Die Face Design Research Articles

Intelligent template based die face design method for process reuse of automotive panel

Die face design of automotive panel is a tedious repeated process and depends heavily on experience of engineers, which leads to increase of lead time and production costs. An intelligent template based die face design method is presented for process reuse of automotive panel. In this method, the new part is extracted as feature parameters to match the existing process in the template library automatically and the similar process model is applied to the new part adaptively. Finally, a process reuse system for die face is developed and a typical automotive panel is employed to verify the effectiveness of the proposed method. The results show a favourable effectiveness and practicability in reducing design period and reliance on experience.

Stamped part classification and automatic dieface design

In the context of weight reduction for new car design, it is essential to downsize, or rather optimize, the Body In White (BIW) structure. A very effective approach is to take into account the influence of Manufacturing process in the performance analysis such as crash or fatigue. Further, integrating the interaction between Stamping and Crash performance should also improve the predictability of the CAE approach and lead to more efficient design. One-step simulation of sheet metal forming is a very promising technology for this application, as it can be used on the same mesh as crash analysis and can work with a simplified dieface. However, a Dieface, although simplified, must be generated for nearly all parts of the vehicle model. Hence, the implementation of product-process coupling on an industrial scale requires the development of methodologies for automatic dieface design imbedding sheet metal forming expertise. Dieface generation depends on the geometrical features of the part, but we understand the latter only if we have a framework in terms of dieface features. The authors show that such a development requires an innovative approach to stamped part classification, based both on the geometrical features of the part and on the possible strategies in dieface development. Beside its novelty, this classification has the advantage of using a decision tree based only on a vector of quantitative features, thus making it possible to implement it in automatic decision support software. An application based on a real world BiW is presented.

On the die face design for stamping an automotive engine hood

Since the engine hood is mainly manufactured in the drawing operation, the die addendum design is the key to the success of manufacturing a defect free product. In this study, the existing die addendum designs corresponding to those engine hoods were reviewed and the design parameters were constructed. The preliminary study was then performed to examine the influences of the stamping die angle, binder surface shape, and die open line shape on the defects occurred in the part. Based on the simulation results, the optimum design for the die addendum face was then investigated and a systematic design guideline was proposed. In order to validate the proposed design guideline, actual engine hoods were stamped according to the finite element analysis and the production part shapes, thickness distributions, and the stretch at the central region were compared with those obtained from the finite element simulations. The consistent agreement between the product parts and the simulation results confirms the validity of the design guideline proposed in the present study for stamping an engine hood.

Formability Evaluation of 3D Closed Section Parts from Sheet Metal Based on Geometrical Information

For successful sheet metal forming, a complex design and trial process are inevitably necessary. That complex process is geometrical design, forming process selection, tool / die face design and forming condition. It may take couple of months to carry out this process, and at the end of this process try out may result in unsuccessful. The cause of this unsuccessful try out is difficult to find out because of the complexity of the design and try out process. It is proposed that a new evaluation methodology can provide semi-quantitate evaluation for the forming difficulty of the sheet. The proposed method evaluates only geometry of sheet metal parts, starting with Riemann curvature, which is decomposed into Gaussian curvature and metric tensor. Because the nature of sheet metal forming failure (breakage and wrinkle) are mainly related to in-plane deformation and not so much related to out of plane bending. Gaussian curvature is an excellent index for in-plane deformation caused by geometry angulation. Metric tensor provide quantitative evaluation for in-plane deformation. Computational time for this proposed method is a couple of minutes and is suitable for the evaluation and modification of the upstream design.

Spring-Back Control in Automotive Door Inner Panel Stamping

The spring-back defect of the front door inner panel is a major technical issue during the automotive body manufacturing processes. The primary purpose of this study is to control the spring-back value of the door inner panel by optimizing geometric parameters of addendum surface and selecting appropriate forming process. The Inverse Approach is employed to analyze the formability of the panel and to acquire rapid amendment of the die face design. Two kinds of forming processes are conducted, respectively, one-step forming method and two-step forming method. The results show that the one-step forming process combining with the optimized addendum surface can reduce the spring-back amount of side wall regions on door panel less than 2mm. The proposed optimizing scheme was verified by multiple trial-producing.

Precise Die Face Design of Drawing Dies for Stamping Process Based on Point Cloud

Low cost, short cycle and high quality are the goals of the automobile manufacturing. The auto die is one of the key equipments in automobile industry. For the die manufacturing process is very complicated the trial-and-error method is still used in the tryout process especially the die face tryout. The computer aided engineering becomes more and more important for the new die development. In this paper the precise die face design process based on the blank drawing and die structure simulation for automobile die is studied in detail. The precise die face is generated by the cloud of simulation nodes distribution. The industrial application shows that the precise die face design method based on point cloud generation for automobile die is an efficient way for decreasing the die manufacturing cycle and an accurate method for die tryout process.

Concurrent Engineering in the Application of Automobile Covering Parts Mould Development

Describe an advanced design and manufacturing technology Concurrent Engineering (CE) and give the automobile covering parts mould development flow basing on concurrent engineering. It tries to consider initially all factors of the mould development life cycle. Take an automobile covering part for example. Basing on the finite element analysis software AUTOFORM, do die design and forming simulation. According to the result of simulation, designer can predict the defect of forming and timely modify the forming process. So in stage of process design taking into account the blank forming, this kind of concurrent design of the mould surface can be directly used to mould design, also won't return after the mold design to modify the die-face design process. So on account of concurrent engineering, it can reduce the changes of automobile covering parts mould design and the number of repeated test, improve quality, reduce cost, and shorten the cycle of mould development.

The Full Flow of Precise Die Face Design Process for Automobile Die

The die manufacturing is very important for the automobile industry. For the die manufacturing process is very complicated the trial-and-error method is still used. In this paper the full flow of precise die face design process for automobile die is studied in detailed. First the primary drawing die face layout is explained. And the initial information for blank formability simulation and primary die surface design is summarized. For the precise die face design process the blank thinning rate and die deformation are studied according to the two simulation results combined. The industrial application shows that the full flow of precise die face design process for automobile die is a good way for decrease the die manufacturing cycle.

Research on the Application of Expansion Ratio Analysis for Die-Face Optimal Design in Sheet Metal Forming

In deep drawing process, the experimental approach to obtain proper die-face design is not only expensive, but also requires much time and effort. Numerical simulation of the die-face design using expansion ratio analysis (ERA) can provide an avenue for lowering the cost and increasing the speed of the design process. A finite-element model of four-node quadrangle element is developed based on static implicit method using the Finite Element Code Marc. By the use of the model, the die-face design of oil pan deep drawing process is simulated. The relationship between the ERA and the maximum thickness variation is obtained. The smaller the ERA, the smaller the maximum thickness variation can be acquired. The mission success rate of the forming process increases, too. All the simulation results show reasonable agreement with the experiment.

차량용 열차단판의 면품질 개선을 위한 성형해석 기반 금형면 설계

This paper concerns the die face design for a heat protect panel aided by the finite element forming analysis in order to eliminate the surface defect and to improve the surface quality. The CAE procedure of the stamping process is introduced in order to reveal the reason of surface inferiorities and to improve surface quality. Complicated shape of the product induces the surface inferiorities such as wrinkling due to the insufficient restraining force of the forming blank and the non-uniform contact of the blank with the tools. This paper proposes a new guideline for the die design which includes the modification of tool shapes and addition of the draw-beads on the tool surface for ensuring the increased the restraining force with the uniform contact condition. The effectiveness of the proposed design is verified by the forming analysis and is confirmed by the tryout operation in the press shop. The analysis and test results show that the modified process parameters such as tool shapes and draw-beads can reduce the tendency of wrinkling and improve surface quality.

Multi-objective optimization of an auto panel drawing die face design by mesh morphing

In order to facilitate the tryout or simulation process at the end of a manual auto panel drawing die face design process, we use finite element analysis (FEA) and a multi-objective genetic algorithm (MOGA) to find all the Pareto optimal solutions in one go and to achieve the optimal design of an auto panel drawing die face instead of transforming multi-objective functions into a single objective function, and employ a novel mesh morphing technique to achieve fast modification of parametric or non-parametric addendum surfaces and binder surfaces on drawing die faces without going back to CAD for reconstruction of geometric models or to FEA for remodeling. We use an auto panel drawing die face design process as an example to illustrate the application and effectiveness of this proposed approach, and come to the conclusion that the proposed approach is more effective than the traditional manual FEA method and the ‘trial-and-error’ approach in optimizing an auto panel drawing die face design.

Computer aided analysis and design of sheet metal forming processes:: Part III: Stamping die-face design

The finite element simulations of a sheet metal forming process help the methods and tooling engineer designing the forming interface for a stamping part by shifting the costly press shop try-outs to the computer aided design environment. The finite element models used in the sheet metal formability and stamping feasibility assessment studies are commonly based on the ideally rigid die-face design. This hypothesis is in general consistent with the present industrial experience even for large draw-dies of conventional steels. Nevertheless, it may not be practicable in the case of the forming high strength steels of moderate thickness because of the comparable higher press loads required to shape the blank. Consequently, an estimation of the die-face deformations during the forming process may be necessary during the evaluation of potential formability and springback problems and possible compensations should be considered in connection with the usual stamping die design and construction routines before submitting to the production. In this part of the study, an engineering methodology is presented for the structural assessment of the stamping tooling and the die-face designs during the sheet metal forming processes. Using the computer aided analysis and design concepts given previously in Part I and in Part II of this study, the proposed approach is employed in the forming interface design of an automotive stamping part including the complete die construction. The results have indicated the relative merits of the die-face distortions on the formability and springback deformations.

Computer aided analysis and design of sheet metal forming processes: Part I – The finite element modeling concepts

The design of a stamping die essentially begins with the geometric development of die-faces using the process specifications in the form of part geometry, material data and stamping criterion such as the thinning limits. Succeeding the completion of the forming interface geometry; the computer aided design models for the punch, the die and the binder tools are generated using the specifications of the manufacturing tools and presses. Nevertheless, an ensuing forming interface geometry is hardly possible right at the first time, and depending on the experience and skills of the methods engineer, several iterations may be required to ensure a die-face design that deforms the blank in to the stamping part at a minimum number operation. It is hence the design for the forming interface that determines a significant part of the tooling design and production costs. The computer aided analysis based on the finite element method may, on the other hand, help the stamping methods engineer to reduce the costly trial-and-error iterations through the qualification of the sheet metal forming process in accordance with the objective stamping criteria. In order to make an utmost benefit of computer analysis in the tooling design for stamping processes, the stamping engineer should have the fundamental understanding of the computational concepts of the finite element analysis in the sheet metal process simulation. The finite elements, the deformation response of sheet metals, and the numerical procedures are key concepts for the stamping simulation engineer in this perspective. The finite element procedures and the element formulations, along with their performance comparisons in an industrial stamping applications are the subjects in this part of the study. The sheet metal deformation modeling and the die-face design concepts are presented in Parts II and III, respectively, together with a set of industrial applications. The practical connotations of the computer aided analysis and design of the sheet metal stamping dies is given and conclusions are drawn.

DESIGN OF AUTO-BODY PANEL ADDENDUM BASED ON SWEEP SURFACE

Making the addendum and blank-holder surface is key technique in auto-body panel stamping and die-face design and machining. A great number of experiments and numerical simulation based on CAE have fully validated that the shape and configuration of the addendum and blank-holder surface have obvious influence on the formability of the stamped panel. In the past design of the panel die, users design them by hand- craft scheme and based on their old design experience, which evidently decreases design efficiency. A design scheme of the addendum and blank-holder surface, which is based on sweep surface design method and can efficiently solve some troubles on making the addendum is proposed. Besides, the creating ideal and constructing scheme of the sweep surface design are introduced, and their relative algorithms are proposed in terms of the forming features of auto-body panels. The feasibility of the constructing scheme is explained from actual industrial forming examples. Compared with the creating scheme based on FE meshes used in some CAE software, the most advantage of the present method is that the addendum and blank-holder surface created by sweep surface scheme can be directly used in DNC machining; and in the same time, many automatic and self-adaptive design processes based on the present algorithm can obviously increase design efficiency on auto-body panel die-face.

Expansion ratio analysis for initial die-face design of panel drawing dies

When the initial die-face of panel drawing dies is designed, the method of expansion ratio analysis (ERA) is usually employed to carry out formability analysis. Traditionally, ERA is performed with the help of geometry and experiential knowledge. Inevitably, design results differ from each other to the extent designers’ experiences vary. This is a rare work in which the authors research ERA by means of numerical simulations and experiments. Some useful rules are found, which can guide engineers in designing the initial die-face of panel drawing dies. ERA is less accurate than numerical simulation. As it locates upriver of panel dies development, its effect is significant. If the initial die-face is found to be acceptable after ERA, the efficiency and accuracy of numerical simulation can be improved greatly in designing the fine die-face and forming process.

Application of integrated formability analysis in designing die-face of automobile panel drawing dies

The die-face design of panel drawing dies is a creative process design procedure for a 3D panel product model. It includes determining the pressing direction, and designing the addendum, the binder surface, the drawbead, the die round, etc. The main goal of die-face design is to satisfy the need of drawing formability, but inherent in panel drawing forming are complicated mechanical problems. Among these are geometric non-linearity, material non-linearity and the non-linearity of process boundaries. Every factor affects every other factor to multiply the difficulties. Accordingly, the traditional experiential method and single computer-aided technology are inadequate. However, integrated formability analysis can solve these problems. Formability analysis is first done geometrically with 3D CAD software. Then two-stage fuzzy synthetic evaluation tests of die-face design are conducted. Finally, sequential FEM numerical simulation, considering synthetically geometry, material, process and other factors, completes the task. Thus integrated formability analysis makes full use of 3D CAD software, expert experience and FEM numerical simulation, and evolves progressively from simplicity to complexity, to satisfy the demands of the drawing process.

Swept Surface Synthesis With Visibility

The visibility of a surface has wide applications in manufacturing, where accessibility of the workpiece to the processing agent is of critical importance. A surface is visible to a direction d if for every point on the surface a line-of-sight can be established along d. Important applications, such as die-face design, arise in manufacturing where surfaces must be constructed visible to a given direction. In this paper we present a family of swept surfaces with built-in visibility. In particular, methods are laid out to build translational, rotational and spined sweeps visible to a given direction by sweeping monotone section curves. In these methods, minimal limitations are imposed besides those needed to avoid surface singularities. To increase modeling flexibility, the methods are extended to sweeps with distinct end sections and nonuniform scaling functions. [S1087-1357(00)00103-9]

Optimization of Tool/Workpiece Orientation in Designing Die-Face of Automobile Outer Panels

A procedure has been developed to optimize the product's tipping position, that is the relative orientation of the product surface with respect to the punch direction in a die, in designing a die-face for the manufacture of automobile outer panels. The two design requirements that are considered in optimizing the tipping position are: to satisfy that all points on the product have the most uniform drawing depths and to guarantee that the user-specified area on the product should contact initially with the binder wrap prior to other regions. The problem to solve when satisfying the design requirements described above is analogous to the flatness calculation problem in the area of metrology if some constraints can be imposed. Thus the problem can be solved by the simulated annealing method, which is one of the optimization methods. The developed procedure was applied to an actual die-face design and the results showed that the procedure was useful through the distribution diagram of the drawing depths.