Research Machining A 3D Free Surface Of Two Novel Parallel Mechine Tool

Parallel Machine Tool (PMT), a new-style machine tool, complements the traditional NC machine tool perfectly. With the development of the PMT technology, the potential of the lower-mobility PMT will be revealed. Based on the analyses of the current situation of the lower-mobility parallel machine tools home and abroad, this dissertation focuses on the characteristics of 3-DOF parallel machine tools by using analytic approach and computer aided geometry approach, which are proposed to machine a 3D free surface and letter.By using the geometric constraint, the dimension constraint, the dimension equation and the dimension driving techniques of CAD, two novel 3-DOF parallel manipulators 3UPU and 2UPU+SPR are created.The position, velocity and acceleration of 3-DOF parallel manipulators 3UPU and 2UPU+SPR are studied by analytic approach; the position and workspace of 3UPU and 2UPU+SPR are studied by computer aided geometry approach.Based on the geometry constraint and dimension-driving technique, a 3D free surface and a guiding plane of tool path are constituted. The parallel simulation mechanism, the 3D free surface, and the guiding plane of tool path are combined together, and two novel 3UPU and 2UPU+SPR simulation parallel machine tools are created for machining 3D free surface. In the light of two specified tool paths and letter, the extension of the three driving rods and the position of the moving platform are solved and visualized dynamically. Based on the computer simulation results, some analytic formulas are derived to solve the extension of driving rods of two parallel machine tools in reverse solving process.The machining a 3D free surface and letter of two parallel machine tools are simulated by using CAD. The previous job's visibility of the parallel machine tool is achieved.The control system is developed for the asymmetric 3UPU parallel machine tool. Open architecture composed of PC and motion-controller is adopted for the system hardware. The control software, based on Windows Operating System, is designed. The basic control functions are realized, the test-bed of the asymmetric 3UPU parallel machine tool are programmed.From the simulation results and analytic results, it proves that the computer simulation machine tool approach is equivalent to the analytic approach to machine 3D free surface and letter. The computer simulation machine tool approach is straightforward and without compiling computer any program, and is also advantageous from viewpoint of accuracy and repeatability.The research work of this dissertation establishes theoretical basis for the further research of the 3-DOF parallel machine tools practically.