The forming method of gear wheel machining was put forward by Gleason company in the late 1930s. It is mainly used to process gear wheels in spiral bevel gear pairs and hypoid gear pairs of automotive rear axle, and its production efficiency is 4-5 times higher than that of the generation method. When using this method to process gears, first rough cut grooves on the gear wheel rough cutting machine, and then fine draw on the gear wheel fine cutting machine. The fine drawing cutter head is divided into three parts: semi fine cutting, fine cutting and indexing.
When gear drawing is used, the cutting allowance on both sides of the tooth groove on the gear blank should be evenly distributed. The gear blank enters the full tooth deep cutting position at the beginning of the tooth drawing machining. The cutter head rotates slowly around its axis, and the cutting edges on both sides of the cutter tooth are processed at the same time. After the cutter head rotates for one week, the fine drawing machining of a tooth groove is completed. The gear blank repeats the above gear drawing process after graduation. Gleason company calls this gear drawing method as single cycle method. The single cycle method is very suitable for mass production of spiral bevel gear wheels and hypoid gear wheels with transmission ratios greater than 2.5. For small batch production, Gleason invented a method of machining on universal gear milling machine, which can process the forming method gear wheel from blank to finished product in one clamping. This gear drawing method is called rough cutting and fine drawing method. During rough cutting and fine drawing machining, the workpiece moves to the cutter head under the action of the feed cam, and the cutter head rotates for rough cutting. At this time, the fine drawing blade will not participate in cutting because it is slightly lower than the rough cutting blade. When the rough cutting process is completed, the workpiece is fed to the full tooth depth of the fine cutting, and the cutter head changes from the rough cutting speed to the fine drawing speed. When two fine drawing blades pass through the tooth slots and finish the fine drawing task, the workpiece quickly exits for indexing, and then starts the cycle of cutting the second tooth.
Around 1958, Gleason company proposed spiral forming method based on forming method and designed and manufactured No.112 precision cutting machine. In the spiral forming method, the axis of the cutter head is perpendicular to the cone of the gear wheel surface during the gear tooth drawing processing. When the blade is pulled from the inner end of the gear tooth to the outer end, only one blade is allowed to work, and an axial feed motion is given to the cutter head. In this way, it can not only ensure that the contraction teeth required by the gear wheel are processed, but also ensure that the axis of the gear wheel cutter head is parallel to the axis of the geat pinion cutter head.