Observations on the stability of the residual stresses after cold forming and unidirectional loading

Franceschi, Alessandro; Kaffenberger, Matthias; Schork, Benjamin; Hoche, Holger; Oechsner, Matthias; Groche, Peter

doi:10.1007/s11740-018-00871-2

Cited by 7 publications

(7 citation statements)

References 16 publications

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“…Stress relaxation of large-size components is quite troublesome, mainly because of decrease in production efficiency and energy losses. Often, during the relaxation process, the objects are destroyed, which is also associated with additional costs [7,15,18,31,32]. However, it should be noted that deformations of thin-walled elements also arise from other factors, such as temperature, clamping force, cutting force, tool geometry, etc., [33][34][35][36][37][38].…”

Section: Methodsmentioning

confidence: 99%

“…The opposite is true for tensile residual stresses, which lower the fatigue resistance and can cause intercrystalline corrosion. Depending on the analysed case, the aim is to create residual stresses with a specific sign or to remove them [9,[15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pre-Machining of Rolled Plates as an Element of Minimising the Post-Machining Deformations

2020

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The paper presents the influence of the milling strategy, the relation between the cutting tool feed direction and the rolling direction, as well as the pre-machining consisting of the removal of the textured surface layer of rolled plates in the rolling process on the thin-walled elements deformations made of the EN AW-2024 T351 wrought aluminium alloy, after milling. The research used strategies such as: high-performance cutting (HPC), high-speed cutting (HSC) and conventional milling (CM), as well as their combinations. Another tested variable was the relation between the tool feed direction and the rolling direction. In addition, the tests were carried out in the following versions: leaving the textured surface layer created after plastic working and with its removal with technological parameters corresponding to HSC and CM. Based on the obtained results, it was found that the post-machining deformation of thin-walled elements can be minimised owing to the use of a selected milling strategy and its combination with pre-machining (or lack thereof). It was also observed that larger deformations were obtained for samples after milling in the direction perpendicular to the rolling direction.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pre-Machining of Rolled Plates as an Element of Minimising the Post-Machining Deformations

2020

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“…Eine Übersicht von Strategien zur gezielten Anpassung von Eigenspannungen in der Massivumformung ist in [9] [11]. Grundsätzlich geht man davon aus, dass Druckeigenspannungen einen positiven Einfluss auf die Zug-und Ermüdungsfestigkeit von Bauteilen aufweisen, wohingegen Zugeigenspannungen einen negativen Einfluss haben [12].…”

Section: Stand Der Technikunclassified

Eigenspannungsorientiertes Fügen von hybriden Bauteilen mittels Radial-Walzen

Guilleaume

Kühne

Kästner

et al. 2021

Forsch Ingenieurwes

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ZusammenfassungFlexible Fertigungsprozesse in der Umformtechnik ermöglichen es, schnell und effizient auf veränderliche Rahmenbedingungen beispielsweise durch Kundenwünsche und rechtliche Anforderungen reagieren zu können. Besonders die inkrementellen Umformverfahren der Massivumformung zeichnen sich durch eine hohe Flexibilität aus, da die Prozesse gut anpassbar sind und die verwendeten Anlagen und Werkzeuge in einem geringeren Maße auf ein spezifisches Bauteil hin ausgelegt werden.Der hier vorgestellte Fügeprozess mittels Radial-Walzen ist geeignet, hybride Bauteile form- und kraftschlüssig miteinander zu verbinden. So lassen sich die spezifischen Vorteile verschiedener Werkstoffe kombinieren und Nutzungs- sowie Leichtbaupotenziale können gezielt genutzt werden. Die in diesem Prozess entstehende charakteristische umlaufende Kerbe in der Wellenkomponente bildet eine Schwachstelle der gefügten Bauteile, da es dort unter Last zu einer Spannungskonzentration kommt, welche die Bildung eines Risses begünstigt. Dieser Herausforderung wird mit einer Kombination der Ausnutzung der Kaltverfestigung des gewählten Werkstoffs (1.7225) und gezielt eingebrachter Druckeigenspannungen in der Kerbe begegnet. Hier liegt der Fokus auf den Druckeigenspannungen, die das Potenzial aufweisen, sich verlängernd auf die Lebensdauer auszuwirken. Sie lassen sich gezielt über eine günstige Wahl des Walzpfads zur Herstellung der Fügeverbindung beeinflussen, wie sowohl in numerischen Analysen als auch durch Eigenspannungsmessungen an Realbauteilen gezeigt wird. Es können sehr hohe Eigenspannungen in der kritischen Zone des Kerbgrunds eingebracht werden, die einen deutlichen Einfluss auf die Lebensdauer haben, wie auch die Lebensdauerberechnungen mittels des Örtlichen Konzepts deutlich zeigen.

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“…The methods for reduction of residual stresses (e.g., heat treatment, seasoning, and vibration method) are widely used in industry. However, all the ways presented have weaknesses, such as decreases in production efficiency and energy losses, as well as generation of significant costs; therefore, efforts were made to eliminate these operations [ 14 , 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

A Comparison of the Geometrical Accuracy of Thin-Walled Elements Made of Different Aluminum Alloys

et al. 2021

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In modern constructions, especially aircraft, the aim is to minimize the weight of the components used. This necessitates the use of innovative construction materials, or the production of these parts with ever-decreasing wall thicknesses. To simplify assembly and improve strength properties, so-called structural elements are being used in the form of monolithic elements, which are replacing the assemblies of parts joined by, for example, riveting. These structures often have a complex, thin-walled geometry with deep pockets. This paper attempts to assess the accuracy of manufacturing thin-walled elements, in the shape of walls with different geometries, made of various aluminum alloys. Machining tests were conducted at different cutting speeds, which allowed comparisons of the geometric accuracy of parts manufactured under conventional and high-speed cutting conditions. Based on the result obtained, it was found that the elements made of EN AW-7075 T651 alloy underwent the greatest deformations during machining in comparison to that of other two materials (EN AW-6082 T651 and EN AC-43000). An increase in the geometrical accuracy of the manufactured elements was also observed with the increase in the cutting speed for the HSC range. Hence, to minimize the postmachining deformation of thin-walled elements, the use of high-speed cutting is justified.

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Observations on the stability of the residual stresses after cold forming and unidirectional loading

Cited by 7 publications

References 16 publications

Pre-Machining of Rolled Plates as an Element of Minimising the Post-Machining Deformations

Pre-Machining of Rolled Plates as an Element of Minimising the Post-Machining Deformations

Eigenspannungsorientiertes Fügen von hybriden Bauteilen mittels Radial-Walzen

A Comparison of the Geometrical Accuracy of Thin-Walled Elements Made of Different Aluminum Alloys

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