A fewer-axis dressing method for accurate and flexible worm dressing in face gear grinding

Grinding worms are essential for achieving high efficiency and pitch precision in face gear machining, but their complex tooth flank geometry presents dressing challenges. Traditional dressing methods using form or double-cone dressing wheels suffer from limitations, including theoretical errors caused by tilting the worm lead angle, accuracy issues with swiveling and tilting axes, complex machine kinematics, and difficulty in dressing non-involute worm profiles. This study proposes a fewer-axis dressing method using a circular-section dressing wheel and an auxiliary nominal shaper to avoid the need for tilting and swiveling motions. The method employs only three machine axes to provide rotational, radial and axial movements for the worm during dressing. Machine kinematics and an equidistant path distribution approach are developed to ensure precise and efficient dressing. Uniform cutter marks on worm flanks with maximum deviations of -0.89 μm and a sum of squared errors of 17.7 μm² indicate no significant theoretical error. Dressing simulation shows that the main working area of the worm flanks achieves high accuracy, and deviations at worm roots are negligible as they do not affect face gear grinding. A dressing experiment of the worm is performed based on the simulation-verified dressing kinematics and step size; the maximum value of flank deviation is 16.2 μm. This method offers a precise and practical solution for worm dressing in face gear grinding applications.