| With the diversification,miniaturization and mini microminiaturization of the national defense and military equipment,device of aerospace,automobiles,micro-electromechanical system components and civil products,the development of sophisticated and efficient micro-deep hole processing technology has become the important foundation for the replacement of the product and development of the new industries.At the same time,it has been a problem which is solved urgently in the field of machinery manufacturing.It has become the key to meet the requirement of the national economy and market-oriented exploration to explore the precise and efficient processing technology,to sophisticate the tools and equipment,to study more advanced processing techniques and to perfect the quality evaluation system for the deep hole machining.In this paper,the precision and surface quality of gun drill are seemed as the main lines.Numerical analysis,simulation and experimental are used to research the formation mechanism and variation regularity of errors of roundness and straightness deeply.The surface roughness,the degree of hardening of the layer and the distribution of the microstructure of the surface layer are mainly studied to further expand the application of gun drill.Based on the mechanism of the deep hole drilling and the geometric characteristics of the tool,a micro-drilling model of the inner and outer of gun drill is established by binary rectangular cutting model.The axial force,the radial force and torque formula is obtained through the numerical integration method.The effects of gun drill geometry parameters(relief angle,breadth of tooth,working approach angle)and feed rate on the total axial force and total drilling torque of gun drill is analyzed by numerical simulation to provide the guarantee for optimizing the structure of tool and drilling technology.The forming mechanism of roughness error in gun drill deep hole processing is deeply analyzed and the model of roundness morphology and roundness error numerical model are established.The effects of the spindle error and the workpiece vibration is studied by the half frequency effect on the roundness,multi frequency effect on roundness,amplitude and frequency effect on roundness and phase effect on roundness respectively to estimate the number of lobes and the final shape of the hole contour in the actual machining.And the optimal method is predicted by the FFT method to predict the influence on the roundness caused by the cutting speed,feed rate and the depth of hole(aspect ratio).According to the single factor test,the roundness error under different processing condition is tested to reveal the law of the influence of the cutting speed,feed rate,and depth(aspect ratio).And the result is compared with the prediction from roundness error numerical model to verify its rationality.According to the actual situation of gun drilling,the influence law of each controlling factor on the deviation of straightness in deep hole machining is deeply analyzed and the influence rule of center deviation of guide sleeve and auxiliary support device and machining parameters on straightness deviation in the gun drilling system are emphatically studied.According to the Euler beam theory,the straightness error models of the center deflection of the guide sleeve and the auxiliary support device are established.Through the single factor test,analyzing the influence law of each control factor on the straightness deviation,verifying the validity of the prediction model,and analyzing the change rules between cutting speed,feed speed and the hole straightness,so that to optimize processing parameters.The influence law of cutting parameters on hole's surface roughness,microstructure and microhardness is studied by the SEM,optical microscope and microhardness tester and the mapping relation between the tool wear morphology and the pore surface micro structure is discussed. |
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