Formation and modeling of vertical Outside wall of compoents inclining inward in laser solid forming

The vertical outside wall is prone to incline inward in laser solid forming, which will deteriorate the dimension precision and processing stability. For solving this problem, samples with different amount of deposited layers were prepared and the variation of boundary single-track clad shape and formation of vertical outside wall inclining inward were investigated. Based on the method of constructing cross-section profile of the single-track clad by height of powders accumulated in molten pool, an analytical model was developed to describe the evolution of vertical outside wall during multilayer superimposition. A series of vertical outside walls under different width/height ratios and critical defocus distance were constructed with this model to investigate their influence. Results indicate that the deposited single-track clad will influence the formation of single-track clad under depositing. Due to the arc-like cross-section profile of single-track clad, the molten pool will shrink inward, which leads the outer edge of boundary single-track clad to shrink inward then the vertical outside wall to incline inward. However, this incline will decrease with the increase of deposited height. For the initial single-track clad with fixed width, decreasing critical defocus distance can decrease the inward incline but increase the offset from the preset dimension. The width/height ratio almost has no effect on outside wall.