s continued Nominal power ratings PN kW type H o B2-VV-13-D Bevel-helical gear boxes B2

Flender/Flender Gear Units/Bevel-helical gear boxes B2

machining processes. The method is also limited because of the maximum possible hypoid offset and the choice of spiral angle. The only process used for hard nishing is lapping. Zyklomet This is special form of the Zyklo-Palloid method, in which the tooth slots of the wheel are plunge cut with face hobbing cutter head, and only the pinion is generated using cutter which is inclined or tilted relative to the pitch plane (see Sect. 3.2.1 ). Lengthwise crowning is provided solely by the wheel while prole crowning is produced using spherical blade proles. For the pinion, onlyone-part cutters are used while the wheel cutter is made of two parts and in somecases tted with larger number of blade groups. With one-part cutters, thelengthwise crowned wheel has to be manufactured in single-ank process. Forthis purpose special bevel gear cutting machines with two cutters on their rollingcradles have been developed. This method is applied very rarely nowadays. -method This is face hobbing method working with two-ank cuts. The tooth trace is an elongated epicycloid and tooth depth is constant. Both the pinion and thewheel are generated. The special feature of the -method is that the epicycloid lengthwise curvature at the mean point corresponds to that of an involute, also termed involute case orrectangular case (see Sect. 3.4.4 ). This makes it possible to produce lengthwise crowning using combination of face hobbing cutters withdifferent resulting angles where inner and outer blades immediately follow eachother on the cutter face. drawback, however, is that the spiral angle of the gearthen depends on the mean cone distance and the selected cutter diameter, and can nolonger be chosen at will. Therefore, it is not possible to produce every spiral angleon gear set with the available cutters, which have three blades per blade group (inner, middle and outer). Prole crowning is achieved using spherical blade pro- les. This method is used only to very limited extent now. Spiro