The fly cutter machining method is a technique used on gear hobbing machines or milling machines. It employs one or more cutting tools (called fly cutters) mounted on a tool holder to replace the worm gear hob, machining the worm gear through generating motion. Essentially, the fly cutter is a single-tooth (or the number of teeth equals the number of worm threads) worm gear hob, which is convenient to design, simple to manufacture, and low in cost.
During machining, the worm gear workpiece is horizontally mounted on the worktable. The fly cutter is mounted on the tangential tool post of the machine tool. The cross-sectional shape and dimensions of its cutting teeth are the same as those of the worm gear hob teeth, and the rake face and the centerline of the tool holder form the lead angle of the worm. During the cutting process, in addition to the hobbing rotation (tooth indexing motion) of the tool and workpiece, the tool also performs a tangential feed motion, thus continuously generating the tooth profile. This method is best performed on a gear hobbing machine with a tangential tool post.
The fly cutter machining method is particularly suitable for single-piece, small-batch production, as well as the machining of large-module, special-specification, or modified worm gears. It effectively solves the problems of uneconomical manufacturing and long production cycles of worm gear hobs. Its advantages include simple tool structure, ease of manufacturing, and low cost. Its disadvantages include lower production efficiency and generally poor machining accuracy and surface roughness.
In recent years, the fly cutter machining method has been extended to the machining research of new transmission components (such as worm gears). This research proposes a method for designing the fly cutter cutting edge based on the tooth profile of the Archimedean worm shaft section, and develops two implementation methods for fly cutter axial feed and radial feed. The feasibility of this method has been verified through simulation and experiments.
