Establishment Of Vibration And Wear Model For Turning Tool Of Large Pitch Thread

The large pitch screw is used as a key component of heavy equipment to transmit torque and accuracy,and its threaded surface has high precision and reliability requirements.When turning large pitch threads in the production of the company,the tool has a large pitch,a large aspect ratio,and a sudden change in the cutting load,which causes the tool wear to be aggravated,the serviceability is deteriorated,and the process system is strongly vibrated,and the long stroke of the large pitch thread cannot be completed.The vibration wear model of the tool in large pitch thread machining can be used as the basis for evaluating the machining process and improving the quality of the thread surface.This paper considers that vibration belongs to the dynamic system,and tool wear belongs to the tribological category,and it is difficult for the two to establish a relationship directly.The process quantity cutting force is introduced,in which the change of the cutting force is the direct result of the tool wear,and the vibration wear model of the large pitch thread tool is established.Firstly,the tool is simplified by the simply supported beam structure in material mechanics,that is,the cantilever beam model is proposed.According to the force analysis of the left and right cutting edges of the tool,the instantaneous cutting force model of the left and right blades based on the vibration displacement is built.Secondly,a large pitch thread cutting experiment was performed to verify the cutting force model.The vibration acceleration signal is used to correct the theoretical model of the tool vibration displacement.The wavelet packet analysis in MATLAB is used to process the experimental results to obtain the tool vibration.The processed vibration acceleration signal is curve-fitted to obtain the mathematical model of the tool vibration displacement.According to the cutting force experiment,the instantaneous cutting force model of the left and right blades is validated,and the instantaneous cutting force models of different cutting speeds and axial feeds are constructed and verified.Then,in order to reveal the relationship between the cutting force of the left and right edges and the amount of wear on the flank during the finishing of the large pitch thread,the left and right flank wear experiments were carried out.The scanning wear spectroscopy was used to determine the wear pattern of the tool as abrasive wear and bond wear,and the measurement method of the flank wear amount was proposed.A mathematical model for flank wear prediction based on left and right cutting forces is established by BP neural network method.Finally,based on the instantaneous cutting force model under the action of vibration displacement and the mathematical model of the flank wear of the cutting force,the vibration and wear model of the large pitch thread cutter is iteratively obtained to describe the relationship between vibration and wear in the time domain.The experiment was carried out to verify the model.The resu lts show that the model has accuracy.In this paper,the left and right edge vibration wear models of large pitch thread finishing process provide support for the analysis of tool wear prediction and workpiece surface quality in large pitch thread processing,and provide theoretical guidance for enterprises to process large pitch threads.