我国自五十年代以来生产的钢齿不密封滚动轴承三牙轮普通石油钻头,钻时短、进尺低,不能满足石油工业飞速发展的要求。普通钻头牙爪部件采用20CrMo钢制造,牙爪轴颈部位经液体渗碳及二次淬火处理。据统计这类钻头的失效,80%以上是由于牙爪轴颈受力面部位先期损坏所致。因此,发展了新型密封滚动轴承钻头,除了改进钻头的结构设计以外,还须提高牙爪轴承部位的使用寿命。资料说明20CrNiMo钢(相当于SAE8720钢)的渗碳性能和淬透性优于20CrMo钢,其综合力学性能较好,可以作为牙爪部件用钢。对于承受带有冲击的接触疲劳负荷的渗碳轴承零件,在交变接触应力作用下受力面产生麻点剥落是导至轴承失效的主要原因。资料认为带有冲击的较重的接触疲劳负荷(接触应力σ=250～300公斤/毫米~2)的石油钻头轴承 China’s steel gear produced since the 1950s does not seal the ordinary three-cone roller bearing oil drill bit, drill short, low footage, can not meet the rapid development of the oil industry requirements. Ordinary drill tooth claw parts made of 20CrMo steel, tooth claw neck by liquid carburizing and secondary quenching. According to statistics, the failure of such drill bit, more than 80% due to premature damage to the tooth claw shaft neck area. Therefore, the development of a new sealed roller bearing bit, in addition to improving the structural design of the bit, the tooth claw bearing parts must also improve the service life. Data Description 20CrNiMo steel (equivalent to SAE8720 steel) carburizing performance and hardenability better than 20CrMo steel, its comprehensive mechanical properties are better, can be used as claw parts steel. For carburized bearing parts with impact fatigue loads, pitting spalling on the bearing surface under alternating contact stresses is the main cause of bearing failure. It is considered that the oil drill bearing with a heavy impact fatigue load (contact stress σ = 250 to 300 kg / mm 2)