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Screw conveyor

Screw conveyor

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A screw conveyor or auger conveyor is a mechanism that uses a rotating helical screw
Screw (simple machine)
A screw is a mechanism that converts rotational motion to linear motion, and a torque to a linear force. It is one of the six classical simple machines. The most common form consists of a cylindrical shaft with helical grooves or ridges called threads around the outside...

 blade, called a "flighting", usually within a tube, to move liquid or granular materials. They are used in many bulk handling industries. Screw conveyors in modern industry are often used horizontally or at a slight incline as an efficient way to move semi-solid materials, including food waste, wood chips, aggregates, cereal grains
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

, animal feed, boiler ash, meat and bone meal, municipal solid waste, and many others. The first type of screw conveyor was the archimedian screw
Archimedes' screw
The Archimedes' screw, also called the Archimedean screw or screwpump, is a machine historically used for transferring water from a low-lying body of water into irrigation ditches...

, used since ancient times to pump irrigation water.

They usually consist of a trough or tube containing either a spiral blade coiled around a shaft, driven at one end and held at the other, or a "shaftless spiral", driven at one end and free at the other. The rate of volume transfer is proportional to the rotation rate of the shaft. In industrial control applications the device is often used as a variable rate feeder
Variable rate feeder
A variable rate feeder is a piece of industrial control equipment used to deliver solid material at a known rate into some process.A number of different techniques and transport mechanisms are used, but these broadly split into these categories, in descending order of accuracy:* closed-loop...

 by varying the rotation rate of the shaft to deliver a measured rate or quantity of material into a process.

Screw conveyors can be operated with the flow of material inclined upward. When space allows, this is a very economical method of elevating and conveying. As the angle of inclination increases, the allowable capacity of a given unit rapidly decreases.

The rotating part of the conveyor is sometimes called simply an auger
Auger
An auger is a drilling device, or drill bit, that usually includes a rotating helical screw blade called a "flighting" to act as a screw conveyor to remove the drilled out material...

.

In agriculture


The "grain auger" is used in agriculture to move grain from truck
Truck
A truck or lorry is a motor vehicle designed to transport cargo. Trucks vary greatly in size, power, and configuration, with the smallest being mechanically similar to an automobile...

s and grain carts
Chaser bin
A chaser bin, also called grain cart or auger wagon, is a trailer towed by a tractor with a built-in auger system, usually with a large capacity .- Usage :...

 into grain storage bins (from where it is later removed by gravity chutes at the bottom). A grain auger may be powered by an electric motor; a tractor
Tractor
A tractor is a vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction...

, through the power take-off
Power take-off
A power take-off or power takeoff is a splined driveshaft, usually on a tractor or truck, that can be used to provide power to an attachment or separate machine. It is designed to be easily connected and disconnected...

; or sometimes an internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

 mounted on the auger. The helical flighting rotates inside a long metal tube, moving the grain upwards. On the lower end, a hopper receives grain from the truck or grain cart. A chute on the upper end guides the grain into the destination location.

The modern grain auger of today's farming communities was invented by Peter Pakosh
Peter Pakosh
Peter Pakosh was co-founder of the Versatile tractor company, and is credited with many inventions and equipment innovations including the modern-day grain auger used by combine harvesters...

. His grain mover employed a screw-type auger with a minimum of moving parts, a totally new application for this specific use. At Massey Harris
Massey Ferguson
Massey Ferguson Limited was a major agricultural equipment manufacturer which was based in Canada before its purchase by AGCO. The company was formed by a merger between Massey Harris and the Ferguson tractor company in 1953, creating the company Massey Harris Ferguson. However in 1958 the name was...

 (later Massey Ferguson), young Pakosh approached the design department in the 1940s with his auger idea, but was scolded and told that his idea was unimaginable and that once the auger aged and bent that the metal on metal would, according to a head Massey designer, "start fires all across Canada". Pakosh, however, went on to design and build a first prototype auger in 1945, and 8 years later start selling tens of thousands under the 'Versatile
Versatile
Versatile is a Canadian brand of agricultural equipment that has produced augers, swathers and combine harvester.In the 1970s, it was an independent operation, founded by Peter Pakosh and Roy Robinson, that had 70% of the 4WD tractor market and then was later owned by Ford and Fiat's New Holland,...

' name, making it the standard for modern grain augers.

A specialized form of grain auger is used to transfer grain into a seed drill, and is usually quite a lot smaller in both length and diameter than the augers used to transfer grain to or from a truck, grain cart or bin. This type of auger is known as a "drill fill". Grain augers with a small diameter, regardless of the use they are put to, are often called "pencil augers".

Other uses


Various other applications of the screw or auger conveyor include its use in snowblowers, to move snow towards an impeller
Impeller
An impeller is a rotor inside a tube or conduit used to increase the pressure and flow of a fluid.- Impellers in pumps :...

, where it is thrown into the discharge chute. Combine harvester
Combine harvester
The combine harvester, or simply combine, is a machine that harvests grain crops. The name derives from the fact that it combines three separate operations, reaping, threshing, and winnowing, into a single process. Among the crops harvested with a combine are wheat, oats, rye, barley, corn ,...

s use both enclosed and open augers to move the unthreshed crop into the threshing mechanism and to move the grain into and out of the machine's hopper. Ice resurfacer
Ice resurfacer
An ice resurfacer is a truck-like vehicle or smaller device used to clean and smooth the surface of an ice rink. The first ice resurfacer was developed by Frank J. Zamboni in 1949 in the city of Paramount, California...

s use augers to remove loose ice particles from the surface of the ice. An auger is also a central component of an injection molding machine
Injection molding machine
An Injection molding machine, also known as an injection press, is a machine for manufacturing plastic products by the injection molding process. It consists of two main parts, an injection unit and a clamping unit....

. An auger is used in some rubbish compactors to push the rubbish into a lowered plate at one end for compaction.

Augers are also used to force food products through dies to produce pellets. These are then processed further to produce products such as bran flakes. Augers are also used in oil fields as a method of transporting rock cuttings away from the shakers to skips. Augers are also used in some types of pellet fed barbecue grills, to move fuel from a hopper into the firebox in a controlled manner. Augers are often used in machining
Machining
Conventional machining is a form of subtractive manufacturing, in which a collection of material-working processes utilizing power-driven machine tools, such as saws, lathes, milling machines, and drill presses, are used with a sharp cutting tool to physical remove material to achieve a desired...

, wherein the machine tools may include an auger to direct the swarf
Swarf
Swarf, also known as turnings, chips, or filings, are shavings and chippings of metal — the debris or waste resulting from metalworking operations including milling and grinding. It can usually be recycled, and this is the preferred method of disposal due to the environmental concerns regarding...

 (scrap metal or plastic) away from the work piece.

See also



  • Spiral separator
    Spiral separator
    The term spiral separator can refer to either a device for separating slurry components by density, or for a device for sorting particles by shape...

  • Screw-propelled vehicle
  • Archimedes' screw
    Archimedes' screw
    The Archimedes' screw, also called the Archimedean screw or screwpump, is a machine historically used for transferring water from a low-lying body of water into irrigation ditches...


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