<p>Curvature interference is a common phenomenon encountered during the machining of gear tooth surfaces. The occurrence of interference can deteriorate the machined quality of the tooth surfaces and reduce transmission performance. To determine and avoid tooth surface interference, a calculation method for the curvature interference limit function, which is based on principal frame projection, Rodriguez’s rotation formula, and Lagrange’s identity, is proposed in this paper. By the gear meshing theory, a univariate nonlinear equation and two parametric calculation formulas for determining these interference boundary points are derived. Via a numerical case, the curvature interference characteristic of the offset worm pair is studied, and it is proved that the convex surface of the worm gear hardly interferes and its concave surface has a high risk of interference. Given this, the influence of three main process parameters of the grinding wheel on the interference of the concave surface is investigated. The results show that all three process parameters can reduce the risk of interference, among which the influence of the process crossing angle is the most notable.</p>