Segmented Blank Holder Research Articles

Individually segmented blank holding system driven by electromagnetics for stamping: Modeling, validation, and prototype

Previous efforts have shown that the segmented blank holder consisting of several controlled parts, can effectively improve forming quality and reduce defects in stamping. However, low response and high complexity will occur when using the conventional hydraulic drive for forming. In this paper, a novel electromagnetic system to drive the individually segmented blank holder was proposed. The mechanism of the electromagnetic force generated by the electromagnetic drive was first theoretically modeled, where the three-dimensional equivalent magnetic circuit was established and the B-H curve was embedded to precisely solve the electromagnetic force. Under the action of the electromagnetic force, the transmission mechanism through a force transmission structure was revealed to quantify the holding force. The accuracy of the modeling was validated by simulations, and the comparisons between the model and the simulation indicate that the error is in the range of [2 %, 7 %]. The electromagnetic drive with the individually segmented blank holder for the downscaling part of the car door was then configured based on the developed design flow. The experimental bench was built to test the generation and transmission of electromagnetic force. The prototype of the electromagnetic individually segmented blank holding system was developed for forming without defects. Results show that the electromagnetic force transmission mechanism designed based on the modeling can meet the requirements of the blank holding, the electro-permanent magnet with segment blank holder is feasible, and the models have certain accuracy and reliability. This work assisted in configuring the individually segmented blank holder achieved by electromagnetics to meet the high-quality forming demands.

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

深絞り加工における板厚変動最小化を目的とした分割可変ブランクホルダー力の最適軌道設計

深絞り加工における板厚変動最小化を目的とした分割可変ブランクホルダー力の最適軌道設計

Optimization of Segmented Blank Holder Shape and Its Variable Blank Holder Gap in Deep-Drawing Process

Optimization of Segmented Blank Holder Shape and Its Variable Blank Holder Gap in Deep-Drawing Process

J122011 Optimization of Segmented Blank Holder Shape and Its Variable Blank Holder Gap in Deep-Drawing Process

J122011 Optimization of Segmented Blank Holder Shape and Its Variable Blank Holder Gap in Deep-Drawing Process

Influence of Segmented Blank Holder for Rectangular Box Drawing

Blanker holder force (BHF) is one of the important parameters in sheet metal forming process, which is loaded by blanker holder in order to avoid wrinkling. With the development of technology, segmented blanker holder is applied to complicated product forming in order to improve the parts quality. On the basis of analyzing the character of rectangle box forming, the blank holder was divided eight portions, including 2 long straight segments, 2 short straight segments and 4 corners, which each part can separately move. Then the forming simulation of the low carbon steel rectangular box with segmented constant BHF was conducted using orthogonal experiment and considering test conditions. After the results were analyzed according to the thinnest level of the parts, the influence of the segmented blank holder on rectangular box forming was obtained. It indicates that the segmented blank holder has the ability of the local control to sheet metal forming, and can effectively adjust material flow and the strain distribution.

Study on Segmented Variable Blank Holder Force Method of Rectangular Box Drawing

The form of blank holder and the manner of blank holder force (BHF) on the complicated parts forming are very important. The blank holder of rectangle box forming was divided long straight segments, short straight segments and corners. The forming process simulation of rectangular box was conducted by FEM based on explicit algorithm, including single-piece blank holder with constant BHF, single-piece blank holder with variable BHF, segmented blank holder with constant BHF, segmented blank holder with variable BHF. The results were analyzed according to the thinnest level of the parts. The displacement in the Z direction of blank holder in the simulation was considered, and the method of determining segmented variable blank holder force (VBHF) was proposed. Finally rectangular box was obtained by rectangular box drawing system of segmented variable BHF on the basis of the simulation result.

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

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.

Study for Rectangular Box Drawing of Segmented Variable Blank Holder Force

The sheet forming simulation of rectangular box was conducted by finite element method (FEM), the forming process experiment, further, was investigated, so as to understand the effect of the form of blank holder and the manner of blank holder force (BHF) on the complicated parts forming. In my study, a kind of low carbon steel was investigated, and its mechanical properties were obtained by simple tension tests. The outermost contour of the blank shape was determined by “one step method”. Furthermore, the finite element model was constructed by ANSYS parametric design language (APDL), which has characteristic of grid meshing by Belytschko-Tsay (BT) shell element, applying anisotropic constitutive equation of Barlat yield criterion, dealing contact by penalty function method and using adaptive mesh algorithm in the simulation process. Then the forming process simulation of rectangular box with segmented variable BHF was conducted. On the basis of analyzing the work principle and technical parameters of XP3CEF-100 hydraulic press, the rectangular box drawing system of segmented VBHF was established, which was made of hydraulic press, rectangular box drawing die of segmented blank holder, hydraulic part of blank holder and control part. Finally the low carbon steel forming tests were fulfilled by the rectangular box drawing system on the basis of the simulation result.

Deep drawing of aluminium–steel tailor-welded blanks

Aluminium and steel blank sheets can be welded together to produce tailor-welded blanks with strength mismatch. These tailor-welded blanks are applied in aerospace and automotive industries. In this investigation, finite element simulations were carried out using home code DD3IMP to determine the formability characteristics of aluminium–steel tailor-welded blanks. Aluminium (AA6016-T4) blank sheet was combined with a range of steel blank sheets namely, mild-steel (DC06) and high strength steels (AISI-1018, HSLA-340, and DP600) to form four different Al–steel tailor-welded models. Aluminium, being relatively weaker, has the tendency to flow more than steel. In particular, dual-phase steel offers the maximum resistance to flow and mild-steel offers lowest resistance. A segmented blank holder allows the application of different forces on aluminium and steel sheet segments in the tailor-welded blank. Different blank holder forces enhance the formability of tailor-welded blank as well as control the draw-in. The simulation results indicate that even with large dissimilarities in material properties, Al–steel tailor-welded blanks can produce superior deep drawn parts.

Hydromechanical Deep Drawing of Tailor Welded Blanks

This paper investigates the conventional and hydromechanical deep drawing of circular tailor welded blanks (TWBs) with a linear weld line. TWBs offer the possibility to combine different materials, different thicknesses and different coatings within one part, as to optimally fit the applied loads with the lowest possible weight. By combining the hydromechanical deep drawing process with TWBs, a new range of applications can be offered. For the investigations experimental trials are carried out, as well as finite-element simulations. The material parameters of the parent materials and of the weld line are determined and included in the modelling of the TWB. A tool die is designed allowing the hydromechanical deep drawing of TWBs while taking into account the sealing of the TWB and the gap in thickness created by blanks of different thickness. In this way a different blank holder pressure can be applied on each side of the TWB, using a segmented blank holder and a multi-point cushion system. The goal of this study is to investigate the influence of the counter pressure on the deep drawing process of TWBs with particular interest given to the weld line movement during the forming process. It is found that the deep drawing process can be simulated accurately by the finite-element analysis and that the weld line movement plays a crucial role in the deep drawing of a sound part.