Causes of conveyor belt drum failure and ways to resolve them

A belt conveyor is a continuous-action conveying machine that serves both as a belt‑driving mechanism and as a load‑supporting system. It offers high conveying capacity, low operating resistance, low energy consumption, and simple maintenance, making it widely used for surface and underground transportation in coal mines. The drum is the primary component of the belt conveyor, and its service life significantly affects the conveyor’s normal operation and productivity. This paper begins with an analysis of the drum’s structure and loading conditions, summarizing improvement methods to enhance the drum’s durability.
1. Structure and operating principle of the drum
In conveyor systems, drums can transmit traction force and also change the direction of belt movement. Based on the manufacturing process, they are classified into welded drums and cast‑welded drums; according to their function, they are divided into drive drums and idler drums. High‑power drive drums (≥360 kW) use cast‑welded drums, while all other applications may employ welded drums. A drum consists of a shaft, a drum body, and two end plates. The end plates are cast components, and the drum body is fabricated from steel plates. During operation, the shaft is connected to the end plate, the joint is welded to the disc, and the driving force is transmitted to the roller’s shaft, which drives the overall rotation of the drum, thereby setting the belt in motion. Its transmission principle is based on friction—utilizing the friction between the drive drum and the conveyor belt to couple the drive mechanism to the belt, thus completing the energy transfer and ensuring reliable belt operation.
2. Analysis of the causes of drum failure and influencing factors
(1) Analysis of the cause of failure
The belt exerts high pressure on the drum, and under prolonged high stress, the drum is prone to rupture. Cracks often develop irregularly along the shaft, extending from the weld side of one belt to the weld side of the opposite belt. The main causes of failure are as follows: First, the belt operates under high tension. Because tension is elevated and traction is strong, conveyors frequently seek to enhance transmission capacity by increasing tension, which inevitably raises the drum’s stress. Furthermore, as rotational speed increases, the torque acting on the drum also grows, leading to bending and deformation of the drum and its components. Combined with adverse underground conditions, this can result in drum fracture. Second, insufficient drum strength—due to poor‑quality steel plate or inadequate thickness—can also lead to cracking. Third, substandard welding procedures and poor weld quality may likewise cause cracks. Since the drum’s structure relies heavily on welding, residual welding stresses arise during operation. If these are not properly managed, cracks will quickly appear in the welds under stress.
(2) Various factors that affect drum failure
Roller wear reduces strength and also makes drums prone to cracking. The main influencing factors are: (1) The impact of contamination on wear. Wear caused by coal dust and dirt on the belt and drum surfaces is typical abrasive wear. This friction often produces characteristic spalling and cavities on the damaged drum surface, and surface‑impact‑induced fatigue effects occur. Furthermore, chemical action in liquid or gaseous environments—especially at high temperatures—accelerates wear, reducing the drum’s strength; (2) The effect of the wrap angle on wear. Increasing the wrap angle improves traction on the drum surface and reduces wear, but the wrap angle should not be excessively large; otherwise, it will exacerbate flexural fatigue and belt failure; (3) The effect of the coefficient of friction on wear. Raising the coefficient of friction is the most effective way to reduce wear. Currently, efforts are underway to develop materials with high coefficients of friction, stable performance, excellent wear resistance, and high specific pressure resistance for use as drum linings.
3. Solutions
(1) Select high-quality materials to enhance manufacturing quality and ensure drum durability.
(2) Increase the thickness of the steel plate on the drum and evenly arrange several axial reinforcing ribs inside the drum. This can be achieved by calculating the belt tension at various points on the drum based on the force acting on the drum, and by designing and positioning reinforcing ribs to enhance the drum’s strength.
(3) Improve the welding process to ensure weld quality. The weld between the plate and the cylinder is a critical step in drum manufacturing. According to design requirements, weld quality must meet the JB1152-81 Class II standard.
A welding method employs gas-shielded welding with a mixture of CO2 and Ar for root pass welding, followed by automatic submerged-arc welding. During welding, the drum is mounted on a roller frame and rotated at a controllable speed. For the root pass, the torch must be operated manually, using single-sided welding with double bead formation to ensure that the weld root penetrates without defects such as cracking. For subsequent weld passes, welding can be performed by mounting the arc-welding machine head or the torch horizontally above the drum weld, enabling automation through drum rotation. Post-weld tempering is required. Since the drum shaft has already undergone quenching and tempering, tempering the entire drum would degrade the shaft’s performance; therefore, only localized tempering of the weld joint is permitted. A rail-type far-infrared heater is used to temper the weld and relieve residual welding stresses. The heater is wrapped around the weld and covered with insulating cotton.
(4) Strengthen maintenance to extend the drum’s service life, such as keeping the work area clean and ensuring adequate heat dissipation; do not allow the belt to slip along the drum; tighten immediately if looseness is detected; ensure that the cleaning equipment functions properly and prevent debris from adhering to the drum surface.
(5) Regular maintenance to ensure reliable operation.
(6) Apply rubber to the drum surface, using polyurethane or other wear-resistant materials as a coating, thereby increasing friction between the drum and the belt, reducing wear, preventing cracks, and extending the drum’s service life.
Practical experience has demonstrated that the improvement measures implemented to address drum failure in belt conveyors are viable, reasonable, reliable, and practical. The drum is a critical component of the belt conveyor. Starting with an analysis of the forces acting on the drum, enhancing manufacturing quality—particularly weld quality—and ensuring proper operation and maintenance are essential to ensuring the drum’s performance and longevity.

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