Research On Near-Net Forming Process Of Spiral Bevel Gear Precision Forging Based On Deformation Uniformity

As a key component of mechanical transmission,spiral bevel gears are widely used in automobiles,ships,aircraft and other fields because of their high load-bearing capacity and smooth transmission.At present,the traditional spiral bevel gear processing method is still based on cutting,this processing method needs to use the tool to cut off the excess metal material in the tooth blank,on the one hand,causing material waste and increasing the production cost;on the other hand,the cutting process will cut off the metal flow line of the tooth blank and thus reduce the strength and service life of the gear.The spiral bevel gears produced in this way have a continuous and uniform metal flow line,which significantly improves the strength and service life of the gears;meanwhile,the spiral bevel gears have a complex tooth profile and are prone to uneven deformation during the forming process.Therefore,it is of high practical value to carry out the research on the spiral bevel gear precision forging near net forming process based on the uniformity of deformation.In this thesis,the whole process of spiral bevel gear net forming is studied by numerical simulation and theoretical analysis,and its deformation uniformity and metal flow evolution are analyzed and the process parameters are optimized.The main research contents are as follows:(1)The dimensions of the bar stock required for the finish forging of the spiral bevel gear were determined.Based on the parts drawing of the spiral bevel gear reverse design its cold forging parts drawing,hot forging parts drawing,based on this drawing to establish a three-dimensional model of the spiral bevel gear hot forging parts,so as to obtain the volume of the hot forging parts,and finally based on the principle of constant volume during plastic deformation to design the bar size of the spiral bevel gear.(2)Numerical simulation and analysis of the upsetting and punching processes were carried out based on the uniformity of deformation.Uniformity analysis was carried out for both upsetting and punching processes: 2D-Forming in the finite element software Deform was used to numerically simulate the evolution of metal flow lines and strain distribution in the upsetting and punching processes respectively.The reasons for the different changes of metal flow lines were explained by their metal material flow.(3)Numerical simulation and parameter optimization of the ring rolling process based on the deformation uniformity were carried out.Numerical simulation of the ring rolling process was carried out on the platform of Ring Roll in Deform,and the causes of defects such as tooth billet end depression and uneven deformation and the evolution of metal flow were analyzed;the parameters such as drive roll speed,core roll feed speed,initial temperature of ring billet and drive roll diameter were optimized by using orthogonal experiments with deformation uniformity and end depression as evaluation indexes: By analyzing the extreme difference and value,the influence of each parameter on the evaluation index is studied,and the optimal combination of parameters is thus determined,and the tooth billet rolled by this combination of parameters ensures the uniformity of internal deformation and the small degree of end depression.(4)Numerical simulation and parameter optimization of the forging process were carried out based on the deformation uniformity.3D-Forming in Deform was used to simulate the deformation process of the final forging process of spiral bevel gears,and the effects of process parameters such as tooth blank temperature,strike speed,friction factor and die temperature on the deformation uniformity of spiral bevel gears were studied separately.The combination of process parameters that can make the spiral bevel gears have better deformation uniformity is finally obtained.(5)Processing test verification was carried out.Based on the optimized process parameters,the ring rolling and forging gear processing tests were carried out,and the results showed that the test obtained a regular shape,accurate size and high flatness of the end face of the tooth billet,the spiral bevel gear filled with full and smooth metal flow,which verified the feasibility of the optimization of the parameters in this thesis.