Optimal Placement Of Excitations And Sensors For CNC Machine Tools

Experimental modal analysis is an effective way to study the dynamic characteristicsof CNC machine tools, which is more and more important to the design and analysis ofhigh-end CNC machine tools. However, placement of response points in the modalexperiment for some large-scale structures depends on experience, and therefore leads tolow experimental efficiency and high cost. On the other hand, selection of excitations asone of the key links for experimental modal analysis is directly related to the effectivenessof excitations and the quality of the response data. Excitations are often selected accordingto experience and repeated experiments, which also leads to low efficiency andexperimental results depending on experience. So the research of.placement of responsepoints and selection of excitations is significant to improve the efficiency and reduce thecost. The main research work is as follows:The method to select excitations is studied and the corresponding rules are analyzed.The excitations is selected first by finite element analysis and is optimized by effectiveindependence method (EfI) or effective independent the driving point residue (EfI-DPR).Further the final excitations are acquired according to the selection rules summarized bythe engineering experience.Secondly, it’s studied that minimizing number of measuring points and optimizationof placement of measuring response under the condition that make sure that modal shapesof the structure can be identified accurately. All measuring points on surface werecollected in finite element model, and screened iteratively with the effective independencemethod based on contribution of data of points to modal response. At the same time,modal assurance criterion (MAC) was computed to evaluating the optimization, whichdetermines the number of response points with the economy of the test. To meet therequirements of accurate identification of modal shapes, measuring points was added todifferent structure by Shannon theorem.Doing the comprehensive experimental verification on the incentive point selectionand response point placement optimization in the XHK5140machine tools, and comparedwith the traditional method. The result of experiment showed that the method in accordwith traditional method, but the method has efficient and not depend on experience.Response point efficiently decreased from220to26with this method in the same effectAt last, we applied the method for the structure modal analysis of motion component of machine tools in different space position. The result showed that with the change ofmotion component position machine inherent frequency is changing, thinking thatstructure modal analysis of machine tools is changing with the change of motioncomponent position, and conclusion needs to be further more in-depth research.