Abstract:
There is provided a process that includes providing an extruded fitting having a bore formed therein. The bore is machined from one or both sides of the extruded fitting to provide a ledge on one side for interacting with a corresponding fitting and a stop on the other. A pipe and braze sleeve are placed in combination into the bore and engage the stop. The pipe and bore include anti-rotation and location irregularities formed thereon to maintain a desired orientation of the parts. A mandrel is used to deform the pipe and sleeve to the shape of the bore. The parts are then brazed in a furnace.

Description:
TECHNICAL FIELD 
     This invention generally relates to a process for attaching fittings to pipes prior to a brazing operation. With more particularity, this invention relates to the process for attaching fittings to pipes wherein an extruded fitting is machined from opposite sides to allow for inter-engagement with a corresponding fitting on one side and a pipe on the other. 
     BACKGROUND OF THE INVENTION 
     Heat exchangers, radiators, evaporators, and condensers are typically manufactured from an alloy that is coated or clad with a thin surface layer of braze material which is then cycled through a braze oven to permanently join the parts together. It is common for pipes to be joined with such parts as, a condenser core utilizing the same braze oven that is used to braze the condenser core. The fittings and pipes are commonly provided, pre-brazed to each other as a pipe and block fitting assembly, by an outside supplier to be used as a component of the larger assembly, such as a condenser unit. It has been found that the originally formed joint between a pipe and a fitting will remelt and solidify, during the condenser core brazing operation. Problems can occur when the brazing alloy flows away from where it was intended and solidifies with less overlapping surface than is ideally desired. This less than desirable braze overlap is often of sufficient strength for the joint to successfully pass a quality check to detect leaks, but the weakened joint may then fail during the installation or attachment process in an assembly plant. It has been suggested to use a higher temperature braze alloy for the pipe to fitting attachment that would tend not to remelt during the condenser brazing operation. However, the fitting materials that are used for their desirable machining properties have a melting temperature that would be close in temperature to the higher melting temperature brazing alloys. Therefore, use of the higher melting temperature brazing alloys is not desirable, as it may cause the fitting itself to melt and lose its integrity during pipe to fitting attachment, prior to passing the pipes through the condenser brazing operation. 
     Accordingly, it is an object of the present invention to provide a method for maintaining the orientation of fittings to pipes without brazing them prior to a core brazing operation, to provide a geometry in which a strong braze overlap of the pipe to fitting is created in the final assembly braze process, such as the condenser core braze operation, while joint re-melt or deterioration is avoided. It is also an object of the present invention to provide a method of brazing fittings to pipes such that the orientation of the fitting and pipes can be maintained without the use of complicated brazing fixtures. 
     SUMMARY OF THE INVENTION 
     There is provided a process which cures those deficiencies outlined above and provides a reliable means to assure a quality fitting to pipe joint, as well as maintain the proper orientation of the parts. The process includes providing an extruded fitting which has a bore formed by the extrusion process extending from a first surface to a second surface, where the axis of the bore is approximately perpendicular to both of the first and second surfaces. The bore is then machined in both directions along the axis of the bore. The bore is machined from the first surface along the axis to form a ledge that will interact with a corresponding fitting. The bore is machined from a direction from the second surface along the axis for a distance that is less than the entire length of the bore, to provide a stop. A pipe having a braze collar placed circumferentially thereon is then inserted into the extruded fitting in a direction from the second surface to inter-engage the collar and the stop. The pipe and collar is then expanded using a mandrel to conform the shape of the pipe and collar to the bore. The assembled fitting is then brazed in a furnace to permanently attach the pipe to the extruded fitting. 
    
    
     BRIEF DESCRIPITION OF THE DRAWINGS 
     The various advantages of the present invention will become apparent to one skilled in the art by reading the following specification and claims and by referencing the following drawings in which: 
     FIG. 1 is a plan view of the fitting and pipe; 
     FIG. 2 is a sectional view of the fitting and pipe; 
     FIG. 3 is a side view of the fitting and pipe; 
     FIG. 4 is a sectional view of the fitting and pipe; 
     FIG. 5 is a sectional view of the fitting and pipe; 
     FIG. 6 is a environmental view showing the fitting and pipe in relation to a condenser core and a mating block fitting; 
     FIG. 7 is an assembly diagram detailing the various steps of the process; 
     FIG. 8 is a sectional view of an alternative embodiment of the fitting and pipe; and 
     FIG. 9 is an assembly diagram of an alternative embodiment detailing the various steps of the process. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 2, there is shown an assembled pipe and block fitting assembly  2  for use on an air conditioning condenser. The fitting assembly  2  has two major components: an extruded/machined fitting  5 , and a pipe  10 . The fitting  5  has a bore  15  formed therein extending from a first surface  25  to a second surface  20  approximately perpendicular to the first and second surfaces. As best seen in FIGS. 1 and 5, the bore has an irregularity  55  extruded therein to provide an anti-rotation and location feature. The irregularity as shown in FIG. 5 is a flattened area on an otherwise circular bore. It is to be understood that other irregularities, such as multi-faceted surfaces may also be used by the present invention without departing from the inventive aspect of the device. 
     The extruded fitting  5 , as shown in FIGS.  1 — 6 , has a second bore  17  formed therein for mating with a corresponding fitting  60 , as shown in FIG.  6 . The second bore  17  may receive a threaded stud  19  on which the corresponding fitting  60  may be secured. The second bore  17  may or may not be included with the extruded fitting  5  of the present invention. 
     In a preferred embodiment and with reference to FIG. 2, the extruded fitting  5  is machined in a direction along the axis of the bore  15  from both the first and second surfaces  25  and  20  respectively. As can be seen, the machined area from the direction of the first surface  25  forms a ledge  27  that interacts with a corresponding fitting  60  as can be seen in FIG.  6 . There may also be included a seal washer (not shown) that sits on the ledge  27  and interacts with ledge  27  and the corresponding fitting  60  to provide a seal. The extruded fitting  5  is also machined in a direction from the second surface  20  along the axis of the bore  15  for a distance less than the entire length of the bore  15  to provide a stop  35 . 
     In an alternative embodiment and with reference to FIG. 9, the extruded fitting  5  is machined in a direction along the axis of the bore  15  from the first surface  25 . The fitting  5  is not machined from a second direction. As with the preferred embodiment, the machined area from the direction of the first surface  25  forms a ledge  27  that interacts with a corresponding fitting  60 . There may also be included a seal washer (not shown) that sits on the ledge  27  and interacts with ledge  27  and the corresponding fitting  60  to provide a seal. 
     With reference to FIGS. 2 and 3, in a first embodiment the pipe  10  has a necked portion  45  over which a braze sleeve  40  is placed circumferentially around. The necked portion  45  provides a means for locating the braze sleeve  40  around the pipe  10  and allows for insertion of the pipe  10  into the fitting  5 . 
     In an alternative embodiment, shown in FIG. 8, a bead or skive may be utilized by the present invention to locate the braze sleeve  40  on the pipe  10 . 
     In a preferred embodiment, the pipe  10 , as best shown in FIG. 1, has a corresponding irregularity  50  formed thereon to interact with the irregularity  55  extruded on the bore  15  of the extruded fitting  5 . As the pipe  10  and extruded fitting  5  are mated, the irregularity  55  on the bore  15  and the irregularity  50  on the pipe  10  interact to provide an anti-rotation and location feature. 
     In an alternative embodiment, the pipe  10  would not have an irregularity  50  formed thereon. The pipe  10  would have a diameter sized such that it would be capable of insertion into the extruded fitting  5  past the irregularity  55 . In a step to be further described below, the mandrel  70  would then expand the pipe  10  into the irregularity  55 , thereby locking the orientation of the components. 
     The braze sleeve  40  may be a solid clad material, meaning the braze sleeve comprises a solid braze alloy material. Preferably, the braze sleeve comprises a layered clad material. With this orientation the layered clad material would comprise a clad material placed over a base material wherein the clad material is on both the interior surface  42  of the braze sleeve that corresponds to the pipe  10  as well as the exterior surface  44  which interacts with the extruded fitting  5 . Such an orientation of layered clad material would place the brazed material over a large contact area without relying upon capillary action. The layered clad material would also provide tight braze tolerances over a large area, whereas applying plain clad material over a comparable area, in such a way as to be maintained over that area through the braze process, would be more difficult. 
     In a preferred embodiment and with reference to FIGS. 7A, B, and C there is shown the process for assembling fittings to pipes of the preferred embodiment of the present invention. As can be seen in step A 1  the extruded fitting  5  is formed having a bore  15  formed therein including an irregularity  55 . With reference to step A 2  the extruded fitting  5  is machined from both the first surface  25  and second surface  20  to provide both a stop  35  for the pipe and a ledge  27  to mate with a corresponding fitting  60 . With reference to step B 1  and B 2  the pipe  10  is necked down and the irregularity  50  is added to provide the location and anti-rotation feature. With reference to step B 3 , the braze sleeve  40  is placed over the pipe  10  and is located by the necked down portion  45 . With reference to Steps AB 1  and AB 2 , the pipe  10  is then inserted into the extruded fitting  5  where it interacts with the stop  35  formed by the machining process from the second surface  25 . The sleeve  40  and stop  35  interact to provide a location for the depth of insertion of the pipe. Again, both the extruded fitting  5  and pipe  10  have irregularities  55 ,  50  respectively formed thereon that correspond so that the pipe  10  and extruded fitting  5  are held in a loose fit until a mandrel  70  (see step C 1  below) expands the pipe  10  into the fitting  5 . This design allows for the insertion of the pipe  10  in a manner to provide a means for maintaining a desired orientation of the pipe  10  and the extruded fitting  5 . With reference to FIG.  7 C and step C 1 , after the pipe  10  has been inserted into the extruded fitting  5  a mandrel  70  is used to deform the pipe  10  and sleeve  40  to the shape of the bore  15  formed within the extruded fitting  5 . With reference to step C 2 , the pipe  10  and sleeve  40  after being deformed are positively located in the extruded fitting  5  and may be brazed with a condenser core  65 , as depicted in FIG.  6 . The pipe  10  and extruded fitting  5  may be brazed in a braze furnace without the use of complicated fixtures. 
     In an alternative embodiment and with reference to FIGS. 9A, B and C, there is shown the process for assembling fittings to pipes of the alternative embodiment of the present invention. As can be seen in step A 1  the extruded fitting  5  is formed having a bore  15  formed therein including an irregularity  55 . With reference to step A 2  the extruded fitting  5  is machined from the first surface  25  to provide a ledge  27  to mate with a corresponding fitting  60 . With reference to step B 1  and B 2  the pipe  10  is necked down and the irregularity  50  is added to provide the location and anti-rotation feature. With reference to Step AB 1 , the pipe  10  is then inserted into the extruded fitting  5 . Again, both the extruded fitting  5  and pipe  10  have irregularities  55 ,  50  respectively formed thereon that correspond so that the pipe  10  and extruded fitting  5  are held in a loose fit until a mandrel  70  (see step C 1  below) expands the pipe  10  into the fitting  5 . This design allows for the insertion of the pipe  10  in a manner to provide a means for maintaining a desired orientation of the pipe  10  and the extruded fitting  5 . With reference to step AB 2 , the braze sleeve  40  is then placed over the pipe  10  from a direction of the first surface  25  and is located by the necked down portion  45 . With reference to FIG.  9 C and step C 1 , after the pipe  10  has been inserted into the extruded fitting  5  and the braze sleeve  40  has been placed circumferentially around the pipe  10 , a mandrel  70  is used to deform the pipe  10  and sleeve  40  to the shape of the bore  15  formed within the extruded fitting  5 . With reference to step C 2 , the pipe  10  and sleeve  40  after being deformed are positively located in the extruded fitting  5  and may be brazed with a condenser core  65 , as depicted in FIG.  6 . 
     While a preferred embodiment is disclosed, a worker in this art would understand the various modifications that come within the scope of the invention. Thus, the following claims should be studied to determine the true scope and content of this invention.