Development of a Novel Robotically Effected Plastic Foam Sculpting System for Rapid Prototyping and Manufacturing

摘要

This thesis presents the development of a novel robotically effected plastic foam sculpting system for rapid prototyping and manufacturing purposes. The developed system is capable of rapidly sculpting physical objects out of expanded and extruded polystyrene using an electrically heated Nichrome sculpting tool. An overview of current conventional rapid prototyping systems indicated that the main disadvantages lie in the limited size of objects which can be built, the relatively long time involved to produce one part and the high cost of the systems and materials. An extensive literature and technology review was conducted on work which was similar to the novel system presented in this thesis. The literature provided many good ideas which could be applied. Two sections of experimental work were conducted. The first was aimed at simply proving the concept of robotically effected sculpting of plastic foams. A crude procedure was developed which proved to be rather tedious and manual, especially in terms of generating the tool paths. Qualitative observations of the cut surfaces were used to change the testing parameters to explore their effects and discover which parameters produced accurate and smooth sculpted surfaces. 12 tests were documented and proved that the sculpting of satisfactory surfaces was achievable. The second section of experimental work involved developing the aforementioned crude procedure to make it more automated, especially in terms of the tool path generation and optimisation step. An innovative five step procedure was developed which if followed can produce accurately sculpted artefacts using CAD models of the artefacts as the primary input. Two artefacts were successfully sculpted using the developed procedure. The first was a simple lofted surface; the CAD model of which was created in SolidWorks. The second artefact was a patient customised medical radiation therapy head and neck support; the CAD model of which was created by scanning the back of the author's head and neck with a 3D scanner. The sculpted support fitted the author perfectly. The implementation of the procedure in the two tests highlighted several points including the speed in which the whole process can be carried out. The time taken from the scanning of the authors head and neck with the 3D scanner through to the physical sculpted artefact, was a mere 80 minutes; of which only 13 minutes was consumed in the actual setup and sculpting step! This is extremely quick when compared to conventional rapid prototyping systems and CNC milling. Several areas of future work were outlined and included, tool and fixture design, automation and integration of the system procedure, tool pathing strategy for foam cutting and robot control system issues. The work presented in this thesis provides an excellent foundation for future development of the robotic foam sculpting system.