Analysis of uncut chip geometry and cutting force in gear skiving process using a cylindrical tool

Power skiving is a highly productive method for manufacturing gears, particularly internal gears. However, the conventional conical tool has always presented a significant challenge due to its limited tool life caused by resharpening errors and uniform wear characteristics. Although the cylindrical tool is expected to offer improved accuracy with error-free flanks, there still exists a lack of systematic knowledge for process design and optimization. In this paper, a geometric penetration calculation for gear skiving available in the literature is used to calculate the uncut chip geometry and cutting force of the skiving tools by employing the multiple radial infeed strategy. The numerical analysis demonstrates that an increase in tool offset leads to a transition from V-shaped to L-shaped uncut chip geometry along the tooth direction, resulting in a decrease in tool-chip contact area on top edges. A comparison of conical and cylindrical tools regarding their contact areas with the chip indicates that during each pass, all top edges of the conical tool are involved in gear flank formation while using cylindrical tools reduces cutting time percentage related to top edges by an average of 35% across three passes. In comparison to conical tool, cylindrical tools exhibit reductions in maximum chip thickness by 3.0%, 7.2%, and 3.8% respectively in Pas. 1st, Pas. 2nd, and Pas. 3rd, which consequently leads to a decrease in peak cutting force by 5.7%, 10.1%, and 19.3% respectively for each pass. The experiment was conducted on a Profilator skiving machine using a non-carburized 42CrMo workpiece and tools made from W2Mo10Cr4Co8 material coated with AlCrN. The results demonstrate that using cylindrical tools has the potential to extend tool life compared to conical tools due to the load homogenization in gear skiving.