Double-sided Continuous Machining Method And Equipment For Aircraft Structural Parts

Generally,for the aircraft structural parts,the structure is complex and the material removal rate is high.Due to the redistribution of inner residual stress after machining,the parts often face serious deformation and they can even be scrapped in the worst case.So it is vital to control the machining deformation for the forming process of aircraft structural parts.The existing deformation control methods are mainly based on deformation prediction to control the machining deformation by optimizing the machining process in an offline way.However,for the development of aircraft structural parts,due to the influence caused by many uncertain factors,how to control the machining deformation effectively has become one of the technical bottlenecks.Aiming at the problem that it is difficult to control the machining deformation effectively during the forming process of aircraft structural parts,a kind of double-sided continuous machining method and device has been deeply studied in this thesis.The main works are as follows:(1)Based on floating clamping,a kind of double-sided continuous machining method for the aircraft structure is proposed.In this method,the blank is divided into direct machining layer and dynamic adjusting layer along the thickness direction.Under the mode of floating clamping,the alternative double-sided continuous machining process is studied by using front-back cooperative optimization strategy.A kind of corresponding clamping device has been developed and the doublesided continuous machining process can be realized by using one clamping,which provides a new idea for machining deformation control of the aircraft structural parts.(2)Based on deformation data,a kind of dynamic allowance allocation method of double-sided machining is proposed.A Kalman-filter-based online deformation prediction model is established by detecting deformation data in the machining process.According to the result of deformation prediction,the relative position of the part in the blank is determined by selecting the least deformation cutting layer step by step on both sides.By using this strategy,the machining allowance of both sides can be dynamic distributed.The experimental results show that this method can significantly reduce the machining deformation.(3)A kind of optimization method of double-sided finishing sequence is studied.The optimization model of double-sided finishing sequence is established.Firstly,choose the workpiece stiffness as optimization objective to find the finishing sequence by simulation to make the remaining workpiece possess the maximum stiffness.Then,the small machining areas are merged to increase the machining efficiency,which is a secondary optimization of the machining sequence.The effectiveness of this method in controlling machining deformation is verified by comparative experiments.(4)Based on the above researches,a hardware and software system of double-sided continuous machining for the aircraft structural parts is developed.The experiment result shows that the machining deformation of typical beam parts is 0.034 mm,which is a 41.3% reduction in deformation when compared with the traditional method.