Rubber-Steel Conveyor Belt

This study deals with a specially designed conveyor belt for installation in the new coal mine at Selby, Yorkshire. The belt has been designed, and is now being manufactured, by BTR Belting Ltd. Leyland, Lancashire. 

A conveyor belt is a long narrow slab of material, designed to hold material with sufficient longitudinal strength to withstand the pull of its drive under load. 

Traditionally belting is made with woven textile reinforcement - cotton, later nylon and PET. 

For some types of load there is a requirement for high transverse strength to withstand damage from abuse - sharp, abrasive loads, e.g. steel scrap. Insufficient transverse strength in such cases leads to slits running longitudinally. Transverse reinforcement is also necessary when mechanical fasteners are to be used. 

The traditional approach to long hauls was a multiple-conveyor system, with transfer points. Objections to this are the need for manning and the risk of abrasion and blockages at transfer points. 

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CHAPTER TWENTY-ONE Rubber-Steel Conveyor Belt BTR Ltd... 

Since belted radial tires were introduced in 1948 by Michelin, steel as well as polyester and aramid have been used to make the tire cord for the radial belt. Steel has historically also been used to make the bead wire in tire construction. In addition, steel has been used to manufacture the cable that is used in making rubber mining conveyor belts. Lastly, in the automotive industry, many times rubber parts are made that are composites of rubber and steel. Examples of these parts are seen with motor mounts and bushings. 

Continuous vulcanisation of rubber based products such as thin conveyor belting, flooring and similar can be achieved using a large rotating heated drum. Pressure is exerted to the product by means of a continuous stainless steel belt which presses the sheet to the surface of the drum. The belt is also heated from its reverse side to give optimum heat transfer to the vulcanising rubber. 

Alternatively, the doctor blade can impinge onto a small conveyor belt system which supports the travelling fabric. This mechanism is less commonly used than the rigid roller as it leads to reduced control of the thickness of the spread. For precision work, using very consistent cloth, an accurately machined chromium plated steel roll can replace the rubber covered roller. 

Rubber consumption is dominated by tyre production. In these, conveyor belts, and pressure hoses, thin layers of either steel wire or polymeric fibre reinforcement take the main mechanical loads. These layers, with rubber interlayers, allow flexibility in bending, whereas the reinforcement limits the in-plane stretching of the product. The applications are dominated by natural rubber and styrene butadiene copolymer rubber (SBR). Other rubbers have specialised properties butyl rubbers have low air permeability, nitrile rubbers have good oil resistance, while silicone rubbers have high and low temperature resistance. Rubbers play a relatively small role in this book, but the rubbery behaviour of the amorphous phase in semi-crystalline thermoplastics is important. 

Tires are one of the most durable technological products manufactured today. They are a resilient, durable composite of fabric, steel, carbon black, natural rubber, and synthetic polymers. The qualities that make tires or other engineered rubber products a high-value item create a special challenge of disposal. Tires and other rubber products, such as conveyor belts and hydrauUc hoses, are not biodegradable and cannot be recycled like glass, aluminum, or plastic. Four potential applications for such products entering the solid waste stream have been identified ... 

Mechanical rubber goods include hoses, power transmission (PT) belts, and conveyor belts. Aramids compete with nylon, polyester, glass, and steel in these applications. Steel dominates the rubber hydraulic hose market and polyester is the reinforcement of choice in lower pressure thermoplastic hoses. Advantages of aramid vs. other textiles in hose applications include higher strength, which can lead to constructions with fewer plies and less weight, and better thermal stability, dimensional stability, and chemical resistance. When compared with steel, aramid will not corrode and can be fabricated into lower weight, more flexible hoses. 

Conveyor belts incorporate planar, equi-spaced, rubber embedded steel cords. Tensile loads are carried by the steel cords. Belts are spliced by interleaving the cords within the rubber embedment. Tensile cord loads are transferred at the splice by rubber in shear. 

Steel cord conveyor belts are a composite of steel wire cord and rubber. Synthetic fiber cord conveyor belts are a composite of synthetic fiber cord and rubber. Tensile loads are carried by the steel wire or synthetic fiber cord. Tensile loads are transferred through the splice by the rubber in shear. 

Steel cord for the Selby belt is purchased from Bekaert (Belgium). As already described, the steel cord used in conveyor belting is derived from that used in tyres. It is purchased from specialist suppliers, such as Bekaert and Steel Cords Ltd. Ordinary suppliers of steel cable for other purposes do not usually supply the rubber industry. There are two reasons for this one is the fluctuation and lack of standardization of demand, and the other is the chemically clean, zinc-coated finish required. 

Conveyor belt, rubber-steel cord, 226-51 adhesion test, 228, 245 belt building, 242 cable spacing, 248 Cadley Hill, 233, 235... 

Steel cord has been the main reinforcing material for tyres, hoses and conveyor belts for many decades, indeed the first steel reinforced tyres appeared over ninety years ago. However, it was not until the emergence of radial tyres that steel cord became a common form of reinforcement and understandably the adhesion between brass-coated steel cord and rubber compound became a significant factor governing the performance and durability of car and truck tyres. Therefore, it is necessary to achieve a high level of adhesion and sustain this level throughout the service history of the tyre. 

Iron is used to produce steel tire cord for tires and cable for rubber conveyor belts. It is also used to make rubber metal composites for dynamic applications for automobiles and machinery. 

Several plants employ cooled-belt flakers. These consist of flexible steel belts, ca 1-m wide and up to 50-m long, that have short rubber skirting at the edges. Molten pitch flows from a thermostatically controlled tank over a weir to give a flat thin sheet on the belt, which is cooled from below by water sprays. At the end of the belt, the solid pitch is broken up by rotating tines. The pitch flakes are drained and transported to a covered storage silo by belt conveyor, during which time the surface moisture evaporates. 

Related Calculations. This procedure is valid for conveyors using rubber belts reinforced with cotton duck, open-mesh fabric, cords, or steel wires. It is also valid for stitched-canvas belts, balata belts, and flat-steel belts. The required horsepower input includes any power absorbed by idler pulleys. 

This type of "belt" conveyor is equipped with a cold-rolled hardened steel band in lieu of a "rubber" belt and is used for special purposes. The thickness of the band is usually in the range of 1.0 to 1.5 mm. Because of the flat and smooth surface of the band, the material can very suitably be discharged by means of ploughs (or scrapers). Such conveyors are not very suitable for the handling of hot materials unless the band acquires a uniform temperature across its whole width otherwise buckling is liable to occur in consequence of differential thermal expansion, causing serious trouble in the operation of the conveyor. 

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