HPRODIE: Using feature modelling and feature mapping to speed up progressive die design

For various reasons, the advances in progressive die design remain too slow compared with the increasing importance of progressive dies in modern industry. Aimed at speeding up the design process, HPRODIE, an integrated CAD/CAM system for progressive dies, was developed. In HPRODIE, three featuresthe product feature for the representation of sheet metal parts, the stamping process feature for the strip layout, and the die design feature for building the die assembly modelare introduced respectively to represent three life-cycle aspects of sheet metal parts. Feature mapping methods are employed to transfer the design information between different design stages at high-level semantics. With feature modelling and feature mapping, most of design processes can be carried out automatically. The testing results have shown that the design cycle has been cut down significantly by using this system.     

仪表指针裁搭边冲模设计

通过对仪表指针的工艺特点进行分析,为了保证工件的成形质量,提出了裁搭边的冲压方案,介绍了裁搭边排样图的特点,并设计了该零件排样图.论述了仪表指针裁搭边冲模的结构设计要点和工作过程,最后介绍了模具的装配过程,实现了该零件冲裁加工的顺利进行.     

Bestimmung funktioneller Oberflächenparameter beim Mehrfach-Streifenziehen von Stahl- und Aluminiumblechen in Zylinder/Blech/Zylinder Kontakt Geometrie

Determination of functional surface roughness parameters – Application to multipass strip drawing on mild steel and aluminium sheets in a cylinder/sheet/cylinder contact geometry Multipass strip drawing in cylinder/cylinder die geometry is especially suitable to simulate frictional contact between a smooth die and a rough sheet as occurring in stamping operations. Special attention is focused on the evolution of the plateaux topography, where essentially all normal contact and frictional shear stresses are accomodated. By using a 3-D profilometric scanning stylus relocation technique, we develop statistical parameters which represent the mean length and mean width of the load carrying plateaux. Plateaux flattening and contribution of wear debris to frictional contact is clearly more important for aluminium than for steel.     

Two-dimensional profile-packing approach for multi-torch flame cutting

Multi-torch flame-cutting machines have been widely used for cutting two-dimensional profiles in various shapes off a metal plate in a batch. The profiles of the same batch must be in the same shape and orientation, and equally separated by the spacing of the torches so that simultaneous cutting is possible. The purpose of profile packing is to obtain an arrangement of all profiles by which the necessary length of the metal plate is minimized. Traditionally, the packing process of such machines is accomplished by human discretion or some packing heuristics on one of the equally divided regions of the plate, and the packing result on this region is then duplicated to the others. Such a process, however, has limited the flexibility in placing profiles because a more compact arrangement could be achieved if cross-region placements are possible. To resolve the problem, an approach is proposed that reserves a buffer area for each region in an attempt to arrange the profiles in a more compact fashion. The proposed approach incorporates a strip representation for geometric modelling, and a bound-setting rule for accelerating the packing process. Three real cases from the metal-cutting industry are utilized to test the proposed approach, and the results show a better performance than the traditional approach. The proposed approach can also be applied to other multi-tool cutting methods wherever profile packing is required, such as plasma, laser and water-jet.     

T2铜板冲裁间隙对冲裁力及断面质量的影响

为提高冲裁件的断面质量和冲裁效率,实现对冲裁间隙的合理优化,现提出了一种新的板料冲裁试验构想:采用广泛应用于变压器等领域板厚为6 mm且相同规格的T2紫铜作为试验材料,通过更换凸模来改变冲裁间隙,完成在不同冲裁间隙条件下对板料的冲裁试验,采集并分析冲裁力随冲裁行程的变化曲线;同时测量光亮带的宽度和最大冲裁力位置,并拟合冲裁力、光亮带宽度等与冲裁间隙之间的曲线.试验表明:冲裁力在塑性变形阶段增大幅度先快后慢,而在此阶段的初期冲裁间隙对冲裁力几乎无影响,但随着冲裁的深入,冲裁间隙越大,冲裁力则越小,当进入断裂带后冲裁力急速下降;对比在相同冲裁间隙条件下冲裁力随冲裁行程的变化曲线和断面质量,可获得冲裁件断面光亮带会随着冲裁力达到最大值时而结束.研究表明,当冲裁间隙为16.67%左右时,光亮带宽度较大且冲裁力较小.     

Large-scale optimization methods applied to the cutting stock problem of irregular shapes

This paper describes a real feasibility study of applying large-scale optimization methods to the cutting stock problem of irregular shapes. We identify two approaches for minimizing waste in the cutting stock problem of irregular shapes: better packing and better scheduling of cuts. This paper is concerned with the scheduling problem only. By scheduling of cuts we mean deciding which combination of parts to group together on the cutting table so that overall material needed by all cuts is minimized. Such a problem usually requires considering many combinations. However, with the development of various feasibility requirements imposed on the column generation process this number can be reduced considerably. Furthermore, the introduction of interior-point algorithms for linear programming by Karmarkar in 1984, allows the consideration of much larger linear programming problems than was possible just a few years ago.     

Essentialsof Production and Operations Management. By EHUD MENIPAZ. (Prentice-Hall,Inc., 1984.) [Pp.706.] Price £2845.

This research is focused on the investigation of robust surface interrogation tools which can support the planning and programming of 5-axis die/mold surface machining. Surface curvature information is evaluated to determine optimal tool orientation for 5-axis machining. A method for calculating machining strip width is proposed for 5-axis cutter path generation. This paper is focused on the development of computational geometry techniques and their application to design, analysis, and manufacturing automation. The proposed planning and programming methodology consists of three phases: (1) surface interrogation; (2) machining strip width evaluation; and (3) optimum tool orientation for 5-axis machining. This proposed research can be used to improve the quality of 5-axis die/mold machining.     

Polygon plate-cutting with a given order

This note is a complement to the paper by Hoeft and Palekar [1] which describes the problem of cutting polygonal shapes from large plates of metal or glass. More specifically, we focus on polynomial time solvability for a number of subproblems of the more general plate-cutting problem. A primary result of this note is the polynomial time solvability for the plalecutting problem with a given order and convex polygons.     

Crack propagation in a strip of material under plane extension

The problem of a uniformly propagating finite crack in a strip of elastic material is solved using the dynamic equations of elasticity in two-dimensions. Two specific conditions of loading on the strip with finite width are discussed. In the first case, the rigidly clamped edges are pulled apart in the opposite directions. The second case considers equal and opposite tractions applied to the crack surface. By varying the strip width to the crack length ratio, the amplitude of the dynamic stresses ahead of the running crack is determined as a function of the crack velocity. The local dynamic stresses are found to be lower than the corresponding static values for the displacement loading condition and higher for the stress loading condition. This effect becomes increasingly more important as the crack length to strip width ratio is enlarged. Numerical results for the dynamic crack opening displacement are also presented.     

Design of Compound Die for Production of Cutting Blades for Nonactive Rotary Paddy Weeder

Press working is a chip-less manufacturing process on sheet metal through the application of immense force with the help of press tools for short interval and hence results in shearing or deformation of the work material. It is a chip-less manufacturing process by which various components are made from sheet metal. A compound die is one that is used for cutting operations only, and the operation is completed by a single-press stroke. In this article, a die was designed to serve the purpose of cutting down the blades for paddy weeder and clearances to be provided in the die were calculated so as to reduce the material consumption with reduction in production cycle time. The die thus designed served for the purpose with 73% reduction in production time, with enhanced quality and helped in enabling mass production by eliminating several processes such as marking, cutting done with the help of a cutter, shaping, and so on.     

Knowledge-based sequence planning of shearing operations in progressive dies

This paper aims to study the methodology of building the knowledge of planning adequate punches in order to complete the task of strip layout for shearing processes, using progressive dies. The usage of superimposition of punches for planning strip layout is widely accepted among progressive die designers; however the huge number of combinations of punches may turn this easy-to-understand process into a nightmare. The proposed methodology uses die design rules and characteristics of different types of punches to classify them into five groups: prior use (the punches must be used first), posterior use (must be used last), compatible use (may be used together), sequential use (certain punches must precede some others), and simultaneous use (must be used together). With these five groups of punches, the searching space of feasible designs will be greatly reduced, and superimposition becomes a more effective method of punch layout. The superimposition scheme may generate many feasible solutions. Although none of them really violates die design rules, some of them are just better than others. An evaluation function based on number of stages, moment balancing and strip stability is developed. For meeting different designers’ preferences, these three factors are coupled with various weightings, so, designers can fine tune and find better results. The whole process is not only to provide a new approach to solving the superimposition puzzles, but also to try to integrate the die design rules and designer's personal experience, which should be extremely helpful in speedier progressive die design.     

不规则零件优化排样的神经网络混合优化算法

 提出一种利用人工神经网络求解不规则件排样问题的混合优化方法.该方法首先把排样和制造工艺联系起来,将多边形各边向外扩充,为零件预留加工余量;然后采用自组织特征映射模型（SOM）和Hopfield人工神经网络相结合的方法,运用SOM神经网络对初始在板材内随机排布的不规则零件进行平移,逐步减小不规则零件之间的重叠面积,求得各零件的最优位置,再运用Hopfield神经网络对平移后的零件旋转,进行迭代运算,当能量函数达到稳定状态时,得到各排样零件的最优旋转角度组合,实现自动排样.算法可以解决不规则件和矩形件在规则板材以及不规则板材上的排样问题,实例证明了该算法的有效性和实用性.     

基于多维度物理参数影响的超高强钢热成形冷却流场仿真分析

目的 研究关键参数对超高强钢热成形模内淬火效果的影响规律,合理选择模具材料和冷却流场空间结构,达到冷却淬火后材料中条状马氏体含量最大的目的.方法 利用流体仿真软件Star–ccm+对超高强钢热成形模具冷却流场进行有限元模拟分析,采用7种不同热导率的热成形模具材料和直径为15、20、25、30、35 mm的冷却管道管径,...     

Isothermal Gas Forming of Mg Alloy AZ31 Sheet

There have been reports on sheet forming of Mg alloy in industry via the punch and die method;this paper is probably the first formal one for studying the sheet formability of AZ31 employing pressurized gas to press the sheet into a female die cavity at various elevated temperatures.The results indicate it is feasible to form a rectangular box via pressurized gas from extruded sheets of 0.5 and 1.7 mm thick.The formed box has 1:2 depth over width ratio,which should be large enough when dealing with realistic industrial sheet forming parts.Presently,forming a sheet of 0.5 mm thick is considered a technical challenge by industry,and it is conquered as demonstrated in this paper.Gas forming technique applied to Mg alloy is unprecedented and shows potential for industrial utilization.     

B1500HS材料热成形后冷冲切试验

目的研究热冲压零件冷冲切刀块易磨损寿命低的问题。方法设计开发一套多功能冷冲切试验模具,对热成形后B1500HS材料进行连续冲切试验,并对3组模具间隙、4种典型模具钢材质对应的冲切试样进行断面质量检测及统计,以此分析热冲压高强钢冷冲切合理模具间隙和典型冷冲切模具钢的冷冲切特性。结果 8%~10%料厚模具间隙在冲切初期毛刺较小,且在连续冲切过程中毛刺高度比较稳定,为合理的模具间隙范围;4种典型模具钢中,ASP60冲头耐磨性性能最优,SKD11冲头耐磨损性最差,SKH-9和CALDIE介于两则之间。结论热冲压钢的冷冲切稳定性及刀块寿命相对常规高强钢还存在较大差距,针对其冲切特性有必要开发更高寿命、高性价比的模具钢及热处理方法,以提高刀块寿命和生产效率,降低零件制造成本。     

A multidisciplinary model for floorplan design

The aim of this work is to develop and implement a model for facility layout design. The first step will be to study the traditional process of positioning, locating, or distributing the different facilities, which will be done with the help of slicing trees. Afterwards, the connections between the facilities will be handled, looking for the shortest path that communicates them all, by means of an expert system. Finally, the orientation of the original surface will be treated, using rules from feng shui. These three aspects and their different techniques will be integrated into a single application, with the addition of knowledge and experience from architects and engineers. The space-distribution algorithm of the application itself provides excellent results. Apart from that, the application considers the routing problem, especially important in architecture (but not so important in industrial plan design, when there are no walls between facilities). The application also considers the orientation of the surface, which helps to improve the comfortableness of the building and power saving. The main advantage of the application is that, while being a good tool for solving the facility layout problem, it also considers the routing and orientation of the building.     

炭布力学性能的试验研究

由于炭布种类繁多,其力学性能差别也较大,在炭布用于实际工程之前,应有一套合理的测试方法,用以测定炭布的拉伸强度及弹性模量等有关的力学性能指标,参照日本的有关试验方法,对国内外的多种炭布和粘接剂进行了系列试验研究,试验发现,炭布在破坏之前能保持较好的线弹性变化,可以认为其应力-应变为线性关系;试件的尺寸对拉伸强度影响很大,即存在尺寸效应;粘接剂的使用有利于炭纤维材料强度的充分发挥,粘接剂的种类对试件的拉伸强度有一定影响。     

Assembly system facility design

This paper addresses the design of an assembly system facility consisting of multiple assembly lines of different shapes. In such a design problem there are two conflicting objectives: (i) to minimize the overall area of the facility; and (ii) to maximize the efficiency of the material handling transportation system. We first address the optimization problem of objective (ii) when replacing objective (i) with a constraint on the facility area. We propose a mixed-integer linear program to determine the layout of a facility with given dimensions and with given assembly line areas and shapes (that cannot be changed due to technological considerations). In the layout model, the physical placement of each line within the facility is a decision variable. The objective function of the layout model is to minimize the distances traveled by material flow. Our performance analysis provides an indication of the maximal problem size that can be solved in a reasonable amount of time and we examine the effect of the problem parameters on the solution run time. This layout model is then incorporated into an efficiency frontier approach for facility design to address both objectives. Examples are presented to illustrate the use of the proposed facility design model.     

Failure analysis of an EDM machined mold-printing die used for the production of truck spare parts

A company produces truck wheel covers as spare parts for the local market. The production of these parts is based on a progressive die performing consecutive forming and selective cutting stages throughout the initial circular steel sheet. The failure occurred to the final stage of manufacturing, as the die marks, by mold-printing, the assembly configuration of the wheel cover onto the wheel rim. The paper presents a thorough failure analysis of the broken tool. The investigation includes preliminary examination, hardness measurements and chemical analysis. In depth microscopic examination was carried out using stereoscope and optical and electron microscopy. The failure mechanism was investigated from macroscopic and microscopic perspective and conclusions regarding the crack initiation and propagation were conducted and analyzed. The causes that led to the total fracture were discussed. The design of the tool and improper surface roughness are considered to be the main causes of the failure. Some complementary recommendations were proposed so to enhance the production rate of the specific tool.     

Model Building of Backup Roller Diameter Effect Rate in 4-High Mill

Software for calculating the strip profile in 4-high hot rolling mill was developed using influence coefficient method. Regularity of backup roller diameter effect rate was studied systematically using the software. The results show that backup roller diameter effect rates decrease versus the increase of strip width, increase significantly versus the increase of backup roller diameter and obscurely increase versus the increase of reduction. The difference between backup roller diameter effect rate and it is reference value increases versus strip width increasing. When backup rollers diameter is set to be 1.64 m and strip width is 1.85 m, the error of strip profile calculated using the model of backup roller diameter effect rate reference value will be 3.55μm. Based on the results, reference values of roller diameter effect rate and six power polynomial fitting coefficients of modification coefficients were determined considering coherent parameters. The high precision model of backup roller diameter ef