Study On Vibration Characteristics Of Process System For Turning Large Pitch Internal Thread

Large-pitch threaded parts are important components in various heavy-duty turning and milling machines such as CNC gantry end mills.The vibration characteristics of the turning process system for large pitch internal threads are studied in this paper,and the basis for identifying the vibration characteristics of turning large pitch internal threads is proposed,and the prediction model of cutting force and vibration displacement is established to ensure the turning stability of turning large pitch internal threads,as follows.Firstly,a study on the process and vibration sources of turning large pitch internal threads was conducted.The analysis of the process system reveals the sources of vibration in turning large pitch internal threads,and establishes the excitation model of each process system.The traditional thread turning process is no longer fully applicable due to the characteristics of high feed,large depth of cut,and long overhang of the tool bar.Secondly,the vibration characteristics of the subsystem of the turning process of large pitch internal threads were studied.The tool tip point is initially selected as the vibration reflection point of the process system,the vibration characteristic value is selected,and the prediction model of the tool tip amplitude of the process system under different parameters is constructed;the finite element modal and harmonic response simulation model is established to obtain the resonance interval of the process system and provide the method to avoid resonance;the tool and workpiece are The workpiece and tool vibration displacement equations under the action of theoretical cutting force are established by dynamic modeling.Again,the vibration characteristics during turning of large pitch internal threads were studied.A cutting force simulation test was designed to verify the accuracy of the simulated force data through a large pitch internal thread cutting force verification experiment,and a cutting force regression model was established using the simulated force data from the orthogonal simulation test and the significance of the model was verified through significance testing.The optimal cutting parameters were obtained by using particle swarm algorithm,and the vibration displacement equation under the optimal cutting parameters was established.Finally,the vibration suppression measures of the process system for turning large pitch internal threads are proposed.The effectiveness of the follow tool holder for long internal thread turning is analyzed,and the workpiece deformation and amplitude with and without the follow tool holder are simulated by means of finite element simulation to achieve the goal of vibration suppression.The vibration characteristics of turning large pitch internal threads are studied to reveal the vibration response characteristics of turning with high feed and large depth of cut,which provides an effective basis for evaluating and controlling the stability of turning large pitch internal threads.