The Precision Forging Process And Die Design For Spur Gear

The spur gear, which has the requirement of high dimensional accuracy, good surfacequality and excellent property, is a typical component used in the automobiletransmission system. The conventional cutting process has brought lots of problems suchas low material utilization, high cost and poor mechanical properties. Precision forgingprocess is an effective method against it.Based on the process analysis of spur gear with large module, the warm forging-coldsizing compound processing method was proposed in the paper, together with processroutine. The analysis and comparison on three different warm forging die schemes werecarried out by means of numerical simulation using finite code DEFORM. The doubledirection extrusion under the condition of free floating die was chosen as the mostappropriate one. In addition, the influence of some process parameters on forging pointedto the scheme mentioned above were discussed. It was demonstrated that800℃~850℃was the reasonable billet temperature and the web was located in the middle of theforging part was the best design for the forming of gear. Besides, a novel spur gear coldforging scheme was advanced utilizing the radial forging process, which had been provedthe feasibility for the complete filling of die cavity.The die for warm forging was designed according to the result of numerical simulation.To check the strength of combination die during the forging method, the stress analysiswas done using finite code ABAQUS. The die for hollow divided flow cold sizing wasalso developed to meet the need of subsequent experiment.Reverse gear is one of spur gears with boss, and its teeth have back taper. However,the forming of back taper through machining or sizing is extremely difficult. The shapingof teeth with back taper by precision forging was presented in the paper，the warm-coldcompound processing method and its manufacturing process routine were also putforward. The whole forging process flow was evaluated through adopting numericalsimulation to design die for experiment.Process experiment was conducted for testing of warm forging process for spur gearwith large module. The under-fill and oxidization of steel forgings in processing was alsodiscussed and the solutions of these defects were given. The results of paper haveimportant practical significance and guiding role in promoting the advancement of thegear precision forging technology.