Meshing limit line of Niemann face wormgear drive

The main work of this paper is to systematically establish the calculation methodology for the meshing limit line of Niemann face wormgear drive. The nonlinear equations for determining the meshing limit points are constructed and solved successfully. Plotting the meshing limit lines into the axial-section of the worm can intuitively reflect the position relationship between the limit lines and the worm tooth surface. The characteristics of the meshing limit line are comprehensively investigated. Mathematical results show that there are two meshing limit lines on each flank of the single-thread worm in Niemann face wormgear drive. These limit lines are spiral along the worm axis. Under general parameter matching, the meshing limit lines do not enter the worm tooth surface. The worm can maintain a long working length. The intersection between the addendum and the inner end of the worm may be potentially attacked by the meshing limit line. Based on the understanding of the meshing limit line, the critical axial installation site of the worm is derived. It makes that the Niemann wormgear drive can obtain better performance by using a smaller contour.