5AXIS CNC MANUFACTURING OF EDM BEVEL GEAR ELECTRODES

抄録

Electro-discharge manufacturing, or EDM, is a common process used to create the punches required in the manufacturing of small size powder-metal (PM) bevel gears.
For small module straight, Coniflex, or spiral-bevel gears, 5Axis CNC manufacturing of EDM electrodes using End Mill and Ball Mill tools offers flexibility, reduced tool inventory, and especially the use of only one CNC machine as opposed to several dedicated gear-cutting machines.
This paper presents an approach to 5Axis CNC milling of straight-bevel, Coniflex and spiral-bevel gears with modules in the 1 to 1.5 mm range. The gears are made of copper and are used as electrodes in EDM to produce punches for PM manufacturing.
The basic mathematical approach to CNC gear manufacturing with End Mill or Ball Mill tools is presented, keeping in mind that EDM electrodes must be smaller than the final tooth in order to allow clearance in the EDM machine when creating the punch mold.
Examples illustrate the excellent results that are achieved and some difficulties linked to manufacturing gears of small tooth sizes.