Variable Blank Holder Force Research Articles

Sheet Stamping Formability Test System based Servo Crank Press

Proposed the tentative plan that carries on the formability test by simulation practical crank punch press slide speed characteristic, designed the solution to the implementation difficulty, and has carried on the actual attempt. The servo motor drive crank press speed alters at more sects which can get slider speed characteristic coherent with crank press varies. The system can test varies stamping formability that speed changeable based on sine curve. The system is composed of 600kN servo crank press, double action and all-purpose moldbase, date get and inspect analyze system. The moldbase adopted positive direction structural and self-motion, with variable blank holder force and counterforce controlled by hydraulic system with closed loop. The blank holder force can be set up in 5 sects which following with slide position, shortest control sect in 200ms. Appropriate profile of blank holder force can setup with the process needed. Blank holder has quartz force sensor which can inspect blank holder force and the control precision is in 0.1kN.

Optimization of initial blank shape for square cup deep drawing using variable blank holder force

Optimization of initial blank shape for square cup deep drawing using variable blank holder force

2102 角筒深絞り加工を対象とした初期ブランク形状と可変ブランクホルダー力の最適設計(OS5-3 設計と最適化3)

In deep drawing, area above the trimmed line is called earing. Reduction of the earing is one of the major issues for cost reduction. In addition, it is well known that blank holder force (BHF) has a direct influence on the product quality. A high BHF causes tearing, while a low BHF leads to wrinkling. Therefore it is important to determine an appropriate BHF through drawing. Recently, variable BHF (VBHF) approach which varies through the punch stroke has received a lot of attention, and its validity is discussed. In this study, both initial blank shape minimizing the earing and VBHF trajectory are simultaneously determined under tearing/wrinkling constants. In particular, two objective functions are defined for evaluation the earing. In other words, our design problem is formulated as a multi-objective design optimization. First objective function is the area above the trimmed line, and second one is the area below the trimmed line. In general, numerical simulation in sheet forming is so expensive that a sequential approximate optimization (SAO) using the radial basis function (RBF) network is adopted to identify the Pareto-frontier. The validity of the proposed approach is examined through numerical simulation. It can be found from the numerical result that earing is drastically reduced by the proposed approach.

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可変ブランクホルダー力の同時最適化

2115 角筒深絞り加工を対象とした初期ブランク形状と可変ブランクホルダー力の同時最適化(エネルギー・加工)

2115 角筒深絞り加工を対象とした初期ブランク形状と可変ブランクホルダー力の同時最適化(エネルギー・加工)

Influence of variable blank holder force on the formability of tailor-welded blank with different thickness

Influence of variable blank holder force on the formability of tailor-welded blank with different thickness

The U-Bending Forming of Aluminum Foam Sandwich Panels

The U-bending process of aluminum foam sandwich (AFS) is investigated, and a punch bending test is carried out in this paper. We discussed the bending deformation mode and generated the load & stroke curve of AFS panel by experiments. Macroscopic and microscopic punch forming mechanisms of AFS panels are analyzed by testing experiments and plasticity theory. We study the major deformation defects of AFS forming such as the delamination between the panel and the foam core, the excessive thinning of panels in the round corner, and shear stress cracks of the foam core. A conclusion is drawn on the panels variable blank holder force (VBHF) and the striking block control on the round corner, which would promote the forming technology of AFS.

Springback reduction with control of punch speed and blank holder force via sequential approximate optimization with radial basis function network

This paper proposes a springback reduction technique with the control of punch speed and blank holder force (BHF) via sequential approximate optimization (SAO). Springback is one of the major defects in sheet forming and its reduction is a crucial issue for improving product quality. Computer-aided-engineering is one of the helpful tools for predicting springback and widely used in automotive industries. Various approaches are considered for springback reduction, and we optimize the punch speed as well as BHF (variable BHF). Sheet forming simulation is generally costly and time-consuming, and the SAO with the radial basis function network is used to determine the optimal punch speed and variable BHF. The U-shaped forming in NUMISHEET’93 is used in the numerical simulation. The standard deviation of the bending moment is minimized subject tearing evaluated with the forming limit diagram. The punch speed and the variable BHF are taken as the design variables. The validity is examined through numerical simulation.

1309 逐次近似最適化を用いた可変ブランクホルダーカの軌道と工具モーションの同時最適化

In this paper, variable blank holder force (VBHF) trajectory and tools motion are optimized simultaneous by a sequential approximate optimization (SAO) with radial basis function (RBF) network. In deep drawing, wrinkling and tearing are major defects that are strongly avoided in sheet forming. These defects are then taken as the objectives directly. The Forming Limit Diagram (FLD) is employed to evaluate the risk of wrinkling and tearing quantitatively. The design variables are taken so as to optimize the VBHF trajectory and the tools motion simultaneously. In numerical examples, a square cup deep drawing is handled. The optimum result shows that simultaneous optimization of the VBHF trajectory and the tools motion result in the successful deep drawing. In particular, the forming energy can be drastically reduced, in comparison with only the optimization of VBHF trajectory. This result implies that the simultaneous optimization of both VBHF trajectory and tools motion will be effective approach to reduce the forming energy.

1914 多目的逐次近似最適化を用いた可変ブランクホルダーカの最適軌道設計

1914 多目的逐次近似最適化を用いた可変ブランクホルダーカの最適軌道設計

Development of a hydroforming setup for deep drawing of square cups with variable blank holding force technique

Sheet hydroforming is a process that uses fluid pressure for deformation of a blank into a die cavity of desired shape. This process has high potential to manufacture complex auto body and other sheet metal parts. Successful production of parts using hydroforming mainly depends on design aspects of tooling as well as control of important process parameters such as closing force or blank holding force (BHF) and variation of fluid pressure with time. An experimental setup has been designed and developed for hydroforming of square cups from thin sheet materials. Square cups have been deep drawn using constant and variable BHF techniques. A methodology has been established to determine the variable BHF path for successful hydroforming of the cups with the assistance of programmable logic controller and data acquisition system. Finite element (FE) simulations have also been carried out to predict formability with both of these techniques. It has been found that it is possible to achieve better formability in terms of minimum corner radius and thinning in the case of variable BHF technique than in the case of constant BHF technique (constant force during forming and calibration). The results of FE analysis have been found to be in good agreement with experimental data.

Optimization of variable blank holder force trajectory for springback reduction via sequential approximate optimization with radial basis function network

Springback is one of the major defects in sheet metal forming. Variable blank holder force (VBHF) approach is one of the effective ways for the springback reduction. In this paper, the VBHF trajectory is optimized to reduce the springback by a sequential approximate optimization (SAO) with radial basis function (RBF) network. The U-shaped forming in NUMISHEET'93 is employed to determine an optimum VBHF trajectory, for example. In this paper, the bending moment is taken as the objective function. The tearing of sheet during the forming is considered as the design constraint, and the forming limit diagram (FLD) is employed to evaluate the design constraint quantitatively. It has been found from numerical results that the optimal VBHF trajectory can drastically reduce the springback in comparison with various VBHF trajectories. Through the theoretical examination and numerical simulation, the springback reduction of metal forming by the VBHF trajectory is discussed.

Study on Blank Holder Force Control in Sheet Metal Forming Process

BHF is an important technical parameter in sheet metal forming, its main function is controlling material flowing，avoiding wrinkling and fracture. The status of study on the control technology of variable blank holder force (VBHF) was summarized, focusing on the method of optimized controlling and the theory of developing trend of VBHF is introduced in the paper.

Research on Deep Drawing with Multi-Point Variable Blank-Holder Force Controlling by Computer

On the basses of analyzing the defects of variable blank holder force hydraulic press on construction and its rigid being not enough,the realization of designing method,working principle,hydraulic and system for ne controlling w type upper multi-point deep drawing with variable blank—holding force controlled by computer was introduced.In order to verify the effect of application of this set up,the testing results of deep drawing a rectangular box and a cylindrical cup formed component was presented. The results show that the equipment has low cost, general in using and optimal efficient of controlling.

Optimization of Initial Blank Shape with a Variable Blank Holder Force in Deep-Drawing via Sequential Approximate Optimization

Optimization of Initial Blank Shape with a Variable Blank Holder Force in Deep-Drawing via Sequential Approximate Optimization

1209 スプリングバック抑制を目的とした可変ブランクホルダー力の最適軌道設計(OS7-2 近似最適化II)

Springback is one of the major defects in sheet metal forming. Numerical simulation based on finite element analysis is a powerful tool for springback prediction. Variable blank holder force (VBHF) approach is one of the effective ways for the springback reduction. In this paper, the VBHF trajectory is optimized by a sequential approximate optimization (SAO) with radial basis function network. U-shaped forming is handled for determining an optimum VBHF trajectory. In general, three objective functions are formulated in the springback reduction. These objective functions are not considered the state of the blank. In this paper, the residual bending moment is taken as the objective function. In order to evaluate the constraint quantitatively, the forming limit diagram (FLD) is employed. The forming by VBHF trajectory can drastically reduce the springback in comparison with the forming with the constant blank holder force.

Optimization of Variable Blank Holder Force Trajectory for Springback Reduction

Springback is one of the major defects in sheet metal forming. Numerical simulation based on finite element analysis is a powerful tool for springback prediction. Variable blank holder force (VBHF) approach is one of the effective ways for the springback reduction. In this paper, the VBHF trajectory is optimized by a sequential approximate optimization (SAO) with radial basis function network. U-shaped forming is handled for determining an optimum VBHF trajectory. In general, three objective functions are formulated in the springback reduction. These objective functions are not considered the state of the blank. In this paper, the residual bending moment is taken as the objective function. In order to evaluate the constraint quantitatively, the forming limit diagram (FLD) is employed. In particular, the tearing is considered as the constraint. It can be found from numerical results that the residual bending moment is more effective than the maximum nodal displacement for the springback reduction. In addition, the forming by VBHF trajectory can drastically reduce the springback in comparison with the forming with the constant blank holder force.

Influence of Process Parameters on the Deep Cup-Drawing Process by Simulation

Cup drawing, besides its importance as forming process, also serves as a basic test for the sheet metal formability. To determine the optimum values of the process parameters, it is essential to find their influence on the deformation behaviour of the sheet metal. Based on the predicted thickness and stress distribution of the deep drawn circular cup and analysis of process parameters by LS-DYNA software in the paper, it is evident that the minimum thickness is at the punch radius, which was the danger zone for breaking. BHF is the main influence factor of a axi-symmetric cup, according drawing theory, the curve of the variable blankholder force (VBHF) we designed could improve the formability of sheet. Further, it is shown mold radius has the greater influence on the deep drawing of blank sheet.

Simultaneous Optimization of Variable Blank Holder Force Trajectory and Tools Motion in Deep Drawing via Sequential Approximate Optimization

Simultaneous Optimization of Variable Blank Holder Force Trajectory and Tools Motion in Deep Drawing via Sequential Approximate Optimization

CO-JP-4 Simultaneous Optimization of Variable Blank Holder Force Trajectory and Tools Motion in Deep Drawing via Sequential Approximate Optimization

CO-JP-4 Simultaneous Optimization of Variable Blank Holder Force Trajectory and Tools Motion in Deep Drawing via Sequential Approximate Optimization