The process of upper sewing is one of the most important steps in the whole shoemaking process, which affects the shoemaking scheme and the appearance of shoes directly. Aiming at improving the automatic level of the uppers sewing process, this paper presents a system which can convert the input of the image of uppers to the output of numerical control code for automatic upper sewing process. The system uses a CCD camera to get the image of uppers, and adopts existing image processing technology to carry out noise-removal processing, binarization processing, edge detection, edge thinning, and then the contour of the upper which contains the essential sewing geometric information is extracted from the image. Through vectorization, the contour is approximated to some line and arc segments that can be interpolated on general NC machines, and it is saved in the form of DXF file, finally, after postpositive processing such as path planning and offset calculation, NC code of the graphics is generated. A practical application of the system is given at the end of the paper.
As we all know, upper design are affected greatly by fashionable trends, so there exist a great variety of styles, which results in the complexity of structure and trivial details in the sewing process. At present, the majority of shoemaking factories depend on traditional manual operation, not only many skilled sewer are needed, but the efficiency is also low. In order to enhance the automatic level in upper sewing process, research institutions at home and abroad have proposed some solving scheme. SKS A20801, a kind of NC sewing machine, is equipped with an automatic programming software based on graphics which is input through a LCD touch-screen . Separated automatic programming device is also introduced in, which can convert CAD drawings to NC code .Mitsubishi Electric Corporation has developed PLK series industrial machines which can simulate the sewing path by moving the sewing needle along the upper’s folded seam before practical work .The introduction of NC sewing machine enhances the efficiency of shoe making, but these quipments are exclusive products of the developer’s, so secondary development is a hard process because of the packaging. In this paper we proposed a novel technology applied to the automatic NC programming in upper sewingprocess, i.e., the initial information is provided in the form of images, its geometric details are constructed through computer vision, which is rarely mentioned in the NC sewing machine. Compared with traditional sewing methods, the system proposed in this paper has its unique advantages, for example, in traditional sewing processing, people have to control the machine in manual operation mode to let the sewing needle trace along the sample upper’s folded seam in order to simulate the consequent sewing path , in which the unavoidable errors result in poor appearance of the shoes. In fact, due to the various upper styles, the flexibility is very limited as well. The system proposed in this paper obtains the exact moving track of the needle by calculating parallel paths of the contour which is directly extracted from the supper image, so the defect mentioned above can be avoided. The flexibility of the sewing machine is improved and an accurate parallel sewing path offset can be obtained. The automatic sewing technology based on the image of uppers integrates the image processing technology with numerical control technology, which can reduce the requirement for experienced operators and improve the efficiency. In a word, the system can meet the requirement of perfect appearance of the products and timeliness in manufacturing.
Offset of the Path In the sewing process of the upper, the moving path of the needle is not the contour extracted from the image of upper, but the parallel path offsetting a certain distance from the contour. A direct offset method is used to accomplish this process . C. Generation of NC Code The ultimate purpose of the system is to obtain NC code of the practical sewing path. This process mainly concerns the transformation from the machining information such as the contour data and processing parameter to NC code. After that, the simulation in NC machining process according to NC code is carried out to check the correctness and rationality of sewing pathThe NC code of the image of uppers can be generated through the system proposed in this paper. The system adopts digital technology to enhance the automatic level of the upper sewing machine. Through the integrated application of image processing technology and NC technology, the automatic sewing process is realized; the efficiency of shoemaking is much improved, and the appearance of the shoes can be improved. In a word, the system improves the automatic level of the whole shoemaking process and the quality of the products. It can also be used in other fields such as quilting. https://www.vssewingmachine.in/