Online Identification Method Of Sliding Electric Contact Structure Damage Under Extreme Conditions

Sliding electrical contact is a very important component in industrial automation equipment.The quality of electrical contact will directly affect the safe operation of industrial equipment and the efficiency of industrial production.At present,the evaluation of electrical contact quality is mainly based on the health monitoring of the surface damage of electric contact rail.The surface damage of the sliding electric contact track is mainly caused by the wear,planing and ablation of the slider and the track.Because of the extreme conditions(multi field coupling interference and sliding speeds up to km/s,the number of pulse current up to tens of kA),there is not a perfect on-line identification scheme for the minor damage of sliding rail.In this paper,a high speed sliding electric contact test machine,which can simulate the extreme working environment of sliding rail,has been developed,and the on-line identification method of transient micro damage on the surface of sliding rail is carried out in this paper.In order to realize the on-line identification of the rail surface damage,this paper,on the basis of summarizing the structural health diagnosis methods at home and abroad,has studied and analyzed the shortcomings of the traditional structural dynamic characteristics that can not effectively identify the tiny damage of the structure,and proposes an improved method of on-line damage identification on the sliding surface based on the dynamic characteristics of the slide rails.First,the wavelet packet analysis method,which can identify the local characteristics of the sliding rail vibration signal,is used to decompose the signal with two layers of wavelet packet.Then,the instantaneous amplitude and the instantaneous frequency of the signal are solved by using the HHT method which has high response to the small signal.The instantaneous amplitude of the vibration signals of each measurement point is obtained.The instantaneous frequency is "abrupt" in the time domain to complete the online identification and location of the surface damage of the slide rail.Because the sliding rail is in the interior of the sliding electric contact structure and the strong electromagnetic impact caused by the high current of the pulse,the acquisition of the vibration signal of the slide rail has been greatly restricted.In order to accurately extract the instantaneous vibration signal on the sliding surface,this paper uses a piezoelectric acceleration sensor with anti strong electromagnetic interference to collect the vibration signal of the slide rail.Based on the finite element method,the vibration characteristics of sliding rail under the action of the external pretightening force are studied and analyzed.According to the simulation results,the hydraulic preload can significantly improve the accuracy of extracting the transient vibration signals of slideway.On the basis of this method,the sliding rail damage on-line identification system is used for many experiments,and the changes of the transient vibration signals of the sliding rail after the first experiment and several experiments are compared,and the actual pictures of the sliding rail surface before and after the experiment are compared.The experimental results are in agreement with the theoretical analysis.The research results can provide references for online identification of structural damage in other complex environments.