螺旋锥齿轮的无根切最小变位系数

THE MINIMUM MODIFICATION COEFFICIENT OF SPIRAL BEVEL GEAR WITHOUT UNDERCUT

应用空间啮合理论和优化方法得到各种参数的螺旋锥齿轮无根切最大齿根角θｆｍａｘ和分锥角δ的关系曲线。验证了美国齿轮设计标准的设计曲线，并扩充了其使用范围。通过曲线拟合，得出实用的螺旋锥齿轮无根切最小变位系数计算公式，为设计者提供了准确的设计依据。

Spiral bevel gear is a very important element in drive lines of various machines such as tractors, trucks etc. It is a good method to use nonzero modification to increase tooth strength or to improve gearing properties in design of spiral bevel gears. To avoid undercut is the most basic requirement. Thus the minimum modification coefficient for nonundercut gears must be determined. However there is not a clear and accurate formula for calculating its parameters even in standards of modern industrial countries. In this paper, based on the theory of three dimensional gearing, the fmax curves without undercut for Gleason type spiral bevel gears are derived by the optimum method of penalty function. The formula for calculating the minimum modification coefficient at the condition of nonundercut is given through the mathematical treatment of the results. It is proved that the results of calculating by the principle of gearing are true and reliable. Owing to their good accuracy, they are useful to both the manual design and CAD and provide a foundation in design of spiral bevel gears without undercut.