Abstract:
An interwoven belting fabric for use in conveyors, including treadmills, is constructed of a dual layer of weft yarns comprising adjacent couplets, a plurality of middle warp yarns, and a plurality of binder warp yarns. Each middle warp yarn is heat set under tension so that it is sufficiently straight and inelastic to bear loads under tension without twisting or stretching.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates to belts for use on conveyors, treadmills, and the like, and more particularly to an interwoven belt fabric for use in such belts.  
         [0003]     2. Background Art  
         [0004]     Endless belts are typically formed by joining opposite ends of a section of belt material and used in a number of different applications. One commonly known application for such endless belts is in physical exercise equipment such as treadmills, as well as in various material handling applications such as check-out counters in stores, and the like.  
         [0005]     In a treadmill used for physical exercise, a motor driven belt extends over a flat running deck. The typical treadmill belt consists of woven material provided with a top layer of polyvinyl chloride or the like. Since the woven belt material forming the bottom surface of the woven belt is forced into contact with the top surface of the running deck by the weight of the person using the exercise equipment, the belt preferably has specific characteristics such that the belt has a low coefficient of friction with the deck, has a consistent stability when under load, produces a minimum noise and provides enhanced performance with the addition of lubricants between the surface of the deck and the belt.  
         [0006]     The type of fabric used, to a very large extent, determines certain characteristics of the belt, such as the coefficient of friction, ability to dissipate heat, ability to absorb lubricants, stability, and noise generation. Typically, in prior art belts, the quieter belts have a higher coefficient of friction and belts made with a multi-filament warp yarns (i.e., yarns with long staple lengths) tend to have a lower coefficient of friction than spun warp yarns (i.e., yarns with short staple lengths). Furthermore, treadmill belts made with a typical plain weave fabric using multi-filament warp yarns and monofilament fibers in the weft generally have a relatively low coefficient of friction, but generate a relatively high level of noise.  
         [0007]     In a typical prior art plain weave fabric, multi-filament warp yarn is alternately woven over and under a series of adjacently disposed monofilament weft fibers. In one prior art belt fabric, referred to as a one-by-three whisper weave-broken twill fabric, a multi-filament warp extends over one monofilament weft and under three monofilament controller is manually operable from a location remote from the latches such that the latches are manually and remotely controlled  
         [0008]     In another embodiment, the present invention is a fingerboard having at least one fingerboard row for storing a plurality of threaded tubulars. A plurality of latches are connected to the at least one fingerboard row, wherein each of the plurality of latches is biased into a locked position and movable between the locked position and an unlocked position. A piston having an elongated rod is slidingly engaged with a casing, wherein the casing has a plurality of exhaust ports in fluid connection therewith, and wherein each of the plurality of exhaust ports is connected to a corresponding one of the plurality of latches. An air source is in fluid connection with the casing, wherein the elongated rod is movable between a fully retracted position and a plurality of extended positions corresponding to each of the plurality of exhaust ports, wherein in the fully retracted position each of the exhaust ports are covered by the elongated rod, such that air from the air source cannot flow therethrough allowing each of the corresponding latches to be biased in the locked position, and wherein in each successive one of the plurality of extended positions a successive one of the plurality of exhaust ports is uncovered such that air flows therethrough to force a successive one of the corresponding latches to move from the locked position to the unlocked position.  
         [0009]     In yet another embodiment, the present invention is a fingerboard having at least one fingerboard row for storing a plurality of threaded tubulars. A plurality of latches are connected to the at least one fingerboard row, wherein each of the plurality of latches is biased into a locked position and movable between the locked position and an unlocked position. A piston having an elongated rod is slidingly engaged with a casing, wherein the casing has a plurality of exhaust ports in fluid connection therewith. Each of a plurality of conduits fluidly connects one of the plurality of exhaust ports to a corresponding one of the plurality of latches. An air source is in fluid connection with the casing, wherein the elongated rod is movable between a fully retracted position and a plurality of extended positions corresponding to each of the plurality of exhaust ports, wherein in the fully retracted position each of the exhaust ports are covered by the elongated rod, such that air from the air source cannot flow therethrough allowing each of the corresponding latches to be biased in the locked position, and wherein in each successive one of the plurality of extended positions a successive one of the plurality of exhaust ports is uncovered such that air flows therethrough to force a successive one of the corresponding latches to move from the locked position to the unlocked position. A piston guide is connected to the piston and has a plurality of stop positions, wherein each of the plurality of stop positions corresponds to one of the plurality of extended positions of the elongated rod.  
         [0010]     In still yet another embodiment, the present invention is a method of storing a plurality of threaded tubulars in a fingerboard including providing a fingerboard row for storing the plurality of threaded tubulars; providing a casing having a plurality of exhaust wefts. Another prior art belt fabric, referred to as an interwoven fabric, has a layer of upper monofilament weft yarns and a layer of lower monofilament weft yarns. The two layers are separated by a light denier yarn and each of a plurality of multi-filament warp binder yarns extend under one of the lower monofilament weft yarns and over an adjacent upper monofilament weft yarn.  
         [0011]     A problem with the prior art one-ply plain weave and whisper weave belts, when used in a treadmill belt or the like, is that they lack the desired stiffness required under various loads and at various speeds. When such materials are used, a two ply belt is typically required to obtain the desired stiffness. However, two ply belts are considerably more expensive to produce than single ply belts. For example, the manufacture of a two-layer belt may require as many as five passes through a belt making machine, one for the inner layer, one for the cover and three for the glue layers.  
         [0012]     Prior art interwoven fabrics are generally considered to be undesirable for use in belts, because belts made of such fabrics are relatively noisy and the fabric typically has to be saturated with a plastic material to prevent the weft yarns from migrating out of the side of the belt.  
         [0013]     Treadmill belts typically are operated at a higher speed than standard conveyer belts used for material handling and are typically subjected to greater concentrated loads as a result of the running action of a person on the belt. Hence, treadmill belts must be relatively stiff, particularly in the lateral direction. Such stiffness is generally obtained in prior art belts by making a thicker one-ply belt or by using two-ply belts.  
         [0014]     Prior art one-ply and two-ply belts are comprised of a single layer of fabric or a double layer of a fabric, respectively, and a top cover layer of rubber or vinyl, or the like. The majority of such belts use monofilament yarns in their weft since material of that construction typically provides a relatively stable belt that lays flat, does not bunch up, and tracks straight. Generally, thicker belts are more stable than thinner belts and two-ply belts are more stable than one-ply belts.  
         [0015]     However, thicker belts are typically relatively heavy and stiff in the longitudinal direction, thereby presenting a relatively higher load to the electric motor used to drive the belt. The higher load to the motor requires that a larger, more expensive motor be used which typically draws more current, all of which adds to the cost of the equipment and its operation. Therefore, a light weight, highly flexible, low friction belt is clearly desirable for applications such as treadmills. Furthermore, treadmill belts are subjected to much greater speed variations than standard conveyer belts. Hence, a belt for use in a treadmill application must be stable at high speeds as well as at low speeds.  
         [0016]     To reduce power consumption and the generation of heat, it is desirable to reduce friction between the belt and the running deck. Hence, belts with a low coefficient of friction are preferred. Additionally, lubricants are often applied between the belt and the running deck to further reduce friction. A lubricant such as paraffin wax, Teflon®, or solventless silicone is commonly used to reduce friction between the belt and the deck. In order for a lubricant to be used effectively, however, the belt must be able to absorb a certain amount of the lubricant. Certain prior art plain weave and interwoven belts having monofilament yarns in their weft, have the desirable properties that they tend to lay flat, do not bunch up, and track straight. However, such belts do not absorb or hold lubricants well.  
         [0017]     An interwoven fabric disclosed in U.S. Pat. No. 6,328,077 is two-ply fabric made of two layers of weft yarns in couplets, with warp yarns extending over and under adjacent couplets in a pattern where warp yarns extend under more couplets in the lower layer than extend over couplets in the upper layer. A central warp yarn of standard light denier extends between the upper and lower layers. This fabric works well as a solution to the aforementioned problems, but an improvement has been discovered that more effectively performs.  
       SUMMARY OF THE INVENTION  
       [0018]     According to the invention, a belting fabric comprises a plurality of adjacently disposed couplets of weft yarns, a plurality of binder warp yarns, and a plurality of middle warp yarns. The couplets form an upper layer of weft yarns and a lower layer of weft yarns. The binder warp yarns each extend over at least one of the couplets of weft yarns in the upper layer and under at least two of said adjacently disposed couplets of weft yarns in the lower layer. The middle warp yarns extend between the upper layer and the lower layers and are sufficiently straight and inelastic to bear loads under tension without twisting or stretching.  
         [0019]     Preferably, the middle warp yarns are formed of PET and have a denier of at least 550. Also, preferably, the middle warp yarns are heat set under tension.  
         [0020]     In another aspect of the invention a method of making a belting fabric includes the steps of arranging a plurality of couplets of weft yarns adjacent one another into an upper layer of weft yarns and a lower layer of weft yarns and weaving a plurality of middle warp yarns between the upper and lower layers. Also, a first warp yarn is woven over a first of said couplets of weft yarns and under a second and a third of the couplets of weft yarns, disposed adjacent the first of the couplets, a second warp yarn over a second of the couplets of weft yarns and under a third and fourth of the couplets of weft yarns, disposed adjacent the second of the couplets; and a third warp yarn over a third of the couplets of weft yarns and under fourth and fifth of the couplets of weft yarns, disposed adjacent the third of the couplets. Finally, the middle warp yarns are heat set. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is side elevational view of a section of conveyer belting material incorporating the principles of the invention;  
         [0022]      FIG. 2  is an enlarged side elevational view of the belting fabric of  FIG. 1 , having a weave pattern in accordance with principles of the invention;  
         [0023]      FIG. 3  illustrates the pattern of a single warp binder yarn in the weave pattern of  FIG. 2 ;  
         [0024]      FIG. 4  is an enlarged side elevational view of a section of conveyer belting fabric of  FIG. 1  having an alternate weave pattern in accordance with principles of the invention; and  
         [0025]      FIG. 5  illustrates the pattern of a single warp binder yarn in the weave pattern of  FIG. 4 . 
     
    
     DETAILED DESCRIPTION  
       [0026]     Shown in  FIG. 1  is a section of conveyor belting material  100  comprising a fabric layer  101  and a cover layer  102 . The cover layer  102  may be a standard rubber or plasticized polyvinyl material or the like. One embodiment of a belting fabric  100  in accordance with the invention is illustrated in  FIG. 2  in an enlarged side elevational view of a portion of the belt  100 . The belting fabric of  FIG. 2  includes an upper layer of monofilament weft yarns  105  and a lower layer of monofilament weft yarns  106 . The individual weft yarns of layer  105  are disposed in substantial alignment with individual weft yarns of layer  106 , forming a plurality of couplets,  110  through  119 . The monofilament weft yarns preferably have a diameter of approximately 0.3 mm.  
         [0027]     The two layers of weft yarns  105 ,  106  are separated by inelastic middle warp yarns  107  in accordance with the invention. The middle warp yarns are sufficiently straight and inelastic to bear loads under tension without twisting or stretching. Each middle warp yarn  107  is preferably formed of PET having a denier of 550, although any polymer, rendered effectively inelastic, will suffice. The middle warp yarns  107  are heat set under tension to make them straight and inelastic.  
         [0028]     A plurality of binder warp yarns  120 , 121 , 122  are woven on the weft yarns to form a belt fabric. The fabric layer  101  is woven in a repeating weaving pattern wherein three binder warp yarns  120 ,  121 , and  122  are woven through a plurality of adjacently disposed couplets formed from aligned pairs of weft yarns of layers  105  and  106 , in a specified pattern. In this pattern the first binder warp yarn  120  extends over a first aligned couplet of weft yarns  110  and under second and third couplets  111 ,  112 , respectively; the second binder warp yarn  121  extends over the second couplet  111  and under third and fourth couplets  112 , 113 , respectively; and the third binder warp yarn  122  extends over the third couplet  122  and under fourth and fifth couplets  113 , 114 , respectively.  
         [0029]     The specific pattern of the warp yarns shown in  FIG. 2  is further illustrated in  FIG. 3  in which the pattern of a single binder warp yarn  120  is shown separate from the other binder warp yarns.  
         [0030]      FIG. 4  depicts an alternate embodiment of a belt  200  in accordance with the invention wherein the fabric  201  comprises four binder warp yarns  220 ,  221 ,  222 , and  223  woven into two layers of weft yarns  206 , 207 . The layers of weft yarns  206 , 207  are separated by inelastic middle warp yarns  208  in accord with the invention. As before, each middle warp yarn  107  is preferably formed of PET having a denier of 550, although any polymer, rendered effectively inelastic, will suffice. The middle warp yarns  107  are heat set under tension to make them straight and inelastic.  
         [0031]     The binder warp yarns  220 ,  221 ,  222 ,  223  are preferably 1,000 denier yarns and the weft yarns  206 , 207  are preferably approximately 0.3 mm monofilament yarns. The fabric  201  is woven in a repeating weaving pattern wherein four binder warp yarns  220 ,  221 ,  222  and  223  are woven in a specified pattern through a plurality of couplets formed from pairs of aligned weft yarns of layers  206 ,  207 . In this pattern the first binder warp yarn  220  extends over a first aligned couplet of weft yarns  210  and under the second, third and fourth couplets  211 ,  212  and  213 , respectively; the second warp yarn  221  extends over the second couplet of weft yarns  211  and under the third, fourth and fifth couplets  212 ,  213  and  214 , respectively; the third warp yarn  222  extends over the third couplet of weft yarns  212  and under the fourth, fifth and sixth couplets  213 ,  214  and  215 , respectively; and the fourth warp yarn  223  extends over the fourth couplet of weft yarns  213  and under the fifth, sixth and seventh couplets  214 ,  215  and  216 , respectively.  
         [0032]     The specific pattern of the binder yarns of  FIG. 4  is further illustrated in  FIG. 5  in which the pattern of a single binder warp yarn, yarn  221 , is shown separate from the other binder warp yarns.  
         [0033]     Belt material in accordance with the present invention is preferably manufactured by feeding the woven belt fabric, e.g.,  100 ,  200 , from a roll of the fabric into a well-known belt coating apparatus. Such apparatus typically includes a feeding mechanism extending the belt between a roller and a coating knife. Liquid PVC, such as a well-known product referred to in the trade as “Plastisol,” is applied in a standard fashion. The belt material with the newly applied coating is then fed into an oven and heated by infrared lamps or the like to dissolve the applied PVC. After passing through the oven, the belt material with the applied PVC is fed between a roller and a cooling drum while cooling the belt. This causes the PVC to be forced into cavities in the woven material.  
         [0034]     One advantage of the belting fabric is that it has cavities of substantial size that provide for proper adhesion of the PVC layer to the fabric. As a result, glue lining required for belts made of prior art belt fabrics is not required. The application of such a glue lining requires that the belt material be fed through a glue application mechanism, similar to the PVC application mechanism. Accordingly, a belt made in accordance with the present invention is substantially less expensive to manufacture. More importantly, however, the stronger middle warp yarns are believed to be the ones primarily under tension during operation of the belt. Since they are the load-carrying yarns, the upper and lower layers on either side of the middle warp yarns are under no load, an thus do not wear as quickly as belts of the prior art. The result is a more durable belt.