Research On Technology Of Twin-cutter NC Turning Programming

There are two cutters in twin-cutter turning process, which is able to shorten man-hour and improve production efficiency, and it is widely used in mass production. But it is difficult to design its NC (Numerical Control) program. In this paper, computer aided technology is adopted to develop an automatically programming system, which can accomplish the modeling of parts, process planning of twin-cutter turning, calculation of cutter location data (CLDATA), generation of NC code and simulation of the machining, and so on. The main contents are as following:1. An overview on current situation of NC technology are disscussed. CNC (Computer Numerical Control) is classified as five types according to the structure. Their features of structure and function are discussed. The development trend of NC technology and NC?programming technology are summarized by the discussion of performance, function, architecture, etc. Key technology of twin-cutter turning process NC programming is analyzed.2. NC programming procedure and method are presented. Procedure, features and application field of typical programming method, such as manual programming, on-line programming and automatically programming are expounded.3. Progressive modeling method of NC machining model is researched. According to the information content, the NC machining model is classified as production model, technics processing model, and tool model. On the basis of integrated production model, the extension data, which includes technics processing model and tool model, can be appended by the joint of extension data segment.4. Process planning method of twin-cutter turning at the same time is researched. First, we studied the planning aim, task, requirement and the assigning principle of two turrets. Then the planning method of cut-in segment, cutting segment and cut-out segment, and their cutting parameters are disscussed, in which the aim, principle and method of mechanical allowance on-line measure oriented to inhomogeneous work piece are researched especially. Furthermore, the storage structure of single machining step and multi-machining-step, and the integrated storage method of all process data are discussed.5. Generation arithmetics of CLDATA and NC code are researched. The CLDATA of twin-cutter machining is abstracted from the ISO CLDATA. The generation arithmetic of NC programming without tool radius compensation is studied, in which three abnormal conditions, including discontinuous cutter center track, point of intersection that is too far, and excessive cutting error, are settled by C tool compensation. The edition of CLDATA and NC post arediscussed.6. Simulation technology of twin-cutter NC turning is researched. First the math theory of machining simulation is studied, and the set structure of NC machining simulation system whose components, including time, input, output and so on, are defined. Hereby we set up the hierarchy structure, the logical structure, the static model and the dynamic model of simulation system. The construction method of sweep entity of cutter and rotation parts is researched, and their differential geometry invariants are calculated. NC code is unscrambled, and the recursion division arithmetic of time segment is put forward, which is the driven data of the movement or rotation parts. The CLDATA should be interference-free. To examine if there is interference between cutter flank and the work piece, an arithmetic that discussed the existence of intersecting curve between them is put forward. To examine if there is interference between two turrets, an arithmetic that discussed the existence of intersection set between two polygons is put forward. At last, the significance, content, and current level of physics simulation of NC machining are discussed.