scholarly journals Thermal Dissipation Effect on Temperature-controlled Friction Stir Welding

2019 ◽  
Vol 24 ◽  
Author(s):  
Ana Magalhães ◽  
Jeroen De Backer ◽  
Gunnar Bolmsjö
Keyword(s):  
Friction Stir Welding ◽  
Temperature Control ◽  
Tensile Tests ◽  
Fast Response ◽  
Lap Joints ◽  
Thermal Dissipation ◽  
Welding Parameter ◽  
Weld Quality ◽  
Welding Temperature ◽  
Friction Stir

Abstract During Friction Stir Welding (FSW) of complex geometries, the thermal dissipation, induced by geometric features or the surrounding environment, may strongly affect the final weld quality. In order to guarantee a consistent weld quality for different conditions, in-process welding parameter adaptation is needed. This paper studies the effect of thermal dissipation, induced by the backing bar thermal conductivity, on the weld temperature and the temperature controller response to it. A new temperature sensor solution, the Tool-Workpiece Thermocouple (TWT) method, was applied to acquire online temperature measurements during welding. An FSW-robot equipped with temperature control, achieved by rotation speed adaptation, was used. AA7075-T6 lap joints were performed with and without temperature control. The cooling rate during welding was register plus macrographs and tensile tests were assessed. The controller demonstrated a fast response promoting the heat input necessary to maintain the set welding temperature. The results demonstrated that temperature control using the TWT method is suitable to achieve higher joint performance and provides a fast setup of optimal parameters for different environments.

Application of Fuzzy Logic Control Strategy for Temperature Control in Friction Stir Welding

2013 ◽  
Author(s):  
R. R. Varun Das ◽  
V. Kalaichelvi ◽  
R. Karthikeyan
Keyword(s):  
Fuzzy Logic ◽  
Friction Stir Welding ◽  
Dynamic Modeling ◽  
Temperature Control ◽  
Control Strategy ◽  
Welding Process ◽  
Weld Quality ◽  
Production Environment ◽  
Welding Temperature ◽  
Friction Stir

Friction Stir welding is a solid state joining process that utilizes a rotating non-consumable tool to plastically deform and forge together parent metals. Welding can be controlled either by using Force, Temperature and Traverse or Seam Control methods. The presence of numerous parameters and conditional variations in FSW production environment can adversely affect weld quality making extensive automation processes impossible till date. The weld quality of FSW is closely related to the stability of the welding temperature. For such a non-linear complex process conventional control theory is not an appropriate choice. A fuzzy logic controller with a specially chosen triangular membership function has been suggested as an effective alternative approach. The aim of the present work includes dynamic modeling of a friction stir welding process and the use of a suitable Fuzzy tuned Control Strategy for temperature control. The Temperature at stir zone is measured using a K type Thermocouple. It has a sensitivity of 41μV/°C and also a wide variety of probes are available within its −200° C to +1250 °C range. The thermocouple is used by drilling a hole in the shank of the tool and letting it pass through it. The spindle speed is used as an appropriate variable to control temperature variations. The dynamic modeling and simulations were performed using Matlab whereas the variable values were derived during friction stir welding of aluminum.

Temperature Control for Friction Stir Welding of Dissimilar Metal Joints and Influence on the Joint Properties

2018 ◽  
Vol 767 ◽  
pp. 360-368 ◽  
Author(s):  
Markus Krutzlinger ◽  
Roland Marstatt ◽  
Giacomo Costanzi ◽  
Andreas Bachmann ◽  
Ferdinand Haider ◽  
...  
Keyword(s):  
Control System ◽  
Friction Stir Welding ◽  
Temperature Control ◽  
Rotational Speed ◽  
Lap Joints ◽  
Constant Thickness ◽  
Intermetallic Compound Layer ◽  
Welding Temperature ◽  
Friction Stir ◽  
Welding Processes

Friction Stir Welding (FSW) is a suitable technology to join dissimilar metals such as aluminum and copper or aluminum and titanium. Since it is a solid state welding process, the solidus temperature is typically not exceeded and the formation of intermetallic phases can be minimized compared to fusion welding processes. However, an intermetallic layer is still formed at the joining interface. This layer determines the seam properties such as the joint strength or the electrical conductivity. The thickness of the layer is in the nanometer range and is mainly influenced by the welding temperature via an Arrhenius law. The process temperature mainly depends on the rotational speed and on the feed rate of the machine tool. In this study, a temperature control system for aluminum-copper lap joints was developed. A PI control system was used for this purpose to maintain the given welding temperature by adjusting the rotational speed. Consequently, a constant welding temperature was ensured along the entire seam and influences such as changes in workpiece geometry, environmental conditions, or material variations could be mitigated. Experiments with six different temperature levels (low – high) were conducted for one exemplary welding task in order to verify the proposed constant welding conditions. The joints were investigated by tensile shear tests as well as optical and electron microscopy. It was proven that temperature-controlled FSW ensures a constant thickness of the intermetallic compound layer.

scholarly journals Microstructural Characterization and Mechanical Properties of Similar and Dissimilar Al Alloys Joined using Friction Stir Welding

2018 ◽  
Vol 14 (1) ◽  
pp. 19-28
Author(s):  
Kharia Salman Hassan
Keyword(s):  
Friction Stir Welding ◽  
Welding Speed ◽  
Shot Peening ◽  
Rotational Speed ◽  
Microstructural Characterization ◽  
Tensile Tests ◽  
Welding Parameters ◽  
Welding Temperature ◽  
Rotating Speed ◽  
Friction Stir

The influence of pre- shot peening and welding parameters on mechanical and metallurgical properties of dissimilar and similar aluminum alloys AA2024-T3 and AA6061-T6 joints using friction stir welding have been studied. In this work, numbers of plates were equipped from sheet alloys in dimensions (150*50*6) mm then some of them were exposed to shot peening process before friction stir welding using steel ball having diameter 1.25 mm for period of 15 minutes. FSW joints were manufactured from plates at three welding speeds (28, 40, 56 mm/min) and welding speed 40mm/min was chosen at a rotating speed of 1400 rpm for welding the dissimilar pre- shot plates. Tow joints were made at rotational speed of 1000 rpm and welding speed of 40m/min from shot and without shot peening plats. Welding temperature was measured in three zones using thermocouple. Micro hardness (HV) and tensile tests were performed to evaluate the mechanical characteristic of the joints. The results show a decay in mechanical qualities when the welding speed was increased and the best result was at (28) mm/min and the opposite result was obtained when rotational speed increased and pre-shot contributed in improving of this decay at 88% of welding speed (40) mm/min and 98%  at the rotational speed of 1000 rpm.      

Effect of tool parameters on mechanical properties, temperature, and force generation during FSW

2016 ◽  
Vol 233 (6) ◽  
pp. 1033-1043 ◽  
Author(s):  
Mostafa Akbari ◽  
MRM Aliha ◽  
SME Keshavarz ◽  
A Bonyadi
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Critical Role ◽  
Tensile Tests ◽  
Force Generation ◽  
Weld Strength ◽  
Weld Quality ◽  
Friction Stir ◽  
Aa5083 Alloy ◽  
Shoulder Diameter

The welding tool parameters play a critical role in obtaining weld strength during friction stir welding. In this investigation, the effect of welding tool parameters such as pin and shoulder diameter and pin height on the axial and traverse forces and also temperature of welding of AA5083 alloy was investigated. A specially designed dynamometer was used to measure the welding tool forces. Then, the mechanical properties of the welds were characterized using tensile tests. Moreover, macrostructure of welds was investigated in order to analyze weld quality. Finally, optimum values for shoulder diameter, pin height and pin diameter were determined.

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

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 914
Author(s):  
Martina E. Sigl ◽  
Andreas Bachmann ◽  
Thomas Mair ◽  
Michael F. Zaeh
Keyword(s):  
Friction Stir Welding ◽  
Feedback Control ◽  
Control Systems ◽  
Temperature Control ◽  
Welding Parameters ◽  
Work Piece ◽  
Heat Accumulation ◽  
Welding Temperature ◽  
Friction Stir ◽  
Digital Twin

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.

scholarly journals Study on Quality Prediction of 2219 Aluminum Alloy Friction Stir Welding Based on Real-Time Temperature Signal

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3496
Author(s):  
Haijun Wang ◽  
Diqiu He ◽  
Mingjian Liao ◽  
Peng Liu ◽  
Ruilin Lai
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Prediction Model ◽  
Real Time ◽  
Support Vector ◽  
Weld Quality ◽  
Prediction Ability ◽  
Friction Stir ◽  
Temperature Signal ◽  
2219 Aluminum Alloy

The online prediction of friction stir welding quality is an important part of intelligent welding. In this paper, a new method for the online evaluation of weld quality is proposed, which takes the real-time temperature signal as the main research variable. We conducted a welding experiment with 2219 aluminum alloy of 6 mm thickness. The temperature signal is decomposed into components of different frequency bands by wavelet packet method and the energy of component signals is used as the characteristic parameter to evaluate the weld quality. A prediction model of weld performance based on least squares support vector machine and genetic algorithm was established. The experimental results showed that, when welding defects are caused by a sudden perturbation during welding, the amplitude of the temperature signal near the tool rotation frequency will change significantly. When improper process parameters are used, the frequency band component of the temperature signal in the range of 0~11 Hz increases significantly, and the statistical mean value of the temperature signal will also be different. The accuracy of the prediction model reached 90.6%, and the AUC value was 0.939, which reflects the good prediction ability of the model.

scholarly journals Microstructural Evolutions of 2N Grade Pure Al and 4N Grade High-Purity Al during Friction Stir Welding

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3606
Author(s):  
Tomoya Nagira ◽  
Xiaochao Liu ◽  
Kohasaku Ushioda ◽  
Hidetoshi Fujii
Keyword(s):  
Friction Stir Welding ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
High Purity ◽  
Cube Texture ◽  
Grain Structure ◽  
Welding Temperature ◽  
Friction Stir ◽  
Continuous Dynamic Recrystallization ◽  
Dislocation Annihilation

The grain refinement mechanisms along the material flow path in pure and high-purity Al were examined, using the marker insert and tool stop action methods, during the rapid cooling friction stir welding using liquid CO2. In pure Al subjected to a low welding temperature of 0.56Tm (Tm: melting point), the resultant microstructure consisted of a mixture of equiaxed and elongated grains, including the subgrains. Discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and geometric dynamic recrystallization are the potential mechanisms of grain refinement. Increasing the welding temperature and Al purity encouraged dynamic recovery, including dislocation annihilation and rearrangement into subgrains, leading to the acceleration of CDRX and inhibition of DDRX. Both C- and B/-type shear textures were developed in microstructures consisting of equiaxed and elongated grains. In addition, DDRX via high-angle boundary bulging resulted in the development of the 45° rotated cube texture. The B/ shear texture was strengthened for the fine microstructure, where equiaxed recrystallized grains were fully developed through CDRX. In these cases, the texture is closely related to grain structure development.

Microstructure and Mechanical Properties at the Unsteady Areas of Non-Linear Friction Stir Welding

2007 ◽  
Vol 561-565 ◽  
pp. 1059-1062 ◽  
Author(s):  
H. Takahara ◽  
Masato Tsujikawa ◽  
Sung Wook Chung ◽  
Y. Okawa ◽  
Kenji Higashi
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Welding Parameter ◽  
Butt Joints ◽  
Friction Stir ◽  
Non Linear ◽  
Linear Friction ◽  
Fsw Parameters ◽  
Five Axis ◽  
Welding Direction

The influence of tool control in non-linear friction stir welding (FSW) on mechanical properties of joints was investigated. FSW is widely applied to linear joints. It is impossible for five axis FSW machines, however, to keep all the FSW parameters in optimum conditions at non-linear welding. Non-linear FSW joints should be made by compromise with the order of priority for FSW parameters. The tensile test results of butt joints with rectangular change in welding direction on plate plane (L-shaped butt joints) with various welding parameter change. It was found that turn to the retreating side is encouraged when welding direction change. And the method of zero inclination tool angle is effective at non-linear and plane welding.

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