The Method And Process For Hybrid Additive-Subtractive Manufacturing Of Coated Sand

Additive Manufacturing(AM)technology plays a huge role in building parts with geometric and material complexity,but almost all AM technologies are not ideal for accuracy and surface quality.The traditional Computerized Numerical Control(CNC)technology has the characteristics of high precision and surface quality,which can effectively compensate for the problems.Therefore,the Hybrid Additive-Subtractive Manufacturing(HASM)technology combined with AM and CNC has broad application prospects.The Selective Laser Sintering(SLS)technology using coated sand as a forming material can convert the model into a casting type(core)in a short time.However,as an AM technology,the molding quality is affected by factors such as particle size,layering technology,and secondary sintering.Therefore,the main research contents of this paper are as follows:(1)The mechanical structure design of HASM equipment was carried out,including industrial robot and tool changer,additive and subtractive as well as feeding modules.The control system and software were independently developed by the commercial controller.And the attitude adjustment,coordinate transformation and machining calibration were completed.(2)According to the laser scanning single line experiment,it is determined that the forming quality is better when the spot diameter is 0.6 mm.With the increase of laser energy density,the main resin reaction is carbonization after curing,and the initial strength is first increased and then decreased,0.33MPa at 0.090J/mm~2 and 0.75MPa at 0.157J/mm~2.(3)When the laser energy density is increased from 0.090 to 0.157 J/mm~2,the scan line width is reduced from 0.73 to 0.47 mm.The HASM method can control the thickness of the surface heat affected zone to±0.1mm,the surface roughness is controlled between Rz125~160?m,and the surface strength and microstructure can be obviously improved.Therefore,the suitable HASM process can effectively solve the problems of precision and surface quality deterioration caused by the increase of laser energy density,improve the forming strength and break the contradiction between strength and precision.