THE FOURIER SERIES USED IN ANALYSE OF THE CAM MECHANISMS FOR THE SHOEMAKING MACHINES (PART II)

A computer assisted procedure for the cinematic analysis of the mechanism of a cam is essential in making a certain type of research operations. They mainly refer to the optimization of operations running on specific machinery, or to the re-design of the mechanism, in order to make the mechanism digital. This analysis seems even more important, when we consider the fact that most of the machines used in shoe industry nowadays use a cam mechanism. The paper is devided in two parts. In first part, it is elaborated a method of finding of a function G(x), belonging to a Fourier series, which approximates the numerical values {xi, yi}, with the biggest accuracy. Finding the function that approximates the most accurately the data set, for the position parameters of the follower S(ω), () will lead to a complete kinematic and dynamic analysis of the cam mechanism. These values repeat with T = 2π period. In second part, the method is tasted using MatCAD work sessions which allow a numerical and graphical analysis of the mathematical relations involved, in order to test the reability of the method. The set of experimental data are resulted after measuring a cam mechanism of a machine used in shoemaking

THE FOOTWEAR DESIGNING SESSION USING CRISPIN DYNAMICS ENGINEER. PART II: Creating the parts, Estimating the material consumption, Grading

The diversification and customization of products are important characteristic of the modern economy and especially of the fashion industry. Because of this, the lifetime of the footwear product is very short and result the necessity to cut the design and production time. By classic methodology, designing footwear is a very complex and laborious activity. That is because classic methodology requires many graphic executions using manual means, which consume a lot of the producer’s time. With CRISPIN Dynamics, one can visualize a range of designs on-screen; work out the costs of a new style and even cut out sample shoe components. Reliance on manual skills is largely eliminated, so the staff can work creatively, but with increased accuracy and productivity. One can even send designs to a distant office or manufacturing centre in a matter of minutes. This paper presents the basic function of CRISPIN Dynamics CAD Suite Engineer for footwear design. The process of new product development has six stapes: digitized form of the medium copy, last flatting, model drawing, creation and management of individual parts, estimation of material consumption, multiplying the designed footwear product’s pattern. This product has been developed for shoemakers who wish to ensure that their business remains competitive by increasing the efficiency, speed and accuracy of pattern development and grading

STUDY REGARDING THE STITCHING STRENGTH OF MATERIALS USED FOR FOOTWEAR UPPERS MANUFACTURING

The shoes manufacturing implies the use of various types of leathers, leather substitutes and fabric. The sewing plays a very important role in shoe making, having an impact both in terms of functionality and outlook. One of the most important indicators of the sewed products quality is seam strength, which is influenced by a series of technological parameters such as: the shape of the needle’s top, the needle’s diameter, the seam thickness, the number of seams, the gauge of the thread, the type of seam and the material type. This paper studies the stitching strength of the full grain leather and full grain leather shiny surface used for footwear uppers, in order to improve productivity and seam quality.The experimental researches obtained for the stitching strength allow calculating the weakening coefficient of the material in the process of sewing (a= 0.33-0.48). The “a” coefficient is dependent on the stitch density, the shape of the needle’s top and the joined materials. In terms of stitching strength, the results indicate that the full grain leather obtains higher values than the full grain leather shiny surface