Performance degradation or failure of manufacturing equipment will badly influence machining quality.Because of discontinuousness of the milling process,dynamic signals produced in the milling process become non-stati...Performance degradation or failure of manufacturing equipment will badly influence machining quality.Because of discontinuousness of the milling process,dynamic signals produced in the milling process become non-stationary.This paper indicates that the essence of SGW(second generation wavelet) transform in non-stationary signal processing is the mathematics principle of inner product transform of a dynamic signal with basis functions.Namely,by means of the inner product operation of a signal with basis functions containing scale function and wavelet function,signal decomposition and reconstruction are obtained.Acoustic emission signals generated in the milling processes of a CNC machine were analyzed by using the basis functions of SGW which are oscillation,decay and compact support.The features of end milling cutter breakage have been extracted,and the influences on machining surface quality have been identified effectively,which provide scientific bases for fault diagnosis,error tracing and quality control.展开更多
Titanium alloy has been applied in the field of aerospace manufacturing for its high specific strength and hardness.Nonetheless,these properties also cause general problems in the machining,such as processing ineffici...Titanium alloy has been applied in the field of aerospace manufacturing for its high specific strength and hardness.Nonetheless,these properties also cause general problems in the machining,such as processing inefficiency,serious wear,poor workpiece face quality,etc.Aiming at the above problems,this paper carried out a comparative experimental study on titanium alloy milling based on the CAMCand BEMC.The variation law of cutting force and wear morphology of the two tools were obtained,and the wear mechanism and the effect of wear on machining quality were analyzed.The conclusion is that in contrast with BEMC,under the action of cutting thickness thinning mechanism,the force of CAMC was less,and its fluctuation was more stable.The flank wear was uniform and near the cutting edge,and the wear rate was slower.In the early period,the wear mechanism of CAMC was mainly adhesion.Gradually,oxidative wear also occurred with milling.Furthermore,the surface residual height of CAMC was lower.There is no obvious peak and trough accompanied by fewer surface defects.展开更多
The surface quality of chamfer milling of stainless steel is closed related to the products of 3 C(Computer, Communication and Consumer electronics), where a cutter is a major part to achieve that. Targeting a high-qu...The surface quality of chamfer milling of stainless steel is closed related to the products of 3 C(Computer, Communication and Consumer electronics), where a cutter is a major part to achieve that. Targeting a high-quality cutter,an experimental evaluation is carried out on the influence of grinding texture of cutter flank face on surface quality.The mathematic models of chamfer cutter are established, and they are validated by a numerical simulation. Also the grinding data are generated by the models and tested by a grinding simulation for safety reasons. Then, a set of chamfer cutting tools are machined in a five-axis CNC grinding machine, and consist of five angles between the cutting edge and the grinding texture on the 1 st flank faces, i.e., 0°, 15°, 30°, 45° and 60°. Furthermore, the machined cutting tools are tested in a series of milling experiments of chamfer hole of stainless steel, where cutting forces and surface morphologies are measured and observed. The results show that the best state of both surface quality and cutting force is archived by the tool with 45° grinding texture, which can provide a support for manufacturing of cutting tool used in chamfer milling.展开更多
Ultrasonic cutting with a disc cutter is an advanced machining method for the high-quality processing of Nomex honeycomb core.The machining quality is influenced by ultrasonic cutting parameters,as well as tool orient...Ultrasonic cutting with a disc cutter is an advanced machining method for the high-quality processing of Nomex honeycomb core.The machining quality is influenced by ultrasonic cutting parameters,as well as tool orientations,which are determined by the multi-axis machining requirements and the angle control of the cutting system.However,in existing research,the effect of the disc cutter orientation on the machining quality has not been studied in depth,and practical guidance for the use of disc cutters is lacking.In this work,the inclined ultrasonic cutting process with a disc cutter was analyzed,and cutting experiments with different inclination angles were conducted.The theoretical residual height models of the honeycomb core,as a result of the lead and tilt angles,were established and verified with the results obtained by a linear laser displacement sensor.Research shows that the residual height of the honeycomb core,as a result of the tilt angle,is much larger than that as a result of the lead angle.Furthermore,the tearing of the cell wall on the machined surface was observed,and the effects of the ultrasonic vibration,lead angle,and tilt angle on the tear rate and tear length of the cell wall were studied.Experimental results revealed that ultrasonic vibration can effectively decrease the tearing of the cell wall and improve the machining quality.Changes in the tilt angle have less effect than changes in the lead angle on the tearing of the cell wall.The determination of inclination angles should consider the actual processing requirements for the residual height and the machining quality of the cell wall.This study investigates the influence of the inclination angles of a disc cutter on the machining quality of Nomex honeycomb core in ultrasonic cutting and provides guidelines for machining.展开更多
基金Supported by the National Nature Science Foundation of China (Grant No. 50335030)the National Basic Research Program of China ("973") (Grant No. 2005CB724100)
文摘Performance degradation or failure of manufacturing equipment will badly influence machining quality.Because of discontinuousness of the milling process,dynamic signals produced in the milling process become non-stationary.This paper indicates that the essence of SGW(second generation wavelet) transform in non-stationary signal processing is the mathematics principle of inner product transform of a dynamic signal with basis functions.Namely,by means of the inner product operation of a signal with basis functions containing scale function and wavelet function,signal decomposition and reconstruction are obtained.Acoustic emission signals generated in the milling processes of a CNC machine were analyzed by using the basis functions of SGW which are oscillation,decay and compact support.The features of end milling cutter breakage have been extracted,and the influences on machining surface quality have been identified effectively,which provide scientific bases for fault diagnosis,error tracing and quality control.
基金Supported by National Natural Science Foundation of China(Grant No.51975168).
文摘Titanium alloy has been applied in the field of aerospace manufacturing for its high specific strength and hardness.Nonetheless,these properties also cause general problems in the machining,such as processing inefficiency,serious wear,poor workpiece face quality,etc.Aiming at the above problems,this paper carried out a comparative experimental study on titanium alloy milling based on the CAMCand BEMC.The variation law of cutting force and wear morphology of the two tools were obtained,and the wear mechanism and the effect of wear on machining quality were analyzed.The conclusion is that in contrast with BEMC,under the action of cutting thickness thinning mechanism,the force of CAMC was less,and its fluctuation was more stable.The flank wear was uniform and near the cutting edge,and the wear rate was slower.In the early period,the wear mechanism of CAMC was mainly adhesion.Gradually,oxidative wear also occurred with milling.Furthermore,the surface residual height of CAMC was lower.There is no obvious peak and trough accompanied by fewer surface defects.
基金Supported by Heilongjiang Provincial Natural Science Foundation of China(Grant No.QC2016070)
文摘The surface quality of chamfer milling of stainless steel is closed related to the products of 3 C(Computer, Communication and Consumer electronics), where a cutter is a major part to achieve that. Targeting a high-quality cutter,an experimental evaluation is carried out on the influence of grinding texture of cutter flank face on surface quality.The mathematic models of chamfer cutter are established, and they are validated by a numerical simulation. Also the grinding data are generated by the models and tested by a grinding simulation for safety reasons. Then, a set of chamfer cutting tools are machined in a five-axis CNC grinding machine, and consist of five angles between the cutting edge and the grinding texture on the 1 st flank faces, i.e., 0°, 15°, 30°, 45° and 60°. Furthermore, the machined cutting tools are tested in a series of milling experiments of chamfer hole of stainless steel, where cutting forces and surface morphologies are measured and observed. The results show that the best state of both surface quality and cutting force is archived by the tool with 45° grinding texture, which can provide a support for manufacturing of cutting tool used in chamfer milling.
基金The authors are grateful to the financial support from the National Natural Science Foundation of China(Grant No.U20A20291)the National Key R&D Program of China(Grant No.2019YFA0708902).
文摘Ultrasonic cutting with a disc cutter is an advanced machining method for the high-quality processing of Nomex honeycomb core.The machining quality is influenced by ultrasonic cutting parameters,as well as tool orientations,which are determined by the multi-axis machining requirements and the angle control of the cutting system.However,in existing research,the effect of the disc cutter orientation on the machining quality has not been studied in depth,and practical guidance for the use of disc cutters is lacking.In this work,the inclined ultrasonic cutting process with a disc cutter was analyzed,and cutting experiments with different inclination angles were conducted.The theoretical residual height models of the honeycomb core,as a result of the lead and tilt angles,were established and verified with the results obtained by a linear laser displacement sensor.Research shows that the residual height of the honeycomb core,as a result of the tilt angle,is much larger than that as a result of the lead angle.Furthermore,the tearing of the cell wall on the machined surface was observed,and the effects of the ultrasonic vibration,lead angle,and tilt angle on the tear rate and tear length of the cell wall were studied.Experimental results revealed that ultrasonic vibration can effectively decrease the tearing of the cell wall and improve the machining quality.Changes in the tilt angle have less effect than changes in the lead angle on the tearing of the cell wall.The determination of inclination angles should consider the actual processing requirements for the residual height and the machining quality of the cell wall.This study investigates the influence of the inclination angles of a disc cutter on the machining quality of Nomex honeycomb core in ultrasonic cutting and provides guidelines for machining.
