Research On Remaining Useful Life Prediction Method Of Elevator Block Brake

Block brake is the key equipment to ensure the safe operation of passenger elevator,in long-term working use,the braking performance of block brake will gradually deteriorate,forming potential safety hazards,serious cases will cause casualties.It is necessary to carry out research on failure prediction and remaining life evaluation.In order to prevent elevator accidents and better protect the life safety of elevator passengers,this paper takes DZD1-500 block brake as the research object,analyzes the influencing factors of braking torque performance degradation,and carries out the remaining life prediction research of block brake.The main research work of the thesis is as follows:Firstly,according to the structure and working principle of the block brake,the failure mode of the block brake is analyzed by the fault tree method,the correlation between different failure modes and performance indicators of the block brake is established,and the braking torque is confirmed as the most important performance index of the block brake,so the brake torque is used as the life index.The formation mechanism of braking torque is analyzed,and it is pointed out that the main reason for insufficient braking torque is the degradation of braking pressure,and the reason for the degradation of braking pressure is the wear of brake tile and the decrease of brake spring rate coefficient.Secondly,according to the law of spring stress relaxation rule,the degradation law of spring stiffness coefficient is derived,and the main wear mechanism of the brake tile is abrasive wear according to the surface morphology analysis of the friction surface of the brake tile.Considering the interaction between the wear amount of the brake tile and the braking pressure during long-term operation,the degradation law of the spring rate coefficient is combined with the Archard wear model,and the differential equation describing the overall wear of the brake tile and the working time of the block brake is derived.Then,design tests collect data on brake pad wear and brake spring rate coefficient degradation.The distribution test of degradation data demonstrates the rationality of using the Gamma process to describe the degradation process of brake pad wear and brake spring rate coefficient.The braking torque bench test is designed,and the equivalent test method is adopted to change the braking pressure by changing the free stroke of the brake spring,and the braking torque data corresponding to different braking pressures are obtained.The relationship between braking torque and braking pressure is fitted to obtain a model describing the relationship between braking torque and braking pressure.Finally,the failure threshold of braking torque is calculated according to the parameters of a certain model of elevator and relevant national standards.According to the working principle of block brake and the relationship between braking torque and braking pressure,a composite degradation model of braking torque composed of two Gamma processes is established.By constructing intermediate variables,the composite degradation model is transformed into a variable failure threshold degradation model for the wear of the brake tile,and the reliability calculation method is derived.The maximum likelihood estimation method is used to calculate the relevant parameters of the model,the relationship between reliability and service time is calculated,and the predicted value of block brake life is obtained according to the reliability curve.