Die Shoulder Radius Research Articles

Investigation of Sheet Thickness and Punch Force in Die Surface Angled Hydro-mechanical Deep Drawing Method

In this study, the effect of die surface angled hydro-mechanical deep drawing method (HMDDM) on sheet metal cup wall thickness and punch force was investigated as experimental and numerical analysis. In the works, 0.9 mm thick DIN EN 10130-1999 sheet metal material was used. The effect of variables on the test results was investigated by using die surface/blank holder angle, punch nose radius, die shoulder radius, chamber pressure and blank holder force as experimental parameters. Numerical analysis experiments were carried out using ANSYS 15.0 package program. Besides, experiments were performed according to the Taguchi experiment plan and L18 orthogonal array. The obtained data were analysed statistically by ANOVA analysis of variance in MINITAB 17.0 package program, and the effect of each parameter on the results was determined as a percentage. As a result, it was determined that the thinning was approximately 15% at most and the thickening was 10%.

Numerical and experimental analyzes of forming parameters of low carbon steel

Understanding sheet metal forming presses are important to reduce manufacturing costs. Thus, the best method of finding the optimum values of processing is by studying the effect of forming parameters on the behavior of formability, friction, and die radius. In this work, the deep drawing process of a low-carbon steel cup was studied and the significance of two important process parameters are investigated which are the friction coefficient and the radius of the die. The finite element method program, ANSYS, is used to study the effect of these parameters on forming load in the deep drawing process. The three ​​levels of friction coefficient are considered which are 0.08, 0.00, and 0.15, and three die shoulder radius of 4, 6, and 8 mm. The results show that the predicted behavior of the punch load coincided well with both experimental and practical behaviors and the confidence is exceeding 94%. The wrinkling defect is happening when using a high die radius, Rd=8mm although the punch load is low due to the increase in the surface area on the edge of the die.

Numerical investigation of the effect of punch corner radius and die shoulder radius on the flange earrings for AA1050 and AA1100 aluminum alloys in cylindrical deep drawing process

In aeronautic sectors, lightweight materials are very demanded in order to reduce fuel consumption. Therefore, thinning drawn cups are very recommended. Reduction of thickness led to many geometrical and physical failures that damage the final product. Since most lightweight materials had a high level of anisotropic, the presence of earrings is one of the most significant failures faced in the deep drawing process. Many functions were developed in order to control these undesirable earrings in sheet metal parts. In this paper, a simulation of a 3D cylindrical deep drawing model for AA1050 and AA1100 aluminum alloys using ABAQUS finite element software was achieved. Prediction of earing phenomenon in deep drawing process was carried out. Moreover, the impact of punch corner radius and die shoulder radius on flange earrings was analyzed and a reduction of the percentage of earring heights was investigated.

Effect of Springback on A6061 Sheet Metal Bending: A Review

Springback is defined as undesirable shape change that occurs after forming process upon unloading due to the occurrence of elastic recovery of the part. Aluminum alloy with high content of magnesium such as A6061 is preferred for high formability limit to be used in automotive industry. However, generally springback turns out to be a drawback. Many researchers have examined the springback of A6061 by considering parameters such as bent angle, die shoulder radius, blank holder force, sheet thickness, punch thickness, modulus young, yield strength, Poisson’s ratio, annealing temperature, applied load and bending operations such as V bending, deep drawing, tube bending, 3 point bending, U bending, and wipe bending. In this research, a comprehensive review is carried out to investigate process parameters and bending operations having critical impact on springback of A6061 and publications in the literature based on springback effect for A6061 studied in order to observe the number of publications by authors and the number of publications by affiliation. It is observed that sheet thickness and bent angle parameters have substantial effect on the springback. V bending and deep drawing are the commonly used bending processes. In addition, a critical contribution is presented by considering process parameters and analysis methods in order to provide a guidance for researchers for further research studies.

Evaluation of square deep drawn AA6061-T6 blank based on thinning pattern

Deep drawing can be generally described as a process of converting a metal sheet into a desired shape and geometry. Material flow and formability of the blank depends on the die and the punch geometries and it is important to predict the material behavior during square deep drawing to reduce possibility of defect and part rejection. In this research, a 3D Finite Element (FE) model is developed to simulate the square deep drawing process of an AA6061-T6 material using ANSYS Explicit Dynamics. The developed model can be used to predict the thinning pattern of the blank especially at the corner area. This research focus on the effect of design parameters namely punch corner radius (R1), punch nose radius (R2), die corner radius (R3) and die shoulder radius (R4) towards thinning pattern.

A study on a deep-drawing process with two shaping states for a fuel-filter cup using combined simulation and experiment

In this article, a deep-drawing process using a double-action hydraulic press is examined for its ability to machine the shaping deformation of a fuel-filter cup made from SPCC steel. Many researchers have studied the geometric, physical, and technological parameters of the deep-drawing process. However, most of those studies ignored the optimization parameters of the two shaping deformation states to ensure uniformity of thickness and the disappearance of wrinkling and tearing during machining. In this study, geometric and technological parameters (e.g. blank-holder force, die-shoulder radius, and radial clearance between punch and die) are optimized in both states. The deep-drawing process for a fuel-filter cup is simulated using ABAQUS software, and optimal parameters are determined by applying the Taguchi orthogonal array computation and combining it with an analysis of variance method. The numerical results are then verified with corresponding experiments. The obtained numerical and experimental results show that the die-shoulder radius is one of the most influential parameters affecting the shaping of the cup during the deep-drawing process. Moreover, the influences of technological parameters on the formability of sheet metal are finally analyzed and selected for designing and improving deep-drawing molds.

Experimental and Finite Element Results for Optimization of Punch Force and Thickness Distribution in Deep Drawing Process

Carrying out various experiments organized based on the design of experiments method, the deep drawing process is investigated entirely in this paper. The influences of eight main process parameters including punch and die radii, blank thickness, punch velocity, lubrication conditions at the interfaces of blank-die, blank-punch, and blank–blank holder as well as the blank holder force on the process outputs comprising punch force and sheet thickness variation are investigated. The analysis of variance method is considered to define the procedure by which these eight parameters be adjusted for deep drawing process to minimize the punch force and maximize the uniform thickness distribution in the products. It was found that for punch force, in addition to blank thickness, die and punch radii as well as the BHF are, respectively, the main essential parameters. Besides, blank thickness, die radius, and lubrication condition at the holder-blank interface are the most effective parameters on thickness distribution. Accordingly, initial blank thickness and die shoulder radius could be taken into account as two important parameters in deep drawing process should be set up appropriately to accomplish the minimum punch force and uniform thickness distribution together.

カップの後方押出し成形における3次元局所分岐後の劈開不安定による破断限界予測

We investigated a method of determining the geometry of the die and punch, which are not allowed to fracture in the forming process of backward extrusion of cup. On the basis of the localized bifurcation theory, it is suggested that final fracture, which is recognized as the separation of a continuum material, may occur in the shear band zone with cleavage. A newly proposed instability condition to the cleaving action in the shear band zone is applied to predict the fracture limit on the forming process. Finite element analysis of the forming process is performed to know the stress state, which is required in the theory. The experimental observation using an optical microscope is also conducted to recognize fracture occurrence during the forming process. Results show that the combination of the punch shoulder radius and the die shoulder radius ensures forming without fracture.

On the Scale Dependence of Micro Hydromechanical Deep Drawing

Tooling feature size to minimum thickness becomes small in micro scale products and its ratio affects the deformation behavior in micro sheet forming significantly. In this study, the effect of this relative tooling feature size on drawing characteristics and effects to improve the drawability, such as friction holding effect, hydrodynamic lubrication effect and compression effect by blank edge radial pressure, in micro hydromechanical deep drawing (MHDD) are investigated using plasticity theory and numerical simulation. The results show that the micro drawing characteristics in MHDD can be improved by applying counter pressure. However, the required fluid pressures for friction holding and hydrodynamic lubrication effects increase as the relative punch diameter and/or die shoulder radius to thickness decrease, although the compression effect by radial pressure on the blank edge is independent of the relative tooling feature size.

Process window calculation and pressure locus optimization in hydroforming of conical box with double concave cavities

With the enhancement in the functional integration of components and concentration on lightweight materials, complex sheet metal parts are widely used in automobile and aviation industrial clusters. Consequently, the sheet hydroforming process has become an attractive fabricating technology for forming lightweight materials and complicated products. In this research, the hydrodynamic deep drawing (HDD) process of a composite conical box with double concave cavities was investigated through theoretical analysis, numerical simulation, and process experimentation. Furthermore, the process window diagram (PWD) was calculated using the stress analytical model combining material properties with workpiece geometrical features. The influence of cavity pressure loading locus on the forming quality of the fabricated part and the deformation behavior of aluminum alloy was explored. The forming results indicated that the initial pressure, full pressure, and loading locus are the fundamental parameters directly related to the forming quality and dimensional accuracy. For the conical part with composite features, the reasonable initial pressure value is crucial for the thickness homogeneity of the double concave characteristics, whereas the magnitude of the full pressure is vital for improving the quality of the conical feature. In addition, the optimal loading locus of the cavity pressure is characterized by two turning points, which are related to the punch corner radius, die shoulder radius, blank thickness, and angle of the conical feature.

Sensitivity Analysis of Process Parameters in the Drawing and Ironing Processes

Deep drawing is one of the most important operations used in sheet metal forming. Within this, forming of cylindrical cup is one of the most widely studied deep drawing processes since it allows analysing the effect of different process parameters in phenomena such as earing, springback and ironing. In fact, during the deep drawing of a cylindrical cup the blank thickness gradually increases as the blank outer diameter is reduced to the die inner diameter, resulting in a thickness increase from a point near the bottom radius until the maximum value at the top of the cup. Therefore, if the gap between the punch and the die is not sufficiently large to allow the blank material to flow, ironing of the cup wall will occur. The ironing process typically imposes high contact forces, normal to the surface of the punch and the die, which can lead to the occurrence of galling, particularly for aluminium alloys. In this work an experimental device, adopted in previous studies, was used to analyse the influence of the lubricant conditions in the deep drawing of a cylindrical cup. The study considers an AA5754-O aluminium alloy blank with a diameter of 60 mm, which is fully deep drawn with a 33 mm diameter punch. Due to the forming conditions, the cup is deep drawn and ironing of the cup wall also occurs. The experimental tests were performed considering different amounts of lubricant in the blank surfaces in the contact with the die and with the blank-holder in order to better understand the influence of these tools on the process. The experimental study was complemented with numerical simulations, exploring the conditions induced by the ironing operation, quite challenging for the numerical simulation of the process using the finite element method. Besides the influence of the contact with friction conditions in the forming process (i.e. punch force evolution, thickness distribution along the cup wall and contact pressure), the influence of the die shoulder and inner radius were also analysed.

Sensitivity analysis and statistical process optimisation of deep drawing of AA 6061 sheet material

Deep drawing, besides its importance as a forming process, also serves as a basic test for sheet metal formability. The elastic deformation within the overall amount of deformation is not desired and leads to springback in the drawn components. This affects the dimension and shape of the formed cups. Fundamental understanding of variation of the process parameters has become essential for accurate rapid design of tooling and processes in early design stage. Therefore, in the present study, the effect of parameters such as the die shoulder radius, punch nose radius and the blank holder force on the deep drawing of AA 6061 aluminium alloy is studied and mathematical model was developed using response surface methodology. The parameters were optimised for minimum springback. Sensitivity analysis was carried out to evaluate the effects of each process parameter on springback. The optimal values of die shoulder radius, punch nose radius and blank holder force for minimising the springback were found to be 3 mm, 3 mm and 6 kN respectively.

Influence of variables in deep drawing of AA 6061 sheet

Deep drawing is one of the most important processes for forming sheet metal parts. It is widely used for mass production of cup shapes in automobile, aerospace and packaging industries. Cup drawing, besides its importance as forming process, also serves as a basic test for the sheet metal formability. The effect of equipment and tooling parameters results in complex deformation mechanism. Existence of thickness variation in the formed part may cause stress concentration and may lead to acceleration of damage. Using TAGUCHI's signal-to-noise ratio, it is determined that the die shoulder radius has major influence followed by blank holder force and punch nose radius on the thickness distribution of the deep drawn cup of AA 6061 sheet. The optimum levels of the above three factors, for the most even wall thickness distribution, are found to be punch nose radius of 3 mm, die shoulder radius of 8 mm and blank holder force of 4 kN.

베릴륨동 극박판의 드로잉 성형성과 품질특성 연구

The present study is focused on the deep drawability and product qualities of ultra thin beryllium copper sheet metal. The goal of this research is to investigate the limit drawing ratio in deep drawing of ultra thin beryllium copper metal. For the experiment, beryllium copper(C1720, <TEX>$50{\mu}m$</TEX> in thickness) is used. Tensile test are also carried out to find out the material properties. Deep drawing experiments are carried out in Universal Testing Machine(UTM) to obtain limit drawing ratio. Deep drawing tests are carried out for various specimen sizes. Teflon film is used as a lubricant and constant blank holding force is imposed. Sheet thickness and surface hardness are measured along radial direction after deep drawing. Thickness is measured using optical microscope. For beryllium copper(C1720), the maximum LDR of 2.4 is obtained when the die shoulder radius is 20 or 30 times of sheet thickness.

An elasto-plastic finite element analysis of the sheet metal stretch flanging process

The incremental updated Lagrangian elasto-plastic finite element method (FEM) was employed in this study to analyse the stretch flanging of circular plates with a pre-determined smaller hole at the centre of the sheet metal. An extended r min technique was employed such that each incremental step size is determined not only by the yielding of an element Gaussian point, but also by the change in the boundary condition along the tool-sheet interface. The experimental results, using a low-carbon (BA-CQ2) sheet plate with a thickness of 1.0 mm, have been obtained and compared with the corresponding theoretical results. It was found that the flange thickness does not always decrease monotonically from the die shoulder to the flange edge. Reducing the punch diameter and increasing the flange height significantly reduced the flange thickness. Web width does not influence the thickness distribution of the flange. The tendency of flange thickness to thin decreases as punch diameter increases. The reduction of thickness at the die shoulder depends on the die shoulder radius. Simulation results of punch load of stretch flanging, the deformed geometry, and the distribution of thickness are compared with experimental data and found to satisfactorily agree.

Optimisation des paramètres du procédé de pliage en tombé de bord par plan d'expériences numérique et méthode des surfaces de réponse

Bending has significant importance in sheet metal product industry such as automotive security parts. The present work presents a general framework of numerical simulation of wiping die bending processes. A Computer Aided Design (CAD) for bending process using finite element method is presented which consists of metal forming operation characterised by complete material deformation. In this paper, we describe robust methods of predicting load bending evolution and stress distribution of specimens in 3D modelling subjected to bending deformation. The values are determined in a local frame according to elements deformation. A numerical approach of the problem requires a comprehensive finite element modelling due to the diversity of physical phenomena involved, such as friction effects, material and geometrical non-linearities, large plastic deformation and material failure. Lemaitre's material damage within the sheet was taken into account in the simulation during forming process. The interface contact law is defined by Coulomb's friction model and the elastoplastic constitutive laws are integrated by means of an incremental formulation which has been implemented in the finite element code ABAQUS. The influence of punch/die clearance and die shoulder radius are analysed. An algorithmic loop programmed in Script language of ABAQUS was retained to investigate the mechanical responses of the part for each case of parameters combination. The punch load and the distribution of stresses could be predicted in view of optimising the value of the main parameters of the process. An optimisation technique based on the use of Design Of Experiments (DOE) and Response Surface Methodology (RSM) is proposed in the work in order to minimise the tensile and compressive stresses found in the most damaged zone during the bending operation. Numerical results have shown the robustness of the proposed model and are discussed in more detail and enlightened by corresponding plots.

Optimisation of springback predicted by experimental and numerical approach by using response surface methodology

Bending has significant importance in the sheet metal product industry. Moreover, the springback of sheet metal should be taken into consideration in order to produce bent sheet metal parts within acceptable tolerance limits and to solve geometrical variation for the control of the manufacturing process. Nowadays, the importance of this problem increases because of the use of sheet-metal parts with high mechanical characteristics (high strength low alloy steel). This work describes robust methods of predicting springback of parts in 3D modelling subjected to bending and unbending deformations. Also the effects of tool geometry in the final shape after springback are discussed. The first part of this paper presents the laboratory experiments in wiping die bending, in which the influence of process variables, such as die shoulder radius, punch-die clearance, punch nose radius and materials properties are discussed. The second part summarises the finite element analysis by using ABAQUS software and compares these results with some experimental data. The final results of the FEM simulation are in good agreement with the experimental ones. An optimisation methodology based on the use of experimental design method and response surface technique is proposed in the third part of this paper. This makes it possible to obtain the optimum values of clearance between the punch and the die and the optimum die radius, which can reduce the springback without cracking and damage of product.

Residual Stresses due to Deep-Drawing of Pre-Coated Aluminum-Alloy Sheets

In this study, we examined how the press formability of A1 alloys sheets and the generation of residual stresses was influenced by pre-coating resins, lubricants, die shoulder radius, the punch shoulder radius, and so on. The use of a pre-coated layer offers advantages by preventing direct contact between sheet metal and the face of the die, and also by enabling the use of volatile oil lubricants that keep the factory environment cleaner. The circumferential residual stress (σC ) of a cup becomes lower when the lubricant is less effective, and when the die shoulder radius is smaller.

Optimisation of Springback Predicted by Experimental and Numerical Approach by Using Response Surface Methodology

Bending has significant importance in the sheet metal product industry. Moreover, the springback of sheet metal should be taken into consideration in order to produce bent sheet metal parts within acceptable tolerance limits and to solve geometrical variation for the control of manufacturing process. Nowadays, the importance of this problem increases because of the use of sheet-metal parts with high mechanical characteristics (High Strength Low Alloy steel). This work describes robust methods of predicting springback of parts in 3D modelling subjected to bending and unbending deformations. Also the effects of tool geometry in the final shape after springback are discussed. The first part of this paper presents the laboratory experiments in wiping die bending, in which the influence of process variables, such as die shoulder radius, punch-die clearance, punch nose radius and materials properties were discussed. The second part summarises the finite element analysis by using ABAQUS software and compares these results with some experimental data. It appeared that the final results of the FEM simulation are in good agreement with the experimental ones. An optimisation methodology based on the use of experimental design method and response surface technique is proposed in the third part of this paper. That makes it possible to obtain the optimum values of clearance between the punch and the die and the optimum die radius which can reduce the springback without cracking and damage of product.

Prediction and elimination of springback in straight flanging using computer-aided design methods: Part 2: FEM predictions and tool design

Part 1 of this two-part paper presents the laboratory experiments on straight flanging, in which the influence of process variables, such as die shoulder radius, punch-die clearance, punch nose radius, pad force and material properties were discussed. This second part summarizes the FEM predictions for flanging and compares these results with some experimental data. Furthermore, flanging with coining to reduce springback has been investigated and evaluated by FEM for better dimensional control in flanging and hemming processes.