The Influence of the Blank Holder Force during Forming Process of a U-Shaped Part Made from AZ31 Magnesium Alloy

2015 ◽  
Vol 809-810 ◽  
pp. 265-270
Author(s):  
Aurelian Albut ◽  
Valentin Zichil ◽  
Adrian Judele
Keyword(s):  
Magnesium Alloy ◽  
Sheet Metal ◽  
Elastic Recovery ◽  
Rolling Direction ◽  
Sheet Thickness ◽  
Bending Moment ◽  
Blank Holder Force ◽  
Forming Process ◽  
Blank Holder ◽  
Shaped Part

In case of sheet metal forming the main dimensional errors are caused by the springback phenomena. The present work deals with numerical simulation related to draw bending and springback of U - shaped part made from magnesium alloy. The current paper is trying to prove out the important role of the blank holder force with respect to the forming process. Though novel approaches relating to the formality of magnesium alloy sheets, the change of springback due to the characteristic of each process should be verified by finite element method. Springback refers to the elastic recovery of deformed parts. Springback occurs because of the elastic relief from the bending moment imparted to the sheet metal during forming. Springback is mainly influenced by the sheet thickness, the punch and die profile radii, initial clearance between punch and die, friction conditions, rolling direction of the materials, blankholder force and by material properties. In this study, the magnesium alloy strips with two types of material having the thickness of 1mm, are used to investigate springback characteristics in U-shape bending. The Dynaform 5.6 software was used to simulate the forming process, in which the blank holder force takes values between 15 and 35 kN. In this study, the springback was analyzed by U-forming at room temperature conditions with different blank holder forces. Springback decreased with the increase of the blank holding force. Excessive holding force cause irregular thinning of the material, especially in the radius area.

Study on Formability of Tailor-Welded Blank Based on Sheet Metal Matching

2010 ◽  
Vol 139-141 ◽  
pp. 618-621
Author(s):  
Jin Lun Wang ◽  
Feng Chong Lan ◽  
Ji Qing Chen
Keyword(s):  
Mechanical Properties ◽  
Sheet Metal ◽  
Weld Line ◽  
Blank Holder Force ◽  
Forming Process ◽  
Blank Holder ◽  
Shaped Part ◽  
Single Sheet ◽  
Tailor Welded Blank ◽  
Forming Defects

As tailor-welded blank having two or more sheet metal welded together, with different mechanical properties, coating and thicknesses, its yield strength and tensile strength are higher, but hardening exponent and elongation are lower than a single sheet. The different mechanical properties of substrates and weld movement have significant effects on TWB’s formability, different materials or thicknesses easily lead to uneven deformation and forming defects such as cracking, wrinkle and springback. This paper takes tailor-welded box-shaped part for example; the forming process and weld movement were simulated and analyzed. In this process, the weld type was ignored, only considering the weld-line position, using segmented blank holder to control the size of the blank holder force on both sides respectively. Three cases of sheet metal matching were carried out including: different thicknesses with same material, same thickness with different materials, and different thicknesses with different materials. Finally, some meaningful results were obtained.

Applying 2k Factorial Design to Study on Parameters Affecting Springback of Forming of Advanced High Strength Steel Sheets (AHSS)

2017 ◽  
Vol 872 ◽  
pp. 83-88
Author(s):  
Ramil Kesvarakul ◽  
Chamaporn Chianrabutra ◽  
Watcharapong Sirigool
Keyword(s):  
Elastic Recovery ◽  
Weight Ratio ◽  
High Strength ◽  
Die Design ◽  
Statistical Experimental Design ◽  
Blank Holder Force ◽  
Forming Process ◽  
Blank Holder ◽  
Punch Radius ◽  
Springback Angle

Advanced high strength steels (AHSS) are widely used in the automotive industry due to their appropriate strength to weight ratio. This alloy has unique hardening behavior and variable unloading elastic modulus; however, the unavoidable obstacle of AHSS sheet metal forming is springback. The springback is a result of elastic recovery and residual stress. The aim of this study is to determine the proper process parameters enabling the reduction of the springback defects in AHSS forming process. This work was divided into two parts, regarding to the effects of numerical parameters and process parameter on forming AHSS. In this paper, a U-shape forming was used to examine the springback behaviors, such as springback angle, sidewall curl, and thickness, through an experiment. To achieve this purpose, 2k factorial statistical experimental design has been employed to investigate the parameters affecting the springback of forming in AHSS to find out the main effect in the springback reduction focusing on using as a guideline for die design. It showed that the blank holder force is the most influential parameter. The second is the punch radius. However, the blank holder force and punch radius is not simple to adjust in die design, the die radius becomes the important parameter to be used to reduce the springback angle.

Thickness of Magnesium Alloy Cylindrical Cup in Pressure-Lubricating Deep Drawing

2012 ◽  
Vol 189 ◽  
pp. 147-151
Author(s):  
Xian Chang Mao ◽  
Hai Yan Lin
Keyword(s):  
Magnesium Alloy ◽  
Wall Thickness ◽  
Deep Drawing ◽  
Thickness Distribution ◽  
Blank Holder Force ◽  
Technological Parameters ◽  
Forming Process ◽  
Blank Holder ◽  
Deformation Behaviors ◽  
Cylindrical Cup

Forming process of AZ31B magnesium alloy cup parts in pressure-lubricating deep drawing was simulated by Dynaform at room temperature. The technological parameters which influence the wall thickness difference of cup parts were investigated in this paper, including internal pressure, blank holder force and punch corner radius, etc. Compared with the deformation behaviors of magnesium alloy in mechanical deep drawing and pressure-lubricating deep drawing, the wall thickness distribution of cup parts was discussed. The result shows that preferable deformation behaviors can be obtained in pressure-lubricating deep drawing when adopted adaptive technological parameters.

Estimation of Optimal Blank Holder Force Trajectories in Segmented Binders Using an ARMA Model

2003 ◽  
Vol 125 (4) ◽  
pp. 763-770 ◽  
Author(s):  
Neil Krishnan ◽  
Jian Cao
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Moving Average ◽  
Arma Model ◽  
Blank Holder Force ◽  
Forming Process ◽  
Blank Holder ◽  
Modes Of Failure ◽  
System Input

Sheet metal forming is one of the most important and frequently used manufacturing processes in industry today. One of the key parameters affecting the forming process is the blank holder force (BHF). In the past, researchers have demonstrated the advantages of varying the blank holder force during the forming process, that is, the two primary modes of failure in sheet metal forming (wrinkling and tearing) are avoided. This gives rise to improved formability, higher accuracy and better part consistency. In recent years, researchers have also shown increasing interest in forming processes where the blank holder force is varied spatially with the help of segmented binders or flexible binders. In this paper, we have combined the above two aspects and used a robust method to determine the blank holder force trajectories for a non-circular part using segmented binders. The proposed strategy is verified by implementing it into a finite element simulation. Binder force is treated as a system input. The displacement of the binder is used as a measure of the tendency to wrinkle, and is therefore treated as a system output. The parameters of the system are continuously identified and updated using a deterministic Auto-Regressive Moving-Average model (ARMA). The model is then used to control the binder displacement to a prescribed value by adjusting the system input, i.e., the binder force. In this manner, individual binder force profiles for each of the segmented binders are obtained. Due to the generic nature of the ARMA model, the strategy proposed in this paper can be applied to a variety of forming problems, making it a robust approach.

Study on Blank Holder Force Control in Sheet Metal Forming Process

2012 ◽  
Vol 182-183 ◽  
pp. 1605-1608
Author(s):  
Xiao Juan Lin ◽  
Jian Hua Wang ◽  
Ke Gao Liu
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Main Function ◽  
Blank Holder Force ◽  
Forming Process ◽  
Blank Holder ◽  
Variable Blank Holder Force ◽  
The Status ◽  
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.

The Impact Analysis of Stamping Process Factors Based on Dynaform

2013 ◽  
Vol 712-715 ◽  
pp. 642-646
Author(s):  
Zhen Gang He ◽  
Yan Ping Zheng ◽  
Gai Yan
Keyword(s):  
Quality Evaluation ◽  
Impact Analysis ◽  
Simulation Analysis ◽  
Blank Holder Force ◽  
Forming Process ◽  
Blank Holder ◽  
Stamping Process ◽  
The Coefficient Of Friction ◽  
Process Factors ◽  
The Impact

Combining with practical needs in production, it carried out the numerical simulation analysis of automobile beam stamping forming process based on Dynaform in this paper. According to quality evaluation index of forming parts, it analyzed the effect of variation of blank holder force, the stamping speed, the coefficient of friction and draw bead on stamping quality. It forecast the quality problems happened in forming process, which provides the theoretical basis for design of stamping process and mold.

Study of the Parameters of Deep Drawing Process Based on the Simulation of Dynaform

2012 ◽  
Vol 249-250 ◽  
pp. 51-58
Author(s):  
Qing Wen Qu ◽  
Tian Ke Sun ◽  
Shao Qing Wang ◽  
Hong Juan Yu ◽  
Fang Li
Keyword(s):  
Friction Coefficient ◽  
Sheet Metal ◽  
Deep Drawing ◽  
Drawing Process ◽  
Blank Holder Force ◽  
Blank Holder ◽  
Deep Drawing Process ◽  
Drawing Die ◽  
Drawing Speed

A simulation of deep drawing process on the sheet metal was done by using Dynaform, the influence of blank holder force, deep drawing speed and friction coefficient on the forming speed of sheet metal in the deep drawing process were got. The forming speed of sheet metal determines the quality of deep drawing, in the deep drawing process the blank holder force and the deep drawing speed are controllable parameters, the friction coefficient can be intervened and controlled, and it’s a manifestation of the interaction of all parameters, the main factors which influence the friction coefficient just have blank holder force, deep drawing speed and lubrication except the material. The conclusion of this study provides the basic data for the analysis of the lubrication of mould, the study of lubricant and the prediction of the service life of deep drawing die.

Research on the Finite Element Simulation of the Laser Shock Forming of TC4 Titanium Alloy

2016 ◽  
Vol 693 ◽  
pp. 1121-1128 ◽  
Author(s):  
Guo He Li ◽  
David Mbukwa ◽  
Wei Zhao
Keyword(s):  
Finite Element ◽  
Sheet Metal ◽  
Laser Energy ◽  
Sheet Thickness ◽  
High Amplitude ◽  
Laser Spot ◽  
Laser Shock ◽  
Forming Process ◽  
Element Analysis ◽  
Laser Shock Forming

laser shock forming, which combines the metal forming and material modification, is a non-mode, flexible forming new technology using laser-induced force effect of high amplitude shock waves to obtain the plastic deformation of sheet metal. in this paper, the simulation of laser shock forming process of tc4 sheet metal was carried out through the commercial finite element analysis software abaqus. the influence of the sheet thickness, laser energy, constraints aperture and laser spot spacing on the sheet metal deformation are investigated. the results show that: with the increase of sheet thickness, the deformation range of sheet decreases, and the amplitude of deformation decreases firstly and then increases. the deformation increases linearly with the increase of laser energy. the larger boundary constraint aperture leads to the larger deformation of sheet metal. there are no obvious influence on the forming accuracy when an opposite laser spot spacing is adopted. therefore, under the condition of meeting the accuracy requirement, for improving the efficiency, adopting a certain laser spot spacing to finish the forming should be considered.

The Effect of Anisotropy on Spring-Back of CK67 Steel Sheet in L-Dies Bending Processes

2011 ◽  
Vol 291-294 ◽  
pp. 672-675
Author(s):  
Jafar Bazrafshan ◽  
A. Gorji ◽  
A. Taghizadeh Armaky
Keyword(s):  
Numerical Simulations ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Steel Sheet ◽  
Elastic Recovery ◽  
Sheet Thickness ◽  
Bend Angle ◽  
Spring Back ◽  
Geometric Changes

One of the most sensitive features of sheet metal forming processes is the elastic recovery during unloading, called spring-back, which leads to some geometric changes in the product. This phenomenon will affect bend angle and bend curvature, and can be influenced by various factors. In this research, the effects of sheet thickness and die radiuses an sheet anisotropy on spring-back in L-die bending of CK67 steel sheet were studied by experiments and numerical simulations.

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