In continuous casting production, the continuous casting roller table plays a crucial role in supporting and transporting high-temperature cast billets. Its design directly impacts the surface and internal quality of the billet, particularly the control of crack defects. Crack formation is typically closely related to thermal stress, mechanical stress, material properties, and process parameters. Therefore, optimization is needed from multiple dimensions, including roller table structure, material selection, cooling system, and process adaptability, to reduce crack risk.
The roller structure of the continuous casting roller table is central to crack control. Traditional rollers often suffer from insufficient rigidity or poor arc alignment, leading to bulging deformation of the billet during transport and subsequently internal cracks. Optimization methods include adopting segmented roller designs, reducing bending stiffness by decreasing the length of individual roller sections and improving arc alignment accuracy; simultaneously, depositing a high-hardness, thermally crack-resistant alloy layer on the roller surface enhances wear resistance and thermal fatigue resistance. Furthermore, the roller spacing needs to be precisely adjusted according to the billet thickness and steel grade characteristics to avoid billet instability due to excessive spacing or increased mechanical stress due to insufficient spacing. The uniformity of the cooling system is crucial for controlling the temperature gradient of the cast billet. Uneven cooling leads to inconsistent shrinkage between the surface and interior of the billet, resulting in thermal stress cracks. The cooling water channel design of the roller table needs to be optimized into a spiral or annular water trough to ensure uniform coverage of the roller surface and avoid localized overheating. Simultaneously, an intelligent temperature control system should be employed to adjust the cooling water flow rate in real time according to the billet temperature, preventing cracks caused by sudden changes in cooling rate. For example, appropriately reducing the cooling intensity in the solidification end region can reduce the risk of central cracks.
Material selection directly affects the crack resistance of the roller table. Under high-temperature conditions, the roller material must possess high strength, good thermal conductivity, and resistance to thermal fatigue. Traditional materials such as low-carbon steel are prone to surface cracking due to thermal stress, while high-chromium alloy steel or composite materials (such as ceramic-reinforced metal matrix composites) can significantly improve roller life. Furthermore, roller surface treatment processes (such as laser cladding and plasma spraying) can form a dense, crack-resistant layer, further preventing thermal erosion of the rollers by the high-temperature cast billet. The compatibility of the roller table with the continuous casting process is another key factor in crack control. Different steel grades (such as high-carbon steel and alloy steel) have significantly different solidification characteristics, requiring targeted adjustments to roller table parameters. For example, high-carbon steel, due to its wide brittle temperature range, necessitates strict control of the roller angle and cooling intensity in the straightening zone to avoid straightening in the brittle region. Conversely, thin slab continuous casting, with its rapid cooling rate, requires optimized roller arrangement density to reduce bulging. Furthermore, dynamic light-pressure technology can apply controllable pressure to the slab through the rollers, compensating for solidification shrinkage and reducing center segregation and cracks.
A robust online monitoring and maintenance system is fundamental to ensuring the long-term stable operation of the roller table. By installing vibration sensors, temperature sensors, and infrared thermal imaging equipment, the roller status can be monitored in real time, allowing for early detection of potential problems such as wear, arc deviation, or abnormal cooling. Combined with data analysis models, roller life can be predicted, and preventative maintenance plans can be developed to avoid slab cracks caused by roller table failures. For example, regularly inspecting the surface roughness of the rollers and promptly repairing or replacing worn rollers can prevent scratches on the casting billet due to roller surface defects.
The coordinated optimization of the roller table with upstream and downstream equipment is equally important. Parameters such as crystallizer vibration, secondary cooling spray, and billet drawing speed need to be matched with the roller table design to form a closed-loop control. For example, excessively high crystallizer vibration frequency may lead to a weak initial shell on the billet surface, increasing the risk of cracks during subsequent roller table transport; while improper secondary cooling spray angle may cause localized overcooling of the billet, triggering thermal stress cracks. Therefore, it is necessary to determine the optimal process window through simulation and field testing.
Through comprehensive measures such as roller structure optimization, cooling system improvement, material upgrades, process adaptation, online monitoring, and equipment coordination, the continuous casting roller table for steel machinery components can significantly reduce billet crack defects. These optimizations not only improve product quality but also reduce production costs, providing a strong guarantee for the efficient and stable operation of continuous casting production. In the future, with the development of intelligent manufacturing technology, roller table design will further evolve towards intelligence and refinement, achieving zero-tolerance control of crack defects.
