The Research On Surface Roughness And Warping Displacements Of Thin Wall Parts By Laser Additive Manufacturing

Laser additive manufacturing is a new rapid prototyping technology,which has a series of advantages such as short cycle,high degree of freedom and complex parts.So it is widely used in many fields.However,there are still some key problems in laser additive manufacturing process,such as surface roughness and warping deformation.Therefore,it is of great significance to study the surface roughness and deformation of laser additive parts.Based on the characteristics of laser additive manufacturing technology,the effects of different process parameters(such as scanning speed,laser power,laser pulse period,and different stepped pulses)on the roughness of laser additive manufacturing were studied from the aspects of the width,height and roughness of single multilayer thin-walled parts.The results show that adjusting laser power and scanning speed can effectively improve the surface roughness,but pulsed laser can improve the surface roughness of the formed parts more effectively than continuous laser,and the roughness Ra reaches 8.43?m when the peak laser power is 600 W and the pulse cycle is 40 ms.Moreover,when the stepped pulse of700W/15 ms and 60W/25 ms is used,the roughness reaches 8.2?m.The effect of different scanning path,scanning speed,laser power,laser pulse period,pulse duty cycle,pulse energy distribution,and stepped pulse on the warping displacements during laser additive fabrication was studied by a single experimental variable.The results shows that:(1)the two-way scanning path and interlayer stay are beneficial to reduce the warping displacements of the substrate;(2)the smaller the laser power and the faster the scanning speed,the better it is to reduce the warping displacements of the substrate.(3)the pulsed laser can effectively reduce the warp displacements of the substrate.Pulse width,duty cycle,pulse energy distribution and pulse waveform have certain regulation effects on the reduction of warping displacements,and the pluse width and duty ratio have remarkable effect on reducing warping displacements.