Abstract:
A method and apparatus for forming a tube and connector assembly. The tube is formed in a co-extrusion process to provide a multi-ply tube and the multi-ply tube is thereafter delivered to an injection die assembly where a connector is molded onto the end of the tube. The molded on connector provides a ready and efficient means of providing a connector for the tube and further encapsulates the tube end so as to preclude separation of the plies of the tube even in a heavy duty usage environment. The connector may comprise a coaxial connector in which the central axis of the connector is coaxial with the central axis of the tube end portion over which it is molded or may comprise a right angle connector in which the central axis of the connector is at a right angle to the central axis of the tube end portion over which it is molded.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to tubes and connectors and more particularly to a method and apparatus for forming a tube and connector assembly.  
           [0002]    Tubing is extensively used in automotive applications. In a typical automotive application, the tube exterior is subjected to different damaging elements than the tube interior. For example, the tube exterior is typically exposed to sodium chloride (winter road salt), calcium chloride (summer wet road treatment), and zinc chloride (from adjacent ferrous automotive elements that have been dipped in zinc). By contrast, the tube interior is subjected to the chemistry of the substance being transmitted through the tube, for example the chemistry of polyglycol brake fluid.  
           [0003]    In an effort to address this exterior/interior chemical damage disparity, compromise materials have been proposed in an effort to partially satisfy the peculiar concerns of exterior and interior. However, this comprise solution does not totally satisfy either need. In a further effort to address this chemical damage disparity, co-extruded tubes have been proposed so that each ply of the tube may be customized to address the peculiar needs of that ply. However, the plies of co-extruded tubes have tended to separate in usage, particularly proximate the ends of the tubes.  
         SUMMARY OF THE INVENTION  
         [0004]    This invention is directed to the provision of an improved tube and connector assembly.  
           [0005]    According to a feature of the invention, a method is provided for forming a tube and connector assembly comprising forming a tube in a co-extruding operation and forming a connector on one end of the co-extruded tube in a molding operation. The molded on connector precludes separation of the plies of the co-extruded tube even in heavy duty applications and the formation of the connector on the end of the tube in a molding operation provides a quick and efficient means of providing the connector.  
           [0006]    In one embodiment of the invention, the connector includes a bore coaxial with the tube bore and in another embodiment the connector includes a bore disposed at a right angle to the tube bore.  
           [0007]    According to a further feature of the invention, an apparatus is provided for forming a tube and connector assembly comprising a co-extrusion die assembly operative to form a multi-ply tube and an injection die assembly operative to receive one end of the multi-ply tube and mold a connector onto the received end of the tube. This arrangement provides a ready and efficient means of forming a multi-ply tube with a molded on connector.  
           [0008]    According to a further feature of the invention, the injection die assembly defines a cavity, a first bore opening in the cavity and sized to receive the tube end, and a second bore opening in the cavity; and the injection die assembly further includes an axial core slidably received in the second bore and having a free inboard end projecting into the cavity and positionable adjacent the free inboard end of the tube end received in the first bore. This arrangement provides a ready and efficient means for molding the connector onto the tube end.  
           [0009]    Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:  
         [0011]    [0011]FIG. 1 is a schematic view showing the basic methodology of the invention whereby a multi-ply tube is formed and a connector is molded onto an end of the multi-ply tube;  
         [0012]    [0012]FIGS. 1A and 1B illustrate alternate connector and tube assemblies formable by the invention methodology;  
         [0013]    [0013]FIG. 2 illustrates an injection die assembly for use in forming a connector that is coaxial with the central tube axis;  
         [0014]    [0014]FIG. 3 illustrates an injection die assembly for use in forming a connector that is disposed at a right angle to the central tube axis;  
         [0015]    [0015]FIG. 4 is a cross-sectional view of a coaxial tube and connector assembly;  
         [0016]    [0016]FIG. 5 is a cross-sectional view of a right angle tube and connector assembly; and  
         [0017]    [0017]FIG. 6 is a cross-sectional view taken on line  6 - 6  of FIGS.  4 / 5 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    As seen in FIG. 1, a connector is formed on the end of a tube  10  in a co-extrusion and injection molding operation. The connector may either comprise a coaxial connector  12  formed coaxially with respect to the central tube axis, as seen in FIG. 1A, or may comprise a right angle connector  14  formed at a right angle with respect to the central tube axis, as seen in FIG. 1B. In the formation of the tube and coaxial connector assembly, a co-extrusion die assembly  16  is employed to form the multi-ply tube  10  and a coaxial injection die assembly  18  is employed to mold the coaxial connector  12  onto the end  10   a  of the tube. In the formation of the tube and right angle connector assembly, co-extrusion die assembly  16  is employed to form the multi-ply tube  10  and a right angle injection die assembly  20  is employed to mold the right angle connector  14  onto the end  10   a  of the tube.  
         [0019]    With additional reference to FIGS. 1A and 4, coaxial connector  12  includes a tubular portion  12   a  telescopically positioned over the tube end portion  10   a , and a fitting portion  12   b . It will be understood that fitting portion  12   b  is arranged to fit telescopically within a port defined in an apparatus to which it is desired to deliver fluid through the tube  10  and, in known manner, includes a groove  12   c  for receipt of an O-ring and a further groove  12   d  for receipt of a suitable clip whereby to fixedly secure the fitting portion  10   b  to the apparatus defining the port. A central, axially extending bore  12   e  is defined in fitting portion  12   b  and a counter bore  12   f  is defined in tubular portion  12   a.    
         [0020]    With reference to FIGS. 1B and 5, right angle connector  14  includes a tubular portion  14   a  telescopically positioned over tube end portion  10   a , a main body portion  14   b , and a fitting portion  14   c  extending at a right angle to tubular portion  10   a . It will be understood that fitting portion  14   c  is arranged to fit telescopically within a port defined in an apparatus to which it is desired to deliver fluid through the tube  10  and, in known manner, includes a groove  14   d  for receipt of an O-ring and a further groove  14   e  for receipt of a suitable clip whereby to fixedly secure the fitting portion  14   c  to the apparatus defining the port. A central axially extending bore  14   f  is defined in fitting portion  14   c  and in main body portion  14   b . Bore  14   f  includes a main body portion  14   g  and a reduced diameter, relatively flat portion  14   h  positioned in overlying relation to the open end of tube end portion  10   a . The central axis of bore  14   f  will be seen to be disposed at a right angle to the central axis of the tube  10  so that the connector  14  forms a right angle connector with respect to the tube  10 .  
         [0021]    The manner in which the tube  10  and coaxial connector  12  assembly is formed is seen in FIG. 1 with reference to co-extrusion die assembly  16  and coaxial injection die assembly  18 . Specifically, an inner tube ply or layer  10   b  is formed by a first extrusion die  22  of known form and employing a central core  22   a  in known manner, an outer tube ply or layer  10   c  is formed over inner ply  10   b  by a second extrusion die  24 . The molten material  26  that is forced under pressure through extrusion die  20  to form inner ply  10   b  may comprise, for example, a Nylon 66 material and the molten material  28  that is forced under pressure through extrusion die  24  in surrounding relation to inner ply  10   b  may comprise, for example, a Nylon 12 material. For a tube having an outside diameter of 8.00 mm., outer ply  10   c  may have a thickness of 0.50 mm. and inner ply  10   b  may have a thickness of 1.50 mm.  
         [0022]    Following the formation of the multi-ply tube  10  in the extrusion die assembly  16 , the tube is allowed to set and is then suitably transferred to injection die assembly  18  (see also FIG. 2).  
         [0023]    Injection die assembly  18  includes a lower die or mold half  30 , an upper die or mold half  32 , and an axial core  34 . Lower die  30  defines a lower half  30   a  of a mold cavity, a semicircular lower groove  30   b  sized to receive tube end  10   a , and a semicircular lower groove half  30   c  sized to receive axial core  34 . It will be understood that upper die  32  defines a complimentary upper half of the mold cavity and complimentary upper groove halves coacting with the mold cavity  30   a  and the semicircular grooves  30   b  and  30   c  to form the total mold cavity, a cylindrical bore  36  for slidable receipt of tube end portion  10   a , and a cylindrical bore  38  for slidable receipt of axial core  34 .  
         [0024]    Die assembly  18 , in known manner, further includes a sprue  40 , a runner  42  extending from the lower end of the sprue to the mold cavity, and a gate  44  at the entry of the runner into the mold cavity. Axial core  34  has a cylindrical configuration including a circular inboard end face  34   a.    
         [0025]    In the use of the die assembly  18  to form the connector  12  on the tube end portion  10   a ; tube end portion  10   a  is positioned in the groove  30   b  of the lower die to position the inboard end  10   d  of the tube end portion in the mold cavity; axial core  34  is positioned in groove  34   c  with inboard end face  34   a  abutting the annular inboard end face  10   e  of the inboard tube end; upper die  32  is positioned over the lower die;  
         [0026]    molten plastic material (such for example as Nylon 12 or Nylon 612 glass reinforced) is supplied to sprue  40  for passage through runner  42  and through gate  44  into the mold cavity to fill the mold cavity in surrounding relation to the inboard tube end  10   d  and the axial core; and, following setting of the plastic material, the upper die is removed from the lower die and the axial core  34  is removed. This molding procedure forms a connector  12  fixedly secured to the tube end portion  10   d  and having an axial bore  12   b  communicating with the open end of the tube. The tube end portion  10   d  will be seen to occupy the counter bore  12   f  of the connector.  
         [0027]    The manner in which the tube  10  and right angle connector  14  assembly is formed is seen in FIG. 1 with reference to co-extrusion die assembly  16  and right angle injection die assembly  20 . The multi-ply tube, including inner ply  10   b  and co-extruded outer ply  10   c , is formed in the same manner, of the same materials, and of the same ply thicknesses, as described with respect to the formation of the tube  10  and coaxial connector  12  assembly.  
         [0028]    Following the formation of the multi-ply tube  10  in the extrusion die assembly  16 , the tubing is allowed to set and is then suitably transferred to injection mold assembly  20  (see also FIG. 3). Injection mold assembly  20  includes a lower die or mold half  50 , an upper die or mold half  52 , and an axial core  54 . The lower die  50  defines a lower half  50   a  of a mold cavity, a semicircular lower groove half  50   b  sized to receive tube  10 , and a semicircular lower groove half  50   c  sized to receive axial core  54 . It will be understood that upper die  52  defines a complimentary upper half of the mold cavity and complimentary upper groove halves coacting with the mold cavity  50   a  and the semicircular grooves  50   b  and  50   c  to form the total mold cavity, a cylindrical bore  56  for slidable receipt of tube end portion  10   a , and a cylindrical bore  58  for slidable receipt of axial core  54 .  
         [0029]    The die assembly, in known manner, further includes a sprue  60 , a runner  62  extending from the lower end of the screw to the mold cavity, and a gate  64  at the entry of the runner  62  into the mold cavity.  
         [0030]    Axial core  54  includes a cylindrical main body portion  54   a  slidably received in bore  50   c  and a flat inboard end portion  54   b  defining a flat sealing surface  54   c  and connected to the main body portion  54   a  by chamferred surfaces  54   d  and  54   e.    
         [0031]    In the use of die assembly  20  to form the connector  14  on the tube end portion  10   a , a tube end portion  10   a  is positioned in the groove  50   b  of the lower die  50  to position the inboard end  10   d  of the tube in the mold cavity; axial core  54  is positioned in the groove  50   c  with end portion  54   b  overlying the open end of the tube and sealing surface  54   c  sealingly engaging the annular end face  10   e  of the tube; the upper die  52  is positioned over the lower die; molten plastic material (such for example as Nylon 12 or Nylon 612 glass reinforced) is supplied to sprue  60  for passage through runner  62  and through gate  64  into the mold cavity to fill the mold cavity in surrounding relation to the tube end  10   d  and the axial core; and, following setting of the plastic materia, the upper die is removed from the lower die and the axial core  54  is removed. This molding procedure forms a connector  14  fixedly secured to the tube end portion  10   d  and having an axial bore  14   f  communicating with the open end of the tube, extending at a right angle to the central axis of the tube end portion, and conforming to the configuration of the core.  
         [0032]    The invention will be seen to provide a method and apparatus for molding a connector over the end of a multi-ply tube whereby to prevent separation of the tube plies and allow the customization of each layer of the tube to the peculiar requirements of each layer. Specifically, the outer ply may be formed of a low moisture absorption material that resists the chemical attacks peculiar to the automotive/road environment and the inner ply may be formed of a material that is stronger and has a higher melting point, whereby to accommodate the pressures and temperatures of the fluid flowing through the tube.  
         [0033]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.