Stress Analysis And Fatigue Life Of Backup Roll With Sleeve In Hot Rolling

Large rolling mill is the key technology equipment for modern metallurgic plant, andthe backup roll is the core components of the mill. With the development of modern hotstrip mill to large-scale, high-speed and automated direction, corresponding the demandfor hot roll backup become higher and higher, it was not only required the resistance tobend and not break,but also to have good wear resisting property. However, to meet thesetwo requirements simultaneously are very difficult or costly, backup roll with sleevessolve the problem of roll wear and fracture resistance.A large backup roll with sleeves was studied in this paper, describing the structureand material selection of backup roll; giving the calculation method of shrink range andassembly stresses between the roll sleeves and roll core; analyzing the contact problem inthe process of rolling using Hertz elastic contact theory; and analyzing the micro-slipphenomenon between rollers using some of the micro-tribology knowledge.The backup roll and work roll model was built and simulated using the finite elementanalysis software Abaqus. First, the temperature field simulation model of backup roll hasbeen developed and the temperature field was studied and the temperature fielddistribution of roll sleeve has been obtained after thermal balance. Second, the stress-strainfield of backup roll with different roll-sleeve thickness and different magnitude ofinterference were compared, and summarized the influence law of the two parameters tobackup roll with sleeves.Combined with metal fatigue theory and component fretting fatigue theory, thereasons of backup roll fatigue were analyzed and fatigue life of roll sleeves were estimated,and micro-slip was introduced to discuss as an important parameter causing sleevedbackup roll failure. Introduced the concept of stress relaxation, the phenomenon of stressrelaxation of shrink fit was simulated and the initial stress values change was obtained.According to the cumulative damage theory of fatigue, crack forming laws wereintroduced to make preparations for the roll life studies from the roll surface micro-cracksto extend the critical cracks. Three-dimensional model of backup roll with sleeves was established, and simulatedcompressive stress distribution among sleeves of backup roll with sleeves, and exploredthe stress distribution along the axial of sleeve, making up for the lack of two-dimensionalmodel.