| Five-axis NC machining has a pivotal role for its high flexibility, high compound, and excellent cutting tool position profile in the complex, high-precision machining fields. However, linear interpolation is generally adopted by the five-axis CNC control systems, the actual movement trajectory between two adjacent cutter locations is a space curve, rather than the ideal programming line, as a result it creates the nonlinear error.Nonlinear error is a unique error in five-axis NC machining, and it belongs to programming errors. This paper focuses on the nonlinear error problem, and the main contents and conclusions are as follows:1. By analyzing the realization of linear interpolation of the control system, the principles of the non-linear error generation is learned; and research the kinematics algorithm of three typical structure of five-axis CNC machine tool; above on, the simplified mathematical model of nonlinear error is established based on the cutter location files.2. Under the conditions that researching the various effect factors of nonlinear error, indicates that it is useful to control the nonlinear error both in pre-processing and post processing aspects. In the pre-processing, the main purpose is to generate high-quality cutter location files by means of optimization of tool path and control the tool axis properly; in the post-processing, the focus was on the cutter location files to detect too large nonlinear error existence by using the simplified mathematical model of the nonlinear error established already and to do linear interpolation.3. Two ways to create a five-axis machine tool post processing programs: one way is to use UG / Post Builder to create a post processing program; the other way is based on the algorithm of five-axis machine tool kinematics, and applied the strategy of how to control the nonlinear error into it, written the specific machine tool post processing programs with C language. 4. NC machining process simulation is achieved based on UG / ISV model.The research of the paper has an important and practical significance in some extent at resolving the non-linear errors in the five-axis NC machining and the development of the post processing of five-axis machine tool. |
