Reverse Modeling And Modifying Of Shoe-last Based On Freeform Curve Shape Control

Shoe-last is basis of shoemaking. It is not only the basis for a variety of shoes but also the body in the process of shoemaking. Therefore, shoe-last in the footwear industry occupies an important position. As the shoe-last is irregular closure curved surface composed of freeform curves and surfaces, but can not be formed by elementary analytic surface. With the development of computer-aided geometric design (CAGD), the technology of freeform curves and surfaces are widely used for modeling complex surface design, which can be modeled and modified the shoe-last by freeform curves and surfaces.There are forward modeling and reverse modeling to make shoe-last, and this article was introduced by reverse modeling method based on the point cloud data of shoe-last and GB feature data (directly related to the foot)of the shoe-last, creating the overall framework of shoe-last curve and completing the work of modeling through lofting method. Creating the overall framework is based for the scalable and local modification of shoe-last.Scalability of the shoe-last is an important content of research shoe-last to meet the needs of different sizes feet. Scalability is based on standard sample to achieve shoes and model rank difference. In this paper, scalability of the shoe-last was realized by the length and circumference of the two directions using the framework of freeform curve. In accordance with shoes on the curves rank difference, this paper was interpolated the distance between the curves back to the original pitch for length direction. In the interpolation process, the author retains the shoe-last curve of characteristics part, to guarantee the characteristics of data information in scalable process to meet the national standard. Scalability system of the shoe-last was built on Unigraphics NX3.0platform by utilizing Unigraphics redevelopment tools:UG/Open API, MenuScript, UIStyler, and Visual C++6.0, and the data information of features portion were queried quickly and easily under the different parameters.Shoe-last modifying research is another important content. In this paper, the main work is the amendments of thickness and shape of shoe-last toe. To change thickness of shoe-last head, the author makes sure the modified region and make use of the adaptive algorithm based on the slope to calculate the modified regional displacement of the point, then use the datas displacement algorithm to change the curve of the control points and make the curve through the new point in order to achieve the shoe-last thick modified. For the amendment of shoe-last toe, this paper was changed the round toe to square toe with the same measure of modifying shoe-last’s thickness.