| Titanium alloy has the advantages of low density,small deformation coefficient,high specific strength,corrosion resistance,high temperature resistance and so on,it is widely used in aerospace,ships,cars and rail transportation and other important areas.In these applications,there are a lot of threaded connection hole needs to process,but because of the titanium alloy with high coefficient of friction,viscosity and low thermal conductivity and characteristics,the tap on the titanium alloy material when tapping,low processing efficiency,cutting force and unstable quality of the disadvantages.Spiral milling technology is a new type of thread processing technology with the development of numerical control technology.It has a great advantage in the processing precision and efficiency,and it has been applied in the machining of the machining process.In this paper,the kinematic analysis of screw thread milling is analyzed.Considering the chip thickness variation of helical thread milling,two-dimensional finite element model was established.Studied the distribution of temperature field in cutting tool,chip and workpiece of Screw thread milling process,and the effect of cutting speed on the cutting temperature is explored.The simulation results show that:The maximum cutting temperature in the second deformation zone.This area cut chips and the tool temperature are higher and the cutting chip temperature is higher than that of the cutting tool and the workpiece,suggesting that the heat generated in the process of screw thread milling most of the inflow chip,lead to the chip temperature increases rapidly;tool on the highest temperature appears in the tip distance to a distance.In order to study the change rule of chip shape and cutting force in the process of screw milling of titanium alloy,The finite element model of thread milling which can reflect the thread cutter rotation,around the center of the threaded hole,the axial feed motion synthesis of revolution is established.The simulation results show that:Due to the thread milling process,cutting force in the cutting force to the force is always greater than the radial,and the axial feed rate is very small,so in the thread milling cutting force,cut to the greatest force,radial force times,minimal axial force.And in the thread milling cutting to force,radial force and axial force increased with the increase of feed per tooth increases.With the increase of cutting speed and reduce,and feed per tooth for milling three to force the influence is bigger,and the cutting speed of three direction of milling force has little impact.Spiral milling thread belongs to intermittent machining,the machining of chips for short cut,is a good controllability of chip shape,and chip shape with each tooth feed rate increases its length,thickness,width,there is a certain growth.The accuracy of the simulation results is verified by two aspects of the cutting force and chip form.The results show that the maximum error of tangential cutting force is 14%,and the radial cutting force error is 6%.The simulation results show that the chip has similar characteristics.The finite element model is established in this paper,the cutting force,cutting temperature and chip morphology were analyzed,and the accuracy was verified by experiments,which could provide a strong support for the practical machining of titanium alloy screw thread. |
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