Layer-by-layer surface laser cleaning method for 3D metal printing

The invention discloses a layer-by-layer surface laser cleaning method for 3D metal printing. The cleaning method comprises the steps that 1, an auxiliary laser generator is arranged in a 3D printer,a laser conversion device is provided, the laser conversion device is used for converting the light spots of auxiliary laser beams emitted by the auxiliary laser generator into linear light spots, wherein the auxiliary laser generator emits lasers used for evaporating impurities; 2, the linear light spots are used for scanning and cleaning the surface of a base of the 3D printer; 3, after powder of the first layer is laid, main lasers starts to scan and machine the laid powder, and under the condition that the scanning position of the light spots of the auxiliary lasers does not exceed the position of the scanning light spots of the 3D printing lasers, scanning and cleaning are carried out on the part which is printed out; and 4, after the first layer is formed and cleaned, forming and cleaning of the next layer c