Peter Groche's research while affiliated with Technische Universität Darmstadt and other places

Publications (402)

Article
Wear is one of the decisive factors for the economic efficiency of sheet metal forming processes. Thereby, progressive wear phenome lead on the one hand to a poor workpiece quality and on the other hand to tool failure resulting in high machine downtimes. This trend is intensified by processing high-strength materials and the reduction of lubricant...
Article
Hybridstrukturen aus Metallen und Faser-Kunststoff-Verbunden (FKV) bieten vielseitige Vorteile, da in ihnen die Eigenschaften zweier grundlegend verschiedener Werkstoffarten vereint sind. Durch ein gezieltes Ausnutzen des unterschiedlichen Materialverhaltens während der Umformung werden Metallblechstrukturen und FKV-Schlaufen nicht nur miteinander...
Article
There is extensive evidence in the literature that plastic deformation of metals is associated with an increase in Acoustic Emission (AE) activity. Thus, AE measurement techniques have the potential to monitor a forming process in real time and provide a signal for feedback control, to exploit optimum formability. In this work, custom-made AE senso...
Article
The wear resistance diagram (WRD) is a useful tool for quantitatively estimating the life span of a tribological system in sheet metal forming at different load levels. However, the WRD derived from the authors’ previous research consists merely of scattered points, which make it difficult to reliably estimate the life span and its uncertainties at...
Article
High-strength aluminum alloys, such as the AA7075 alloy, offer great potential for lightweight construction thanks to their high specific strength. However, high strength and low ductility are a challenge for processing these materials. In our study, three different process routes (T6, W-Temper, O) for roll forming of a hat profile are investigated...
Chapter
Blanking is one of the most important processes for manufacturing sheet metal parts with complex geometry in high precision. Abrasive wear of the cutting edge and adhesive wear of the lateral surface of the punch as a result of the high sliding speed and local pressure have a decisive influence on the tool life. In addition to the forces in the cut...
Article
Full-text available
Following the industrial change from mass production towards serial customization flexible technologies are becoming increasingly important. Therefore, the novel forming process “flexible roller beading” (FRB) is developed, which enables the continuous production of sheet metal profiles with customizable variable cross-sectional height and exploits...
Chapter
Energy efficiencyEnergy efficiency is a primary objective in industrial processes nowadays. Roll formingRoll forming represents a well-established and widespread technology in mass production. In this process, a sheet metal is conveyed by frictional contact with the roll forming tools. The varying roll diameter along the sheet contact line entails...
Article
Pre-stressing enables slender and high-strength structures in civil engineering. Previous studies have shown that it also offers a high potential for lightweight design of load-bearing sheet metal structures. Here, it is not only possible to join the sheet metal structures with the necessary tendons during a forming process, but also to pre-stress...
Article
Nanostructured titanium plays an important role in biomedical applications, especially in dentistry, as the nanostructured surface promotes bone cell growth and simultaneously prevents bacterial colonization. Nanostructured microstructures can be obtained through Severe Plastic Deformation processes. In this paper, thermomechanical processing via E...
Article
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In numerical simulations of cold forging processes, the heat transfer coefficient has a significant influence on the resulting temperature fields. However, the values determined so far for steel materials are not in the load range of cold forging processes. In this paper, a test stand for the determination of the interfacial heat transfer coefficie...
Article
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CoFe lamination stacks used for high-performance electric motors can be manufactured economically in high volumes by interlocking. In order to ensure sufficient joint strength with minimized sheet thickness, a comprehensive knowledge of the influences of various process parameters, such as embossing depth, clearance and counter punch force, is esse...
Article
The high-strength aluminium alloys EN AW-6082 and -7075 are characterized by low density and high strength but also limited cold formability and pronounced springback behaviour in the ultra-high-strength T6 state. In order to exploit their lightweight design potential, temperature-supported process routes such as warm or hot forming are applied. Al...
Article
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Robustness of numerical models paves the way for efficient compensation of perturbations resulting in deviations from the nominal conditions. This is critical if the numerical simulations will be used to determine closed-loop process control adjustments to assure the final part quality. This work details the procedure to establish and validate nume...
Article
Process specific actuators and sensors embedded in the tooling can enable closed-loop control of product properties in manufacturing processes to achieve desired final component characteristics. Alternatively, actuation conducted by the machine tool used and sensors positioned within the machine, i.e., outside of the tool, could increase robustness...
Article
The potential of data for inline detection of changes in the physical state of sheet metal forming processes has been proven over the last decade. However, with production rates exceeding 300 parts per minute the time available for a workpiece-related processing of sensor data is reduced. Therefore, the analysis of large data sets is outsourced to...
Article
Due to their enhanced mechanical and magnetic properties, composite wire bundles play a central role in many industrial areas. For the production of these parts, continuous metal forming processes with stationary conditions are economically advantageous and enable large-scale production. However, the different mechanical properties of the materials...
Article
Although data characterized by sensorial acquired time series combined with ma-chine learning algorithms are the fundamental for mastering the challenges of modern production systems, their potential is rarely exploited in real-world manufacturing ap-plications. The literature presents systematic process models to generate knowledge from data sets,...
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
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Friction is one of the variables that have a far-reaching influence on forming processes. In the past, less attention was paid to static friction than to sliding friction in forming processes. In this paper, a test stand for the determination of static friction under load in metal forming is presented. The results are discussed using the example of...
Article
Full-text available
In engineering applications almost all processes are described with the help of models. Especially forming machines heavily rely on mathematical models for control and condition monitoring. Inaccuracies during the modeling, manufacturing and assembly of these machines induce model uncertainty which impairs the controller’s performance. In this pape...
Article
Full-text available
The productivity of a deep drawing process strongly relies on its robustness as well as the experience of the machine operator. Steadily increasing requirements regarding weight, design and efficiency lead to a production operating increasingly closer to the process limits, making it more challenging to ensure a high robustness of the process. Mini...
Article
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The present study provides an overview of previous studies on the welding of the AA7075-T6 aluminum alloy, followed by an investigation of the influence of short-time solution annealing on the mechanical properties of the weld. Conventional laser welding of Al-Zn-alloys leads to a low weld strength, which makes a post weld heat treatment (PWHT) fav...
Article
Rolling operations with flat dies allow the highly efficient production of cylindrical parts in large quantities. [1] Latest trends towards shorter lifecycle times and increasing product complexity [2] strengthen the need for an efficient design process of flat die rolling operations. Finite element modelling plays a major role in establishing an e...
Article
For conventional sheet metal forming at room temperature, numerous tribometers were developed in the 20th century. At the present state of the art, unsolved issues for tribometry remain for temperature-supported forming processes of high strength aluminum (e.g. EN AW-7075), in which the sheet is heated to temperatures between 200 and 480 °C. The tr...
Article
Full-text available
Blanking processes belong to the most widely used manufacturing techniques due to their economic efficiency. Their economic viability depends to a large extent on the resulting product quality and the associated customer satisfaction as well as on possible downtimes. In particular, the occurrence of increased tool wear reduces the product quality a...
Article
Full-text available
In recent years, the trend to extend the functionality of passive metallic structures in mechanical engineering through sensor integration has emerged. This trend is driven by the growing demand for monitoring and/or control approaches. Current state of the art sensory structures and machine elements are successfully produced by integrating sensors...
Article
Over the past 15 years, numerous tribological systems for warm and hot aluminium sheet metal forming have been investigated by various researchers. Two previously disregarded aspects will be examined in this paper with an enhanced strip drawing test: the temperature influence on friction and wear performance in an extensive comparison of different...
Article
Full-text available
In consequence of high cost pressure and the progressive globalization of markets, blanking, which represents the most economical process in the value chain of manufacturing companies, is particularly dependent on reducing machine downtimes and increasing the degree of utilization. For this purpose, it is necessary to be able to make a real-time pr...
Article
Die Wirtschaftlichkeit industrieller Stanzprozesse hängt stark von produzierten Bauteilqualitäten und Stillstandzeiten ab. Negativ werden diese von Verschleißerscheinungen an genutzten Stanzstempeln beeinflusst, weswegen datengetriebene Überwachungssysteme sowohl in industrieller Praxis als auch akademischer Forschung entwickelt werden. Insbesonder...
Article
Image-based Deep Learning (DL) applications have been increasingly applied in manufacturing processes in recent years and enable real-time decisions to be derived on the basis of raw image data. However, there are major obstacles that prevent a widespread application. The generation of extensively labeled datasets is associated with costly experime...
Article
Full-text available
Roll forming is a continuous manufacturing process designed for large batch sizes. In order to economically produce roll formed parts with smaller batch sizes, the process setup times have to be reduced. During the setup, profile defects and especially the deformation caused by the release of the process-inherent residual stresses, also known as en...
Chapter
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This chapter describes three general strategies to master uncertainty in technical systems: robustness, flexibility and resilience. It builds on the previous chapters about methods to analyse and identify uncertainty and may rely on the availability of technologies for particular systems, such as active components. Robustness aims for the design of...
Chapter
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This chapter serves as an introduction to the main topic of this book, namely to master uncertainty in technical systems. First, the difference of our approach to previous ones is highlighted. We then discuss process chains as an important type of technical systems, in which uncertainty propagates along the chain. Five different approaches to maste...
Chapter
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Uncertainty affects all phases of the product life cycle of technical systems, from design and production to their usage, even beyond the phase boundaries. Its identification, analysis and representation are discussed in the previous chapter. Based on the gained knowledge, our specific approach on mastering uncertainty can be applied. These approac...
Chapter
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Bertolt Brecht once closed a text with the words “We are disappointed to see the curtain close and all questions are left unanswered” [1]. In this book, it has become clear that uncertainty is immanent in the product life cycle of technical systems in mechanical engineering from (B) production, (C) usage, (D) reuse to (E) sourcing. The latter is th...
Chapter
Lightweight construction continues to be of outstanding importance for many industrial sectors, and often relies on ribs or stringers to stiffen flat surfaces. Stringer sheet forming provides an efficient path to produce stiffened parts avoiding the disadvantages of milling or casting these structures. However, due to the deep penetration welding p...
Chapter
Modern production chains are subject to constantly growing demands for agility, adaptability, variant diversity and robustness. These demands can push even sophisticated systems to their limits. For product validation during development, as well as for disturbance compensation, the macroscopic paraffin wax phase change actuator (PCA) is a proven to...
Article
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Due to their excellent combination of space enclosing, heat insulating and supporting function, steel sandwich panels – mostly flat – are used for roofs and walls of standard industrial buildings. Because freely formed structures generally are playing an increasing role in contemporary architecture, curved sandwich panels would offer a high potenti...
Chapter
The aim of minimizing scrap material while increasing product diversification at the same time requires more efficient solutions for production processes. Due to longitudinal strains introduced during roll forming processes, deviations in straightness occur. The lack of universally valid rules for the setting correcting equipment leads to iterative...
Conference Paper
Full-text available
For dental implant applications, titanium is the first choice because of its low elastic modulus, high strength, biocompatibility as well as excellent corrosion resistance. Typical alloys used in dental implants are Ti 6Al 4V (ELI) and commercially pure (CP) Titanium Grade 4. Compared to that of the jawbone (< 20 GPa), their Young's modulus (> 105...
Article
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Cold extruded components are characterized by residual stresses, which originate from the experienced manufacturing process. For industrial applications, reproducibility and homogeneity of the final components are key aspects for an optimized quality control. Although striving to obtain identical deformation and surface conditions, fluctuation in t...
Article
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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...
Preprint
Full-text available
Blanking processes belong to the most widely used manufacturing techniques due to their economic efficiency. Their economic viability depends to a large extent on the resulting product quality and the associated customer satisfaction as well as on possible downtimes. In particular, the occurrence of increased tool wear reduces the product quality a...
Article
Full-text available
Collision welding is a joining technology that is based on the high-speed collision and the resulting plastic deformation of at least one joining partner. The ability to form a high-strength substance-to-substance bond between joining partners of dissimilar metals allows us to design a new generation of joints. However, the occurrence of process-sp...
Article
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In this paper we present a novel, cost-effective camera-based multi-axis force/torque sensor concept for integration into metallic load-bearing structures. A two-part pattern consisting of a directly incident and mirrored light beam is projected onto the imaging sensor surface. This allows the capturing of 3D displacements, occurring due to structu...
Article
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Zusammenfassung Ausgehend von vorherigen Ergebnissen zur Prozessoptimierung fließgepresster Proben aus dem austenitischen Werkstoff 1.4404 mittels einer aktiven Prozessführung zur Verbesserung des Eigenspannungszustands, wurde das gleiche Verfahren auf den metastabilen austenitischen Werkstoff 1.4307 angewandt. Es wurden neue Erkenntnisse erwartet,...
Article
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Today’s deep drawing of car body parts is operated increasingly closer to the process limits, making it more challenging to ensure a high robustness of the process. Disturbances like varying material properties or changing tribological conditions may negatively affect the process, leading to deteriorated product properties and a loss of productivit...
Article
Full-text available
The high-strength aluminium alloys EN AW-6082 and -7075 possess great light-weight construction potential due to their high specific strength. However, their range of applications is limited by the low cold formability and high springback in the ultra-high-strength T6 state. To extend formability, either preconditioned semi-finished products, requi...
Chapter
Full-text available
Machine elements produced in large quantities undergo several development cycles and can be adapted from generation to generation. Thus, experiences from real operation can be taken into account in further development. This is not possible for innovative investment goods such as special purpose machines, as these are usually individual items. There...
Article
In diesem Beitrag wird das KDT-EA (Knowledge Discovery in Time Series for Engineering Applications) vorgestellt, eine Verbesserung des bestehenden KDD-Prozesses, um speziell die Analyse von aufgezeichneten Zeitreihen in Produktionsprozessen zu adressieren. Es werden die Schritte von der Datenerfassung bis zur Implementierung der entwickelten Modell...
Article
The measurement of thermoelectric current is a new and effective method for inline wear detection in sheet metal forming. The measuring principle is based on the Seebeck effect, whose characteristic value, the Seebeck coefficient depends on the material composition. In the previous research of the authors, a boundary value of the thermoelectric val...
Article
Expedient residual stress distributions offer extensive opportunities for improved product properties. Metal forming process chains provide an excellent opportunity for the targeted manipulation of residual stresses. The required purposeful process design has to take into account the possible inheritance of residual stress states along the process...
Article
The relevance of the magnetic Barkhausen noise (MBN) and the non-destructive characterization of material properties in near surface layers, has increased in recent years.With the development of new signal processing techniques, the method was further developed into a powerful evaluation technique and is used in various areas of online and offline...
Article
Full-text available
In sheet metal forming, free deformation of the sheet takes place frequently without contact with forming tools. The pre-straining resulting from the free deformation leads to a surface roughening of the sheet metal. It is assumed that the roughening has an influence on friction and wear behavior of the following forming process as well as the pain...
Article
Full-text available
The presented paper provides a modelling strategy for roll forming of a high strength AA7075 aluminum tube. Roll forming allows the cost-effective production of large quantities of long profiles. Forming of high strength aluminum brings challenges like high springback and poor formability due to the low Young’s modulus, low ductility and high yield...
Article
Full-text available
With the current tendency of mass production towards customer-oriented serial production, blanking processes are facing new challenges. They require an increase in knowledge about faulty process conditions and their influence on the quality of a component as well as an instruction for a target-oriented adaptation of the process. The aim of this stu...