Numerical Simulation of a Heat-Treated Ring Gear Blank

Carburization and quenching of steels in general has been and continues to be an important commercial manufacturing process for steel components. The minimization of distortion, cracking, and residual stresses are major issues that need to be properly understood in order to efficiently produce high quality components. To assist process engineers in understanding the effect process parameters have on these major issues, a numerical study was conducted on an automotive transmission ring gear. The ring gear has substantial ovaling distortion, which cannot always be straightened within the design tolerances of the part thereby leading to a 3–5 percent rejection rate. The purpose of this report is to predict the distortions, microstructural phase changes, residual stresses, and hardness that occur during quenching using finite element techniques. The ABAQUS model from the NCMS Heat Treatment Prediction Program was used to perform the simulations. This report describes a two-dimensional simulation of the gear blank with the wall thinned where the teeth would have been located to represent the proper thermal mass. The gear blank geometry is essentially the same as the gear geometry without the teeth; moreover it has the same dimensions exhibited by the gear. Even though the ovaling caused by distortion is a three-dimensional problem the two-dimensional representation was chosen as an initial step before simulating the more complex three-dimensional gear geometry. The symmetry of the blank can be exploited by allowing fewer elements to be used for the finite element analysis which in turn will decrease the simulation times of the problem. [S0094-4289(00)01103-8]