Towards Process Control of Friction Stir Welding for Different Aluminum Alloys

Fehrenbacher, Axel; Cole, Edward G.; Zinn, Michael; Ferrier, Nicola; Duffie, Neil A.; Pfefferkorn, Frank E.

doi:10.1002/9781118062302.ch44

Cited by 11 publications

(6 citation statements)

References 9 publications

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“…A 0-D heat conduction model recalculated this surface temperature into a welding temperature [22]. In subsequent investigations, the scientists used thermocouples integrated into the tool to improve the temperature measurement [23,24].…”

Section: Force and Temperature Control Approaches For Joining Processesmentioning

confidence: 99%

A Holistic, Model-Predictive Process Control for Friction Stir Welding Processes Including a 1D FDM Multi-Layer Temperature Distribution Model

Meyer

Fuderer

Zaeh

2021

Metals

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Friction press joining is an innovative joining process for bonding plastics and metals without additives in an overlap configuration. This paper presents for the first time a model-based approach for designing a multi-variable model predictive control (MPC) for friction press joining. For system modeling, a differential equation based on the heat flows was proposed and modeled as a torque-dependent function. With this model, it is possible to consider cross-effects between the axial force and the friction zone temperature. With this theoretical approach, adaptive model-predictive process control was implemented and validated for different material combinations (EN AW-6082-T6; EN AW-2024-T3; PE-HD; PA6-GF30; PPS-CF). It could be shown that the MPC has excellent control accuracy even when model uncertainties are introduced. Based on these findings, a 1D Finite Differential Method multi-layer model was developed to calculate the temperature in the plastic component, which is not measurable in situ (r = 0.93). These investigations demonstrate the high potential of the multi-variable MPC for plastic-metal direct joining.

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Section: Force and Temperature Control Approaches For Joining Processesmentioning

confidence: 99%

A Holistic, Model-Predictive Process Control for Friction Stir Welding Processes Including a 1D FDM Multi-Layer Temperature Distribution Model

Meyer

Fuderer

Zaeh

2021

Metals

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“…Earlier DOE studies on copper canisters 11,12 have shown that the tool rotation rate is the most important and suitable factor for controlling the tool temperature, while other studies have used welding speed changes to control the tool temperature during welds with non-uniform thermal boundary conditions. 17…”

Section: Parameter Relationshipsmentioning

confidence: 99%

Improved process stability during friction stir welding of 5 cm thick copper canisters through shoulder geometry and parameter studies

Cederqvist¹,

Sorensen²,

Reynolds³

et al. 2009

Science and Technology of Welding and Joining

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The spent nuclear fuel from Swedish power plants will be placed in copper canisters that are sealed with friction stir welding and the stability and robustness of this process is now being optimised in three steps: first, the shoulder geometry was identified that produced the most stable weld cycle, then the welding parameters were optimised for that geometry with regards to stability, and finally, the chosen geometry and welding parameters were verified and evaluated during multiple weld cycles. The shoulder study showed that stable welds could be produced repeatedly with a convex scroll geometry which proved more stable than various concave and flat scroll geometries. In the subsequent parameter study, not only were the most stable values for the welding parameters derived, but a clear relationship was shown between power input and tool temperature. This relationship can be used to more accurately control the process within the parameter windows, not only for this application but for other applications where the welding temperature needs to be kept within a specified range. Similarly, the potential of the convex scroll shoulder geometry for use in applications with other metals and thicknesses is evident.

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“…It has already been shown that controlling the welding temperature during FSW is a key method for ensuring high quality welds [4,5]. Therefore, several approaches for controlling the welding temperature during FSW have been postulated over the years [6][7][8][9][10][11][12][13][14][15][16][17]. Studies have shown that joint defects, such as flash formation, can be reduced or even prevented [6,8,18] and the layer thickness of intermetallic compounds in dissimilar joints can be adjusted by temperature control [19].…”

Section: Introductionmentioning

confidence: 99%

Torque-Based Temperature Control in Friction Stir Welding by Using a Digital Twin

Sigl

Bachmann

Mair

et al. 2020

Metals

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Friction stir welding (FSW) is an innovative solid-state welding technology that produces high quality joints and is widely used in the aerospace industry. Previous studies have revealed welding temperature to be a decisive factor for joint quality. Consequently, several temperature control systems for FSW have been developed. These output feedback control systems usually require delicate and expensive temperature measuring equipment, which reduces their suitability for industrial practice. This paper presents a novel state feedback system of the welding temperature to remedy this shortcoming. The system uses a physical model of the FSW process (digital twin) for the determination of the welding temperature signal from the process torque signal. The digital twin is based on a multi-input nonlinear time invariant model, which is fed with the torque signal from the spindle motor. A model-based L1 adaptive controller was employed for its robustness with respect to model inaccuracies and fast adaption to fluctuations in the controlled system. The experimental validation of the feedback control system showed improved weld quality compared to welded joints produced without temperature control. The achieved control accuracies depended on the results of the temperature calculation. Control deviations of less than 10 K could be achieved for certain welding parameters, and even for a work piece geometry, which deliberately caused heat accumulation.

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Towards Process Control of Friction Stir Welding for Different Aluminum Alloys

Cited by 11 publications

References 9 publications

A Holistic, Model-Predictive Process Control for Friction Stir Welding Processes Including a 1D FDM Multi-Layer Temperature Distribution Model

A Holistic, Model-Predictive Process Control for Friction Stir Welding Processes Including a 1D FDM Multi-Layer Temperature Distribution Model

Improved process stability during friction stir welding of 5 cm thick copper canisters through shoulder geometry and parameter studies

Torque-Based Temperature Control in Friction Stir Welding by Using a Digital Twin

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