| Pipeline intersecting structures can be seen everywhere in pipeline construction.The pipeline intersecting structure is formed by welding of two pipes,which takes up more and more shares in modern pipeline engineering.The existing variable angle groove adopts flame machining and the groove surface quality is poor,which limits the automation process of pipeline engineering.Based on the research background of machining variable angle groove,this paper studies the machining principle and technology of machining variable angle groove surface by side milling.The research focuses on the mathematical modeling of variable angle groove surface,the machining principle and path planning of cone milling cutter side milling of special numerical control machining equipment,and the research work and innovative results are as follows.Firstly,parametric characterization and solid modeling of the variable angle groove surface are completed.Based on the analysis of the requirement that the automatic welding machine needs to weld the same filler area in different groove sections,the feature curve of the variable angle groove surface is modeled based on the geometric parameters of the pipeline intersection.The NURBS curve is used to reconstruct the characteristic curve,and the mathematical model of straight grain surface representation of the variable angle groove surface is established.Based on the evaluation index of free-form surface,the machining evaluation index of the variable angle groove surface is proposed,and the mathematical modeling of the variable angle groove surface is completed.Secondly,the tool path is optimized for special CNC machining equipment and taper milling cutter.This paper analyzes the existing special numerical control machining equipment and establishes the machine tool motion model.Based on the motion model of machine tool and cutting tool,a method for calculating the overcutting of single cutting position using the principle of space geometry is put forward,and the optimization objective function of single cutting position is established by using this method.Then,the virtual machine tool simulation machining experiment and the machining experiment and in-machine measurement based on the special numerical control machining equipment are carried out.Simulation software is used to model and debug the special nc machining equipment.Based on the special numerical control machining equipment and the parameters of existing taper milling cutters,the machining procedure of variable angle groove surface is presented.On this basis,the tool trajectory is planned,the optimized data is used for numerical control program,and the simulation and experimental machining.Finally,the machine measurement system is built to measure the groove surface.Based on the existing special CNC machining equipment in the machine measurement system,error analysis and error compensation model is proposed to compensate the measurement data.In this paper,the measured results of the variable angle groove surface are good and accord with the evaluation index of variable angle groove surface.After a certain degree of understanding of the principle of automatic welding and the principle of side milling,this paper applies the method of side milling to the machining of the variable angle groove surface,which can promote the process of automation in welding field. |
