Technique for joining tubular members

Abstract

In a technique for joining ends of coaxial tubular members, adhesive is applied to their external surfaces at their ends and an expandable insert assembly is positioned longitudinally within them so as to be coextensive with the adjoining ends. Planar side pieces on the assembly are advanced into conforming engagement with the inside surfaces of the tubular members at their adjoining ends, the adhesive is cured to fixedly join the tubular members together, then the side pieces are withdrawn. Simultaneously, the external surfaces of the tubular members are clamped in the region of their adjoining ends until full curing of the adhesive has been achieved. The insert assembly includes a bladder of flexible material with planar side pieces being attached to the inside or outside surfaces and the insert assembly advanced so the bladder engages the internal surfaces of the tubular members at their adjoining ends.

What is claimed is:  
     
         1 . A method of joining a pair of axially aligned opposed ends of first and second straight or curved tubular members having internal and external surfaces and being in an adjoining coaxial relationship, the method comprising the steps of: 
 (a) positioning an expandable insert assembly longitudinally of the first and second tubular members so as to be generally coextensive with the adjoining ends;    (b) from within the first and second tubular members, advancing the expandable insert assembly including a plurality of planar side pieces from a withdrawn position distant from the internal surfaces of the tubular members to be joined into an advanced position in conforming engagement with the inside surfaces of the tubular members in the region of their adjoining ends,    (c) applying adhesive to the first and second tubular members at the joint in the region of their adjoining ends;    (d) curing the adhesive to a fully bonded condition fixedly joining together the first and second tubular members;    (e) withdrawing the planar side pieces from their advanced positions to their withdrawn positions; and    (f) withdrawing the entire expandable insert assembly from within the bonded tubular members.    
     
     
         2 . The method as set forth in  claim 1   wherein the insert assembly includes a bladder of flexible material with an inside surface and an outside surface; and    wherein side pieces are attached to the inside surface of the insert assembly; and    wherein step (b) includes the step of: 
 (g) advancing the insert assembly so the bladder with the underlying attached side pieces engages the internal surfaces of the tubular members in the region of their adjoining ends.  
   
     
     
         3 . The method as set forth in  claim 1   wherein the insert assembly includes a bladder with an inside surface and an outside surface; and    wherein side pieces are attached to the outside surface of the insert assembly; and    wherein step (b) includes the step of: 
 (g) advancing the insert assembly so the side pieces engage the internal surfaces of the tubular members in the region of their adjoining ends.  
   
     
     
         4 . The method as set forth in  claim 3   wherein the bladder has parallel opposed spaced apart major portions and parallel opposed spaced apart minor portions and has corner edges at the intersections of adjoining major portions and minor portions.    
     
     
         5 . The method as set forth in  claim 2  including the steps of: 
 (h) forming the first and second tubular members so as to be of rectangular cross section including parallel spaced apart major side walls and parallel spaced apart minor side walls lying in planes perpendicular to the major side walls; and  
 wherein step (g) includes the steps of: 
 (i) attaching major side pieces to the inside surface of the insert assembly at opposed locations;  
 (j) attaching minor side pieces to the inside surface of the insert assembly at opposed locations; and  
 (k) advancing the insert assembly so the bladder at the major side pieces engages the internal surfaces of the major side walls of the tubular members in the region of their adjoining ends and so the bladder at the minor side pieces engages the internal surfaces of the minor side walls of the tubular members in the region of their adjoining ends.  
 
 
     
     
         6 . The method as set forth in  claim 5   wherein the bladder has parallel opposed spaced apart major portions and parallel opposed spaced apart minor portions and has corner edges at the intersections of adjoining major portions and minor portions.    
     
     
         7 . The method as set forth in  claim 3  including the step of: 
 (h) forming the first and second tubular members so as to be of rectangular cross section including parallel spaced apart major side walls and parallel spaced apart minor side walls lying in planes perpendicular to the major side walls; and  
 wherein the bladder has parallel opposed spaced apart major portions and parallel opposed spaced apart minor portions and has corner edges at the intersections of adjoining major portions and minor portions; and  
 wherein step (g) includes the steps of: 
 (i) attaching four side pieces to the outside surface of the bladder member so as to be coextensive with each of the corner edges and adjoining parts of each associated major portion and minor portion; and  
 (j) advancing the insert assembly so the four side pieces engage the internal surfaces of the tubular members in the region of their adjoining ends.  
 
 
     
     
         8 . The method as set forth in  claim 5   wherein the side pieces have a generally rectangular cross section and have mating beveled surfaces on adjoining major and minor side pieces;    wherein the bladder is of stretchable material and defines an internal cavity; and    wherein step (a) includes the step of: 
 (l) introducing pressurized fluid into the cavity;  
   wherein step (e) includes the step of: 
 (m) exhausting the pressurized fluid from the cavity through an opened exhaust valve until the expandable insert assembly has withdrawn to its withdrawn position under the bias of the stretchable bladder.  
   
     
     
         9 . The method as set forth in  claim 8  including the step of: 
 (n) applying a vacuum source to the opened exhaust valve to assist in withdrawing the insert assembly to the withdrawn position.  
 
     
     
         10 . The method as set forth in  claim 5   wherein the side pieces have a generally rectangular cross section and have mating beveled surfaces on adjoining major and minor side pieces;    wherein the bladder is of stretchable material and defines an internal cavity; and    wherein step (b) includes the step of: 
 (l) introducing pressurized fluid into the cavity; and  
   wherein step (e) includes the step of 
 (m) exhausting fluid from the cavity until the expandable insert assembly has withdrawn to its withdrawn position under the bias of the stretchable bladder. A vacuum source may be applied to the opened exhaust valve to assist in withdrawing the insert assembly to the withdrawn position.  
   
     
     
         11 . The method as set forth in  claim 10  including the step of 
 (n) applying a vacuum source to the opened exhaust valve to assist in withdrawing the insert assembly to the withdrawn position.  
 
     
     
         12 . The method as set forth in  claim 2  including the step of 
 (h) forming the first and second tubular members so as to be of rectangular cross section including parallel spaced apart major side walls and parallel spaced apart minor side walls lying in planes perpendicular to the major side walls; and  
 wherein the bladder has parallel opposed spaced apart major portions and parallel opposed spaced apart minor portions and has corner edges at the intersections of adjoining major portions and minor portions;  
 wherein step (h) includes the steps of: 
 (i) attaching a pair of first major side pieces to the inside surface of the insert assembly;  
 (j) attaching a pair of second major side pieces to the outside surface of the insert assembly;  
 (k) joining the first and second major side pieces by a transverse fastener extending through the bladder;  
 (l) attaching a pair of first minor side pieces to the inside surface of the insert assembly;  
 (m) attaching a pair of second minor side pieces to the outside surface of the insert assembly;  
 (n) joining the first and second minor side pieces by a transverse fastener extending through the bladder; and  
 (o) advancing the insert assembly so the major side pieces attached to the outside surface of the insert assembly engage the internal surfaces of the major side walls of the tubular members in the region of their adjoining ends and so the minor side pieces attached to the outside surface of the insert assembly engage the internal surfaces of the minor side walls of the tubular members in the region of their adjoining ends.  
 
 
     
     
         13 . The method as set forth in  claim 1  including the step of: 
 (g) clamping the external surfaces of the first and second tubular members in the region of their adjoining ends until full curing of the adhesive has been achieved.  
 
     
     
         14 . A method of simultaneously joining a plurality of pairs of axially aligned opposed ends of first and second tubular members having internal and external surfaces and being in an adjoining coaxial relationship, the method comprising the steps of: 
 (a) providing an insert assembly at each location for joining a pair of the opposed ends of the first and second tubular members;    (b) providing a source of pressurized fluid;    (c) providing a conduit connecting in series each of the insert assemblies;    (d) at each location, providing an expandable insert assembly including a bladder defining an internal cavity with an inside surface and an outside surface and having a cross sectional configuration similar to that of the first and second tubular members and a plurality of planar side pieces attached to the inside surface or outside surface of the bladder;    (e) from within the first and second tubular members, introducing pressurized fluid from a source into the conduit to each insert assembly to advance the insert assembly from a withdrawn position distant from the internal surfaces of the tubular members to be joined into an advanced position in conforming engagement with the inside surfaces of the tubular members in the region of the their adjoining ends;    (f) applying adhesive to the external surfaces of the first and second tubular members in the region of their adjoining ends;    (g) curing the adhesive to a fully bonded condition fixedly joining together the first and second tubular members; and    (h) withdrawing the expandable insert assembly from its advanced position to its withdrawn position.    (i) withdrawing the entire expandable insert assembly from within the bonded tubular members.    
     
     
         15 . Apparatus for joining a pair of axially aligned opposed ends of first and second tubular members having internal and external surfaces and being in an adjoining coaxial relationship, adhesive subsequently being applied to the external surfaces of the tubular members in the region of their adjoining ends, the apparatus comprising: 
 an expandable insert assembly positioned longitudinally of the first and second tubular members so as to be generally coextensive with the adjoining ends, the insert assembly including a plurality of planar side pieces and being movable between withdrawn positions distant from the internal surfaces of the tubular members to be joined and advanced positions in conforming engagement with the inside surfaces of the tubular members in the region of their adjoining ends while the adhesive is cured to a fully bonded condition fixedly joining together the first and second tubular members after which the planar side pieces are withdrawn from their advanced positions to their withdrawn positions.    
     
     
         16 . Apparatus as set forth in  claim 15   wherein the insert assembly includes a bladder of flexible material with an inside surface and an outside surface; and    wherein the side pieces are attached to the inside surface of the insert assembly such that as the insert assembly is advanced to the advanced position, the bladder engages the internal surfaces of the tubular members in the region of their adjoining ends.    
     
     
         17 . Apparatus as set forth in  claim 15   wherein the insert assembly includes a bladder with an inside surface and an outside surface; and    wherein the side pieces are attached to the outside surface of the insert assembly such that as the insert assembly is advanced to the advanced position, the side pieces engage the internal surfaces of the tubular members in the region of their adjoining ends.    
     
     
         18 . Apparatus as set forth in  claim 17   wherein the bladder has parallel opposed spaced apart major portions and parallel opposed spaced apart minor portions and has corner edges at the intersections of adjoining major portions and minor portions.    
     
     
         19 . Apparatus as set forth in  claim 16   including the first and second tubular members being of rectangular cross section including parallel spaced apart major side walls and parallel spaced apart minor side walls lying in planes perpendicular to the major side walls;    major side pieces being attached to the inside surface of the insert assembly at opposed locations; and    minor side pieces being attached to the inside surface of the insert assembly at opposed locations;    such that as the insert assembly is advanced, the bladder at the major side pieces engages the internal surfaces of the major side walls of the tubular members in the region of their adjoining ends and such that the bladder at the minor side pieces engages the internal surfaces of the minor side walls of the tubular members in the region of their adjoining ends.    
     
     
         20 . Apparatus as set forth in  claim 19   wherein the bladder has parallel opposed spaced apart major portions and parallel opposed spaced apart minor portions and has corner edges at the intersections of adjoining major portions and minor portions.    
     
     
         21 . Apparatus as set forth in  claim 17   wherein the first and second tubular members are of rectangular cross section including parallel spaced apart major side walls and parallel spaced apart minor side walls lying in planes perpendicular to the major side walls;    wherein the bladder has parallel opposed spaced apart major portions and parallel opposed spaced apart minor portions and has corner edges at the intersections of adjoining major portions and minor portions; and    four side pieces being attached to the outside surface of the bladder member so as to be coextensive with each of the corner edges and adjoining parts of each associated major portion and minor portion such that as the insert assembly is advanced to the advanced position, the four side pieces engage the internal surfaces of the tubular members in the region of their adjoining ends.    
     
     
         22 . Apparatus as set forth in  claim 19  including: 
 a source of pressurized fluid;  
 wherein the side pieces have a generally rectangular cross section and have mating beveled surfaces on adjoining major and minor side pieces;  
 wherein the bladder is of stretchable material and defines an internal cavity; and  
 such that with the introduction of pressurized fluid into the cavity, the insert assembly is advanced until the bladder at the major side pieces engages the internal surfaces of the major side walls of the tubular members in the region of their adjoining ends and such that the bladder at the minor side pieces engages the internal surfaces of the minor side walls of the tubular members in the region of their adjoining ends and such that when the pressurized fluid is exhausted from the cavity, the expandable insert assembly is moved to its withdrawn position under the bias of the stretchable bladder.  
 
     
     
         23 . Apparatus as set forth in  claim 19   wherein the side pieces have a generally rectangular cross section and have mating beveled surfaces on adjoining major and minor side pieces;    wherein the bladder is of stretchable material and defines an internal cavity; and    including a source of pressurized fluid for introduction into the cavity to move the expandable insert assembly has to its advanced position and a source of vacuum for introduction into the cavity to evacuate fluid from the cavity until the expandable insert assembly has withdrawn to its withdrawn position.    
     
     
         24 . Apparatus for joining a plurality of successive longitudinally spaced pairs of axially aligned opposed ends of first and second tubular members having internal and external surfaces and being in an adjoining coaxial relationship, adhesive subsequently being applied to the external surfaces of the tubular members in the region of their adjoining ends, the apparatus comprising: 
 a plurality of successive longitudinally spaced expandable insert assemblies positioned longitudinally of the successive pairs of the first and second tubular members so as to be generally coextensive with the adjoining ends, each insert assembly including a plurality of planar side pieces and being movable between a withdrawn position distant from the internal surfaces of the tubular members to be joined and an advanced position in conforming engagement with the inside surfaces of the tubular members in the region of their adjoining ends while the adhesive is cured to a fully bonded condition fixedly joining together the first and second tubular members after which the planar side pieces are withdrawn from their advanced positions to their withdrawn positions.    
     
     
         25 . Apparatus as set forth in  claim 24   wherein each insert assembly includes a bladder of flexible material with an inside surface and an outside surface; and    wherein the side pieces are attached to the inside surface of each insert assembly such that as the insert assembly is advanced to the advanced position, the bladder engages the internal surfaces of the tubular members in the region of their adjoining ends.    
     
     
         26 . Apparatus as set forth in  claim 24   wherein each insert assembly includes a bladder with an inside surface and an outside surface; and    wherein the side pieces are attached to the outside surface of each insert assembly such that as the insert assembly is advanced to the advanced position, the side pieces engage the internal surfaces of the tubular members in the region of their adjoining ends.    
     
     
         27 . Apparatus as set forth in  claim 24   wherein each expandable insert assembly includes a bladder of flexible elastic material defining an internal cavity and biased toward the withdrawn position; and    including:    a source of pressurized fluid;    an inlet conduit extending between the source of pressurized fluid and a first of the expandable insert assemblies;    an inlet valve in the inlet conduit for selectively connecting the first of the expandable insert assemblies to the source of pressurized fluid;    an outlet conduit extending away from a last of the expandable insert assemblies;    an outlet valve in the outlet conduit for selectively connecting the last of the expandable insert assemblies to the surrounding atmosphere;    an intermediate conduit extending between each successive pair of the expandable insert assemblies; and    a one-way valve in each intermediate conduit permitting flow only in the direction of the inlet valve toward the outlet valve;    such that with opening of the inlet valve and closing of the outlet valve with resultant introduction of pressurized fluid into the cavity for each insert assembly, each insert assembly is advanced until the bladder at the planar side pieces engages the internal surfaces of the side walls of the tubular members in the region of their adjoining ends and such that with closing of the inlet valve and opening of the outlet valve with resultant depressurization of the fluid into the surrounding atmosphere, each expandable insert assembly is moved to its withdrawn position under the bias of the stretchable bladder.    
     
     
         28 . A method of simultaneously joining a first pair of axially aligned opposed ends of a first tubular member and of a second tubular member and a second pair of axially aligned opposed ends of the second tubular member and of a third tubular member, the tubular members having internal and external surfaces and being in an adjoining coaxial relationship, the second tubular member having a curved longitudinal axis defining a bend region, the method comprising the steps of: 
 (a) providing a plurality of serially connected expandable insert assemblies, each insert assembly including a bladder with an inside surface and an outside surface and planar side pieces attached to the outside surface of the bladder;    (b) drawing the serially connected expandable insert assemblies longitudinally of the first and second tubular members and of the second and third tubular members until a insert assembly is generally coextensive with the adjoining ends of the first and second tubular members and of the second and third tubular members, respectively;    (c) from within the first and second tubular members, advancing the expandable insert assembly including the plurality of planar side pieces from a withdrawn position distant from the internal surfaces of the tubular members to be joined into an advanced position in conforming engagement with the inside surfaces of the tubular members in the region of their adjoining ends;    (d) applying adhesive to the external surfaces of the first and second tubular members and of the second and third tubular members in the regions of their adjoining ends;    (e) curing the adhesive to a fully bonded condition fixedly joining together the first and second tubular members;    (f) withdrawing the planar side pieces from their advanced positions to their withdrawn positions; and    (g) withdrawing the entire expandable insert assembly from within the bonded tubular members.    
     
     
         29 . The method as set forth in  claim 28  including the steps of: 
 (h) forming the first, second, and third tubular members so as to be of rectangular cross section including parallel spaced apart major side walls and parallel spaced apart minor side walls lying in planes perpendicular to the major side walls;  
 (i) attaching major side pieces to the inside surface of the insert assembly at opposed locations;  
 (j) attaching minor side pieces to the inside surface of the insert assembly at opposed locations; and  
 (k) advancing the insert assembly so the bladder at the major side pieces engages the internal surfaces of the major side walls of the tubular members in the region of their adjoining ends and so the bladder at the minor side pieces engages the internal surfaces of the minor side walls of the tubular members in the region of their adjoining ends.  
 
     
     
         30 . The method as set forth in  claim 29   wherein the side pieces have a generally rectangular cross section and have mating beveled surfaces on adjoining major and minor side pieces;    wherein the bladder is of stretchable material and defines an internal cavity; and    such that as the serially connected expandable insert assemblies are drawn longitudinally of the first and second tubular members and of the second and third tubular members through the bend region, the major and minor side pieces are caused to contract toward one another until their mating beveled surfaces come into engagement enabling free passage through the bend region.    
     
     
         31 . The method as set forth in  claim 30   wherein step (d) includes the step of: 
 (l) introducing pressurized fluid into the cavity; and  
   wherein step (f) includes the step of: 
 (m) exhausting the pressurized fluid from the cavity through an opened exhaust valve until the expandable insert assembly has withdrawn to its withdrawn position under the bias of the stretchable bladder. A vacuum source may be applied to the opened exhaust valve to assist in withdrawing the insert assembly to the withdrawn position.  
   
     
     
         32 . The method as set forth in  claim 31  including the step of 
 (n) applying a vacuum source to the opened exhaust valve to assist in withdrawing the insert assembly to the withdrawn position.  
 
     
     
         33 . Apparatus for joining a plurality of successive longitudinally spaced pairs of axially aligned opposed ends of first and second tubular members having internal and external surfaces and being in an adjoining coaxial relationship, adhesive having been applied to the external surfaces of the tubular members in the region of their adjoining ends, the apparatus comprising: 
 a plurality of successive longitudinally spaced expandable insert assemblies positioned longitudinally of the successive pairs of the first and second tubular members so as to be generally coextensive with the adjoining ends, each insert assembly including a plurality of planar side pieces and being movable between a withdrawn position distant from the internal surfaces of the tubular members to be joined and an advanced position in conforming engagement with the inside surfaces of the tubular members in the region of their adjoining ends while the adhesive is cured to a fully bonded condition fixedly joining together the first and second tubular members after which the planar side pieces are withdrawn from their advanced positions to their withdrawn positions.    
     
     
         34 . The method as set forth in  claim 1  including the steps, before step (a) of: 
 (g) forming a socket at the end of the second tubular member to conformingly receive the end of the first tubular member; and  
 wherein step (c) includes the step of: 
 (h) applying adhesive to the socket formed in step (g).  
 
 
     
     
         35 . Apparatus as set forth in  claim 15   wherein the end of the second tubular member is formed as a socket to conformingly receive the end of the first tubular member; and    wherein the adhesive is applied to the socket between the ends of the first and second tubular members.