Study On Fatigue Life Of Roller Sleeve Of Cast Roll

To produce aluminum strips adopting the technology of continuous roll casting is such kind of near-net forming the chnology that can combine the solidifying and deforming. The twin roll continuous casting of aluminum was developed into a commercial process by Hunter-Danglas company in the early 1950’s,since then,the process has gained world-wide acceptance in the aluminum industry,because it has littler investment,highter production and lower power consumption etc.Recently,The process has gained rapid development,it became the major method to produce aluminum strips.Today, it has produced kinds of thin steel strips and complex materials strips by using this process. International industry aluminum processing considers that the technology of high speed thin gauge twin roll casting represents a essential aspect of aluminum processing of a new generation and commanding point of aluminum processing technics;and international iron and steel processing industry takes the technology as a important research area.The roller is very important in continuous roll casting process in the roll casting machine.It is constitute of the roll core and roll shell,the roller acts as the crystallize machine and also acts as process tool in the casting process.The heat that the melted aluminum gives out in the course of cooling and solidification is mostly transferred to the roll shell,and it is absorbed and taken out of by the cooling water, as a result,the roll shell is impacted by the periodic thermal load ,it also undertake great rolling force.Under the compositive effects of thermal stress,rolling stress and assembling stress,the roll shell liable produces mechanical and thermal fatigue.As a result,it induces the roll shell’s invalidation.Most of the roll shells produce fatigue cracks and result its invalidation ahead of schedule.the roll shell is very expensive.When the roll shell is invalidation,it should Affect product quality and disrupt production ,so the research of the roll shell’s fatigue life has important significane.It can provide valuable reference to improve the quality of casting products and productivity, reduce production costs. Thermal fatigue crack is the major factor which leads the roll shell to failure,so the research of the roll shell’s fatigue life is to study the roll shell’s thermal crack initiating and crack propagation.Based on the analysis of the roll shell’s lifetime at home and abroad,and through simulation getting the distribution rule of the roll shell’s thermal and stress fields, this paper analyse the fatigue failure mechanism of roll shell of continuous roll casting.The two stages crack initiating and crack propagation were closely associated with each other to consider by using the theory of continuum damage mechanics,under the given stress field, the damage field was analysed and the crack expansion life was estimated by using Finite Element Method , and the concrete analysis steps were given out. Finally the feasibility of the method was validated through practical example. The research method changed the status that crack generation and crack expansion were analysed respectively, and built an entire and unitive analysis procedure. As the result shown,the fatigue life of roll shell is related to thermal fatigue of material of roll shell, heat conduction, thermal expansion coefficient and machining quality of surface directly, and provides important and valuable reference for improving service life of roll shell.