Research On Some Key Problems For Fused Deposition Modeling

Fused Deposition Modeling(FDM) with a number of advantages of its relatively inexpensive equipment and materials, low running costs, operation-friendly, pollution-free, suitable for the office environment, encompasses a wide range of applications including 3D printing of design and concept models, assembly and functional testing for small and medium enterprises and educational institutions. Low-speed scanning and filling and bad-accuracy filament are the biggest differences of FDM to other laser-enabling rapid prototyping processes. FDM is more sensitive to the quality of the support and toolpath. This makes the optimization of support and toolpath especially important.This article is involved in research and development in HRPF fused deposition modeling equipment. The key technical problems are including the extrusion head, control systems and some software key algorithms such as support generation, toolpath planning and optimization.First of all, as the core enabling technology of the system, the extrusion head is discussed and practical solutions are proposed to address some key problems including the filament instability, the spinning of the friction wheels, the overflow of the delivering material entrance, on-off response lag (including salivation), temperature controling and the plugging of the nozzle. The reliable and stable work of the extrusion device creates the conditions for the follow-up process test.Support structure for fused deposition three-dimensional printing equipment is discussed and a novel support structure of sloping wall structure with its automatic generation algorithm is proposed based on STL file data. This new structure reducing the volume of the support helps saving a lot of materials and improving the modeling efficiency.Many types of tool paths for fused deposition three-dimensional printing device are analysed. A novel tool path - parallel raster - with its planning algorithm is proposed. This tool path makes the forming process tended to parallel approximation, a uniform temperature field in order to reduce the amount of warpage. At the same time, this path also reduces the number of the path of small-sized segments, and then improves the vibration characteristics of the equipment while in high-speed running.To improve the forming quality of parts surface, serval path optimization methods are proposed and realised for the fused deposition three-dimensional printing. They are path sequencing optimization algorithm based on potential starting point and adding node method, combined optimization algorithm based on two different merger principles, and end node ensconcing optimization algorithm for the path hybridized by raster and courtour offset paths.A control system based on model of personal general PC + PLC is designed and carried out for Fused deposition three-dimensional printing device, in which massive data rapid prototyping is required to be processed by dynamic transmission through PLC Freeport communications, and a real-time three-axis motion control must be achieved too.For the on-off response lagging phnomenon, a new control strategy -detouring on-off control strategy is forwarded, which transforms the non-controllable filling bug in "point" to in a "line" segment on average. Cooperated with end node ensconcing optimization algorithm and high-speed jumping, it helps reducing the filling defects of parts.In conclusion, the problems such as on-off response lagging, distortion, support and toolpath generation and unreliability of extrution head, have been solved in the fused deposition modeling processing, which has laid a certain amount of theoretical and practical basis for its further development.