Research On Reliability Of Mine Hoist Spindle System Under Multi-failure Mode

Mine hoist is widely used in mineral resources mining industry because of its excellent lifting capacity,and as the central mechanical equipment in the mining field,it plays the role of upgrading mineral,transporting personnel and mining accessories.The mine hoist with high reliability and stability is a powerful guarantee for efficient mining operation and safety of workers.Therefore,the reliability level of mine hoist has always been highly valued by mining enterprises.The traditional concept of hoist reliability research based on static strength theory can not reflect the real loading state and dynamic reliability trend of the spindle system,so it is difficult to accurately estimate the hoist service life.Therefore,a modern design method that can accurately characterize the overall load law of the spindle system and its reliability model during hoist operation is an urgent task for mining machinery research and development department,which is also conducive to the design and manufacture the mine hoist with high reliability.Mine hoist spindle system has been affected by unstable alternating stress for a long time.Damage will gradually accumulate and expand in each part,and various physical properties of materials such as initial strength also tend to degenerate gradually.There are many failure modes for parts because of complex loading state and bad working environment.Considering that the movement and force transfer for each part in the spindle system are mutually influencing,there is a certain degree of failure correlation between different failure modes of the same part and different parts in the spindle system.In view of the shortcomings of the traditional concept of hoist reliability research,this paper studies the reliability of mine hoist spindle system and its components under multi-failure mode from the perspectives of strength degradation and failure correlation.The main points are as follows:(1)A strength degradation model based on P-S-N curve is established.When describing the strength degradation process,it is usually difficult to obtain the degradation data directly,which is a typical lack of test data.In this paper,Gamma process is used to describe the strength degradation law of each part in the main shaft system of mine hoist,and the shape and scale parameters of the model are estimated by means of fatigue test data and P-S-N curve.Finally,the strength degradation model based on P-S-N curve is obtained.(2)The real-time stress state of key parts in spindle system is analyzed by periodic cycle method,and the reliability model of each part in each failure mode is established by combining with failure probability function.Considering that in the process of hoist operation,with the lifting and dropping of heavy objects and the continuous winding of wire rope,the stress state of each part is more complex,so this paper simulates the stress change diagram of each part under different working conditions,and incorporates it into the established reliability model.Using Monte Carlo sampling method to sample every parameter randomly in the model,and the dynamic reliability curves of each part under each failure mode are obtained.(3)The correlation among failure modes in spindle system is analyzed.Firstly,the correlation among failure modes in a single part is described by using two-dimensional hybrid Copula function,and the failure correlation model at the part level is completed.Then,a fourdimensional hybrid Copula function model is established to describe the failure correlation among parts in spindle system.Finally,the dynamic reliability curve of the whole spindle system under failure-related conditions is obtained.(4)In order to verify the rationality of the used methods in this paper,the reliability of spindle system under three different conditions is compared and verified by combining the theory of mutual independence hypothesis and the theory of complete correlation hypothesis.The conclusion shows that the reliability evaluation of spindle system based on complete correlation hypothesis theory is on the high side;the reliability evaluation of spindle system based on mutual independence hypothesis theory is on the low side;The reliability values based on the mixed Copula function theory in this paper are between the theoretical values of independent hypothesis and the theoretical values of complete correlation hypothesis,which is consistent with the engineering practice.