Roller Bit Spherical Floating Bearing Laser Research And Application Of Quenching Technology

Cone bit as the most important drilling tool, its performance will directly determine the merits of drilling efficiency and drilling cost, and thus determine the continuity of oil and gas resources exploitation. While bearing as one of the main parts of rock bit, which directly determines the length of life of roller cone bit. In the actual work process, the poor wear resistance, adhesion wear failure of bearing is one of the main constraints to cone drill life, but also pass a bearing rock breaking required hundreds kN bit pressure, and a greater impact load be born by bearing.In order to improve cone bit bearing wear and fatigue resistance, this article will traditional cylindrical outer surface of the sliding bearing was repaired edge into the sphere, and for the first time this advanced laser hardening of surface modification technology references to spherical floating sleeve bearing of rock bit and the laser hardening surface modification technology will be researched about spherical floating sleeve bearing in cone bit by combination with theory, finite element analysis and experimental, and spherical floating sleeve bearing laser hardening process parameters were optimized, the spherical floating sleeve bearing just just outside and tough inside. Through this study, to offer a new approach and new ideas in order to improve the wear and fatigue resistance of cone bit bearing, and then improve and stabilize the life of cone bit. The research results and the completion of the main work are as follows:(1) Based on literature research shows that the cone bit Bearing has the problems of poor wear resistance, failure to adhesive wear and withstand impact loads, and laser hardening technology has its unique advantages in improving the wear resistance and fatigue resistance aspects, This is the first laser hardening is refered to the spherical floating sleeve bearing in roller cone bit, pioneered a new method and idears about improve the wear and fatigue resistance of cone bit bearing.(2) Taking into account the work environment of cone bit bearing, this paper make 18CrNiMo7-6 steel as bearing material, and do carburizing treatment where is inner and outer surfaces of the bearing, and bearing numerical simulation of carburizing seen: the inner and outer bearing surface have about 0.8mm layer after the carburizing, and the carbon content has reached about 0.8. The bearing core nearly 1.5mm depth, carbon content less than 0.35, the minimum value of about 0.3, lay a solid foundation obtained just outside and tough inside about the spherical floating sleeve bearing after laser quenching.(3) In order to obtain the optimal laser quenching effect about spherical floating sleeve bearing, the laser hardening process parameters, namely the scanning speed V, the laser power P and the spot size D were compared optimization in this paper, and optimal scanning speed is 55mm/s, the best laser power be 1. lkw, and the optimum spot size be ?3.5mm were obtained by finite element analysis when the spherical floating sleeve bearing in cone bit conduct laser hardening.(4) The spherical floating sleeve bearing in roller bit were conducted laser quenching Under the optimal laser hardening process parameters, and we found that the phase transition zone center in bearing can achieve a peak temperature in less than 0.3s time,and the maximum heating rate was achieved 2.95 ×104?/s, and cooling is very fast, the maximum be 6.21 × 103?/s. In this rapid heating and cooling process, bearing phase transition region generated a lot of martensite and the volume fraction of martensite up to about 92% in the region from about 0.8mm inner and outer surfaces of the bearing. This makes the inner and outer surfaces of the spherical floating sleeve bearing hardened layer depth of about 0.83mm, and hardness is attained833.454HV, while the thickness have about 1.5mm in bearing core, and its hardness values are approximately around the following200HV, not only improve the wear resistance, but also to achieve a just inside the outer tough about spherical floating sleeve bearing. At the same time, bearing phase transition zone after laser hardening to the main stress, and tensile stress in the heat affected zone mainly, it explained that bearing will help to improve their resistance to fatigue by the laser hardening. In addition, the results of numerical simulation of bearings by laser hardening were compared with conventional quenching, and the analysis shows that:the effect of laser quenching to spherical floating sleeve bearing is superior to conventional quenching, not only improves the wear of the spherical floating sleeve bearing, but also realizes the outer just inside the tough of the bearing, both wear-resistant and can withstand a certain impact loads during operation.(5) In this paper, the spherical floating sleeve bearing was designed, manufactured, and conducted laser hardening field test, and the hardness and metallographic analysis of spherical floating sleeve bearing after laser quenching shows that:The spherical floating sleeve bearing were conducted laser quenching under the optimal laser hardening process parameters, there is no melting phenomenon; There are acicular martensite approximately 0.9mm depth in the inner and outer surfaces of the bearing; Experimentally measured simultaneously the maximum hardness was reached bearing 837.48HV, and inner and outer surfaces of the hardened layer depth reached about 0.9mm, while bearing core section has a hardness value of about 1.8mm or so in about 200HV, it reached the effect of just outside and tough inside and we can found that the same trend, fit better after comparion the experimental with modeled, but also to verify the correctness of numerical simulation methods to optimize the process parameters of laser hardening results.