Abstract:
A lifting sling and a lifting grommet are disclosed which can be fabricated of a high tensile strength polymeric material, preferably a woven polymer such as liquid crystal polymer fibers, that are woven in a rope or cable configuration. The apparatus features an elongated woven material length of cable that is spliced. Plastic, preferably polyurethane spring cut tube sleeves are positioned as a grip on the splices to allow for handling in the field without concern for the splice becoming disassembled or undone. The sling and grommet of the present invention can each be provided with a clear cover spring cut tube that serves as a flexible protective cover for minimizing abrasion and maintaining the slings appearance.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Priority of U.S. Provisional Patent Application Ser. No. 60/470,695, filed May 15, 2003, incorporated herein by reference, is hereby claimed. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable 
     REFERENCE TO A “MICROFICHE APPENDIX” 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to rigging, namely slings and grommets that are used during heavy lifting and more particularly to a heavy lifting system that includes a specially configured sling and grommet of improved construction wherein an elongated sling member includes an elongated woven portion having first and second ends and a central passageway surrounded by the woven material, and wherein one or more flexible sleeves can be optionally fitted to the elongated sling member at its loop portions and at its connecting portions. If the tensile material is one large circular loop, it is referred to as a grommet. These elongated sleeves are preferably of a spiral construction that can be easily installed in the field once a sling length is selected, and function to prevent abrasion during use and to prevent slippage at the splice. The grommet has a similar flexible sleeve fitted to splices of the grommet. 
     2. General Background of the Invention 
     In the lifting of very heavy items, lifting harnesses are typically employed which comprise an elongated length of tensile material having loops at each end. These slings have commonly taken the form of wire rope having looped ends. In the case of wire rope, the looped ends are often secured using a crimp or band. Once the sling is constructed, its length is “fixed”. A user must plan the lift in advance by selecting slings of a desired fixed length. 
     Polymeric and plastic material has been used to construct slings and grommets. A grommet is a sling that is circular in shape so that the user simply hooks or grabs the entire sling rather than a looped end portion. New England Ropes publishes a “Splicing Guide” that discloses various rope splicing techniques. 
     One of the problems with slings and grommets of either metallic or plastic construction is that of field adjusting the sling length. Wire rope slings are not adjustable. Plastic and polymeric slings are typically sewn to form the loops so that they are not easily adjustable on the job site. 
     One polymeric material that has a high tensile strength is liquid crystal polymer fiber. One brand that is manufactured by Celanese Acetate LLC is sold under the trademark Vectran®. Celanese literature states that Celanese has contracted aerospace and rope manufacturers to conduct pin diameter tests on Vectran® braid and wire rope respectively. The same literature shows a braid test using a braid having two eyes at the ends. However, this type of “test” braid would quickly become disassembled and or slip in routine use as a sling in a construction environment. 
     When rigging for many different lifts during a day, a rigger desirably wants a sling that is adjustable so that the length can be varied to fit the particular item being lifted. Further, slings should not slip or become disassembled on the job. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an improved lifting system that features a specially configured lifting sling that is comprised of an elongated sling member that includes an elongated woven portion having first and second ends and a central passageway surrounded by woven material. 
     With the present invention, first and second connections join each end of the woven portion at the central passageway and at spaced apart positions to form eyes or loops (see  FIG. 1 ). One or more flexible spiral cut sleeves can be fitted to the sling, preferably at the eyes or loops. Each sleeve defines an interface between the loop and a lifting member that engages the eye in the preferred embodiment. 
     The lifting eyes can also be used to be fitted to the woven portion to prevent or discourage slippage after the sling is constructed. 
     The flexible sleeve can include a spirally configured portion. The flexible sleeve can be a polymeric or polyurethane member, preferably including liquid crystal polymer fibers. 
     The present invention can be constructed in the form of a grommet or circular sling that does not have loops. 
     The present invention is easy to fabricate, can be reused at different lengths, and is easy to reuse in a different form (sling, grommet, etc.). The present invention features a sleeve which is preferably in the form of a polyurethane, spiral cut or spring cut tube. This sleeve serves as a grip or compression on the splice to allow for handling in the field without having any concern that the splice will come apart. 
     The sleeve is preferably removable so it can be reused with different slings of different lengths from day to day. 
     A polyurethane spring cut sleeve or tube also serves as a flexible thimble at the “bite” or eye of the sling to prevent abrasion and rapid wear at these critical points. 
     A polyurethane spiral cut or spring-cut clear cover can also be used over the entire length of the sling that is otherwise not covered as a flexible protective cover, minimizing abrasion and keeping the sling intact. 
     The present invention features an insert that is preferably of straight fiber filler (preferably liquid crystal polymer fiber) for increasing the sling strength at the bite point in a grommet opposite the splice entry point. 
     This straight insert section of fiber filler increases the sling strength at the bite point in a doubled over eye and eye sling when positioned opposite the two eyes (see  FIG. 2 ). 
     One embodiment of the present invention is a grommet (see  FIG. 3 ). In one embodiment, a preformed spiral cut thimble offers additional protection at the sling bite while still being removable (see  FIGS. 16-18 ). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
         FIG. 1  is a front, elevational view of the preferred embodiment of the apparatus of the present invention; 
         FIG. 2  is a front, elevational view of the preferred embodiment of the apparatus of the present invention showing the sling in a doubled configuration; 
         FIG. 3  is a front, elevational view of a second embodiment of the apparatus of the present invention showing a grommet; 
         FIG. 4  is a front, elevational view of a portion of the preferred embodiment of the apparatus of the present invention shown prior to formation in sling or grommet form; 
         FIG. 5  is a schematic, front, elevational view showing a portion of the apparatus of the present invention during forming; 
         FIG. 6  is a front, elevational view of the preferred embodiment of the apparatus of the present invention showing a sling during forming; 
         FIG. 7  is a front, elevation, fragmentary view of the preferred embodiment of the apparatus of the present invention; 
         FIG. 8  is a front view of the insert portion of the preferred embodiment of the apparatus of the present invention, an optional component; 
         FIG. 9  is a sectional view taken along lines  9 - 9  of  FIG. 7 ; 
         FIG. 10  is a sectional view taken along lines  10 - 10  of  FIG. 4 ; 
         FIG. 11  is a sectional view taken along lines  11 - 11  of  FIG. 5 ; 
         FIG. 12  is a perspective, fragmentary view of the preferred embodiment of the apparatus of the present invention showing the spiral cut tube prior to cutting; 
         FIG. 13  is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention showing the spiral cut sleeve portion thereof; 
         FIG. 14  is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention illustrating the placement of the insert portion into the bite area; 
         FIG. 15  is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention showing two spiral cut sleeves in position at the bite area and at the splice area; 
         FIG. 16  is a fragmentary perspective view of the preferred embodiment of the apparatus of the present invention showing the preformed thimble with spiral cut end portions thereof; 
         FIG. 17  is a sectional view taken along lines  17 - 17  of  FIG. 16 ; 
         FIG. 18  is a fragmentary, perspective view of the preferred embodiment of the apparatus of the present invention illustrating the preformed spiral cut thimble portion thereof; 
         FIG. 19  is a front, elevational, schematic view illustrating the beginning of construction of the grommet embodiment; 
         FIG. 20  is a front elevation, schematic view illustrating a further construction of the grommet embodiment; 
         FIG. 21  is yet another front, elevational, schematic view illustrating construction of the grommet embodiment; 
         FIG. 22  is a front, elevation schematic view illustrating the grommet embodiment and illustrating placement of spiral cut sleeves at the bite and splice areas; and 
         FIGS. 23-25  are front elevational views of the preferred embodiment of the apparatus of the present invention showing a sling during forming, and wherein a first spiral cut sleeve completely covers the lifting eye and a section of the sling next to the lifting eye, and a second spiral sleeve covers the first spiral sleeve on the sling next to the lifting eye. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 and 2  show generally the preferred embodiment of the apparatus of the present invention designated generally by the numeral  10 . Lifting sling  10  includes a sling member  11  (preferably polymeric, more preferably liquid crystal polymer) that can be provided with a pair of spaced apart lifting eyes  16 ,  18  as shown in  FIGS. 1 and 2 . 
     In  FIG. 2 , the sling member  11  is much longer and is doubled so that both of the lifting eyes  16 ,  18  are positioned in side by side relationship and supported by hook  65  attached to crane lifting line  64 . In  FIG. 1 , a single strand configuration for sling  10  is shown with the lifting eye  16  being attached to hook  65 . The lower lifting eye  18  is attached to shackle  21  which is affixed to both lifting eye  18  and load  20  to be lifted. 
     Lifting eye  16  provides an opening  17  that enables it to be attached to hook  65  of a crane and its lifting line  64 . Similarly, eye  18  has an opening  19  that enables it to be attached to an object to be lifted such as load  20  or to a shackle  21  that forms an interface between load  20  and eye  18 . 
     The sling member  11  is shown in  FIG. 4  before assembly. One of the features of the present invention is that a sling can be constructed and used in the field of a selective length because the sling length can be changed at any time by the user. This is accomplished by beginning with a sling member  11  that is an elongated member comprised of a woven portion  27  having end portions  12 ,  14  as shown in  FIG. 4 . The end portion  12  is preferably contained with band  13  to prevent unraveling. Similarly, a band  15  is provided at end portion  14 . 
     In the preferred embodiment, the woven material  27  that comprises sling member  11  is a liquid crystal polymer (LCP) fiber material that is very strong. Such a product is manufactured by Celanese Acetate LLC under the trademark Vectran®. 
     One of the problems with liquid crystal polymer material is that it typically has a tendency to abraid when used in the hostile environment of a lifting sling in an industrial plant. when spliced, this material can carry a substantial load so long as the splice is loaded and maintained in tension, such as in a controlled setting (eg. lab). However, in an industrial plant or construction environment, slings of this type are handled with little care. They can be, for example, thrown on the ground, rolled over by heavy vehicles, subjected to dragging across dirt, gravel, sand, etc. In such a hostile environment, the splice can easily shift positions or become completely disassembled. 
     The present invention provides a plurality of spring cut or spiral cut sleeves such as sleeves  22 ,  23 . These spiral cut sleeves  22 ,  23  include sleeves  22  that are configured to be positioned at the bite area  34  of a lifting eye  16  or  18  as shown in  FIGS. 1-13  and  15 . 
     The spiral cut sleeves  22 ,  23  are also provided at the area of splices, those sleeves being designated by the numeral  23 . For example, in  FIG. 1 , the sling  10  is provided with two spiral cut sleeves  22  at the bite area  34  of both lifting eyes  16  and  18 . Additionally, the sling  10  in  FIG. 1  is provided with two spiral cut sleeves  23  that are provided at the splice area next to each of the lifting eyes  16  and  18 . 
     In  FIG. 2 , the elongated sleeve  10  is of the same configuration generally as the sling of  FIG. 1 . However, in  FIG. 2 , there are five spiral cut sleeves provided. There are two spiral cut sleeves  23  at the splice areas next to the lifting eyes  16  and  18 . There are three spiral cut sleeves  22  placed at the bite areas. These include the bite area  34  of each lifting eye  16 ,  18  and the bite area  64  that is positioned about midway between the lifting eyes  16 ,  18  as shown in  FIG. 2 . 
     For the grommet  70  of  FIG. 3 , there are four spiral cut sleeves provided. These include the spiral cut sleeves  22  at the bite areas of the grommet  70  and the spiral cut sleeves  23  provided at the splice areas of the grommet  70 . 
       FIGS. 5 ,  6  and  7  illustrate assembly of the lifting sling  10  of the present invention by a user in the field. The apparatus of the present invention enables a user such as an engineer, crane operator, construction foreman or the like to construct a sling  10  of any desired length and to adjust the length of the sleeve in the field. In  FIG. 6 , a splicing tool  28  is attached to end portion  14  of sling member  11 . A user&#39;s hands  24 ,  25  in  FIG. 5  are moved together in the direction of arrows  26 , in order to thicken or expand a portion of the sling member  11  to produce the expanded section  30  shown in  FIGS. 5 and 6 . The expanded section  30  is also shown in a sectional view of  FIG. 11 .  FIG. 11  should be compared with  FIG. 10 , showing the normal cross sectional configuration of sling member  11  and specifically its woven portion  27 . 
     The woven portion  27  can be comprised of a plurality of for example, twelve (12) plies surrounding a central passageway  33 . In  FIG. 11 , the passageway  33  has been greatly enlarged as shown to accommodate splicing tool  28  and end portion  14  of sling member  11 . Arrow  29  in  FIG. 6  schematically illustrates the placement of splicing tool  28  into opening  31  in expanded portion  30  of sling member  11 . The splicing tool  28  is then routed a desired distance away from the opening  31  in the direction of arrow  29 . 
     In  FIG. 6 , position arrow  32  indicates schematically the terminal location for final placement of the end  14  portion of sling member  11  to complete the splice. It should be understood that this type of rope splice in general is known, being referred to and illustrated for example in the New England Ropes Splicing Guide has a single braid eye splice. The problem encountered in the lifting art, is that the use of such a single braid eye splice with very strong polymeric fibers such as liquid crystal polymer produces a sling that will easily slip or disassemble itself during field use and under hostile conditions found in industrial plants, construction sites, fabrication yards, etc. Therefore, there has not been a high strength, high tensile sling of liquid crystal polymer construction that could be field assembled, field adjusted, and still maintain integrity and strength during use. 
     With the present invention, the splice that extends between opening  31  and position  32  is covered with spiral cut sleeve  23  as shown in  FIG. 7 . Arrow  66  in  FIG. 7  schematically illustrates the placement of spiral cut sleeve  23  upon the splice area that extends between opening  31  and position  32 . The user simply continuously winds the spiral cut sleeve  23  upon the splice area as shown in  FIG. 7  as indicated by the arrow  66 . 
     The construction of a particular spiral cut sleeve  22  or  23  can be seen in  FIGS. 12-13 . In  FIG. 12 , each spiral cut sleeve  22  or  23  is first construction of a tube  35  having a tube bore  36  and a tube wall  37 . Tube  35  is preferably of a polyurethane material. The dotted line  38  in  FIG. 12  indicates the cut line for cutting tube  35  to produce spiral cut sleeves  22  or  23 . 
     In  FIGS. 12 and 13 , the tube  35  can be any desired wall thickness for tube wall  37  and any desired bore diameter for bore  36  can be provided. By changing the bore diameter  36  and/or the thickness of wall  37 , a desired flexibility can be provided for spiral cut sleeve  22  or  23 . Similarly, by changing the bore diameter  36  or the wall thickness  37 , a desired compression can be obtained for applying compression at the splice area of any sling that is constructed according to the method and apparatus of the present invention. 
     In  FIG. 9 , the compressive loading of the splice area is shown with the sleeve  23  tightly compacting the end portion  14  of sling member  11  within the central passageway  33  of a selected section of sling member  11 . After the sleeve  35  is cut, a leading and trailing edge  39 ,  40  is defined as shown in  FIG. 13  for the spiral cut sleeves  22 ,  23 . These edges  39 ,  40  can be placed in a spaced apart orientation as shown in  FIGS. 14 and 15  or can be placed very close together as shown with the spiral cut sleeves  23  in  FIG. 1 . 
     In  FIGS. 14 and 15 , an insert  41  is shown for thickening the sling  10  of the present invention or the grommet  70  of the present invention as selected by a user. The insert  41  is shown more particularly in  FIG. 8  as being comprised of a plurality of aligned fibers  42 , such as liquid crystal polymer fibers. The fibers  42  are held together in an aligned group using a plurality of bands  43  for example. It has been found that the insert  41  provides an enhancement to the load capacity of sling  10  or grommet  11  when maintained in an unwoven configuration as shown in  FIGS. 8 and 14 , the unwoven fibers  42  being simply placed side by side in an aligned configuration and held together with bands  43 . 
     In  FIG. 14 , insert  41  is shown being inserted into sling member  11  at lifting eye  18 , beginning at opening  45  and exiting at opening  46 . Arrows  44  in  FIG. 14  illustrate the path that is traveled by splicing tool  28  and the attached insert  41 . Arrow  47  in  FIG. 14  schematically illustrates the exit of splicing tool  28  from opening  46 . Once the insert  41  is placed within a selected area such as the bite area of a sling  10  as shown in  FIG. 15 , a spiral cut sleeve  22 , or one of the thimbles shown in  FIGS. 16-18 , can be placed over the area that has become thickened by the presence of the insert  41 . This thickened area increases sling strength at the bite point and bite area. 
     In  FIGS. 16-18 , other configurations for reinforcement of the bite area  34  are shown. In  FIG. 16 , thimble  48  includes a solid (eg. molded) portion  49  having a U shaped cross section as shown in  FIG. 17 . The solid portion  49  has a U shaped wall  52  that can be integrally connected to the spiral cut ends  50 ,  51  such as by molding. In  FIG. 17 , the thimble  48  includes solid portion  49  having a concavity  53  and a convex outer surface  54 . The concavity  53  is occupied by a portion of the lifting eye  18  at the bite area  34 . The solid portion  49  has edges  55 ,  56  as shown in  FIGS. 16 and 17 . A pair of spiral cut sleeve end portions  50 ,  51  are attached (eg. integrally molded) to solid portion  49  as shown in  FIG. 16 . 
     In  FIG. 18 , a spiral cut thimble sleeve  57  is shown that is formed by molding, for example. This differs from the embodiment of  FIGS. 12 and 13  for the sleeves  22 ,  23  in that the spiral cut thimble  57  is formed in the shape shown in  FIG. 18 , designed to track the shape of a lifting eye  16  or  18 . The spiral cut thimble  57  is thus adapted to be placed at the bite area  34  of a lifting eye  16  or  18  or at the bite area of a grommet  70 . The spiral cut thimble  57  has an outer wall  58  that is segmented, having leading and trailing edges  60 ,  61 , a bore  59 , and ends  62 ,  63 . 
     In  FIGS. 23-25 , a variation is disclosed for the placement of the spiral cut sleeves  22 ,  23 . In  FIG. 23 , the spiral cut sleeve  23  is first being shown applied to a lifting eye  18 .  FIGS. 22 and 23  illustrate that the lifting eye  18  is completely covered with spiral cut sleeve  23 . In  FIGS. 24 and 25 , a second spiral cut sleeve  23  is applied over the first spiral cut sleeve  22  but only at a position directly above the lifting eye  18  as shown i  FIG. 25 . 
     In  FIGS. 19-22 , the construction of grommet  70  is shown beginning with an elongated grommet member  68  having end portions  69 ,  71 . An entry point  72  is selected for placement of splicing tool  73  thereinto. Arrow  74  indicates schematically the insertion of splicing tool  73  into the central passageway of grommet member  68 . 
     The cross sectional configuration of the grommet member  68  can be identical to that of the sling member  11  shown in  FIGS. 10 and 11 . In  FIG. 20 , the numeral  75  indicates the position of end  71  after being embedded in the passageway of grommet member  68 . In  FIG. 21 , the splicing tool  73  is attached to end  69  and inserted into opening  76  as indicated by arrow  77  in  FIG. 21 . 
     In  FIG. 22 , the end  69  of grommet member  68  is embedded to the position  78  shown in  FIG. 22 . In order to complete the grommet  70 , spiral cut sleeves  23  are placed over each of the splice areas as shown in  FIG. 22 . The areas to be attached to a lifting crane or a load to be lifted are covered with spiral cut sleeves  23  or either of the thimbles  48 ,  57  shown in  FIGS. 16-18 . 
     The completed grommet  70  is shown in  FIG. 3  being attached to hook  65  attached to lifting lines  64  at one end. The other end of grommet  70  attaches at shackle  21  to load  20 . 
     PARTS LIST 
     The following is a list of parts and materials suitable for use in the present invention: 
     
       
         
               
               
             
           
               
                   
               
               
                 Part Number 
                 Description 
               
               
                   
               
             
             
               
                 10 
                 lifting sling 
               
               
                 11 
                 sling member 
               
               
                 12 
                 first end 
               
               
                 13 
                 band 
               
               
                 14 
                 second end 
               
               
                 15 
                 band 
               
               
                 16 
                 lifting eye 
               
               
                 17 
                 opening 
               
               
                 18 
                 lifting eye 
               
               
                 19 
                 opening 
               
               
                 20 
                 load 
               
               
                 21 
                 shackle 
               
               
                 22 
                 spiral cut sleeve 
               
               
                 23 
                 spiral cut sleeve 
               
               
                 24 
                 user&#39;s hand 
               
               
                 25 
                 user&#39;s hand 
               
               
                 26 
                 arrow 
               
               
                 27 
                 woven portion 
               
               
                 28 
                 splicing tool 
               
               
                 29 
                 arrow 
               
               
                 30 
                 expanded section 
               
               
                 31 
                 opening 
               
               
                 32 
                 position 
               
               
                 33 
                 central passageway 
               
               
                 34 
                 bite area 
               
               
                 35 
                 tube 
               
               
                 36 
                 tube bore 
               
               
                 37 
                 tube wall 
               
               
                 38 
                 cut line 
               
               
                 39 
                 edge 
               
               
                 40 
                 edge 
               
               
                 41 
                 insert 
               
               
                 42 
                 fiber 
               
               
                 43 
                 band 
               
               
                 44 
                 arrow 
               
               
                 45 
                 opening 
               
               
                 46 
                 opening 
               
               
                 47 
                 arrow 
               
               
                 48 
                 thimble 
               
               
                 49 
                 solid portion 
               
               
                 50 
                 spiral cut end 
               
               
                 51 
                 spiral cut end 
               
               
                 52 
                 ushaped wall 
               
               
                 53 
                 concavity 
               
               
                 54 
                 convex surface 
               
               
                 55 
                 edge 
               
               
                 56 
                 edge 
               
               
                 57 
                 spiral cut thimble 
               
               
                 58 
                 outer wall 
               
               
                 59 
                 bore 
               
               
                 60 
                 edge 
               
               
                 61 
                 edge 
               
               
                 62 
                 end 
               
               
                 63 
                 end 
               
               
                 64 
                 lifting line 
               
               
                 65 
                 lifting hook 
               
               
                 66 
                 arrow 
               
               
                 67 
                 bite area 
               
               
                 68 
                 grommet member 
               
               
                 69 
                 end portion 
               
               
                 70 
                 grommet 
               
               
                 71 
                 end portion 
               
               
                 72 
                 entry 
               
               
                 73 
                 splice tool 
               
               
                 74 
                 arrow 
               
               
                 75 
                 position 
               
               
                 76 
                 opening 
               
               
                 77 
                 arrow 
               
               
                 78 
                 position 
               
               
                   
               
             
          
         
       
     
     The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.