The Method Of Mechanical Irregular Nesting

The two-dimensional packing problem arises in everal industries:, Which is mainly applied in the industries such as die cutting, shipbuilding, garment, leather cutting, etc. The slight improvement in packing efficiency can make great economic profits for these industries. On the other hand, the packing problem belongs to a class of combinatorial of optimization problems with high complexity.The Problem of Optimal layout belongs to the NP-complete Problem with tiptop calculate complexity, the main works proposed in this dissertation are listed as follows:(1)The main research of Irregular parts contain empty, arc profile preprocessing method; introduced the two-dimensional irregular parts nesting space vector in the representation and polygon separation criterion method and the advance and retreat method. The polygon separation test can be deduced to the point-in-polygon test and the intersection test of line segments.The method of advance or retreat can be described as follows:if one part is separated from the other, then it slides one step forward; else it slides backward; it keeps doing so until the contacting error satisfies the required accuracy. An example was provided to verify the highspeed of the contacting algorithm.(2)An irregular packing algorithm based on the principle of minimum potenti al energy was proposed, which reveals the physical meaning of packing problems: the part always tends to keep its center of gravity as low as possible by means of translation and rotation, thus a more compact layout being obtained. In the in vestigation, in order to find the optimal packing attitude with the lowest center of gravity, some equally spaced points need to be located on the sheet, and around each point, the part is rotated in a certain angle interval. Computational experim ents show that HAPE is credible and is of a clear physical meaning, and that it needs no calculation of NFPs and is capable of dealing with arbitrary irregular pa rts. The irregular packing algorithm is combined with hill-climbing (HC) and sim ulated annealing (SA), thus two hybrid algorithms being proposed. By lots of test s and comparison, the performance of these two hybrid algorithms was studied es pecially how the RN and PPD (packing point distance) affect the packing density. The phenomenon of Sweet RN was found in hyrid algorithm and its behaviour was studied(3) we have developed a two-dimensional layout software based on the above research achievements.