镁合金板料摩擦热渐进成形机理及技术研究

Currently, for the lower formability of magnesium alloy at room temperature, in order to meet manufacturing needs of the products in aerospace, car, appliances and communications, the new manufacturing method of the sheet metal heating by friction heat is presented on the basis of the achievements of warm incremental forming of magnesium alloy AZ31 by heating.By theoretical analysis, experimental study and numerical simulation, the research is made on the principle of friction heat production,material plastic flow acts and the constitutive model, lubrication between sheet metal and forming tool and characterization of forming defects, sheet metal incremental forming process control,the deformation organization analysis, the technology optimization and numerical simulation in sheet metal incremental forming process by friction hot forming conditions; material plastic flow law is revealed, the plastic deformation micro-organization and defects evolution law is stated by coupled role between temperature field and force field, the effect of coupled role of multi-field on plastic deformation mechanism is revealed, the control methods of parts shape on the basis of error compensation feedback are established. The manufacturing core technology on difficult deformation light alloy (such as magnesium alloy) sheet metal parts with high performance, high efficiency and high-quality is supplied for aerospace, automotive, home appliances and communications, the theory system is perfected and established on magnesium alloy friction hot incremental forming manufacturing of complex sheet metal parts, the gratifying achievements of original research is achieved.

针对镁合金室温下成形性能差的问题，在目前利用额外热源加热的热渐进成形镁合金等板料零件制造取得的成果基础上，围绕我国航空航天、汽车和家电等新产品的制造需求，提出利用旋转成形工具与板料产生摩擦热来局部加热镁合金坯料而制造镁合金零件的新技术。通过理论分析、实验研究和数值模拟等方法，研究摩擦热产生原理，摩擦热条件下的镁合金板料塑性流动行为及本构模型，板料与成形工具间的润滑，板料渐进成形控制，成形组织分析以及渐进成形过程数值模拟及工艺优化，揭示摩擦热条件下材料塑性流动规律，阐明温度场和力场耦合作用下的塑性变形微观组织变化和缺陷演变规律，揭示多场耦合作用对塑性变形机制的影响，建立基于误差补偿反馈的零件外形调控方法。为我国航空航天、汽车、家电、通讯等产业中的镁合金等轻合金板料零件的高性能、高效率和高品质制造提供核心技术，完善并建立镁合金等板料零件摩擦热渐进成形制造技术的理论体系，取得原创性的研究成果。

目前一般采用额外加热来解决镁合金室温成形性能差的问题，但是需要增加隔热和冷却系统，设备复杂、成本高。为此，提出利用摩擦热进行板料渐进成形的新方法。它能实现加载、加热及成形一体化。通过理论分析、实验研究和数值模拟等方法，研究了摩擦热渐进成形系统和理论，材料塑性流动行为、本构模型及成形极限，成形模具与板料间的摩擦热产生规律及润滑方法，起皱、破裂和回弹等成形缺陷的机理，板料渐进成形影响因素和过程控制，以及板料渐进成形过程数值模拟及工艺优化，揭示了摩擦热条件下材料塑性流动规律，阐明了摩擦热作用下的应力、应变分布规律和成形极限规律，揭示了多场耦合作用对塑性变形机制的影响，阐明温度场和力场耦合作用下的微观组织和缺陷演变规律，建立摩擦热渐进成形理论和方法。.研究结果表明成形工具转速越高产生的摩擦热温度就越大，材料的成形能力显著增长，但是温度太高由于产生搅拌而不能成形。因此，通过工具旋转所产生的摩擦热使材料成形性能提高。在一定的旋转速度、进给速度和压下量条件下，AZ31B 镁合金薄板可以实现单点渐进成形，为解决镁合金室温难成形问题提供了一种新方法。渐进成形是加工硬化、静态再结晶和动态再结晶的复杂过程，微观组织由粗细不一混合晶粒组成，决定于板料的成形温度和成形时间。.对掌握镁合金板料成形规律，完善镁合金板料成形理论，满足镁合金板料零件大批量生产需要等有重要意义。