Patent Application
20180229415
The present invention relates to monolithic belting having coated reinforcing cords.
Reinforced monolithic belts have been manufactured in one of two ways. In the first method, the belt material (generally a thermoplastic resin) is extruded onto a molding wheel 90 having “flights” 92 or “noses” (see
The other method used to manufacture such belts was designed to make flightless belts. In this method, the extruded resin is applied in two layers. A first layer of resin is applied to a molding wheel and a reinforcing cord is laid onto the first layer. Then, a second layer of resin is deposited onto the first, thereby embedding the cord between the layers. While this method is successfully used to create a flightless belt, belts made in this fashion have been found to suffer from premature failure, such as delamination failures, where the layers of the belt separate.
There is a need for a manufacturing method to create a belt which resists contamination, is easy to clean, and is structurally sound. Such a method of manufacture should also allow precise placement of the reinforcing cord, and create belts wherein the cord is not susceptible to corrosion through exposure.
The present invention meets the above-described need by providing a method for making a reinforced monolithic belt according to independent claim 1 and a system (apparatus) for making a reinforced monolithic belt according to independent claim 7. Preferred embodiments will emerge from the dependent claims.
The present invention provides a system and method of making no flight timing belt or flat belt in a single pass using elastomer, such as thermoplastic urethane or, generally, thermoplastic elastomer, and coated reinforcing cord. The present techniques reduce manufacturing times and costs. Producing belts with no flights allow reduced potential for contamination and corrosion. The present techniques also provide one-step manufacturing process for accurate positioning of reinforcing cord to provide proper pitch line differential (PLD) for a belt with good pulley engagement.
For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which:
The present invention provides a system and method for manufacturing open ended belts made of an elastomeric matrix in which one or more tension members (reinforcing cords) are embedded into the belt material in a longitudinal direction. Such belts can be toothed belts, flat belts, multi-V-ribbed belts, conveyor belts, or similar belt products. The invention is particularly useful for making toothed belts which require precise control of tooth spacing or pitch, as well as accurate cord positioning, resulting in precise PLD.
With reference to
The system 10 comprises a molding wheel 12, which is configured to rotate. In some embodiments, the molding wheel 12 has a series of ridges 14 for forming corresponding structures (e.g., teeth) in the resulting belt 85 (see, e.g.,
A die head 42 is configured to deposit and spread extruded belt material 80 onto the molding wheel 12. The belt material 80 is the material that makes up the bulk of the belt 85. The material may be an elastomer, for example, thermoplastic urethane (TPU), thermoplastic elastomer (TPE), or other thermoplastics or blends thereof. The invention can also be adapted for use with castable or thermoset resins or for a vulcanized rubber matrix. For example, a coated cord can be passed into the mold and a thermoset material can be deposited to form a timing belt from a thermoset resin. The die head 42 is located such that the extruded belt material 80 is deposited ahead of the entrance 32 such that, as the molding wheel 12 rotates, the extruded material 80 is moved through the entrance 32 into the mold cavity 30. As will be apparent to one having skill in the art in light of the disclosure, the material is deposited onto the molding wheel 12 at an elevated temperature and cools while in the mold cavity 30 such that the material will hold its form when exiting the mold cavity 30.
The system 10 comprises a feeder 44 which is configured to pass a coated reinforcing cord 45 onto the molding wheel 12 ahead of the entrance 32 to the mold cavity 30. The reinforcing cord 45 may be coated with a thermoplastic or other material compatible with the belt material 80. By compatible, it is intended that the coating of the coated cord 45 will bond with the belt material 80 so as to maintain integrity of the bond after the belt 85 is formed. In some embodiments, the coating of the cord is the same material as the belt material 80. For example, in an exemplary embodiment where the belt material is TPE, the reinforcing cord may be coated with TPE.
The tension members (reinforcing cords 45) typically comprise coated cords, yarns, fibers, or filaments of steel, but could alternatively or additionally comprise stainless steel, glass, aramid, carbon, polyester, polyamide, basalt, or other suitable materials or hybrids thereof. A yarn may be a bundle of fibers, filaments, or wires and may be twisted or cabled. A cord may be a twisted, braided, or cabled yarn or bundle of yarns. The terms wire and cable are often used in connection with metal cords or metal tension members. The terms “cord” and “tensile member” are used herein to refer to all types of tension members. Fabric layers or other non-typical types of tensile reinforcement may also be used as the tensile members of the invention.
By using a coated reinforcing cord 45, the cord 46 is held off of the molding wheel 12 by the coating, without the use of flights. As such, the distance, Hcord, between the bottom (land region) 86 of the belt 85 is substantially the same as the thickness, Tcoating, of the coating 47 of the coated reinforcing cord 45 (see, e.g.,
In another aspect of the present invention, a method 100 for making a reinforced monolithic belt is provided. The method 100 comprises depositing 103 extruded belt material onto a rotating molding wheel. In some embodiments, the material is passed 112 under a spreader to further spread the material onto the molding wheel. The material is passed 106 into a mold cavity formed by an endless band cooperating with a peripheral portion of the molding wheel. A coated reinforcing cord is laid 109 onto the molding wheel ahead of the mold cavity. In some embodiments, the reinforcing cord is laid 109 onto the molding wheel ahead of where the belt material is deposited 103 onto the molding wheel. As such, the belt material is deposited 103 onto the reinforcing cords. In other embodiments, the reinforcing cord is laid 109 onto the molding wheel behind where the belt material is deposited 103 molding wheel such that the cord is laid into the extruded material.
The belt material, the cord coating material, and the cord may be of any type, such as those described above.
Through the use of the presently disclosed techniques, a belt is produced where cord fraying can be reduced by elimination of a flight area, thereby providing a longer belt lifespan, reduced potential for contamination, and reduced potential for corrosion, for example, in the case of steel cord.
Although the present invention has been described with respect to one or more particular embodiments, it will be understood that other embodiments of the present invention may be made without departing from the spirit and scope of the present invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/067900 | 7/27/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62199214 | Jul 2015 | US |
