Belt conveyor; design and operating principle
The Samara Strommashina plant offers a complex of high-quality equipment for industrial production. We manufacture plants and mechanisms for a wide range of industries – mining, petrochemical, power, civil construction, pharmaceutical, agrochemical and many others. Probably, the most versatile equipment type applied everywhere is material-handling equipment, such as different conveyor types. The Strommashina offers designing and manufacturing conveyor systems of any complexity level. A belt conveyor is the main material-handling system for most of production facilities.
A belt conveyor with 200 to 1000 mm wide belt width for handling bulk materials with bulk specific gravity of up to 2000 kg/m3 (mortar sand, gravel, crushed stone, slag) along horizontal and sloped paths. A belt conveyor consists of the following components:
- conveyor frame
- SITI gear motor (Italy)
- conveyor belt
- drive tension drum
- non-driving drum
- upper carrying trough rollers
- lower flat return rollers
- deflector rollers
General design of belt conveyors.
Belt conveyors are the most popular device for continuous handling of different bulk and piece cargoes in industry and civil construction.
Typical belt conveyor diagram.
The main component of conveyor is travelling vertically-closed belt (so-called conveyor belt). Depending on the roller type, the belt shape may be flat or trough. The upper loaded and lower empty belt strands are supported by rollers. Progressive conveyor belt motion is imparted by a drive drum which is driven by a motor through a gearbox. Continuous tension is provided by means of a take-up. Load is fed onto the belt through a charging device and discharged though a drive drum funnel or at any point along the conveyor by means of special discharging devices.
The belt conveyor capacity can be brought to 20–25 cargo tons per hour at 5–8 m/s speed and 2.5–3 meter conveyor belt width. Naturally, such a capacity is not necessary in all applications; the belt width does not exceed 1 metre at most of plants. The horizontal belt conveyor length can be virtually unlimited.
Belt conveyor components
Conveyor belt is the main, most expensive component of a belt conveyor. It is both a load-carrying surface and a traction member of the conveyor. The belt consists of a rubber-textile base or steel-cord base located between rubber linings. The base supports load and transmits traction forces. The rubber linings protect the base against any mechanical damages and exposure to the environment. Rubber belt jointing can be mechanical – using brackets, lanyard clips; or it can be provided by means of hot or cold vulcanization using special glues. A butt joint strength, flexibility and durability shall be as close to such properties of the main conveyor belt material as possible. Common conveyor belt designs can be used at ambient temperature of no less than -25°C and handled material temperature no more than +60°C. Frost-resistant belts are operable up to -45°C.
Rollers are classified as linear and special rollers in terms of their function. Linear rollers are designed for supporting the belt and imparting the necessary shape to it. Special rollers carry out some other functions also. aligning – adjustment of conveyor belt position in relation to longitudinal axis; cushioning – amortization of impacts of load against the belt in charging locations; cleaning – removing any material stuck to the belt; adapting – changing fluting of the belt upstream of the drums. The roller design can vary depending mainly on type of bearings, method of their sealing and lubrication. In a three-roller idler all rollers are located in the same plane, or the middle roller is protruded forward so that to decrease the belt "jamming" and to facilitate lubrication. All idlers are installed on ball bearings. The roller diameter shall be selected depending on the belt width, belt speed and characteristics of the material to be handled.
Take-ups ensure the conveyor belt tensioning which is necessary for transmission of traction force by means of friction at the drive at steady movement and start of the conveyor, limit the belt slack between the rollers, compensate the belt lengthening as a result of the belt extension during operation and maintain some belt margin necessary for belt repositioning in case of any damage. The take-ups are classified as take-ups by gravity; load, mechanical, hydraulic and pneumatic take-ups. The most frequently used mechanical take-ups are divided into screw, spring and screw, rack and winch types. Screw-type take-ups are the most common take-up type at short stationary conveyors and mobile conveyors.
Belt conveyor drive. The main assemblies of a belt conveyor drive are:
- special-design support frame;
- drive and by-pass drums;
- braking devices;
- start and control devices.
As a rule, a single-drum drive is used at small conveyors. Driving and non-driving drums are welded design with a steel sheet shell. Sometimes drums sized up to 500 mm can be manufactured from iron casting.
Supporting metal structures. The belt conveyor support components structures are mainly made as rigid flights consisting of rolled steel or pipes, they are fabricated as separate 2 to 5-metre sections. The belt conveyor support metal structures are divided into the following assemblies:
- driving drums supports;
- middle part sections;
- middle part stands;
- tension screw device supports.
The Strommashina plant designs, manufactures and sells conveyor systems in Russia and abroad. We are ready to take care of carrying out all necessary calculations and developing the most efficient method of delivery and handling of raw material. Just phone us, and we will help you in increasing the efficiency of your production facility.