Effect of Variable Blank Holder Force on the Springback and Weld-Line Movement During Draw-Bending of Tailor Welded Blanks

2015 ◽  
Author(s):  
Bishoy M. Dawood ◽  
Mostafa Shazly ◽  
Abdalla S. Wifi ◽  
Alaa El-Mokadem
Keyword(s):  
Finite Element ◽  
Weld Line ◽  
Bench Mark ◽  
Blank Holder Force ◽  
Blank Holder ◽  
Tailor Welded Blanks ◽  
Variable Blank Holder Force ◽  
Draw Bending ◽  
Weld Line Movement ◽  
Line Movement

Tailor welded blanks (TWBs) manufactured by drawing processes suffer from two major defects; weld-line movement (WLM) and springback. These defects can be reduced by using a counterpunch or controlling the value of the blank holder force and its scheme. This work presents a finite element analysis of the effect of variable blank holder force (VBHF) on springback and WLM of bench mark problem of draw-bending process of a TWB. The proposed VBHF scheme is developed based on the reaction forces predicted in a finite element model for artificially clamped weld-line case. The results obtained by applying VBHF are compared with those obtained using a counterpunch. The use of counterpunch is found to eliminate Vertical WLM in all the considered cases. Whereas side WLM using VBHF is found to be less than that obtained using counterpunch. When compared to the counterpunch technique, the springback values are found to be improved by applying the VBHF schemes.

Theoretical and experimental investigation of deep drawing of tailor-welded IF steel blanks with non-uniform blank holder forces

2016 ◽  
Vol 231 (2) ◽  
pp. 286-300 ◽  
Author(s):  
Mohammad Hossein Asadian-Ardakani ◽  
Mohammad Reza Morovvati ◽  
Mohammad Javad Mirnia ◽  
Bijan Mollaei Dariani
Keyword(s):  
Deep Drawing ◽  
Weld Line ◽  
Body Parts ◽  
Blank Holder Force ◽  
Blank Holder ◽  
Tension Distribution ◽  
Strip Drawing ◽  
Parts Manufacturing ◽  
Weld Line Movement ◽  
Line Movement

Tailor-welded blank is one of the promising technologies in the application of lightweight materials for auto body parts manufacturing. The material discontinuity across the weld line results in an inhomogeneous deformation and weld line displacement. In this study, a two-dimensional analytical model is proposed to predict the tension distribution along the cross section. An energy method is used to calculate the restraining force due to bending, sliding, and unbending phenomena on the die and punch radii. To control the weld line movement, a blank holder force control strategy is proposed to achieve force equilibrium at the bottom of the part across the weld line. Finite element simulations are performed to study the effect of die and punch radii, friction coefficient, thickness ratio, and blank holder forces on the weld line displacement in strip drawing process. Under a uniform blank holder force, the weld line moves toward the thicker/stronger side implying a higher blank holder force is required for the thinner/weaker side. The results show that the weld line displacement can be controlled by an appropriate blank holder force adjustment. In order to control the weld line movement in square cup deep drawing, blank holder force on the thinner side is increased and its influences on the deformation process are investigated. Comparisons of material draw-in, weld line movement, and forming force show a good agreement between the theoretical, numerical, and experimental results.

Formability Enhancement for Tailor-Welded Blanks Using Blank Holding Force Control

2003 ◽  
Vol 125 (3) ◽  
pp. 461-467 ◽  
Author(s):  
Sijun He ◽  
Xin Wu ◽  
S. Jack Hu
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Strain Distribution ◽  
Weld Line ◽  
Finite Element Simulations ◽  
Stress Strain ◽  
Tailor Welded Blanks ◽  
Blank Holding Force ◽  
Weld Line Movement ◽  
Line Movement

Tailor-welded blanks (TWB) are widely used for stamped auto body panels because of their great benefits in weight and cost reduction. However, the weld line in a tailor-welded blank causes serious concerns in formability because of material discontinuity and additional inhomogeneous stress/strain distribution. This paper proposes a blank holding force (BHF) control strategy to control the weld line movement, distribute the deformation more uniformly and thereby improve TWB formability. The control methodology is developed based on a simplified 2-D sectional analytical model that estimates the stress/strain distribution and the BHFs required for each side of the flange with dissimilar materials. The model can be further extended to 3-D analysis by superimposing the 2-D sectional analysis results around the entire binder ring and thus determining the required BHF for the whole panel. Finite element simulations are performed to study the effects of forming parameters on the weld line movement. Experiments have been conducted to verify the analytical model and partial finite element simulations. Both analysis and experiments demonstrated that a lower BHF should be applied on the thicker blank side to allow more metal to flow-in for obtaining more uniform strain distribution. The proposed BHF control is proven to be a good approach to enhancing TWB formability.

The Research of Forming Process Parameters Influence on the Square Cup of TWBs’ Weld-Line Movement

2014 ◽  
Vol 644-650 ◽  
pp. 4835-4839
Author(s):  
Yong Gan ◽  
Han Chao Wang ◽  
Ying Ying Guo
Keyword(s):  
Weld Line ◽  
Base Material ◽  
Thickness Ratio ◽  
Strength Ratio ◽  
Blank Holder Force ◽  
Forming Process ◽  
Blank Holder ◽  
Weld Line Movement ◽  
Lubrication Conditions ◽  
Line Movement

The forming process of the square cup of TWBs is studied through the numerical simulation by Dynaform, and combined with orthogonal test, analyzed the thickness ratio, strength ratio, weld-line position, total blank-holder force, the thinner side’s blank-holder rate and the friction coefficient’s relations with the square cup of TWBs’ weld-line movement during the stamping process, and using the BP neural network toolbox model to forecast the weld-line movement in the process of forming. Studies show that regardless of the thickness ratio impact on the bottom of the square cup or on the flange, weld-line movements are at the maximum, the strength ratio is the second. The smaller proportion of the thinner side of the base material, the lower weld-line movement is. Selecting the suitable thinner side and thicker side’s blank-holder, and the reasonable lubrication conditions can control the value of the weld-line movement.

Minimization of weld line movement in heat-assisted forming of tailor welded blanks

2018 ◽  
Vol 233 (11) ◽  
pp. 3760-3768
Author(s):  
VVN Satya Suresh ◽  
Srinivasa Prakash Regalla ◽  
Amit Kumar Gupta
Keyword(s):  
Weld Line ◽  
Tungsten Inert Gas Welding ◽  
Selective Heating ◽  
Tailor Welded Blanks ◽  
Stamping Process ◽  
Steel Aisi ◽  
Tailor Welded Blank ◽  
Weld Line Movement ◽  
Line Movement

In this work, the formability aspects in terms of desired cup height during stamping operation of tailor welded blanks have been studied along with minimizing the movement of weld line. Circular sheets were prepared by joining austenitic stainless steel (ASS 304 Grade) and drawing quality mild steel (AISI 1018) materials with tungsten inert gas welding. To reduce the undesirable weld line movement during stamping process, a novel heat-assisted forming method involving localized and controlled heating of the stronger material side (ASS 304 steel) has been carried out. The experimental setup developed for this purpose enabled heating and maintained the selected zone at the desired temperature during the stamping process. The entire process has been simulated using finite element method and the results obtained were in close agreement with the experimental results. The effect of selective heating of tailor welded blank also resulted in the overall improvement in the quality of the product.

Comparison of Analytical Model to Experimental Results and Numerical Simulations for Tailor Welded Blank Forming

2004 ◽  
Author(s):  
Matt Bravar ◽  
Brad Kinsey ◽  
Neil Krishnan
Keyword(s):  
Numerical Simulations ◽  
Analytical Model ◽  
Weld Line ◽  
Experimental Results ◽  
Forming Process ◽  
Tailor Welded Blanks ◽  
Industrial Utilization ◽  
Initial Placement ◽  
Weld Line Movement ◽  
Line Movement

Tailor Welded Blanks offer several notable benefits including decreased part weight, reduced manufacturing costs, and improved dimensional consistency. However the reduced formability and other characteristics of the forming process associated with TWBs has limited the industrial utilization of this blank type. One concern with TWB forming is that weld line movement occurs which alters the final location of the various materials in the TWB combination. In this paper, an analytical model to predict the initial weld line placement necessary to satisfy the desired, final weld line location is presented. Good agreement between the model, experimental results, and numerical simulations with respect to weld line movement and initial placement was obtained for a symmetric, steel TWB case and a non-symmetric, Aluminum TWB case.

Maximum Bulge Height and Weld Line Displacement in Hydroforming of Tailor Welded Blanks

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
A. Kumar ◽  
V. Gautam ◽  
D. R. Kumar
Keyword(s):  
Weld Line ◽  
Thickness Ratio ◽  
Dome Height ◽  
Interstitial Free ◽  
Tailor Welded Blanks ◽  
Tailor Welded Blank ◽  
Hydraulic Bulging ◽  
Weld Line Movement ◽  
Bulge Height ◽  
Line Movement

Tailor welded blank (TWB) has many advantages over a traditional blank for manufacturing automobile sheet metal components, such as significant flexibility in product design, higher structural stiffness, and crash behavior. However, lower formability and weld line movement are some of the problems associated with forming of TWBs. Hydroforming is a potential technique to enhance formability. In this work, the effect of thickness ratio on maximum dome height and weld line movement in hydraulic bulging of laser welded interstitial-free (IF) steel blanks of different thickness combinations has been predicted using finite element (FE) simulations. The results are also validated with hydraulic bulging experiments on TWBs. It has been found that with increase in thickness ratio, the maximum bulge height decreased and weld line displacement toward thicker side increased. These results have been used to relocate the weld line toward the thinner side in the initial blanks and achieve a more uniform bulge profile of the dome. The peak pressure to achieve maximum safe dome height and percentage thinning has also been found out. The results showed huge improvement in uniformity of bulge profile with little reduction in dome height.

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