Modeling And Diagnosis Of Hybrid Fault Propagation In NC Lathe

As a complex machine,electric and hydraulic integrated system,CNC machine tools,its component unit manufacturing process,design and other factors lead to its own defects and system operating environment,functional and mechanical high coupling strength and large density connection between component units.It provides the possibility of fault propagation and increases the difficulty and complexity of fault diagnosis.The system fault is the result of the discrete fault propagation of the structural association unit and the continuous fault propagation of the functional association unit,that is,the hybrid fault propagation.Equipment fault diagnosis is the basis of health maintenance,and it is one of the key intelligent basic technologies of equipment.Therefore,combined with the fault propagation characteristics of CNC machine tools for system fault propagation modeling and fault diagnosis is of great significance for rationally locating fault sources and fault propagation paths,and then troubleshooting.CNC lathes are typical CNC machine tools.The paper relies on the Jilin Province Natural Science Fund Project and the Jilin Province Science and Technology Development Plan Project,taking CNC lathe as the research object,applying graph theory to show the system unit fault propagation relationship,using fault injection and signal acquisition analysis to obtain fault propagation information,and introducing energy operator.And comprehensive fault transfer model feature calculation unit fault propagation probability,applying information entropy correlation theory,based on fault propagation intensity to evaluate fault propagation probability,to determine key fault nodes and fault propagation paths,combined with actual field data,based on Pagerank and fault propagation influence degree Verify the rationality of the hybrid fault propagation model and the effectiveness of the fault diagnosis.Firstly,combined with the working principle and fault type of CNC machine tools,the division of CNC lathe subsystem based on fault type is carried out.Based on the analysis of the working process and motion characteristics of the CNC lathe,the concept of continuous fault propagation of CNC lathe based on function is proposed.The concept of discrete fault propagation is defined for the fault propagation characteristics and propagation level relationship analysis of fault propagation related subsystems.Based on the comprehensiveity of fault propagation of CNC machine tools,a hybrid lagging fault propagation model for integrated continuous fault propagation and discrete fault propagation is established.Then,the fault injection method is introduced,and the fault propagation path and the key nodes in the motion coupling are functionally tested.The components with the transfer relationship are selected as the test objects from the functional components,and different processing conditions are applied.System component operation information is collected,signal processing and test data calculation,energy operator is used to evaluate energy transfer efficiency,and continuous fault propagation probability is evaluated.Based on correlation fault analysis,DEMATEL and ISM methods are used to introduce matrix theory to establish discrete fault propagation.The hierarchical structure model,combined with the edge-intermediate calculation of the edge load strength,evaluates the probability of discrete fault propagation.Finally,the Entropy theory is applied to calculate the intensity of the directed edge propagation.Based on this,the hybrid fault propagation model is used to construct the weighted hybrid fault propagation model.The fault propagation path and the critical fault node are determined based on the fault propagation strength and the node average failure rate to realize fault diagnosis.Combined with the actual production,the Pagerank method is used to calculate the influence of propagation to verify the application of the diagnostic strategy.