The invention relates to an annular worm digit-control machine which can simulate central distance, wherein it comprises four coupled coordinate motions that the main axle has a rotation A around its axle (parallel to Z); the work bench has the translate motions X, Z which are vertical and in horizontal plane, and the tool bench has the rotation Y around its axle 00 (vertical to the XZ plane); the work bench rotates with the transmission ratio i=A/Y with the main axle, and couples with X, Z, and rotates around the simulated round center (the round center of annular worm) to use the machine with small central distance to process the concave and convex annular worms with large central distance, with low cost and compact structure. |