A novel generating machining process for screw-rotors using an internal-cylindrical skiving cutter on a new CNC skiving machine

To reduce machining time and improve accuracy for producing screw rotors, this study proposes a generating machining process using an internal-cylindrical skiving cutter on a new CNC skiving machine. An internal-barrel rotor is first generated based on a conjugation relationship with a male/female rotor. Then, the cutting edges of the internal-cylindrical skiving cutter are defined by the intersection curves between the rake plane and the barrel rotor surface. A geometrical analysis of the clearance angle allows adjustment of the relative position between the cylindrical cutter and the skived rotor on the cutter's axis. Furthermore, a general model for the skiving process is presented. The result shows that the normal deviations on the skived screw rotors are very close to zero. In addition, a new CNC skiving machine is proposed to perform the cutting process when considering the influence of feed rate. Accordingly, the surface morphology of the skived screw rotor is in the form of micro-size waves arranged in a diagonal structure. Finally, the skived screws surface with a predefined grinding stock is achieved by modifying the cutter geometric.