Abstract:
An improved crimp joint for joining components of gas or fluid distribution systems is disclosed. The joint is particularly suited for use with components made from low ductility materials including die cast metals. The joint comprises a flange formed by a first joined component and a second component that defines a second mating surface and a lip that is configured to closely surround at least a portion of the flange when the flange is positioned adjacent to the second mating surface. The joint is formed by deforming the lip to overlie the flange, capturing the flange between the deformed lip and the second mating surface. The flange includes a bead formed near the periphery of the flange on a surface against which the lip is deformed to abut to form the crimp joint. The bead is sized to deform and engage the lip thereby increasing the strength of the crimp joint.

Description:
FIELD OF THE INVENTION 
     This invention relates to an improved connection between pressure containing components of a fluid or gas system device, and in particular to a crimp joint that joins and secures components to each other and that has increased strength compared to prior crimp joints. The crimp joint comprises a flange extending from a first component and a cavity of a second component that accepts and closely surrounds the flange. The flange is defined by a flange mating surface and an engaging surface that face in generally opposite directions and extend from the first component to an outer flange edge. The cavity of the second component is defined by a second mating surface that is configured to conform to the flange mating surface and a lip that extends from the second mating surface to closely surround the outer flange edge. The lip extends from the second mating surface a distance that is greater than the width of the flange between the flange mating surface and the engaging surface. The crimp joint is formed by first positioning the flange within the cavity with the flange mating surface adjacent to the second mating surface. The lip is deformed toward the flange to overlie and conform to the engaging surface capturing the flange between the second mating surface and the deformed lip overlying the flange. The engaging surface of the flange is configured to abut the lip to prevent deformation of the lip to an extent that would weaken the lip and is configured to deform and to deform and engage the lip to provide a crimped joint of increased strength compared to prior crimp joints. 
     BACKGROUND OF THE INVENTION 
     Fluids and gas are distributed through systems of pipes or tubing that include pumps, valves, regulators, and other devices that control and direct movement of a fluid or gas through the system. In addition to performing their specific function within the distribution system, these devices must contain the fluid or gas within the device without leakage. 
     Devices used in fluid and gas distribution systems have varying degrees of mechanical complexity that depend on the system within which they are used and on their functions within the system. Most such components have internal components that cannot be reasonably assembled within the small space that they occupy in their assembled and functioning configuration. Manufacturing considerations require that the exterior of these devices be formed from separate, outer components that are joined to each other after the internal components are assembled and mounted to these outer components. The outer components of such devices generally form a barrier between the fluid or gas with in the system and the environment surrounding the system. The joints between outer components must be both strong and leak-proof. 
     One measure of the strength of the joint between outer components of a fluid or gas distribution system device is the amount of pressure within the device that can be contained without either leaking through the joint or failure of the joint. In addition to securing outer components to each other in a leak-proof manner, the joint between outer components may also be required to engage and support internal components of the device. 
     Different joints have been used to join outer components of fluid or gas distribution system devices depending on the requirements of the joint. Bolted joints are commonly used to provide a joint that has high strength and is leak-proof. Bolted joints are typically formed by two flanges, each joined component forming one of the flanges, that are configured to conform to each other along mating surfaces that are positioned adjacent to each other. Both flanges have holes extending from the mating surfaces that are aligned with a hole of the adjacent flange. One of several conventional threaded fastener configurations may be used to secure the flanges to each other. A bolt may extend through aligned holes of both flanges from a surface of one flange opposite the mating surface to position a bolt head abutting that opposite surface. The bolt may extend through the other flange to engage a nut that is threaded onto the bolt to abut a surface of the other flange opposite the mating surface. Alternatively, the hole of the second flange may be threaded to engage the bolt eliminating the need for a nut to engage the bolt. A threaded stud may be used in place of a bolt either to engage threads of one flange or to extend through both flanges and have nuts threaded onto the portions of the threaded stud that extend beyond the flange. 
     Bolted joints can provide a wide range of joint strengths depending on the size and separation of the bolts. A disadvantage of bolted joints is that they require several manufacturing operations, which can include machining the mating surfaces, drilling holes, and threading holes. Bolted joints also require bolts or threaded studs and nuts, and require assembly and tightening of the bolts to secure the components to each other. These operations are time consuming making bolted joints relatively expensive. 
     A less expensive joint that has been used to join components of fluid and gas distribution systems is a crimp joint. Crimp joints in the prior art have conventionally been formed by a uniform thickness flange extending generally perpendicularly from the outer surface of a first component and a lip of a second component that is deformed to overlie the flange and secure it against a mating surface of the second component. These prior art crimp joints are less expensive to manufacture and assemble than bolted joints. There are several disadvantages of prior art crimp joints that have limited their use. 
     One significant problem associated with such prior art crimp joints relates to the deformation of the lip that is required to capture the flange. Where the flange is perpendicular to the surrounding lip, the surrounding lip must be deformed so that a portion of the lip is perpendicular to its original configuration. This requires a large deformation of the surrounding lip and therefor requires that the lip be made of a material that will sustain such large deformation without cracking, becoming brittle, or otherwise failing or becoming susceptible to later failure. Materials that can be so deformed, such as steel, are relatively expensive and therefor increase the cost of the device. 
     Less expensive material has been used to form components of a fluid or gas system device that have a crimp joint where, rather than having a flange that is perpendicular to a surrounding lip, a flange is formed to have an upper surface opposite the flange mating surface that extends from an outer edge of the flange and away from the flange mating surface so that the flange upper surface forms an angle with the lip that is less than a perpendicular angle. The surrounding lip of the second component then is deformed over the edge of the flange to abut upper surface by an angle that is less than ninety degrees to form the crimp joint. Because less deformation of the lip is required to form the joint than perpendicular flanges, the material from which the surrounding lip is made need not be capable of sustaining high strain and therefor can be a less expensive material compared to material required for larger deformation. A recognized disadvantage of such joints is that they are less strong than a joint formed by deforming the surrounding lip to an angle of ninety degrees. 
     A need remains for a crimp joint that can be formed by components made of materials that cannot sustain high strain and that provides increased strength compared to prior crimp formed from components made of such materials. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes problems and disadvantages of prior crimp joints used to join components of fluid or gas distribution system devices. The joint according to the present invention comprises a flange that extends from a first component to a flange edge and a second component that defines a cavity to accept the flange. The cavity is defined by a second mating surface and a surrounding lip that extends from the second mating surface and is configured to closely surround the flange edge. The flange includes a flange mating surface that conforms to the second mating surface, and an engaging surface adjacent to the flange edge that preferably extends at least partially along the surrounding wall to form an angle with the surrounding wall that is less than ninety degrees when the flange mating surface is adjacent to the second mating surface. The engaging surface includes a bead that is formed to extend outwardly from the engaging surface at a location that is sufficiently near the flange edge that the surrounding lip will overlie the bead when the lip is deformed to overlie the engaging surface. 
     The crimped joint is formed by placing the flange of the first component in the cavity of the second component with the flange mating surface adjacent to the second mating surface of the second component. The surrounding lip is closely adjacent to the flange edge and is deformed toward the engaging surface of the flange until it overlies the engaging surface and conforms to the surface including the bead. 
     Accordingly, an object of the present invention is to provide a crimp joint that is less costly than prior crimp joints that support significant loads. 
     Another object of the present invention is to provide a crimp joint that does not require components of the joint to be manufactured from materials that can sustain high strains. 
     Yet another object of the present invention is to provide a crimp joint that provides greater strength than prior crimp joints formed by component made of materials that will not sustain high strains. 
     These and other objects and advantages of the present invention will be understood from the following description and drawings of an embodiment of a crimp joint according to the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a gas regulator having the bonnet and body joined by a crimp joint according to the present invention. 
     FIG. 2 is a partially cut away side elevation view of the bonnet of the gas regulator of FIG.  1 . 
     FIG. 3 is a front elevation view of the bonnet of the gas regulator of FIG.  1 . 
     FIG. 4 is a top view of the body of the gas regulator of FIG.  1 . 
     FIG. 5 is a side elevation view of the body of the gas regulator of FIG.  1 . 
     FIG. 6 is a sectional view of regions of the bonnet and body of the gas regulator depicted by FIG. 1 that form the crimp joint according to the present invention prior to deforming of the body to form the crimp joint. 
     FIG. 7 is a sectional view of crimp joint regions of the bonnet and body of the gas regulator depicted by FIG. 1 after the body is deformed to form a crimp joint between the bonnet and body according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a sectional view of an LP (liquefied petroleum) gas regulator  10  having a bonnet  12  and a body  14  joined by a crimp joint  20  according to the present invention. The bonnet  12  and the body  14  are die cast from a low ductility zinc alloy. 
     As best shown by FIGS. 2 and 3, the bonnet  12  includes a flange  22  that extends outwardly from the bonnet  12  around its periphery except at the location that vent housing  26  extends to the periphery of the bonnet  12 . The vent housing  26  includes a boss  28  that extends toward a flange material surface  42  and in an outward direction from the bonnet  12  toward a flange edge  44  from the vent housing  26 . As shown by FIGS. 1,  4 , and  5 , the body  14  includes a lip  32  that extends from the body  14 . The lip  32  is illustrated in FIGS. 4 and 5 and in phantom in FIG. 1 in its configuration prior to deformation to form the crimp joint  20 . As shown by FIG. 1, this original configuration of lip  32  partially defines a cavity  34  within which the flange  22  of the bonnet  12  to can be positioned. The lip  32  closely surrounds at least a portion of the flange  22  to position the bonnet  12  with respect to the body  14 . As shown by FIG. 4, the lip  32  does not extend continuously around the periphery of the body  14 , but rather defines an opening  33  that is sized to accept the boss  28  of the vent housing  26 . The lip  32  thereby both locates the bonnet  12  within the cavity  34  and at a desired orientation with respect to the body  14 . 
     FIGS. 2 and 6 show a cross-sectional view of the flange  22  and a section of the body  14  adjacent to the flange  22 . The flange  22  defines the flange mating surface  42  that faces outwardly in a first direction from the bonnet  12 . The flange edge  44  is adjacent to the outer extent of the flange mating surface  42 . An engaging surface  46  extends from the edge  44  inwardly toward the bonnet  12  overlying the flange mating surface  42 . The flange  22  of the described embodiment is circular having an outside diameter at the flange edge  44  of 3.25 inches. 
     As best shown by FIGS. 1 and 4, the body  14  defines a cavity  34  into which the flange  22  of the bonnet  12  is positioned to locate the bonnet  12  with respect to the body  14 . As shown by FIGS. 4 and 6, the cavity  34  defined by the body  14  is bounded in part by the second mating surface  52 . The second mating surface  52  faces outwardly from the body  14  and defines a continuous path around the body  14  adjacent to an interior  36  of the body  14  in which various components of the gas regulator  10  are contained. The second mating surface  52  is configured to conform to at least a portion of the flange mating surface  42 , as shown by FIGS. 1,  6 , and  7 . As best shown by FIGS. 1 and 6, the lip  32  extends outwardly from a location adjacent to the second mating surface  52  in a direction that is at least in part perpendicular to the second mating surface  52 . As best shown by FIG. 6, the lip  32  is defined between an inwardly facing inner surface  64  that extends from the second mating surface  52  to an edge  66  and an outwardly facing outer surface  68  that extends toward the body  14  from the edge  66 . The inner surface  64  and the second mating surface  52  define boundaries of the cavity  34  within which the flange  22  of the bonnet  12  is positioned, as shown by FIG.  1 . As also shown by FIG. 1, the lip  32  is sized to extend from the second mating surface  52  in is original configuration a distance that is sufficient to extend beyond the flange  22  when the flange mating surface  42  of the flange  22  is adjacent to the second mating surface  52 . 
     As best shown by FIGS. 4 and 6, the body  14  defines a recess  72  adjacent to the second mating surface  52  and opposite the lip  32 . The recess  72  extends continuously along the second mating surface  52  and into the body  14  from the second mating surface  52 . As shown by FIG. 6, the recess  72  is adjacent to a portion of the mating surface  42  of the flange  22  when the flange mating surface  42  overlies the second mating surface  52 . 
     The recess  72  is defined by an outer recess wall  74  that extends into the body  14  from an inner edge  54  of the second mating surface  52 . A lower surface  76  extends from the farthest extent of the wall  74  away from the second mating surface  52  to form a gap between the flange mating surface  42  and the lower surface  76 . The lower surface  76  extends from the outer recess wall  74  to meet an inner recess wall  78 . The inner recess wall  78  extends toward the flange mating surface  42  of the flange  22  to meet an upper surface  80 . The upper surface  80  that extends away from the second mating surface  52  to form a gap between the upper surface  80  and the flange mating surface  42  that is smaller than the gap between the lower surface  76  and the flange mating surface  42 . 
     A reinforced elastomer diaphragm  16  that is part of the regulator mechanism is positioned between the flange  22  and the body  14  and is held in place between the flange  22  and the body  14 . As shown by FIG. 1, the diaphragm  16  has a rib  18  at its periphery that is thicker than the inner portion of the diaphragm  16 . The rib  18  is captured within the recess  72  by the flange mating surface  42  of the flange  22 . An inner portion of the diaphragm  16  that is thinner than the rib  18  is captured between the flange mating surface  42  and the upper surface  80 . The rib is prevented from moving inwardly away from the second mating surface  52  by the inner recess wall  78 . As is evident from FIG. 1, the rib  18  conforms to the flange mating surface  42  and the lower surface  76  to provide a seal that prevents fluid or gas within the regulator  10  from leaking between the flange  22  and the body  14 . 
     As best shown by FIGS. 6 and 7, the engaging surface  46  is oriented and configured to engage the lip  32  to provide a strengthened crimp joint and to limit the deformation of the lip  32  to form the joint. The engaging surface  46  includes a bead  82  adjacent to the edge  44  and a surface  84  that meets the bead  82  opposite the edge  44  and extends from the bead  82  away from the edge  44 . 
     The surface  84  is oriented to extend away from the edge  44  and along the inner surface  64  of the lip  32  and away from the second mating surface  52 . As best shown by FIG. 6, because the surface  84  extends away from the second mating surface  52 , the deformation required to bring the lip  32  into engaging contact with the engaging surface  46  of the flange  22  is measured by an angle A between the surface  84  and the inner surface  64 . As presently preferred, the angle A is approximately seventy degrees. 
     The bead  82  extends from the flange  22  in a direction away from the surface  84  and inwardly away from the flange edge  44 . The bead  82  is sized to deform and to engage and deform the lip  32  when that lip  32  is deformed to overlie the flange engaging surface  46  to form the crimp joint  20 . As best shown by FIG. 7, the lip  32  is deformed from its original configuration extending beyond the flange  22  to overlie and conform to the engaging surface  46  to form the crimp joint  20 . The lip  32  may be deformed by any conventional means, including bending, roll forming, and orbital riveting. Deforming by roller wheels is presently preferred for forming the crimp joint  20  of the described embodiment. 
     The bead  82  is sized based on the ductility of the material from which the lip  32  is formed and the thickness of the lip  32  from the inner surface  64  to the outer surface  68 . The height of the lip  32  of the described embodiments from the second mating surface  52  to the edge  66  is 0.205 inches. The thickness of the lip  32  of the described embodiments from the outer surface  68  to the inner surface  64  is approximately 0.078 inches adjacent to the second mating surface  52  and is approximately 0.037 inches at the edge  66 . The thickness of the flange  22  at the flange edge  44 , from the second mating surface  52  to the farthest extend of the bead  82 , is approximately 0.137 inches. 
     When the regulator  10  having the crimp joint  20  is subjected to a pressure within the body and bonnet, that pressure tends to force the bonnet  12  away from the body  14  and to therefor open the crimp joint  20 . That internal pressure causes the flange  22  to push against the lip  32  to urge the lip  32  to approach its original configuration shown by FIG. 6 from the deformed configuration shown by FIG.  7 . The bead  82  is sized and located to engage, or grip the lip  32  near the flange edge  44 , as shown by FIG. 7, to resist movement of the flange  22  away from the second mating surface  52 . 
     The dimensions of the bead  82  of the engaging surface  46  determine its effectiveness in increasing the strength of the crimp joint  20 . The bead  82  is sized to have a width W that is sufficiently large to prevent a shearing of the bead  82  from the flange  22  when the joint  20  is subjected to load due to pressure within the bonnet  12  and the body  14 . The width W of the bead  82  must be sufficiently narrow to cause the lip  32  to form around the bead  82  as the lip  32  is deformed to overlie the engaging surface  46 . As presently preferred for the described embodiment, W is within the range of 0.022-0.030 inches. The height H of the bead  82  must be sufficient to assure that the bead will not be deformed to an ineffective height when the wall  32  is deformed to overlie the engaging surface  46 . The height H of the bead  82  must also not be so large that it will weaken the wall  32  by causing an unacceptably large deformation of the lip  32  when the lip  32  is deformed to overlie the engaging surface  46  and to engage the bead  82 . As presently preferred for the described embodiment, H is within the range of 0.007-0.012 inches. 
     The effectiveness of the bead  82  to increase the strength of the crimp joint  20  of the described embodiment has been evaluated by measuring the amount of pressure within the bonnet  12  and the body  14  that is required to cause the lip  32  to deform to allow the flange  22  to separate from the second mating surface  52 . That pressure was measured for the flange  22  having the described bead  82 , and for a smooth flange having not bead, that is the surface  84  extends uninterrupted to the flange edge  44 . The pressure required to separate the flange  22  having the bead  82  from the second mating surface  52  was found to be at least 150 percent of the pressure required to separate a flange not having the bead  82  from the second mating surface  52 . 
     The present invention has been described by reference to preferred embodiments of the invention. Those skilled in the art will recognize that changes may be made without departing from the scope of the invention.