基于可控表面微特征的冷锻摩擦微观机理及润滑改善方法研究

To meet the challenges from environmental protection issues，development of novel environmentally friendly manufacturing techniques or upgrading of existing environmental standards of advanced manufacturing technology has become a new trend in the development of automotive industry. Cold forging is one of the advanced manufacturing technologies with excellent economic benefit, but the phosphating plus soaping treatment process, which is usually used as a lubricating method in the mass production of cold forging, is definitely damage the environment by the acid mist and heavy metal slug producing in the process. Therefore, how to improve its environmental level and to promote its connotative development, already become an important issue which must be directly faced and urgently needed to be solved by both the academia and industry sides. Based on the basic theory of tribology, plasticity mechanic and surface science, system research works will be conducted in this study. Firstly, considering the effect of surface micro-features, the microscopic mechanism of contact friction between workpice and tooling in cold forging would be revealed, and the effect of surface topography of workpiece and tooling on the friction behavior would be investigated, and the evolution of surface topography after cold forging would also be analyzed. Secondly, a manufacture process that could be used to form controlled micro-feature on metal surface should be put forward, and a quantitative description method for this micro-feature should be proposed correspondingly, then a modified friction model would be established according to the effect of surface micro-feature on the friction. Thirdly, quantitative determination method for friction conditions in cold forging and sensitive testing device for lubrication effect in cold forging should be carefully designed and critically evaluated, based on this the evaluation system for the friction and lubrication in cold forging would be established, and the effect of surface micro-features on lubrication result would be investigated by using the evaluation system, then better lubricant and lubricating method could be selected. Finally, a combined environmentally friendly lubricating strategy which could replace or partly replace the phosphating plus soaping treatment would be obtained, with this the environmental level of cold forging industry would be improved and which could greatly benefit the automobile industry.

研发全新的环保型制造技术或提升现有先进制造技术的环保水平，已成为汽车装备制造业的发展新趋势；冷锻作为具有优异经济性的先进制造技术，提高其环保水平以促其内涵式发展，已成为学术界与工业界必须面临且迫切需要解决的重要问题。本项目拟开展系统研究，揭示基于表面微特征的冷锻成形接触摩擦的微观机理，探讨不同模具表面微特征与工件初始表面微特征对冷锻摩擦的影响规律，分析经冷锻变形后工件表面形貌的演化规律；形成一种金属表面可控微特征的加工方法，提出适用于表面微特征的定量描述方法，建立引入表面微特征参数的摩擦修正模型；形成冷锻成形摩擦条件的定量分析方法，设计并制造对冷锻润滑敏感的检测装置，建立冷锻摩擦与润滑的评价体系；分析表面微特征对冷锻润滑的影响效果，优选润滑剂与润滑方式，提出环境友好的替代或者部分替代传统磷皂化工艺的新型冷锻润滑策略与方法，提高冷锻工业生产的环保水平，更好地服务于我国汽车工业的宏观发展战略。

研发全新的环保型制造技术或提升现有先进制造技术的环保水平，已成为汽车装备制造业的发展新趋势；冷锻作为具有优异经济性的先进制造技术，提高其环保水平以促其内涵式发展，已成为学术界与工业界必须面临且迫切需要解决的重要问题。本项目主要开展了金属表面微特征的制造方法、基于表面微特征的冷锻成形摩擦微观机理、冷锻摩擦条件的定量测试方法、冷锻润滑效果的检测方法、环境友好的冷锻成形润滑策略，以及典型应用冷锻工艺案例等研究具体研究工作。提出了基于电子束抛光技术的模具表面微特征制造方法与基于类抛丸技术的坯料表面微特征制造方法，可以分别在模具和坯料表面进行表面微特征的可控加工，实现了大小为10-60微米、深度为5-15微米微特征制造；重点探讨了冷锻成形摩擦中的各向异性现象，分析了该现象的微观机理，并采样有限元模拟技术仿真了摩擦各向异性条件对冷锻成形过程的影响规律，为后续控制摩擦引导成形奠定了理论基础；发明了冷锻成形摩擦条件与润滑效果测试方法，与传统的圆环镦粗测试法相比，更为方便、快捷和准确，并获国际同行认可，设计并制造相应的测试装置，建立了冷锻摩擦与润滑的综合评价体系；提出了一种类抛丸滚涂工艺用于替代传统磷皂化工艺进行冷锻润滑处理，并在结合齿圈冷锻成形中得到应用，改善其生产过程的环保水平。为更好地开展本项目的应用研究，面向工程实际，针对传统剪切下料断面质量较差的问题，提出一种预剪剪切下料方法，利用预剪工序引导剪切下料，可以有效改善剪切下料质量；针对冷锻模具强度的问题，提出引入自增加理论并考虑热变形影响的组合凹模设计理论与方法，可以改善模具应力状态；针对复杂工字型零件难成形的问题，利用浮动模具结构引入积极摩擦效应，实现工字型锻件的冷锻成形。