Abstract:
A belt and method of marking a belt. A layer of polyethylene material is joined or cured to a belt. The layer is optically distinguishable from a belt body. The layer is etched to expose a portion of the belt body in order to contrast the layer with the belt body. A second layer of polyethylene material may be applied adjacent to the first layer. The second layer is optically distinguishable from the first layer. The first or second layer is etched using cutting, grinding or laser light in order to expose portions of the adjacent layer, or of the belt body, thus providing a method of permanently marking the belt.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. provisional application No. 60/393,800 filed Jul. 3, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to a belt and method of marking a belt and more particularly, to a belt and method of marking a belt using at least one optically distinguishable polyethylene layer.  
         BACKGROUND OF THE INVENTION  
         [0003]    Belts may be manufactured with or without marking indicia. Marking indicia may comprise labels, text or other material impressed or printed directly on the belt or a combination of the foregoing.  
           [0004]    More particularly, the prior art teaches use of a non-vulcanized colored rubber which is adhered to a base material. During vulcanization the colored rubber is imprinted upon the underlying material. This often results in distorted markings or undesirable surface features, such as dips of bumps. Such dips or bumps can cause noise during operation of the belt. It is also known that a laser may be used to apply a mark to a belt by burning or etching a mark in a product surface.  
           [0005]    Representative of the art is Japanese Patent No. 3126937 which discloses a method for marking a belt.  
           [0006]    What is needed is a belt and a method of marking a belt using a polyethylene layer that is optically distinguishable from a belt body. What is needed is a belt and a method of marking a belt using an optically distinguishable polyethylene layer etched by a laser light. The present invention meets these needs.  
         SUMMARY OF THE INVENTION  
         [0007]    The primary aspect of the present invention is to provide a belt and a method of marking a belt using a polyethylene layer that is optically distinguishable from a belt body.  
           [0008]    Another aspect of the invention is to provide a belt and a method of marking a belt using an optically distinguishable polyethylene layer etched by laser light.  
           [0009]    Other aspects of the invention will be pointed out or made apparent by the following description of the invention and the accompanying drawings.  
           [0010]    The invention comprises a belt and method of marking a belt. A layer of polyethylene material is joined or cured to a belt. The layer is optically distinguishable from a belt body. The layer is etched to expose a portion of the belt body in order to contrast the layer with the belt body. A second layer of polyethylene material may be applied adjacent to the first layer. The second layer is optically distinguishable from the first layer. The first or second layer is etched using cutting, grinding or laser light in order to expose portions of the adjacent layer, or of the belt body, thus providing a method of permanently marking the belt. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a cross sectional perspective view of a belt having an optically distinguishable polyethylene layer.  
         [0012]    [0012]FIG. 2 is a perspective view of a belt having an optically distinguishable layer etched by laser light.  
         [0013]    [0013]FIG. 3 is a cross-sectional view of a multi-ribbed profile. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    [0014]FIG. 1 is a cross sectional perspective view of a belt having an optically distinguishable polyethylene (PE) layer. The illustrative product comprises a power transmission belt  100  used, for example, in an automotive or industrial application.  
         [0015]    Belt  100  comprises an elastomeric body  10  with tensile members  20  embedded therein. The tensile members  20  extend parallel to a longitudinal axis. Tensile members  20  may comprise any material known in the belt art, including polyester, nylon, aramid and their equivalents. Tensile members  20  extend longitudinally within the body  10 .  
         [0016]    A profile comprising transverse teeth or cogs  11  extend transverse to and along a longitudinal surface of the belt body  10 . The profile may also comprise a multi-ribbed surface, see FIG. 3.  
         [0017]    Layer  30  comprises a thermoplastic material. Thermoplastic layer  30  is joined to body  10  by use of any suitable cure, chemical adhesive or molding process known in the art. Although the preferred embodiment uses a peroxide cure process, thermoplastic layer  30  may also be joined to body  10  using chemical adhesives known in the art and by molding.  
         [0018]    Body  10  may comprise thermoset elastomeric material such as hydrogenated nitrile butadiene rubber (HNBR), ethylene-propylene (diene) rubber (EPDM), styrene-butadiene rubber (SBR), chloroprene rubber (CR), natural rubber (NR), nitrile rubber (NBR), butyl rubber (BR) or any other elastomeric materials used in power transmission belts.  
         [0019]    Layer  30  is selected with beneficial characteristics to create an optical appearance or contrast that is distinguishable from a belt body  10  or adjacent layer. Optical as used herein refers to visual and non-visual electromagnetic (EM) radiation. Layer  30  has a thickness in the range of approximately 3.5 mils to 30 mils.  
         [0020]    The characteristics of the layer may include a particular color, texture, or reflectivity that optically distinguishes layer  30  from belt body  10 . The difference in appearance, or contrast, results from differences in reflected electromagnetic (EM) radiation so that the layer  30  can be distinguished from belt body  10  by a person&#39;s eye (visually), with an optical scanner such as a bar code reader, or by any other scanner or means of detecting visual or non-visual EM radiation. Layer  30  may also comprise any visually detectable color or combination of colors. In the instant embodiment layer  30  comprises polyethylene (PE) having a particular distinguishing characteristic, that is, color, preferable other that black. By way of example and not of limitation, layer  30  may also substantially comprise polypropylene, polyester, polyamide, polyvinylidene chloride, polyvinyl chloride and any equivalents or combinations thereof. Each of the foregoing being optically distinguishable. In the case of polyethylene, layer  30  is compatible with and co-curable with ethylene propylene rubbers via peroxide cure.  
         [0021]    Use of polyethylene has the advantage of avoiding the need for a separate rubber mixing step as is the case with prior art colored rubber stocks. The PE sheet material has additional advantages including availability in a wide range of thicknesses, relatively low cost compared to mixing rubber stocks, ease of storage and processing, and it is readily recyclable.  
         [0022]    [0022]FIG. 2 is a perspective view of a belt having an optically distinguishable layer etched by laser light. In this embodiment layer  40  is molded, joined or cured to the belt body  10  under layer  30 . Layer  40  has a thickness in the range of approximately 3.5 mils to 30 mils.  
         [0023]    Once the belt is cured or molded, a laser light  60  from a laser light source  61  is focused upon a selected portion of layer  30 . The intensity and position of the laser light source  61 , and thereby the laser light  60 , is adjusted and moved in order to remove selected portions of layer  30  without damaging underlying layer  40 , thereby exposing a portion of layer  40 . The intensity of the laser light  60  may be adjusted in order to penetrate any thickness of layer  30 . Since layer  30  is optically distinguishable from layer  40 , the removed portions of layer  30  expose layer  40 , which then comprise a detectable mark on the belt. As an example, mark  50  depicts the number “20”. Of course, any symbol, text, or other desired pattern can be etched into layer  30  to serve as a mark on the belt or product.  
         [0024]    Layer  30  may also be etched to mark a belt in the absence of layer  40 . In this embodiment, belt body  10  provides a particular optical appearance and contrast to distinguish it compared to layer  30 . The optical appearance of layer  30  is properly selected to distinguish it from the optical appearance of belt body  10 .  
         [0025]    In another embodiment, prior to cure layer  30  has selected portions removed, for example by etching, cutting or grinding prior to assembling and curing the belt. Cuts in layer  30  depict the same mark as described in FIG. 2, only the cuts used to make mark  50  are not performed using laser light. They may be ground or die cut into layer  30  using tools known in the art. The layer would then be cured or molded with the product as otherwise described herein, rendering a permanent marking of the belt or product.  
         [0026]    In yet another embodiment a plurality of optically distinguishable layers are ‘stacked’ or layered together on a belt. Each layer has an appearance which contrasts with or distinguishes it from each of the other layers. A laser light is then selectively operated at different intensities and positions in order to remove selective portions of overlying layers to expose different portions of particular underlying layers. In this manner a variable appearance is etched into the belt or other product. This may include different colors and layers being exposed to indicate different information about the belt, for example, part or inventory numbers. It may also be used to create a visually appealing effect on a belt or product using different colors and patterns. Although FIG. 2 depicts two layers as an example and not as a limitation, any number of layers may be stacked to achieve the described effect.  
         [0027]    In yet another embodiment a plurality of optically distinguishable layers are ‘stacked’ or layered together on a product as described previously. Each layer has a different appearance to distinguish it from each of the other layers. In this embodiment a knife, grinder, cutting tool, or die cutter is used to remove portions of overlying or underlying layers to selectively expose different portions of particular layers. In this manner a variable appearance may be realized on the belt or product. As described herein, this may include different colors and layers being exposed to illustrate different information about the belt or product. It may also be used to create a visually appealing effect on a belt or product using different colors. Although FIG. 2 depicts two layers as an example, any number of layers may be stacked to achieve the described effect.  
         [0028]    In yet another embodiment, separate regions having different colors may be formed in each layer  30  and layer  40 . The different color regions in each layer may be disposed laterally adjacent to each other across a surface of layer  30  or layer  40 . They may also have any form as may be required to achieve a desired visual effect.  
         [0029]    For example, referring to FIG. 3, regions  31 ,  42  may be blue, while regions  32 ,  41  may be green and so on, each region being adjacent to each other and disposed parallel to a belt length. Each region being optically distinguishable from all other adjacent regions both vertically and laterally. Each region is then etched in order to expose differing portions of each adjacent region. This affords yet another means of making unique markings on a belt or product.  
         [0030]    [0030]FIG. 3 is a cross-sectional view of a multi-ribbed profile. A profile comprising ribs  110  extend along a longitudinal axis of a belt. Regions  31 ,  32 ,  41 ,  42  of layer  30  and layer  40  each have having differing optical appearances are depicted.  
         [0031]    Although forms of the invention have been described herein, it will be obvious to those skilled in the art that other variations may be made in the construction and relation of parts without departing from the spirit and scope of the invention described herein.