Abstract:
A process for forcibly infusing liquid potting compound into the exposed strands of a cable prior to forming a termination. The process uses a mold that encloses the exposed strands. Potting compound is then pumped into the mold, where it runs around and through the exposed strands. A second venting passage is preferably employed, so that the liquid potting compound flows through the mold without trapping any air pockets.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates to the field of cables and ropes. More specifically, the invention comprises a process for thoroughly infusing liquid potting compound into the strands of a rope or cable prior to affixing an anchor or for other uses.  
         [0003]     2. Description of the Related Art  
         [0004]     Devices for mounting a termination on the end of a rope or cable are disclosed in detail in copending U.S. application Ser. No. 60/404973 to Campbell, which is incorporated herein by reference. Throughout this disclosure, the term “strand” will be used to describe the constituents of synthetic cables, natural-fiber cables, and ropes. Although synthetic cables are used for the illustrations, the reader should understand that the methods and devices disclosed are equally applicable to any type of stranded cable.  
         [0005]     It is often useful to affix a piece of hardware to the end of a cable. Examples of hardware would be threaded fasteners, hooks, and eyes. Such hardware will be generically referred to as an “anchor.” Anchors typically have an expanding internal passage or some type of interlocking features, such as ridges. The strands proximate the end of a cable are wetted with liquid potting compound. The wetted strands are then placed within the internal passage of the anchor. The potting compound then hardens to form a solid, thereby locking a length of strands into the anchor. The anchor, along with the contained strands and solid potting compound will be referred to as a “termination.” 
         [0006]     Those skilled in the art will know that the term “potting compound” generally refers to any liquid which can be transformed into a solid (such as by air-drying, cooling, reacting with a catalyst, etc.). Examples include thermoplastics, molten metals, thermosets, and reactive compounds (such as two-part epoxies).  
         [0007]     Two methods of infusing liquid potting compound into the strands of a cable are in common use. These are: (1) Pulling an anchor into its final position around the exposed strands and pouring the liquid potting compound into an open end of the anchor; or (2) Infusing the exposed strands with liquid potting compound, then pulling the anchor into its final position (The infusion is typically accomplished via painting on the liquid potting compound or dipping the exposed strands into a vat of liquid potting compound).  
         [0008]     Under either approach, the potting compound may fail to fully infuse the strands. Moreover, both approaches must generally be performed manually, resulting in drastic variations from termination to termination.  
         [0009]      FIG. 1  shows four cables  10  with exposed strands in varying configurations. The far left example shows core strands  12  exposed and ready for potting in an undisturbed state. Proceeding to the right, the next example shows the exposed strands being compressed to form fanned strands  14 . The next example shows the exposed strands being splayed to form conical strands  16 . The far right example shows the strands being splayed apart further to form radially fanned strands  44 . All these examples, as well as others, may be employed prior to infusing the exposed strands with liquid potting resin.  
       BRIEF SUMMARY OF THE PRESENT INVENTION  
       [0010]     The present invention comprises a process for forcibly infusing liquid potting compound into the exposed strands of a cable prior to forming a termination. The process uses a mold that encloses the exposed strands. Potting compound is then pumped into the mold, where it runs around and through the exposed strands. A second venting passage is preferably employed, so that the liquid potting compound flows through the mold without trapping any air pockets. After infusion and before the liquid potting compound hardens, the mold is opened. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0011]      FIG. 1  is an isomeric view, showing various cable strand configurations.  
         [0012]      FIG. 2  is an isometric view, showing the operation of a mold.  
         [0013]      FIG. 3  is an isometric view, showing internal passages within the mold.  
         [0014]      FIG. 4  is an isometric section view, showing the mold base.  
         [0015]      FIG. 5  is an isometric view, showing the installation of an anchor.  
         [0016]      FIG. 6  is an isometric view, showing the installation of an anchor.  
         [0017]      FIG. 7  is an isometric view, showing the mold on an assembly line.  
         [0018]      FIG. 8  is an isometric view, showing a cable clamped within a mold.  
         [0019]      FIG. 9  is an isometric view, showing an injector.  
         [0020]      FIG. 9B  is an isometric view, showing an alternate injector.  
         [0021]      FIG. 10  is an isometric section view, showing the operation of an injector.  
         [0022]      FIG. 11  is an isometric section view, showing the operation of an injector. 
     
    
     REFERENCE NUMERALS IN THE DRAWINGS  
       [0023]    
       
         
               
               
               
               
             
           
               
                   
               
               
                   
               
             
             
               
                 10 
                 cable 
                 12 
                 core strands 
               
               
                 14 
                 fanned strands 
                 16 
                 conical strands 
               
               
                 18 
                 anchor 
                 20 
                 upper mold portion 
               
               
                 22 
                 mold base 
                 24 
                 strand cavity 
               
               
                 26 
                 separator 
                 28 
                 cable cavity 
               
               
                 30 
                 strand cavity 
                 32 
                 infeed runner 
               
               
                 34 
                 liquid coupling 
                 36 
                 liquid vent 
               
               
                 38 
                 vent coupling 
                 40 
                 infused strands 
               
               
                 42 
                 anchor fork 
                 44 
                 radially fanned strands 
               
               
                 46 
                 injector 
                 48 
                 needle 
               
               
                 50 
                 injection orifice 
                 52 
                 vent 
               
               
                 54 
                 dry strands 
               
               
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION OF THE INVENTION  
       [0024]      FIG. 2  shows one embodiment of the present invention. Anchor  18  is placed on cable  10  and pulled away from the exposed end strands to the position shown. Cable  10  is then positioned between the upper mold portions  20  (In the example shown, two mold portions are used. The upper portion of the mold can also be split into three or more portions). Each upper mold portion  20  preferably includes a cable cavity  28  and a strand cavity  30 . Mold base  22  lies beneath cable  10 . The two upper mold portions  20  clamp securely together, as indicated by the arrows. This action results in cable  10  being held tightly within the internal passages in the two upper mold portions.  
         [0025]     Mold base  22  then moves upward to seal off the bottom of cable  10 . Those skilled in the art will realize that the type of mold shown is but one among many. The mold could split in other ways, move together in different ways, etc.  
         [0026]     Once the mold closes, cable  10  is held securely within the internal passages.  FIG. 3  is a sectional view of one of the two upper mold portions  20 . The reader will observe that infeed runner  32  connects liquid coupling  34  with strand cavity  30 . When clamped in place, preferably pressurized liquid potting compound is forced through infeed runner  32  where it emerges in and around the exposed strands of cable  10 . Cable cavity  28  is clamped securely around the rest of cable  10 , thereby preventing the liquid potting compound from diffusing upward beyond the exposed end strands. As an alternative, a fairly loose fit can be provided around cable  10  so that entrapped air can vent past cable  10 . The second upper molding portion can be equipped with a corresponding infeed runner. Additional infeed runners could also be provided in the mold base. An infeed runner could be placed at virtually any location and in any orientation within strand cavity  30 .  
         [0027]      FIG. 4  is an isometric section view of mold base  22 . Its upper surface opens into strand cavity  24  (A flat upper surface having no recess can also be used). A conically shaped separator  26  may be provided in the middle in order to splay the exposed strands of the cable when mold base  22  is moved up into position. Mold base  22  is preferably equipped with one or more liquid vents  36 . These connect to vent coupling  38 . In operation, the mold parts are clamped together to form the enclosed strand cavity  30 . Liquid potting compound is then forced under pressure into the mold through infeed runners  32 . Liquid vents  36  allow air within the mold cavity to escape. Eventually, liquid potting compound completely fills the cavity and flows out through liquid vents  36 . A vacuum may be applied to vent coupling  38  in order to promote faster flow or more complete liquid potting compound infusion.  
         [0028]     As an alternative, the infeed runners and liquid vents can be reversed so that the liquid potting compound flows from the bottom to the top. Vacuum and pressure can also be used interchangeably to create the desired flow. Although the runners and vents have been shown as circular, those skilled in the art will know that they could also be made with an oval cross section, a square cross section, or any other desired shape.  
         [0029]      FIG. 5  shows cable  10  after its end strands have been infused with liquid potting compound within the mold. The end strands are now denoted as infused strands  40 . Anchor  18  is then moved down in the direction shown until it encloses the infused end strands (or otherwise mechanically interlocks). Anchor  18  is shown in its final position in  FIG. 6 . It remains in this position while the liquid potting compound hardens into a solid, thereby forming a completed termination. As an alternative, anchor  18  can be slid into position from the opposite end of the cable after the liquid potting compound is applied.  
         [0030]      FIG. 7  shows the application of the devices and processes disclosed to an assembly line. A series of cables  10 —with anchors  18  in an appropriate position, are sequentially fed along the line in the direction indicated by the arrow. The middle cable  10  is set to be clamped within the mold components. Its exposed end strands will then be infused with liquid potting compound. The cable  10  immediately to the right of the middle cable  10  has just exited the mold. Its end strands have been infused with liquid potting compound. They are thus denoted as infused strands  40 .  
         [0031]     As cable  10  moves further down the line, anchor fork  42  (or other suitable devices, whether automatic or manual), may be employed to pull anchor  18  into the appropriate position before the liquid potting compound hardens. Similar devices can be employed to retain the anchors in the appropriate positions throughout the process.  
         [0032]     The same process can be applied where a mold is substituted for anchor  18 . In other words, a mold can be pulled in place over the strands while they are allowed to set. This mold can then be removed and the strands placed in a separate anchor.  
         [0033]     Those skilled in the art will realize that the internal cavities within the mold components, as well as the infeed runners and vents, can be made in virtually any shape. Multi-cavity molds can also be used to increase the feed rates. Returning to  FIG. 1 , the reader will appreciate that the mold can be configured to clamp the fibers in any one of the four configurations shown (as well as others). As an example,  FIG. 8  shows a mold having a strand cavity  30  shaped to deform the strands into radially fanned strands  44  (The cable is shown sectioned to aid visualization). A separator  26  is also used.  
         [0034]     The injection process can even be modified to infuse the liquid potting compound from the center of the exposed strands outward.  FIG. 9  shows injector  46 . Needle  48  extends from its lower surface. Injection orifice  50  passes through needle  48  (The orifice can assume a variety of shapes). The lower surface also opens into a pair of vents  52 .  FIG. 10  shows injector  46  in a section view. Injection orifice  50  is connected to a supply of liquid potting compound (not shown). Vents  52  can be vented to the surrounding air. In operation, a mold is placed around the dry exposed strands on the end of a cable. For the example shown, an anchor  18  is actually used as the mold (Split molds such as shown previously could also be used). The anchor has an expanding internal passage which serves as a strand cavity. It also has an open end. Injector  46  is moved toward the exposed strands as indicated.  
         [0035]      FIG. 11  shows injector  46  mated to anchor  18 . The lower surface of injector  46  is actually pressed against the upper surface of anchor  18  to form a sealing surface. Needle  48  protrudes down into the exposed strands. Liquid potting compound is then infused through injection orifice  50 . It flows out through the strands toward the two vents  52 , thereby completely infusing the strands within the anchor&#39;s internal passage. Once the infusion is completed, injector  46  is withdrawn. The liquid potting compound then hardens to complete the termination.  
         [0036]     Those skilled in the art will realize that injector  46  can take many forms, including breaking the injector into two or more pieces (like a mold). Needle  48  is optional. The injection could be accomplished via forcing the liquid potting compound through a simple hole. Such an alternate embodiment is shown in  FIG. 9B . Likewise, the seal between injector  46  and anchor  18  can be acheived using many methods, including an O-ring or interlocking threads. With the anchor itself forming the mold, it may be advisable to add infeed runners or vents to the anchor. These features could take many shapes.  
         [0037]     As stated previously, a split mold can be used in the place of anchor  18 . In such a case, the anchor would be added after the infusion process is complete.  
         [0038]     Throughout the preceding disclosure, terms referring to the orientation of the parts have been used (“upper”, “lower”, etc.). Those skilled in the art will realize that the orientation of the components has no significant impact on the operation of the devices. These terms referred only to the orientations shown in the views, and should not be taken as limiting the scope of the invention.  
         [0039]     Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention.