Research On Laser Surface Micro-texturing-the New Complex Processing Technology Which Improves Noticeably The Lubrication And Wear-resistance Of Friction Units

As is well known, various friction units exist in ordinary mechanical systems. Friction of these units influences the performance and efficiency and even results in failure of the mechanical systems. Therefore how to improve lubrication and wear-resistance of friction units by laser surface micro-texturing technology according to the theory of lubrication is currently a hot issue for research. Being both theoretically and practically promising, it is widely concerned in the applied engineering field home and abroad.Researching on the friction units system of the internal combustion engine cylinder liner/piston ring—one of the most typical and complex friction units, this paper gives a systemic survey of worldwide researches on friction, lubrication and wear resistance of the cylinder liner/piston ring friction units, and briefly introduces the recent research development in the surface engineering technology, then on this basis presents a new complex processing technology which improves lubrication and wear-resistance of friction units by laser surface micro-texturing technology according to the theory of lubrication. This paper also illustrates in depth the interaction mechanism between the laser and the substance, and by using the software ANSYS it offers a numerical simulation of both the temperature field distribution and vaporization removal of the grey cast iron processed with pulsed laser. Systemic experimental studies on laser micro-machining have been done, a new laser processing crafts of "single pulse at a time, repeat at intervals" has been presented by our research group and a special equipment for cylinder liner laser micro-machining is successfully made. In addition, the lubricating theoretical model of the cylinder liner/piston ring which has micro geometric surface structure is developed. By using the multi-grid method to solve the theory model, the cylinder liner/piston ring surface micro geometry shape parameters are preliminarily obtained, and their influence rules on the lubrication oil thickness and the pressure are acquired as well. To investigate the lubrication and wear-resisting behavior and effects of the laser micro-textured friction units on the work piece surface, systemic fast attrition simulation tests have been carried out with "the cylinder liner/piston ring attrition tester of reciprocating engine". Finally, the laser micro-textured cylinder liners were mounted on the 4L88 diesel engine in Changzhou Diesel Engine Group and the CA6DF2-26 diesel engine in Wuxi Diesel Engine Works for bench tests to test their overall properties.Conclusions obtained are as follows: the complex processing technology of laser surface micro-texturing is a new micro-machining technology. It is based on the theory of friction and the needs of lubrication, and it contributes to both the hydrodynamic lubrication on the surface friction units and the optimized mechanical property distribution of the surface substance. High micro-processed quality on metal surfaces is obtained with the new laser micro-processing crafts of "single pulse at a time, repeat at intervals" and the aid of some special technical crafts as well as optimal combination of laser technical parameters. On the laser micro-textured friction units surface, friction coefficient has decreased remarkably and anti-scuffing ability has been improved greatly, and the wear-resisting behavior has been enhanced about 3~4 times compared with the un-textured specimens. The laser micro-textured cylinder liner mounted on the 4L88 diesel engine showed: the oil consumption reduced by 14.9%～43.5%, with the average reduction being 30.22%. The brake specific emission for HC decreased by 9.62 %, and the The brake specific emission for particles decreased by 18.87%. In standard working conditions, the fuel consumption reduced 4.72%. The plunger air leakage rate decreased by 30% in standard working condition, and in maximum torque working condition it decreased by 20%. The laser micro-textured cylinder liner mounted on the CA6DF2-26 diesel engine showed: the oil consumption reduced by 53%, and the air leakage rate decreased by 33.3 %～50%.