Lecture 4 Material Handling Equipment (Conveyors)

Material Handling Equipment Lecture - 4 out of 5

1. MATERIALS HANDLING EQUIPMENT Lecture Four Conveyors Outlines Introduction Belt conveyors Oscillating conveyors Chain conveyors By: Amanuel D. 06-Sep-19 1 By: Amanuel Diriba

2. Definition A conveyor is a mechanized device to move materials in relatively large quantities between specific locations over a fixed path. Conveyor is e quipment used to move materials over fixed path between specific points. Conveyors are used : When material is to be moved frequently between specific points. To move materials over a fixed path When there is a sufficient flow volume to justify the fixed conveyor investment 06-Sep-19 2 By: Amanuel Diriba

3. Cont.. Benefits of Conveyors Automation of the flow of products Continuous flow of materials May be set up almost any place Can be utilized to move almost anything Improve safety, order accuracy, labor cost Shorten time from order to shipment Conveyors can be classified in different ways : Type of product being handled: unit load or bulk load Location of the conveyor: in-floor, on-floor, or overhead Whether loads can accumulate on the conveyor or no accumulation is possible 06-Sep-19 3 By: Amanuel Diriba

4. Some types of conveyors are :- 1. Chute conveyor 2. Wheel conveyor 3. Roller conveyor 4. Chain conveyor 5. Slat conveyor 6. B elt conveyor 7. Magnetic belt conveyor 8. Troughed belt conveyor 9. Bucket conveyor 10. Vibrating conveyor 11. Screw conveyor 12. Pneumatic conveyor 13. Vertical conveyor 14. Cart-on-track conveyor 15. Tow conveyor 16. Trolley conveyor 17. Power-and-free conveyor 18. Monorail 19. Sortation conveyor 20. Oscillating conveyors 06-Sep-19 4 By: Amanuel Diriba

5. Belt conveyors A belt conveyor consists of an endless flat and flexible belt of sufficient strength, made of fabric , rubber, plastic, leather or metal, which is laid over two metallic flat pulleys at two ends, and driven in one direction by driving one of the two end pulleys. The endless belt is kept taught by a belt tensioning arrangement 06-Sep-19 5 By: Amanuel Diriba

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7. Cont.. Belt conveyors occupy an outstanding position in the field of bulk material handling . They are the most multipurpose and widely used of all conveyors The range of sizes, which may be handled, is limited only by the width of the belt. They can handle a wide range of capacities over longer distance than possible with other types of conveyors system. Many varied arrangements or paths of belt conveyors are possible. They can be any combination of horizontal ascending or descending path. 06-Sep-19 7 By: Amanuel Diriba

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9. Cont.. Belt conveyors are the mostly used for transport of solid objects and bulk materials at great speed, covering great distances (up to 30 km) General Characteristics Belt conveyors operate in one horizontally or with an inclination (up or down ) depending on the frictional property of the load conveyed. For changing direction of the materials being conveyed, in the horizontal plane, more than one belt conveyors are needed. Conveying capacity of a conveyor can be controlled by changing belt speed. Belt conveyors are generally employed for continuous flow of materials. Metal/special belts can carry hot, abrasive or reactive materials 06-Sep-19 9 By: Amanuel Diriba

10. Cont.. Advantages of Belt Conveyor Silent continuous transport. Require less manpower. Economical, low power consumption. Require simple arrangements both at loading and unloading ends. Low maintenance cost. Multipoint loading is convenient. 06-Sep-19 10 By: Amanuel Diriba

11. Cont.. Disadvantages Vertical transportation can not be done. A separate arrangement for material handling is required. Hot materials can not be transported. High initial cost for short distances. Not suitable for shorter distance and inclination > 20º Not suitable for dust particles and slurry. 06-Sep-19 11 By: Amanuel Diriba

12. Belt conveyors components The belt conveyor is composed of the belt, the idlers, the pulleys, the driven equipment, the take-up and the supporting structure. 06-Sep-19 12 By: Amanuel Diriba

13. Cont.. Conveyor belting The belt is an endless moving rubber covered conveyor for transporting materials. The belt conveyor is made of special wear and impact resisting rubber compound with cord breaker strip impeded in tough rubber. 06-Sep-19 13 By: Amanuel Diriba

14. Cont.. Belt idlers The idlers are used to carry and train the belt. Idlers must be selected to properly protect and support the belt and load to be carried. The types of belt idlers with in the series include 20 degree and 45 degree toughing cushion, belt training, flat belt and return idlers. 06-Sep-19 14 By: Amanuel Diriba

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16. Cont.. Drives T he drive equipment used for transmitting power from the motor to the driving pulley or pulleys . Practically all belt conveyors are driven by an electric motor directly connected to a speed reducer unit through a flexible coupling. 06-Sep-19 16 By: Amanuel Diriba

17. Cont.. Take – ups The take – ups used to maintain the slack side tension Every belt conveyors must be equipped with a take – ups to: Allow for stretch and shrinkage of the belt due to variation of temperature and atmospheric pressure. Insure that the maximum tension in the belt is sufficient to prevent undue sag between idlers. Insure that the tension in the belt in the back of the drive pulley is sufficient to permit such pulley to transmit the load. 06-Sep-19 17 By: Amanuel Diriba

18. Cont.. The basic types of take – up used for belt conveyors are automatic counter weighted types(a and b) and manually adjusted screw types (c) for vertical or horizontal travel. 06-Sep-19 18 By: Amanuel Diriba

19. Cont.. Pulleys, shafts and bearings The pulleys with their shafts and bearing used to drive the belt and change its direction of travel. Supporting structure The structure is which supports and maintain alignment of idlers, pulleys and the drive. The adhesion ( wheel grip) between the belt and the driving pulley can be increased by Changing the pulley Increasing the arc of contact Using stretchers(take – ups) 06-Sep-19 19 By: Amanuel Diriba

20. Types of B elt conveyors Flat Belt Conveyor : In this conveyor, the active side of belt remains flat supported by cylindrical rollers or flat slider bed. The conveyor is generally short in length and suitable for conveying unit loads like crates, boxes, packages, etc . in manufacturing, shipping, warehousing and assembly operations. 06-Sep-19 20 By: Amanuel Diriba

21. Cont.. (b) Troughed Belt Conveyor : In this conveyor, comparatively wide flat belt is supported on troughed carrying rollers or shaped supporting surface so that the two edges of the active side of the belt are elevated from the middle part to form a trough. This provides a greater carrying capacity than a flat belt of equal width for conveying bulk materials or those materials which would slide off flat belts. These conveyors are used in handling bulk materials of different classes. 06-Sep-19 21 By: Amanuel Diriba

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23. Cont.. (c) Closed Belt Conveyor: In a closed belt conveyor, the specially fabricated belt, after being loaded with the material, can be wrapped completely around the load. It essentially forms a closed tube moving along with the material. The advantages of a closed belt conveyor are: it can handle fragile materials safely and without breaking by reducing inter particle collision, it can handle fine bulk materials without being swept by air (however, it is not really air tight at loading and unloading points), ability to handle corrosive and reactive materials without contamination and the tubed belt can travel around bends in more than one plane 06-Sep-19 23 By: Amanuel Diriba

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25. Cont.. (d) Metallic Belt Conveyor: This is a flat belt conveyor where the flexible belt is replaced by a cold rolled carbon or stainless steel strip belt of thickness from 0.6 mm to 1.2 mm. Metallic strip belt conveyors are used in food, chemical industry and for conveying hot and reactive loads. Wire-mesh belts are being widely used to handle unit and lump materials through furnaces (up to 1000°C temperature), as mobile base for baking industry and also for wetting, cooling, dehydrating and similar operations. 06-Sep-19 25 By: Amanuel Diriba

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27. Cont.. (e) Portable Conveyor: Short length flat conveyors carried on a wheeled structure is termed portable conveyor. These are particularly useful for loading and unloading of trucks / transport vehicles. The inclination of the conveyor can generally be adjusted to suit application . 06-Sep-19 27 By: Amanuel Diriba

28. Cont.. (f) Chain or Rope Driven Belt Conveyor: In which the specially designed belt is driven by a moving chain or rope, where belt only serves as load carrier, and motion is by a chain or rope conveyor 06-Sep-19 28 By: Amanuel Diriba

29. Cont.. (g) Submerged Belt Conveyor : In which a portion of the belt moves through a metallic trough (casing) which is filled with free flowing, powdered material at the loading end. The moving belt with holes, makes the material flow to the unloading end of the trough. 06-Sep-19 29 By: Amanuel Diriba

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31. 2. Oscillating conveyors A type of vibrating conveyor having a relatively low frequency and large amplitude of motion Oscillating conveyors move materials in a uniform, continuous flow by the upward and forward oscillating motion of a continuous metal trough, mounted on robust inclined reactor legs. The angle of α Inclination of the conveyor arm may vary from 25 to 30degree . The movement of the conveyor follows harmonic motion and is governed by the equation. 06-Sep-19 31 By: Amanuel Diriba

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33. Cont.. Advantages of Oscillating Conveyors: simple construction and easy maintenance, high strength and hard mining conditions resistance, relatively low investments costs, easy to disassemble, move and assemble, easy and quick extension and shortening of trough, safety , Disadvantages of Oscillating Conveyors: unable to lift material (above 4° ineffective), moving of material causes its attrition and increases dust, poor efficiency . 06-Sep-19 33 By: Amanuel Diriba

34. Types of oscillating conveyors There are basically three types of oscillating conveyors for light, medium and heavy duty service. Flexmount oscillating conveyors They are used for light duty applications. They have simple construction, remarkably rugged, compact and require minimum maintenance and attention . Coilmount oscillating conveyors They are used for medium duty service. They are rugged, well strengthened and require minimum maintenance. The coil springs operate in the natural frequency rang. 06-Sep-19 34 By: Amanuel Diriba

35. Cont.. Torqmount oscillating conveyors They are used for heavy and extra duty applications . They are rugged, dependable and easy to adjust and maintain. Torsion bars fixed at one end and steel backed rubber bushed at the other end, absorb the energy of the trough movement at the end of the stroke at all points of support along the trough length. 06-Sep-19 35 By: Amanuel Diriba

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37. 3. CHAIN CONVEYORS A chain conveyor is a machine that transfers material or objects from one point to another by means of a moving chain. The conveyor chain is driven by a head sprocket or roller, also called a drive wheel. A conveyor chain may have plates, blocks or bars attached to it which are designed to fastener, push or drag the object or material which is to be moved . Chain conveyors are used for moving products down an assembly line and/or around a manufacturing or warehousing facility . Chain conveyors are generally easy to install and have very minimum maintenance for users 06-Sep-19 37 By: Amanuel Diriba

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40. Cont.. Chain, compared to belts of a belt conveyor, have certain advantages as well as disadvantages. The major advantages are:- The chain easily wrap around sprockets of small diameter, and the drive is positive. No slippage takes place between chain and sprocket. The chain stretch is also little. The disadvantages of chain are:- Its high weight, High initial cost, Higher maintenance cost and Limited running speed 06-Sep-19 40 By: Amanuel Diriba

41. CHAIN CONVEYOR APPLICATIONS Transporting heavy products from one location to another. Moving product through high temperature zones, for instance through ovens where other conveyor types may not be suitable Conveying of products in either continuous or indexing modes (i.e. the chain stops and starts each time to move a product to the end of the chain using a sensor) Changing the speed is necessary. Importantly when fitted with a VFD (variable frequency drive), a chain conveyor is a simple conveyor to adjust the speed on. 06-Sep-19 41 By: Amanuel Diriba

42. Types of Chain Conveyors 06-Sep-19 42 Apron or Pan Conveyor: This is the most common type of chain conveyor. It consists of one or more strands of endless chain, usually link plate roller type, running in steel guides. The carrying surface of the conveyor is composed of a series of plates or shapes called apron , which are attached to the links of the chains through cleats. By: Amanuel Diriba

43. 06-Sep-19 43 By: Amanuel Diriba

44. Cont.. (b) Cross-Bar Conveyor : This type of conveyor consists of a single or two strands of endless chain , to which are attached spaced, removable or fixed arms (or cross members) from which materials are hung or festooned. The arms may be replaced by shelves/trays to support packages or objects to carry them in a vertical or an inclined path. 06-Sep-19 44 By: Amanuel Diriba

45. Cont.. (c) Car-Type Conveyor: This type of conveyor consists of a series of small platform cars, propelled by an endless chain, running on a closed track . Car-type conveyors may have vertical runarounds over sprockets having horizontal axis. However, more often they are designed with horizontal runarounds (carousels) over sprockets (or sheaves for rope drive) with vertical axis. This type of conveyor is also called a carousel conveyor or a pallet-type conveyor . 06-Sep-19 45 By: Amanuel Diriba

46. Cont.. (d) Carrier chain & Flat-top chain conveyor: Carrier chain conveyor consists of one or more number of endless chains to which may be attached one of the many different attachments for the purpose of carrying unit materials or objects. In many cases, the materials are conveyed while being directly in contact with the chain/chains. Different designs of attachments are used for different types of materials 06-Sep-19 46 By: Amanuel Diriba

47. Cont.. (e) Trolley Conveyor : These conveyors consist of a series of trolleys supported from an overhead endless track and propelled by an endless chain or cable, with the loads usually suspended from the trolleys. This is one of the most multipurpose type of chain conveyors which can work in horizontal and inclined paths, vertical curves and horizontal turns to follow complicated routes 06-Sep-19 47 By: Amanuel Diriba

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