New Approaches to Determining Shortest Cutters and Work Piece Setups without Over-travel for 5-axis CNC Machining

Five axis CNC machining centers are widely used in the industries for producing the complex parts. Due to two more axes as compared to the three axes machining, it provides the efficient and flexible way of the machining. Besides this flexibility, accidental collision possibilities between the cutting system and the other moving parts of the machine tools are also increased. These collisions could be avoided by changing the orientations of the tool during the tool path planning or by adjusting the cutter length and the tool holder size after the tool path generation in the part coordinate system. Collision detection and removal by the optimum cutter length depends on the configuration of five axis machine tools. No. of possible candidates for the collision may vary with the configuration of the machine tools. Since the fully utilization of the existing machining facilities in the industry is also in high demand, therefore, after selecting the one of the critical parameter of the cutter length, the maximum utilization of the work space of the 5-axis machine tools is another critical task. This dissertation comprises of two main works. In the first research work, a comprehensive approach for the determination of the optimum cutter length for the specific configuration of five axis machine tool is developed. The complete cutting system (the tool, the tool holder and the spindle), the work in process model and the fixture are the three possible candidates for the collision. The work in process model and the fixture are represented as the point cloud data and the tool holder and the spindle are represented as a regular shape of the truncated cone and the cylinder respectively. Collision checking is conducted in two steps. In the first step the KD-tree data structure is employed on the point cloud data and a method is developed which confines the searching of the point cloud data in the local region and in the second step a new mathematical model for the collision detection between the points in the local region and the cutting system is established. This model also has the capability of removal collision with the optimum cutter length. In the second research work, kinematics of the table rotating and spindle tilting 5-axis machine is developed and setup parameters for mounting the part on the table are defined. A precise method for the determination of the setup parameters, which gives the opportunity of fully utilization of the work space of the machine tool, is developed. Many machining simulation software such as vericut can simulate the G-codes for the given setup parameters of the part and can verify the over travel limits of the machine tool as well as accidental collision between the moving parts of the machine. In this research, the developed method for the determination of the setup parameters gives the guarantee of complete machining of the part without over travel limits of the machine translational axes. This research is based on the predetermined machining strategies, which means, tool path is already given in the part coordinate system.