Mobius belt and method of making the same
BACKGROUND OF THE INVENTION 
     This invention relates to endless power transmission belts, and in particular, to endless power transmission belts of spliceless Mobius strip construction. 
     A &#34;Mobius strip&#34;, named after the German astronomer and geometer August Ferdinand Mobius (1790-1868), has fascinated mathematicians and others for years. The Mobius strip is generally defined as a surface with only one side and one edge, made by placing a twist of 180 degrees in a long rectangular strip and then securing the ends of the strip together. 
     The Mobius strip principle has been utilized or proposed for various applications including the formation of endless belts and the like, as shown for example in U.S. Pat. Nos. 1,442,682, 2,479,929, 2,784,834 and 3,302,795. However, these previously proposed Mobius strip belts were of the type that were spliced to make the belt endless and, therefore, retained the undesirable characteristic of having a splice or point of joinder in the endless belt which is subject to surface and edge wear. U.S. Pat. No. 3,991,631 has proposed a Mobius belt of woven construction. However, woven construction is generally considered to be too expensive to be practical. 
     Accordingly, it is an object of this invention to provide an improved endless power transmission belt having an increased surface and edge wear potential, and which eliminates the splice therein and overcomes wear at the splice of the belt. Other objects, aspects and advantages of the present invention will be apparent to those skilled in the art from the following description when taken in conjunction with the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided an endless belt of spliceless, Mobius strip construction comprising a continuous strength cord wrapped generally in the form of a helix of predetermined length and width and having a 180 degree turn at a given location along the length thereof, and a layer of an elastomeric material embedding the cord. 
     Also provided in accordance with the present invention is a process for making a spliceless, Mobius belt. 
     In accordance with one embodiment of the present invention, an endless belt of spliceless, Mobius strip construction is made by wrapping an elongate strip of elastomeric material around two spaced apart building supports, turning one end of the strip through 180 degrees and joining the two ends of the strip, thereby forming a Mobius strip, winding a continuous strength cord in the form of a helix around the Mobius strip and across the entire width thereof, winding at least one layer of elastomeric material over the cord winding to provide an assembly, and vulcanizing or otherwise curing the elastomeric material. 
     In accordance with another embodiment of the present invention an endless belt of spliceless, Mobius strip construction is made by wrapping an elongate strip of an elastomeric material around two spaced apart building supports, turning one end of the strip through 180 degrees and joining the two ends of the strip, thereby forming a Mobius strip, winding a continuous strength cord in the form of a helix around the Mobius strip and across one-half the width thereof, squeezing the cord into approximately a single plane, winding at least one layer of an elastomeric material around the cord winding to provide an assembly and vulcanizing or otherwise curing the assembly. 
     In accordance with yet another embodiment of the present invention, there is provided a process for making an endless belt of spliceless, Mobius strip construction which comprises the steps of wrapping an elongate strip of an elastomeric material around two spaced apart building supports, turning one end of the strip through 180 degrees and joining the two ends of the strip, thereby forming a Mobius strip, winding a continuous strength cord in the form of a helix around the Mobius strip and across one-half the width thereof, winding at least one layer of an elastomeric material around the cord winding to provide an assembly, passing the assembly between means for squeezing the cord into approximately a single plane, and vulcanizing or otherwise curing the assembly. 
     In accordance with a further embodiment of the present invention, there is provided a process for making an endless belt of spliceless, Mobius strip construction which comprises the steps of wrapping an elongate strip of a calendered cord fabric having a length equal to at least two times the length of the finished belt around two spaced apart building supports, turning one end of the strip through 180 degrees and joining the turned end to a portion of the strip and continuing to wrap the remainder of the strip around the building supports, winding at least one layer of an elastomeric material around the fabric to provide an assembly, and vulcanizing or otherwise curing the assembly. 
     In accordance with a yet further embodiment of the present invention, there is provided a process for making an endless belt of spliceless, Mobius strip construction which comprises the steps of providing a warp consisting essentially of at least one continuous warp cord wrapped generally in the form of a helix of predetermined length and width and having a 180 degree turn at a given location along the length thereof, winding at least one layer of an elastomeric material around the cord winding to provide an assembly and vulcanizing or otherwise curing the assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 illustrates an endless belt of spliceless, Mobius strip construction; 
     FIGS. 2-6 illustrate one embodiment of the process of this invention; 
     FIGS. 7-11 illustrate another embodiment of the process of this invention; 
     FIGS. 12-14 illustrate yet another embodiment of the process of this invention; 
     FIG. 15 illustrates a further embodiment of the process of this invention; 
     FIG. 16 illustrates yet a further embodiment of the process of the present invention; 
     FIG. 17 illustrates another embodiment of the belt of this invention; 
     FIGS. 18-21 illustrate further embodiments of the belt of this invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings, FIG. 1 illustrates an endless belt, generally indicated at 30, suitable for being rotated in either direction during use. The belt 30 would normally be suspended over and around at least two pulleys 32 and 34. 
     The belt 30 is of a spliceless, Mobius strip construction having a 180 degree turn 36 for providing, in effect, one spliceless continuous edge of twice the predetermined length of the belt during rotation thereof. The belt 30, as will hereinafter become apparent, comprises a continuous strength member embedded in an elastomeric material. 
     Referring now to FIGS. 2-6, and in accordance with one embodiment of the invention, the belt 30 may be made by first wrapping an elongate strip 38 of an elastomeric material around two spaced apart building drums 40 and 42, turning one end of the strip 38 through a 180 degree turn, as at 44, and butt splicing the two ends of the strip 38, as shown at 46, thus forming a Mobius strip. A strength cord 48 is wound in the form of a helix around the Mobius strip. As the cord is wound across the width of the Mobius strip it will appear, in cross-section, to be on opposite sides of the strip 38. For example, and as shown in FIG. 3, when the cord 48 is wound across one-half the width of the strip 38, the cord 48 appears, in cross-section, to be disposed along the top left side and along the bottom right side of the strip 38. It should be kept in mind that the Mobius strip has but a single side or surface and that the cord cross-sections are all disposed on that one surface. It should also be noted that the relative sizes of the elastomeric strip 38 and the cord 48, and the spacing of the cord 48 are exaggerated for the purpose of illustration. 
     The winding of the cord 48 is continued across the entire width of the strip 38, as shown in FIG. 4. A second elongate strip 49 of elastomeric material is then wound around the cord winding to provide the assembly shown in FIG. 5. This assembly is then vulcanized, or otherwise cured, by placing the same in a vulcanizing press between press platens 50 and 51, to provide a completed belt 52. During the vulcanizing step the first strip 38 and the second strip 49 coalesce, i.e., flow together, to provide an elastomeric body, now designated 53, completely surrounding and embedding the cord 48. 
     Referring now to FIGS. 2, 3 and 7-11, and in accordance with another embodiment of this invention, an elastomeric strip 38 is wound around building drums 40 and 42, one end is turned 180 degrees, as at 44, and the ends are butt spliced, as at 46. The cord 48 is wound around the Mobius strip and across about one-half the sub-assembly 54 shown in FIG. 3. The cord windings lie in planes 55 and 56. These cord windings are pressed into a single plane 57, by passing this sub-assembly 54 between offset roller pairs 58 and 59, as shown in FIG. 7. A narrow strip 60 of elastomeric material is wound over the cord windings, as shown in FIGS. 8-10, to provide an assembly 62. The assembly 62 is then vulcanized or otherwise cured, by placing the same in a vulcanizing apparatus between platens 64 and 66, to provide a completed belt 68. During the vulcanizing step, the first strip 38 and the narrow strip 62, flow together to provide an elastomeric body, designated 70, completely surrounding and embedding the cord 48, as shown in FIG. 11. 
     Another embodiment of the invention is shown in FIGS. 2, 3 and 12-14. In accordance with this embodiment, an elongate, elastomeric strip 72, having a width approximately equal to the width of the strip 38, is wound around the cord 48 of the sub-assembly 54. The resulting assembly is vulcanized, or otherwise cured, by pressing the same in a vulcanizing press between press platens 74 and 76 to provide a completed belt 78. During the vulcanizing step, the elastomeric strips 38 and 68 flow together to provide an elastomeric body, designated 80, completely surrounding and embedding the cord 48. Also during the vulcanizing step, the cord planes 55 and 56 are shifted closer together to planes 55&#39; and 56&#39;, as shown in FIG. 14, and may or may not be shifted to a single cord plane, depending upon the plasticity of the elastomeric compound. 
     Referring now to FIG. 15, a further embodiment of the invention is made by wrapping an elongate strip of cord fabric having a length at least equal to two times the length of the finished belt around two building drums, turning one end of the strip through 180 degrees, joining the turned end to a portion of the remaining strip, continuing to wrap the remainder of the strip around the thus-formed loop, winding at least one layer of an elastomeric material around the cord fabric to provide an assembly, and vulcanizing, or otherwise curing, the assembly to provide a finished belt 82. The cord fabric comprises a plurality of generally parallel strength members 84, held in parallel relation by a plurality of interwoven, relatively weak tie members 86. The cord fabric is disposed so that the strength members 84 are parallel to the longitudinal axis of the belt 82. A layer of elastomer 88 is wound around the layers of cord fabric and the resulting assembly is then vulcanized, or cured. It is generally preferred that the cord fabric used to make the belt 82 have a thin layer of elastomeric material calendered thereto. 
     A yet further embodiment of the invention is shown in FIG. 16. A belt having the appearance of the belt 68, shown in FIG. 11, can be made by winding a continuous warp cord 90, generally in the form of a helix of predetermined length and width, and having a 180 degree turn at a given location along its length, around two building supports or drums, winding at least one layer of elastomeric material 92 around the cord winding, and vulcanizing the resulting assembly. 
     Other embodiments of the belt of this invention are shown in FIGS. 17-21. The belt 94, shown in FIG. 17 comprises a continuous cord 96 strength member embedded in and surrounded by an elastomer 98 and having an outside fabric cover 100 which defines the continuous surface of the belt 94. The fabric cover 100 is applied over the outer most elastomeric layer prior to the vulcanizing step in order to bond the fabric to the elastomeric material. The belts 52, 78 and 82 shown in FIGS. 6, 14 and 15, respectively, may also have a fabric cover. 
     Endless belts having cross-sections other than a flat cross-section may also be made in accordance with the invention. The belt 102, shown in FIG. 18, has a cross-section known in the art as a &#34;double-V&#34;. The belt 102 may be made by grinding the inverted &#34;V&#34; profile using a profiled grinding wheel 104. 
     The belt 106, shown in FIG. 19, is known in the art as a multi-rib belt and, in the embodiment shown, has two truncated ribs 108. The belt 106 is shown being molded and vulcanized in a mold 110, only one-half of the mold being illustrated for clarity of illustration. 
     The belt 112, shown in FIG. 20, is known in the art as a &#34;double V-ribbed&#34; belt and comprises a plurality of V-shaped ribs defined by a plurality of alternating projections 114 and recesses 116. The belt 112 may be made by grinding, or molding, or a combination of molding and grinding. 
     The belt 118, shown in FIG. 21, is a &#34;toothed double-V&#34; belt having a plurality of teeth defined by alternating transverse projections 120 and recesses 122 along the endless path of the belt. 
     The cords 48 and 90 employed in the various embodiments of this invention can be made of any material, natural or synthetic, known in the art, such as, for example, cotton, rayon, nylon, polyester, aramid, and the like. 
     The terms &#34;elastomer&#34; and &#34;elastomeric material&#34;, as used herein and in the claims, are intended to include both natural and synthetic, thermosetting and thermoplastic materials having elastomeric properties. The thermosetting materials must be vulcanized, or otherwise cured, in order to have useful elastomeric properties. The most common thermosetting elastomeric material is rubber, either natural or synthetic, and the preferred rubber is neoprene. Suitable thermoplastic elastomers include the polyurethanes and EPDM. 
     The fabric 100 used in making the belt 94 can be any fabric known in the art. 
     Reasonable modifications are possible within the spirit of the disclosure without departing from the scope of the following claims.