铝钢双金属构件触变软芯复合锻造成形数值模拟及验证

Simulation and Verification for Thixotropic-core Compound Forging Formation of Aluminum-steel Bimetal Components

提出了触变软芯复合锻造成形技术,以某型铝钢双金属标准圆柱直齿轮为成形对象,通过有限元模拟研究了不同钢质层初始壁厚以及初始温度时的双金属协调变形行为。结果表明,铝/钢协调变形行为主要受钢质层初始壁厚与半径的比值影响;铝/钢在协调变形过程中形成机械互锁,钢质层齿顶壁厚增加,齿根壁厚明显减薄,成为开裂危险区;提高钢质层温度有助于改善其流动性,但温度过高时,铝芯接触到钢质层后被快速加热,流动应力大幅降低而流动紊乱。钢管初始温度为1 100℃、初始壁厚为4 mm时,齿轮成形品质较好。基于仿真分析设计了成形试验,获得了成形品质良好的铝钢双金属齿轮,证明触变软芯复合锻造技术可实现复杂铝钢双金属构件近净成形。

A thixotropic-core compound forging technology was proposed for forming an aluminum-steel bimetal standard cylinder spur gear. The effects of initial temperature and thickness of the steel shell on bimetal synchronous deformation mechanism of the gear were investigated by finite element method(FEM). The results indicate that the synchronous deformation behavior of the billets is determined by the ratio of thickness to radius of the steel shell. During the forming process, reliable mechanical interlock is formed between the aluminum alloy core and steel shell. In the bimetal gear, the thickness at the tooth tips of steel layer is increased and that at tooth roots is decreased, thus forming cracking dangerous zone. It is helpful to improve the fluidity of steel shell with increasing steel shell temperature. However, the aluminum core suffers anoverly heating when contacting steel layer at higher temperature, leading to the sharply decrease of the flow stress and disorders. When the initial thickness and temperature of steel shell were 4 mm and 1 100 ℃, respectively, the synchronous deformation quality is desirable. In conclusion, the forming dies were designed and the experiment was carried out based on the simulated analysis. A well-formed bimetal gear was obtained, demonstrating that the thixotropic-core compound forging technology was a satisfactory method for producing complex aluminum-steel bimetal components.