scholarly journals Adaptive Control of Resistance Spot Welding Based on a Dynamic Resistance Model

2019 ◽  
Vol 24 (4) ◽  
pp. 86 ◽  
Author(s):  
Kas ◽  
Das
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Controller Design ◽  
Welding Process ◽  
Dynamic Resistance ◽  
Resistance Spot ◽  
Control Scheme ◽  
Metal Sheets ◽  
One Step ◽  
Welding Processes

Resistance spot welding is a process commonly used for joining a stack of two or three metal sheets at desired spots. Such welds are accomplished by holding the metallic workpieces together by applying pressure through the tips of a pair of electrodes and then passing a strong electric current for a short duration. This kind of welding process often suffers from two common drawbacks, namely, inconsistent weld quality and inadequate nugget size. In order to address these problems, a new theoretical approach of controlling resistance spot welding processes is proposed in this paper. The proposed controller is based on a simplified dynamical model of the resistance spot welding process and employs the principle of adaptive one-step-ahead control. It is essentially an adaptive tracking controller that estimates the unknown process parameters and adjusts the welding voltage continuously to make sure that the nugget resistance tracks a desired reference resistance profile. The modeling and controller design methodologies are discussed in detail. Also, the results of a simulation study to evaluate the performance of the proposed controller are presented. The proposed control scheme is expected to reduce energy consumption and produce consistent welds.

A Comparative Study of AC and MFDC Resistance Spot Welding

2004 ◽  
Author(s):  
Wei Li ◽  
Daniel Cerjanec
Keyword(s):  
Comparative Study ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Welding Current ◽  
Median Frequency ◽  
Resistance Spot ◽  
Secondary Voltage ◽  
Nugget Growth ◽  
Welding Processes

This paper presents a comparative study of the AC and MFDC resistance spot welding process. Two identical welders were used; one with a single phase AC and the other with a median frequency DC weld control. Both welders were instrumented such that the primary and secondary voltage and current could be collected. A nugget growth experiment was conducted to compare the weld size and energy consumption in the AC and MFDC welding processes. It is found that the MFDC process generally produces larger welds with the same welding current. However, this difference is more prominent when the welding current is low. Overall the AC welding process consumes more energy to make a same size weld. The larger the welding current is used, the less efficient the AC process becomes.

A new measurement method for the dynamic resistance signal during the resistance spot welding process

2016 ◽  
Vol 27 (9) ◽  
pp. 095009 ◽  
Author(s):  
Lijing Wang ◽  
Yanyan Hou ◽  
Hongjie Zhang ◽  
Jian Zhao ◽  
Tao Xi ◽  
...  
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Measurement Method ◽  
Welding Process ◽  
Dynamic Resistance ◽  
Resistance Spot

scholarly journals Effect of Zinc Coating on Delay Nugget Formation in Dissimilar DP600 - AISI304 Welded Joints Obtained by the Resistance Spot Welding Process

2021 ◽  
Author(s):  
Mercedes Pérez de la Parte ◽  
Alejandro Espinel Hernández ◽  
Mario César Sánchez Orozco ◽  
Angel Sánchez Roca ◽  
Emilio Jiménez Macias ◽  
...  
Keyword(s):  
Welded Joints ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Zinc Coating ◽  
Welding Process ◽  
Dynamic Resistance ◽  
Time Duration ◽  
Resistance Spot ◽  
Nugget Formation ◽  
Resistance Curves

Abstract This paper researches the effect of zinc coating of galvanized DP600 steel on the dynamic resistance and the delayed nugget formation of dissimilar DP600 - AISI304 welded joints, obtained with resistance spot welding process (RSW). The RSW evaluations consisted of determining, from the dynamic resistance curves, the time involved in the different stages of the process, particularly the beginning of nugget formation. The experimental results showed that, from the dynamic resistance curves, it is possible to identify 8 distinct stages during the welding of galvanized DP600 steel and AISI304 stainless steel. In the case of the welding of uncoated DP600 steel with AISI304, only 6 stages are identified (except for stages 2 and 3), which are directly related to the heating, softening and melting of the galvanic coating. The energy used in stages 2 and 3, causes a delay in the beginning of nugget formation for welded joints obtained with galvanized DP600 steel compared to uncoated DP600 - AISI304 welded joints, reaching values between 37.28 ms and 52.29 ms for the welding conditions analyzed. Monitoring the time duration of stages 2 and 3, as defined from the analysis of the dynamic resistance curves, could be used as a tool to predict the beginning of nugget formation in the welding of galvanized steels, to avoid undesirable phenomena such as expulsion and to guarantee the quality of the welded joints.

scholarly journals Modified Recurrence Plot for Robust Condition Monitoring of Electrode Tips in a Resistance Spot Welding System

2020 ◽  
Vol 10 (17) ◽  
pp. 5860
Author(s):  
Wonho Jung ◽  
Hyunseok Oh ◽  
Dong Ho Yun ◽  
Young Gon Kim ◽  
Jong Pil Youn ◽  
...  
Keyword(s):  
Condition Monitoring ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Recurrence Plot ◽  
External Noise ◽  
Dynamic Resistance ◽  
Resistance Spot ◽  
Welding Electrode ◽  
Welding System

Degraded electrodes in a resistance spot welding system should be replaced to ensure that weld quality is maintained. Welding electrodes are subjected to different environmental and operational loading conditions during use. When they are replaced with a fixed interval, replacement may occur too early (raising maintenance costs) or too late (leading to quality issues). This motivates condition monitoring strategies for resistance spot welding electrode tips. Thus, this paper proposes a modified recurrence plot (RP) for robust condition monitoring of welding electrode tips in resistance spot welding systems. The overall procedure for the proposed condition monitoring approach consists of three steps: (1) transformation of a one-dimensional signal to a two-dimensional image, (2) unsupervised feature extraction with LeNet architecture-based convolutional neural networks, and (3) health indicator calculation. RP methods convert dynamic resistance waveforms to RPs. The original RP method provides an image with binary-colored pixels (i.e., black or white) that makes this method insensitive to the change of the waveform signal. The proposed RP method is devised to be sensitive to the change of the waveform signal, while enhancing robustness to external noise. The performance of the proposed RP method is evaluated by examining simulated aperiodic waveform signals with and without external noise. A case study is presented to examine the proposed method’s ability to monitor the condition of resistance spot welding electrodes. The results show that the proposed method outperforms handcrafted, feature-based condition monitoring methods. This study can be used to accurately determine the lifetime of welding electrodes in real time during the spot welding process.

Evaluation of the Role of Eddy Current in Resistance Spot Welding

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
M. Abu-Aesh ◽  
Moataza Hindy
Keyword(s):  
Eddy Current ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Welding Current ◽  
Work Piece ◽  
Resistance Spot ◽  
Precise Prediction ◽  
Welding Processes

Extensive work had been conducted on spot-welding due to its rapidly increasing industrial importance. The resistance spot-welding involves complicated phenomena, as several effects are found in the process, e.g., temperature, surface roughness, pressure, and eddy current effects. Most of the work exerted for analyzing the spot-welding process neglect the effect of the eddy current generated during the flow of the huge welding main current through the assembly of electrodes and work sheets. This work presents an analytical method to investigate the generation of eddy current and to determine the total effective welding current in spot-welding. The current distribution on the work sheet when it is fed by a conducting electrode is also investigated. The obtained current formula is based on electromagnetic principles, where a very strong magnetic field is generated in the core of the electrodes as well as in the materials of work sheets due to the flow of very high amperage. The final resultant effective current is the superposition of the electrode welding current and the induced eddy current in the electrode and work piece assembly. The results offer a viable mathematical model, which can be applied for a precise prediction of the effective value of welding current in spot-welding processes, if applied in a comprehensive model including all involved effects.

Significance of Workpiece Conductivity on Resistance Spot Welding Process Map

2019 ◽  
Author(s):  
Xin Wu ◽  
Jingtao Du ◽  
Wayne Cai
Keyword(s):  
Steady State ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Heat Dissipation ◽  
Operation Mode ◽  
Welding Process ◽  
Process Window ◽  
Welding Condition ◽  
Resistance Spot ◽  
Welding Processes

Abstract Resistance spot welding (RSW) is a sheet metal welding process with broad applications, known to be more suitable for low-conductive materials, such as steels, due to concentrated and steady-state heat generation and retention at the metal interface. However, for high conductive metals such as copper, conventional welding processes in resistance spot welding has not been successful. This paper provides a comparative study of resistance welding among steel, aluminum and copper through mechanistic analyses, i.e., analytical solutions calibrated by finite element analyses. It is found when lower conductivity metals, such as steels, are welded, the applied energy can be more concentrated on the interfaces, and the heat dissipation is relatively slow, so that a close to steady-state welding condition can be reached that provides a wide and robust operation window. For welding highly conductive metals having similar melting temperature as that of electrode, the process window becomes much narrower or does not always exist without additional conditioning of materials, design or the welding processes. The physics of RSW process is analyzed based on energy equilibrium, and a new concept of pulse welding process is proposed as a required operation mode for welding copper during temperature ramping up period and prior to electrode melting. A new type of welding limit diagram (WLD) is constructed that contains three welding limit curves (WLC) for nugget formation, and the transient region. The newly constructed WLD allows a clear distinction between welding low- and high-conductive metals, and provides new understanding and a theoretical guidance for widening the weldability window.

scholarly journals Analysis of the Behavior of Dynamic Resistance, Electrical Energy and Force between the Electrodes in Resistance Spot Welding Using Additive Manufacturing

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 690
Author(s):  
Márcio Batista ◽  
Valdir Furlanetto ◽  
Sérgio Duarte Brandi
Keyword(s):  
Thermal Expansion ◽  
Additive Manufacturing ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Electrical Energy ◽  
Dynamic Resistance ◽  
Low Carbon ◽  
Resistance Spot ◽  
Welding Spot

This work is aimed at the analysis of the dynamic resistance, electrical energy and behavior of the force between electrodes (including thermal expansion) during welding at optimized parameters, referring to the process of spot welding using additive manufacturing (AMSW). For comparative purposes, this analysis also includes the conventional resistance spot welding process (RSW). The experiments were done on low carbon-zinc-coated sheets used in the automotive industry. The results regarding the welding process using additive manufacturing (AMSW), in comparison to the conventional resistance spot welding (RSW), showed that the dynamic resistance presented a different behavior due to the collapse of the deposition at the beginning of the welding, and that a smaller magnitude of electrical energy (approximately <3.35 times) is required to produce a welding spot approved in accordance with the norm. No force of thermal expansion was observed during the passage of the current, in contrast, there was a decrease in the force between the electrodes due to the collapse of the deposition at the beginning of the welding.

scholarly journals Embedded Artificial Neuval Network-Based Real-Time Half-Wave Dynamic Resistance Estimation during the A.C. Resistance Spot Welding Process

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Liang Gong ◽  
Yan Xi ◽  
Chengliang Liu
Keyword(s):  
Real Time ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Measuring Method ◽  
Computing System ◽  
Dynamic Resistance ◽  
Resistance Spot ◽  
Half Wave ◽  
Artificial Neural Network Ann

Online monitoring of the instantaneous resistance variation during the A.C. resistance spot welding is of paramount importance for the weld quality control. On the basis of the welding transformer circuit model, a new method is proposed to measure the transformer primary-side signal for estimating the secondary-side resistance in each 1/4 cycle. The tailored computing system ensures that the measuring method possesses a real-time computational capacity with satisfying accuracy. Since the dynamic resistance cannot be represented via an explicit function with respect to measurable parameters from the primary side of the welding transformer, an offline trained embedded artificial neural network (ANN) successfully realizes the real-time implicit function calculation or estimation. A DSP-based resistance spot welding monitoring system is developed to perform ANN computation. Experimental results indicate that the proposed method is applicable for measuring the dynamic resistance in single-phase, half-wave controlled rectifier circuits.

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