Research On The Algorithm For The Guillotine Cutting Of Blanking Strips

Computer Aided Nesting(CAN) is an important branch of the computer aided design and manufacturing, which is widely used in many industries in national economy, such as machine building industry, equipment of traffic and transportation manufacturing, sport products processing industry, wood-processing industry and so on. The optimal layout technologies are used to deal with the demand of blanks on the materials, to get the optimal arrangement of the blanks and maximize the material utilization, and save materials, simplified cutting process, reduce the production costs.In real production, cutting nesting is applied in many wire rods, coil material and plank stuff, traditional layouts worked by men leads to the waste of manpower and raw material, and it is difficult to obtain the ideal layout scheme, and increased production cost. Accordingly, using CAN to research the problem of layouts and design a reasonable nesting scheme, improve the utilization, reduce the work of nesting, simplify the cutting process. As a result, reduce the production cost. Accordingly, there is an important actual purport for enterprises using advanced CAN technologies.The shearing and punching process is often applied in manufacturing to cut the metal sheet, including two stages:the strip cutting stage and the items punching stage. In the former stage, the sheet will be cut into strips by a guillotine shear, that is the strip cutting stage; then the items are punched from the strips by a stamping press. Using shearing and punching process, the related strip parameters and items size have been set in the mold design, and can not be changed later, but the material utilization can improved by nesting the strip on raw material. In the strip layouts process strips of different size allowed, and items in the same strip must be the same size, but the long and direction of strips can be different.Rectangle packing problem is a widely existed problem in optimal layouts, at present, scholars in and abroad have worked deeply on the research of rectangle packing problem, especially on the two-dimensional rectangle cutting problem, and proposed many algorithms, such as dynamic programming algorithm, linear programming algorithm, branch-and-bound algorithm, ant colony algorithm, genetic algorithm and so on. Those algorithms are aimed at improving the pattern utilization, shortening the computation time and simplifying the cutting process, but a few for cutting problem about items in punched strips.This paper discussed the items in shearing and punched strips:the same size items, that is only blanks of the same size can appear in a strip and the parameters of items and strips are know; there is no constraint on the number of item and strip; the purpose is get the minimum number of the strip cutting stage and the items punching stage when the value of the single sheet (the number of items included in sheet)is maximum, that is the simplest optimal pattern.The details of this paper are as follows:Firstly, research on the current pattern algorithm of rectangular blank, and choose an reasonable algorithm as this paper algorithm. This paper choose dynamic programming algorithm for research.Secondly, based on the algorithm which has been choose, we improve the algorithm, and design the punched items in strip-cutting system, verify the feasibility and effectiveness of the improved algorithm, and use it to solve the problem present in this paper.Finally, the improved algorithm are tested by various instances, the computational results indicate that the improved can get the minimum number of cutting,simplify the process and reduce the product cost through the comparison and analysis,when the number of items included in raw material is maximum Keywords:Rectangle packing; Punched strips cutting; Cutting stock; Dynamic programming...