Liyang Dong

An NC rough turning method of an enveloping toroidal worm

Due to the inefficiency of the grinding method, the enveloping toroidal worm is usually pre-processed using the turning method of the hindley worm. The difference between the turning and the grinding method leads to the great and inhomogeneous allowance during the subsequent grinding process of the enveloping worm. A new rough turning method was presented based on discretization of the spiral surfaces of the worm. The spiral surface was cut by the tool tips of a turning tool along the discrete points calculated from the mathematical model. The grinding allowance was equalized and the grinding time decreased significantly. The spiral groove of the worm was cut layer by layer in the tangential and radial directions of the rotation of the turning tool tip. The distance between the rotation axis of the tool and that of the worm was changed gradually so that the entire height of the tooth could be cut. A series of rotating angles of the worm and the turning tool were determined for programming an NC turning machine tool. The generation process of a plane enveloping toroidal worm was simulated in an numerically controlled simulation system. The grinding allowance was obtained and analysed. Trial manufacturing was performed and the results showed that the grinding allowance could be equalized and the manufacturing efficiency could be increased.