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Vibrating Screens
Vibrating screens are a type of vibratory conveyor that conveys and/or sorts bulk materials during processing. The main difference between a typical vibratory conveyor and a vibratory screen is that a vibratory screen runs materials over a sizing screen instead of a trough. Also known as a screen separator, vibrating screens are commonly used to separate smaller particles from larger particles for further processing. Additional applications for vibrating screens include coal dressing, removing unwanted materials, washing, classifying and grading materials. Used in a wide variety of industries, including mining, construction, energy, chemical processing, electrical, petroleum, wastewater, metallurgical, transportation and agriculture, vibratory screen systems are easy to maintain and offer a long bearing lifetime. Able to handle wet or dry materials, typical materials that undergo vibratory screening include wood wastes, glass, food products, gypsum, scrap tires, plastics, chemicals, minerals, aggregates and foundry materials. Vibrating screens can be multi-layered and are commonly constructed from either high grade stainless steel or spring steel, ensuring strong handling capabilities and reliability. Some advantages of using vibrating screens are: low energy consumption per ton of screened material; a simple construction, making it easy to change screen layers; and the high force of vibration reduces the chance of materials blocking the screen, thus increasing screen productivity and efficiency. Vibrating screens typically consist of a screening body, vibrators, a suspending device, also referred to as a supporting device, and an electric motor. The screening body in a vibrating screener is often constructed from materials such as stainless steel mesh, nylon, synthetic monofilament cloth, standard market grade or tensile bolting cloth and bar screens. The screening body is connected to a tray; materials enter the vibrating screen through a feed box located at the base of the tray. The vibrators are often either electromagnetic or electromechanical, and are placed at intervals underneath the screening body. While electromechanical vibrators are more common and simpler in design, electromagnetic vibrators offer a smoother conveying motion. The suspending device supports the structural framework that the screens are mounted on and are typically springs such as leaf springs or steel coil springs. These springs serve as shock absorbers as well as ensuring that the vibrations occur at a natural frequency. Roller bearings, shafts or couplings are used to provide a circular, elliptical or linear vibrating motion. In addition, an electric motor is attached to the structural framework and causes the materials to be vibrated in a specific direction. There are two sub-types of vibrating screens: circular vibrating screens and trommel screens. Circular vibrating screens have a circular vibrating screen track which is especially designed for screening stock stone quarry as well as classification applications. Trommel screens are vibrating screens which help sort small particles from large particles, which are typically used in the recycling industry since they cut down on the huge amount of labor required to sort recyclable material.
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