Experimental study on the axial-infeed incremental warm rolling process for spline shaft production

In this work, the axial-infeed incremental warm rolling process is introduced to the production of spline drive shaft with 42CrMo steel. To understand the role of warm forming temperature, the comparative experiments were conducted using the cold and warm axial-infeed incremental rolling process. Compared to the cold rolling process, the axial feed force is decreased 36.6% by warm rolling process. Meanwhile, the microstructure and hardness tests show that the results of the spline shafts formed by warm rolling are significantly better than those formed by cold rolling. Due to the effect of warm forming temperature, the formed spline shafts have obtained significant grain refinement, fiber texture formation, and hardness increase in the tooth profile area. Finally, the axial-infeed incremental warm rolling process has been used in actual production of semi-axis and the results are compared to the conventional production process. Through the pilot production, the productivity of spline shaft is increased 35.5% by the axial-infeed incremental warm rolling process, respecting to the conventional production process. The results in this work suggest that the axial-infeed incremental warm rolling process has great potential in mass production of spline shaft.