Theoretical and experimental study on influencing factors of rabbit ear in the gear forced throughfeed rolling process

Attainable gear quality is a crucial criterion for the broad industrial application of the gear roll-forming process. One of the main defects in gear rolling process is the rabbit ear, which affects the effective tooth depth of the formed workpiece and the material utilization rate. To further understand the influencing factors of rabbit ear, this paper proposes analytical models of relative sliding distance and frictional shear stress to explain the material flow on the tooth flank of the workpiece. The influence of rolling parameters (rotational speed of rolling tools, lubrication, rotational direction of rolling tools), number of workpiece teeth, and positive addendum modified rolling tools on rabbit ear was studied theoretically based on the established models and a case study. Finally, experimental results were displayed to verify the above-mentioned analysis. The results reveal that better lubrication, higher rotational speed, and reverse rotation of rolling tools contribute to weakening the rabbit ear effect. Moreover, the rabbit ear height in case of z(2) = 70 decreases by 14.2% compared to that in case of z(2) = 46 due to reduced gear ratio. Additionally, rabbit ear height formed by rolling tools with a positive addendum modification coefficient of 1.0 amounts to approximately 48.3% of that generated by rolling tools having standard teeth in the gear forced throughfeed rolling process.