抄録
A built-up hob for a screw-compressor rotor is proposed. The hob is composed of cutter blades and a hob head. The blade is cut out from a tempered planar plate of high speed tool steel by wire-cut electrodischarge machining (EDM). During the wire cutting process, the wire electrode has a fixed angle to ensure both the side and the end relief angle of the cutting edge, so that the rake face regrinding sharpens the cutting edge without changing the profile of the rake face. In other words, theoretically, the hob has no accuracy deterioration due to rake face regrinding. The formulae of rack tooth profile are derived from the female rotor tooth profile experssed by numerical formulae. Next, the fundamental helicoid of the hob the profile of the cutting edge of the blade are calculated. The hob was fabricated and the rotor hobbing was carried out.
