Research On Dynamic Friction Loading Mechanism And Accuracy Test Based On Elevator Load Test

As a necessary means of transport for high-rise buildings,elevators are closely related to People's Daily life and work.Special equipment inspection and testing institutions regularly carry out load tests on a large number of elevators,but the application of load is often achieved by carrying standard weights,which is time consuming and inefficient.Therefore,the electromagnetic friction combined load replacement technology for elevator load test is proposed.Dynamic friction loading is the key to ensure the accuracy and stability of the loading.In this paper,pneumatic disc brakes are used as dynamic friction loading tools to study the mechanism and accuracy of dynamic friction loading.Firstly,the status and development trend of dynamic loading and dynamic friction loading at home and abroad were comprehensively analyzed.By comparing and analyzing the existing dynamic loading methods and technologies,pneumatic dynamic friction loading was adopted as the main load method of electromagnetic friction combination.Through the analysis of contact conditions,dynamics and thermodynamics in the process of pneumatic dynamic friction loading,the friction mathematical model of pneumatic disc brake dynamic friction loading was established,including dynamic friction dynamics equation and dynamic friction thermodynamics equation.Based on Abaqus software,the dynamic friction loading process was simulated,and the temperature field distribution of friction parts was simulated and analyzed.The temperature change of friction surface was obtained.Secondly,the status of dynamic friction loading control methods at home and abroad was comprehensively analyzed.The method of using electric proportional valve to control air pressure for dynamic friction loading was determined.By analyzing the compressibility,viscosity and flow capacity of the input gas under dynamic friction loading,the pneumatic control circuit of pneumatic disc brake was designed and its pressure response mathematical model was established,including gas state equation,gas motion equation,gas continuity equation and energy equation.Through discrete processing of its mathematical model,the response characteristics of air pressure in the pneumatic control loop were simulated and analyzed.The results show that the pressure response time is about 0.4s in the pressure control loop with a length of 10 m and a pipe diameter of 8mm,and the rapidity is good.Then,starting from mechanical device,pneumatic control circuit and measurement and control system,the dynamic friction loading performance test platform was designed and built,and each part was debugged separately.The working performance of each device and component was tested.It shows that the designed test platform works reliably and stably.Finally,with the help of dynamic friction loading performance test platform,experimental studies were carried out on the control performance of friction plate positive pressure,the stability of friction torque loading under constant air pressure and the fixed point control performance of dynamic friction torque loading.The results show that the starting pressure of the pneumatic disc brake is between 0.04 MPa and 0.06 MPa.There is a linear relationship between the positive pressure and the square of the input pressure.The friction torque increases with the increase of friction temperature,and the faster the temperature of the friction component increases,the faster the friction torque value increases.The stability of friction torque loading under constant air pressure is poor,and it keeps increasing.The higher the input pressure is,the worse the stability of the friction torque is.The stability of dynamic friction load is improved obviously by using fixed point control method.The fixed point control error of the loading quantity is ?±50N·m,which meets the requirement of dynamic friction loading accuracy for electromagnetic friction combined load replacement technology.The research of this subject provides the theoretical and experimental basis for the research of dynamic friction loading technology,and it provides the theoretical and experimental basis for the research and development of elevator load test method and device.It has very important application value to improve the efficiency and accuracy of elevator load test.