The tensioning device of a continuous casting roller table is a key component that ensures the synchronization of the transmission system. Its failure can directly disrupt the stability of the roller table's operation, further impacting the accuracy and efficiency of billet conveying. The tensioning device adjusts the tension of transmission components (such as chains and belts) to ensure consistent linear speeds among roller units under high-speed, high-temperature, and heavy-load conditions. If the tensioning device fails, fluctuations in transmission component tension can lead to speed differences between rollers, causing billet deviation, jamming, or even equipment downtime, seriously threatening the continuity of the continuous casting process.
If the tensioning device fails, insufficient or uneven tension in the transmission components can directly degrade the synchronization of the continuous casting roller table. For example, in chain transmissions, under normal operating conditions, the tensioning pulley maintains chain preload through a spring or hydraulic system, ensuring uniform force across all links. If the tensioning device fails, chain slack can cause poor engagement of the links and generate impact loads. This impact is transmitted through the sprocket to adjacent rollers, causing speed fluctuations. For example, when a roller chain jumps a tooth due to insufficient tension, its speed temporarily decreases, causing adjacent rollers to accelerate due to the sudden load change, resulting in a speed difference. This speed difference accumulates during the strand conveying process, ultimately causing the strand to deviate.
A loss of synchronization can also increase the dynamic loads on the continuous casting roller table. When the tensioning device fails, the vibration frequency and amplitude of the transmission components significantly increase. For example, in a belt drive, insufficient tension can cause periodic slippage between the belt and pulley, generating high-frequency vibration. This vibration is transmitted to the roller frame through the roller bearings, causing resonance in the entire structure. Long-term vibration can lead to failures such as fatigue cracking of the roller bracket and fracture of the bearing cage. For example, a steel plant's continuous casting roller table experienced increased vibration in the belt drive system due to a failed tensioning device. This resulted in multiple bearing failures within three months, significantly increasing repair costs.
Tensioning device failure also impacts the synchronization of the continuous casting roller table by reducing its ability to compensate for thermal deformation. During the continuous casting process, roller tables must operate continuously in high-temperature environments, causing transmission components to experience length changes due to thermal expansion. Tensioners use elastic elements (such as springs) to absorb thermal deformation and maintain stable tension in transmission components. If the tensioner fails, thermal expansion can cause excessive slack in the chain or belt, preventing self-regulation to restore tension. For example, in the secondary cooling zone, the billet temperature can reach over 1000°C, leading to significant thermal expansion of the roller components. If the tensioner cannot compensate for thermal deformation, chain slack can cause tooth skipping, disrupting billet transport.
Furthermore, a failure in the tensioner can reduce the mechanical components' ability to adapt to sudden load changes. During the continuous casting process, billet weight, size, and operating speed can fluctuate frequently, requiring the transmission system to respond quickly. The tensioner ensures stable transmission components by adjusting tension in real time. If the tensioner fails, sudden load changes can cause the chain or belt to slip, resulting in speed fluctuations. For example, if the tensioning device fails to increase tension in time when the strand moves from a light-load zone to a heavy-load zone, the chain can break due to overload, causing the roller table to shut down.
Tensioning device failure also impacts the maintenance cycle and cost of the continuous casting roller table. Under normal circumstances, the tensioning device's automatic adjustment function extends the service life of transmission components. However, if the tensioning device fails, transmission components will require frequent replacement due to abnormal wear. For example, a steel plant's continuous casting roller table suffered a tensioning device failure, which reduced the chain life from two years to six months, increasing annual maintenance costs. Furthermore, the loss of synchronization caused by tensioning device failure accelerates the damage of key components such as roller table bearings and gears, creating a vicious cycle.
To ensure the transmission synchronization of the continuous casting roller table, the tensioning device must be optimized from three aspects: design, maintenance, and monitoring. During the design phase, high-reliability tensioning components (such as hydraulic tensioners) should be selected, and redundant designs should be implemented to mitigate single-point failures. During maintenance, parameters such as the tensioning device's spring stiffness and hydraulic system pressure should be regularly checked to ensure they are within the normal operating range. During the monitoring phase, vibration sensors, tension detectors, and other equipment can be introduced to provide real-time feedback on the tensioning status and implement preventive maintenance. These measures can effectively reduce the risk of tensioning device failure and improve the operating stability and production efficiency of the continuous casting roller table.
