Monitoring Technology Of Fluid Magnetic Abrasive Hole Finishing Based On Acoustic Emission

As a kind of common machining characteristic, holes widely exist in themany mechanical parts, such as biological, medical apparatus, vehicles,aerospace s equipment and other fields equipment. Holes surface quality has animportant influence on the quality of whole product. With the development ofhigh flow velocity, high precision equipment, it put forward higher requirementson the surface quality of the hole. However, all the current internationaltechnologies can t solve the micro hole, profiled hole and pipe finishing problem.Therefore, based on long-term studies in the Fluid Magnetic Abrasive (FMA)finishing, Taiyuan University of Technology professor Sun Huanwu researchteam using special magneto rheological properties of the FMA, put it used in thefinishing field of complex cavity,hole parts, tubes, etc.This topic is derived from Graduate student innovation project in ShanxiProvince department of education （S20143052）,the open project of precisionand nontraditional machining technology of Ministry Education Key Laboratory(JMTZ201603）the national natural science foundation of China (51075294) andthe natural sciencefoundation of Shanxi Province (2010011034.1). The shear stress distribution of FMA in the pore, the calculation of material removal rate,finishing mechanism, finishing equipment, acoustic emission monitoring systemand acoustic emission signal processing are systematically studied in this paper.And some analyses were done from the theoretical analysis and experimentalverification two aspects. Main research contents are as the following:1) Study on the finishing mechanism of FMA hole finishing. Based ondipole moment of magnetic particles, the mechanism of FMA magnetorheological phenomenon was analyzed；the “double radius” model was used asthe model of the abrasive particles grinding. Based on the mechanical analysisof single grain, mathematical expressions of the hole finishing material removalrate was deduced; Then the material removal methods of the FMA hole finishingwas analyzed.Through experiment this paper studied some main factorsaffecting on hole finishing effect, such as magnetic field strength, inlet pressureof specimens, particle size and the specimen material. Then analyzed theexperimental results through the theoretical formula, and proved the correctnessof the theoretical derivation.2) Design and optimize the FMA hole finishing experimental device. In theguidance of materials removal mechanism of FMA hole finishing, a set ofexperimental device was designed which is excellent abrasion resistance andconstant pressure based on the existing equipment.3) Based on the acoustic emission (AE) monitoring principle andcharacteristics, analyzed acoustic emission source types and acoustic emission signal spectrum of FMA hole finishing process. The acoustic emission sensortype and arrangementhas been determined. Through collecting AE signal in twodifferent operating conditions which are FMA finishing device idle and working,found that the background noise and processing the signal is very small, can beneglected.4) Based on the characteristics of FMA hole finishing process, found thecharacteristic parameter analysis method is suitable for this experiment. Severalcharacteristic parameters are been calculated, and found the effective value ofAE signals can reflect the FMA hole finishing machining process.5) Analysis the impacts of magnetic field strength, inlet pressure ofspecimens, particle size and specimen material on the signal effective value andfrequency of AE signal, and get conclusion that the AE signal band of FMA holefinishing is in30KHz~500KHz.Get the relationship between Ra of workpieceand RMS value of AE signal.This paper studied the processing mechanism of the FMA hole finishing,and deduced the material removal model, designed the hole finishing processingequipment, set the AE on-line monitoring platform, determined the AE signalfrequency of FMA holes finishing. And through the experiment, verified thevalidity of the calculation of the processing mechanism and material removalrate, from experiment testing and acoustic emission monitoring two aspects.Research result has a certain reference value for the small hole finishing andother finishing forms online test.