Introduction

Drums are rotating components found in belt conveyors that have the function of transmitting movement, diverting direction or even stretching the belt. This equipment is made up of four main structural components: the shaft, the hub, the disk and the cylinder. Figure 1 shows the distribution of these elements in a drum.

Figure 1: Drum components - SOURCE: https://www.exctmach.com/products/spare-parts/conveyor-pulley.html

In addition, the drums also consist of expansion rings, which are commonly used to connect the shaft to the hub, and bearing housings, which are responsible for enabling the rotational movement of the drums. For this reason, the bearing is selected first, and based on that selection, the bearing housing is chosen, since each bearing requires a specific housing. Furthermore, the bearings and bearing housings are selected based on minimum fatigue life requirements and in accordance with the load limits of the bearings.

Types of drums

Drums serve different functions in a belt conveyor depending on their position, such as creating deflections and bends in the belt. Thus, we can define several classifications for this component, including:

1. 1. Return: located at the opposite end to the discharge terminal, its function is to return the belt to its initial position, and it can also act to tension the belt;

1. 1. Stretcher: responsible for maintaining the ideal tension for the conveyor to function properly;

1. 1. Drive: responsible for transmitting torque. This type of drum can be located at the discharge, center or return of the conveyor;

1. 1. Deflection: its function is to deflect the belt's travel;

1. 1. Backrest: its function is to increase the angle at which the belt grips the drive drum;

Design and applications

When sizing this type of equipment, the most important information is the width and tension of the belt, as well as the type of construction. As shown in Figure 2, the discs can be manufactured integrally and welded to the cylinder, or they can be welded to the hub and cylinder. The drum must be dimensioned taking into account the positions and types of weld, as well as the stresses required in each position.

Figure 2: Types of drum construction - SOURCE: Kot Collection.

In general, this equipment is made of steel and, as already mentioned, one of its main functions is to drive the belt so that the conveyor operates as intended. In this case, the drum used is the drive drum, which is connected to the drive assembly, consisting of motors and gearboxes. In some cases, when necessary, a brake disc can also be attached to the drum shaft to be used in conjunction with the conveyor’s braking system.

For operations where high belt tensions are required, different drive configurations can be used. Among them, the use of a drive assembly on more than one drum can be considered, as well as the use of a double drive on the same drum.

Next, in Figure 3, you can see the braking system on a belt conveyor, as well as a double-drive drum.

Figure 3: Braking system on conveyor with double drive drum - SOURCE: https://www.mining-technology.com/contractors/crushers/johnson-industries/.

Due to the various applications of this equipment in belt conveyors, which in turn use a variety of loads, its calculation and sizing in projects is done according to the load capacity of each conveyor. Its manufacture also follows the technical standards and norms applicable to this type of equipment.

In addition, another key component in the use of drums is the lining, which is designed to protect the equipment from wear and tear and also increase its traction capacity. In this context, given the wide variety of designs, many factors must be considered when choosing a drum for your conveyor belt, such as the cost of the equipment, the environment in which it will be installed, ease and cost of maintenance, as well as, of course, the conveyor belt’s operating parameters, such as tension, wrap angle, number of start-stop cycles, belt speed, among others. Figure 4 shows some lining models, which will be selected according to their intended use.

Figure 4: Types of cladding - SOURCE: https://www.bocril.com.br/index.php?id=servicos2&cod=43

Market advantages

Currently, with the market constantly growing, new opportunities are emerging for the design and application of this component in environments that require greater capacity, efficiency, or even safety. As a result, this drives the continuous development of technologies, with new coatings, dimensions, and geometries that are increasingly tailored to the specific needs of each application.

Above all, one of the main advantages of using drums is in the long-distance transport of materials, as the use of conveyor belts leads to significant cost savings. This is achieved by reducing the number of trucks used to transport materials, thereby reducing the overall workload. Likewise, it is possible to reduce employees’ direct interaction with the material transport process and with the material itself, which enhances operational safety. Additionally, another benefit of using conveyor belts is improved control of particulate emissions. Some methods applied to conveyor belts for this purpose are presented below:

1. 1. Enclosure of conveyor belts: prevents dust being drawn in during material transfers;

1. 1.  Application of dust suppressant: this product forms a film around the material, reducing dust emissions;

1. 1. Dedusting system: responsible for filtering the air before particles are released into the atmosphere;

Another factor to pay attention to is the conformity of the drums with the conveyors on which they will be used. It is essential to check that the drums and belts are compatible, thus avoiding subsequent adjustments to the initial design, or even rework to adapt the components.

Conclusion

In summary, drums are rotating components that are subjected to high cycle counts and heavy loads resulting from belt tension. Furthermore, welding processes are inherent to the construction of this equipment, and it is well known that such processes create regions where crack initiation is favored. Therefore, it is essential that drum designs offer high reliability, taking into account proper manufacturing and sizing procedures based on applicable standards, thereby preventing fatigue failures in both the structure and its components, and increasing the equipment’s service life and productivity.

In conclusion, the importance of drums for the operation of belt conveyors is clear. Special attention must be paid to the maintenance and management of these components to prevent production downtime and ensure operational efficiency and safety at all times. The drum assembly comprises various parts, so failures in individual components—such as the bearing or expansion ring—can compromise the entire system’s operation. Therefore, conducting inspections and structural assessments ensures greater equipment reliability, providing higher productivity and predictability for the maintenance of these assets.

Kot Engenharia extensive experience in performing services involving drums and belt conveyors, ranging from finite element analysis to drum failure analysis, as well as proposing design improvements.

If you have any needs regarding inspections and structural solutions, we have a specialized workforce to assist your business. Consult our team for more information!

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References

1. 1. THE FUNCTION AND MECHANISM OF CONVEYOR PULLEY DRUMS - Terry J King Pr. Eng.

1. 1. Faço Continuous Conveyor Manual, Ed. Faço, 1996.

1. 1. CEMA Manual (Conveying Equipment Manufacturers Association), version 93.

1. 1. Conveying Machines, Spivakovisky and Diaachkov, Editorial Mir, 1989.

1. 1. Transportation and Elevation, P. Alexandrov, Ed. Mir, 1994.