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金属熔积直接成形过程不均匀的加热和冷却收缩过程使得制件内残留有较大的应力,这将引起制件发生大的变形甚至裂纹。制件内的应力积累与熔积过程的热循环和热积累有着密切的关系。本文建立了三维有限元熔积成形的模型来分析不同熔积轨迹下制件温度、应力变化和制件完全冷却后的应力分布。结果表明,与同向轨迹相比,异向轨迹与分段轨迹熔积直接成形均能降低制件内部的热积累和冷却过程不均匀的收缩,从而降低了残余应力。
Inconsistent heating and cooling shrinkage during the direct metal forming process cause large residual stress in the workpiece, which will cause large deformation and even cracks in the workpiece. The stress accumulation in the workpiece is closely related to the thermal cycle and heat accumulation in the melting process. In this paper, a three-dimensional finite element model of the hydroforming was established to analyze the temperature and stress changes of the workpiece under different deposition trajectories and the stress distribution after the workpiece was completely cooled. The results show that, compared with the same trajectory, the direct forming of dissimilar and segmented trajectory can reduce the internal heat accumulation and the non-uniform cooling of the cooling process, thus reducing the residual stress.