BELT CONVEYOR SYSTEM

What is a belt conveyor system?

A belt conveyor system is the best and simplest material handling system. It consists of two or more pulleys at each end, one of which is driving and the other is driven, with a closed loop of conveyor belt around them and rotates with the driving pulley.

The reason it has been used in most of the applications are:

  • It is one of the cheapest, most efficient and stable ways to move material long distances
  • No risk of damage to the material being conveyed
  • Conveyor pathways can be designed with changes in elevation, inclination and required orientation
  • Many loading and unloading options are available
  • Material conveyed can be scanned and weighed easily
  • Can save space and increase production capacity with no additional space required
  • Low maintenance cost

Types:

There are five main types of belt conveyor systems-

Roller bed conveyor, flatbed conveyor, modular belt conveyor, cleated belt conveyor, troughed bed conveyor

    1. Roller bed belt conveyor- it is a conveyor that uses several rollers set up on the fixed support according to a certain distance to transport goods. These are used when the material loads are heavier for longer distances, like airport luggage sorting and cargo transportation.
    2. The flatbed conveyor has the general structure and characteristics of the belt conveyor, which is suitable for transporting irregular shapes and lightweight objects.
flatbelt
belt

 

    1. Modular belt conveyor – while a flat belt conveyor uses a single, continuous loop of belt, a modular conveyor uses a single loop of countless interlocked rigid pieces. It can be used in a wide range of temperature and PH levels, making it an ideal choice for the food industry and fluid handling.
    2. Cleated belt conveyor – these will always have a vertical cleats or barriers to separate equal segments on the belt. These segments keep loose material that might otherwise roll back or fall off the conveyor during inclines and declines. It is used in coal, grain, building construction, chemical and metallurgy industries.

 

  1. Trough belt conveyor – these types have a large loading and conveying capacity and high-speed requirements. In this type, carrying side belt is supported by troughed idlers composed of central roller and the outer two rollers at an angle. The angle is usually around 20 to 45 degrees. It is widely used in mining, recycling plants, cement, feed processing plants.
belt conveyor

COMPONENTS:

components

A standard belt conveyor system has belt, pulleys, idler rollers, motor & gear box, conveyor frame and cleats & sidewalls.

Conveyor belt – it is the most intricate part of conveyor system. The tension and strengths are important since the belt takes lot of punishment when loading and ferrying the material. There are 5 main conveyor belt types namely solid belts, filter belts, woven metal belts, hinged belts, plastic interlocking belts.

Head pulley – the head pulley is the driving pulley which is coupled with the gear box or motor. It is mostly located at the discharging end so as to create pulling force rather than pushing. To increase its traction with the belt, it will usually have the largest diameter of all pulleys and have a rough jacket covering its outer surface.

Tail or return pulley – this is the driven pulley and is located at the loading end of the belt conveyor. It is mostly mounted on the slotted guides to allow belt tensioning.

Snub pulley – it is used to increase the wrap angle of the conveyor belt along head and tail pulley which then reduces the belt tension and pulling force of the belt.

Idler roller – these rollers are employed along the length of the belt to support, prevent sagging, and aligning the belt. There are different types of idler rollers like troughing idlers, rubber disc idlers, trainer idlers.

Conveyor frame – the frame depending on the loading, height of operation and distance to be covered will vary. They can come in a simple setup that can be represented by a cantilever or trusses in the case of larger loads.

Cleats & sidewalls – cleats & sidewalls are usually used to transport goods on an inclined conveyor. It prevents material from falling off or rolling back on high inclines.

Take-up – it is a key component in maintaining proper belt tension, which ensures evenly belt wear, material is contained and mechanical stability. The primary types of belt conveyor take-up are the screw take-up, gravity take-up, and horizontal take-up.

Screw take-up – it utilizes mechanical force by adjusting a threaded tensioning screw integrated into the conveyor frame which can either be pushed outward or pulled inward on each side of the tail pulley.

Gravity take-up – it utilizes three pulleys (two bend pulleys and one sliding pulley) to automatically manage belt tension. A counter weight attached to the sliding pulley pulls down the belt to maintain tension via gravity.

Horizontal take-up – it is similar to gravity take-up, but instead of the assembly situated below the belt, it is positioned vertically behind the tail pulley which eliminates any additional space under the conveyor.

components
COMPONENTS:
Truss

Structural support and walkways along belt conveyor:

Truss – it is integrated with the conveyor frame and is used when there is need for large spans and to ensure great durability and strength.

Trestle – it is a structural framework consisting of horizontal and diagonal beams supported by two pairs of sloping legs to support conveyor at heights

Walkway – walkways are designed to bolt to the conveyor supports of channel frame conveyors, or directly to the lower cord angles of truss sections. The handrails may either be welded directly to the walkway support frame, or may be designed to bolt together.

Design parameters:

If we are designing a conveyor system layout, we will need the following details to proceed:

  • Site plan with suitable contour drawings and over/under surface interferences
  • Details of loading and unloading points
  • Material characteristics, including type and size analysis
  • Material flow diagram and flow rates
  • Conveyor length, lift, support span, cover requirement and walkway requirement if any

Once the configuration and layout of a conveyor are finalized, we determine:

  • Type of conveyor most suitable
  • Motor and gearbox selection, along with acceleration and deceleration
  • Belt selection
  • Idler selection and its spacing
  • Pulley and shaft diameter
  • Operating belt speed
  • Belt width
  • Belt tension and take up
  • Structural design calculations (truss and trestle)
  • Proposed walkway along the conveyor