conveyor belt

This article is about industrial conveyor belts. For information on the global flow of sea currents, see Thermohaline circulation.

Point of contact between a power transmission belt and its pulley. A conveyor belt uses a wide belt and pulleys and is supported by rollers or a flat pan along its path.

These conveyor structures contain belts for moving bulk sulfur from railcars to storage piles and from the piles to ships.

A belt conveyor consists of two pulleys, with a continuous loop of material - the conveyor belt - that rotates about them. One or both of the pulleys are powered, moving the belt and the material on the belt forward. The powered pulley is called the drive pulley while the unpowered pulley is called the idler. There are two main industrial classes of belt conveyors; Those in general material handling such as those moving boxes along inside a factory and bulk material handling such as those used to transport industrial and agricultural materials, such as grain, coal, ores, etc. generally in outdoor locations. Generally companies providing general material handling type belt conveyors do not provide the conveyors for bulk material handling. In addition there are a number of commercial applications of belt conveyors such as those in grocery stores.

The belt consists of one or more layers of material. Many belts in general material handling have two layers. An under layer of material to provide linear strength and shape called a carcass and an over layer called the cover. The carcass is often a cotton or plastic web or mesh. The cover is often various rubber or plastic compounds specified by use of the belt. Covers can be made from more exotic materials for unusual applications such as silicone for heat or gum rubber when traction is essential.

Conveyor belt to power a threshing machine by a steam tractor

Material flowing over the belt may be weighed in transit using a beltweigher. Belts with regularly spaced partitions, known as elevator belts, are used for transporting loose materials up steep inclines. Belt Conveyors are used in self-unloading bulk freighters and in live bottom trucks. Conveyor technology is also used in conveyor transport such as moving sidewalks or escalators, as well as on many manufacturing assembly lines. Stores often have conveyor belts at the check-out counter to move shopping items. Ski areas also use conveyor belts to transport skiers up the hill. A wide variety of related conveying machines are available, different as regards principle of operation, means and direction of conveyance, including screw conveyors, vibrating conveyors, pneumatic conveyors, the moving floor system, which uses reciprocating slats to move cargo, and roller conveyor system, which uses a series of powered rollers to convey boxes or pallets.

The longest belt conveyor system in the world is in Western Sahara. It is 100 km long, from the phosphate mines of Bu Craa to the coast south of El-Aaiun. The longest single belt conveyor runs from Meghalaya in India to Sylhet in Bangladesh. It is 17 miles long and conveys limestone and shale. The Conveyor belt was manufactured in about 300 meter lengths and was joined together and installed on the conveyor at site. The job was carried out by NILOS India Pvt. Ltd. in Chennai India.

Conveyors are used as components in automated distribution and warehousing. In combination with computer controlled pallet handling equipment this allows for more efficient retail, wholesale, and manufacturing distribution. It is considered a labor saving system that allows large volumes to move rapidly through a process, allowing companies to ship or receive higher volumes with smaller storage space and with less labor expense.

Belt Conveyor Systems

Rubber Conveyor Belts are commonly used to convey items with irregular bottom surfaces, small items that would fall in between rollers, or bags of product that would sag between rollers. Belt conveyors are generally fairly similar in comstruction consisting of a metal frame with rollers at either end of a flat metal bed. The belt is looped around each of the rollers and when one of the rollers is powered (by an electrical motor) the belting slides across the solid metal frame bed, moving the product. In heavy use appliactions the beds which the belting is pulled over are replaced with rollers. The rollers allow weight to be conveyed as they reduce the amount of friction generated from the heavier loading on the belting. Belt conveyors can now be manufactured with curved sections which use tapered rollers and curved belting to convey products around a corner. These conveyor systems and are commonly used in postal sorting offices and airport baggage handling systems.

Typical Construction of a Conveyor systems Belt Bend

Belt Conveyor systems at a Packing Depot

Baggage Handling Belt Conveyor systems

Snake Sandwich Belt Conveyor

A sandwich belt conveyor uses two conveyor belts, face-to-face, to gently but firmly contain the product being carried, hence making steep incline and even vertical-lift runs easily achievable. The Snake Sandwich Belt Conveyor was created in 1979. The study was conceived by Joseph A. Dos Santos, P.E., President of Dos Santos International, with the help of a grant from the U.S. Bureau of Mines. The study was to develop a means of moving and elevating large quantities of bulk materials, including coarse products such as rocks, aggregate, coal, etc. at the steepest possible inclines. The intent was to use only existing and generally available hardware in order to achieve the most economically feasible and easily maintained steep-angle conveyor design. Snake Conveyors are available in widely ranging profiles of C and S Shape. In any case, a long bottom belt approach is possible to the sandwich entrance, and discharge may be on the high incline or may be after the extension of the carrying belt beyond the mouth of the sandwich. Snake Sandwich conveyors offer several advantages. First unlimited conveying capacity, a system suitable for the most rugged mine applications and gentle on sensitive and friable materials, high availability and low operating and maintenance costs, smooth surfaced belts allowing continuous belt cleaning by scrapers and plows. This also facilitates intermediate material discharge by belt plows, as appropriate, before and/or beyond the sandwiched part of the Snake profile. All conventional conveyor hardware insures economy and fast delivery of replacement parts.

Vibrating Conveyor Systems

A Vibrating Conveyor is a machine with a solid conveying surface which is turned up on the side to form a trough. They are used extensively in food grade applications where sanitation, washdown, and low maintenance are essential. Vibrating conveyors are also suitable for harsh, very hot, dirty, or corrosive environments. They can be used to convey newly cast metal parts which may reach upwards of 1500° F. Due to the fixed nature of the conveying pans vibrating conveyors can also perform tasks such as sorting, screening, classifying and orienting parts. Vibrating conveyors have been built to convey material at angles exceeding 45° from horizontal using special pan shapes. Flat pans will convey most materials at a 5° Incline from horizontal line.

Flexible Conveyor Systems

The flexible conveyor is based on a conveyor beam in aluminium or stainless steel, with low friction slide rails guiding a plastic multi-flexing chain. Products to be conveyed travel directly on the conveyor, or on pallets/carriers.

Pneumatic Conveyor Systems

Products are moved through various tubes via air pressure, allowing for extra vertical versatility. Pneumatic conveyors are either carrier systems or dillute-phase systems; carrier systems simply push items from one entry point to one exit point, such as the money exchanging tubes used at a bank drive-thru window. Dillute-phase systems use push/pull pressure to guide materials through various entry and/or exit points.

History

Primitive conveyor belts were used since 19th century. In 1901, Sandvik invented and started the production of the Steel Conveyor belts. In 1913, Henry Ford introduced Conveyor belt-based assembly-line in Ford Motor Company's Rouge factory in Dearborne Michigan.

See also

• Thermohaline circulation
• Treadmill
• Conveyor systems
• Lineshaft roller conveyor

External Links

• More About Belt Conveyor Systems

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