Research On Cold Extrusion Forming Method Of Integral Gear Ring Of Wheel Reducer

Ring gear is one of the important transmission components in planetary gear transmission,which is widely used in industrial fields due to its advantages such as high transmission power,high load carrying capacity,strong impact and vibration resistance,and smooth transmission.At present,the gear ring is mainly obtained by mechanical processing methods such as gear shaping,turning,and broaching.There are a series of problems such as low processing efficiency,high material loss rate,and rapid tool wear,which are difficult to meet the needs of mass production.Cold extrusion technology is a highly efficient,energy-saving and material reduction plastic forming method suitable for mass production.The gear ring formed by cold extrusion technology has the characteristics of high strength and good surface quality.Compared to the general combined gear ring,the integral gear ring has higher strength and longer service life.However,this structure cannot be formed using the traditional closed cold extrusion process,and can only be processed using the open cold extrusion process scheme.When forming in this scheme,part of the blank is not constrained by the mold.When the forming force is too large,the internal stress of the metal reaches the yield limit,it is prone to local upsetting,instability,and other forming defects;At the same time,the metal flow in the cold extrusion forming process of the gear ring is complex,which cannot ensure the forming quality and precision of the inner teeth of the gear ring,and there is also a requirement for effective tooth length of the inner teeth of the gear ring.Therefore,how to control the forming force,avoid forming defects,improve the forming quality and precision of the inner teeth of the gear ring,and ensure that the effective tooth length meets the design requirements is the key to the open cold extrusion forming of the integral gear ring.In this paper,the structural characteristics of the integral gear ring of the wheel reducer are analyzed,and an open reverse extrusion forming process scheme is proposed to solve the technical difficulties in the formation of the inner gear ring teeth;The open reverse extrusion forming process of the integral gear ring was numerically simulated using the DEFORM-3D finite element software,and the effects of process parameters such as the gap between the blank and the punch,the width of the root of the punch inlet,the length of the sizing belt,the punch inlet half angle,and the length of the guide zone on the metal forming were analyzed;The response surface method was used to optimize the main process parameters and determine the optimal combination of process parameters;The influence of elastic recovery of extrusion parts and elastic deformation of molds on the tooth profile accuracy of inner teeth of gear rings was studied,and a method of mold modification was proposed to improve the tooth profile accuracy;The distribution law of the tooth alignment error in the gear ring is studied,and a cold shaping process method is proposed to achieve the purpose of improving the tooth alignment accuracy of the gear ring.The effect of the finishing amount on the tooth alignment accuracy is also studied;Finally,based on the results of parameter optimization,a cold extrusion mold was designed and manufactured,and an open reverse extrusion process experiment for the integral gear ring was conducted.The process test results show that using the optimal combination of process parameters to conduct process tests can effectively reduce the forming force,and the cold extrusion parts obtained from the tests have a full tooth shape,good forming quality,and both the forming accuracy and effective tooth length meet the design requirements.The experimental results verify the feasibility of the process plan and the correctness of the numerical simulation.