Development and present situation of scraping machining of hard tooth surface of spiral bevel gear abroad

Since the 1960s, Japan, the former Soviet Union and some other countries have successively carried out the development and research of hard tooth surface scraping technology. Professor Xiangpu Zhengren of Japan and others have carried out a series of experimental studies on cemented carbide materials for hard tooth surface hobbing, the design, manufacture and use of cutting tools, hobbing conditions and so on. In the early 1970s, Azmi company of Japan obtained the patent of carbide scraping hob and officially put into production. Other factories have also manufactured this hob for the market. The scraping technology of hard tooth surface was rapidly popularized in Japan, quickly introduced into Europe and America and widely used. The efficiency of this finishing process can be improved by 3-5 times compared with the traditional gear grinding process, and the finishing cost of gear surface is reduced by more than half.

Sumitomo Electric Appliance Co., Ltd. of Japan adopts welding the blade pressed with cubic boron nitride sintered Sumitomo Electric Co., Ltd. of Japan uses the blade pressed with cubic boron nitride sintered product body welded to the general steel cutter head to manufacture the hard tooth surface milling cutter head. The large wheel is processed by forming method and the small wheel is processed by rolling cutting method. This processing method does not need to add new equipment, but only needs to install the hard tooth milling cutter head on an ordinary gear milling machine. The module of the processed gear is 7-21.75mm, the tooth surface hardness is hrc58-63, the accuracy reaches JS-1 (equivalent to China’s level 7 accuracy), the tooth surface roughness can reach ra1-2um, and the gear life is long.

Since the 1970s, Klingenberg company of Germany has adopted high-power gear plus method to eliminate the heat treatment deformation of gears. This method is to mechanically clamp a hard combined blade to the base of the cutter head to process the gear. The cutting tool adopts the front angle of the top edge of – 16 °, and a small chamfer is opened on the cutting edge to scrape the cycloidal bevel gear of hrc57-63. After machining, the tooth surface accuracy can reach din5, the tooth surface roughness can reach RA 0.625-1.25um, and the transmission power can reach 5000 kW.

The machine tool Department of Gleason company officially published the data on hard tooth surface machining in 1981. The company selects an ideal cemented carbide blade (the specific value of negative rake angle in axial and radial directions is not clear), welds it under the cutter head base, installs the cutter head base on hardense3 or tan-tru cutter head body, and uses no-641 and no-655 gear milling machines to finish milling the tooth surface of spiral bevel gear hardened to HRC58-62, The tooth surface accuracy reaches agma11-12 (equivalent to grade 6-7 of jb180-60 in China), and the roughness reaches ra0.14-0.5um.

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