Large-scale Rotary Kiln Components Rolling Contact Fatigue Research

Rotary kiln is the key equipment in metallurgy, chemistry and architectural material. So the safety and efficiency of its operation is the crux to advance economic benefit of such enterprises. Kiln's supporting part, tyres and rollers, are working in the style of rolling contact. And maintenance recording shows that they both often fail at the time when it is much shorter than their expecting life. On worse, the sudden fails of them can be a great threaten to workers' lives on the operating bridge, and what's more, it will cause the break of the production process, hence great productivity losses.To the problem, in the paper, fatigue life of a kiln tyre has been re-evaluated. Based on the study to the mechanism of procession of the tyre-roll structure's rolling contact fatigue (RCF), a new engineering method has been proposed of calculating the fatigue life the rolling support parts. The new method has the traits of having definite physical procession, less middle steps and easier way of getting parameter, etc. Fatigue experiment has been carried out and conclusions about the stability and accuracy of the method have been achieved.Starting from the comprehensive analysis of the tyre's stress distribution with the FEM software, ANSYS, and the data of the tyre's temperature distribution, and through heat-force-couple analysis, the locations of the dangerous points and their various rule in a cycle. With Stress and Strain Analysis to the fatigue life of the certain tyre, the result shows that its fatigue life is about 3 years long.To direct at the prediction method of fatigue life of under the special working condition, an on-the-spot research was made and specimens for scanning electronmicroscopy were obtained at the spot of the fracture accident of the rolls in CHALCO Henan branch in June, 2004. Macroscopic fractography of the cracks as well as microscopic fractography of the specimens with SEM has been made and a new model of explanation about how the damage cumulates and how the crack evolves of the tyre-roll structure under rolling contact condition. Based on the model, and on reference of mature method of fatigue analysis, anew formula has been developed of predicting the fatigue life of the structures of rolling contact which based on recycling ratchet energy and no-liner damage theory.Through fatigue experiment with 4 group of specimens and over 10 thousand cycles, kiln tyre's fatigue parameter of the overall shearing ratchet energy was obtained. Based on the parameter, fatigue life have been calculated with the RCF life prediction formula.