scholarly journals UFG-Microstructures by Linear Flow Splitting

2008 ◽  
Vol 584-586 ◽  
pp. 68-73 ◽  
Author(s):  
Clemens Müller ◽  
Tilman Bohn ◽  
Enrico Bruder ◽  
Peter Groche
Keyword(s):  
Mechanical Properties ◽  
Sheet Metal ◽  
Process Zone ◽  
Roll Forming ◽  
Microstructural Development ◽  
Cold Forming ◽  
Linear Flow ◽  
Flow Splitting ◽  
Processing Zone ◽  
Splitting Process

Linear flow splitting is a new continuous cold forming process where the edge of a sheet metal is formed into two flanges by splitting and supporting rolls. Thus the production of bifurcated profiles from sheet metal without lamination of material becomes feasible. The production of such structures takes place incrementally in a modified roll forming machine. Experimental investigateons on a HSLA steel show, that even at a surface increase of the sheet edge of about 1800% no cracks were nucleated in the profiles. EBSD measurements in the splitting centre reveal that similar to other SPD processes UFG microstructures develop in the processing zone. Thus a steady state is reached in the processing zone where increasing strain has no more (or little) influence on the materials properties i.e. its deformability, as it is typical for SPD-processes. The formation of UFG microstructures is considered to be a mandatory condition for the linear flow splitting process, as it improves the formability of the material to the extremely high level required for this process. The mechanical properties of profiles produced by linear flow splitting are characterised by large gradients, depending on the local deformation and the resulting microstructure. Very high hardness is measured at the former processing zone, i.e. the splitting centre and the flange surface, where severe plastic deformation takes place and UFG microstructures are present. In direction to lower deformation i.e. with increasing distance to the splitting ground or flange surface the hardness decreases close to the level of the undeformed material. In the present paper the linear flow splitting process is introduced and the microstructural development in the process zone is discussed on the base of EBSD measurements on profiles of the steel ZStE 500. The repartition of mechanical properties in a bifurcated profile is demonstrated by detailed hardness measurements.

scholarly journals Properties of UFG HSLA Steel Profiles Produced by Linear Flow Splitting

2008 ◽  
Vol 584-586 ◽  
pp. 661-666 ◽  
Author(s):  
Enrico Bruder ◽  
Tilman Bohn ◽  
Clemens Müller
Keyword(s):  
Mechanical Properties ◽  
Hsla Steel ◽  
Recrystallization Temperature ◽  
Forming Process ◽  
Cold Forming ◽  
Linear Flow ◽  
Metal Structures ◽  
Local Strength ◽  
Flow Splitting ◽  
Processing Zone

Linear flow splitting is a new cold forming process for the production of branched sheet metal structures. It induces severe plastic strain in the processing zone which results in the formation of an UFG microstructure and an increase in hardness and strength in the flanges. Inbuilt deformation gradients in the processing zone lead to steep gradients in the microstructure and mechanical properties. In the present paper the gradients in the UFG microstructure and the mechanical properties of a HSLA steel (ZStE 500) processed by linear flow splitting are presented, as well as a calculation of local strength from hardness measurements on the basis of the Ludwikequation. In order to investigate the thermal stability of the UFG microstructure heat treatments below the recrystallization temperature were chosen. The coarsening process and the development of the low angle to high angle grain boundary ratio in the gradient UFG microstructure were monitored by EBSD measurements. It is shown that heat treatment can lead to a grain refinement due to a strong fragmentation of elongated grains while only little coarsening in the transverse direction occurs. A smoothing of the gradients in the UFG microstructure as well as in the mechanical properties is observed.

A Model for the Representation of Surface Roughness and Form Deviation in Geometry Models

2013 ◽  
Author(s):  
Oliver Weitzmann ◽  
Reiner Anderl
Keyword(s):  
Surface Roughness ◽  
Product Development ◽  
Surface Properties ◽  
Sheet Metal ◽  
Functional Integration ◽  
Higher Order ◽  
Linear Flow ◽  
Metal Parts ◽  
Sheet Metal Parts ◽  
Flow Splitting

Functional integration and resource utilization are a challenge in today’s product development. The selective utilization of surface properties for functional integration offers potentials which aren’t exhausted until now. Surface roughness is mostly considered in manufacturing and measurement but the product properties impacted by surface roughness are determined in the product development. So it is necessary to integrate and extend the information about surface roughness in the methods and models of the product development. Therefore an approach for the representation of surface properties in product development is evolved. Based on the classification of surface deviation and profile courses, a method for building a surface profile is explored and depicted in an object-oriented representation model. One example for the functional integration and the use of technology-induced properties are sheet metal parts with higher order bifurcation in integral style. A new massive forming technology called linear flow splitting enables the manufacturing of sheet metal parts with higher order bifurcation in integral style. Within this manufacturing process, the material properties change heavily. Considering these changes in the product development, the representation model is needed to ensure the functionality. The model is used for generation a typical surface resulting from a linear flow splitting process.

New Forming Processes for Sheet Metal with Large Plastic Deformation

2007 ◽  
Vol 344 ◽  
pp. 251-258 ◽  
Author(s):  
Peter Groche ◽  
Jens Ringler ◽  
Dragoslav Vucic
Keyword(s):  
Sheet Metal ◽  
Cross Sections ◽  
Lightweight Design ◽  
High Surface ◽  
Surface Hardness ◽  
Band Edge ◽  
Experimental Investigations ◽  
Large Strains ◽  
Linear Flow ◽  
Flow Splitting

Due to the high effort involved, bifurcated constructions in mass market products made from sheet metal remained largely unused. Extruded profiles with cross-sections containing bifurcations show the possibility to increase the stiffness and allow modern lightweight design using load optimized structures as well as in box strap, sandwich and stringer constructions or different profiles. The two new forming processes linear flow splitting and linear bend splitting developed at the PtU enable the production of bifurcated profiles in integral style made of sheet metal without joining, lamination of material or heating of the semi-finished product. These forming processes use obtuse angled splitting rolls and supporting rolls to transform the sheet metal at ambient temperature. Whereas the linear flow splitting process increase the surface of the band edge and forms the band into two flanges. At linear bend splitting a bended sheet metal as semi finished product is used. Thereby bifurcations at nearly any place of a sheet metal can be produced. Both processes induce high hydrostatic compressive stresses in the local forming zone during the process which leads to an increased formability of the material and thereby to the realization of large strains. Parts produced are characterized by increased stiffness, high surface hardness and low surface roughness. Experimental investigations have shown an increasing of the band edge surface at maximum splitting depth up to 1800%. By a following forming process new multi-chambered structures and integral stringer construction can be realized with thin walled cross-sections from steel of higher strength.

scholarly journals Benefits of stress superposition in combined bending-linear flow splitting process

2016 ◽  
Vol 11 (1) ◽  
pp. 19-29 ◽  
Author(s):  
P. Groche ◽  
C. Taplick ◽  
M. Özel ◽  
P. Mahajan ◽  
S. Stahl
Keyword(s):  
Linear Flow ◽  
Flow Splitting ◽  
Stress Superposition ◽  
Splitting Process

Automated Import of XML-Files Containing Optimized Geometric Data to 3D-CAD-Models of Non-Linear Integral Bifurcated Sheet Metal Parts

2015 ◽  
Author(s):  
Thiago Weber Martins ◽  
Katharina Albrecht ◽  
Reiner Anderl
Keyword(s):  
Product Development ◽  
Sheet Metal ◽  
Data Model ◽  
Product Development Process ◽  
Linear Flow ◽  
Sheet Metal Parts ◽  
3D Cad ◽  
Geometric Data ◽  
Cad Models ◽  
Flow Splitting

The Collaborative Research Centre 666 has the focus on researching fundamental new methods for the development of optimized products and production processes for integral bifurcated sheet metal parts. Technological innovations have been achieved with respect to new production processes such as linear flow splitting and linear bend splitting as well as to produce products with flexible profiles. The use of state of art product development methodologies can be applied but these are not optimized to deal with the high complexity of the requirements and properties of integral bifurcated sheet metal products. In order to deal with that complexity a new approach of a product development methodology, the algorithm based product development process, has been established. Within the scope of the algorithm based product development methodology a topology optimization, based on mathematical algorithms using product requirements information, is already applied in the conceptual steps of product development process. By using this methodological approach an optimized concept of bifurcated sheet metal can be determined. The results are stored as optimized geometric data in XML-format files. 3D-CAD-Models are generated based on these data. However the import of these data into 3D-CAD-Systems are not fully automated. The developed data model, from earlier works for linear flow splitting and linear bend splitting, does not take into account the variability of the profiles in the third-dimension. In addition the topology optimization does not provide production-orientated design requirements and therefore it does not take into account the production process limits (of linear flow splitting and linear bend splitting). Hence 3D-CAD-Models resulting from the optimized geometric data need to be adapted manually. Therefore new advanced approaches in terms of virtual product development tools need to be explored. This paper describes the development of an interface within the CAD-System Siemens NX which supports the automatic import of XML-files containing the optimized geometric data of non-linear integral bifurcated sheet metal in 3D-CAD-Models. The existing data model is extended considering the requirements of the developed interface in order to represent nonlinear bifurcated profiles. An approach of the interface using the described data model and the NX Open API is introduced and explained.

The Structure and Mechanical Properties of Aluminum Cellular Metal With Periodic Cubic Cells

2016 ◽  
Author(s):  
Xiaobing Dang ◽  
Ruxu Du ◽  
Kai He ◽  
Qiyang Zuo
Keyword(s):  
Mechanical Properties ◽  
Relative Density ◽  
Sheet Metal ◽  
Light Weight ◽  
Practical Applications ◽  
Sheet Metal Stamping ◽  
High Stiffness ◽  
The Past ◽  
Cellular Metal ◽  
Metal Stamping

As a light-weight material with high stiffness and strength, cellular metal has attracted a lot of attentions in the past two decades. In this paper, the structure and mechanical properties of aluminum cellular metal with periodic cubic cells are studied. The aluminum cellular metal is fabricated by sheet metal stamping and simple adhesion. Two sizes of specimens with cell sizes of 3mm and 5mm are fabricated. Their relative density and mechanical properties are tested by means of experiments. The results show that the cubic-cell cellular metal has high and predictable strength and hence, can be used for many practical applications.

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