Sheet Metal Processing Research Articles

In-situ-measurement of the friction coefficient in the deep drawing process

The surface texture plays an important role in the tribological behaviour of deep drawn components. It influences both the process of sheet metal forming as well as the properties for post processing, such as paint appearance, bonding, or corrosion tendency. During the forming process, the texture of the sheet metal and therefore its friction coefficient, changes due to process related strains. This contribution focuses on the development and validation of a tool to investigate the friction coefficient of the flange region of deep drawn components. The influence of biaxial strain on the friction coefficient will be quantified through a comparison of the experimental results with a conventional friction test (stand). The presented method will be applied on a cup drawing test, using a segmented and sensor-monitored blankholder. This setup allows the measurement of the friction coefficient in-situ without simplification of the real process. The experiments were carried out using DX 56D+Z as sheet metal and PL61 as lubricant. The results show a characteristic change in the friction coefficient over the displacement of the punch, which is assumed to be caused by strain induced change of the surface texture.

The Effect of the Use of Technological Lubricants Based on Vegetable Oils on the Process of Titanium Sheet Metal Forming

Abstract The paper evaluates the drawability of titanium sheet metal Grade 2, with the focus on friction conditions that are present in the sheet metal forming process. The study aims to present the results of the examinations of the friction coefficient during a strip drawing test. The focus of the experiment was on lubricants based on vegetable oils i.e. rapeseed oil, sunflower oil and olive oil. Boric acid was used to improve the lubricating properties of vegetable oils. The results of numerical simulations of the process of forming a cover with stiffening components made of grade 2 titanium sheet metal was also presented. The numerical simulation was carried out using the FEM method with PAMStamp 2G software. The effect of conditions of friction between the sheet metal and tool parts and pressure force of the blank holder on the forming process were investigated. Numerical calculations were performed with consideration for the phenomenon of material strain hardening and anisotropy of plastic properties of the sheet metal formed. The analysis of the deformations and reduction in wall thickness of the drawn parts can be used for determination of the effect of changes in selected parameters on the process of drawn part forming. The quality of drawn parts was assessed based on the shape inaccuracy determined during simulation of forming. The inaccuracy depended on the conditions of the process and strength properties of the titanium sheet metal.

Shape accuracy analysis of multi-point forming process for sheet metal under normal full constrained conditions

In order to study the shape accuracy of multi-point forming (MPF) process for sheet metal under normal full constrained conditions, the in-depth analysis of shape accuracy of workpieces in multi-point forming with individually controlled force-displacement (MPF-ICFD) process is conducted in this paper by combining experiment, theoretical analysis and numerical simulation. The influences of normal force, material thickness and material properties on the shape accuracy of the feature surface are studied, and the shape accuracy characteristics of the sheet under different parameters are obtained. Afterwards, the stress and strain characteristics of sheets are obtained by numerical simulation. Finally, the effect of normal force on shape accuracy was revealed by establishing a mechanical model of the sheet metal under normal full constrained conditions. Moreover, the amount of springback reduction in MPF-ICFD is defined quantitatively. Compared with the normal unconstrained conditions, the shape accuracy of sheet metal is improved significantly under normal full constrained conditions. The stress and plastic deformation are more uniform and the amount of springback is smaller. For Q 295 steel plate with thickness of 2.0 mm, the difference between the maximum value and the minimum value of the reaction force of punch decreases from 4515.9 N to 1475 N when the forming force is 2500 N. Besides, the bending moment of the sheet on the unit width decreases from 357.9 N • mm to 328.1 N • mm. The average shape error E rr and the amount of springback Δk decreases by 60.05% and 16.03%, respectively.

Study of fracture behavior for anisotropic 7050-T7451 high-strength aluminum alloy plate

The anisotropic ductile fracture behavior is significant to forming process of sheet metal. A modified elliptical fracture criterion incorporating Hill48′s criterion was applied to characterize the ductile fracture behavior of anisotropic plate. Then the fracture loci and surfaces of anisotropic AA7050-T7451 plate in the different stress spaces were studied to analyze the effect of plasticity anisotropy on fracture loci. The law of forming capability for anisotropic AA7050-T7451 plate with different stress triaxiality and Lode parameter was revealed. In order to validate the accuracy of the proposed ductile fracture model, the analyses of failure predictions for uniaxial tensile and pure shear tests at 0°, 45°, and 90° with respect to the rolling direction had been carried out by experiments and finite element method (FEM). The failure predictive results from FEM are in good agreement with the experimental and theoretical ones. It turns out that the fracture loci of at Le=−1 are sensitive to the material orientations. Meanwhile, the formability of AA7050-T7451 along 90° direction on tensile strain states is very poor.

Direct Molten Metal Rolling of Aluminum Alloy A3003

This paper describes a production process for aluminum alloy sheet metal. Direct molten metal rolling, in other words strip casting process for aluminum alloy A3003 sheet was operated. Strip casting process is able to produce the metal sheet from molten metal directly. Thus this process has possibility of improving the productivity of sheet because of shortening operation of rolling. In this study, experimental device was designed for direct molten metal rolling. Aluminum alloy A3003 was chosen. A3003 is for aluminum can body, and the sheet required the high productivity. The effect of roll speed on the produced strip surface and strip thickness was investigated. Roll speed were 1, 2 and 3 m/min. It was possible to produce A3003 strip by direct rolling at the conditions of roll speed 3 m/min, pouring temperature 700 °C, solidification length 15 mm and nozzle exit width 15 mm. Obtained strip surface was flatten and had a metallic luster.

Cloud manufacturing system for sheet metal processing

Cloud computing is changing the way industries and enterprises run their businesses. Cloud manufacturing is emerging as an approach to transform the traditional manufacturing business model, while helping the manufacturer to align production efficiency with its business strategy, and creating intelligent factory networks that enable collaboration across the whole enterprise. Many production planning and control (PPC) problems are essentially optimisation problems, where the objective is to develop a plan that meets the demand at minimum cost or maximum profit. Because the underlying optimisation problem will vary in the different business and operation phases, it is important to think about optimisation in a dynamic mechanism and in a number of interlinked sub-problems at the same time. Cloud manufacturing has the potential to offer decision support as a service and medium of communication in PPC. To solve these problems and produce collaboration across the supply chain, this paper provides an overview of the state of the art in cloud manufacturing and presents a model of cloud-based production planning and production system for sheet metal processing.

A methodology for the identification of strategic technological competences: An application in the sheet metal equipment industry

This paper proposes a technology foresight methodology based on the development of a complementary approach to the Delphi method that enables the identification of strategic technological competences, and presents its application in a sheet metal processing equipment manufacturer. The proposed methodology takes into consideration synergies between future events through a modified QFD matrix, and the application involved a panel of experts from industry and academia. The proposed methodology can benefit organizations by promoting a homogeneous perspective on existing relationships between external drivers and technology diffusion. This study contributes for the understanding of the links between foresight and technology strategy formulation. Further implementations in industrial environments should be performed to refine the methodology and increase the confidence level on the expected results that these findings can signify.

Optimization of CO2 laser cutting parameters on Austenitic type Stainless steel sheet

Thin AISI 316L stainless steel sheet widely used in sheet metal processing industries for specific applications. CO2 laser cutting is one of the most popular sheet metal cutting processes for cutting of sheets in different profile. In present work various cutting parameters such as laser power (2000 watts-4000 watts), cutting speed (3500mm/min – 5500 mm/min) and assist gas pressure (0.7 Mpa-0.9Mpa) for cutting of AISI 316L 2mm thickness stainless sheet. This experimentation was conducted based on Box-Behenken design. The aim of this work is to develop a mathematical model kerf width for straight and curved profile through response surface methodology. The developed mathematical models for straight and curved profile have been compared. The Quadratic models have the best agreement with experimental data, and also the shape of the profile a substantial role in achieving to minimize the kerf width. Finally the numerical optimization technique has been used to find out best optimum laser cutting parameter for both straight and curved profile cut.

Combination of Hot Forming with CRP and Rapid Cooling to Obtain Enhanced Formability in Thermomechanical Treatment

ABSTRACTIn sheet metal forming, rapid cooling of austenitized steel and CRP (cushion-ram pulsation) results in an optimized formability. An analysis is conducted regarding the influence of a stepwise deep drawing process of manganese-boron steel 22MnB5, using an oscillating ram-cushion motion at simultaneous cooling. The stops occurring in stepwise forming provide sufficient time for softening and recovery of forming properties. The microstructure can be adjusted by controlled cooling. In order to examine the newly developed process in more detail, FE simulation is applied. Thus, relevant process and material parameters can be determined. The considered values are required for profound experiments using the forming simulator BAEHR DIL 805 A/D. The softening behavior at defined forming temperatures due to CRP are examined. The experimental results of softening at distinctive temperatures provide a basis for the combined processes of stepwise hot sheet metal forming and simultaneous cooling.

精密板金加工のスケジューリング問題のためのハイブリッド解法

精密板金加工のスケジューリング問題のためのハイブリッド解法

On the influence of Seebeck coefficients on adhesive tool wear during sheet metal processing

During every kind of sheet metal manufacturing process, thermoelectric voltages and currents result from a temperature rise between tool and sheet metal. Their influence on the process and tool wear behavior has been investigated insufficiently so far. Therefore, Seebeck coefficients, representing thermoelectric properties, have been determined for several materials. The correlation between different Seebeck coefficients of tool, respectively, sheet materials and arising thermoelectric currents are exemplarily shown by an instantaneous measurement during blanking. An adequate material selection with regard to thermoelectric properties reduced adhesive wear to 22%. The obtained results improve the fundamental understanding of wear causing interactions.

Finishing Surface After Regeneration with Laser Cladding

This article has presented the results of experimental research concerning the regeneration process of flat sheet metal made of C45 steel, which is difficult to weld. The regeneration process included filling the material defect of 20×20×0.75mm with laser cladding with a powder form additive. Rough machining of the surface with cladding has been conducted at a vertical milling center, while the finishing work was performed with a surface grinder. The analysis of obtained results has been performed on the basis of measurements of selected parameters concerning the geometrical structure of the regenerated surface treated with machining.

An Exploratory Study for Analyzing the Energy Savings Obtainable by Reshaping Processes of Sheet Metal Based Components

Producing materials causes about 25% of all anthropogenic CO2 emissions. Reshaping could be one of the most efficient strategy to foster material reuse and lower the environmental impact due to material production. Sheet metal forming processes can be applied to reshape sheet metal based component. This research field is still almost unexplored and the actual environmental impact saving potential has not been quantified. The present paper aims at starting to cover this research gap, a modeling effort to quantify the environmental impact saving of reshaping is proposed. Primary energy demand for conventional recycling and reshaping are quantified and compared. Primary energy savings obtainable for an aluminum hood reshaping for different production scenarios are quantified. Results reveals that reshaping could lead to significant energy saving with respect to conventional recycling route based on remelting. The present research is a first step to explore advantages and disadvantages of reshaping processes and to understand actual applicability of such a material reuse approach.

Coevolutionary Genetic Algorithm Based Nesting Scheduling for Sheet Metal Processing

Coevolutionary Genetic Algorithm Based Nesting Scheduling for Sheet Metal Processing

A numerical simulation of thermodynamic processes for cryogenic metal forming of aluminum sheets and comparison with experimental results

Forming at cryogenic temperatures provides a significant improvement in formability of aluminum sheets. This offers the potential for light, complex and highly integrated one-piece components to be produced out of aluminum alloys at sub-zero temperatures. This would allow weight reduction, environmental conservation and cost reduction of a car body to give one example in the automotive industry. For temperature supported processes special forming tools and cooling strategies are required to be able to reach and maintain process stability. Time dependent numerical simulations of the thermodynamic processes of cryogenic sheet metal forming covering all aspects of heat transfer through conduction, convection and radiation play a vital role in the design and development of future tools and are presented for several geometries. Cooling (and heating) strategies (including selection of the number of cooling loops and their relative positioning) in a Nakajima testing tool were evaluated using computational fluid dynamics. These simulations were performed with static and transient solvers to demonstrate the extraction of tool surface temperature distributions on different forming tool geometries. Comparisons of predicted temperature characteristics of an aluminum sheet and experimentally determined temperature distributions were made. The temperature distribution of the surface of an aluminum sheet could be predicted with high accuracy. Further, the influence of the tool size on the parameters temperature transfer times and temperature homogeneity was examined by introducing a scaling factor of the forming tool. It became evident, that the size ratio between the aluminum sheet thickness and the tool contact area has a major influence on these parameters. Finally, further simulations were carried out using a forming tool for representative shaped car body components to show the effects of multiple cooling loops and different cooling strategies.

The Experimental Investigation of Springback in V-Bending Using the Flexforming Process

The flexforming process is a sheet metal forming method that uses hydraulic fluid pressure and a rubber diagram to form sheet metal with a die. This study, for the first time, experimentally investigates the factors affecting the springback resulting from the bending of copper and brass sheet metal materials in V-bending dies using the flexforming process. Additionally, the formability during the V-bending method was experimentally investigated by using thin, high-pressure-resistant rubber membranes instead of the thick ones commonly used in the flexforming processes. The process parameters in the experimental studies were determined to be: holding time (0, 5 and 10 s), bending angle (\(15^{\circ }, 30^{\circ }, 45^{\circ }, 60^{\circ }, 75^{\circ }\) and \(90^{\circ })\) and fluid pressure (10, 12 and 14.4 MPa). Sheet metals were formed in V-bending dies by both flexforming and conventional bending processes to compare the performance of the flexforming process against the conventional bending process. Springback values in the parts formed using the flexforming process for copper and brass sheet metals were determined to be 39.06 and 41.42% less, respectively, than those formed by the conventional bending method. Surface flaws occurring in the parts formed by the conventional bending method were not observed in the parts formed using the flexforming process. The springback was also estimated by using fuzzy logic based on unexecuted break-test parameters. When the outputs of the fuzzy logic system were compared with the experimental results, it was observed that the results were substantially similar.

MAGNETIC PULSED PROCESSING OF METALS FOR ADVANCED TECHNOLOGIES OF MODERNITY – A BRIEF REVIEW

The aim of the article is dedicated to the brief review of the main achievements of the advanced technologies with usage of the energy of the pulsed magnetic fields. Originality. The new suggestions are represented. They are based on the results of development of the new scientific direction in area of the magnetic pulsed processing of thin-walled sheet metals when a penetration of the acting fields is quite significant. The known traditional approaches based on the skin-effect in electrodynamics and were successfully implemented. Methodology of the analysis consist of careful theoretical and practical experiments review and its future development. Results of the research based on the existing experimental approbation were presented visually with the description followed The known approaches to solution actual production problems based on the skin-effect in electrodynamics are described. Practical value. The first of practical propositions is related to stamping of the drawing the printed circuit boards on the cooper foil with thickness about ~50 mkm. This operation is realizing by the forces of magnetic pressure directly without any supplements introduction. The second consists in usage the magnetic pulsed attraction for external removing the dents in the car body. This operation does not demand disassembling of elemental base and allows preserving the paint of coverings. Both of these technologies could to minimize the working time, to decries the volume of the waste products and to make the manufacturing existed much cheaper. References 10, figures 3.

A cloud based job sequencing with sequence-dependent setup for sheet metal manufacturing

This paper presents a prototype system of sheet metal processing machinery which collects production order data, passes current information to cloud based centralized job scheduling for setup time reduction and updates the production calendar accordingly. A centralized cloud service can collect and analyse production order data for machines and suggest optimized schedules. This paper explores the application of sequencing algorithms in the sheet metal forming industry, which faces sequence-dependent changeover times on single machine systems. We analyse the effectiveness of using such algorithms in the reduction of total setup times. We describe alternative models: Clustering, Nearest Neighbourhood and Travelling Salesman Problem, and then apply them to real data obtained from a manufacturing company, as well as to randomly generated data sets. Based on the prototype implementation clustering algorithm was proposed for actual implementation. Sequence-dependency increases the complexity of the scheduling problems; thus, effective approaches are required to solve them. The algorithms proposed in this paper provide efficient solutions to these types of sequencing problems.

Numerical prediction of springback and ductile damage in rubber-pad forming process of aluminum sheet metal

Rubber forming is a sheet metal forming process using flexible punch or die. In this paper, finite element method is introduced to analyze rubber-pad forming process of aluminum sheet metal. An elasto-plastic constitutive model with J2 yield criterion and mixed non-linear isotropic/kinematic hardening coupled with Lemaitre's ductile damage has been adopted during flexible forming operation. To model rubber material, a Mooney-Rivlin theory is used in the finite element simulation. A stamping of aluminum sheet metal with soft punch is simulated. A fully coupled elasto-plastic damage model is implemented in ABAQUS/Standard software via UMAT subroutine to study the effect of some key process parameters like hardness of rubber, type of rubber on the variation of the thickness, the springback and damage of aluminum sheet metal.

On the fracture prediction of 304L stainless steel sheets utilizing different hardening models

Fracture prediction is one of the challenging problems in sheet metals. Forming limit curves at fracture (FLCF), as a tool to determine fracture in sheet metal processes, are obtained through the use of numerical analyses. As one of the approaches, the ductile fracture criteria (DFCs) represent the fracture initiation of the sheets formed by different loading histories. In this study, the effects of three different hardening models on different DFCs to predict the fracture for stainless steel 304L have been investigated. The results show that most of DFCs work better in the region ɛ2 <0 especially with the kinematic hardening model. However, for the region ɛ2>0 where the stretching conditions are dominant, none of them could precisely estimate the fracture initiation.