Rectangular Cup Research Articles

Development of a novel forming tool for the production of high-strength aluminum components with tailored properties

Because of growing environmental and technical requirements, the efficient manufacturing of components with tailored properties using recyclable materials is mandatory. The combination of high-strength aluminum alloys and thermal-assisted forming operations is an innovative method for the production of components with varying mechanical properties. By locally adjusting the cooling rates during a thermo-mechanical forming operation, it is possible to modify the microstructure and precipitation conditions. A subsequent aging operation causes different microstructural and mechanical characteristics. This allows both deep-drawing and adjustment of the component properties in one single step. For this reason, this contribution focuses on the production of components with tailored properties. With the aid of a non-contact measuring system, previous investigations have proved that mechanical material properties can be adapted during a forming process by adjusting the cooling rates. In this contribution, this knowledge is transferred to a novel temperature-controlled rectangular cup tool. A variation of the local tool temperature and holding duration in the tool will be carried out. Then, the mechanical and microstructural properties of the manufactured components will be characterized through hardness and DSC investigations. In addition, the influence of different tool temperatures on the component temperature, the sheet thickness distribution and process forces will be investigated. As a result, it has been demonstrated that mechanical, process-related and geometric advantages can be achieved by using locally temperature-controlled forming tools.

The Effect of Die Geometry on Cup Damages in Cold Deep Drawing of Rectangular Cups

Derin çekme, zımba kuvveti uygulanarak sac malzemenin kalıp boşluğuna akışıdır. Derin çekmede, düz ince tabakalar arasında sacı istenen şekle getirmek için zımba kullanılarak sacı merkez kısmından kalıp boşluğuna iterek kaplar üretilmektedir. Derin çekilmiş kaplarda kabın köşe yarıçaplarında boyun oluşumu veya çatlamaların oluşması nedeniyle daha yüksek çekme oranları elde edilememektedir. Bunun için derin çekme işleminin başarılı olmasında uygun işlem parametrelerinin doğru seçilmesi önemlidir. Bu makalede, dikdörtgen geometriye sahip kapların derin çekilmesinde matris üst yüzeyine ve pot çemberinin alt yüzeyine açılar verilerek matris geometrisinin, kap kesit incelmeleri ve hasarları üzerinde olan etkileri tespit edilmiştir. Bunun için matris üst yüzeyine/pot çemberi alt yüzeyine 0°, 3°, 6° ve 9°’lik açılar verilmiştir. Pot çemberi kuvveti sabit 1800 daN ve stampa hızı da sabit 4 mm/s olarak uygulanmıştır. Derin çekme işlemlerinde, matris/stampa arası boşluk 1.2 mm, stampa uç ve kenar radyüsleri ile matris ağız yarıçapları 6 mm alınmıştır. Çalışmada kalınlığı 1 mm olan St37 çeliği kullanılmıştır. Cidar kalınlıkları Mitutoyo LH-600E hassas lineer ölçüm cihazında 0.001 hassasiyetinde nokta temaslı olarak ölçülmüştür. Kap yükseklikleri artıkça kaplardaki cidar incelmelerinin arttığı, maksimum incelmenin kabın alt kısımlarındaki köşelerde meydana geldiği ve bu değerin 0,373 mm olduğu tespit edilmiştir. Plastik deformasyonun en çok etkilediği bölge kap alt bölgesidir. Bu bölgede deformasyon sertleşmesi nedeniyle maksimum basma ve çekme kuvvetleri oluşmakta ve dolayısıyla maksimum gerilme ve sertlik bu kısımda meydana gelmiştir. Maksimum sertlik kabın tabanının olduğu bölgede ve 61.4 HRC olarak ölçülmüştür. Minimum sertlik kap üst bölgesinde ölçülmüştür. Kabın üst ağız kısımlarına doğru sertliğin daha da düştüğü ve 43.8 HRC olduğu görülmüştür. Ortalama sertlik değeri ise 53.1 HRC olarak tespit edilmiştir. Sonuç olarak, dikdörtgen geometriye sahip kapların soğuk derin çekilmesinde, matris üst yüzeyine ve pot çemberinin alt yüzeyine açılar verilerek kalıp geometrisinin, kap cidar kalınlık değişimleri ve kap hasarları üzerinde önemli bir etkisinin olduğu tespit edilmiştir.

Wrinkling limit curves with consideration of anisotropic behaviour for the deep drawing of aluminium sheet alloys

In this work, a combined experimental and finite-element (FE)-based approach was introduced for determining the wrinkling limit curves (WLCs) of sheet metals during forming processes. Aluminium sheets of grade AA5052-O and AA5052-H32 with different formabilities and anisotropic behaviours were investigated. Modified Yoshida buckling tests were carried out for aluminium sheets in both the rolling (RD) and transverse direction (TD). In parallel, FE simulations of the buckling tests were conducted, in which the Hill’48 (both r- and stress-based) yield criteria and Swift strain hardening law were incorporated. Local principal strain histories of observed wrinkle areas on both surfaces of samples were gathered from the simulations and the state of wrinkling initiation was then identified at the inclination of these strain paths. The calculated strain values were verified with developed compressive stresses as well as corresponding strains measured by a digital image correlation technique. The influences of material anisotropies and used yield functions on the determined WLCs were discussed. Subsequently, the determined WLCs were applied for evaluating non-flange wrinkling formation during a rectangular cup drawing test. The forming tests were experimentally and numerically performed for the examined aluminium sheets in both RD and TD. It was found that strain distributions of critical side wall areas at predicted wrinkling onset and severe wrinkle states were well correlated with the WLCs. Thus, WLCs based on the r-based criterion could more accurately describe the non-flange wrinkling incidents of the cup-drawn samples than those of the stress-based model.

Optimization of process parameters for rectangular cup deep drawing by the Taguchi method and genetic algorithm

Abstract This article presents the optimization of process parameters in reducing the risk of failure due to wrinkling and fracture in deep drawing of a rectangular cup. Blank holder force, friction coefficient, punch radius and initial blank shape were chosen as design parameters. Wrinkling and fracture criteria were used as objective functions. Two-stage optimization approach was used. In the first stage optimization, optimum blank shape was determined using the Taguchi optimization method. In the second stage optimization, optimum parameter values were determined for the selected blank shape by the first stage optimization using genetic algorithm. In the second stage of optimization, response surface models based on 3-level full factorial design of experiments were constructed. Finite element simulation results were used for creating response surface models. Parameters obtained from optimization study were confirmed by conducting deep drawing simulations using commercial code DYNAFORM 5.9.2. Optimum results showed that proposed optimization methodology can solve wrinkling and fracture problems in the sheet metal forming process.

Deep drawing of a rectangular cup with a small radius at the bottom circular arc by employing a locally-thickened plate

A rectangular cup with a small radius at the bottom circular arc is a common sheet metal structure in aerospace components. However, when aluminum alloy plates are used for deep drawing of this type of rectangular cups, the wall thickness around the bottom circular arc is severely decreased. Hence, in this paper, locally-thickened plates were adopted for deep drawing of aluminum alloy rectangular cups with a relatively small radius at the bottom circular arc. The effect of thickening parameters of a locally-thickened plate on the radius at the bottom circular arc and the forming load was investigated by employing finite element simulations and deep drawing experiments. The results indicate that a smaller radius at the bottom circular arc is obtained by increasing the angle or reducing the thickness of the thickened convex rib of a plate. Moreover, the aforementioned is achieved when the side length of the thickened convex rib is equal to the punch width. The forming load is closely related to the thickening parameters of a locally-thickened plate. A small radius of 5 mm at the bottom circular arc was successfully obtained by optimizing the thickening parameters. Furthermore, the forming load during the deep drawing was significantly reduced.

Açılı Derin Çekme Kalıplarında Dikdörtgen Şekilli Kapların Derin Çekilebilirliğinin Araştırılması

Deep drawing is the process of obtaining three-dimensional containers of certain depths and shapes under pressing forces with the help of drawing molds of sheet materials. In this study, the numerical shaping of rectangular cups in angled deep drawing dies was investigated experimentally and by using the finite element method (FEM). For this purpose, die/blank holder surfaces have α=0°, α=3°, α=6°, α=9°, α=12° and α=15° angles in order to facilitate material flow into the die cavity. The punch and die corner radii are taken as 8 mm. St37 steel sheet with a thickness of 0,9 mm was used as the test material. The experiments were carried out by applying die/blank holder forces of 2500 N, 5000 N, 7500 N and 10000 N. The effects of angles and die/blank holder force on limit draw ratio, wall thickness and the damage of cups were investigated experimentally and numerically, and optimum punch force was determined. Obtained experimental results were compared with ANSYS results. As a result, it has been determined that the increase in die/blank holder surface angles in drawing dies with rectangular geometry with different angles provides a higher limit drawing rate than conventional dies. It has been seen that the experimental results and numerical results are approximate values.

Analysis of rectangular cup drawing considering anisotropic hardening and cyclic effect for orthogonal anisotropic materials

An anisotropic plasticity model is developed based on the non-associated flow rule with anisotropic hardening. The model combines non-quadratic yield function and quadratic plastic potential function for orthogonal anisotropic sheet metals. The model is also expanded to properly reproduce the cyclic effect during forming processes. The simple formulations can contribute to cost saving in the parameter acquisition process and implementation. The developed model was implemented into the finite element code ABAQUS as a user material subroutine under a general three-dimensional condition. To evaluate the capability of the plasticity model, different loading conditions and prediction of the yield surface were considered. A multi-step rectangular cup drawing process with the AA5182-O and DP600 sheets including draw/re-draw effects was applied to evaluate the performance of capturing complex plastic behavior by finite element simulation. The results show that the anisotropic plasticity model is capable of describing the anisotropic behaviors including anisotropic hardening and cyclic hardening with high accuracy and efficiency.

Modeling plastic anisotropy evolution of AISI 304 steel sheets by a polynomial yield function

In this study, a numerical model for the evolution of plastic anisotropy is investigated for the purpose of stamping method design by Finite Element (FE) analysis and proved experimentally via process simulations of a cold-rolled austenitic stainless steel (AISI 304) sheet. The plastic anisotropy of the sheets is described with a fourth-order homogenous polynomial yield function and this modelling approach is enhanced by plastic strain dependent material coefficients. Tensile tests of coupon specimens taken along the different directions from rolling direction, and flow strength and deformation anisotropies are described with the planar variations of yield stress and plastic strain ratio computed at four plastic strain levels (0.002, 0.02, 0.05 and 0.18). A new numerical approach is, then, applied to identify polynomial coefficients ensuring an orthotropic positive-definite, convex yield surface with a well-defined stress gradient at every loading point on plane stress subspace. The developed computational model is implemented into general purpose explicit FE analysis software Ls-Dyna by a user-defined material model subroutine (UMAT) and applied in the stamping simulation of AISI 304 steel rectangular cups for the house-hold applications. The computed thickness distributions and the flange geometries were compared with measurements and it was observed that the best predictions were done with material parameters at %5 plastic strain level.

Development a new methodology for measuring deep drawing forces based on dimensionless evaluation

In this research work, dimensionless models based on geometric parameters have been developed for the deep drawing process of rectangular cups to reduce the manufacturing costs on a large scale of application in a noticeable way. In the following, geometric parameters were given in dimensionless form by the Π-Buckingham dimensional analysis method and a series of dimensionless groups were found for both circular and rectangular initial blank. To find the best group of dimensionless geometric parameters, different cup scales 1:1, 2:1, 4:1 and 5:1 are evaluated numerically by ABAQUS Finite Element (FE) software, validated by experimental work. After all effective geometric parameters have been analyzed, the best fitting relational model of dimensionless parameters is found for rectangular and circular blank separately. Various thicknesses of St12 sheet metals were used for experimental validation, which were formed at room temperature. Also, results and response parameters were compared in the simulation process, experimental tests and dimensionless models. By looking at the outcomes, it is demonstrated that the geometric qualities of a large scale can be predicted by a small scale, utilizing the proposed dimensionless model. A comparison of the outcomes for dimensionless models and experimental tests shows that proposed dimensionless models have a high degree of precision in determining geometrical parameters and the prediction of drawing force. Furthermore, the dimensionless analysis was generalized to ensure high precision estimation of geometric values for large geometric scales.

Tearing defect maps for the deep drawing of AISI 304 rectangular cups

Abstract This study proposes a method for integrating finite element analysis and response surface methodology to predict tearing locations in the deep drawing of a rectangular-shape AISI 304 cup. The finite element model was confirmed by a deep-drawing experiment with nitrogengas springs, and the finite element analysis results were in agreement. Moreover, the regression model was developed using response surface methodology to predict final thickness at various locations on the rectangular-shape deep-drawn cup based on 40 finite element cases containing varied blank holder forces. The maximum percentage of thinning values was obtained from the response surface methodology results. The relationships among the blank holder forces and the thinning values at different locations were then further developed. The maps of the predicted tearing locations were then obtained and directly corresponded to the number of locations the specific blank holder forces. These maps, as established, could be directly used in a closed-loop control system enabling tearing defects to be prevented or eliminated.

Wrinkling Prediction of Rectangular Cup Deep Drawing Process for Aluminum Alloy Sheets by Using the Modified Yoshida Buckling Test

Nowadays, the industry has been growing interest in lightweight material for automotive and cookware manufacturing. The formability of sheet material is an important issue in these industries. The wrinkling behavior is one of the most failure in sheet metal forming and is often occurred in deep drawing process in cookware manufacturing. In this work, the developed wrinkling limit curves (WLCs) using experimental and numerical simulation of a modified Yoshida buckling test were precisely used to predict the wrinkling behavior of rectangular cup deep drawing for aluminum alloy sheets grade AA5054-O and AA5052-H32. The Industrial parts, the rectangular cup deep drawing was firstly performed for both investigated aluminum sheets for obtaining the wrinkling initiation on the side wall area of deep drawing parts. Subsequently, the experimental formed parts were carefully measured the draw-in of deformed blank sheets and drawing depth to validate the finite element (FE) model. Then, the FE simulation of the corresponding drawing tests were calculated, by which were implemented with the Hill’48 yield criterion and Swift hardening law to descript anisotropic plastic deformation. As a result, the local principle Major and Minor principle strains of observed wrinkle areas were gathered in the side wall area of the rectangular cup deep drawing test. Finally, the developed WLCs of aluminum alloy sheets were applied to predict the wrinkling formation of the formed deep drawing parts. Comparatively, the influence of different aluminum alloy grades on the WLCs and wrinkling behavior were explicitly investigated.

Tearing defect maps for the deep drawing of AISI 304 rectangular cups

Abstract This study proposes a method for integrating finite element analysis and response surface methodology to predict tearing locations in the deep drawing of a rectangular-shape AISI 304 cup. The finite element model was confirmed by a deep-drawing experiment with nitrogengas springs, and the finite element analysis results were in agreement. Moreover, the regression model was developed using response surface methodology to predict final thickness at various locations on the rectangular-shape deep-drawn cup based on 40 finite element cases containing varied blank holder forces. The maximum percentage of thinning values was obtained from the response surface methodology results. The relationships among the blank holder forces and the thinning values at different locations were then further developed. The maps of the predicted tearing locations were then obtained and directly corresponded to the number of locations the specific blank holder forces. These maps, as established, could be directly used in a closed-loop control system enabling tearing defects to be prevented or eliminated.

Optimization of the pulsating curve for servo stamping of rectangular cup

Abstract The introduction of the servo press in recent years has opened up options for metal stamping; within this context, enhancing material formability and reducing stamping time are important goals. Focusing on a case study of rectangular cup stamping, this study optimized the pulsating curve for a servo press. First, the forming depths, thinning ratios, and forming time resulting from a pulsating curve and a crank curve were compared. Experiment results indicated that the pulsating curve could produce 92.3 % greater forming depth and an 8% smaller thinning ratio at the same forming depth as the crank curve. Next, finite element software was used to optimize the lifting velocity, press-in velocity, lifting distance, and press-in distance of the pulsating curve with forming time, thinning ratio, and forming force as single objectives. For single-objective optimization, the smaller-the-better formula of the Taguchi method was used and the analysis values of the optimal parameter combinations were compared with the optimal analysis values of nine analysis. The optimal parameter combinations produced a shorter forming time (0.06 s less), a lower thinning ratio lower (0.1425 % less), and a smaller forming force (808 N smaller). Using ANOVA and multiple regression analysis, the influence of the four process parameters on the quality characteristics and derived their mathematical relationships were calculated and their mathematical relationships derived. Next, with forming time, thinning ratio, and forming force as the quality objectives, multi-objective optimization was conducted using the Taguchi method. The grey-entropy method, and grey relational analysis were also used. Experimental verification results revealed that the grey relational grade of the optimal parameter combination was higher than those of the nine analysis. Furthermore, lifting velocity exerted the greatest influence on the multiple quality characteristics with a contribution of 55.01 %.

Center Clamp Forming of a Rectangular Cup with Bottom Edge Trimming Using a Continuous Carbon-Fiber-Reinforced Thermoplastic Sheet

Center clamp forming method has been applied to avoid wrinkles in the press forming of a rectangular cup with bottom edge trimming using a continuous woven carbon fiber-reinforced plastic plate. Trimming of a bottom edge during forming is a convenient method to obtain smooth bottom without any other successive process. But it closes the die profile that may cause fiber wrinkle. By the center clamp forming compared with free forming, it is confirmed that this is one of the methods to achieve smooth top flat surface of the cup without wrinkles. Monitoring pressure using pressure sensors elucidated pressure application process during the press forming and cooling process. Difference of the pressure holding time in the cooling process was observed between the pressure on the side plate and that on the top flat plate. Sliding descent during the cooling under constant load indicated the solidification finishing time of the thermoplastic resin.

Modelling Anisotropic Behavior of AISI 304 Stainless Steel Sheet Using a Fourth-Order Polynomial Yield Function

Following the description of an orthotropic, non-quadratic, homogenous polynomial type yield criterion, its finite element (FE) implementation is presented for the purpose of sheet metal forming analysis using an explicit time integration scheme. Then the performance of the FE implementation is firstly investigated by means of tensile test simulations of AISI (304) stainless steel sheets, and directional variation of yield strength and anisotropy factors are predicted. Next, deep drawing simulations of rectangular cups are performed, and FE computed cup thickness and flange geometry are assessed with measurements. Comparisons in both deformation processes showed that a fourth-order polynomial criterion can accurately describe the anisotropic behavior of AISI (304) stainless steel sheets.

Influence of varying sheet material properties on dry deep drawing process

Deep drawing is one of the most important processes in sheet metal forming. Conventionally, lubricants are used to reduce friction and wear. Demands for increased sustainability, environmental protection and resource efficiency motivate the realization of lubricant-free forming processes. The direct contact between tool and workpiece during dry deep drawing results in challenging tribological conditions, which cause an increase in friction and wear. Friction-reducing surface modifications of the tool such as carbon based coatings are being developed for the adaptation of the tribological conditions. The aim of this work is the simulation-based analysis of the stress spectrum for varying sheet properties for the qualification of wear-reducing surface modifications for a wide range of applications. By a simulation model for a rectangular cup, the influence of different batches of steel and aluminum materials with varying friction coefficients and mechanical properties is investigated within the framework of variant simulations. The tribological conditions in the simulation are described on the basis of friction coefficients from the strip drawing test. From the simulation results, the applicability of surface modifications for dry deep drawing is being evaluated depending on the sheet specific properties.

Back Cover: Advanced Engineering Materials 12∕2018

Advanced Engineering MaterialsVolume 20, Issue 12 1870039 Back CoverFree Access Back Cover: Advanced Engineering Materials 12∕2018 First published: 21 December 2018 https://doi.org/10.1002/adem.201870039AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract The back cover relates also to the special section. Integrated piezo elements are in 1: deep-drawn rectangular cup of sheet metal compound with comparison to the simulation result, ©Technische Universität Chemnitz; 2.die-casted aluminum plate, ©Friedrich-Alexander-Universität Erlangen- Nürnberg; and 3. fiber composite structure, ©Technische Universität Dresden. Volume20, Issue12December 20181870039 RelatedInformation

Prediction of shear fracture in multi-stage deep drawing process including ironing process for Al3003 sheet

To predict fracture caused by both tensile and shearing stresses, we applied the GISSMO (generalized incremental stress state-dependent model) in conjunction with the TFD (triaxiality failure diagram) in the finite element (FE) software LS-DYNA. Required damage parameters were determined by fitting to the load-displacement curves from tensile tests necessary to set up the TFD those obtained by corresponding FE analyses. Curve fitting was performed using the optimum design tool LS-OPT. For validation, the obtained GISSMO damage parameters were applied to the problem of rectangular cup forming for Al3003 material. Good agreement between the numerically obtained fracture locus and that observed in real forming shows that accurate shear fracture prediction is possible with the presented GISSMO-based approach.

Experimental and numerical analysis on deep drawing rectangular cups made of different anisotropic materials

Deep drawing process is a significant metal forming process used in the sheet metal forming industries. From these process most complex shapes is manufactured with less defects. Deep drawing process has many effectible process parameters from which optimum parameters must be identified so that an efficient final product will be obtained. In which effects of different sheets on deep drawing process observed for sheet metal of 0.8mm of SS304, Brass and 0.9 mm of Al. The experiments are performed by designing the deep drawing tools such as die, blank holder, and punch. Also the numerical simulations are performed for deep drawing of rectangular cups using two levels of aforesaid parameters like lubricating condition and blank material. The experiments are conducted by attaching the deep drawing tools to the Universal Testing Machine. For numerical simulation a commercial FEM code is used in which Hollomon’s power law and krupowski power law along with Hill’s 1948 yield criterions are implemented. The deep drawing setup used in the FEM code is modelled using a CAD tool by considering the modelling requirements from the literature. Strain path of 55x55mm are simulated. Punch forces and dome heights are evaluated for all the conditions. From this work the formability for different metal sheets is observed for different blank materials

Drawability of pure titanium rectangular cup

Drawability of pure titanium rectangular cup