Research And Implementation On Algorithm Of Tool Length Compensation In Five Coordinate NC Machining

Five-axis Numerical Control technology is the most difficult one among the Numerical Control technologies, and also the most widely used one. It involves Computer Control, servo drive and precious machine technology, and is indispensable to efficiently, preciously and automatically make propeller, turbine blade, spiral bevel etc. which have high quality requirement. As stands for the development level of a state's equipment building industry, this technology attracts more and more attention in the last few years.Tool length compensation is one of the most important functions of Numerical Control System. It can be used to simplify Numerical Control programming and make the program have nothing to do with tool length. For 2-axis and 3-axis Numerical Control System, this function has been well served. While for 5-axis Numerical Control System, the rotary axes have great influence on the motion axes. Nonlinear error is generated during the machining process, so it's necessary to research tool length compensation for 5-axis Numerical Control System.In this thesis, firstly the nonlinear error generated during the machining process is analyzed, and the result is verified by simulation experiment. And then the algorithm which implements the function of tool length compensation in the interpreter is designed. The algorithm is based on machine coordinate system. At the meantime, the experiment result is also given.In the following sections, the shortcomings of the algorithm which based on machine coordinate system are elaborated. A new algorithm based on workpiece coordinate system using tool orientation vector is proposed. After that, three ways to describe tool position are discussed. Meanwhile, the comparison and analysis in performance between the two algorithms are made. Lastly, the mathematical models of coordinate conversion between workpiece coordinate system and machine coordinate system are represented.