scholarly journals Investigation of Effects of Material Dimensions on Wrinkling in Flexforming Process

2021 ◽  
Author(s):  
Gürhan Yılgın ◽  
Oguzhan Yilmaz ◽  
Fahrettin Ozturk ◽  
Hasan Ali Hatipoglu
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Flexible Manufacturing ◽  
Research Work ◽  
Sheet Thickness ◽  
Production Costs ◽  
Material Condition ◽  
Material Conditions ◽  
Experimental Findings

Abstract Sheet metal forming processes are very common manufacturing and leading processes in automotive and aerospace industries. Flexforming is one of the sheet metal forming processes which is preferable due to its flexible manufacturing capabilities and its ability to produce multiple parts simultaneously. Convex contoured shaped parts are very much used in aerospace structures which are mostly produced by flexforming. Wrinkling is a characteristic defect for those kinds of parts. Prediction of wrinkling before manufacturing is highly crucial in order to reduce scrap rates, labor time, and other unexpected costs. In this research work, extensive amounts of experiments are conducted on flexforming press, and the process parameters such as material condition, contour radius, flange length, and material thickness which induce wrinkling are investigated in detail. Results have shown that sheet thickness is the most effective parameter, and as the sheet thickness is increased, wrinkling tendency is reduced extensively. Besides, increasing convex contour radius decreases wrinkling occurrence. Experimental findings are then used to generate wrinkling limit diagrams in which safety and failure zones are specified for different material conditions and sheet thicknesses. The developed diagrams might help to designer who can design defect free parts, reduce scrap rates, and reduce production costs significantly.

Preliminary Studies on the Determination of FLD for Single Point Incremental Sheet Metal Forming

2012 ◽  
Vol 504-506 ◽  
pp. 863-868 ◽  
Author(s):  
Miklos Tisza ◽  
Péter Zoltán Kovács ◽  
Zsolt Lukács
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
New Technologies ◽  
Single Point ◽  
Research Work ◽  
Dimensional Accuracy ◽  
Forming Limit ◽  
Incremental Sheet Metal Forming

Development of new technologies and processes for small batch and prototype production of sheet metal components has a very important role in the recent years. The reason is the quick and efficient response to the market demands. For this reasons new manufacturing concepts have to be developed in order to enable a fast and reliable production of complex components and parts without investing in special forming machines. The need for flexible forming processes has been accelerated during the last 15 years, and by these developments the technology reaches new extensions. Incremental sheet metal forming (ISMF) may be regarded as one of the promising developments for these purposes. A comprehensive research work is in progress at the University of Miskolc (Hungary) to study the effect of important process parameters with particular emphasis on the shape and dimensional accuracy of the products and particularly on the formability limitations of the process. In this paper, some results concerning the determination of forming limit diagrams for single point incremental sheet metal forming will be described.

scholarly journals Effect of Process Parameters and Preheating Temperature on Surface Roughness and Thickness Distribution in Hole Flanging using Incremental Sheet Metal Forming

2019 ◽  
Vol 8 (12S2) ◽  
pp. 84-87
Keyword(s):  
Surface Roughness ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Thickness Distribution ◽  
Research Work ◽  
Preheating Temperature ◽  
Incremental Sheet Metal Forming ◽  
Best Parameter ◽  
Hole Flanging

Incremental Sheet metal forming is a die less method of forming which offers high formability. In this research work; effect of step depth, tool rotation speed and preheating temperature on surface roughness and thinning of flange wall is investigated in hole flanging using incremental forming. The parameter optimization is carried out by Taguchi method. Grey relational analysis is carried out to obtain best parameter combination.

Tribological Behaviour of PVD Coatings for Sheet Metal Forming Tools: Laboratory and Industrial Evaluation

2012 ◽  
Vol 504-506 ◽  
pp. 543-548 ◽  
Author(s):  
Francesco Sgarabotto ◽  
Andrea Ghiotti
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Vapour Deposition ◽  
New Technology ◽  
Research Work ◽  
Chemical Vapour ◽  
Tribological Behaviour ◽  
Wide Range ◽  
Forming Tools

In the last decades, Physical Vapour Deposition (PVD) and Chemical Vapour Deposition (CVD) processes have been significantly improved and optimized for the applications on dies for sheet metal forming processes. However, due to the different contact conditions at dies-blank interfaces, and the wide range of applied contact pressures, the selection of the correct coating may be still affected by trials-and-error approaches. Although many methods to evaluate the tribological performances of such coatings can be found in scientific literature, they often suffer of limitations in reproducing the interface conditions typical of industrial processes. The objective of the present research work is to investigate the tribological behaviour of two coatings deposited by PVD magnetron sputtering technique. Both investigations in laboratory and industrial conditions were performed: the former to evaluate their tribological characteristics, the latter to test the performances of coatings in production lines. The results, in terms of wear resistance, outline the comparison of the new technology with the performances of traditional dies.

The Effect of Anisotropy on Spring-Back of CK67 Steel Sheet in L-Dies Bending Processes

2011 ◽  
Vol 291-294 ◽  
pp. 672-675
Author(s):  
Jafar Bazrafshan ◽  
A. Gorji ◽  
A. Taghizadeh Armaky
Keyword(s):  
Numerical Simulations ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Steel Sheet ◽  
Elastic Recovery ◽  
Sheet Thickness ◽  
Bend Angle ◽  
Spring Back ◽  
Geometric Changes

One of the most sensitive features of sheet metal forming processes is the elastic recovery during unloading, called spring-back, which leads to some geometric changes in the product. This phenomenon will affect bend angle and bend curvature, and can be influenced by various factors. In this research, the effects of sheet thickness and die radiuses an sheet anisotropy on spring-back in L-die bending of CK67 steel sheet were studied by experiments and numerical simulations.

scholarly journals Blank shape optimization considering 3D space targets for external and internal boundaries in sheet metal forming processes

2021 ◽  
Author(s):  
Hamidreza Gharehchahi ◽  
Mohammad Javad Kazemzadeh-Parsi ◽  
Ahmad Afsari ◽  
Mehrdad Mohammadi
Keyword(s):  
Sheet Metal ◽  
Optimum Design ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Production Costs ◽  
Internal Boundary ◽  
Optimum Shape ◽  
Plastic Behavior ◽  
3D Space ◽  
Blank Shape

Abstract The optimum design of an initial blank shape in sheet metal forming processes is an important step in many industries, especially automobile manufacturers because it reduces production costs and material waste. To the best of our knowledge, no research has been conducted on the blank shape designs based on 3D space target contours. Moreover, the present study considers parts with internal boundaries and optimum design of the internal boundary, which are among the innovations of this research. By following the iterative simulation-based optimization process, a special updating algorithm was proposed to modify the blank geometry in each iteration and reach the optimum shape. The sheet forming was severely nonlinear, due to plastic behavior, large deformations, and frictional contact surfaces. Therefore, the updating formula should be robust enough to be insensitive to the initial guess for the blank. To evaluate the proposed updating formula, some numerical examples were solved and the results were presented. Finally, the robustness of the proposed algorithm was investigated in these numerical experiences, by considering different geometries, target contours, internal boundaries, and initial guesses. The present study reveals that the proposed algorithm can be effectively used to solve blank optimization problems for the deep drawing process.

Assessment of Damage Models in Sheet Metal Forming for Industrial Applications

2011 ◽  
Vol 473 ◽  
pp. 482-489
Author(s):  
Maria Doig ◽  
Karl Roll
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Damage Model ◽  
High Strength ◽  
Industrial Applications ◽  
Production Costs ◽  
Model Parameters ◽  
Damage Prediction ◽  
Damage Models

Due to increasing demands to reduce C02-emission and to augment occupant’s safety new modern materials are developed ongoing. Because of relatively low production costs, high strength and simultaneously good formability the advanced high strength steels (AHSS) are applied among others for the lightweight design of body-in-white components in the automotive industry. Their already mentioned properties follow from the presence of mixed mild and hard ferrous phases. Due to this multiphase microstructure of the most AHSS steels, a complex material and damage behavior is observed during forming. The damage grows in a ductile manner during plastic flow and the cracks appear without necking. They are often characterized as the so called shear cracks. The damage predictions with standard methods like the forming limit curve (FLC) lack accuracy and reliability. These methods are based on the measurement of linear strain paths. On the other hand ductile damage models are generally used in the bulk forming and crash analysis. The goal is to prove if these models can be applied for the damage prediction in sheet metal forming and which troubles have to be overcome. This paper demonstrates the capability of the Gurson-Tvergaard-Needleman (GTN) model within commercial codes to treat industrial applications. The GTN damage model describes the existence of voids and they evolution (nucleation, growth and coalescence). After a short introduction of the model the finite element aspects of the simulative damage prediction have been investigated. Finally, the determination of the damage model parameters is discussed for a test part.

scholarly journals Single and ensemble classifiers for defect prediction in sheet metal forming under variability

2019 ◽  
Vol 32 (16) ◽  
pp. 12335-12349 ◽  
Author(s):  
M. A. Dib ◽  
N. J. Oliveira ◽  
A. E. Marques ◽  
M. C. Oliveira ◽  
J. V. Fernandes ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Process Parameters ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Sheet Thickness ◽  
Machine Learning Techniques ◽  
Data Sets ◽  
Ensemble Classifiers ◽  
Ensemble Models ◽  
Using Data

AbstractThis paper presents an approach, based on machine learning techniques, to predict the occurrence of defects in sheet metal forming processes, exposed to sources of scatter in the material properties and process parameters. An empirical analysis of performance of ML techniques is presented, considering both single learning and ensemble models. These are trained using data sets populated with numerical simulation results of two sheet metal forming processes: U-Channel and Square Cup. Data sets were built for three distinct steel sheets. A total of eleven input features, related to the mechanical properties, sheet thickness and process parameters, were considered; also, two types of defects (outputs) were analysed for each process. The sampling data were generated, assuming that the variability of each input feature is described by a normal distribution. For a given type of defect, most single classifiers show similar performances, regardless of the material. When comparing single learning and ensemble models, the latter can provide an efficient alternative. The fact that ensemble predictive models present relatively high performances, combined with the possibility of reconciling model bias and variance, offer a promising direction for its application in industrial environment.

Active Material Flow Control during High-Pressure Sheet Metal Forming

2005 ◽  
Vol 6-8 ◽  
pp. 377-384 ◽  
Author(s):  
Peter Groche ◽  
C. Metz
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Material Flow ◽  
High Pressures ◽  
Active Material ◽  
Sheet Thickness ◽  
Blank Holder ◽  
Rotationally Symmetric ◽  
Material Flow Control

During forming of non-rotationally symmetric sheet metal parts at high pressures nonuniform deformation conditions arise in the flange area. These deformations vary in height and consequently lead to heterogeneous sheet thickness distributions. When using semi-rigid tools, high clamping forces are necessary in order to compensate for the developing sheet thickness variations in the flange area and to avoid leakages of the system or wrinkling. Moreover, the heterogeneous distribution of the clamping force is strengthened by press inaccuracies. This results in a higher surface pressure distribution on one side of the flange and finally in a non-uniform material flow out of the flange area. The development of a segmented active-elastic blank holder enables an active material flow control of the flange movement during sheet metal forming at high pressures. The local elasticity of the active-elastic blank holder is based on an optimized layout of the local tool rigidity. For this purpose, different grooves were integrated below the blank holder surface. This paper provides an overview of the developed technology, advantages with regard to the part’s quality, and recent results comparing the production of non-rotationally symmetric parts with segmented active-elastic tools vs. semi-rigid tools.

scholarly journals Effect of Process Parameters and Preheating Temperature on Surface Roughness and Thickness Distribution in Hole Flanging using Incremental Sheet Metal Forming

2019 ◽  
Vol 9 (2) ◽  
pp. 666-669
Keyword(s):  
Surface Roughness ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Thickness Distribution ◽  
Research Work ◽  
Preheating Temperature ◽  
Incremental Sheet Metal Forming ◽  
Best Parameter ◽  
Hole Flanging

Incremental Sheet metal forming is a die less method of forming which offers high formability. In this research work; effect of step depth, tool rotation speed and preheating temperature on surface roughness and thinning of flange wall is investigated in hole flanging using incremental forming. The parameter optimization is carried out by Taguchi method. Grey relational analysis is carried out to obtain best parameter combination.

An Analytical Model to Reduce Spring-Back in Incremental Sheet Metal Forming (ISMF) Process

2009 ◽  
Vol 83-86 ◽  
pp. 1113-1120 ◽  
Author(s):  
Mehdi Vahdati ◽  
Mohammad Sedighi ◽  
Hossein Khoshkish
Keyword(s):  
Sheet Metal ◽  
Process Parameters ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Sheet Thickness ◽  
Spring Back ◽  
Step Size ◽  
Influence Of Process Parameters ◽  
Incremental Sheet Metal Forming ◽  
Tool Diameter

In this paper, spring-back and its effect on geometrical and dimensional accuracy of incremental sheet metal forming (ISMF) process has been studied. The influence of process parameters such as: vertical step size, sheet thickness, tool diameter, feed rate and spindle speed have been investigated. A series of experimental tests have been carried out for a straight groove bead-shape part made of aluminum sheets. A reliable statistical analysis has been carried out to extract the importance of each parameter. The obtained model permits to select appropriate process parameters to reduce spring-back effectively.

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