Study On Additive-Subtractive Hybrid Manufacturing And Surface Coating Process Of Powder Material

Selective laser forming is an important part of rapid prototyping technology because of its wide range of raw materials,simple manufacturing process and fast processing speed.However,due to the influence of material particle size,laser line width and principle of discretization,the dimensional accuracy and surface quality of the products are not ideal.Therefore,in this paper,combined with the advantages of selective laser forming technology and multi axis NC machining technology,a multi axis Additive-Subtractive Hybrid Manufacturing(ASHM)equipment for powder materials is designed,and 70 ~ 140 mesh coated pearl sand is selected as the forming material to explore the improvement effect of the hybrid manufacturing method and surface coating process on the appearance quality of products,the main contents and conclusions of this paper are as follows:(1)A set of hybrid manufacturing equipment for powder material is designed,which can complete the composite forming of powder material by in-situ processing.Through the main and slave collaborative motion control system,the signal communication between each module can be realized;(2)This paper presents a new method for data processing of ASHM,which can directly obtain the contour and internal filling track of parts through the secondary development of Solid Works.Not only the data accuracy is improved,but also the data file size is reduced by 70%,which effectively improves the efficiency of data acquisition and reduces the precision loss in the process of format conversion;(3)Under the process conditions of 0.3mm layer thickness and laser energy density of 0.139J/mm2,the average size deviation of about 0.3mm and a maximum size deviation of about 0.82 mm.The surface roughness measurement results are not evenly distributed under the combined influence of step effect and secondary sintering,mainly within the range of Ra50?m to Ra100?m.Composite parallel machining strategy and five-axis linkage machining strategy can realize the contour reduction machining of complex surface and complex structure,effectively solve the problem of step effect and secondary sintering in the process of additive,and control the average size deviation within ±0.1mm,the maximum dimension deviation is less than ±0.3mm,and the surface roughness of different positions is increased to the range of Ra25?m to Ra50?m;(4)Through the analysis of multi-index orthogonal experimental,under the conditions of 50°Bé,10 s single immersion time and 2 immersion times,the results show that the surface roughness can reach Ra12.5?m,and the thickness of the coating is about 0.45 mm.After controlling the curing process of the coating by robot motion,the flow state of the coating curing process can be controlled,and the uniformity of the coating is increased by more than 50%.Under the combined effect of ASHM method and surface coating process,the dimensional accuracy and surface quality of the parts have been improved,which can meet the requirements of precision casting,effectively reconcile the contradiction between processing efficiency and forming quality in additive forming process,and open up the application prospect of selective laser forming technology.