The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining equipment.Most active vibration-isolation systems(AVIS)have been developed based on static loads.When ...The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining equipment.Most active vibration-isolation systems(AVIS)have been developed based on static loads.When a vibration-isolation load changes dynamically during ultra-precision turning lathe machining,the system parameters change,and the efficiency of the active vibration-isolation system based on the traditional control strategy deteriorates.To solve this problem,this paper proposes a vibration-isolation control strategy based on a genetic algorithm-back propagation neural network-PID control(GA-BP-PID),which can automatically adjust the control parameters according to the machining conditions.Vibration-isolation simulations and experiments based on passive vibration isolation,a PID algorithm,and the GA-BP-PID algorithm under dynamic load machining conditions were conducted.The experimental results demonstrated that the active vibration-isolation control strategy designed in this study could effectively attenuate vibration disturbances in the external environment under dynamic load conditions.This design is reasonable and feasible.展开更多
High-precision turning(HPT)is a main processing method for manufacturing rotary high-precision components,especially for metallic parts.However,the generated vibration between tool tip and workpiece during turning may...High-precision turning(HPT)is a main processing method for manufacturing rotary high-precision components,especially for metallic parts.However,the generated vibration between tool tip and workpiece during turning may seriously deteriorate the surface integrity.Therefore,exploring the effect of vibration on turning surface morphology and quality of copper parts using 3D surface topography regeneration model is crucial for predicting HPT performance.This developed model can update the machined surface topology in real time.In this study,the effects of tool arc radius,feed rate,radial vibration,axial vibration and tangential vibration on the surface topography and surface roughness were explored.The results show that the effect of radial vibration on surface topography is greater than that of axial vibration and tangential vibration.The radial vibration frequency is also critical.When vibration frequency changes,the surface topography profile presents three different types:the standard sinusoidal curve,the sinusoidal curve whose lowfrequency signal envelopes high-frequency signal,and the oscillation curve whose low-frequency signal superimposes high-frequency signal.In addition,HPT experiment was carried out to validate the developed model.The surface roughness obtained in the experiment was Ra=53 nm,while the roughness obtained by the simulation was Ra=46 nm,achieving a prediction accuracy of 86.7%.Received 4 September 2022;revised 3 October 2022;accepted 17 October 2022.展开更多
The paper presents the theoretical background for new approaches for achieving high accuracy in finish turning with slender tools. The approaches are developed especially for high-accuracy turning with vibrations- dam...The paper presents the theoretical background for new approaches for achieving high accuracy in finish turning with slender tools. The approaches are developed especially for high-accuracy turning with vibrations- damped boring bars with a length-to-diameter ratio up to 14. The approaches are based on established force models of turning operations and utilize a three-pass scheme where the deflection of the boring bar is calculated and compen- sated for in the final passes. Very good results are achieved in practical machining tests for a great variation of cutting conditions. Experiments show that the typical diameter error is 0.01 mm, even in situation where the tool deflection is 0.3 mm.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62073184,52105490).
文摘The vibration disturbance from an external environment affects the machining accuracy of ultra-precision machining equipment.Most active vibration-isolation systems(AVIS)have been developed based on static loads.When a vibration-isolation load changes dynamically during ultra-precision turning lathe machining,the system parameters change,and the efficiency of the active vibration-isolation system based on the traditional control strategy deteriorates.To solve this problem,this paper proposes a vibration-isolation control strategy based on a genetic algorithm-back propagation neural network-PID control(GA-BP-PID),which can automatically adjust the control parameters according to the machining conditions.Vibration-isolation simulations and experiments based on passive vibration isolation,a PID algorithm,and the GA-BP-PID algorithm under dynamic load machining conditions were conducted.The experimental results demonstrated that the active vibration-isolation control strategy designed in this study could effectively attenuate vibration disturbances in the external environment under dynamic load conditions.This design is reasonable and feasible.
基金support from the National Natural Science Foundation of China(Nos.51775147 and 52005133).
文摘High-precision turning(HPT)is a main processing method for manufacturing rotary high-precision components,especially for metallic parts.However,the generated vibration between tool tip and workpiece during turning may seriously deteriorate the surface integrity.Therefore,exploring the effect of vibration on turning surface morphology and quality of copper parts using 3D surface topography regeneration model is crucial for predicting HPT performance.This developed model can update the machined surface topology in real time.In this study,the effects of tool arc radius,feed rate,radial vibration,axial vibration and tangential vibration on the surface topography and surface roughness were explored.The results show that the effect of radial vibration on surface topography is greater than that of axial vibration and tangential vibration.The radial vibration frequency is also critical.When vibration frequency changes,the surface topography profile presents three different types:the standard sinusoidal curve,the sinusoidal curve whose lowfrequency signal envelopes high-frequency signal,and the oscillation curve whose low-frequency signal superimposes high-frequency signal.In addition,HPT experiment was carried out to validate the developed model.The surface roughness obtained in the experiment was Ra=53 nm,while the roughness obtained by the simulation was Ra=46 nm,achieving a prediction accuracy of 86.7%.Received 4 September 2022;revised 3 October 2022;accepted 17 October 2022.
基金Research Council of Norway for supporting this work through the"SmartTools"project(Grant No.219309/030)
文摘The paper presents the theoretical background for new approaches for achieving high accuracy in finish turning with slender tools. The approaches are developed especially for high-accuracy turning with vibrations- damped boring bars with a length-to-diameter ratio up to 14. The approaches are based on established force models of turning operations and utilize a three-pass scheme where the deflection of the boring bar is calculated and compen- sated for in the final passes. Very good results are achieved in practical machining tests for a great variation of cutting conditions. Experiments show that the typical diameter error is 0.01 mm, even in situation where the tool deflection is 0.3 mm.
