MECHATRONIC SYSTEM DESIGN AND CONSTRUCTION OF A CNC MACHINE FOR CUTTING STYROFOAM PARTS FOR RC PLANES

Flying radio controlled, RC, planes has become both a sport and a form of entertainment that attracts an increasing number of practitioners worldwide. RC plane hobbyists design and build reduced-scale airplanes, unmanned aircrafts or replicas of existing full-scale ones, and fly them as often as possible to develop the necessary skills to go from basic flights to complex maneuvers and acrobatics and to race against other planes. Unfortunately, many practice flights do not go as planned and end with physical damage to the aircrafts. Companies dedicated to the production and marketing of RC planes require Computerized Numerical Controlled, CNC, machines to cut different parts for these model aircrafts due to their geometrical complexity, such as the case of the wings. Airplane wings must be light, strong and at the same time they have a tridimensional shape which is difficult to obtain by means of conventional manufacturing processes such as milling. Styrofoam is a convenient material for the fabrication of RC plane wings. The most common way to cut Styrofoam parts is by means of a taut hot wire. In order to achieve the complex shape of the wing, starting with a block of Styrofoam, the motion of the two ends of the taut hot wire must be carefully controlled and synchronized, to keep the tension in the wire and to obtain the desired shape in the part being manufactured. The best way to get this precise control for the two ends of the wire is by means of computerized numerical control. The aim of this research is to illustrate the steps for the mechatronic system design and construction of a machine for cutting RC plane Styrofoam parts to be used in the manufacturing of the aircrafts and the fabrication of spare parts for repairs after crash landings. The details for the development of each step of the mechatronic system design methodology are illustrated. The steps include design requirement specification, conceptual design, CAD modeling, structural analysis, sensors and actuators specification, assembly and testing. Once the functioning of the machine is validated, the quality of the manufactured parts must be tested so that they can be fitted to the corresponding aircrafts. The results demonstrated that the application of the methodology for the design of mechatronic systems facilitates the development of a robust device, such as a CNC machine, which synergistically combine the advantages of precision mechanics, electronics, control systems and computers to manufacture high quality parts for the RC planes industry.