The Study Of Powder Spreading Device Of The Molding Device Of Selective Laser Sintering

In the molding process of selective laser sintering, powdering and preheating directly affected the machining accuracy and mechanical properties of the workpiece. This paper conducted in-depth study on the powdering and preheating, which are the key technology of selective laser sintering, and analyzed the factors which they have effect on the molding, and using these factors to improve the machining accuracy and mechanical properties of the workpiece. Besides, in order to do the experiment conveniently, the author designed a simple laser sintering simulation test system.Firstly, the author analyzes the problem which how powder and preheating directly affected the machining accuracy and mechanical properties of the workpiece. According to the results to redesign the powder spreading device, the forming cylinder, which comprises a ball screw, a synchronous belt, stepper motor. The down-setting ball screw structure is adopted to save space. The driving elements are totally designed, with accurate calculation and the precision of the device is checked as well. Next step, as for the powder spreading device, after comparing advantages and disadvantages of double-tank powder supply, the structure that combines mobile funnel with powder spreading cylinder is selected, in order to improve the powder spreading efficiency.Simultaneously, the device is optimized, using a line motor that generates horizontal velocity and a d.c.motor that provides rotation powder to implement parameter optimization for the two velocities above. Secondly, the author designed the preheating device. It is concluded that pre-heating device commonly used radiation heat transfer by analyzing the form of preheating in domestic and foreign related equipment.In this paper, the author engages in establishing and analyzing a mathematical model of the radiation, and then through the ANSYS numerical simulation, it gets the conclusion that heater, shape and installing height could affect the heat flux distribution of the powder bed by analyzing the simulation results. The height should not be too high or too low. Simulation obtained that in this equipment installing height of 180 mm was the best value.Laser sintering is a continuous process, the problem which the prediction of the layer quality is very difficult.In this paper, the author used the BP-ANN to establish the mathematical model between the powder spreading parameters and the layer quality.According to the sample to train a good mathematical model,and finally through the smaller error, shows that this model is reliable.The author designed a simple laser sintering simulation test system. The simulation system can simulate all themoving parts of the geometry of equipment for sintering movement simulation, to achieve three-dimensional dynamic simulation show that the laser sintering process.The system provides a digital tool for analysis of SLS process, control, visualization, also provides the corresponding reference on the mechanical parts of the actual selective laser sintering production manufacturing, which can reduce the process defects of SLS process effectively, as soon as possible made the selective laser sintering rapid prototyping manufacturing technology(SLS) meeting the direct manufacturing of parts with complex industrial demand.