Research On The Stochastic Wear Model Of Roller And Its Optimal Replacement Policy

Roll is an important tool in steel rolling process and the main consumable part. Its surface wear caused by periodically contacts with the workpiece and failure or malfunction caused by the wear are the main factors affecting the yield and quality of rolled products. Therefore, The research on roller's optimal replacement strategy which is based on the actual wear state of roller has a extremely important significance on continuous production process of rolling material and the improvement of corporate profits.Given roll high manufacturing costs and the purchase price, rolling mills usually adopt rollers' replacement periodically and use them again after grinding and it may lead to roller too early or too late to repair because this policy ignores the real operation condition of the roller. Based on the background of 1780 mm strip mill roller in the strip steel production system and the available roll grinding data, the paper studies roller's random wear characteristics and establishes dynamic wear reliability model from the viewpoint of probability theory and reliability theory, and then studies the optimal decision making problems of the regular replacement policy in order to determine roller system optimization change cycle, finally through the instance analysis to prove the feasibility and reliability of roller's optimal replacement policy research method. The main contents of this paper are as follows:(1) According to the existing work roll grinding cycle of the rolling mills,with the aid of mature roll wear quantity measurement technology, collect work roll precision grinding data in the actual operating conditions, and then the further research is done to explore the random deterioration characteristics of the work roller.(2) Based on roll wear mechanism, combined with the typical roll wear prediction model, and in accordance with the common random degradation modeling idea and method in mechanical engineering field, and the dynamic wear model of work roller is established to study stochastic wear properties of work roller.(3) On the basis of dynamic wear reliability model and then combined with the regular replacement cycle,the various costs generated in roll replacement maintenance process and demand for roller operation reliability, this paper establishes the optimal replacement model with average minimum replacement cost as the objective and with the optimal roll change cycle as the decision variables.