Optimization of strip-layout using graph-theoretic methodology for stamping operations on progressive die: a case study

The design of the progressive die stamping process is optimized through minimizing the number of die stamping stations in the strip layout to reduce the die cost. In order to accomplish such end, in this study, a graph-theoretic based method is implemented to model and optimize the strip layout design. This method starts with mapping stamping features into stamping operations. This step is followed by constructing two graphs to model the precedence and adjacency constraints among stamping operations based on a set of manufacturing rules. These two graphs are called: operation precedence graph and operation adjacency graph. In the next step, a topological sorting algorithm clusters the operations into partially ordered sets. Then, a graph coloring algorithm clusters the partially ordered operations sets into final sequence of operations. The graph-theoretic technique has been implemented on a part currently manufactured by laser cutting process technology in some Egyptian factory in Cairo. This study indicated that the graph-theoretic technique offers several advantages including the ease of programming and transparency in understanding the obtained strip layout design. This is besides being a systematic and logically approach to obtain an optimized strip layout design. In general, the progressive die manufacturing can increase productivity of sheet metal works in Egypt, only in situations of mass production. The limitation is that it requires considerable skill level and training for labor to conduct die strip layout design.

Digital Strip Layout Design of Multi-Station Progressive Die

Strip Layout design plays a key role in multi-station progressive die design, and the traditional method of designing layout is complicated, timewasting. To design layout of progressive die with PDW is efficient, easy to be modified. In this paper, the process of building layout is discussed. First of all, sheet metal should be pretreated to build immediate stage, and the suitable method can be chosen to unfold sheet metal according the configuration feature of the product. Secondly, it needs to build the assembly structure of progressive die, called initialization. Thirdly, with tools including Blank Generator, Blank Layout, Scrap Design, and Strip Layout to finish layout design. In the end, the paper takes a sheet metal for instance to finish the layout. The method of designing layout with PDW improves the traditional method’s deficiencies, and improves the efficiency greatly.

Optimizing the Organization Models of Control Lines in Chinese Waterfronts

There is no special law or regulation to guide and control the waterfront development in China. Such development can only obey the general laws and regulations from state to city. Blue Line (the control line for water protection area), Green Line (the control line for urban green space), Red Line (the control line for building, road and bridge, etc.) are three main control lines in Chinese waterfront development. There always show the parallel strip layout of these three lines in Chinese waterfronts, which results in the tedious strip layout of green space, road and building. It cant satisfy the trends of multiple waterfront developments, multiple utilizations of water resources in the waterfronts of city center. So, its necessary and urgent to optimize the organization of control lines and discuss the multiple organization models so that the flexibility of waterfront layout can be increased, the comprehensive utilization of waterfront land can be fulfilled, and the urban form of waterfront can be enhanced. Meanwhile, it is also important to formulate special laws or regulations for waterfront, to encourage the effective intervention of urban design, to strengthen the cooperation among different bureaus and specialties, which will promote the implementation of multiple organization models of control lines.

Research on Progressive Die Design for Asymmetric U-Shaped Contactor

The pressing technologies and the forming difficulties of the asymmetric U-shaped contactor were analyzed. The strip layout was designed for progressive pressing from piercing to bending. The die structure was designed in three plates mode, guiding with ball cage bush and pillar mechanism. The multiple steps bending stations and sliding inclined wedge mechanism were designed to implement the critical forming function. The volume production proved that this toolset’s structure was robust at high stamping speed and the products meet the high quality criteria. A valuable universal design rule was concluded for similar product’s toolset design.

Computer-Aided Process Planning of Strip Layout in Progressive Dies

This paper proposes a two-step process which uses the knowledge gathered in sheet-metal manufacturing practice as the basis to find proper layouts of strip in progressive dies. In the first step, manufacturing knowledge is used to formulate various rules to cluster the punches into five categories for reducing the searching space of feasible layouts. Evaluation functions are then applied to find the better ones from the feasible layouts. This two-step process provides a new approach to solving the problem of “explosive combinations” in strip layout design

An Algorithm to Optimal Two-Stage Homogenous Strip Patterns of Rectangular Pieces

This paper presents an algorithm for two-stage homogenous strip patterns for rectangular pieces. The algorithm is appropriate for the shearing and punching process. It proposes the two-stage homogenous strip patterns that can be cut into homogenous strips in two stages, with another two stages being required to cut the strips into pieces. Firstly vertical cuts divide the stock sheet into segments, and then horizontal cuts divide the segments into homogenous strips. A homogenous strip contains pieces of the same type. The algorithm uses a dynamic programming recursion to determine the strip layout on each segment, solves knapsack problems to obtain the segment layout on the sheet. The algorithm is tested through benchmark problems, and compares with two famous algorithms. The pattern value and the computation speed of this paper’s algorithm are better than that of the classic two-stage algorithm. What’s more, this paper’s algorithm can give solutions very close to optimality.