Bernd-Arno Behrens

Bernd-Arno Behrens
Leibniz Universität Hannover · Institute of Forming Technology and Machines

Prof. Dr.-Ing.

About

821
Publications
90,187
Reads
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4,738
Citations
Citations since 2017
353 Research Items
3217 Citations
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20172018201920202021202220230100200300400500600700
20172018201920202021202220230100200300400500600700
Additional affiliations
January 2004 - present
Leibniz Universität Hannover
Position
  • Professor

Publications

Publications (821)
Article
Full-text available
As a cost-effective hole production technique, friction drilling is widely used in industrial and automotive manufacturing. Compared with the traditional bolted connection, it enables the fastening of thin metal sheets and thin-walled tubular profiles. Friction drilling results in higher thread length and joint strength, thus better fulfilling the...
Chapter
Sheet metal forming is widely used in many industries, especially in manufacturing automotive body parts and white goods. For many years, coated kitchen utensils are being used because of their properties such as non-stick property. The most used coating is polytetrafluoroethylene (PTFE), known as Teflon. Kitchen utensils are mainly manufactured by...
Article
Aufgrund der guten Fließeigenschaften von Aluminium neigt das Material beim gratlosen Präzisionsschmieden dazu, in Werkzeugspalte zu fließen und den sogenannten Flittergrat zu erzeugen. Zur industriellen Umsetzung von gratlosen Präzisionsschmiedeprozessen sollen, in Kooperation mit einem Industriepartner, eine innovative Prognosemethode für Flitter...
Article
Full-text available
To combine the advantages of two materials, hybrid bulk metal workpieces are attractive for subsequent processes such as metal forming. However, hybrid materials rely on the initial bond strength for the effective transfer of applied loads. Thus, a non-destructive evaluation of the bonding along the production process chain is of high interest. To...
Article
Full-text available
Additive manufacturing with multi-material design offers great possibilities for lightweight and function-integrated components. A process chain was developed in which hybrid steel–steel-components with high fatigue strength were produced. For this, a material combination of stainless powder material Rockit® (0.52 wt.% C, 0.9% Si, 14% Cr, 0.4% Mo,...
Article
Full-text available
The deep-drawability of a sheet metal blank is strongly influenced by the tribological conditions prevailing in a deep-drawing process. Therefore, new methods to influence the tribology represent an important research topic. In this work, the application of a process-integrated lubrication in a deep-drawing process is investigated. Most promising g...
Article
Full-text available
The nitriding of forging tools is an industrially established standard used to increase the hardness of the tool surface layer and reduce wear. However, this modification of the tool surface layer, as well as the microstructural changes that occur during this operation due to the thermo-mechanical load, cannot be considered during wear calculations...
Article
Abstract During flat die rolling, two die plates pass each other and form the cylindrical semi-finished product enclosed within. Non-circular rolling examines the rolling of multiple, locally nonround geometries such as eccentrics. With the aid of statistical experimental design, a simulative parameter investigation has been carried out, main influ...
Article
Full-text available
Internal die cooling during forging can reduce thermal loads, counteracting surface softening, plastic deformation and abrasive die wear. Additive manufacturing has great potential for producing complex geometries of the internal cooling channels. In this study, hybrid forging dies were developed combining conventional manufacturing processes and l...
Article
Full-text available
Multi-material bulk metal components allow for a resource efficient and functionally structured component design, with a load adaptation achieved in certain functional areas by using similar and dissimilar material combinations. One possibility for the production of hybrid bulk metal components is Tailored Forming, in which pre-joined semi-finished...
Article
Full-text available
Shear cutting is a proven process for chip-less separation of metals and used as a cost-effective production method. The process design of shear cutting is usually based on time and cost intensive experimental tests. Therefore, numerical depiction of the process offers great potential to reduce these practical tests. An important aspect hereby is t...
Article
Full-text available
High-strength steels are increasingly used in deep drawing for automotive parts due to their improved strength properties. To increase the formability and thus extend the process limits, a deep drawing process with additional force transmission has been developed. For a numerical optimisation of the considered process, an exact modelling of the fai...
Article
Full-text available
n addition to using conventional lubricants, such as oil and grease, rolling bearings can also be used with a dry lubricant. For example, the use of dry lubricant systems is necessary when the application of oils or greases is not possible (e.g., at high temperatures or in aerospace applications). The requirements of a solid lubricant are to reduce...
Article
Full-text available
Tailored forming is used to produce hybrid components in which the materials used are locally adapted to the different types of physical, chemical and tribological requirements. In this paper, a Tailored Forming process chain for the production of a hybrid shaft with a bearing seat is investigated. The process chain consists of the manufacturing st...
Article
Full-text available
Today, design and operation of manufacturing processes heavily rely on the use of models, some analytical, empirical or numerical i.e. finite element simulations. Models do reflect reality as best as their design and structure may appear, but in many cases, they are based on simplifying assumptions and abstractions. Reality in production, i.e. refl...
Article
Full-text available
The aim of the investigations described in this article is to improve the clinching of aluminum die casting. The focus is on clinching an aluminum die casting alloy by local heat treatment and hence to join them in a process-safe manner. For this purpose, a heating strategy is used to warm up the die casting alloys to reduce temporarily and reversi...
Article
Full-text available
Due to the increased integration of functions, many components have to meet high and sometimes contradictory requirements. One way to solve this problem is Tailored Forming. Here, hybrid semi-finished products are manufactured by a joining or cladding process, which are then hot-formed and finished. For the design of hybrid components for a possibl...
Article
Full-text available
The Tailored Forming process chain is used to manufacture hybrid components and consists of a joining process or Additive Manufacturing for various materials (e.g. deposition welding), subsequent hot forming, machining and heat treatment. In this way, components can be produced with materials adapted to the load case. For this paper, hybrid shafts...
Article
Full-text available
Within the framework of the Collaborative Research Center 1153, we investigated novel process chains for the production of bulk components with different metals as joining partners. In the present study, the co-extrusion of coaxially reinforced hollow profiles was employed to manufacture semi-finished products for a subsequent die-forging process,...
Article
Abstract The use of acquired measurement data for the monitoring and optimization of processes is becoming more and more important in production engineering. This paper describes the setup of a data acquisition system for forming machines. In addition to the design and selection of suitable system components, the appropriate processing and reductio...
Article
Full-text available
Spark plasma sintering (SPS) or the field-assisted sintering technique (FAST) is commonly used to process powders that are difficult to consolidate, more efficiently than in the conventional powder metallurgy process route. During the process, holding time and applied holding pressure influence the product’s microstructure and subsequently its prop...
Book
This congress proceedings provides recent research on leading-edge manufacturing processes. The aim of this scientific congress is to work out diverse individual solutions of "production at the leading edge of technolgy" and transferable methodological approaches. In addition, guest speakers with different backgrounds will give the congress partici...
Article
Durch Prozessüberwachungsstrategien lassen sich verschleißbedingte Zustände von Schmiedegesenken erkennen und prognostizieren. Die Prognose des Verschleißzustands erlauben intelligente Instandhaltungsstrategien. Dadurch lassen sich Reststandmengen voll ausschöpfen, Ausschuss reduzieren und Ausfallzeiten einkalkulieren. Inhalt dieses Beitrags ist di...
Article
Im Unrundwalzen wird die Machbarkeit untersucht, mehrere zueinander versetzte, lokal unrunde Formelemente in ein zylindrisches Halbzeug zu walzen. Ein Teilgebiet der Untersuchungen ist das Walzen von zwei elliptischen Abschnitten. Aus drei unterschiedlichen Berechnungskonzepten für die Bestimmung der Werkzeuggravur wurde einer für eine simulative P...
Article
Im Automobil- und Maschinenbau werden massivumgeformte Bauteile in vielen Anwendungen eingesetzt. Die Gesenke für die Bauteile erfahren während der Umformung aufgrund von hohen Umformkräften und Temperaturen einen hohen Verschleiß. Um einen wirtschaftlichen Produktionsbetrieb zu ermöglichen, wurden Methoden zur Verminderung des Verschleißes bei der...
Article
The impact extrusion of axially arranged steel-aluminium billets was studied in this research. Two different bi-material billet concepts were considered: discrete and prejoined billets. Discrete billets were formed in order to achieve a joint through plastic deformation. Prejoined billets were created by friction welding beforehand and their behavi...
Article
Full-text available
Friction drilling is a widely used process to produce bushings in sheet materials, which are processed further by thread forming to create a connection port. Previous studies focused on the process parameters and did not pay detailed attention to the material flow of the bushing. In order to describe the material behaviour during a friction drillin...
Article
Full-text available
Warm forged components have better surface properties and higher dimensional accuracy than hot forged components. Diamond-like-carbon (DLC) coatings can be used as wear protection coatings, which are anti-adhesive and extremely hard (up to 3500 HV), to increase tool service life. In the first funding period of the research project at the IPH – Inst...
Article
Full-text available
The process of press hardening is gaining importance in view of the increasing demand for weight reduction combined with higher crash safety in cars. An alternative to the established manganese-boron steel 22MnB5 is hot-formed martensitic chromium steels such as AISI 420C. Strengths of 1850 MPa and elongations of 12% are possible, exceeding those o...
Article
Full-text available
The optimal design of the tools in bulk metal forming is a crucial task in the early design phase and greatly affects the final accuracy of the parts. The process of tool geometry assessment is resource- and time-consuming, as it consists of experience-based procedures. In this paper, a compensation method is developed with the aim to reduce geomet...
Article
Full-text available
Zusammenfassung Ziel dieser Arbeit ist die Einstellung eines vorteilhaften Druckeigenspannungsprofils in warmumgeformten Bauteilen durch intelligente Prozessführung mit angepasster Abkühlung aus der Schmiedewärme. Die Machbarkeit und das Potenzial werden an einem Warmumformprozess, bei dem zylindrische Proben mit exzentrischer Bohrung bei 1000 °C u...
Chapter
In the hot-stamping process, a sheet blank, usually a manganese boron steel like 22MnB5, is heated up to the austenitising temperature in a roller hearth furnace and then formed in a cooled forming tool. This leads to tensile strengths of about 1500 MPa in the formed parts. The components produced in this process are used in particular in the autom...
Chapter
This paper describes the investigation of a compression molding process for the production of a battery housing structure made of glass mat reinforced thermoplastic (GMT) for electric vehicles. The battery housing structure was scaled to a demonstrator geometry in the form of a battery shell. To enable variant-flexible manufacturing, a modular form...
Chapter
The most frequently used process for shaping metal powders is the two-sided pressing in dies. The properties of the green compact resulting from this pressing process, such as green density and strength, are decisive for the final density of the sintered component and thus for mechanical properties like tensile and fatigue strength. Green-compact p...
Chapter
For electronic components, micro parts are produced in large quantities. Hence, in modern production lines constantly increasing stroke rates are targeted to reach high productivity. The used foil material is usually fed by roll feeding systems, which limit the feeding rate and potentially cause damage to the foil’s surface. A promising alternative...
Chapter
Tailored Forming provides an innovative process chain for manufacturing hybrid components. This study focuses on a process design of a hybrid bearing bushing consisting of aluminium alloy EN-AW-6082 and Titan-Grade-2 or -5 using numerical simulation. The manufacturing process used was a closed die forging process with pre-joined hybrid semi-finishe...
Chapter
Full-text available
The focus of this study is to improve the clinching ability of an aluminum die casting alloy with a sheet metal by local annealing in order to clinch them in a process-safe manner. For this purpose, the influence of three different heating strategies (heating plate, resistance heating and inductive heating) on the generation of clinching joints are...
Article
Full-text available
The 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...
Article
Full-text available
The aim of this work is to generate an advantageous compressive residual stress distribution in the surface area of hot-formed components by intelligent process control with tailored cooling. Adapted cooling is achieved by partial or temporal instationary exposure of the specimens to a water–air spray. In this way, macroscopic effects such as local...
Article
Die manuelle Handhabung von Schmiedeteilen ist für Schmiedemitarbeiter körperlich stark belastend. Diese körperlichen Belastungen spiegeln sich in Schädigungen des Hand-Arm-Systems und Rückens wider und führen zum Ausfall der Schmiedemitarbeiter. Um die Gesundheit der Schmiedemitarbeiter zu schonen, ist das Ziel die Grundbelastung durch das Eigenge...
Article
Das Flachbackenwalzen ist der Massivumformung zuzuordnen, in welchem zwei mit Gravuren versehene Werkzeugplatten aneinander vorbeilaufen und dabei ein zylindrisches Halbzeug umformen. Mithilfe des Unrundwalzens als Vorformverfahren soll es ermöglicht werden, lokal unrunde Abschnitte, beispielsweise Ellipsen oder Exzenter in ein Halbzeug zu formen....
Article
Full-text available
Overmoulding of thermoplastic composites combines the steps of thermoforming and injection moulding in an integrated manufacturing process. The combination of continuous fibre-reinforced thermoplastics with overmoulded polymer enables the manufacturing of highly functionally integrated structures with excellent mechanical properties. When performed...
Article
Full-text available
The heat-treatable steel 22MnB5 is used in hot stamping processes to produce high-strength body-in-white components. In this process, sheet blanks are conventionally heated in roller hearth furnaces and then hot-stamped, whereby strengths of 1,500 MPa can be achieved. Disadvantages of this process are the low plastic deformation of the material in...
Article
Full-text available
As a result of global economic and environmental change, the demand for innovative, environmentally-friendly technologies is increasing. Employing solid lubricants in rolling contacts can reduce the use of environmentally harmful greases and oils. The aim of the current research was the development of a solid lubricant system with regenerative prop...
Conference Paper
Full-text available
The increasing demand for resource-efficient production methods is driving the development of new technologies. Sheet bulk metal forming (SBMF) offers the possibility to combine sheet metal and bulk forming operations. This allows the production of complex functional components with secondary forming elements from sheet metal. Compared to other pro...
Article
Bulk metal components are often used in areas which are subjected to very high loads. For most technical components, a distinction between structural and functional areas can be made. These areas usually have very different loading profiles, sometimes with contradictory requirements. Nevertheless, nowadays almost only monomaterials are used for the...
Article
The acquisition and evaluation of process data in production engineering holds great potential. This allows detecting faulty processes at an early stage and processes to be optimized even more efficiently. However, the use of technologies for data acquisition in the manufacturing industry is far less widespread than the mentioned potential implies....
Article
Multi-material solutions represent a promising approach for the production of load-optimised parts. The combination of material-specific advantages of different materials in a single component allows the fulfilment of conflicting requirements e.g. high performance and low weight. Fabrication of hybrid components is challenging due to the dissimilar...
Article
Multi-material solutions offer benefits, as they, in contrary to conventional monolithic parts, are customised hybrid components with properties that optimally fit the application locally. Adapted components offer the possibility to use high strength material in areas where external loads require it and substitute them by lightweight material in th...
Article
Full-text available
Tools are of strategic importance for industrial manufacturing processes. Their behaviour has a great influence on the productivity of the process and the quality of the product. A material saving and efficient technique for processing metallic workpieces is cold forging. One major challenge of this production method is the handling of high contact...
Article
Due to high thermo-mechanical loads, tools used in hot forming operations need a high resistance to different damage phenomena, such as deformation, cracking and abrasion. They are exposed to cyclic thermo-mechanical stress conditions, which leads to tool failure and subsequent tool replacement during cost-intensive production interruptions. To inc...
Article
Full-text available
Residual stresses resulting from hot-forming processes represent an important aspect of a component’s performance and service life. Considering the whole process chain of hot forming, the integrated heat treatment provided by a defined temperature profile during cooling offers a great potential for the targeted adjustment of the desired residual st...
Article
Full-text available
Fringe projection profilometry in combination with other optical measuring technologies has established itself over the last decades as an essential complement to conventional, tactile measuring devices. The non-contact, holistic reconstruction of complex geometries within fractions of a second in conjunction with the lightweight and transportable...
Article
Full-text available
The demand for lightweight construction is constantly increasing. One approach to meet this challenge is the development of hybrid components made of dissimilar materials. The use of the hybrid construction method for bulk components has a high potential for weight reduction and increased functionality. However, forming workpieces consisting of dis...
Poster
Full-text available
Knowledge about the tribological interactions occurring between workpiece/chip and the cutting insert in lubricated turning processes is of great interest to model and to optimize the machining process. Taking the chip-tool contact as an example, the temperature at the interface can be easily over 400°C, which is usually much higher than that in lu...
Article
Full-text available
The production of hybrid components involves a long process chain, which leads to high investment costs even before machining. To increase process safety and process quality during finishing, it is necessary to provide information about the semi-finished parts geometry for the machining process and to identify defect components at an early stage. T...