Study On Additive Manufacturing Technology Of Complicated Curve Surface Based On 6-DOF Parallel Mechanism

With the development of industry,many fields such as the automotive industry,ergonomics,and aviation have put forward higher requirements for complex curved surface manufacturing technology,not only ensuring manufacturing efficiency and low cost,good surface quality is also required.At present,the research on six-degreeof-freedom additive manufacturing technology is in its infancy,and there are few researches on the printing parameters suitable for multi-degree-of-freedom additive manufacturing.Therefore,the effect of workspace and related printing parameters on the quality of complex surfaces is analyzed.In order to print large-sized parts,a 6-PST parallel mechanism is adopted,and the degree of freedom of this parallel mechanism is analyzed and verified based on the spiral theory.The inverse kinematics algorithm is established by closed vector loop method.Based on the inverse kinematics algorithm and combined with the constraints of parallel mechanism,the fixed attitude workspace and the fixed position workspace are analyzed by boundary search method,and a typical curve surface is passed to explain the impact of workspace on print path.In order to realize six-degree-of-freedom 3D printing technology,a parallel sixdegree-of-freedom 3D printing system is designed.The main components are: parallel mechanism,cooling system,extrusion system,turntable,driving system,home return system,microcomputer,temperature control system,track controller and computer.Then,the hardware composition of each component is designed in order to print complex curved surface.In particular,the strip nozzle has been designed and optimized to improve printing efficiency by at least 6 times compared to conventional cone nozzles.The strip nozzle also reduce the number of bonding surfaces between the resin filaments and therefore improving surface smoothness.The application of the various functions of the control software in 3D printing is also described.The printing parameters are calibrated,and then the effects of printing parameters are separately analyzed from the heating temperature,the extrusion speed,the nozzle movement speed,and the cooling system.It is found through experiments that the surface roughness of the molded resin is best at 210 °C,and the average height difference of the surface microstructure is only 316?m.Because the coupling degree between the extrusion speed and the nozzle movement speed is relatively high,the ratio of the two items is set as a coefficient K,and the forming effect is better when the coefficient K(28)1.6 obtained through experimental analysis.In order to achieve unsupported printing,the cooling system is designed and optimized,and the effectiveness of the cooling system is verified by experiments.Finally,the effects of the printing parameters above on the complex surface forming and the advantages of the six-degree-of-freedom parallel 3D printing system compared with conventional three-degree-of-freedom printers are analyzed by complex curve path and a typical sample.In summary,based on the six-degree-of-freedom parallel mechanism,the requirements of high efficiency,low cost and good surface quality is achieved.