Research On Magnetic Flux Leakage Detection Technology Of Elevator Pulled Steel Strip

In recent years,In recent years,as a load-bearing component,elevator drawn steel belt has gradually replaced the traditional elevator drawn steel wire rope.However,when it runs in the environment of impact and heavy load for a long time,several steel wire ropes,which mainly bear the load,will appear broken wire,broken strand,wear and other damage.The structural integrity of elevator towed steel belt is directly related to the safety of elevator operation.At present,the damage evaluation method of elevator towed steel belt is extremely needed,so it is necessary to study the nondestructive testing of elevator towed steel belt.Aiming at the problem of non-destructive detection of elevator drag steel strip damage,the magnetic leakage detection technology of elevator drag steel strip is studied by using the magnetic leakage detection method.Firstly,the principle of magnetic leakage detection of elevator pulled steel strip is analyzed,and the analytical and numerical methods for calculating magnetic leakage are studied,and the finite element method based on Maxwell equation is selected as the method in this paper.According to the actual size of the elevator traction steel belt,the finite element simulation model of the elevator traction steel belt is established.According to the various types of damage caused by the elevator pulled steel belt in actual operation,a variety of defect models are established to simulate the possible damage of the internal steel wire rope.The following studies were carried out by finite element method:(1)Characteristics of leakage magnetic field of broken wire,broken strand and wear defects.(2)Influence of lift value on finite element simulation results.(3)The influence of the depth of broken strand defect on the finite element simulation results.(4)The influence of the width of broken strand defect on the finite element simulation results.(5)The influence of the depth of wear defects on the finite element simulation results.The relative methods of wavelet denoising are analyzed and studied.The denoising effects of different wavelet basis functions are evaluated by two parameters,signal-to-noise ratio(SNR)and root-mean-square error(RMSE),and then the wavelet basis function for magnetic leakage signal denoising of elevator traction steel strip is determined.According to the special operating environment of elevator traction steel belt,a prototype of magnetic leakage detection equipment for elevator traction steel belt is designed,which includes sensor part,control part and mechanical structure part.Sensor part: The appropriate magnetic sensor element is selected,and the sensor array is designed according to the size of the magnetic sensor element and the structural characteristics of the elevator pulled steel strip.The sensor array and the encoder realize the accurate positioning of defects.Control part:Based on BCM2835 and STM32,the embedded detection system is designed to realize the communication between the upper computer and the lower computer through wireless network,and to view the detected leakage magnetic field data in real time.Mechanical structure: According to the specific size of the elevator pulled steel belt,the magnetization structure and the rest of the structure of the detection equipment are designed.Several different defects were processed on a section of elevator traction steel belt,and the prototype of the elevator traction steel belt magnetic leakage detection equipment was used for experiments.The feasibility of magnetic flux leakage testing for non-destructive testing of elevator traction steel strip is analyzed and studied.Experiments show that magnetic flux leakage detection can effectively detect the broken wire,broken strand and wear damage of the steel wire rope inside the elevator pulled steel belt.