Innovative Online Measurement and Modelling Approach for Property-Controlled Flow Forming Processes

Kersting, Lukas; Arian, Bahman; Vasquez, Julian Rozo; Trächtler, Ansgar; Homberg, Werner; Walther, Frank

doi:10.4028/p-yp2hj3

Cited by 6 publications

(9 citation statements)

References 13 publications

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“…The process and material were already used in previous publications of the authors. Thus, it is referred to [7,8] for additional information.…”

Section: Setupmentioning

confidence: 99%

Control strategy for angular gradations by means of the flow forming process

Kersting

2023

Materials Research Proceedings

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Abstract. Climate change, rare resources and industrial transformation processes lead to a rising demand of multi-complex lightweight forming parts, especially in aerospace and automotive sectors. In these industries, flow forming is often used to produce cylindrical forming parts by reducing the wall thickness of tubular semifinished parts, e.g. for the production of hydraulic cylinders or gear shafts. The complexity and functionality of flow forming workpieces could be significantly increased by locally graded microstructure and geometry structures. This enables customized complex hardness distributions at wear surfaces or magnetic QR codes for a unique, tamper-proof product identification. The production of those complex, 2D (axial and angular) graded forming parts currently depicts a great challenge for the process and requires new solutions and strategies. Hence, this paper proposes a novel control strategy that includes online measurements from an absolute encoder to determine the angular workpiece position. Workpieces of AISI 304L stainless steel with 2D-graded structures are successfully manufactured using this new strategy and analyzed regarding the possible accuracy and resolution of the gradation. At this point, a dependency of the gradations on the sensor and actuator dynamics, accuracy and geometry could be noted. It is further evaluated how the control strategy could be extended by an observer-based closed-loop property control approach to enhance the accuracy of the suggested strategy.

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“…The process and material were already used in previous publications of the authors. Thus, it is referred to [7,8] for additional information.…”

Section: Setupmentioning

confidence: 99%

Control strategy for angular gradations by means of the flow forming process

Kersting

2023

Materials Research Proceedings

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“…Iterative, model-based toolpath planning for the actual process thus leads to deviations between the desired and the resulting workpiece. The authors already proposed an online closed-loop property and process control to counter this challenge (see [9,20]). Closed-loop During the forming on the actual machine, the workpiece is monitored by moving sensors coupled with the machine support and measuring the actual workpiece properties: two laser distance sensors for the wall thickness reduction to ensure the workpiece geometry and a micromagnetic (soft-)sensor to supervise the α'-martensite fraction (see also [9,20]).…”

Section: Model-based Closed-loop Process Controlmentioning

confidence: 99%

“…The authors already proposed an online closed-loop property and process control to counter this challenge (see [9,20]). Closed-loop During the forming on the actual machine, the workpiece is monitored by moving sensors coupled with the machine support and measuring the actual workpiece properties: two laser distance sensors for the wall thickness reduction to ensure the workpiece geometry and a micromagnetic (soft-)sensor to supervise the α'-martensite fraction (see also [9,20]). The wall thickness reduction Δ𝑤 here is calculated by the difference between the wall thickness in the unformed workpiece area 𝑤 0 and the formed section 𝑤 1 .…”

Section: Model-based Closed-loop Process Controlmentioning

confidence: 99%

“…It was successfully validated for the measured wall thickness reduction Δ𝑤 as the control variable, the infeed depth Δ𝑟 as the manipulated variable and a constant feed 𝑓 in previous investigations of the authors. For designing the controller, a novel system model presented in [20] was used in MATLAB/Simulink as a proof of concept. This system model of the flow forming process includes a discretization of the workpiece, an empirical black-box plastic deformation model, the Olson-Cohen-based material model of martensite formation (see section 2.3), a sensor model and the control loop, but force-related effects like friction and residual stresses were disregarded.…”

Section: Model-based Closed-loop Process Controlmentioning

confidence: 99%

“…It is thus planned to enhance the system model accuracy by integrating the novel flow forming FE process model. However, this model coupling of the system simulation and FEM depicts a challenge because of the different simulation duration: System simulation amounts a duration of less than 1 minute using the system model from [20]. The presented FE model requires days of simulation time for calculation by contrast.…”

Section: Model-based Closed-loop Process Controlmentioning

confidence: 99%

See 2 more Smart Citations

A flow forming process model to predict workpiece properties in AISI 304L

Arian¹,

Oesterwinter

Homberg

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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The control of workpiece properties enables an application-oriented and time-efficient production of components. In reverse flow forming, e.g., the control of the microstructure profile, in contrast to the adjustment of the geometry, is not yet part of the state of the art. This is particularly challenging when forming seamless tubes made of metastable austenitic stainless AISI 304L steel. In this steel, a phase transformation from austenite to martensite can occur due to mechanically and/or thermally induced energy. The α’-martensite has different mechanical and micromagnetic properties, which can be advantageous depending on the application. For the purpose of local property control, the resulting α’-martensite content should be measured and controlled online during the forming process. In this paper, results from an empirical correlation model of process parameter combinations and resulting α’-martensite content as well as geometry will be presented. Based on this, the focus of the paper will be on process modeling by means of FEM in order to create the transition to a numerically supported process model. Furthermore, it will be specified how the numerical process model can be used in a predictive manner for an online closed-loop process control.

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Influence of Press‐Hardening in Combination with Quenching and Partitioning Treatment on the Microstructure of Medium Manganese Steel

Blankart

Emmrich

Bähren

et al. 2023

steel research int.

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Press‐hardening of manganese–boron steels is one of the most efficient production processes for high‐strength automotive components. However, the residual formability of these sheet components is greatly limited by the formation of fully martensitic microstructure. Herein, to extend the application of press‐hardened components also to impact energy‐absorptive parts of the vehicle body, the potential of press‐hardening of a medium manganese steel in combination with a quenching and partitioning (Q&P) treatment is analyzed. Therefore, selected heat treatments from prior dilatometer investigations are reproduced in a laboratory‐scale press‐hardening system equipped with a heated hat‐shaped tool. Instead of a complete martensitic microstructure, the Q&P process leads to a multiphase microstructure consisting of fresh and tempered martensite as well as retained austenite with different carbon content each. Since depending on the phase fractions also strongly different mechanical properties are expected, not only the qualitative distinction but also the quantitative determination of the martensitic phases is of extraordinary importance. Herein, it is shown that using phase maps combined with grain‐average band slope of electron backscatter diffraction measurements is a suitable method to distinguish quantitatively fresh and tempered martensite. Validation of the differentiation method is performed using electron‐probe microanalysis.

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Innovative Online Measurement and Modelling Approach for Property-Controlled Flow Forming Processes

Cited by 6 publications

References 13 publications

Control strategy for angular gradations by means of the flow forming process

Control strategy for angular gradations by means of the flow forming process

A flow forming process model to predict workpiece properties in AISI 304L

Influence of Press‐Hardening in Combination with Quenching and Partitioning Treatment on the Microstructure of Medium Manganese Steel

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