Investigation of work hardening of flat-rolled helical-involute gears through grain-flow analysis, FE-modeling, and strain signature

Net-shape forming of gears is under investigation by a number of researchers. The proposed new methods would reduce waste through chip elimination. Flat rolling of external-precision involute-helical gears is discussed in the current paper. This method is expected to have the additional advantage of producing stronger gears. The work-hardening effect on the critical regions of gear is investigated through the use of three-dimensional DEFORM finite element models (FEM). The simulation models were calibrated against designed experiments with a specific gear design. Also, current production gears were compared with gears manufactured through the new process. Samples were destructively tested to obtain metallurgical data. Hardness maps and grain-flow photographs were produced for the two groups of gears. Validation of FE modeling has opened the way for optimization of gear-rolling process through virtual design of experiments (DEX). It would be possible to vary FEM inputs such as blank material, gear specification, or die geometry and study the predicted impact on gear tooth strength.