scholarly journals Strategies for residual stress adjustment in bulk metal forming

2021 ◽  
Author(s):  
A. Franceschi ◽  
J. Stahl ◽  
C. Kock ◽  
R. Selbmann ◽  
S. Ortmann-Ishkina ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Metal Forming ◽  
Fatigue Behaviour ◽  
Stress Generation ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Bulk Forming ◽  
Process Modification

AbstractThe family of bulk forming technologies comprises processes characterised by a complex three-dimensional stress and strain state. Besides shape and material properties, also residual stresses are modified during a bulk metal forming process. The state of residual stresses affects important properties, like fatigue behaviour and corrosion resistance. An adjustment of the residual stresses is possible through subsequent process steps such as heat treatments or mechanical surface modification technologies, like shot peening and deep rolling. However, these additional manufacturing steps involve supplementary costs, longer manufacturing times and harmful effects on the product quality. Therefore, an optimized strategy consists in a targeted introduction of residual stresses during the forming processes. To enable this approach, a fundamental understanding of the underlying mechanisms of residual stress generation in dependence of the forming parameters is necessary. The current state of the art is reviewed in this paper. Strategies for the manipulation of the residual stresses in different bulk forming processes are classified according to the underlying principles of process modification.

Influence of Superimposing of Oscillation on Sheet-Bulk Metal Forming

2013 ◽  
Vol 554-557 ◽  
pp. 1484-1489 ◽  
Author(s):  
Bernd Arno Behrens ◽  
Sven Hübner ◽  
Milan Vucetic
Keyword(s):  
Metal Forming ◽  
Dimensional Change ◽  
Extrusion Process ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Bulk Forming ◽  
State Of Stress ◽  
Metal Forming Process ◽  
Excitation Frequencies

Due to novel processes like sheet-bulk metal forming, the requirements for sheet metal forming are increased. Sheet-bulk metal forming is a new interconnected process in which the part itself is manufactured by deep drawing and the gearing will be produced with bulk forming in a combined process at room temperature. This process is characterized by a triaxial state of stress and a triaxial dimensional change with true strains up to  = 1-2 by using sheet blanks. Within the use of superimposing of oscillation on a sheet-bulk metal forming process the required forming force can be reduced and the accuracy of dimension of the part can be improved. Within this paper the influence of the superimposing of oscillation on the sheet bulk metal forming will be shown on combined ironing and external extrusion process. For the superimposing of oscillation different excitation frequencies will be analysed. Furthermore the die clearance will be varied to increase the requirements on the process. Finally the influence of the different excitation frequencies and the different die clearances will be summarized in cause and effect relationship diagram.

An Experimental and Numerical Assessment of Sheet-Bulk Formability of Mild Steel DC04

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Celal Soyarslan ◽  
Dennis P. F. Fassmann ◽  
Björn Plugge ◽  
Kerim Isik ◽  
Lukas Kwiatkowski ◽  
...  
Keyword(s):  
Metal Forming ◽  
Shear Fracture ◽  
Numerical Study ◽  
Design Procedure ◽  
Emission Spectrometry ◽  
Forming Limit ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Bulk Forming

This paper presents investigations on development of a new way of teeth-forming, which is related to sheet-bulk metal forming, with application of incremental bulk forming process to sheets. For this purpose, a combined experimental-numerical study on damage assessment in sheet-bulk forming of DC04 is presented. Using scanning electron microscope (SEM) and glow discharge optical emission spectrometry (GDOS), a combined quantitative/qualitative metallurgical survey is carried out on undeformed specimens to illuminate microstructural aspects in the context of nonmetallic inclusion content, distribution and size which act as prime failure factors. These surveys are extended to monitor ductile damage accumulation with cavitation at different stages of the incremental sheet indentation process over certain sections. An anticipated failure mode is captured where formability is limited by severe macro-cracking preceded by localization with void sheeting. To this end, using a developed VUMAT subroutine for the micromechanically based Gurson damage model which is recently enhanced for shear fracture, the processes are simulated in ABAQUS/Explicit and comparisons with experiments are provided. The results support the requirement of integrating powerful coupled accumulative damage models in the virtual process design procedure for sheet-bulk metal forming. This requirement also arises from distinct features of these class of processes from conventional sheet metal forming processes which preclude use of forming limit curves.

Numerical and Experimental Investigations of Multistage Sheet-Bulk Metal Forming Process with Compound Press Tools

2015 ◽  
Vol 651-653 ◽  
pp. 1153-1158 ◽  
Author(s):  
Bernd Arno Behrens ◽  
Anas Bouguecha ◽  
Milan Vucetic ◽  
Sven Hübner ◽  
Daniel Rosenbusch ◽  
...  
Keyword(s):  
Metal Forming ◽  
Solid Metal ◽  
Experimental Investigations ◽  
Metal Component ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Process Sequence ◽  
Metal Forming Process ◽  
Flange Forming

Sheet-bulk metal forming is a manufacturing technology, which allows to produce a solid metal component out of a flat sheet. This paper focuses on numerical and experimental investigations of a new multistage forming process with compound press tools. The complete process sequence for the production of this solid metal component consists of three forming stages, which include a total of six production techniques. The first forming stage includes deep drawing, simultaneous cutting and following wall upsetting. In the second forming stage, flange forming combined with cup bottom ironing takes place. In the last stage of the process sequence, the component is sized. To investigate and to improve process parameters such as plastic strain distribution, resulting dimensions and process forces, FEA is performed. Based on these results the developed process is designed.

scholarly journals Material flow control in sheet-bulk metal forming processes using blasted tool surfaces

2018 ◽  
Vol 190 ◽  
pp. 13003 ◽  
Author(s):  
Marion Merklein ◽  
Maria Löffler ◽  
Daniel Gröbel ◽  
Johannes Henneberg
Keyword(s):  
Metal Forming ◽  
Material Flow ◽  
Simultaneous Occurrence ◽  
Tribological Behaviour ◽  
Forming Process ◽  
Functional Elements ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Main Challenge ◽  
Functional Components

Highly-integrated and closely-tolerated functional components can be produced by sheet-bulk metal forming which is the application of bulk forming operations on sheet metals. These processes are characterized by a successive and/or simultaneous occurrence of different load conditions such as stress and strain states which reduce the geometrical accuracy of the functional elements. Thus, one main challenge within sheet-bulk metal forming is the identification of methods to control the material flow and thus to improve the product quality. One suitable approach is to control the material flow by local modifications of the tribological conditions. Within this study requirements regarding the needed adaption of the tribological conditions for a specific sheet-bulk metal forming process were defined by numerical investigations. The results reveal that a local increase of the friction leads to an improved die filling of the functional elements. Based on these results abrasive blasting as a method to modify the tool surface and thus influencing the tribological behaviour was investigated. For the determination of the tribological mechanism of blasted tool surfaces, the influence of different blasting media as well as blasting pressures on the surface integrity and the friction were determined. The correlations between surface properties and friction conditions were used to derive the mechanisms of blasted tool surfaces.

Material Characterization for Sheet-Bulk Metal Forming

2012 ◽  
Vol 504-506 ◽  
pp. 1029-1034 ◽  
Author(s):  
Bernd Arno Behrens ◽  
Kathrin Voges-Schwieger ◽  
Anas Bouguecha ◽  
Jens Mielke ◽  
Milan Vucetic
Keyword(s):  
Metal Forming ◽  
Material Characterization ◽  
Cyclic Load ◽  
Material Behavior ◽  
Forming Force ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Metal Forming Process

Sheet-bulk metal forming is a novel manufacturing technology, which unites the advantages and design solutions of sheet metal and bulk metal forming. To challenge the high forming force the process is superimposed with an oscillation in the main flow of the process. The paper focuses on the characterization of the material behavior under cyclic load and the effects for the sheet bulk metal forming process.

Improved Sheet Bulk Metal Forming Processes by Local Adjustment of Tribological Properties

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
H. Hetzner ◽  
J. Koch ◽  
S. Tremmel ◽  
S. Wartzack ◽  
M. Merklein
Keyword(s):  
Contact Pressure ◽  
Metal Forming ◽  
Material Flow ◽  
System Analysis ◽  
Sheet Thickness ◽  
Fe Model ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Functional Features

This paper is focused on a combined deep drawing and extrusion process dedicated to the new process class of sheet bulk metal forming (SBMF). Exemplified by the forming of gearings, combined sheet and bulk forming operations are applied to sheet metal in order to form local functional features through an intended and controlled change of the sheet thickness. For investigations on the form filling and the identification of significant influencing factors on the material flow, a FE simulation model has been built. The FE model is validated by the results of manufacturing experiments using DC04 with a thickness of 2.0 mm as blank material. Due to the fact that the workpiece is in extensive contact to the tool surface and that the pressure reaches locally up to 2500 MPa, the tribological conditions are a determining factor of the process. Thus, their influence is discussed in detail in this paper. In the first instance, different frictional zones having a distinct effect on the resulting material flow are identified and their effect on improved form filling is demonstrated. Subsequently, a more comprehensive methodology is developed to define tribological zones of forming tools. For this, a system analysis of the digital mock-up of the forming process is performed. Besides friction, other relevant aspects of forming tool tribology like contact pressure, sliding velocity, and surface magnification are considered. The gathered information is employed to partition the tools into tribological zones. This is done by systematically intersecting and re-merging zones identified for each of the criterion. The so-called load-scanning test allows the investigation of the friction coefficient in dependence of the contact pressure and possible loading limits of tribological pairings. It provides an appropriate tribological model test to evaluate tribological measures like coatings, surface textures and lubricants with respect to their targeted application in particular zones. The obtained results can be employed in the layout of further forming processes to reach the desired process behavior. This can be, for example, an improved form filling, less abrasive wear and adhesive damage or lower forming forces, respectively tool load for an improved durability of the die.

Surface roughness evolution in FEA simulations of bulk metal forming process

Wear ◽  
2012 ◽  
Vol 288 ◽  
pp. 78-87 ◽  
Author(s):  
J. Stahlmann ◽  
E.R. Nicodemus ◽  
S.C. Sharma ◽  
P. Groche
Keyword(s):  
Surface Roughness ◽  
Metal Forming ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Metal Forming Process ◽  
Surface Roughness Evolution

scholarly journals Metrological solutions for an adapted inspection of parts and tools of a sheet-bulk metal forming process

2015 ◽  
Vol 10 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Steffen Matthias ◽  
Andreas Loderer ◽  
Sergej Koch ◽  
Michael Gröne ◽  
Markus Kästner ◽  
...  
Keyword(s):  
Metal Forming ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Metal Forming Process

NUMERICAL SIMULATION OF BULK METAL FORMING BY MESHLESS METHOD

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1615-1620 ◽  
Author(s):  
HONGSHENG LIU ◽  
ZHONGWEN XING
Keyword(s):  
Finite Element ◽  
Metal Forming ◽  
Meshless Method ◽  
Reproducing Kernel ◽  
Shape Function ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Structural Applications ◽  
Forming Analysis

Conventional finite element (FE) analysis of bulk metal forming processes often breaks down due to severe mesh distortion. In recent years, meshless methods have been considerably developed for structural applications. The main feature of these methods is that the problem domain is represented by a set of nodes, and a finite element mesh is unnecessary. This new generation of computational methods can avoid time-consuming meshing and remeshing. A meshless method based on reproducing kernel particle method (RKPM) is applied to bulk metal forming analysis. The displacement shape functions are developed from a reproducing kernel (RK) approximation that satisfies consistency conditions. The shape function is modified to impose essential boundary conditions accurately and expediently. A material kernel function that deforms with the material is introduced to assure the stability of the RKPM shape function during large deformations. A program based on RKPM is developed to simulate two examples of bulk metal forming process such as ring compression and cold upsetting, and numerical results demonstrate the performance of the meshless method in bulk metal forming analysis.

Sheet-Bulk Metal Forming of Preformed Sheet Metal Parts

2011 ◽  
Vol 473 ◽  
pp. 83-90 ◽  
Author(s):  
Thomas Schneider ◽  
Marion Merklein
Keyword(s):  
Sheet Metal ◽  
Deep Drawing ◽  
Metal Forming ◽  
Sheet Plane ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Sheet Metal Parts ◽  
Bulk Forming ◽  
Process Factors ◽  
Functional Components

Due to ecological and economic challenges there is a rising demand on closely-tolerated complex functional components. Regarding short process chains and improved mechanical properties conventional forming processes are often limited. A promising approach to meet these requirements can be seen in the combination of traditional sheet and bulk metal forming processes, to form sheet metals out of the sheet plane with typical bulk forming operations. The challenge of applying conventional bulk forming operations on sheet metal is the interaction between regions of high and low deformation, which is largely unknown in literature. To analyze this topic fundamentally, a process combination of deep drawing and upsetting is developed for manufacturing tooth-like elements at pre-drawn cups. To fully understand material flow out of the sheet plane into the tooth cavity and to identify and qualify process factors depending on the functional elements´ geometry and friction, a single upsetting stage forming a simplified model of the blank is virtually analyzed with finite-element simulation. By inhibiting the forming history of the pre-drawn blank, the upsetting process can be investigated without interactions with a previous deep drawing operation.

Sign in / Sign up

Export Citation Format

Share Document