Page 69 - Wire Rope News & Sling Technology - February 2020
P. 69

                                                               The inner jacket  14 may  provide a protective layer be-
                                                              tween the lubrication of the core 12 and the heat required
                                                              to impregnate the outer strands 18 with the outer jacket 16.
                                                              The inner jacket 14 material may have a melting tempera-
                                                              ture high enough to prevent displacement or removal of the
                                                              lubricant. The inner and outer jackets together form a uni-
                                                              fied jacket which may provide cushioning for the wire rope
         Figure 19: Cross-section view of part of an integrated jacket.  to absorb friction and vibration. This unified jacket acts as a
                                                              separator between the strands to prevent strand contact and
         any suitable material including one or more of polyamide   abrasion. The unification of the inner jacket 14 and the out-
         plastics, polyimide, nylons such as nylon 6, neoprene, ethyl   er jacket 16 to form an integrated jacket anchors the outer
         vinyl acetate, aramid fibers such as Kevlar™ fibers, syn-  jacket 16 within the wire rope 10.
         thetic aromatic polyamide polymer, and polymers in fiber,   The core 12 is filled with lubricant 20 prior to application
         sheet or block form such as polyethylene, polyester includ-  of the inner jacket 14 around the core 12 and prior to the
         ing liquid crystal polyester, polyethylene terephthalate,   application of the outer jacket and closing the outer strands
         polypropylene,  polyamide,  polyurethane,  polytetrafluor-  18 around the core. The lubricant 20 may be for example hot
         ethylene, polyvinyl indene, polycarbonate (and alloys) and   applied  (petroleum based) or cold applied  (asphalt based)
         polysulfone. The inner jacket 14 may for example be reticu-  or may be a synthetic lubricant such as silicones, diesters,
         lated filter foam. A metal inner jacket 14 may for example   phosphate esters, polyglycols, fluorocarbons, and polyphenyl
         be formed of fibers or foams made of tin, aluminum, copper,   ethers. In some embodiments, when the outer jacket 16 is
         steel, or iron, and may be stainless steel or contain galva-  applied, the outer jacket material may flow through pores or
         nized wires. The material of the inner jacket 14 may also   holes of the inner jacket and in and around the outer strands
         be enhanced metal, a hybrid metal material, glass or met-  18 inwardly into the inner jacket 14 through the pores until
         al  sponge,  for  example,  copper.  Use  of  strong  fibers  such   it reaches the outer surface of the core 12. The lubricant may
         as aramid fibers for the inner jacket 14 may be useful in   begin softening, melting or be forced upwards into the outer
         strengthening the pore walls to combat deterioration of the   jacket material.
         wire rope during use of the wire rope.                The  inner jacket  14  may  have  an  impermeable  floor,
           The inner jacket 14 may be permeable, such that molten   membrane or base 22 adjacent the core 12 which traps lu-
         plastic and wire rope lubrication may move through the in-  brication within the core 12, or impedes movement of lubri-
         ner  jacket  14 when  the  inner  jacket  14 is  closed  over  the   cation from the core 12. In some embodiments, the jacket
         core 12 of the wire rope. The inner jacket may be porous,   floor 22 is impermeable, as shown in figure 20, and may
         such that the inner jacket includes pores, or may form a ma-  for example be closed celled to prevent lubrication migra-
         trix, be formed by crossing fibrous material or layering grids   tion. In other embodiments, the floor 22 may be open celled
         of material, each of which may have voids such as holes or   to permit limited lubrication movement into the pores of
         openings which may allow fluid to permeate through the in-  the inner jacket. In some embodiments, the floor is slightly
         ner jacket 14. The holes of the matrix, crossed fibrous mate-  permeable, less permeable than the inner jacket 14 for ex-
         rial or layered grids may be interconnected such that liquid   ample by having small connected pores or holes to permit
         may pass through holes from one side of the matrix, crossed   small amounts of lubricant 20 to pass into the inner jacket.
         fibrous material or layered grids to the other side. The pores   In some embodiments, the floor is porous and has a differ-
         or holes may be occupied by molten or solidified plastic of the   ent porosity from that of the inner jacket 14. Lubrication of
         outer jacket 16 or core lubricant or both. The outer jacket   the core 12 helps to extend the working life of the wire rope
         16  may permeate partly or  fully  into  the  inner  jacket  14.   10. The unified jacket may provide a barrier to prevent as
         By matrix is  meant that material is interlaced to form a   much as practically possible the lubrication from escaping
         structure having spaces between the interlaced materials.   the wire rope 10. The floor 22 may be made of one or more
         By crossed fibrous material is meant that lengths of fibrous   materials, such as two different plastics, of differing poros-
         material are crossed at angles with each other to form a net-  ity and/or permeability, or the same material with portions
         work, such as for example a grid.
                                                              having different porosity and/or permeability. The floor 22
                                                              may thus have an inner portion and outer portion. One or
                                                              both of the inner portion and the outer portion of the floor
                                                              22 may be impermeable. n

         Figure 20: Cross-section view of a further embodiment of a wire rope.

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