According to their developable characteristic, curved surfaces can be divided into developable and undevelopable ones.
按照它们的可展性质，曲面可以分为可展曲面和不可展曲面。
2
The mathematical model of parallel and undevelopable ruled surface was constructed, the algorithm for NC ultrasonic grinding surface was founded.
建立平行、不可展直纹面数学模型，确定超声磨削加工平行、不可展直纹面时磨轮空间轨迹及其算法。
3
There are many different methods to develop the same undevelopable curved surface, the criteria must be created to evaluate which one is the most appropriate.