Cryogenic connection method and means

Abstract

A reusable connecting device is disclosed which utilizes a heat recoverable metallic band disposed about a resilient member such as the tines of a forked member. Where the resilient member is a forked member, the forked member has at least two tines which are spaced from one another and which are elastically mounted so that they can be moved inwardly but, when so moved, exert an outward force. When it is desired to make a connection between this device and other objects, the object is placed between adjacent tines and the metallic band is caused to shrink thereby forcing the tines towards one another and causing them to contact and hold the object between them. The device is reusable in that when the temperature of the metallic band is lowered to cause the metal to transform to a martensitic state, it may be easily deformed due to a decrease in yield strength. The elastic nature of the tines or other resilient member causes them to push against the band resulting in a deformation of the band. This deformation permits the tines to move away from one another and releases the object held therebetween. However, once the metallic band is heated to a temperature at which the band reverts to its austenitic state, the band again contracts and moves the tines toward one another permitting a strong electrical or physical connection to be made.

What is claimed is: 
     
       1. A reusable connecting device comprising: a forked member having at least two tines which tines are capable of being moved inwardly and when so moved exert an outward force;   at least one band of a metallic material capable of having the property of heat recoverability imparted thereto and capable of changing dimensions so as to increase the transverse dimension of said band with the application of the force applied by said forked member when cooled to a temperature where it exists in the martensitic state and further being capable of changing dimensions so as to decrease the transverse dimension without the application of external force when warmed to a temperature at which it exists in its austenitic state, each band being large enough to permit it to be forced around at least a portion of the exterior of said tines when in its martensitic state and being small enough to move said tines inwardly when warmed to its austenitic state.   
     
     
       2. The device of claim 1 wherein said forked member has two tines. 
     
     
       3. The device of claim 1 wherein said device has one band. 
     
     
       4. The device of claim 3 wherein said band is a continuous band. 
     
     
       5. The device of claim 3 wherein said band is around a lower part of said fork. 
     
     
       6. The device of claim 3 wherein said band is a ring. 
     
     
       7. A reusable connecting device comprising: a forked member having at least two tines and being constructed from elastic material, said forked member having a cylindrical exterior located near the base of said tines;   a ring of a metallic material capable of having the property of heat recoverability imparted thereto and capable of changing dimensions so as to increase the transverse dimension of said ring with the application of the force supplied by said forked member when said ring is cooled to a temperature where it exists in its martensitic state, said ring being further capable of changing dimensions so as to decrease the transverse dimension without the application of external force when warmed to a temperature at which it exists in its austenitic state, said ring being large enough to permit it to be forced around said cylindrical exterior of said forked member when said ring is in its martensitic state and being small enough to move said tines inwardly when warmed to a temperature at which it exists in its austenitic state.   
     
     
       8. The device of claim 7 wherein said fork is fabricated from beryllium copper. 
     
     
       9. The device of claim 7 wherein said forked member has two tines. 
     
     
       10. The device of claim 7 wherein said ring exists in its austenitic state above about 0° C and in its martensitic state below about -40° C. 
     
     
       11. The device of claim 7 wherein said ring is fabricated from an alloy consisting essentially of about 49 atomic percent titanium, about 49 atomic percent nickel and about 2 atomic percent cobalt. 
     
     
       12. The device of claim 7 wherein said ring is fabricated from an alloy consisting essentially of about 48 atomic percent nickel, about 2 atomic percent iron and about 50 atomic percent titanium. 
     
     
       13. The device of claim 7 wherein said ring is fabricated from an alloy consisting essentially of about 52 atomic percent nickel, and about 48 atomic percent titanium. 
     
     
       14. The device of claim 7 wherein said ring is fabricated from a titanium, nickel and iron alloy within an area defined on a titanium, nickel and iron ternary phase diagram by a quadrilateral with its first corner at 49.1 percent titanium, 47.3 percent nickel and 3.6 percent iron; its second corner at 49.1 percent titanium, 48.8 percent nickel and 2.1 percent iron; its third corner at 50.2 percent titanium, 46.8 percent nickel and 3.0 percent iron and its fourth corner at 50.2 percent titanium, 45.1 percent nickel and 4.7 percent iron. 
     
     
       15. A device for stacking printed circuit boards said device being capable of forming both a physical and an electrical contact between adjacent boards, said device comprising: a beryllium copper forked member having two tines the exterior of said device having a lower cylindrical section, a middle cylindrical section having a larger outside diameter than said lower cylindrical section and an upper section having a larger outside dimension than said middle cylindrical section said upper and middle sections having a slot cut therebetween thereby forming two tines of said forked member said upper section further containing a cylindrical hollow portion aligned about axially with said lower cylindrical sections and having an inside dimension about equal to the outside dimension of said lower cylindrical section; and   a ring of a metallic material capable of having the property of heat recoverability imparted thereto and capable of changing dimension so as to increase the transverse dimension of said ring with the application of the force applied by said forked member when said ring is cooled to a temperature where it exists in its martensitic state said ring further being capable of changing dimensions so as to decrease the transverse dimension thereof without the application of external force when warmed to a temperature at which it exists in its austenitic state, said ring being large enough to permit it to be forced around said middle cylindrical section of said forked member when said ring is in its martensitic state, said ring being small enough to move said tines inwardly when warmed to a temperature at which it exists in its austenitic state.   
     
     
       16. A method for removably joining an object to a forked member having movable tines which tines tend to exert an outward force when they are forced inwardly, said method comprising: cooling a band of a metallic material capable of having the property of heat recoverability imparted thereto to a temperature where it exists in the martensitic state, said band having an inside dimension about 5 percent smaller than the outside dimension of the base of the tines of said forked member;   forcing the cooled band about the exterior of the base of said tines thereby increasing its size about 5 percent;   placing an object between the tips of said tines; and   warming said band to a temperature at which it exists in a martensitic state thereby causing said band to heat recover about the base of said tines and forcing the tips of said tines into contact with said object. .Iadd. 17. A circuit assembly comprising in combination:   a. a plurality of individual circuit boards in a spaced relationship and   b. plural interconnect means for adjoining the circuit boards in said spaced relationship, each of said interconnect means being mounted in an aperture in a circuit board and comprising: i. a forked member having at least two tines and an elongate pin portion, said forked member being mounted in said aperture so that the tines and the elongate pin portion are disposed on opposite sides of said circuit board, the tines being capable of being moved inwardly and when so moved to exert an outward force, and   ii. a band of a metallic material capable of having the property of heat recoverability imparted thereto and capable of changing dimension so as to increase the transverse dimension of said band with the application of the force applied by said forked member when the band is cooled to a temperature at where it exists in the martensitic state and further being capable of changing dimension so as to decrease the transverse dimension without the application of external force when warmed to a temperature at which it exits in its austenitic state, said band being large enough to permit it to be force around at least a portion of the exterior of said tines when in its martensitic state and being small enough to move said tines inwardly when warmed to its austenitic state; the elongate portion of selected interconnect means being received in and held by the tines of selected other interconnect means when said band is in its austenitic state to maintain the circuit boards in said spaced       
     
     
        relationship. .Iaddend..Iadd. 18.  A circuit assembly according to claim 17 wherein said interconnect means are electrically conductive and provide an electrical connection between said circuit boards. .Iaddend. .Iadd. 19. A circuit assembly comprising, in combination, a plurality of individual printed circuit boards, each of said boards having at least two opposed planar surfaces and interconnect means electrically connecting said board to another board each of said interconnect means including: i. metallic housing means mounted in an aperture through the respective board and electrically connected to the circuit thereon,   ii. an electrically conductive elongated, rigid member extending from the housing means in one direction into the region between boards,   iii. receiving means comprising a slotted, cylindrical bore in the housing means, said bore facing in a direction opposite from the elongated member and having opposite jaw members, an end portion of an elongated member of an interconnect means mounted to the next adjacent board being assembled to said bore, and   iv. thermally expandable means assembled to said receiving means for deflecting said jaw members to selectively expand and contract said bore to selectively create an interference fit between said bore and an assembled elongated member; said interconnect means being arranged on the planar surfaces of said boards. .Iaddend.