CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present invention claims priority benefit of U.S. Provisional Patent Application No. 61/208,851 filed on February 27, 2009, which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention pertains generally to endless belts and particularly to seamless knit belts.

BACKGROUND OF THE INVENTION

[0003] Seamless belts are typically used where extreme flexibility or exact dimensions are required. Some common applications for seamless belts include paper and currency processing, packaging, business machines, fiber optics, general power transmission or the like. Unlike other endless belts, there is no splice or seam where the opposite ends are connected. The seamless belts are formed on tubular machines. For seamless knit belts, there is a well known issue with regard to curling along the edges because of the direction of the knitted loops. Accordingly, there is a need for a method of making seamless knit belts that addresses edge curling.

SUMMARY OF THE INVENTION

[0004] The present invention meets the above-described need by providing a seamless belt according to the independent claim 1 and a method of making a seamless knit belt according to the independent claim 8. Preferred embodiments will emerge from the dependent claims.

[0005] The essence of the invention consists in the following:

[0006] A seamless belt has a machine direction and a transverse direction. The seamless belt comprises a body section formed from a tubular knit material having a first stiffness and a pair of rib portions disposed on opposite sides of the body section. The rib portions are formed from a tubular knit material having a second stiffness that is greater than the first stiffness. The body section is treated.

[0007] A further aspect of the invention relates to a method, which method includes forming two longitudinal rib sections that are formed from a different material than the body of the knit composite. The rib sections are formed during the tubular knitting process and then the body of the knit composite is run through a polymeric treating system. After the body is treated, the rib sections are trimmed from the edges and the resulting product is a treated seamless knit belt.

[0008] Preferably, the rib portions of the seamless belt according to the invention are knitted from monofilament yarns .

[0009] Preferably, the rib portions of the seamless belt according to the invention are formed integrally with the body section during a single tubular knitting process. [0010] Preferably, the rib portions of the seamless belt according to the invention have a different knit pattern than the body section.

[0011] Preferably, the body section of the seamless belt according to the invention is treated with a polymer.

[0012] Preferably, the body section of the seamless belt according to the invention is treated with the polymer by coating.

[0013] Preferably, the pair of rib portions of the seamless belt according to the invention are knitted from different materials.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0014] The invention is illustrated in the drawings in which like reference characters designate the same or similar parts throughout the figures of which:

[0015] Fig. 1 is a perspective view of a prior art tubular knit composite;

[0016] Fig. 2 is a perspective view of an embodiment of a tubular knit composite according to the present invention; and,

[0017] Fig. 3 is a block diagram showing the steps of the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] Turning to Fig. 1, one type of seamless belt 10 is constructed with a tubular knit composite. The composite is produced on a tubular knitting machine as known to those of ordinary skill in the art based on this disclosure. The knit composite is first knit into a tubular shape with a pair of edges 13, 16 disposed in spaced apart parallel relation. Because of the well known tendency of knit tubing to curl at the edges (indicated by arrows 19) due to the direction of the knitted loops, there can be difficulties with further processing of the composite. For example, after the tubular composite is formed, the body of the composite may be treated with a rubber, silicone or similar material for some belt applications. During the treating process, the knit composite may be run in a machine direction indicated by arrow 22 and run through a treating system containing the polymeric material. The body of the composite may be treated in a rotational method such as knife coating as will be evident to those of ordinary skill in the art based on this disclosure.

[0019] Turning to Fig. 2, the seamless belt 10 of the present invention is divided into three sections in the transverse direction indicated by arrow 26. The first section 28 is a rib portion that is knitted from a different material such as a monofilament yarn to increase the stiffness of the composite and prevent edge curling in this area. The second or body section 31 is constructed of a different material than the first section 28, and in some cases the second section 31 comprises a different knit pattern. The body section 31 is constructed according to the specifications for the final seamless knit belt product. The third section 34 is also knitted from a monofilament or other material that is selected for greater stiffness and resistance to edge curling. After the composite knit substrate is formed as described, the body of the composite is treated with a polymeric material as described above. The web may be conveyed through the treating system in the machine direction indicated by arrow 25 by rotating it around drums or sprockets that support the web at opposite ends. After the treating step is completed and the polymer has cured, the first section 28 and the third section 34 are trimmed away by an edge trimming device as will be evident to those of ordinary skill in the art based on this disclosure. After the first and third sections 28 and 34 are trimmed away from the body section 31, the resulting product is a treated seamless knit belt.

[0020] Turning to Fig. 3, a block diagram shows the steps of the method of the present invention. In step 37, the composite tubular knit is formed with a body section surrounded by two rib sections extending from the body section in the transverse direction. In the next step 40, the body of the composite is treated with a polymeric coating substance. Next, the body is cured in step 43. After the curing step, the edges are trimmed in the final step 46.

[0021] While the invention has been described in connection with certain embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the scope of the invention as defined by the appended claims.