| Because high strength alloy steel belongs to"hard-to-machine material",during the cutting process,its' particularities may take many problems such as chip-breaking is difficult,cutting force of per unit area are large,the cutting temperature is high and vibration-buckling is easy to happen.In the process of high strength steel hole machining,it is time-consuming and labor-consuming for machined material to find suitable processing parameters by using traditional cutting test methods,meanwhile the cutting efficiency is low and the controllability is poor.Based on the above problems,this paper focuses on drilling of high strength alloy steel 34CrNi3MoV,it mainly including the following aspects:Firstly,the current research status of drilling hard-to-machine materials at home and abroad is introduced.The process of chip formation,deformation and breaking from microscopic and macroscopic perspectives is analyzed,and the evaluation index of chip shape is established,meanwhile the main influencing factors of chip-breaking is concluded.Secondly,the metallographic structure of test steel 34CrNi3MoV and its chemical composition and main mechanical properties is analyzed.According to the principle of drilling,we established the simulation model of drilling this material by The Wave AdvantEdge finite element simulation software.The influence of cutting parameters and tool geometry parameters on cutting force,cutting temperature,and torque and chip shape has been studied by using single factor experiment method.We measured the chip geometry parameters and calculate the related morphology evaluation index by using post-processing function,and analyze the influence of each factor on chip shape.Then,by comparing the simulation results with single factor experiments,we carry out error analysis and verify the accuracy of the simulation model.Contrast the collected chips from experiment with simulated chips,we find they are highly similar.We can get the cutting parameters have a great influence on the chip shape,and different combinations of tool speed and feed rate can gain different chip shape.In a certain range,it is easy to get the higher rate of the chip-breaking and form unit chips,under the faster speed and the larger feed.Change cutting parameters can help chip-breaking.Finally,due to the high hardness and yield strength of the material,vibration instability occurs easily during the drilling.Therefore a Four-Degree-of-Freedom dynamic model of drill bit during the drilling system processing is established,the working conditions' mode shapes and extract the relevant modal parameters can be got by using ANSYS software.Then,according to the regenerative chatter theory,analyses the influence of chatter on cutting thickness and calculate the dynamic cutting force according to the dynamic cutting thickness,after that based on the transfer function drilling stability model can be established.Eventually we obtain the stability lobes diagram of the drilling system by using MATLAB numerical analysis software.In this paper,through analyzing the chip shape,cutting performance and vibration characteristics,when drilling process this material.The influence of cutting parameters,tool geometry parameters and other factors on cutting performance and chip shape can be obtained,meanwhile,the stability of system vibration under the condition of well chip breaking and chip removal also can be obtained,which is valuable for improving processing efficiency and processing technology,besides also has certain guiding significance. |
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