Spray Cooling of Early Extracted Hot Stamped Parts

Nürnberger, Florian; Diekamp, Max; Moritz, Jörn; Wolf, Lars Oliver; Hübner, Sven; Behrens, Bernd‐Arno

doi:10.1002/9781118889879.ch116

Cited by 8 publications

(3 citation statements)

References 8 publications

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“…Während der Abkühlung aus der Umformwärme entwickeln sich die finalen Eigenspannungen im Material in Abhängigkeit von den thermischen und umwandlungsinduzierten Verzerrungen. Die Arbeiten [12,13] und [14]…”

Section: Anlagentechnische Anforderungenunclassified

Numerische Prozessauslegung zur gezielten Eigenspannungseinstellung in warmmassivumgeformten Bauteilen unter Berücksichtigung von Makro- und Mikroskala

Behrens

Schröder

Brands

et al. 2021

Forsch Ingenieurwes

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ZusammenfassungZiel 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 umgeformt und anschließend aus der Schmiedewärme im Wasser abgekühlt werden, aufgezeigt. Vorige Arbeiten zeigen, dass sich Zugeigenspannungen in den derartig umgeformten Proben aus dem Material 1.3505 einstellen. Mittels der vorgestellten mehrskaligen FE-Modelle, wird in dieser Arbeit eine alternative Prozessvariante analysiert, mit der vorteilhafte Druckeigenspannungen anstelle von Zugeigenspannungen durch eine angepasste Abkühlung aus der Umformwärme in den Proben erzeugt werden können. Die angepasste Kühlung wird durch eine partielle Beaufschlagung der Proben mit einem Wasser-Luft-Spray erreicht. Auf diese Weise kann die lokale Plastifizierung durch inhomogene Verzerrungen aufgrund thermischer und umwandlungsinduzierter Effekte beeinflusst werden, um letztlich das Eigenspannungsprofil individuell zu gestalten. Die wissenschaftliche Herausforderung dieser Arbeit besteht darin, unterschiedliche Eigenspannungen in der Oberfläche der Proben zu erzeugen, während die geometrischen und mikrostrukturellen Eigenschaften gleichbleiben. Es wird nachgewiesen, dass eine Beeinflussung der Eigenspannungen und sogar die Umkehr des Spannungsvorzeichens allein durch eine geschickte Prozessführung beim Abkühlen möglich ist.

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Section: Anlagentechnische Anforderungenunclassified

Numerische Prozessauslegung zur gezielten Eigenspannungseinstellung in warmmassivumgeformten Bauteilen unter Berücksichtigung von Makro- und Mikroskala

Behrens

Schröder

Brands

et al. 2021

Forsch Ingenieurwes

Self Cite

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“…A more precise adjustment of the heat-transfer coefficients and thus of the temperature gradients is achieved in [29] and [30] by means of a cooling medium with added polymer solutions in customised concentrations. In addition, the works [31,32] and [33] show that the controlled cooling using a two-phase fluid flow on the basis of a water-air mixture has proved to be very flexible, since both comparatively low heat transfers as in gas quenching and high cooling rates like those in water cooling can be achieved. Thus, a surface tempering of austenitised components like gears [34] and pinion shafts [35] could be realised by controlled spray cooling, with the surface being quenched and tempered by means of the residual internal heat.…”

Section: Introductionmentioning

confidence: 99%

Targeted adjustment of residual stresses in hot-formed components by means of process design based on finite element simulation

et al. 2021

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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 plastification caused by inhomogeneous strains due to thermal and transformation-induced loads can be controlled in order to finally customise the surface-near residual stress distribution. Applications for hot-formed components often require special microstructural properties, which guarantee a certain hardness or ductility. For this reason, the scientific challenge of this work is to generate different residual stress distributions on components surfaces, while the geometric as well as microstructural properties of AISI 52100 alloy stay the same. The changes in the residual stresses should therefore not result from the mentioned changed component properties, but solely from the targeted process control. Within the scope of preliminary experimental studies, tensile residual stresses in a martensitic microstructure were determined on reference components, which had undergone a simple cooling in water (from the forming heat), or low compressive stresses in pearlitic microstructures were determined after simple cooling in atmospheric air. Numerical studies are used to design two tailored cooling strategies capable of generating compressive stresses in the same components. The developed processes with tailored cooling are experimentally realised, and their properties are compared to those of components manufactured involving simple cooling. Based on the numerical and experimental analyses, this work demonstrates that it is possible to influence and even invert the sign of the residual stresses within a component by controlling the macroscopic effects mentioned above.

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“…Although the mainstream of recent developments is towards the use of the CO 2 cryogenic cooling, a window remains for appropriate intensive spray cooling. The MQL might see the potential of the proposed method also with the hot stamping [11,12] and the roller burnishing [13]. Another process receiving much attention lately is the spray cooling during the high pressure die casting [14].…”

Section: Introductionmentioning

confidence: 99%

Remote Cooling of Rolls in Hot Rolling; Applicability to Other Processes

Boháček

Raudenský

Kotrbáček

2021

Metals

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A novel method of cooling rolls in hot rolling is proposed. This method uses a combination of solid jet nozzles and specially shaped deflecting vanes. The vanes transform the incoming cylindrical water jet into a flat fan. Thereby, the coolant can be directed into hardly accessible locations whilst maintaining the optimal angle of impingement. The vanes allow for effectively cooling the roll surface near the rolling gap, which is otherwise not possible with classical flat fan nozzles. The jet impact is tangential due to the limited room for nozzle mounts or a coolant supply. The developed method was laboratory tested. A similar cooling efficiency was found between the vane and the flat fan nozzle. The latter was however mounted in a position impossible in the plant. The potential of the proposed cooling is, therefore, eminent. Apart from hot rolling, it could be exploited in other technological processes such as high pressure die casting, machining, turning, hot stamping, etc.

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Spray Cooling of Early Extracted Hot Stamped Parts

Cited by 8 publications

References 8 publications

Numerische Prozessauslegung zur gezielten Eigenspannungseinstellung in warmmassivumgeformten Bauteilen unter Berücksichtigung von Makro- und Mikroskala

Numerische Prozessauslegung zur gezielten Eigenspannungseinstellung in warmmassivumgeformten Bauteilen unter Berücksichtigung von Makro- und Mikroskala

Targeted adjustment of residual stresses in hot-formed components by means of process design based on finite element simulation

Remote Cooling of Rolls in Hot Rolling; Applicability to Other Processes

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