The purpose of this paper is to provide the calculation methods on worm
addendum thickness and curvature interference limit line, and find the
feasible value range of the technological crossing angle to avoiding
addendum sharpening and curvature interference for enveloping
cylindrical worm drive with arc-toothed worm. In accordance with the
features of the proposed worm, the mathematical models of cutting and
working are established. Based on this, the tooth profile geometry of
the worm in its axial section and the worm addendum thickness are
obtained by geometric analysis and calculation, and then, the feasible
value range of the technological crossing angle is given. In virtue of
vector rotation and elimination method, the nonlinear equation with one
variable for solving the interference limit line is determined. In the
process of solving nonlinear equation, the method of geometric
construction is used to judge the existence of solutions and provide an
initial value for the subsequent iterative calculation. The numerical
example results show that with the increases of the technological
crossing angle, the interference limit line is close to the boundary
line of the conjugate region of the worm pair, and the hazard of
curvature interference evident increases. Generally, a smaller value of
the technological crossing angle within its available value range can
completely avoid the occurrence of the curvature interference.