Abstract:
The invention resides in a system and method of tensioning a net comprising a frame having at least two opposing frame members and a net extending therebetween. The net is made from material of cords of a water soluble yarn capable of high shrinkage rates when wetted with water and dried. A tensioning device may be provided along one of said frame sides for causing tensioning of localized regions in said mesh after said mesh is wetted with water. The invention further resides in a method of tensioning a net to a frame having at least two opposing frame members and the net extending therebetween such that by sizing the net larger than said frame and mounting the net onto the frame such that the border is located outside of the frame and wetting the net and allowing it to dry, the net shrinks around the frame taking up play otherwise existing prior to the wetting step.

Description:
BACKGROUND OF THE INVENTION 
   Field of the Invention 
   The present invention relates to an improvement in a netting system, and relates more particularly, to improvements in mesh netting whereby the mesh is capable of being made taut around a frame through the intermediary of a shrinkable net fiber which has a reduced length when wetted and then dried. 
   It is often desirable to maintain a net mesh in a taut condition while it is held in place on a structure. Typically, for example, in the case of a barrier net used for holding people from going over a ledge, it is desirable to maintain the person with out him or her leaning over a ledge. In prior art nets, play in the net would undesirably allow this to happen due to the net being allowed to stretch outwardly. Additionally, in the amusement field, it is common to use a mesh with wide gap openings for climbing. Often however, the nets used in this manner also have play in both the vertical and horizontal directions making them less stable and hence less desirable to be used for children. 
   Accordingly, it is an object of the invention to provide an improved shrinking net whereby the net can be assembled onto a frame and the mesh thereafter shrunk in size to allow for tensioning of the mesh relative to the frame without having to allow for longer lengths of rope which otherwise would be needed for assembly purposes. 
   It is a further object of the invention to provide a device of the aforementioned type wherein a mesh can be quickly and easily retensioned after use. 
   It is still a further object of the invention to provide a net which can be interlocked at node points or at other locking points by causing portions of the rope cord to bind on itself and/or be connected to other rope components. 
   SUMMARY OF THE INVENTION 
   The invention resides in a method and apparatus for tensioning a net which is made taut by wetting the net material such that the material shrinks when wetted and dried. More specifically, the invention resides in a net system comprising a frame having at least two opposing frame members and a net extending therebetween. The net is made from a material of cords of a water soluble yarn capable of high shrinkage rates when wetted with water and dried. A means may be provided along one of the frame sides for causing tensioning of localized regions in the net. 
   The invention further resides in a method of tensioning a net to a frame by providing the net with a border, providing the net from a material of cords of a water soluble yarn capable of high shrinkage rates when wetted with water and dried, sizing the net to be larger than the frame, mounting the net onto the frame such that the border is located outside of the frame, and wetting the net and allowing it to dry such that the net shrinks around the frame taking up play otherwise existing prior to the wetting step. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of a net embodying the invention. 
       FIG. 2  illustrates a net attached to a frame structure by means of eye bolts. 
       FIG. 3  illustrates a tensioning rod woven in the mesh at the outer border. 
       FIG. 4   a  illustrates the net installed in a frame prior to shrinkage. 
       FIG. 4   b  illustrates the net after tensioning by applying water. 
       FIG. 5  illustrates installing the net with the frame woven in the mesh, the frame could be pipe or other material. 
       FIG. 6  illustrates the net installed in the frame or structure with cable or rope. 
       FIG. 7  illustrates the net being installed to a cable using rings placed along the net border. 
       FIG. 8  illustrates a splice to a border with twisted rope. 
       FIG. 9   a  illustrates an intersection of the net. 
       FIG. 9   b  illustrates the same as  FIG. 9   a  but from the other side. 
       FIG. 10   a  illustrates a border rope looped and tucked back in itself. 
       FIG. 10   b  illustrates the rope of  FIG. 10   a  except open for further clarity. 
       FIG. 11  illustrates an intersection of the mesh with a braided rope. 
       FIG. 12  illustrates an end to end splice of a braided rope. 
       FIG. 13  illustrates an intersection of the mesh to the border. 
       FIG. 14  illustrates an end to end splice of a twisted rope. 
       FIG. 15  illustrates another end to end splice of a twisted rope. 
       FIG. 16  illustrates the material installed as a barrier, such as a fence. 
       FIG. 17  illustrates the material installed as a barrier, such as in a ball pit or children play unit. 
       FIG. 18  illustrates the material installed as shown in  FIG. 16  except the material is rachel, knottless (knitted). 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is a plan view of net  2 , consisting of an outer border  4  and tucked construction, however, cross-lock construction is also possible, and a material in addition to that disclosed in this invention can also be used, such as a core in a web rope, or a blend rope. The net  2  further is comprised of vertically extending weft members  6 ,  6  and horizontally extending warp members  8 ,  8  which intersect together with one another at intersections or nodes  10 ,  10 . The weft  6  and warp  8  members are made in whole or in part from a shrinkable material which will be discussed in greater detail later with respect to TABLES A and B below. 
   Referring now to  FIG. 2 , it should be seen that the net  2  is attached to a rigid frame  5  through the intermediary of a plurality of eyebolts  12 ,  12  which are threadedly connected within corresponding openings formed in and around the perimeter of the frame  5 . The eyelet part of the eyebolts receive the border member  4  so as to pull the net  2  in both the X and Y coordinate directions and maintain the net  2  coextensively with the plane P. 
   As seen in  FIG. 3 , in lieu of using eyebolts  12 ,  12  exclusively around the perimeter of the frame  5 , the number of eyebolts  12 ,  12  can be reduced by using a tensioning bar  22  provided along opposed side lengths of the border member  4 . In the case of the vertical sides of the border  4 , the tensioning bar  22  is threaded between the warp members  8 ,  8  and in the case of the horizontal sides of the border  4 , the tensioning bar is threaded between the weft members  6 ,  6 . The use of the tensioning bars  22 ,  22  allows for less securement points to be used between the frame and the net because the bars provide a longer contact surface against which the border  4  acts, as opposed to the single point contact which exists with the direct eyebolt connection of  FIG. 2 . In addition, it should be seen that only one of the two opposing sides requires securement through eyebolt connection, thereby allowing the other opposite side to be secured via, for example a lashing connection  24  as shown along the bottom side of the net in  FIG. 3 . 
   Referring now to  FIGS. 4   a  and  4   b , it should be seen that the net  2  of the present invention is made from a material which comprises at least portions of the weft and warp members  6  and  8  and is capable of shrinking in size once wetted. This material is better referred to as water soluble shrinkable yarns which react to wetting by reduction in length, up to the point where strain is imposed on the yarns by, for example, an outside force, such as produced by reacting against a rigid frame. 
   The tables A and B below set forth the specific characteristics of the yarns which can comprise in whole or in part, the construction of the weft warp and border members. The yarns are sold by Kuraray Co. LTD. under the tradename, Kuralon Type-T rope, through Kawashima Trading Co. Ltd., 1-6-28, Kyutaro-Machi, Chuo-ku, Osaka Japan. 
   
     
       
             
             
           
             
             
             
           
             
             
             
             
           
         
             
                 
               TABLE A 
             
             
                 
                 
             
           
           
             
                 
               1. Properties of Water Soluble Kuralon Perlohke Yarn 
             
             
                 
               In addition to the soluble property in hot water, water 
             
             
                 
               soluble Kuralon perlohke yarn has the characteristic of 
             
             
                 
               remarkable high shrinkage force in water. 
             
             
                 
               1. Characteristics of water soluble Kuralon perlohke 
             
             
                 
               yearn. 
             
           
        
         
             
                 
               (1) 
               High shrinkage ratio in wet state. 
             
             
                 
                 
               40% at free tension 
             
             
                 
               (2) 
               High shrinkage force in wet state. 
             
             
                 
                 
               In case of 10&#39;s, the shrinkage force is about 
             
             
                 
                 
               30 gr. When the both ends of yarn are fixed. 
             
             
                 
               (3) 
               High elongation at break. 
             
             
                 
               (4) 
               At wet state it shows elasticity like rubber. 
             
             
                 
               (5) 
               Abrasion resistance at wet state is a little 
             
             
                 
                 
               inferior to that of normal Kuralon perlohke yearn. 
             
             
                 
               (6) 
               Tensile strength is about half of normal Kuralon 
             
             
                 
                 
               perlohke yarn. 
             
             
                 
               (7) 
               It dissolves in water at more than 80° C. 
             
             
                 
               8) 
               Standard Properties of Kuralon Yarn. 
             
           
        
         
             
                 
               Description 
               2005P20/1T 
               2005P10/1T 
             
             
                 
               Yarn Count 
               ECC 20&#39;S 
               ECC 10&#39;S 
             
             
                 
               Dry 
             
             
                 
               Tensile Strength Kg 
               0.60 
               1.70 
             
             
                 
               Tenacity g/dr. 
               2.20 
               3.01 
             
             
                 
               Elongation % 
               15.0 
               17.0 
             
             
                 
               Wet 
             
             
                 
               Tensile Strength Kg 
               0.25 
               0.49 
             
             
                 
               Tenacity g/dr. 
               0.92 
               0.87 
             
             
                 
               Elongation % 
               102 
               108 
             
             
                 
                 
             
           
        
       
     
   
   In addition to the specific characteristics above in Table A, below listed in TABLE B, are further characteristics illustrative of the yarn material used by the present invention. 
   
     
       
             
           
             
             
           
             
             
             
           
         
             
               TABLE B 
             
             
                 
             
             
               KURALON (PVA) HIGH SHRINKAGE CORD 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
                 
               This yarn exhibits the unique behavior of fast shrinkage 
             
             
                 
               combined with a high shrinkage force when it becomes wet. 
             
             
                 
               1) Initial. Reactive Properties 
             
             
                 
               (a) Fast shrinkage: 
             
             
                 
               The time required to reach 30% shrinkage is about 7 
             
             
                 
               seconds in water at 20 Deg. C. and about 4 seconds in 
             
             
                 
               water at 30 Deg. C. 
             
             
                 
               (b) High shrinkage: 
             
             
                 
               The shrinkage ratio is about 75% in water at 20 Deg. C. 
             
             
                 
               and about 78% in water at 30 Deg. C. 
             
             
                 
               (c) High shrinkage force: 
             
             
                 
               After absorbing water, a high shrinkage force is readily 
             
             
                 
               apparent. The shrinkage force is about 170 gram (0.1 
             
             
                 
               gram/danier) in water at 30 Deg. C. after 10 seconds. 
             
             
                 
               2) Long Term Properties 
             
             
                 
               (a) High strength after shrinkage: 
             
             
                 
               Strength is about 1 gram per denier after yarn is soaked 
             
             
                 
               for 16 hours. 
             
             
                 
               (b) Elasticity can be maintained for a long time. 
             
             
                 
               3) Standard Properties 
             
           
        
         
             
                 
               Denier 
               1786 
             
             
                 
               Unit Length (meter/gram) 
               5.0 
             
             
                 
               Moisture Content (%) 
               9.2 
             
             
                 
               Strength (Kg) 
               3.88 
             
             
                 
               Tenacity (gram/dr) 
               2.17 
             
             
                 
               Elongation at Break (%) 
               26.0 
             
             
                 
                 
             
           
        
       
     
   
   As seen in  FIGS. 4   a  and  4   b , the net  2  is mounted onto a frame  5 , such that a slack S exists between it and the frame  5 . Thereafter water is applied through a hose  25  or the like and the net is caused to shrink to the point where it lies generally coextensively within the plane P. As seen in  FIG. 5 , one advantage of using a net which is capable of reducing its size is that the frame  5  can be assembled about the net taking advantage of the slack which can be provided for allowing the frame to be assembled. That is, the frame  5  conventionally will have an elbow  28  which connects with side members  29 ,  29 . Usually there will need to be some play allowed for in the net in order to allow the members  29 ,  29  to be telescopically fitted within the elbow, or vice versa. This play or slack S is thus taken up by the subsequent shrinking step as discussed previously with respect to  FIGS. 4   a  and  4   b . That is, if the net was manufactured to size, this frame would not be able to be assembled as the tubing would not be able to pull apart to allow the elbows or other fittings to telescope on the tubing/pipe. 
   In  FIG. 6 , a locating cable  30  is used in lieu of either the several eyebolts of  FIG. 2  or the rods  22  of  FIG. 3 . In this embodiment, the cable or rope is threaded through the weft and warp members immediately adjacent the border member  4 . At the corners of the frame is disposed a single eyebolt  32  which is connected to the frame at a forty-five degree angle. As seen in  FIG. 7 , in lieu of a frame, the net  2  may be connected to a tensioned cable  34  through the intermediary of rings  36  which connect around the border  4  and the cable  34 . It is noted that tensioning of the net members can be accomplished at any time once the net is mounted to the frame, including during the wetting and drying out periods. 
   Referring now to  FIG. 8 , it should be seen that the device shown in this embodiment covers a splice between a border and a twisted rope. Here, the border illustrated as  4  connects to a member  40 , which for discussion purposes, can take the form of either a weft or warp member  6  or  8 . As seen in  FIG. 8 , the member  40  is passed through one strand  42   a  of the border  4  separating the remaining members  42   b  and  42   c  in the border  4  and then is tucked under two or more strands  44   a ,  44   b  and  44   c  of itself. When wetted and allowed to dry in the manner discussed above and set forth in detail in Tables A and B, the passing through of the rope end back on itself prior to wetting causes a highly effective lock to be created. 
   Referring now to  FIGS. 9   a  and  9   b , a structure of anode  10  is shown. The node  10  in  FIG. 9   a  sows the intersection of weft and warp members  6  and  8 . Here weft member  6  passes through warp member  8  at point  50  while warp member  8  passes through weft member  6  at point  52 . When wetted and allowed to dry in the manner discussed above and set forth in detail in Tables A and B, the cross passing through of weft and warp members  6  and  8  prior to wetting causes a highly effective lock to be created. 
   The end structure shown in  FIGS. 10   a  and  10   b  illustrates end of one of the warp or weft members which is capable of being connected through a retaining rod  22  such as shown in  FIG. 3  or, alternatively, piercing through a border member as disclosed above with respect to  FIG. 8 . However, in this embodiment, it should be seen that the end  60  of the member  6 / 8  pierces back on itself through one cord of the rope at  64  and  65  after forming a loop  62  and then again pierces back on itself in an opposite 180° direction at point  66 . By way of reference, such a double back type connected is disclosed in commonly owned U.S. Pat. No. 5,622,094 entitled “Hollow Braid Net and Method of Making” issued on Apr. 22, 1997 filed in the name of John Rexroad and filed on Mar. 30, 995 as application Ser. No. 08/414,185, and which application being commonly owned with the Applicant of the present invention and is hereby incorporated reference. When wetted and allowed to dry in the manner discussed above and set forth in detail in Tables A and B, the formation of end  60  of the member  6 / 8  piercing back on itself through one cord of the rope at  64  and  65  after forming a loop  62  and then again pierces back on itself in an opposite 180° direction at point  6  prior to wetting causes a lock to be created in a highly effective manner. 
   Referring now to  FIG. 11 , it should be seen that the connection shown in  FIG. 11  is the same as shown in  FIGS. 9   a  and  9   b , except that the material used as the weft and warp members  6  ad  8  is that of a braided rope rather than a twisted one. Notwithstanding, intersection  10  is caused by the weft member  6  passing through the warp member  8  and then the warp member  8  passing through the weft member  6 . It should be further understood that the braided rope illustrated by the members  6  and  8  can be made completely of the shrinkable cord material of Tables A and B above or can be braided with strands thereof which allows the member to have a soft touch such as when formed as a composite with a microfilament material. When wetted and allowed to dry in the manner discussed above and set forth in detail in Tables A and B, the formation of intersection  10 , prior to wetting, is caused by the weft member  6  passing through the warp member  8  and then the warp member  8  passing through the weft member  6 . In this embodiment, the passed through weft and warp members  6  and  8  create a highly effective lock. 
   Referring now to  FIG. 12 , it should be seen that a splice  80  of a braided rope is shown. This splice  80  is made between two end to end pieces whose distal ends are shown at  82  and  84 . Braided rope illustrated as  86  is passed through braided rope illustrated as  88  at point  90  and braided rope  88  passes through braided rope  86  at point  92 . Thereafter, distal end  82  is turned 90° and passes through the side of braided rope  86  while distal end  84  of braided rope  86  is turned 90° and passes through the side of braided rope  88 . When wetted and allowed to dry in the manner discussed above and set forth in detail in Tables A and B, the passed through rope portions of the rope members create a highly effective lock. 
   Referring now to  FIG. 13 , it is seen that the structure shown in  FIG. 13  is the same as that shown in  FIG. 8 , except that the ends of either the warp or weft members as represented by numeral  40  are separated and then passed back in an over and under fashion into the double back portion of the rope member. When wetted and allowed to dry in the manner discussed above and set forth in detail in Tables A and B, the passing back over and under cords of the doubled back portion of the rope member effects a highly effective lock. 
   Referring now to  FIG. 14 , an end to end splice of braided rope  100  and  102  is shown. Here rope member  102  is passed between one cord member of rope  104  and rope  104  is passed under one cord member of rope  102  and the process is repeated linearly one or more times with both ends until no ends of the cord members are left dangling. When wetted and allowed to dry in the manner discussed above and set forth in detail in Tables A and B, the passing through of one rope member through the cord portion of the other rope member and vice versa effects a highly effective lock of the members. 
   As illustrated in  FIG. 15 , the splice between the twisted rope members  102  and  104  is accomplished by opening the ends of each of the members  102  and  104  and linearly splicing each end in an over-under fashion in the opposing rope. When wetted and allowed to dry in the manner discussed above and set forth in detail in Tables A and B, the splicing of each end of one rope member through that of the other and vice versa effects a highly effective lock of the members. 
   As illustrated in  FIG. 16 , the mesh  2  may be installed in a barrier, such as a fence, and is disposed between two horizontally spaced support rails  110  and  120  which, as typical, are secured by post(s)  122  to a support. The rails  120  and  110  may connect to the mesh  2  in the manner such as discussed previously with respect to  FIGS. 1–7 . 
   As illustrated in  FIG. 17 , the mesh  2 ′ is of a smaller gauge than the net  2  disclosed in  FIGS. 4 and 5 , but nevertheless is comprised in whole or in part of the water soluble yarns disclosed above in tables A and B. The mesh  2 ′ preferably is of the construction disclosed in copending U.S. patent application Ser. No. 09/012,427 filed on Jan. 22, 1998 in the name of John Rexroad and entitled “Method of Using Barrier Material and System” which application being commonly signed with the present invention and being hereby incorporated by reference. The mesh  2 ′ is installed as a barrier such as in a ball pit where children play or other children&#39;s play unit. The left side of the L-shaped frame  5  of  FIG. 17  shows a lashed in place connection  130  while the bottom run of the L-shaped frame includes plastic tie wrap connections  132 . The mesh is a knotted mesh shown in a square orientation but could also be in a diamond orientation. 
     FIG. 18  is an illustration similar to that shown in  FIG. 16  except that the material is a rachel knottless knitted mesh. 
   By the foregoing, an improved shrink net system and article has been described by way of the preferred embodiment. However, numerous modifications and substitutions may be had without departing from the spirit of the invention. Accordingly, the invention has been described by way of illustration rather than limitation.