Optimal Blank Shape Research Articles

Automatic Optimization of Initial Blank Shape in Production of All Kinds of Rectangular Parts in Computer Aided Hydroforming Process

Automatic Optimization of Initial Blank Shape in Production of All Kinds of Rectangular Parts in Computer Aided Hydroforming Process

Optimization of process parameters for rectangular cup deep drawing by the Taguchi method and genetic algorithm

Abstract This article presents the optimization of process parameters in reducing the risk of failure due to wrinkling and fracture in deep drawing of a rectangular cup. Blank holder force, friction coefficient, punch radius and initial blank shape were chosen as design parameters. Wrinkling and fracture criteria were used as objective functions. Two-stage optimization approach was used. In the first stage optimization, optimum blank shape was determined using the Taguchi optimization method. In the second stage optimization, optimum parameter values were determined for the selected blank shape by the first stage optimization using genetic algorithm. In the second stage of optimization, response surface models based on 3-level full factorial design of experiments were constructed. Finite element simulation results were used for creating response surface models. Parameters obtained from optimization study were confirmed by conducting deep drawing simulations using commercial code DYNAFORM 5.9.2. Optimum results showed that proposed optimization methodology can solve wrinkling and fracture problems in the sheet metal forming process.

Optimum blank shape design in deep drawing process using a new boundary updating formula

Optimum blank shape design in deep drawing process using a new boundary updating formula

Blank Shape Optimization Considering 3D Space Targets for External and Internal Boundaries in Sheet Metal Forming Processes

Optimum design of the shape of the initial blank is an important task before sheet metal forming processes. It reduces production costs, material waste and improves the quality of the product significantly. In the present work, the blank shape optimization problem is considered based on the 3D space target contours and moreover the sheet metal can have an internal boundary. In other words, the shape optimization process can be applied on the internal boundary, external boundary or both. To the best knowledge of the authors, there are no published works in this subject. Using the iterative simulation-based optimization process, a special shape error index and also updating algorithm were proposed to modify the blank geometry in each iteration until capturing the optimum shape. The sheet forming process is highly nonlinear in nature due to plastic behaviors, large deformations and frictional contact surfaces. Therefore, the updating formula should be robust enough to have less sensitivity with respect to the initial guess. To evaluate the proposed updating formula and its robustness, some numerical examples were considered and the effects of different tools geometries, 2D and 3D target contours, internal and external boundaries and different initial guesses were examined.

Blank shape optimization in the deep drawing process by sun method

Deep drawing is one of the most important and widely used processes in industry for the production of various parts. In this process, the optimal design of the blank has many advantages such as reducing the cost of production and waste and improving the quality of the process and thickness distribution. In this study, blank optimization involves finding an initial blank geometry in which the edge contours of the final product approach a target contour, taking the required shape after deep drawing. A new iteration based method is proposing for optimizing the shape of a blank in the deep drawing process. The behavior in such problems is severely nonlinear as a result of major plastic deformations and contact phenomena. The general solution to such problems has been to use numerical simulation iterative based methods. The present study implements a similar approach and presents a new algorithm to make geometrical corrections to the external boundaries of a blank in several iterations. A computer program was developed to automatically run these iterations to study the features of the proposed method. Next, two numerical example was solved, and the results are compared with other studies. The proposed method is robust against the initial guess as it manages to optimize the blank regardless of it.

A Method for Simultaneous Optimization of Blank Shape and Forming Tool Geometry in Sheet Metal Forming Simulations

This paper presents a numerical method for simultaneous optimization of blank shape and forming tool geometry in three-dimensional sheet metal forming operations. The proposed iterative procedure enables the manufacturing of sheet metal products with geometry fitting within specific tolerances (surface and edge deviations less than 0.5 or 1.0 mm, respectively) that prescribe the maximum allowable deviation between the simulated and desired geometry. Moreover, the edge geometry of the product is affected by the shape of the blank and by an additional trimming phase after the forming process. The influences of sheet metal thinning, edge geometry, and springback after forming and trimming are considered throughout the blank and tool optimization process. It is demonstrated that the procedure effectively optimizes the tool and blank shape within seven iterations without unexpected convergence oscillations. Finally, the procedure thus developed is experimentally validated on an automobile product with elaborated design and geometry which prone to large springback amounts owning to complex-phase advanced high strength steel material selection.

Numerical optimization of blank shape and sloped variable blank holder force tarjectory for an automotive part

Numerical optimization of blank shape and sloped variable blank holder force tarjectory for an automotive part

Numerical optimization of blank shape and sloped variable blank holder force trajectory for an automotive part

Numerical optimization of blank shape and sloped variable blank holder force trajectory for an automotive part

Optimization of initial blank shape for flexible micro deep drawing of square parts

Micro flexible tool-assisted sheet metal forming is one of the forming techniques that have increasingly attracted extensive attention of researchers. Due to its simplicity, low overall production cost, feasibility of prototyping, this forming process seems appropriate for producing micro components. This work presents an evaluation study on using flexible deep drawing process to produce micro stainless steel 304 square cups. The influence of initial foil thickness and blank shape are investigated in details. An optimization of blank shape is implemented to provide micro square products with net-shape and flange free. The finite element simulations are achieved using the commercial code Abaqus/Standard. The results showed that the initial foil thickness affects the thinning and thickening values of the formed cup wall. As well as, the optimization method is feasible to indicate the optimum initial blank shape for producing free flange- micro square parts.

Blank layout shape optimization of drawn part

Blank layout shape optimization of drawn part

Numerical optimization of variable blank holder force trajectory and blank shape for twist springback reduction using sequential approximate optimization

This paper proposes an approach for twist springback reduction using variable blank holder force (VBHF) trajectory that the blank holder force (BHF) varies through the stroke. In addition, the blank shape is optimized. Therefore, design optimization of VBHF trajectory and blank shape for twist springback reduction is performed. Springback of U-shaped product is a simple deformation, whereas the one of S-rail-shaped product shows more complicated behavior due to twisting. As the result, compared with the springback of U-shaped product, it is difficult to evaluate the twist springback. A novel evaluation method for the twist springback is proposed, and the optimal VBHF trajectory and blank shape for the twist springback reduction are determined under several design constraints. Numerical simulation of the S-rail-shaped product is so intensive that response surface approach is valid. In particular, a sequential approximate optimization that the response surface is repeatedly constructed and optimized is used to determine the optimal VBHF and blank shape. Through numerical result, the validation of the proposed approach is examined.

Optimization of Initial Blank Shape for Minimizing the Trimming Process in Hot Stamping of T-Shaped Parts

Blank optimization in stamping is a way to reduce the cost of unnecessary material consumption or subsequent trimming operations by acquiring the final target part in a single forming process. There have been many studies on blank optimization in room temperature stamping, but few studies have yet been conducted in hot stamping. In this study, a blank shape optimization was conducted for a T-shaped part simulating a body center pillar. A finite element analysis (FEA) for the hot stamping process was performed using an appropriately assumed initial blank shape, and the blank shape was updated based on the shape error between the outline of the deformed blank obtained from the FEA and that of the target part. The shape error was calculated by applying the modified radius vector method. Hot stamping test was carried out using the optimal shaped blank predicted by the FEA. It was confirmed that the outline of the deformed blank obtained by the actual test was very close to the outline of the target part. From the results of this study, it can be seen that the blank optimum design technique at room temperature stamping can be applied to the case in hot stamping.

Design optimization of variable blank holder force trajectory and blank shape for S-rail shaped product using a novel springback evaluation

Design optimization of variable blank holder force trajectory and blank shape for S-rail shaped product using a novel springback evaluation

深絞り加工におけるブランク形状と分割可変ブランクホルダー力の同時最適化

深絞り加工におけるブランク形状と分割可変ブランクホルダー力の同時最適化

深絞り加工における耳最小化を目的とした初期ブランク形状と分割可変ブランクホルダー力の同時最適化

深絞り加工における耳最小化を目的とした初期ブランク形状と分割可変ブランクホルダー力の同時最適化

Optimization of blank shape and segmented variable blank holder force trajectories in deep drawing using sequential approximate optimization

Blank holder force (BHF) is one of the important process parameters for successful sheet metal forming. Variable blank holder force (VBHF) that the BHF varies through the forming process is recognized as an advanced forming technology. It has also been reported that segmented VBHF (S-VBHF) is valid to a complex shape forming, but the optimal S-VBHF trajectories are rarely discussed and used. In addition to BHF, blank shape has an influence on the product quality. The blank shape minimizing the earing is still an important issue in sheet metal forming. Simultaneous optimization of both S-VBHF trajectories and blank shape is one of the crucial issues in industries. This paper proposes a method to simultaneously optimize both the segmented VBHF trajectories and the blank shape. Numerical simulation in sheet metal forming is so intensive that a sequential approximate optimization (SAO) using a radial basis function (RBF) network is adopted for the simultaneous design optimization. Based on the numerical result, the experiment using the AC servo press (H2W300, Komatsu Industry Corp.) that can conduct the optimal S-VBHF trajectories is carried out. It has been confirmed from the numerical and experimental result that the proposed approach is valid.

Simultaneous optimization of blank shape and variable blank holder force of front side member manufacturing by deep drawing

This paper presents a method to determine an optimal blank shape minimizing earing for a front side member. In addition, variable blank holder force, meaning that the blank holder force (BHF) varies through punch stroke, is adopted. Blank shape directly affects the material cost, and it is important to determine an optimal blank shape minimizing earing that is trimmed out. BHF also have an influence on the product quality. Large BHF leads to tearing, whereas small BHF results in wrinkling. Variable BHF (VBHF) approach is recognized as one of the advanced manufacturing technologies, but it is difficult to determine the optimal VBHF for successful sheet metal forming. To determine the optimal blank shape and VBHF simultaneously, design optimization is performed. Numerical simulation in sheet metal forming is so intensive that a response surface approach is valid. In particular, a sequential approximate optimization that the response surface is repeatedly constructed and optimized is used to determine the optimal blank shape and VBHF. Front side member provided from NUMISHEET 2011 (BM3) is used for the numerical simulation. It is found from the numerical result that the proposed approach can drastically reduce the earing. In addition, the maximum thinning is much improved, compared with other results reported in NUMISHEET 2011.

Genetic Algorithm optimization of initial blank shape in deep drawing of a stepped work piece

This study considers the effect of forging direction on the initial shape of sheet to create a stepped work piece. The purpose of this study is to consider rolling direction in 0°, decreasing the waste while producing workpieces and so decreasing total cost of process. To this end, the assumed workpiece was made of a low carbon and anisotropic st14 steel sheet. To find the most appropriate direction and the shortest modification steps for final shape, the expansion level of the sheet was first imaged in the rolling direction and then the piece was shaped by the geometry. This approach was based on the coupling between the simulation and Genetic Algorithm. A Genetic Algorithm based approach is developed to optimize dimensions through integrating a finite element code running to compute the objective functions for each generation. Those points with a few materials modified through Genetic Algorithm yielded better results.

Optimum Blank Shape for Cylindrical Cup from SUS304 in Deep Drawing Process by Finite Element Method

The deep drawing process is used in many industries, such as customer goods, automotive and electronics, etc. In the production of perfect workpieces, there are some problems that occur during the production, for example, there can be an earing defect during the deep drawing process of cylindrical cups, etc. The earing is cut before use, and this means the production cost must increase. This research studied how to reduce the earing by modifying the blank shape to get the lowest earing height. There were three shapes of the blank sheet studied in this research: the original blank shape, the blank shape modified by Zaky’s theory and the blank shape modified by Kumar’s theory. The studied material was SUS304 stainless steel with a 1 mm thickness. The results show that the blank shape from Zaky’s theory caused the least earing defect. The percentages of the earing heights occurring from the blank shape from Zaky’s theory, the blank shape from Kumar’s theory and the original blank shape were 3.93%, 5.21% and 5.66%, respectively. The rolling direction of those three shapes at 45 degrees caused more earing than at 0 and 90 degrees.

Numerical and experimental case study on simultaneous optimization of blank shape and variable blank holder force trajectory in deep drawing

This paper shows a case study for a simultaneous optimization of blank shape and variable blank holder force (VBHF) trajectory in deep drawing, which is one of the challenging issues in sheet metal forming in industry. Blank shape directly affects the material cost. To reduce the material cost, it is important to determine an optimal blank shape minimizing earing. In addition, VBHF approach is recognized as an attractive and crucial technology for successful sheet metal forming, but the practical application is rarely reported. To resolve these issues, the simultaneous optimization of blank shape and VBHF trajectory is performed. First, the experiment to identify the wrinkling region is carried out. Based on the experimental results, the finite element analysis (FEA) model is developed. The validity of the FEA model is examined by using the FLD. Numerical simulation in deep drawing is so intensive that a sequential approximate optimization (SAO) using a radial basis function (RBF) network is used for the numerical optimization. Based on the numerical result, the experiment using the AC servo press is carried out. It is found from the experimental results that the successful sheet metal forming is performed. In addition, it is confirmed from the numerical and experimental result that both the material cost and the forming energy are simultaneously reduced by using the design optimization technique.