Research And Application Of Heat Treatment Technology For Bearing Set Of Cone Bit

In the process of drilling, the operating performance quality of the roller bit, which is one of the most main broken crag tool, directly influence the well drilling quality, well drilling efficiency and well drilling cost. As human demand for oil and gas resources become increasingly big, people have to turn to worse natural environment, such as offshore, desert and plateau etc. For the difficulty of drilling is increasingly fierce, the performance of roller bit is put forward higher requirements. So, improving the service life of the roller bit become one of the problems to be sloved badly in broken rock bit field at home and abroad.In order to improve wear resistance of the rock bit bearing, tooth claw journal surface of normal rock bit is fased on wear-resistant alloy. But under the condition of high speed, due to the bearing calorific value and the surfacing welding defects on the surface, the failure of bearing is easy to caused by adhesive wear. In order to slove this problem, a bearing bushing of sliding bearing designed in this article, using mechanical design, material science, tribology and computer simulation technology, adopting the method of combination of theoretical and experimental research on bearing sleeve carburizing and quenching process and coating technology, which has provided a new of think, a new method and a new technology to design bearing of rock bit, to further promote the development of rock bit technology in China. Paper’s main work is as follows:1) The failure analysis of the roller bit. By collecting domestic and foreign literature about roller bit bearing and dissecting the failure bit in the field, we know most of rock bit are indicated by adhesive-wear failure of the bearing. In order to slove this problem, a bearing bushing of sliding bearing designed in this article.2) Numerical simulation on carburizing and quenching process of bearing sleeve. Based on the theory of Fick’s law and heatrware, SYSWELD software is used to numerical simulation on carburizing and quenching process of bearing sleeve. Through the computer simulation analysis, we know under the condition of outside surface(D5) for carburizing, diffusion conefficient of1.5e-6m2/s,940℃strong infiltration(carbon pontential)29700s,840℃diffusion(carbon pontential)6300s, the carburizing effect of bearing sleeve is the best. After quenching hardness value of bearing bushing declines gradually from outside surface to inside surface, at the same time, a comparison of simulated hardness value and measured of bearing bushing shows good agreement.3) Study on the performance of TiN/TiAIN coating. The performance of hardness, abrasion, friction conefficient and substrate of TiN/TiAIN coating is tested. The results show that these performance parameters of TiN/TiAIN coating can meet the commercial standards. Especially, when TiN/TiAIN coating paired with silver, its friction conefficient is about0.06, equivalent to1/10of friction conefficient of TiN/TiAlN coating paired with steel.4) Comprehensive bench test and field test of rock bit. A TiN/TiAIN coating of bearing bushing of sliding bearing of rock bit is made to operate comprehensive bench test, net drilling time of rock bit is95h, significantly higher than the working time(80h) of average rock bit. In order to further verify the effect of drilling, under the same tested condition of field drilling its paired with a bit factory of rock bit, the results prove it is better than a bit factory of rock bit in the overall quality.