 6

An assembled three part high strength structural blind fastener for connecting together structural members of airplanes, rocKets and the like, said assembled blind fastener comprising: a relatively nonductile substantially homogeneous discrete metal screw part having a tensile strength of not less than about 140, 000 p.s.i. and a ductility of approximately 15 to 40 percent measured by reduction of area comprising a cylindrical shank provided with a thread, a head formed integral with the blind end of said shank, said shank having driving means on the end thereof opposite to said head and a section of less strength than the strength of the minimum effective cross-sectional area of said shank at the head end of said means; a continuous cylindrical relatively ductile metal sleeve blind head part on said shank of said screw part adjacent to said head thereof and having a tensile strength between 50,000 and 145,000 p.s.i. and a ductility of about 40 to 76 percent measured by reduction of area and an outside diameter substantially equal to the diameter of said head of said screw part; and a metal nut part having an internal thread and a tensile strength of not less than about 140,000 p.s.i. and a ductility of approximately 15 to 40 percent measured by reduction of area threaded onto said shank of said screw part, said nut part having a tubularlike body portion and a head formed integral therewith at the nonblind end thereof for engaging the accessible or nonblind side of members secured together by the fastener and an axially extending frustoconical surface on its other end inclined outwardly with respect to its longitudinal axis and towards its nonblind end at an angle from about 15* to 22* for expanding the end of said sleeve blind head part adjacent thereto beyond the yield strength of the material thereof but under the ultimate strength thereof to form a blind head engaging the inaccessible side of members secured together by the fastener upon said end of said sleeve part being forced over said frustoconical surface of said nut part upon rotation of said screw part relative to said nut part in driving said fastener, said tubularlike body portion of said nut part having a plurality of external discrete impressions adjacent to said frustoconical surface and spaced from one another, said impressions being formed subsequent to assembly of said screw and nut parts whereby said internal and external threads of said nut and screw parts have discrete distorted portions only radially inwardly of said impressions to form thread interference locks between said screw part and said nut part.