Study On New Processes Of Precision Forming In Two-way Upsetting-extrusion Of Spiral Bevel Driving Gears

Spiral bevel gears have unique advantages such as better meshing performance,higher bearing capacity,and higher transmission efficiency compared with common bevel gears.In contrast,compared with cutting method,precision plastic forming not only has high material utilization rate and high productivity,but also has a continuously distributed fibrous structure and higher fatigue and wear resistance,so it is expected to obtain gears with longer service period.Although many researchers have studied the precision forming of spiral bevel gears,but there are still many defects such as large forming force,complex mold structure,and insufficient filling of corners.In the paper,a new method of precision forming for two-way upsetting-extrusion of toothless punch is proposed on the basis of the reference to the "(toothed punch)two-way upsetting-extrusion of spur gears" and " die extrusion of spiral bevel gears".Taking the spiral bevel driving gears with a tooth number of 10,a mean normal module of 3.338 and a midpoint helix angle of 50 as the research object for further discussion in the paper.The paper analyzes the process characteristics of the extrusion forming of the spiral bevel driving gears and the different frictional forces on the side surface and the end surface of the precast blank in different extrusion and forming schemes.The finite element simulation software Deform-3D is used to numerically simulate the single and biaxial extrusion forming process of the spiral bevel driving gears with and without shaft.The forming force,load-stroke curve,equivalent stress,equivalent strain and the relevant information are analyzed.The results show that the forming process of the new technology can be divided into three stages: free deformation,full filling,and corner filling.As for the spiral bevel driving gears with shafts in the process of two-way upsetting-extrusion,the maximum value of load is reduced more than 14% compared with its process of one-way upsetting-extrusion.There is no stress concentration if the equivalent stress under the bearing range of dies,the material flowability is good and no damage.For the spiral bevel driving gears without shafts,the toothless punch is significantly superior in terms of load.Which indicates that the blank metal flows more smoothly and the cavity die is more easily filled.The toothless punch and the corresponding female die have simple structure,easy to manufacture and easier to manufacture.In order to verify the reliability of numerical simulation,physical simulation experiments are performed.The key to the design and processing of precast blanks is to ensure that the heights of the cylinders at the upper and lower ends of the circular table are the same.The key to the experiment process is to accurately mark the movement of the upper and lower punches to ensure its movement consistency.Through several physical experiments,the flashless lead spiral bevel driving gears with clear tooth profiles and full filling are obtained.The deficiencies of this study are the lack of specialized blank making procedures and without a deep consideration on how to achieve two-way upsetting-extrusion and forging demould and fail to complete the overall structural design of the production dies.In this study,the precision forming technology of the spiral bevel driving gears is explored.The results of this study can give a certain reference for the research on the near-net shape forming technology of spiral bevel driving gears in terms of high efficiency,energy saving and materials saving.