铝合金环形座锻件等温精密成形工艺研究

Study on isothermal precision forging process of an aluminum alloy ring seat

为选择合适的铝合金环形座锻件等温精密成形工艺,防止各种缺陷的发生,并使其获得合格的力学性能和抗应力腐蚀性能,采用有限元方法模拟了环形座锻件的成形过程。分析了成形时的金属流动规律,并通过预锻制坯和三次模锻工艺形成了外形完美、性能合格的高质量铝合金环形座锻件。结果表明,环形座外环壁表面处易受剧烈剪切变形而产生粗晶缺陷,因此应适当减小该处的坯料体积。坯料设计时应精确计算体积,避免多余金属过多引起终锻后期的大量金属外排,从而防止外环壁折叠缺陷的产生。通过采用多次模锻的方法在每次模锻后去除多余飞边和连皮,既可以减小下一阶段模锻成形过程中飞边桥部的阻力,降低模压力,又可以防止终锻时大量金属外排造成的折叠缺陷。

In order to choose an appropriate process for the isothermal precision forging of an aluminum alloy ring seat, prevent the occurrence of various defects and make the alloy possess qualified mechanical properties as well as resistance to stress corrosion, the finite element method （FEM） was adopted to simulate the forming process of the ring seat forging. The laws of metal flow were analyzed and high-quality aluminum alloy forging of the ring seat with perfect shape and appropriate performance were obtained by combining preforging with three times of die forging. The results show that severe shear deformation is easy to occur on the wall surface of the outer ring of the ring seat, which shall result in the coarse-grained defect, so the billet volume in the zone should be decreased properly. Billet volume should be calculated accurately in the process of billet design so as to avoid the outflow of plenty of metal caused by the excess metal in the late stage of final forging, which can avoid the folding defect in the wall of outer ring. By means of multiple die forging, excess metal in flash and wad is removed after each die forging step, which can not only reduce the resistance of the flash bridge in the next stage of die forging to lessen the forging force, but also prevent the folding defect caused by overabundance metal in the final die forging.