| Gun drill is one of the main processing methods of deep hole processing,which has the advantages of small hole processing,high processing accuracy and high processing efficiency,and is widely used in the field of mechanical processing.High nitrogen austenitic stainless steel 15-15 hs Max is used in the processing of oil drilling parts because of its excellent corrosion resistance and good comprehensive mechanical properties.In this thesis,the machining characteristics of 15-15 hs Max are analyzed firstly,and then the drilling process of15-15 hs Max is modeled and simulated by using finite element simulation method,and combined with the process experiment to optimize the processing parameters,and finally the processing experiment to verify the rationality of the process parameters combination.The main contents of this thesis are as follows:Firstly,the cutting force and torque of the drill bit during machining are analyzed.The3 D cutting model was simplified into a 2D cutting model,the gun drill was decomposed into several micro-tools,and the torque and drilling force of each micro-tool were solved.Finally,the torque and drilling force of the complete gun drill bit were obtained by integrating the torque and drilling force of each micro-tool.Secondly,the reasons affecting the deviation of machining hole axis are analyzed.The best hole straightness can be obtained by rotating workpiece and tool.The straightness of machining hole is the worst when the workpiece is fixed and the tool is rotated.The selection of processing mode needs to be based on the processing site conditions.According to eulerBernoulli beam theory,a mechanical model of drill pipe during machining was established to solve the bending moment of drill pipe,and the relationship between eccentricity and axis deviation of guide sleeve and tool support frame was further solved.The effect of cutting fluid on the deflection of hole axis was solved by simplifying the drill pipe as a simply supported beam model.In order to solve the problem of machining axis deflection caused by tool support frame eccentricity,the structure optimization design of tool support frame was carried out.Then Deform-3D was used to simulate the drilling process,and the changes of drilling force,drilling temperature and chip morphology were analyzed during the machining process.The simulation results show that the drilling force and drilling temperature will increase with the increase of drilling depth,and the drilling force reaches stability when all the cutting edges are involved in cutting.The highest point of drilling temperature is the cutting edge of the tool and the bottom of the chip of the workpiece.The effects of rotational speed and feed speed on the axial force,cutting temperature and equivalent stress of the drill bit are further analyzed through simulation experiments.The combination of process parameters is optimized by considering the service life and processing efficiency of the tool.Finally,based on the cost consideration,the pre-processing experiment of titanium alloy TC4 was conducted to avoid the economic loss caused by the scrap of the workpiece due to the unreasonable setting of process parameters,and to provide reference for the processing of15-15 hs Max workpiece.According to the process parameters obtained from the preexperiment and simulation experiment results,the machining hole diameter is 5 mm,the length of the machining hole is 1200 mm,and the axis deviation of the machining hole meets the processing requirements.The process parameters can be obtained by combining finite element simulation experiment with process experiment,which can effectively save time and reduce the actual processing experiment cost.The research results of this thesis have certain reference value and significance for deep hole machining of 15-15 hs Max. |
PDF Full Text Request