The basic elements of the belt conveyor are:
|1. Belt and belt-tightening system |
2. Belt drive and power supply
3. Roller supports for belt
4. Feeding arrangement
5. Discharge arrangement
- Horizontally or inclined placed motor-driven rotating belt on pulleys convey the material from feeding point to discharge point.
Construction of Belt Conveyor:
- The construction of a belt conveyor is shown in Figure. Belt conveyor consists of a core or carcass of several piles of cotton duck, each layer is impregnated and bonded with rubber The carcass is then covered with a thin layer of rubber that binds the piles together. Both ends of the belt are joined together so that the belt can revolve continuously. The belt may run horizontally or slightly inclined from the feed point.
- If the belt is too thin for its width, it will sag between idlers.
- If the belt is too thick, it does not trough properly.
- Sometimes, the length of the belt is increased due to a variety of factors such as temperature and humidity of the ambient. In such cases, it is necessary to keep the belt taut. Hence, tighteners (or take-up) are installed to maintain even tension on the belt under all conditions. The simplest take-up consists of a cast iron bed with a traveling block moving along a screw.
- The belt is allowed to move with the help of a belt drive. The simplest belt drive is a bare steel pulley actuated with some source of power. The drive of the belt conveyor is fixed at the discharge end (It is rarely arranged at the feed end). There should be appropriate contact between the belt and pulley. Introducing snubber idlers just below the pulley can increase the contact.
- The belt is supported by rollers, which are arranged on a shaft. These are called idlers. The idlers are carried on bush bearings lubricated with grease cups. The idlers are generally troughed to depress the belt at the center and rise at the edges (Figure – 2c). This permits the belt of a given width to carry more material per linear meter without spillage. The belt returns on ordinary, non-troughing rolls.
- A hopper is placed at one end in such a manner to load the teed at the center of the belt. Cleaning devices such as revolving brush and rubber scraper blades are placed in the path of the belt to clean if the material sticks to the belt. Provision is made at the other end for discharging.
Working of Belt Conveyor:
- When power is applied to a conveyor, the belt starts rotating. As the pulley moves, the belt begins to travel in a forward direction, because of its close contact with the pulley. Snubber idlers also help in maintaining close contact between the pulley and belt.
- The material (to be transported) is loaded on its center of the belt with the help of a hopper. The material travels along the belt. The belt moves forward on troughing idlers. This permits the belt to carry more material per linear meter without spillage. The amount of feed delivered depends on the width and speed of the belt. At the discharge end, the material may be unloaded manually or mechanically.
- Once the material is unloaded, the belt returns on lighter non-troughing rolls to the point of feeding.
- Belt conveyors are used in transporting containers for Lilling, capping, sealing, labeling, pasting, visual inspection, etc., in the production of injectables, liquid orals, ointments, and jellies.
- In the strip and blister packings of tablets and capsules. strips are conveyed on a moving belt. During this process, the strips are packed in the cartons.
- Belt conveyors are used in the manufacture of lozenges. It is a continuous process of candy base cookies. When a mass of sugar base is on the conveyor the water is removed. At the end of the belt, the candy base is mixed, tempered, formed, roped, melted, acidulants, and flavors are added. cooled and sized.
Advantages of Belt Conveyor:
- Belts can be made of asbestos fibers, neoprene, Teflon, and vinyl polymer. Cord belts are also used.
- Beli conveyors are for general-purpose installation and available in relatively large sizes. These can travel several kilometers as in the case of coal mines.
- Routine maintenance of the belt conveyor is easy.
- Belt conveyor is economical in terms of cost per unit tonne that it can handle.
- Belt conveyor is expensive.
Selection of Belt Conveyor:
- The capacity of a belt conveyor depends on the cross-section of the load and the speed of the belt. The cross-section of the load depends on the width and slope of the belt and the size of the material. The selection of a belt conveyor depends on:
- Power required.
- Mechanical and tensile strength of the belt system to handle the wide varieties of materials.
- Lump size.
- Troughability of the belt.
- The ability of the belt to support the load between idlers.
- Chemical resistance of the belt to the material to be handled.
Manufacturers of belt conveyors publish charts or formulae for the construction of conveyors, size, and power requirements.
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