Study On The Method Of Profile Failure-based Laser Rapid Prototyping For Coated Sand

Profile Failure-based rapid prototyping (PFRP) is a brand new research direction in RP field. The prototypal mechanism of PFRP is also based on discrete-accumulated principle, but is different from general rapid-prototyping approach which called part-building manufacture, exactly speaking, PFRP is part-dividing manufacture. That is, by forming a failure-profile on every layer, a parting surface will build up in the working chamber, then the material's strength will enhance after being heated and the object part will be obtained by stripping the waste materials. Distinguished from LOM, PFRP can process the powdery materials. Employed foundry coated sand as raw materials and realized the profile failure by laser ablation; this article presents an experimental study on the methods and applications of PFRP. Based on the summary of slicing technology at home and abroad, a method of direct slicing using SolidWorks software is presented in allusion to several existing defects of slicing technology based on STL file. This method can effectively acquires the section's contour information from solid models and converts it to a piecewise rational cubic polynomial form, which can be easily turned to the tool path, the filling path, and the grid mould-parting lines of the non-part. With the machine code created by this method, the 3-D profile reconstruction and the solid reconstruction are successfully realized using SolidWorks. A new control system for RP is developed based on the test machine named Quick Casting CAD/CAM. In allusion to the 2- casing configuration of the machine, a control method for rapid feeding is also presented. However, the control system can process multi-part with respective scanning speed or single part by segment scanning, which improves the efficiency and makes full use of the raw materials.An experimental study on the process of PFRP is presented. Influence of laser power, scanning speed and layer thickness on manufacturing accuracy and detachability of workpiece is discussed. Relations between p/v (P represents the laser power, v represents the scanningspeed) and laser-ablated depth are investigated. And it is found out that formula p/v = constantexists under the precondition that the laser-ablated depth is higher than the layer thickness.Quick casting on metal part based on PFRP was achieved and a process chart for quick casting was presented. Finally, a bevel gear, an impeller and a gear group were produced successfully by this method.