Blank Development Research Articles

Modelling of Neutral Line Parameter for Sheet Metal Stamping and Roll Forming Processes

The blank development of sheet metal for the stamping and the roll forming processes is crucial for the dimensional accuracy of the products. The neutral line parameter is the indicator to present the thinning phenomenon at the bending corners of the products. The basic assumption of the neutral line position is the surface that the sheet metal remains un-deformed after the stamping or the roll forming process. The conventional determination method of the neutral line position is based on the zero strain position through the thickness direction of the blank. In this paper, a different neutral line factor calculation method based on the mean profile length was proposed to find the neutral line factor, which is directly related to the profile length and more precise for the bland development calculation. A cross sectional profile was obtained after the forming process and the mean profile length of the upper and the lower surface was obtained. The ratios of the bending radius to the sheet thickness were calculated using the FEM simulation. A neutral line equation was proposed considering the material mechanical properties and the bending tool parameters. The initial blank width was compared to the forming result of the CAE simulation to validate the neutral line model. This model is able to take into consideration of the thinning effect at the entire bending zone of the metal forming without the assumption of the uniform thinning and is more accuracy for the blank width calculation.

Development of a STEP-compliant design and manufacturing framework for discrete sheet metal bend parts

Metal sheets have the ability to be formed into nonstandard sizes and sections. Displacement-controlled computer numerical control press brakes are used for three-dimensional sheet metal forming. Although the subject of vendor neutral computer-aided technologies (computer-aided design, computer-aided process planning and computer-aided manufacturing) is widely researched for machined parts, research in the field of sheet metal parts is very sparse. Blank development from three-dimensional computer-aided design model depends on the bending tools geometry and metal sheet properties. Furthermore, generation and propagation of bending errors depend on individual bend sequences. Bend sequence planning is carried out to minimize bending errors, keeping in view the available tooling geometry and the sheet material properties’ variation. Research reported in this article attempts to develop a STEP-compliant, vendor neutral design and manufacturing framework for discrete sheet metal bend parts to provide a capability of bidirectional communication between design and manufacturing cycles. Proposed framework will facilitate the use of design information downstream at the manufacturing stage in the form of bending workplan, bending workingsteps and a feedback mechanism to the upstage product designer. In order to realize this vendor neutral framework, STEP (ISO 10303), AP203, AP207, and AP219 along with STEP-NC (ISO14649) have been used to provide a basis of vendor neutral data modeling.

Cold Roll Forming Process and Die Design for Double-Gutter Frame of Drawer Slider

In this paper, the main focus is to demonstrate a systematic method of designing the roll flower and corresponding dies for a double-gutter frame applied to the drawer slider. The blank development method was proposed to calculate the width of blank for bending with small radii. The cold roll forming process design was based on the maximum longitudinal strain minimization and the interference of rolls with the double-gutter geometry of product profile. Extra pre-bending was designed to avoid the occurrence of blank collision during forming process. The FEM method was adopted to evaluate the process and die designs. Due to the geometry complexity of the product, strain distribution is uneven which results in more spring back and stress concentration. A geometry setting design was proposed to create local strain redistribution and smooth strain distribution of entire section profile after final forming step. Using geometry setting die design, the spring back at the end point and the gutter areas of final product section are 0.07 mm and 0.1 mm, respectively. Without the geometry setting die design, the spring back at the end point and the gutter areas of final product section are 0.11 mm and 0.15 mm, respectively. The simulation results demonstrate the proposed methods are able to improve the accuracy of cold roll forming products.

A comprehensive blank development method for forming sheet metal parts

For some shortcomings in the use of standard radial length development in the blank development for forming sheet metal parts, an improved radial length normal spreading approach considering outside normal direction is developed to resolve blank development in sheet metal forming. Moreover, a comprehensive spreading method, which combines radial length normal spreading and orthogonal length development method, is presented in this paper to avoid the overlapping problem which happens sometime in the spreading process related to severely curved sheet parts. To deal with holes and gaps which exist in some sheet metal parts, dummy elements are used to calculate the intercepting line’s length precisely. Finally, a multistep spreading and merging strategy is adopted to handle some special sheet metal parts with vertical free edges that should be jointed or not. Through practical applications, the effectiveness and the usefulness of this approach are evaluated, and the unfolded result is more reasonable; meanwhile, the obtained blank shape should be a better initial guess in the application of the so-called one-step quick analysis for sheet metal forming simulation.

Applications of advanced metrology techniques for the characterization of extreme ultraviolet mask blank defects

Characterization of defects and their sources is essential for developing mitigation solutions to support the production of defect-free extreme ultraviolet (EUV) mask blanks. The characterization of sub-100-nm defects pose challenges to the conventional metrology techniques, such as atomic force microscopy and scanning electron microscopy, limiting mitigation of nanoscale defects. SEMATECH’s Mask Blank Development Center houses advanced metrology capabilities that include transmission electron microscopy (TEM) and Auger electron spectroscopy (AES) to address these shortcomings. Scanning TEM was used to study the disruption of the Mo/Si multilayer of phase defects and to perform elemental analysis with energy dispersive x-ray spectroscopy that has supported projects including substrate smoothing activities, deposition simulation development, and defect printability studies. The Auger instrument was used to create elemental maps for defect identification and to characterize the ion beam deposition tool. Using advanced metrology, mitigation of small defects is being realized, yielding mask blanks with defect counts as low as eight defects at 50-nm sensitivity (Lasertec M7360 SiO 2 sphere equivalent) measured over the quality area of 132×132 mm 2 . The issues with the metrology of increasingly small EUV mask blank defects will be outlined, and comprehensive defect characterization results using TEM and AES will be presented.

An efficient spreading method for sheet metal parts based on outside normal

PurposeThe paper's purpose is to provide a new spreading method for sheet metal parts, which aims to improve the standard radial spreading method.Design/methodology/approachA new radial spreading approach considering outside normal direction, which is based on geometric mapping method and triangle elements, is developed to resolve blank development in sheet metal forming.FindingsThrough practical applications, the effectiveness and usefulness of the approach presented are evaluated, and the development result is more reasonable, meanwhile, the obtained blank shape should be a better initial values in the application of one‐step analysis for fast deep drawing simulation.Originality/valueThis paper offers a more reasonable spreading method for sheet metal parts.

Layer-by-layer-reverse-planishing blank estimation approach and its implementation

Based on the hole-expanding forming theory in plastic mechanics, applying the layered idea, a layer-by-layer- reverse-planishing blank shape estimation approach is proposed for the complex cover panels with free form surface so that the blank shape estimation can be executed effectively. The present approach considers synthetically the influence of material mec- hanical properties, work-hardening effect and plastic defor- mation during cover panels forming on blank shape. Simult- aneously, the base-surface idea of the section curve length dev- elopment approach is adopted in order to determine the initial blank contour shape and position. Furthermore, by applying the continuity between adjacent layers during surface development- planish, this estimation approach develops a surface layer by layer according to the order of layering-planishing-expanding- re-layering. Therefore, it is expected to reduce effectively the amount of calculation and improve blank development effic- iency. Finally, by comparing the blank area, material utilization ratio, and stamping test results of the example’s development result with ones of the given traditional blank shape, the validity and reasonability of the proposed blank estimation approach are verified.

Progress in the fabrication of low-defect density mask blanks for extreme ultraviolet lithography

Extreme ultraviolet lithography (EUVL) is the leading next-generation lithography (NGL) technology to succeed optical lithography at the 32-nm node and beyond. The technology uses a multilayer-based reflective optical system, and the development of suitable, defect-free mask blanks is the greatest challenge facing the commercialization of EUVL. We describe recent progress toward the development of a commercial tool and process for the production of EUVL mask blanks. Using the resources at Mask Blank Development Center at SEMATECH-North in Albany, New York, we are able to decrease the mean multilayer-coating-added defect density on 6-in. square quartz substrates by almost an order of magnitude, from ~0.5 defects/cm2 to ~0.055 defects/cm2 for particles 80 nm in size (polystyrene latex equivalent). We also obtain a "champion" mask blank with an added defect density of only ~0.005 defects/cm2. This advance is due primarily to a compositional analysis of the particles using focused ion beam and energy dispersive analysis of x-rays (EDX) followed by tool and procedural upgrades based on best engineering practices and judgment. Another important specification for masks blanks is the coating uniformity, and we have simultaneously achieved a centroid wavelength uniformity of 0.4% and a coating-added defect density of 0.06 def/cm2.

NEW ENHANCEMENTS IN THE INVERSE APPROACH FOR THE FAST MODELING OF AUTOBODY STAMPING PROCESS

International Journal of Computational Engineering ScienceVol. 03, No. 04, pp. 355-384 (2002) No AccessNEW ENHANCEMENTS IN THE INVERSE APPROACH FOR THE FAST MODELING OF AUTOBODY STAMPING PROCESSH. NACEUR, Y. Q. GUO and W. GATIH. NACEURLab. Roberval, University of Technology of Compigne, UMR 6066 du CNRS, BP 20529 - 60205, Compigne Cedex, FranceCorresponding author. Search for more papers by this author , Y. Q. GUOLab. of Mechanics, Materials & Structures (GMMS), University of Reims, U.F.R. Sciences E.N., Moulin de la Housse, BP 1039-51687 Reims, France Search for more papers by this author and W. GATILab. Roberval, University of Technology of Compigne, UMR 6066 du CNRS, BP 20529 - 60205, Compigne Cedex, France Search for more papers by this author https://doi.org/10.1142/S146587630200068XCited by:10 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractWith the development of finite element method and computer technology, the complete modeling of the forming of a 3D sheet metal part using incremental approaches is becoming realistic. However, an accurate 3D simulation is usually too time-consuming to be used in the early design stage. One solution is to use simplified Inverse or One Step approaches for the sheet forming modeling. Unfortunately, these methods often based on implicit static algorithms, suffer from convergence problems because of strong non-linearities. In this paper we firstly present several initial guess methods to speed up the convergence of the implicit static solver used in the Inverse Approach, then we present some new techniques for the treatment of vertical walls (balancing, opening, matrix condensing,) which has proven to be essential when dealing with complicated parts. All these improvements have been introduced into our in-house F.E. software REFORM and applied to the drawing of industrial automobile parts. The obtained rapid convergence enables the easy determination of various process parameters for the design of sheet forming process. It is concluded that a good initial solution and the treatment of vertical walls play an important role to speed up the Inverse Approach modeling of autobody stamping processes.Keywords:Deep DrawingInverse Approachinitial solutiongeometric mappingnon-linear resolution FiguresReferencesRelatedDetailsCited By 10Modeling and Optimization in Manufacturing by Hydroforming and StampingHakim Naceur and Waseem Arif27 April 2021Damage Prediction in Metal Forming Process Modeling and Optimization: Simplified ApproachesYing-Qiao Guo, Yuming Li, Boussad Abbès, Hakim Naceur and Ali Halouani4 September 2014A comprehensive blank development method for forming sheet metal partsJianjun Wu, Xin Wu, Liangcai Deng and Hakim Naceur13 December 2013 | The International Journal of Advanced Manufacturing Technology, Vol. 71, No. 5-8An initial solution estimation method based on As‐Rigid‐As‐Possible mesh parameterization for one‐step simulationQiaosheng Liu, Juntong Xi and Zhuoqi Wu29 Mar 2013 | Engineering Computations, Vol. 30, No. 3Damage Prediction in Metal Forming Process Modeling and Optimization: Simplified ApproachesYing-Qiao Guo, Yuming Li, Boussad Abbès, Hakim Naceur and Ali Halouani15 May 2014Analysis and design of hydroformed thin-walled tubes using enhanced one-step methodXavier Elie-dit-cosaque, Mohamed Said Chebbah, Hakim Naceur and Augustin Gakwaya2 August 2011 | The International Journal of Advanced Manufacturing Technology, Vol. 59, No. 5-8A membrane element model with bending modification for one step inverse methodJingxin Na, Jian Jiao, Yakun Yan and Haipeng Liu1 Jun 2011 | Acta Mechanica Solida Sinica, Vol. 24, No. 3An efficient spreading method for sheet metal parts based on outside normalWu Jian‐jun and Yang Han‐ping18 Jul 2008 | Engineering Computations, Vol. 25, No. 5Approche inverse améliorée pour la minimisation du retour élastique de pièces emboutiesSlim Ben-Elechi, Hakim Naceur, Catherine Knopf-Lenoir and Jean-Louis Batoz15 May 2012 | European Journal of Computational Mechanics, Vol. 17, No. 3Moving least squares response surface approximation: Formulation and metal forming applicationsPiotr Breitkopf, Hakim Naceur, Alain Rassineux and Pierre Villon1 Jun 2005 | Computers & Structures, Vol. 83, No. 17-18 Recommended Vol. 03, No. 04 Metrics History KeywordsDeep DrawingInverse Approachinitial solutiongeometric mappingnon-linear resolutionPDF download

5561754 Area preserving transformation system for press forming blank development : Oliver James H; Nair Nirmal K Ames, IA, United States assigned to Iowa State University Research Foundation Inc

5561754 Area preserving transformation system for press forming blank development : Oliver James H; Nair Nirmal K Ames, IA, United States assigned to Iowa State University Research Foundation Inc

Blank development and the prediction of earing in cup drawing

The article deals with the prediction of blank shapes using the method of plane strain characteristics. In one case the material is assumed to be an incompressible, non-hardening, isotropic solid, and ideal blank shapes are developed when deep drawing prismatic cups. The significance of the study is that the resulting slip line field pattern does not violate the Hencky equations. The earing behaviour when deep drawing cylindrical cups from circular disks has also been predicted based on a particular form of anisotropy which allows for four fold symmetrical earing. The technique permits the blank shape to be calculated throughout the entire drawing operation, and demonstrates how the ears develop.

Determination of the Optimum Blank Shape When Deep Drawing Nonaxisymmetric Cups, Using a Finite-Element Method : Simplified Determination of Optimum Blank Shape and Limiting Drawing Ratio by Inverse Finite-Element Procedure

The article is concerned with blank development when deep drawing nonaxisymmetric, prismatic cups with a flat bottomed punch. Two processes are considered, one of which is the calculation of optimum blank shapes when deep drawing square cups ; here optimum means that the cups have essentially a flat top after the drawing process. The second process is to design a blank such that the finished component is a partially drawn cylindrical cup possessing a square flange of some specified dimensions. An inverse finite-element technique was developed to perform the analysis for calculating the blank shapes. In addition to blank shapes, it was possible to predict the limiting drawing ratios, the maximum draw depth and the drawing load. Although the entire drawing process is not modeled, it is possible to assess the influence of certain processing parameters such as blank shape, the coefficient of friction, blank holder force, and die radius on the drawing force and limiting drawing ratio. Some of the theoretical predictions for the limiting blank size in deep drawing square cups from optimum-shaped blanks are compared with published data, and the agreement is found to be reasonable.

Blank Development and Tooling Design for Drawn Parts Using a Modified Slip Line Field Based Approach

Box shaped parts demonstrate unusual characteristics as opposed to the drawn cylindrical cups. A novel approach for blank development, based on the modified plane strain slip line field (SLF), is presented in this work. The approach is to balance the element volume between the final position in the wall and the starting position in the flat flange. The end result of this SLF based unfolding technique is a set of elements representing the deformation path of the part. By post-processing the information on the nodal coordinates and invoking the variational principle in its incremental form, the strain distribution in the flange and the wall stresses are determined. A methodology is also presented for understanding the implications of the metal flow lines for tooling design.

Modelling of flange deformation of irregular drawn cups using a fluid analogy

An analogy is shown to exist between the flow of a viscous fluid and the plane strain deformation of the flange of a deep-drawn cup. A method of finding optimum blank shapes based on the outward extrusion of a viscous fluid between parallel plates is demonstrated. Using this analogy, a computer simulation method is introduced and optimum blank contours obtained for drawing cups of uniform height for a wide variety of cross-sectional shapes. It is suggested that this approach leads to a useful, rapid and accurate computer-aided design method for blank development of irregular deep-drawn cups.

Ego development and psychopathology.

The relationship between ego development and psychopathology was studied, using Loevinger's Washington University Sentence Completion Blank and ego development rating method. The levels of ego development of the population at a private psychiatric clinic were found to be significantly lower than those of Loevinger's manual construction and revision sample. Using the MMPI as a classification guide, individuals at the lower levels of ego development were found to be primarily diagnosed as character-logical. The relationship between ego development and IQ on the WAIS was also noted. The present study adds credence to the usefulness of Loevinger's Washington University Sentence Completion Test for Ego Development as a clinical instrument.