Research On The Key Technology Of Low-rigidity Parts Cutting Jet Support

Low-rigidity parts are widely used in machinery, aerospace, military and other industriesand people’s production and life, such as thin-walled parts, slender shaft are all belong to thelow-rigidity parts category. Due to the characteristics of low rigidity, the parts will generatemachining deformation because of the effect of cutting force, cutting heat and cuttingvibration in the process of cutting machining, we cannot guarantee a good machiningaccuracy and surface quality of the parts. As a new manufacturing technology, water-jettechnology develops rapidly in recent years, has been mainly used in oil drilling, coal mining,industrial cutting, and other fields. When jet impact acting on the object, the energy containedin the jet velocity will be converted into the jet impact force, and in order to effectivelydestroy the object, the impact force and the damaging effects are generally desirable to bebigger as possible.Through the analysis of the current situation in the cutting machining of low-rigidityparts, we know that it’s very effective to use the auxiliary support to enhance the rigidity ofthe workpiece and reduce the machining deformation. While all kinds of auxiliarysupport existing have some limitations. From the perspective of providing auxiliary supportfor the workpiece, this paper presents the idea that set the jet which medium is cutting fluid asthe auxiliary support in the cutting machining of the low-rigidity parts. In the premise of notdestroying the material of workpiece, the cutting force will be reduced or offset by the jetimpact force, so as to play the role in reducing the deformation, enhancing machiningaccuracy and quality of the workpiece.In the paper, the basic theory and hydrodynamic characteristics of water jet has beenresearched. The theoretical calculation formulas are obtained including the jet velocity, jetflow, jet power and jet impact force, and summarizes the pressure distribution area of thecontinuous jet impacting object under the ideal conditions, lays the theoretical foundation forthe simulation analysis and experimental research on the back. The nozzle is a maincomponent of jet generating device. This paper completes the structural design of the nozzlebased on previous studies and in order to satisfy the research needs of the project. Based onFLUENT software to carry out a simulation analysis of the flow characteristics in the nozzle,establishes the jet impact model, and analyzes the impact characteristics of the jet. This paperstudies the effect on jet impact force and jet impact zone of different jet pressure, jet distanceand the diameter of nozzle. On this basis，studies the jet impact force by the experiment,designs the jet generating device and jet impact force measurement device. This paperanalyzes the results of the experiments on the jet impact force generated at each factors, andto compare the results of the experiments with the results of the simulation, analyzes themeasuring error of the experiments. This paper set the slender shaft as the experimentalresearch object, analyzes the reason of turning deformation and the influence on themachining deformation by the turning force, and obtains the main factors leading to thebending deformation. The experimental scheme is designed by the purpose of the experiments.This paper completes the built of the experimental device and determines the cutting parameters, carries out the comparative experiments in the turning of slender shaft supportedby jet, and analyzes the straightness, roundness and surface quality of the two slender shaftcompleted by turning. and confirms that using the jet as auxiliary support in the turning ofslender shaft can play an important role in reducing the deformation and improving themachining quality.