Screw Conveyor

See also: Conveyor

A screw conveyor, also known as a screw elevator, is a type of a positive displacement pump^[1] used primarily in agriculture, mining, construction, and manufacturing to move and meter fluids and granular materials.^[2]

[edit] How it Works

Screw conveyors operate on the same basic principle exemplified by Archimedes’ Screw, which was invented in the 3rd century B.C.^[3] Archimedes determined that a rotating auger fitted snugly within a cylinder could elevate water effectively. With the bottom of the screw submerged in water, the screw rotation lifts the lowest level of water to the second tier, which forces new water to flow into the now vacant bottom level. Each subsequent rotation draws in more water while elevating previous loads within the cylinder body until eventually water emerges from the top.^[4] The same principle is used today to supply aggregate to asphalt pavers, to expel grain from combines, and to break-up snow in a snow blower.^[5]

Screw conveyors can be operated vertically, horizontally, or at an angle; although they are less efficient on an angle. A conveyor on a 25-inch (63.5-cm) incline will lose 50 percent of its carrying capacity.^[6]

[edit] Types

[edit] Vertical Screw Conveyor

Vertical screw conveyors are used in bulk material handling, like agriculture, or in unit handling, like manufacturing. They are well suited for applications where horizontal space is limited; or for large, heavy loads.^[7]

[edit] Horizontal Screw Conveyor

Horizontal screw conveyors are the same as vertical screw conveyors, except they lay on their side. They are commonly used in agricultural and chemical processing^[8] for cooling, heating, mixing, de-watering, compaction, aeration, and to break up lumpy material.^[9]

[edit] Screw Feeder

See also: Feeder

A screw feeder is a type of horizontal screw conveyor. Screw feeders are characterized by their ability to constantly operate at 100 percent capacity, while horizontal screw feeders fluctuate between 40 and 50 percent capacity.  Due to their near contant output, screw feeders are commonly used to regulate the flow of material.^[10]

[edit] Flexible Auger Conveyor

A flexible auger is a type of screw conveyor whose cylindrical casing is bendable. Flexible auger conveyors are used when there are obstacles between the material source and destination, a situation which would render a normal auger unusable.

[edit] Sand Screw

See also:  Sand Screw

Sand screws are screw conveyors used to dewater sand.

[edit] Grain Auger

See also:  Grain Auger

[edit] Common Manufacturers

See also:  Conveyor Equipment Manufacturers Association

• Continental Screw Conveyor
• Conveyors Incorporated
• Drives Incorporated
• FMC Technologies
• Goodman Hewitt
• Industrial Screw Conveyors, Inc.
• KWS Manufacturing Company Ltd.
• Martin Sprocket & Gear, Inc.
• Orthman Conveying Systems
• Screw Conveyor Corporation
• Summetlot Engineered Products, Inc.
• Thomas Conveyor Company
• Wam Inc.
  

[edit] References

1. ↑ How Does Archimedes Screw Work? Blurit.com [October 5, 2009].
2. ↑ loss-in-weight feeder. Answers.com [October 5, 2009].
3. ↑ Contrasting the OLDS ELEVATOR™ with conventional screw elevators. Olds Elevator [October 5, 2009].
4. ↑ Archimedes Screw. Tiscali.co.uk [October 5, 2009].
5. ↑ Auger Products. DriveSinc.com [October 5, 2009].
6. ↑ Inclined Screw Conveyors. KWS [October 5, 2009].
7. ↑ Vertical Conveyors. Global Spec [October 5, 2009].
8. ↑ Conveyors. CICMHE [October 5, 2009].
9. ↑ Fayed, Muhammad E. and Skocir, Thomas S.. Mechanical Conveyors: Selection and Operation. Technomic Publishing Company, Inc.: 1997.
10. ↑ Application Overview: Screw Feeder. Yaskawa [October 5, 2009].