Research On The Key Technology Of 6-TPS Parallel Platform CNC Milling Machine

In order to achieve the ability of five-axis milling, make full use of traditional milling machines, and gain some experience in amending traditional machines, two kinds of augment schemes are introduced. The feasibilities and correlative theories are discussed in detail. The 6-TPS parallel platform milling machine is designed and fabricated finally.Three coordinate frame(workpiece frame, upper platform frame, base frame) are assigned for the convenience of the programming and calculating, the translation relationships between them are derived. The proper Euler orientation angles are adopted, and the translation from the cutter's position and orientation in workpiece frame to the lengths of six driven struts is analyzed, while the translation from the latter to the former is also discussed. To satisfy the requirement of the velocity checkout for the cutter location data file(CLDFILE), the kinematics problems of the milling machine are analyzed in detail, and the position sensitivity and orientation sensitivity are derived to optimize the structure parameters of the milling machine.The workspace of traditional Stewart machine tool is the reachable space of the movable platform, but it is not the same in these schemes. In this paper, the reachable space of the cutter in the upper platform frame is considered as the workspace of the milling machine. In order to verify the CLDFILE rapidly, a new approach is adopted. The radius and height parameters of the inscribed cylinder at different cutter tip height are recorded in the data sheet of the workspace database, the cutter oblique angle parameters are also recorded. With the help of these datasheets, the efficiency is improved evidently. On the other hand, the dynamics problems are analyzed with a view to the influence caused by the inertia of six driven struts, mass of upper platform and mass of main axis.Because of the coupling relationships between the cutter position parameters and the structural parameters of parallel mechanism, a new verification approach is necessary. This paper presents an approach adopting classifiable verification with weight value. With the help of a hole with certain radius on the upper platform, the cutter position parameters are coarsely verified using the parameters of parallel mechanism, then the parameters of the latter are also verified using the former. The twice optimization method and amended Fletcher-Reeves algorithm are presented for improving the efficiency of verification. After several rounds verifications, the structural parameters of 6-TPS milling machine are verified to meet the requirement of machining precision. Through amending the orientation parameters of CLDFILE, the phenomenon of"washboard"is disappeared.The paper introduces some problems of traditional NC software, such shortcomings as complex structure, difficult upgrade and difficult maintenance, and presents realizing component programming with the help of COM technique. The new NC software adopted three level structure, including application level, COM components level, database level. The component aggregation technique is introduced, and The NC software data stream among the components is discussed. This software structure is be propitious to the rapid programming, rapid substitution, rapid upgrade of COM component, and meets the requirement of Open NC system.The related theory analyses on XY-RPS milling machine are derived. The paper presents RPS constrain equations, amended forward kinematics solution and compares XY-RPS milling machine with 6-TPS parallel platform milling machine with regard to cutter workspace , kinematics simulation.The 6-TPS parallel platform milling machine is designed and fabricated. Hand-control module, workpiece locating module and trouble hunting module are introduced respectively. The 50 structural parameters are verified successfully and proved the theory validity.