| The laminated component of the air rudder of space vehicle is connected by riveting,so riveting holes need to be made for the laminated assembly structure.Due to the low efficiency of manual drilling and riveting process,which restricts the improvement of production capacity,the robot has large working space and high flexibility,and is widely used in drilling and processing.Due to the weak rigidity of the robot under the action of cutting force,it is easy to cause tool chatter,and the secondary cutting edge on the machined surface leads to the aperture aberration.In order to study the effect of tool vibration amplitude on the accuracy of laminated aperture,a tool flutter mechanism model of robot drilling laminated plate was built,and the accuracy of laminated aperture was predicted by robot dynamics.The prediction model of aperture accuracy based on data and mechanism is established,and the mechanism model is used to modify the data to drive the prediction results and improve the accuracy.A prototype system for parameter optimization of robot drilling is developed to optimize the precision of drilling overlapping holes.The feasibility of the model is verified by the experiment of metal laminated plates,and the key technologies such as automatic drilling of laminated holes are broken through.The research results of this paper are carried out in four aspects:(1)Establish a tool flutter mechanism model for robot drilling of laminated sheet metal.A robot drilling force model was built based on the cutting edge element method,and the influence of factors such as material cutting coefficient,bit axis line offset and drilling force fluctuation were considered as the drilling force excitation function of the chatter model.The stiffness model of the robot was established based on the flexibility ellipsoid method,and the direct stiffness coefficient in the direction of load bearing at the end of the robot was solved.A two-degree-of-freedom tool flutter mechanism model was constructed,and the correlation between tool flutter and hole making accuracy was studied,so as to predict the accuracy of each aperture in the stack.(2)Study the mechanism and data fusion of aperture accuracy prediction method.A dynamic prediction model was established based on 1D-CNN method.The processing factors affecting the aperture accuracy were considered through sensor signals.The prediction accuracy results were the training parameters of data domain.The time-frequency domain method is used to preprocess the sensor signal and extract the characteristic values associated with the aperture accuracy.The mechanism model was constructed to predict the aperture value,and the eigenvalue and the predicted value were the training parameters of the mechanism domain.A fusion prediction method of aperture accuracy was constructed.Different prediction weights were assigned to the concerned part of the training parameters by the attention mechanism method,and the prediction weight ratio was adjusted to make the fusion prediction model have higher prediction accuracy.(3)Develop the prototype system for optimizing the machining parameters of robot hole making and carry out the experimental verification of metal laminated hole making.The optimization model of robot drilling parameters was established based on genetic algorithm.The least square support vector machine was used to iteratively optimize the training parameters and output the optimal solution of machining parameters.The prototype system for optimization of machining parameters was developed,and the state visualization of actual hole equipment and prediction of aperture accuracy were carried out through Winform form.The closed-loop control of hole efficiency and actual hole accuracy was improved through parameter optimization.The accuracy of the fusion prediction model is 93.7% through experiments,and the error of the aperture accuracy is reduced by 25% on average before and after drilling by using parameter optimization model comparison.The relevant methods constructed in this paper achieve active riveting quality control of aerospace precision components,improve assembly quality and production efficiency,and have important theoretical significance and application value for improving the application effect of industrial robots in the processing field. |
