Abstract:
A process of roll forming a tubular metallic body for a fluid connector comprised of first affixing a tubular metallic body of substantially constant diameter in a roll forming machine, then positioning a series of freely rotatable independent tools in a circumferential pattern surrounding the tubular body. The tools are then rotated within a predetermined velocity range and minimal radial contact is applied between the series of tools and the tubular body. This contact forms at least one radial groove in the tubular body, smoothes the outer surface of the tubular body and decreases the outside diameter of a portion of the tubular body for a predetermined distance along its periphery at a constant, uniform rate. Also the proximate end of the decreasing diameter portion is rounded. Further, the metallic tubular body is fabricated from a 5000 series aluminum alloy.

Description:
CROSS-REFERENCE TO RELATED CASES  
       [0001]    The present application claims the benefit of the filing date of U.S. Provisional Application Serial No. 60/438,846 filed Jan. 8, 2003, the disclosure of which is incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention is directed generally to the process of forming a tube element of a tubular connector, and more particularly to forming a 5000 series aluminum alloy tube element.  
         BACKGROUND OF THE INVENTION  
         [0003]    Tubular connectors are attached to fluid conveying conduits and form an assembly that can be used in fluid systems. Tubular connectors are generally comprised of a tube and a shell usually made of a metallic material. The shell, which is fitted over the conduit, is affixed to the tube, which is inserted into the conduit. The shell is then inwardly or radially compressed so that the conduit is retained and sealed there-between. A proper seal and full physical retention are necessary so that leakage and separation are avoided.  
           [0004]    Most currently available tubular connectors utilize tube designs with retaining barbs on the tube outer surface so that a seal is established between the barbs and the inner surface of the conduit. Examples of these types of tube designs are shown in prior art constructions such as U.S. Pat. No. 5,387,016 to Joseph et al., U.S. Pat. No. 5,961,157 to Baron et al., and French Pat. 2,675,880-A1 to Pineda. These barbs also provide a retention means between the tube and the conduit inner surface when the shell component is inwardly compressed. A disadvantage with this type of design is that the barbs can damage the inner surface of the conduit, thus providing a leak path for the fluid. Due to the snug fit between the tube and the conduit, the conduit inner surface can also be damaged when the tube is inserted inside the conduit.  
           [0005]    Other currently available tubular connectors utilize O-rings, or other forms of elastomeric seals, retained on their outer surfaces in order to provide a seal between the tube and the conduit. Examples of these types of designs are shown in prior art constructions such as U.S. Pat. No. 5,044,671 to Chisnell et al., U.S. Pat. No. 5,378,023 to Olbrich, U.S. Pat. No. 5,984,376 to Lampe, and the aforementioned French Pat. 2,675,880-A1 to Pineda. In each of these designs, the O-rings are used to provide a seal between the two metal components. Other design attributes, such as barbs or ridges provide the retaining means in this type of design. As mentioned above, the barbs can possibly damage the inner surface of the conduit, providing a leak path. Another disadvantage of these designs is that during assembly of the conduit with the connector, the O-ring can move with the conduit, thus leaving its designed receiving area and seriously impairing its sealing function.  
           [0006]    Roll forming techniques for the construction of tubular connectors is advantageous since the formed areas are not left with chips, flakes or sharp edges. Other currently available tubular connectors have roll formed tubular connectors, but only with select metal material. 5000 series aluminum alloys are desired metallic materials since they are lighter and stronger than most currently used aluminum alloy materials. Roll forming these materials though is difficult due to their poor forming properties. It is common to shear portions of the part being formed during the fabrication thereof.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides a process for roll-forming a tube element of a tubular connector made from 5000 series aluminum. The process rotates, at a designed speed, a plurality of forming tools, or rollers, in order to apply minimal contact to the tube without causing any structural damage to the tube.  
           [0008]    More specifically, the present invention provides a process of roll forming a tubular metallic body for a fluid connector. The process is comprised of first affixing a tubular metallic body of substantially constant diameter in a roll forming machine, then positioning a series of freely rotatable independent tools in a circumferential pattern surrounding the tubular body. The tools are then rotated within a predetermined velocity range and minimal radial contact is applied between the series of tools and the tubular body. This contact forms at least one radial groove in the tubular body, smoothes the outer surface of the tubular body and decreases the outside diameter of a portion of the tubular body for a predetermined distance along its periphery at a constant, uniform rate. Also the proximate end of the decreasing diameter portion is rounded. Another feature of the noted process has the metallic tubular body being fabricated from a 5000 series aluminum alloy.  
           [0009]    Another feature of the noted process includes, during the forming step, moving material to the proximate end and forming a rounded, rolled-over nipple nose. A further feature of the noted process includes the step of smoothing the tubular body excluding the grooves, the decreasing diameter portion and the rounded proximate end.  
           [0010]    Still yet another feature includes the noted process wherein the series of tools contains three essentially equally spaced parallel rollers each having at least one protrusion extending from its outer peripheral surface, and the minimal contact occurs substantially simultaneously between each of the at least one protrusion and the tubular body. Another feature includes the noted process where the rotational velocity of the series of tools is in the range of 300-800 rpm.  
           [0011]    Another attribute of the noted process has the decreasing diameter portion extending from one of the at least one annular grooves towards the proximate end. A further attribute has the decreasing diameter portion with an about 2° pitch. Still yet another feature has the at least one annular groove including two axially spaced, parallel, substantially similar grooves. Further features and advantages of the present invention will become apparent to those skilled in the art upon review of the following specification in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a longitudinal cross-sectional view of a hose assembly embodying the present invention.  
         [0013]    [0013]FIG. 2 is a longitudinal cross-sectional view of a tubular element of the present invention.  
         [0014]    [0014]FIG. 3 is a longitudinal cross-sectional view of the tubular element, similar to FIG. 2, with the addition of O-rings in place.  
         [0015]    [0015]FIG. 4 is a longitudinal cross-sectional view of a tubular connector, comprised of the tubular element, as shown in FIG. 2, with the addition of an affixed shell.  
         [0016]    [0016]FIG. 5 a  is a longitudinal cross-sectional view of a first roller tool used in the present invention forming process.  
         [0017]    [0017]FIG. 5 b  is a longitudinal cross-sectional view of a second roller tool used in the present invention forming process.  
         [0018]    [0018]FIG. 5 c  is a longitudinal cross-sectional view of a third roller tool used in the present invention forming process.  
         [0019]    [0019]FIG. 6 is an enlarged partial view of the second roller tool surface area designated by circle  6 - 6  in FIG. 5 a.    
         [0020]    [0020]FIG. 7 is an isometric view showing the three roller tools, together with the tubular element, used in the present invention forming methods. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    Referring to the drawings, and initially to FIG. 1, a hose assembly  20 , including a tubular connector  30  and a conduit  25 , is shown. Tubular connector  30 , comprised of a shell  38  and a tube  40 , is designed for fixed attachment to a conduit  25  used for fluid transfer in various applications, for example automotive. As is discussed in detail below, the present invention provides a simplified manufacturing process for developing contours in a smooth-finish tube so as to produce contoured tube  40 , as best seen in FIG. 2, having ideal retention and sealing attributes with reference to conduit  25 . In addition, this new design and its manufacturing process ensure that the inner peripheral surface of conduit  25  is not damaged during fabrication of hose assembly  20 .  
         [0022]    Tube  40  has several unique features that assist in the sealing engagement of conduit  25  with connector  30 . A leading outer annular edge, or nipple nose  44 , of tube  40 , is rolled-over or relieved in order to aid with the installation of conduit  25  onto tube  40 . The outer diameter of tube  40  is dimensionally close to the inner diameter of conduit  25  so that a proper seal can be achieved. Therefore, when conduit  25  is fitted onto tube  40 , nipple nose  44  can impair the integrity of the inner peripheral surface of conduit  25  if nipple nose  44  is not rounded. For example, if nipple nose  44  has a sharp outer edge, the inner peripheral surface of conduit  25  can be nicked or scratched, thus providing a possible leakage path for the fluid being transferred through hose assembly  20 .  
         [0023]    Tube  40  has a smooth, slightly tapered outer surface portion  49  or a uniformly decreasing outside diameter portion  49 , extending from nipple nose  44  to a first rounded peripheral groove  54 , formed within tube  40 . For example, tapered surface  49  can have a 2° pitch or taper. As mentioned above, the dimensional interface between the inner peripheral surface of conduit  25  and the outer peripheral surface of tube  40  is close or snug so that a full circumferential seal can be formed. The sloped or tapered surface  49  assists in the connection of hose assembly  20  with tube  40  when conduit  25  is united with tube  40 , as well as ensures that the inner peripheral surface of conduit  25  remains undamaged. First rounded groove  54  extends peripherally around the circumference of tube  40  and serves to receive an O-ring  56 , as best seen in FIG. 3, having a greater outer diameter than that of tapered surface  49 . During the connection of conduit  25  with tube  40 , when conduit  25  and tube  40  slide relative to each other, it is imperative that O-ring  56  stays within first groove  54  and does not move with conduit  25 . Tapered surface  49  ensures that O-ring  56  not only remains located within first groove  54 , but also functions as a peripheral seal between tube  40  and conduit  25 .  
         [0024]    A smooth, flat outer surface portion  59  of tube  40  extends between first groove  54  and a second rounded groove  64  formed within tube  40 . Similar to first groove  54 , second groove  64  extends peripherally around the circumference of tube  40  and also serves to receive an O-ring  66  that provides a further peripheral seal between conduit  25  and tube  40 . O-rings  56 ,  66  have an inner diameter less than, for example in the range of 10-30%, the inner diameter of grooves  54 ,  64  such that O-rings  56 ,  66  are stretched in order to fit within grooves  54 ,  64 , thus providing better retentions thereof.  
         [0025]    Both surface portions  49  and  59  have a smooth surface or profile, contrary to other tubular designs that have a barbed outer profile. Typically, tubes use a barbed profile in order to provide retention between the conduit and tube. The barbs grip the inner peripheral surface of the conduit, which, for example, is made of an elastomeric or thermoplastic material, thus giving the conduit a greater resistance to being pulled out of the connector. The barbs also serve to provide a sealant surface between the conduit and the tube. Typically, if a barbed tube is used in conjunction with a thermoplastic or elastomeric conduit, a chemical sealant, such as Chemlock™, is applied to the barbs in order to produce a chemical seal between the tube and the conduit. Tubes having a barbed outer profile and using a sealant do not require O-rings on their peripheral surfaces since the sealant already provides the seal. Due to safety issues and new environmental standards, the use of a chemical sealant is not preferred. The use of O-rings  56 ,  66  not only adds sealing and retention properties to hose assembly  20 , but also provides a safer, and more environmentally friendly, fabrication or assembly process for the end user. In addition, while barbs provide sealing and retaining means, they can also damage the hose inner peripheral surface and provide a possible leak path for the fluid being transferred. Although the smooth profiles of surface portions  49  and  59  do not provide retention means, they will not damage the inner peripheral surface of conduit  25 . The noted smooth profiles also simplify the manufacturing process of tube  40  since barbs need not be machined into its outer surface.  
         [0026]    Located on the side opposite of flat surface portion  59 , of tube  40 , and extending from second groove  64 , is another smooth, flat surface portion  69 . Surface portion  69  extends from second groove  64  to a generally rectangular peripheral retaining groove, or notch  74 . Surface portion  69  extends well past second O-ring groove  64  (towards groove  74 ) such that the proximate end of conduit  25 , when fully inserted into connector  30  (as shown in FIG. 1) also extends well past second O-ring groove  64 . This insures that a full peripheral proper seal between O-ring  66 , groove  64  and conduit  25  will exist even if the proximate end of conduit  25  is not properly cut prior to its insertion into tubular connector  20 . Specifically, it is common for the proximate end of conduit  25  to be improperly cut at an angle, rather than squarely. If conduit  25  is cut at an angle, the shorter, relieved portion will still not be in close axial proximity to second groove  64 . In other words, due to the axial or longitudinal distance between notch  74  and groove  64 , an improperly angle cut conduit  25  will still be completely sealed by O-ring  66 . Generally rectangular retaining groove or notch  74  extends peripherally around the circumference of tube  40  and, as shown in FIG. 4, serves to affixedly receive a coupling shell, or socket,  38 . Shell  38  has an inner, annular, vertically oriented surface portion  84  which acts as an abutting face for conduit  25  when fully inserted into connector  30 .  
         [0027]    Referring to FIGS. 2 and 3, grooves  54 ,  64 , which are substantially similar have a total radial depth such that the outer peripheral surface of O-rings  56 ,  66  extend above surfaces  49 ,  59 , and  69 , by approximately 0.010-0.020″. The formed radii at the sides and bottom of grooves  54 ,  64  combine to comprise the total depth. For example, groove  64  has a side radii  71  of 0.025″ and a bottom radius  72  of 0.015″ for a total depth of 0.040″. By utilizing these differing contours, radii  71  and  72  have opposed annular transition lines therebetween that function to retain O-ring  66 , when tube  40  is united with tubular connector  30  and passes over O-ring  66 . Groove  54  and O-ring  56  have a substantially similar contour and retention means. The lateral width of grooves  54 ,  64  is such that when O-rings  56 ,  66  are compressed, as seen in FIG. 1, they completely fill grooves  54 ,  64  and continue to have curvelinear annular portions therein extending above surfaces  49 ,  59 , and  69 .  
         [0028]    To properly fabricate hose assembly  20 , the following steps are taken. Referring to FIGS. 1 &amp; 4, conduit  25  is inserted into tubular connector  30  such that tube  40  is positioned inside of conduit  25  and shell  38  covers the outer surface of conduit  25 . As previously detailed, conduit  25  is initially placed over nipple nose  44  which provides a smooth lead for the inner peripheral surface of conduit  25 . Conduit  25  then travels over tapered surface  49  so that its inner diameter expands while progressing over O-ring  56 . Due to the contour of groove  54  and tapered surface  49 , O-ring  56  remains within groove  54  during the movement of conduit  25 . Conduit  25  moves along flat surface  59  and is still expanded due to the angle of tapered surface  49 . Conduit  25  then passes over, without dislodging, O-ring  66 , and moves along surface  69  until it abuts inner annular surface  84  of shell  38 .  
         [0029]    Once conduit  25  has been fully inserted into connector  30 , shell  38  is intermittently directed radially inwardly, via permanent deformation, so that successive axial portions of conduit  25  are radially compressed between shell  38  and tube  40 . Shell  38  can be deformed inwardly by varying methods, well known in the art, such as a crimping operation or by the tightening of circumferential bands (not shown) around the outer surface of shell  38 . Regardless of which method is utilized, the inwardly directed forces on shell  38  preferably should not be applied directly over O-rings  56  and  66 . In order to provide the best possible sealing and retention between conduit  25  and connector  30 , the inwardly directed forces are applied in three areas: axially between nipple nose  44  and first groove  54  (as indicated by a first detent  90 ), axially between first groove  54  and second groove  64  (as indicated by a second detent  91 ), and axially between second groove  64  and retaining groove  74  (as indicated by a third detent  92 ). When fabricated in the above fashion, O-rings  56  and  66  are compressed and completely fill grooves  54  and  64 . The rounded outer extents of O-rings  56  and  66  remain at a greater outer diameter than that of tube  40  and provide both the retaining means, relative to conduit  25 , as well as acting in peripheral sealing capacity relative to conduit  25 . Since tube  40  is provided with a smooth outer surface or profile and thus does not have a barbed profile, O-rings  56  and  66  replace both the sealing and retention functions of the barbs.  
         [0030]    The process of forming tube  40  will now be discussed in more detail. Referring to FIGS. 5 a ,  5   b , and  5   c , the tools used for the forming process are shown in the form of cylindrical rollers,  77 ,  78  and  79 . First roller  77 , shown in FIG. 5 a , has a protrusion  80  extending from its outer periphery that is shaped similar to second groove  64  of tube  40 . Protrusion  80  is positioned closer to the front or nose portion  85  of roller  77  than to its base  86 . Second roller  78 , shown in FIG. 5 b , has a protrusion  81  extending from its outer periphery that is shaped similar to first groove  54  of tube  40 . Protrusion  81  is positioned closer to the base  89  of roller  78  than to its nose  88 . Third roller  79 , shown in FIG. 5 c , has two first and second protrusions  82  and  83  respectively, both extending from its outer periphery. First protrusion  82  is shaped similar to second groove  64  while second protrusion  83  is shaped similar to first groove  54 . When all of the rollers are situated for the forming process, as shown in FIG. 7, third roller first protrusion  82  is radially aligned with first roller protrusion  80 , and third roller second protrusion  83  is radially aligned with second roller protrusion  81 .  
         [0031]    Referring to FIG. 6, an enlarged outer circumferential surface segment  94 , close to base  89  of second roller  78 , is shown and includes a tapered portion  98  and a radiused portion  99  extending between protrusion  81  and base  89 . Surface segment  94  is also indicative of the surface of rollers  77  and  79 . Tapered portion  98  extends from protrusion  81  into a radiused portion  99 . Tapered portion  98  is angled similarly to tapered surface  49  of tube  40 , for example at a 2° pitch. Likewise, radiused portion  99  has a profile similar to that of tube nipple nose  44 . Roller nose portions  85 ,  88  and  95  each are tapered at an approximate angle range of 25°-45°. This angle provides a relief for and prevents tube material from flowing into tube retaining groove  74  during the tube forming process.  
         [0032]    In order to form tube  40 , rollers  77 ,  78  &amp;  79  are positioned on approximately triangularly-spaced, parallel axis roller holders (not shown) with cylindrical bearing liners and pins holding them in place. The roller holders in-turn hold the rollers in a roll-forming machine (not shown). Each roller is journaled by two-spaced needle bearings (not shown) located on its inner peripheral surface in order to allow each roller to spin or rotate independently of the others. Rollers  77 - 79  (and their respective roller holders) are affixed to a cylindrical shaft on the roll-forming machine and positioned in a fixed angular position (as shown in FIG. 7), approximately 120° apart from one another. The cylindrical shaft rotates, for example, at a speed of 300-800 rpm for forming a 5000 series aluminum alloy tube. A constant diameter 5000 series aluminum tube is placed into a slot opening in the front of the machine while grip blocks, or jaws (not shown), close to hold the tube firmly in place. Rollers  77 - 79  extend radially inwardly and contact the tube simultaneously. Rollers  77  and  78 , which have but one protrusion each, contact the tube and roughly form or preform grooves  64  and  54  respectively. Since these rollers have only one protrusion, the forces produced by the radial contact are concentrated on the one protrusion, allowing more material to be displaced with less contact necessary. Roller  79 , having the two protrusions  82  and  83 , final-form the grooves  54 ,  64  and particularly the radii at the sides and bottom of both grooves  54  and  64 .  
         [0033]    When contact is made with the constant diameter tube, rollers  77 - 79  spin freely and displace, or move, the metallic material, thus forming grooves  54  and  64 . Without the ability to spin freely, rollers  77 - 79  would act like a cutting tool, thereby removing material. When moving the material, metal flows from underneath protrusions  80 - 83  in both axial directions. In a similar manner, tapered surface  98  of each roller  77 - 79  also displaces material toward radiused portion  99 . The displacement of material by tapered surface  98  on rollers  77 - 79  forms tapered surface  49  on tube  40 . Radiused portion  99 , on each roller  77 - 79 , contacts the annular outer end on the tube and provides the rolled-over shape to produce finished nipple nose  44 . The material displaced from grooves  54 ,  64  and by tapered surface  98  also helps to finish the radius on nipple nose  44  so that it is rounded and does not damage the inside of conduit  25  during fabrication of assembly  20 . After the proper formation of grooves  54 ,  64 , taper  49  and nipple nose  44 , rollers  77 - 79  return to their original position and grip blocks release tube  40 .  
         [0034]    Typical uses for 5000 series aluminum alloys are primarily for sheet metal applications such as road signs and exterior bodies of small marine craft. Due to its excellent corrosion resistance and overall toughness, its use in mobile fluid transfer applications is desired. Unfortunately the 5000 series alloys suffer from poor machinability, so roll-forming techniques must be used. In order to roll-form 5000 series aluminum alloy materials, the contact pressure of rollers  77 - 79  for forming tube  40  needs to be reduced from that of conventional roll-forming processes known in the art. Likewise, the rotational speed of the cylindrical shaft holding rollers  77 - 79  also has to be reduced. Known roll-forming processes have rotational speeds of up to 1400 rpm, when forming metals such as 3000 series aluminum alloy material. This latter speed will separate the portions of tube nipple from tube  40  if performed on a 5000 series aluminum alloy material. In order to reduce the contact and pressure, rollers  77 ,  78  are designed with only one protrusion  80  and  81 , respectively. By reducing the surface contact between rollers  77 ,  78  and tube  40 , a smooth finish is produced in grooves  54  and  64 , without leaving chips or flakes. Since grooves  54  and  64  are a primary sealing surfaces, they need to be clean and smooth. Similar to excessive rotational speed, too much contact (or torque) between rollers  77 - 79  and tube  40  will cause a portion of tube  40  to be separated. With but one protrusion on rollers  77  and  78 , the torque applied to tube  40  is reduced by about one third. Minimal contact coupled with the slower rotational speed, as discussed above, provides a workable process combination that keeps tube  40  intact during its roll-forming process.  
         [0035]    It should be noted that the present invention is not limited to the specified preferred embodiments and principles. Those skilled in the art to which this invention pertains may formulate modifications and alterations to the present invention. These changes, which rely upon the teachings by which this disclosure has advanced, are properly considered within the scope of this invention as defined by the appended claims.