Tube union assembly

Abstract: A fluid tight union assembly for connecting together two tubes (13 and 14) or two tubular members such as a tube (107) and a tubular fitting (106), comprising a sleeve (10 or 100), a first end portion of which is concentrically disposed around the end of the tube and a collar (25 or 101), wherein the external surface of the end of the tube has a series of spaced ring joints and a first end portion of the sleeve has an internal surface with a series of spaced circumferential lands (15) which are engaged in the ring joints, the first end portion of the sleeve having a tapered external surface portion (20) which decreases in diameter towards the first end of the sleeve and in which a raised lip (24) on the external surface of the sleeve is engaged by a ring (27) and a slot (28) on the internal surface of the collar, firmly to retain the collar on the sleeve. If two tubes are being joined, then a double ended sleeve is used with two collars.

Description: This invention relates to a tube union assembly and method of making a union assembly. Unions for tubing should effect a stable sealing joint to the tube without leakage of fluid from the union. More specifically, the invention relates to affixing two elements together such as joining the ends of tubes with a union or the end of a tube with a tubular fitting. In particular, the invention is concerned with the joinder of tubes or a tube and a fitting which are thin walled and of light weight, have high strength, and are used typically in the aircraft industry. It is known to connect the ends of tubes with a swaging sleeve which fits over the ends of the abutting ends of tubes. The swaging sleeve has an internal groove and land formation and an external tapered formation. An abutting collar on the outside surface of the sleeve causes the sleeve to deform inwardly. This in turn causes the ends of the walls of the tubes to deform into mating relationship with the grooves and lands. This creates an effective seal between the sleeve and the ends of the tubes. The construction for creating this engagement requires at least the collar over the outside surface and usually two more interengaging screw-threaded housing members over the sleeve which are permanently housed about the sleeve. The interengaging housing members are screw-threaded together by wrenching action on the housing members. This effects the union assembly. If the housing members are reverse screwed from the sleeve, the collar could be removed. This would leave only the sleeve and butting tube ends. There would then be no security between the abutting tube ends and the sleeve. Additionally, there is no way to remove the housing members from the tubes. As the housing members are relatively sturdy elements, they add considerable weight to the union. Naturally, in aircraft use, excess weight should be avoided. Accordingly, an object of the present invention is to provide a union assembly having a minium number of components and a method for forming the union assembly. The union assembly should effectively provide for sealing engagement between the ends of the tubes or tube and tubular fitting in a positive manner to avoid leakage. Another object of the invention is to provide a union assembly with a minimum number of components. According to one aspect of the invention, we provide a fluid tight union assembly comprising the end of a tube, a first end portion of a sleeve and a collar, the first end portion of the sleeve being concentrically disposed around the end of the tube and the collar being concentrically disposed around the first end portion of the sleeve, wherein the external surface of the end of the tube has a series of spaced ring joints, the first end portion of the sleeve has an internal surface with a series of spaced circumferential lands which are engaged in the ring joints, and the first end portion of the sleeve has an external surface with a tapered external face which decreases in diameter towards a first end of the sleeve, the union assembly being characterised by a raised lip on the external surface of the sleeve which is engaged by a ring and a slot on the internal surface of the collar firmly to retain the collar on the sleeve. Also according to the present invention, we provide a method for forming a fluid tight connection between the end of a tube and a first end portion of a sleeve, wherein the sleeve is concentrically disposed in abutting relationship around the end of the tube, the first end portion of the sleeve has an internal surface with a series of spaced circumferential lands, and the first end portion of the sleeve has an external surface with a tapered external face which decreases in diameter towards a first end of the sleeve, the method comprising the steps of positioning the first end portion of the sleeve over the end of the tube, positioning a swaging collar concentrically and in abutting relationship over the first end portion of the sleeve, and urging the collar axially towards the centre of the sleeve so that the tube is compressed inwardly by the lands on the internal surface of the sleeve, thereby deforming the wall of the tube and forming a series of spaced ring joints on the external surface of the tube which engage the lands, the method being characterised by the external surface of the sleeve having a raised lip and the internal surface of the collar having both a ring and a slot, such that, after the collar is urged axially toward the centre of the sleeve and a fluid tight connection is formed between the end of the tube and the sleeve, the lip on the sleeve is engaged by the ring and the slot on the collar firmly to retain the collar on the sleeve. The invention is particularly suited to forming a union assembly coupling the ends of two tubes and the assembly may comprise a sleeve for positioning centrally over a pair of tubes having their ends abutted together. The sleeve has an internal surface with circumferentially spaced apart lands and grooves. The external surface of the sleeve has a pair of tapered external surfaces decreasing in diameter from a central portion towards the opposite ends of the sleeve. Swaging collars with a tapered inner surface complementarily engage the tapered surface of the sleeve. As the collars are urged towards the central portion of the sleeve, the sleeve is deformed inwardly and the tube is deformed into mating relationship with the grooves and lands. An effective sealing union is achieved with only the sleeve and swage collars. Preferably, the collars and sleeve are swaged with a tool formed by two housings, each having two components. The two components of each housing are longitudinally axially separable and are arranged for threaded interengagement with each other. As interengagement increases, so the swage collars are urged towards each other, namely towards the central portion of the sleeve. Preferably, pins interact with each component of at least one housing member. Removal of the pins permits separation of the components of each housing member. By the construction, a lightweight union assembly is achieved for coupling ends of a pair of thin walled tubes or a tube and a tubular fitting. Typically, such parts are of lightweight high-strength material for use in the aircraft industry where high pressure hydraulic systems operate at between 20682 - 41364 kPa (3,000 - 6,000 psi) in the tube lines. The tubular fitting may be in the form of an elbow or other component which can have two right angularly directed longitudinal tubular portions. One limb of the elbow can be considered as one pipe end which is connected into the face end of an abutting tube end. The invention is further described with reference to the accompanying drawings, in which:- FIGURE 1 is an axial exploded view of a tube union with individual parts of the assembly in relationship with tubes; FIGURE 2 is an axial cross-section illustrating the two components of each housing member in unassembled relationship; FIGURE 3 is an axial cross-section of Figure 2 after the tube union is tightened with swage collars in abutting relationship within the sleeve; FIGURE 4 is an end view of the union illustrating the pins for effecting interengagement of the component part of one housing member; FIGURE 5 is a diagrammatic axial view illustrating the sealing connection of two elements which can be selectively separated; and FIGURE 6 is a diagrammatic axial view illustrating the sealing connection of two elements, at least one of which constitutes parts of an elbow configuration or shape. Referring to the drawings, a tube union assembly for coupling the ends of a pair of thin walled tubes constructed of lightweight, high-strength material, such as used in the aircraft industry, comprises a sleeve 10 positioned centrally over ends 11 and 12 of tubes 13 and 14 respectively. The ends 11 and 12 are in abutting relationship or close proximity and in effective nesting engagement. The tubes are of a titanium alloy, corrosion resistant steel, or aluminium alloy of the nature to withstand several thousands psi of hydraulic pressure. The sleeve 10 includes several circumferential lands 15 and spaced grooves 16. The lands 15 have a longitudinal length shorter than the longitudinal length of the grooves 16. The end lands 17, namely adjacent the extremities of the sleeve 10, have a longitudinal length substantially equal to the longitudinal length of the grooves 16. The depth of the grooves 16 is substantially less than the length of the grooves 16. The depth is substantially equal to the longitudinal length of the lands 15. The interface between the lands and grooves is substantially right angular so as to form teeth-like formations as viewed in cross section. The external surface 18 of the sleeve 10 has a central portion 19 of enlarged diameter. A pair of tapered external surfaces 119 and 20 have decreasing diameter from the maximum near the central portion 19 to a minium diameter near the opposite ends 21 and 22 of the sleeve 10. Between the central portion 19 and the maximum height of the tapered portion are circumferential slots 23 which abut the central portion 19. The maximum hight 24 of the tapered portions constitutes circumferential lips about the sleeve 10. Two swaging collars 25 are positioned in an abutting relationship with the sleeve 10. The collars 25 have a tapered inner surface 26 for complementary engagement with the tapered surfaces 119 and 20 of the sleeve 10. Around the periphery of the end of the collars 25 intended for location towards the central portion 19, there is provided a ring 27 and a circumferential slot 28. The slot 28 is accommodated in the circumferential lip of the sleeve 10. At the opposite end of each of the collars 25, namely the ends remote from the central portion 19, there is a circumferential slot 29. The collars 25 are forced onto the sleeve 10 such that the lips interengage with the slot 28. A firm and positive location is then achieved between the sleeve 10 and the collars 25. An effective seal is thus achieved between ends 11 and 12 of tubes 13 and 14 and the inside surface of the sleeve 10. As the collars 25 are drawn towards the central portion 19, the sleeve is radially compressed inwardly to deform both the inner and outer surfaces of the walls of the tubes 13 and 14. This bending action caused by the lands 15 of the sleeve 10 reduces the diameter of the walls of the tubes 13 and 14 adjacent the lands 15 by an equal amount. This is in the order of the thickness of the walls of the tubes 13 and 14. The tubes are bent outwardly into the regions occupied by grooves 16 such that the tubes 13 and 14 are formed into a series of ring joints involving indentations and convolutions corresponding to the lands 15 and grooves 16. This effects a permanent union of the tube ends 11 and 12. This union of the tube ends 11 and 12 is such that the internal pressure within the tubes 13 and 14 aids in tightening and securing the joints within the grooves 16 to enhance the tensile property of the joint. As such, there are only the three components necessary which form an effective union assembly. The swaging collars 25 are drawn towards the central portion 19 of the sleeve 10 by means of a swaging tool formed by a housing construction. The housing construction is formed of a first housing 30 which is constructed by two interlocking components and a second housing 39 also formed of two interlocking components. The housing 30 entirely surrounds the central portion 19 of the sleeve 10, and has internal threads 31 at one longitudinal end and an internal shoulder 32 at the opposite end 33. The housing additionally provides an external wrenching surface 34. Along a longitudinal line parallel to the axis of the tubes and the axis of the sleeve and the collars, there is provided in diametrically opposite positions tooth formations 35 and 36 respectively. With a wrench tool on the wrenching surface 34, the two components 37 and 38 making up the housing 30 are held in interengaging position and are non-separable. The tooth formations 35 and 36 are finely and carefully tooled for close tolerances and interengaging and interlocking location. In a different construction, pin elements can be used for longitudinal engagement parallel to the line of division so that the two components 37 and 38 can be anchored together. The second housing 39 also includes two components 40 and 41 which are split similarly along diametrically opposite longitudinal lines to form tooth surfaces 42 and 43. The second housing 39 has an externally threaded surface 44 for engagement with the internal threads 31 of the first housing 30. There is also an abutting face 45 for engagement with the ends of the collar 25. Pin elements 47 are directed longitudinally parallel to the axis to secure the components 40 and 41 in interengagement. Instead of the pin formation, a suitable tooth formation could be used to secure the two components 40 and 41 together. When the two housings 30 and 39 are drawn together by applying torsional forces to the wrenching surfaces, the collars 25 are drawn inwardly to the central position 19 of the sleeve 10 to the point that the leading lips of the collars 25 interengage with the lips on the sleeve 10. Interengagement effects a secure binding and locking of the sleeve 10 with the swaging collar 25. After this interengagement, the housings 30 and 39 can be removed by separation of the component parts. Only three components of the union assembly remain. By this construction a lightweight union assembly is provided with a minimum of components while still achieving effective sealing force between the union assembly components and the tubes 13 and 14. Removal of the wrenching tool from the housing 30 permits for separation of the housing 30 into its component parts. Thereafter the removal of the pins 47 from the components of the second housing 39 is easily achieved. This permits separation of the housings 30 and 39 from the three components constituting the union assembly. The union assembly can be used for repairing broken hydraulic tubing where the only tools required are two wrenches, one for each of the housings. The housings in their separable format can be re-used with different sleeves and swaging collars. In some formats it may be desirable to retain the housings 30 and 39 in position over the collars 25. In other cases, the housings 30 and 39 may be removable by means different from separation upon a longitudinal split line. For instance, the housings may simply be drawn axially off the tubes 13 and 14. In different formats the components of the housings 30 and 39 may be formed by more than two components for each housing. Although the groove and land formations have been illustrated as constituting a square tooth-like formation, it should be clear that different cross sections of teeth could be used. The cross sectional area of each groove and land can vary according to desired sealing formations and constructions. This may be dependent on the material of the tubing and the sleeve. The location of the lip relative to the land and groove and the tapered construction is such that interlocking of the swaging collars with the lip is effective. When the swaging collars cause the requisite degree of deformation of the sleeve 10, an effective biting seal is achieved between the outside wall of the tubes 13 and 14 with the lands and grooves. The construction has been illustrated with regard to a screw-together union assembly between sleeves and swaging collar. It is, however, possible that the components can be drawn together in the tapering interaction by a different formation thereby forming an assembly constituted by different removable housings 30 and 39. The effective seal for high pressure hydraulic lines is achieved by having the longitudinal length of each of the grooves several times the thickness of the walls of the tubes 13 and 14. In other constructions, different groove and land cross sections can be provided. Instead of housings 30 and 39 for forming the union, it is possible to provide a wedge tool which can be operable to effect the coupling action with hydraulic or other pressure as required. In Figure 5 there is illustrated diagrammatically the connection of tubing to a fitting which has a permanent and separable end. Elements 100 and 101 form a permanent connection using a tool having the two housings 30 and 39. The housings 30 and 39 have the same two components as described with reference to Figures 1 and 4, and operate similarly. Element 100 provides a shoulder 102 for the collar 103 of the component 30 to anchor against as the housings 30 and 39 are drawn together. When the element 101 is axially urged into the drawn up longitudinal position, lip 104 engages in the rim 105 and the two elements 100 and 101 are locked together in a sealing relationship as described with regard to figures 1 to 4. The housings 30 and 39 constituting the tool can then be removed. In this fashion the one element 100 is similar to a portion of sleeve 10 and the elements 101 is similar to one of the collars 25 of Figures 1 to 4. The components 100 and 101 can then be affixed to any other additional elements, as necessary. The additional elements may be selectively separable from elements 100 and 101 according to desired characteristics and applications. Element 100 can be hollow or solid as desired. In Figure 6 a different diagrammatic construction is shown. The same tool using housings 30 and 39 is applied as earlier described with reference to Figures 1 to 5. Housing 30 co-operates with a shoulder 102 of an elbow element 106, which is a first element. A second element, namely tube 107 is secured to the inside surface of the tubular limb 108 of the element 106. The limb 108 is part of the first element 106. The element 106 and limb 108 constitute at least part of the sleeve 10 of the embodiment of Figures 1 to 4. Bringing together of the housings 30 and 39 effects tool operation so that deformed rings are formed to achieve a swaged connection of tube 107 with the elbow element 106. In different connections, instead of an elbow element 106, different shapes and configurations having different longitudinal or angular relationships to each other can be provided. The limb 109 of the elbow element is right angularly directed relative to tube 107. In this illustrative embodiment collar 110 is activated by the tool similar to one of the collars 25 of the construction of Figures 1 to 4. Different constructions and shapes are possible. For instance, instead of the elbow element, the component may be a T-piece or Y-piece. Thus different numbers of tubes can be secured to the fitting. Many other examples of the invention exist, each different from the others in matters of detail only. The scope of the invention is to be determined solely by the following claims. In our co-pending European Application No.91904450.3 there are claims directed to apparatus for making a union assembly and method of forming the same.

Claims: A fluid tight union assembly comprising the end of a tube (14 or 107), a first end portion of a sleeve (10 or 100) and a collar (25 or 101), the first end portion of the sleeve (10 or 100) being concentrically disposed around the end of the tube (14 or 107) and the collar (25 or 101) being concentrically disposed around the first end portion of the sleeve (10 or 100), wherein the external surface of the end of the tube (14 or 107) has a series of spaced ring joints, the first end portion of the sleeve (10 or 100) has an internal surface with a series of spaced circumferential lands (15) which are engaged in the ring joints, and the first end portion of the sleeve (10 or 100) has an external surface with a tapered external face (20) which decreases in diameter towards a first end of the sleeve (10 or 100), the union assembly being characterised by a raised lip (24) on the external surface of the sleeve (10 or 100) which is engaged by a ring (27) and a slot (28) on the internal surface of the collar (25 or 101) firmly to retain the collar (25 or 101) on the sleeve (10 or 100). A union assembly as claimed in claim 1, wherein the sleeve has an internal surface with a spaced series of circumferential lands (15) and grooves (16), and wherein, when the sleeve (10 or 100) engages the external wall of the tube, the wall of the tube (14 or 107) is deformed into engagement in the grooves (16) between the lands (15) such that the tube (14 or 107) forms a series of ring joints corresponding to the lands (15) and grooves (16). A union assembly as claimed in claim 2, wherein there are at least two grooves (16) for the tube end, and wherein the length of each groove (16) is longer than the length of each land (15) between the grooves (16). A union assembly as claimed in claim 1, 2 or 3, and which couples the ends of two tubes (13,14) wherein the sleeve (10) further comprises a second end portion (21) opposite the first end portion (22), a central portion (19) between the end portions (21, 22) and a second tapered surface (119) on the external face of the second end portion (21) of the sleeve, wherein the first and second tapered surfaces (119, 20) decrease in diameter from the central portion (19) towards the first and second end portions (21, 22) of the sleeve respectively, the sleeve being positioned centrally over butting ends of the two tubes (13, 14), and further comprising a second collar (25) concentrically positioned around the second end portion (21) of the sleeve (10), each collar (25) having been urged axially towards the central portion (19) of the sleeve (10), whereby the sleeve (10) has been compressed inwardly and the walls of the tubes (13, 14) have been deformed into engagement with grooves (16) between lands (15) on the internal surface of each end portion (21) of the sleeve, such that the tubes (13, 14) form a series of ring joints corresponding to the lands (15) and grooves (16), and wherein the external surface of the second end portion (21) of the sleeve (10) includes a second raised lip (24), and wherein the first mentioned and second raised lips (24) are spaced respectively from the central portion (19) of the sleeve (10), the second collar (25) including a ring (27) and a slot (28) in its internal surface (26), the ring (27) and the slot (28) in the second collar (25) accommodating the second raised lip (24) in the sleeve (10), firmly to retain the second collar, and wherein the coupling is effective to withstand substantial pressures. A union assembly as claimed in claim 4, wherein the first and second tapered surfaces (119, 20) extending inwardly from each end of the sleeve terminate in the first and second raised lips (24) respectively, and wherein an indented circular slot (23) is provided between each lip (24) and the central portion (19). A union assembly as claimed in either claim 4 or 5, wherein there are at least two grooves (16) in the internal surface of the sleeve (10) for each tube end (11, 12), and wherein the length of each groove (16) is longer than the length of each land (15) between the grooves (16). A union assembly as claimed in claim 6, wherein each end of the sleeve has a land (17) with a length substantially equal to the length of each groove (16). A union assembly as claimed in any one of claims 4-7, wherein the tapered external surfaces (119, 20) decrease generally smoothly in diameter from the central portion (19) of the sleeve (10) towards opposite ends of the sleeve (10), and wherein each collar (25) is located in adjacent relationship with a respective end of the sleeve (10), each collar (25) being non-engaging of the other collar. A union assembly as claimed in any one of the preceding claims, wherein the thickness about the slot in the or each collar is less than the thickness remote from the slot. A method for forming a fluid tight connection between the end of a tube (14 or 107) and a first end portion of a sleeve (20 or 100), wherein the sleeve (10 or 100) is concentrically disposed in abutting relationship around the end of the tube (14 or 107), the first end portion of the sleeve (10 or 100) has an internal surface with a series of spaced circumferential lands (15), and the first end portion of the sleeve (10 or 100) has an external surface with a tapered external face (20) which decreases in diameter towards a first end of the sleeve (10 or 100), the method comprising the steps of positioning the first end portion of the sleeve (10 or 100) over the end of the tube (14 or 107), positioning a swaging collar (25 or 101) concentrically and in abutting relationship over the first end portion of the sleeve (10 or 100), and urging the collar (25 or 101) axially towards the centre of the sleeve (10 or 100) so that the tube (14 or 107) is compressed inwardly by the lands (15) on the internal surface of the sleeve (10 or 100), thereby deforming the wall of the tube (14 or 107) and forming a series of spaced ring joints on the external surface of the tube (14 or 107) which engage the lands (15), the method being characterised by the external surface of the sleeve (10 or 100) having a raised lip (24) and the internal surface of the collar (25 or 101) having both a ring (27) and a slot (28), such that, after the collar (25 or 101) is urged axially toward the centre of the sleeve (10 or 100) and a fluid tight connection is formed between the end of the tube (14 or 107) and the sleeve (10 or 100), the lip (24) on the sleeve (10 or 100) is engaged by the ring (27) and the slot (28) on the collar (25 or 101) firmly to retain the collar (25 or 101) on the sleeve (10 or 100). A method as claimed in claim 10 for coupling the ends of two tubes (13,14), the sleeve (10) further comprising an internal surface with grooves (16) within each end portion of the sleeve, a central portion (19) between the two ends (21,22) of the sleeve, and a second external tapered surface (119) on a second end portion of the sleeve (10), wherein the tapered surfaces (18, 119) decrease in diameter from the central portion (19) of the sleeve (10) towards the opposite ends (21,22) of the sleeve (10), and wherein the central portion (19) of the sleeve is positioned centrally over butting ends (11,12) of the tubes (13,14), the method comprising the additional steps of positioning a second swaging collar (25) in an engaging relationship with the second end portion (21) of the sleeve (10), urging each respective collar (25) axially towards the central portion (19) of the sleeve (10), and compressing the sleeve (10) inwardly to deform the wall of the tubes (13,14) into engagement in the grooves (16) on the sleeve, wherein at the second end portion of the sleeve the external surface of the sleeve (10) comprises a second raised lip (24), the first and second lips (24) being spaced from the central portion (19) of the sleeve (10), including the step of engaging each respective collar (25) with slots (23) in the external surface of the sleeve (10) located between the respective lips (24) and the central portion (19), each collar (25) including a ring (27) and a slot (28) accommodating the lips (24) and the slots (23) in the sleeve, and wherein the coupling is effective to withstand substantial pressures. A method as claimed in claim 11, wherein the tapered portions (119, 18) extending inwards from each end of the sleeve (10) terminate in the respective raised lip (24) spaced from the central portion (19) of the sleeve (10), and wherein the slots (23) are circular and are provided between each lip (24) and the central portion (19), and including the step of urging each respective collar (25) into engagement with the lip (24).

Inventors: BINFORD JOHN L, HOSSEINIAN AMIR P, BINFORD, JOHN L., HOSSEINIAN, AMIR P.
Applicants: SIERRACIN CORP, SIERRACIN CORPORATION
Application year: 1991
Main classification: F16L13
IPC codes: F16L13, B25B27