Study On Some Key Technologies And Realization In Shoe Last CAD/CAM System

Shoe last is an important model tool in shoemaking. Its producing level plays a key role in shoe industry. So it is the trend in the future that the advanced technologies such as CAD/CAM, computer and information processing are required to improve traditional shoe procedure, because we lag considerably behind of Western counterparts in this field. Supported by the national fund plan, a project is carried out by our group, which includes the CAD/CAM software system, shoe last 3-dimensional measurement instrument, numerical control machine and shoe leather design. The thesis mainly researches about the key techniques in CAD/CAM software system.After analyzing the technology's development status quo and comparing the modeling techniques, the author presents a discrete mathematic model for shoe last by using cubic B-sampling curve. The description of a complex shoe last surface is simplified to curve expression and then to plane curves, which results in considerable simplification of algorithms in shoe CAD/CAM. Under this discrete model, the whole system data are standardized and make it easier and possible to realize many shoe last CAD/CAM techniques.Several mathematic methods are described in chapter 3. They are: l)Iinear fractionization in any point calculation of shoe surface. 2) Adaptive Tangency (AT) method with known plane sectioning shoe last in shoe last transform. 3) curvature of plane discrimination to recognize sharp points region and sharp points interpolation in edges detection. These methods are very important and useful in algorithms realization.Shoe last design is divided into local modified design and whole shape design. As traditional deformation methods are not suitable to shoe last, this paper puts forward a novel method named Slope Adaptive Deformation (SAD), based on curve slope change. For deformation quantity, local modification is converted to change main U lines and V lines coordinates to form new U lines and V lines. According to design standardization, such modifications design as shoe last width, length, whole amplification and reduction are implemented and then the new characteristic point data are recombined and standardized by cubic B-sampling curve.. As local revision brings to edges point change, a combined method is given to overcome the existed problem.In the calculation of knife position point in shoe last CAM system, we first adjust the shoe's machined axel line to make it consistent to measuring axel line, and thenform the machining data. Aiming at the defection of Discrete Surface Dynamic Tangency (DSDT), we point out three existed problems and give corresponding solving methods, i.e. adjusting projected region by using local structure layer and micro-structure layer, estimating the position region of machining point by calculating characteristic point step by step, and obtaining final accurate machining points through point-neighborhood processing, hi shoe last machining, relative motion data is constantly adjusted to avoid interference occurrence.Finally the developed shoe last CAD/CAM system software with friendly interface and full functions is introduced. Based on all research work, the whole system has reached or exceeded the initial specifications and the system prototype is developed successfully, which establish a firm foundation for shoe last CAD/CAM technology practice.