US5120175A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shape memory alloy fastener
Assignee: Lockheed Martin Corp
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Filing: 1991-07-15
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Granted: 1992-06-09
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Expires: 2011-07-15
Abstract
Abstract A fastener having an elongated shank formed of a shape memory alloy, a head at the upper end of the shank, and an annular segment at the lower end of said shank having a deformed cross-sectional shape suitable for insertion into an opening extending through adjacent workpieces. The annular segment has a frusto-conical trained shape that is larger than this opening. The annular segment radially flares from the deformed shape to an approximation of the trained shape when heated above a critical transformation temperature, thereby securing the fastener in place with respect to the workpieces. Alternatively, a sleeve made of a different material (e.g. aluminum) extending over a portion or the entire length of the fastener can be added for improved deformational characteristics, by providing the same frusto-conical shape through axial contraction of the shank.
Inventors
- 👤 William J. Arbegast
- 👤 Joseph H. Armstrong
- 👤 Brian J. Maclean
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:54
CPC Classifications
F; F16; F16B; F16B19/00; F16B19/04; F16B19/06; F27; F27D; F27D1/00; F27D1/14; F27D1/145; C; C08; C08L; C08L2201/00; C08L2201/12; F16B2200/00; F16B2200/77; Y; Y10; Y10S; Y10S411/00; Y10S411/90; Y10S411/901; Y10S411/902; Y10S411/909; Y10T; Y10T29/00; Y10T29/49; Y10T29/49826; Y10T29/49863; Y10T29/49865; Y10T29/49908; Y10T29/49938; Y10T29/49943; Y10T403/00; Y10T403/75
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
120 words
A one-piece fastener integrally formed of a shape memory alloy, adapted for insertion into an opening, said fastener comprising: an elongated shank having an upper end and a lower end adapted for insertion into said opening; a head at the upper end of said shank adapted to provide a predetermined limit for the maximum depth of insertion of said fastener into said opening; and a substantially annular segment extending from the lower end of said shank having a deformed shape suitable for insertion into said opening, and a substantially frusto-conical trained shape larger than said opening; said annular segment flaring radially outward from said deformed shape to an approximation of said trained shape when heated above a critical transformation temperature.
Claim 2
Dependent Claim
120 words
A one-piece fastener integrally formed of a shape memory alloy, adapted for insertion into an opening, said fastener comprising: an elongated shank having an upper end and a lower end adapted for insertion into said opening; a head at the upper end of said shank adapted to provide a predetermined limit for the maximum depth of insertion of said fastener into said opening; and a substantially annular segment extending from the lower end of said shank having a deformed shape suitable for insertion into said opening, and a substantially frusto-conical trained shape larger than said opening; said annular segment flaring radially outward from said deformed shape to an approximation of said trained shape when heated above a critical transformation temperature.
Claim 3
Dependent Claim
18 words
The fastener of claim 1, wherein said shape memory alloy is comprised of an iron-doped nickel titanium alloy.
Claim 4
Dependent Claim
17 words
The fastener of claim 1, wherein said shape memory alloy is comprised of nickel, titanium, and copper.
Claim 5
Dependent Claim
25 words
The fastener of claim 1, further comprising a sleeve extending along at least a portion of said shank and said annular segment of said fastener.
Claim 6
Dependent Claim
52 words
The fastener of claim 1, wherein said shank has a deformed cross-sectional shape suitable for insertion of said shank into said opening, and a trained cross-sectional shape larger than said opening, said shank expanding from said deformed shape to an approximation of said trained shape when heated above a critical transformation temperature.
Claim 7
Dependent Claim
185 words
A fastener adapted for insertion into an opening having two opposing sides separated by a predetermined thickness, said fastener comprising: an elongated sleeve adapted for insertion into said opening, having upper and lower ends and an internal cavity extending axially upward from said lower end; an elongated shank made of a shape memory alloy with upper and lower ends, having a deformed cross-sectional shape suitable for insertion into the internal cavity of said sleeve and a trained shape with a shorter length and larger cross-section than said deformed shape, such that heating said shank above a critical transformation temperature results in axial contraction and radial expansion of said shank causing radially expansive deformation of said sleeve; said lower end having a deformed cross-sectional shape suitable for insertion of said lower end and said sleeve into said opening, and a trained shape having a cross-section substantially greater than said deformed shape, such that heating said lower end above a critical transformation temperature results in said lower end causing deformation of an adjacent portion of said sleeve to form a lower head substantially larger than said opening.
Claim 8
Dependent Claim
185 words
A fastener adapted for insertion into an opening having two opposing sides separated by a predetermined thickness, said fastener comprising: an elongated sleeve adapted for insertion into said opening, having upper and lower ends and an internal cavity extending axially upward from said lower end; an elongated shank made of a shape memory alloy with upper and lower ends, having a deformed cross-sectional shape suitable for insertion into the internal cavity of said sleeve and a trained shape with a shorter length and larger cross-section than said deformed shape, such that heating said shank above a critical transformation temperature results in axial contraction and radial expansion of said shank causing radially expansive deformation of said sleeve; said lower end having a deformed cross-sectional shape suitable for insertion of said lower end and said sleeve into said opening, and a trained shape having a cross-section substantially greater than said deformed shape, such that heating said lower end above a critical transformation temperature results in said lower end causing deformation of an adjacent portion of said sleeve to form a lower head substantially larger than said opening.
Claim 9
Dependent Claim
38 words
The fastener of claim 6, further comprising an upper head extending radially outward from the upper end of said sleeve, adapted to provide a predetermined limit for the maximum depth of insertion of said sleeve into said opening.
Claim 10
Dependent Claim
27 words
The fastener of claim 7, wherein the length of said shank in its trained state between said upper and lower heads is less than the said thickness.
Claim 11
Dependent Claim
78 words
The fastener of claim 6, wherein the upper end of said shank has a deformed cross-sectional shape suitable for at least partial insertion of said upper end into said sleeve, and a trained shape having a cross-section substantially greater than said deformed shape, such that heating said upper end above a critical transformation temperature results in said upper end causing deformation of an adjacent portion of said sleeve to form an upper head substantially larger than said opening.
Claim 12
Dependent Claim
37 words
The fastener of claim 9, further comprising a head extending radially outward from an upper portion of said sleeve, adapted to provide a predetermined limit for the maximum depth of insertion of said sleeve in said opening.
Claim 13
Dependent Claim
26 words
The fastener of claim 9, wherein the length of said shank in its trained state between said upper and lower heads is less than said thickness.
Claim 14
Dependent Claim
18 words
The fastener of claim 6, wherein said shape memory alloy is comprised of an iron-doped titanium nickel alloy.
Claim 15
Dependent Claim
17 words
The fastener of claim 6, wherein said shape memory alloy is comprised of titanium, nickel and copper.
Claim 16
Dependent Claim
171 words
A fastener adapted for insertion into an opening having two opposing sides separated by a predetermined thickness, said fastener comprising: an elongated shank made of a shape memory alloy with upper and lower ends, adapted for insertion into said opening; a head at the upper end of said shank, adapted to provide a predetermined limit for the maximum depth of insertion of said fastener in said opening; a reduced segment made of a shape memory alloy extending from the lower end of said shank; and an annular collar adapted to fit over at least a portion of said reduced segment; said reduced segment having a deformed shape with cross-sectional dimensions such that said collar and said reduced segment can be inserted through said opening, and a trained shape with a cross-section substantially greater than said deformed shape, such that heating said reduced segment above a critical transformation temperature results in said reduced segment causing radial expansion and deformation of said collar to form a lower head substantially larger than said opening.
Claim 17
Dependent Claim
171 words
A fastener adapted for insertion into an opening having two opposing sides separated by a predetermined thickness, said fastener comprising: an elongated shank made of a shape memory alloy with upper and lower ends, adapted for insertion into said opening; a head at the upper end of said shank, adapted to provide a predetermined limit for the maximum depth of insertion of said fastener in said opening; a reduced segment made of a shape memory alloy extending from the lower end of said shank; and an annular collar adapted to fit over at least a portion of said reduced segment; said reduced segment having a deformed shape with cross-sectional dimensions such that said collar and said reduced segment can be inserted through said opening, and a trained shape with a cross-section substantially greater than said deformed shape, such that heating said reduced segment above a critical transformation temperature results in said reduced segment causing radial expansion and deformation of said collar to form a lower head substantially larger than said opening.
Claim 18
Dependent Claim
31 words
The fastener of claim 14, further comprising a retaining segment at the lower end of said reduced segment, adapted to retain said collar on said reduced segment in its deformed shape.
Claim 19
Dependent Claim
37 words
The fastener of claim 14, wherein said shank has a trained shape with a shorter length than said deformed shape, such that heating said shank above a critical transformation temperature results in axial contraction of said shank.
Claim 20
Dependent Claim
37 words
The fastener of claim 14, wherein said shank has a trained shape with a larger cross-section than said deformed shape, such that heating said shank above a critical transformation temperature results in radial expansion of said shank.
Claim 21
Dependent Claim
18 words
The fastener of claim 14, wherein the deformed shape of said shank is substantially equal to said thickness.
Claim 22
Independent Claim
175 words
A method of fastening together a plurality of workpieces having an opening extending therethrough, said method comprising the following sequence of steps: forming a fastener made of a shape memory alloy into a predetermined trained shape and heat treating said fastener to a temperature above the critical transformation temperature for said shape memory alloy, said trained shape having: (a) an elongated shank having an upper end and a lower end adapted for insertion into said opening; and (b) an expandable portion at the lower end of said shank having a cross-sectional shape larger than said opening; cooling said fastener in said trained shape to a temperature below said critical transformation temperature; deforming the expandable portion of said fastener into a deformed shape having a cross-sectional shape suitable for insertion into said opening; inserting said fastener in its deformed state into said opening; and heating said fastener to a temperature above said critical transformation temperature, thereby causing said lower portion of said fastener to transform from said deformed shape to an approximation of said trained shape.
Claim 23
Independent Claim
175 words
A method of fastening together a plurality of workpieces having an opening extending therethrough, said method comprising the following sequence of steps: forming a fastener made of a shape memory alloy into a predetermined trained shape and heat treating said fastener to a temperature above the critical transformation temperature for said shape memory alloy, said trained shape having: (a) an elongated shank having an upper end and a lower end adapted for insertion into said opening; and (b) an expandable portion at the lower end of said shank having a cross-sectional shape larger than said opening; cooling said fastener in said trained shape to a temperature below said critical transformation temperature; deforming the expandable portion of said fastener into a deformed shape having a cross-sectional shape suitable for insertion into said opening; inserting said fastener in its deformed state into said opening; and heating said fastener to a temperature above said critical transformation temperature, thereby causing said lower portion of said fastener to transform from said deformed shape to an approximation of said trained shape.
Claim 24
Dependent Claim
37 words
The method of claim 19, wherein said fastener further comprises a head at the upper end of said shank adapted to provide a predetermined limit for the maximum depth of insertion of said fastener in said opening.
Claim 25
Dependent Claim
21 words
The method of claim 19, wherein said fastener further comprises a sleeve extending along at least a portion of said shank.
Claim 26
Dependent Claim
21 words
The method of claim 19, wherein said expandable portion has a substantially cylindrical deformed shape, and a substantially frusto-conical trained shape.
Claim 27
Dependent Claim
52 words
The method of claim 19, wherein said shank has a deformed cross-sectional shape suitable for insertion of said shank into said opening, and a trained cross-sectional shape larger than said opening, said shank expanding from said deformed shape to an approximation of said trained shape when heated above said critical transformation temperature.
Claim 28
Independent Claim
246 words
A method of fastening together a plurality of workpieces having an opening extending therethrough, said method comprising the following sequence of steps: forming a fastener made of a shape memory alloy into a predetermined trained shape and heat treating said fastener to a temperature above the critical transformation temperature for said shape memory alloy, said trained shape having: (a) an elongated shank having an upper end and a lower end; (b) a lower annular segment extending from the lower end of said shank having a cross-sectional shape larger than said shank; and (c) an upper annular segment extending from the upper end of said shank having a cross-sectional shape larger than said shank; cooling said fastener in said trained shape to a temperature below said critical transformation temperature; deforming at least one of said annular segments into a deformed shape having a smaller cross-section than its trained shape; inserting said fastener in its deformed state into an elongated annular sleeve adapted to receive said shank and said deformed annular segment; deforming said deformed annular segment into a shape having a cross-section sufficiently large to retain said fastener within said sleeve; inserting said fastener into said opening; and heating said fastener to a temperature above said critical transformation temperature, thereby causing said lower annular segment to transform from said deformed shape to an approximation of its trained shape, and thereby causing deformation of at least a portion of said sleeve to a shape larger than said opening.
Claim 29
Independent Claim
246 words
A method of fastening together a plurality of workpieces having an opening extending therethrough, said method comprising the following sequence of steps: forming a fastener made of a shape memory alloy into a predetermined trained shape and heat treating said fastener to a temperature above the critical transformation temperature for said shape memory alloy, said trained shape having: (a) an elongated shank having an upper end and a lower end; (b) a lower annular segment extending from the lower end of said shank having a cross-sectional shape larger than said shank; and (c) an upper annular segment extending from the upper end of said shank having a cross-sectional shape larger than said shank; cooling said fastener in said trained shape to a temperature below said critical transformation temperature; deforming at least one of said annular segments into a deformed shape having a smaller cross-section than its trained shape; inserting said fastener in its deformed state into an elongated annular sleeve adapted to receive said shank and said deformed annular segment; deforming said deformed annular segment into a shape having a cross-section sufficiently large to retain said fastener within said sleeve; inserting said fastener into said opening; and heating said fastener to a temperature above said critical transformation temperature, thereby causing said lower annular segment to transform from said deformed shape to an approximation of its trained shape, and thereby causing deformation of at least a portion of said sleeve to a shape larger than said opening.
Claim 30
Dependent Claim
36 words
The method of claim 24, wherein said sleeve further comprises a head adjacent to said upper annular segment adapted to provide a predetermined limit for the maximum depth of insertion of said fastener, in said opening.
Claim 31
Dependent Claim
22 words
The method of claim 24, wherein said lower annular segment has a substantially cylindrical deformed shape, and a substantially frusto-conical trained shape.
Claim 32
Dependent Claim
59 words
The method of claim 24, wherein said shank has a deformed cross-sectional shape suitable for insertion of said shank into said sleeve, and substantially larger cross-sectional dimensions in its trained shape, said shank expanding from said deformed shape to an approximation of said trained shape when heated above said critical transformation temperature, thereby causing radial expansion of said sleeve.
Claim 33
Independent Claim
266 words
A method of fastening together a plurality of workpieces having an opening extending therethrough, said method comprising the following sequence of steps: forming a fastener made of a shape memory alloy into a predetermined trained shape and heat treating said fastener to a temperature above the critical transformation temperature for said shape memory alloy, said trained shape having: (a) an elongated shank having an upper end and a lower end; (b) a head at the upper end of said shank, adapted to provide a predetermined limit for the maximum depth of insertion of said fastener in said opening; (c) a reduced segment extending from the lower end of said shank having cross-section dimensions smaller than said shank; and (d) a retaining segment at the lower end of said reduced segment, having a cross-sectional dimensions larger than said reduced segment; cooling said fastener in said trained shape to a temperature below said critical transformation temperature; deforming said retaining segment and said reduced segment to smaller cross-sectional shapes; inserting the retaining segment and the reduced segment of said fastener through an elongated annular sleeve adapted to receive said reduced segment; deforming said retaining segment into a cross-sectional shape sufficiently large to retain said sleeve on said reduced segment; inserting said fastener into said opening; and heating said fastener to a temperature above said critical transformation temperature, thereby causing said reduced segment and said retaining segment to transform from said deformed shapes to an approximation of their trained shapes, and thereby causing radial expansion of at least a portion of said sleeve to a shape larger than said opening.
Claim 34
Independent Claim
266 words
A method of fastening together a plurality of workpieces having an opening extending therethrough, said method comprising the following sequence of steps: forming a fastener made of a shape memory alloy into a predetermined trained shape and heat treating said fastener to a temperature above the critical transformation temperature for said shape memory alloy, said trained shape having: (a) an elongated shank having an upper end and a lower end; (b) a head at the upper end of said shank, adapted to provide a predetermined limit for the maximum depth of insertion of said fastener in said opening; (c) a reduced segment extending from the lower end of said shank having cross-section dimensions smaller than said shank; and (d) a retaining segment at the lower end of said reduced segment, having a cross-sectional dimensions larger than said reduced segment; cooling said fastener in said trained shape to a temperature below said critical transformation temperature; deforming said retaining segment and said reduced segment to smaller cross-sectional shapes; inserting the retaining segment and the reduced segment of said fastener through an elongated annular sleeve adapted to receive said reduced segment; deforming said retaining segment into a cross-sectional shape sufficiently large to retain said sleeve on said reduced segment; inserting said fastener into said opening; and heating said fastener to a temperature above said critical transformation temperature, thereby causing said reduced segment and said retaining segment to transform from said deformed shapes to an approximation of their trained shapes, and thereby causing radial expansion of at least a portion of said sleeve to a shape larger than said opening.
Claim 35
Dependent Claim
15 words
The method of claim 28, wherein said retaining segment has a substantially frusto-conical trained shape.
Claim 36
Dependent Claim
52 words
The method of claim 28, wherein said shank has a deformed cross-sectional shape suitable for insertion of said shank into said sleeve, and a trained cross-sectional shape larger than said opening, said shank expanding from said deformed shape to an approximation of said trained shape when heated above said critical transformation temperature.
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