Fatigue Life Analysis For Four-high Reversible Rolling-mill Housing

Rolled mill stand is one of the most important components of rolled mill, which is used to install roller system and roller adjustment device. And it bears the rolling force, its strength and deformation will affect the reliability of the equipment, rolling precision of products and the assembly relationship between equipments. Therefore mill stand should have sufficient intensity and rigidity to ensure the reliability of its work. Then,just for mill stand's maintenance,the service life and the design level, it's important to analyze its intensity and rigidity and study its fatigue life.A reversible four-high rolling mill of 1700 Production Line is studied in this paper, and the finite element method is adopted to analyze the stress and deformation of rolled mill stand; The rolling mill load spectrogram is counted according to the scene roll force test .With the finite element computed result, the revised Miner principle and the Cotren-Dolan misalignment defect theory, as well as the revised p-S-N curve are used to carry on the weary reliability design and the fatigue life analysis computation to the rolled mill stand.The paper first uses the finite element method to analyze the whole rolled mill stand. The computed result indicates: the biggest stress lies on the nut hole crown transition arc in the rolled mill stand. Because stress gradient on this spot is big and the transition arc radius is very small, the sub-model method must be adopted to carry on the precise computation; the side force exerted to the rack column by the bearing seat of roller has the very tremendous influence to the housing window horizontal direction distortion, which must be taken into account in order to calculate the housing window distortion precisely.The paper second uses sub-model method and smaller-sized units to carry on the refinement analysis and the structure optimization to the biggest stress spot—the nut hole crown transition arc in the rolled mill stand, which enhances the computation efficiency and precision and makes partial modification to the structure.In the paper , the stress spectrogram is established according to the statistics of the scene roll force test and the finite element computed result, the revised Miner principle and the Cotren-Dolan misalignment defect theory, as well as the revised p-S-N curve are used to carry on the weary reliability design and the fatigue life analysis computation to the rolled mill stand.The structure analysis and the random fatigue life analysis computation used in this paper are suitable not only for the rolling-mill housing, but also for the general large-scale metal structure and the equipment part.