Research And Development Of Interpolation Control On CNC System For Gear Machine

Interpolation is the core function in CNC system, the algorithm and the size of the functional module of interpolation directly affect the performance of the CNC system. The hardware platform of ARM+DSP+FPGA is adopted in the CNC system of this paper, because DSP6713is a floating-point chip, which has more efficiency and higher computing precision in processor performance, and it is of great significance to improve the performance of the system as the interpolation processor of gear CNC system.The development overview of CNC system and interpolation is introduced firstly, and then the hardware platform and the software structure of CNC system are discussed, also the implementation rationale of DSP6713in CNC system is discussed, and resource time-sharing mechanism of CNC system is realized in6713, and registers initialization is introduced in the peripheral of6713, the implementation process is detailed elaboratedly by secondary leads of the EMIF extended in6713.In the general interpolation modules of CNC system, interpolation preprocessing and interpolation real-time computation are detailedly designed. Interpolation algorithm employs the method of time division, and an interpolation procedure is called in every interpolation cycle, and each corresponding feed of the axis is calculated. Speed processing is chiosen by T type or S type, which is processed before the interpolation performance. The conventional interpolation such as G01G02/G03etc is depthly discussed on the interpolation algorithm and the interpolation process, and these have been realized in the CNC system which has been independently researched and developed. Finally given that the size of the interpolation functional module is one of the important indicators of performance of the CNC system, the quadratic curve interpolation and screw thread interpolation algorithm which are commonly used is studied.In the design of the following interpolation module of gear’s NC system, the concept of the following interpolation is carried in the detailed elaboration, including the electronic gear box interpolation of gear hobbing CNC system and the electronic screw guide interpolation of slotting CNC system. The processing technique is deeply analysed between the gear hobbing machine and the gear shaper machine, and the following coupling coefficient is detailedly infered, and finally the interpolation arith model and the real-time interpolation processing scheme are given.Finally based on the analysis of the process of machining the non-circular gears, the following interpolation controlling mathematical model of non-circular gear is put forward, and the following coupling coefficient needs real-time computation, so a high requirement for CNC system performance, and the mathematical model is proposed based on discrete interpolation. The interpolation of equal arc length and polar angle employ some small linear fitting, and the cubic spline interpolation is proposed in the analysis of the deficiencies of these two kinds of interpolation algorithm, and the speed and acceleration of each axis will not fluctuate, the quality and precision of machining non-circular gear is significantly improved.