Accurate Tooth Lead Crowning without Twist in Cylindrical Helical Gear Grinding

Abstract

Form grinding is a popular finishing process in manufacturing cylindrical gears with tooth flank modification. The tooth flanks are usually twisted when a lead crowning is performed only through additional radial motion during double flank grinding. For solving the problem, this paper proposes a method for application of tooth lead crowning without twist in cylindrical helical gears based on the idea of tooth form correction for spiral bevel and hypoid gears. In this method, the motion of each following axis is formulated as a six-order polynomial of the leading axis position and the sensitivity of tooth ground flanks with respect to the changes in the motion polynomial coefficients is analyzed. Polynomial coefficients for lead crowning are optimized by minimizing the errors between the ground tooth flanks and the target tooth flanks. The proposed optimization procedure uses dynamic sensitivity matrix instead of static, and it can obtain optimum solution with fewer steps stably. Simulation and experimental results demonstrate the effectiveness of this twist preventing method.