Welding Quality Control Research Articles

Study on the Numerical Simulation of the Resistance Spot Welding Process of Magnesium Alloy

Spot welding of magnesium alloy was a complex processes of thermal, electrical, mechanical and metallurgical mutual coupling, meanwhile its’ low melting point, high thermal conductivity, and high linear expansion coefficient increased the welding quality control difficultly. Basing on SYSWELD, a numerical simulation of effects of welding current, welding time, thickness of plate, electrode pressure gauge and size on the nugget shape and welding quality of ZA31B was demonstrated. The relationship between the size of the nugget dimensions and the welding parameters was established by a large number of simulation and experimental study. The experimental results showed that the analogue result was consistent with the test results, and it could be used to guide the actual production.

Soft computing methods used for the modelling and optimisation of Gas Metal Arc Welding: a review

The quality of a weld primarily depends on the process parameters in any welding process. The welding parameters influence the weld bead geometry and weld microstructure, which is related to mechanical properties. It indicates the necessity to establish the relationship between process variables and weld quality characteristics. The Gas Metal Arc Welding (GMAW) processes are highly non-linear and coupled multivariable systems. It suggests the need for an intelligent system to evaluate the process and to determine the best adjustment. The soft computing techniques provide an alternative method for learning, predictive modelling, optimisation and control of weld quality without any mathematical model. This review illustrates the importance of soft computing tools for prediction, optimisation and control of GMAW processes.

ステンレス鋼製鉄道車両構体の製造プロセスにおけるレーザ溶接品質確保の検討

ステンレス鋼製鉄道車両構体の製造プロセスにおけるレーザ溶接品質確保の検討

Research on Correlation between Weld Concavity and Weld Process Parameters in Tailored Blank Laser Welding

Weld quality control is of great importance in tailored blank laser welding for the purpose of making products at a high quality and high productivity. In general, the controllable parameters are only indirect data on features of the final weld to be made. In this paper, direct correlation between weld concavity and weld process parameters including weld gap and torch offset are discussed based on theoretical analyses and experiments. A direct control model is established according to the analysis of reasons causing weld concavity. This model will improve the quality of laser welding process by accurately controlling the weld geometry in real time.

Application of Current Gain Compensation Method in Quality Control of Resistance Spot Welding of Galvanized Steel Plate

In this paper, the control method of current gain compensation for welding is adopted. Precise current gain curves (i.e., current step curves) in resistance spot welding of galvanized steel plated are discussed and drawn. By analysis of failure of electrode cap, it indicates that new current step curve ensure that qualified welding spot nugget dimension is acquired. The welding spot is high in strength, stable and reliable in quality. It is superior to original current step curve.

An Investigation of Failure Types in High-Strength Steel Resistance Spot Welds

On the shop floor, as in laboratories, destructive testing remains the main means of quality control of spot welds. After hand or mechanized weld destruction, the so-called “plug diameter” is measured and is usually considered a good indicator of the weld quality. However, it turns out that the “plug” failure of spot welds is far from being the rule. Moreover, fracture may occur in different zones of the weld, leading to very different meanings of the plug diameter. Therefore, the plug diameter is most of the time not well-correlated with the weld strength, which is the main value of the spot weld. Partial or full interfacial failures (through the weld nugget) exhibit equivalent mechanical strengths and therefore should not be rejected. Through this work, it is shown that the failure type depends on various parameters (nugget diameter, sheet thickness, loading mode, …), and consequently, it is not an intrinsic property of the steel grade. In this way, recommended quality criteria are based on weld strength, weld diameter (including the interfacial fracture area if any), or absorbed energy independently of failure occurrence. In addition, non-destructive techniques might be key investigation methods and have to be developed further.

프리캐스트 콘크리트 벽체 수직접합부의 광폭형 연결방식 개발

이 연구에서는 프리캐스트 콘크리트 구조시스템에서 기존에 사용되고 있는 벽체의 수직접합부의 시공 및 문제점을 최소화하기 위해 접합부의 폭을 100 mm에서 150 mm로 증가시키고 연결방식을 3가지로 하여 구조적 성능 및 적용성에 대해 분석하였다. 또한, 해석적으로 구조적 성능을 파악하기 위해 비선형 유한 요소 해석법으로 분석하였다. 분석 결과, 광폭형 연결부를 가진 접합부를 적용하였을 때, PC벽체에 가해지는 하중을 더 효율적으로 철근이 분담하여 내력이 증가하고 연성적인 거동을 하는 것으로 나타났다. 또한, 접합부 루프근의 단면적이 커질수록 그리고 철근 개수가 증가할수록 최대내력이 증가하며 광폭형 접합부 형식 중에 용접형-링형-C형의 순서로 내력이 큰 것으로 나타났다. 용접형의 경우 현장조건에 따른 변화가 발생할 수 있으므로 광폭형 연결 부위를 링형 접합부로 하는 것이 안정적인 거동을 하며 현장 용접의 철저한 품질관리가 필요하다.

Intelligent methodology for sensing, modeling, and control of weld penetration in robotic welding system

PurposeThe purpose of this paper is to develop an efficient online monitoring system. It can improve the welding quality through the real‐time analysis of the welding image information.Design/methodology/approachIn this paper, a set‐variable precision rough set (VPRS) modeling method was improved and the prediction model of back‐side bead width dynamic response for robotic arc welding process is proposed. Back‐side width based on the vision sensor in the compound controller is used. Meantime, a compound intelligent controller is designed with the wire‐feeding rate compensation.FindingsThe dynamical information of the top‐side weld pool can be captured in real‐time. Moreover, VPRS prediction model could provide the back‐side bead width of the weld, which integrated with the fuzzy neural network controller. Therefore, more uniform weld penetration can be achieved with the variation of the assembling gap.Research limitations/implicationsThe monitor system requires that the information of the weld pool and the front gap can be extracted precisely. Moreover, the front assembling gap should be limited in a certain interval [0∼3 mm]. This puts forward high request to image processing algorithm and the assembling of the work‐piece.Practical implicationsThis monitor system is applicable to the manufacturing of the spherical head petals in rocket storage tank.Originality/valueThe paper demonstrates that the compound intelligent controller based on the VPRS prediction is possible and effective. The experiments show that the real‐time and precision requirements for monitoring and control of weld quality can be satisfied by using this online control system during welding process.

An online real time ultrasonic NDT system for the quality control of spot welding in the automotive industry

Resistance spot welding is the main joining technique used for the fabrication of body-in-white structures in the automotive industry. The quality of the welds depends on the profile of the spot welding electrode cap. The increased use of zinc coated steel in the industry increases wear rate of the caps, making quality control more difficult. This paper presents a novel online real time ultrasonic NDE system for resistance spot welding which evaluates every weld as it is formed. SEM results are presented to show the alloying of the electrode caps.

An online real time ultrasonic NDT system for the quality control of spot welding in the automotive industry

Resistance spot welding is the main joining technique used for the fabrication of body-in-white structures in the automotive industry. The quality of the welds depends on the profile of the spot welding electrode cap. The increased use of zinc coated steel in the industry increases wear rate of the caps, making quality control more difficult. This paper presents a novel online real time ultrasonic NDE system for resistance spot welding which evaluates every weld as it is formed. SEM results are presented to show the alloying of the electrode caps.

Development of Condition Monitoring System for Laser Welding System of Stainless Steel Sheets

The method of the quality control in the laser welding has various techniques. The laser welding monitor system is one of the many kinds of technique concerning of quality control, and is marketed. However, it is necessary not only to manage in-process in the welding system but also to manage pre-process and post-process to control welding quality. Therefore, the management of the welding quality needs the monitoring in the above method. As the first, the condition monitoring technique uses the waveform analysis of the optical intensity in in-process of the laser welding process. In this report, the application experience to the half penetration welding with the YAG laser for thin stainless steel sheets is discussed.

Vibration Welding Quality Control using Piezoelectric Shear Stress Transducers

The quality control (QC) of welded parts is a critical manufacturing step. Although QC can be performed on the finished part, identification of defects during the manufacturing process is preferred to minimize the value associated with defective parts. In this paper, the use of piezoelectric shear stress transducers mounted on vibration welding fixtures is presented as a real-time QC tool. Laboratory studies complemented with welding trials on industrial air-intake manifolds show that this technology can be used to identify defects such as incomplete weld beads.

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Quality Measure and Control System for the Whole Process of Arc Welding

Welding quality control is critical for welding manufacturing. However, the factors that affect welding quality exist in the whole welding process. Whole process welding quality control is a technology control process that can control the welding quality from choice of the welding material, stability of the welding process and quality assurance after welding. In this paper, a quality measure and control system is developed. The system is consisted of three modules: Technology property evaluation and welding material choice module is based on Analysator Hannover. This module can evaluate three type of welding material: electrode, solid welding wire and flux-cored wire. The welding process stability evaluation module can collect electrical and light spectral signal for disturbance factors diagnosis during the welding. The metallurgical structure and property forecasting module call the CCT diagram data base for predicting he metallurgical structure and mechanical property of the weld affected zone and weld metal. For stainless steel, a predicting method based on Schaeffer is also provided in this module.

RV 차량용 싱킹 시트의 용접 품질 검사 시스템 개발

This paper presents a vision based autonomous inspection system for welding quality control of a RV sinking seat. In order to overcome the precision error that arises from a visible inspection by an operator in the manufacturing process of a RV sinking seat, the machine vision based welding quality control system is proposed. It consists of the CMOS camera and the NI vision system. The geometry of the welding bead, which is the welding quality criteria, is measured by using the captured image with a median filter applied on it. The image processing software for the system was developed using the NI LabVIEW software. The proposed welding quality inspection system for RV sinking seat was verified using experimentation.

Weld Quality Inspection Based on Online Measured Indentation From Servo Encoder in Resistance Spot Welding

Since resistance spot welding has become the dominant method for car body assembly, studies on spot welding quality control and inspection are becoming more and more important and urgent for the automobile industry. Compared to the traditional air gun, the servo gun spot welding system has the advantages of precise control and feedback of electrode position and pressure. Therefore, it provides the possibility of controlling and inspecting weld quality online. By using the electrode position feedback function of the servo gun, this paper proposes a method for online weld quality inspection based on weld indentation. During a welding process, a weld indentation is extracted from a servo encoder under various welding failures. Then, a weld lobe, which is based on indentation, is built to identify the range for good welds. Finally, experimental data are presented to prove that this method can effectively achieve online weld quality inspection.

ONLINE CONTROL SENSORS FOR WELDING PROCESSES BASED ON OPTICAL RECOGNITION

In the automotive industry, laser welding processes increasingly replace conventional welding methods. The remaining flaw rate of the final product has to be below 5 parts per million (ppm). Therefore, the demands on quality control systems are correspondingly high. Only a combination of sophisticated plasma monitoring, power measurement, and image processing techniques can reliably maintain such low residual flaw rates in production. Plasmo™ is a modular system for automated online quality control of continuous wave laser welding and brazing processes widely used in the automotive industry. An overview of the features and physical background of the plasmo™ system is presented, and its capabilities are demonstrated in a representative example. The standard algorithms and signals in the time domain for online detection of failures and flaws are outlined, as well as new algorithms for special laser welding processes, like e.g. pulsed Nd:YAG laser welding, laser brazing. The potential and capabilities of time series analyses of the process signals are discussed.

Ultrasonic phased array inspection technology for the evaluation of friction stir welds

This paper is based upon a project 'Qualistir' for the on-line quality control of friction stir welds (FSW) in aluminium ( 1 ) . Qualistir is a collaborative project lead by R/D-Tech with co-industrial partners Vermont, Isotest, Neos Robotics and Gatwick Fusion, and research partners TWI, GKSS and TUS. The objective of the project is to develop an on-line method for determining the quality of FSW in a butt-welded configuration. The inspection technique described in this paper detects conventional defects and supplies a method for determining whether the weld has been correctly forged which, in turn, safeguards against joint line remnant defects.

Laser Welding Quality Monitoring with an Optical Fiber System

We have developed a laser welding monitoring system to monitor laser welding process conditions such as sample feed rate, laser focal position, and laser power. A 2 ㎾ Nd:YAG CW laser beam has been applied to the welding of a stainless steel plate (SUS306) to investigate the welding monitoring. Theradiation signal from the weld pool was guided back through the focusing optics and the laser delivery fiber, and measured by a photo detector. By changing the focus of the laser beam along the z-direction, the penetration depth of the welding material has been measured. That shows the penetration depth depends on the frequency fluctuations of the plume signals which can be used in welding quality control.

柱現場溶接ロボット作業におけるパス間温度および入熱量の管理に関する研究

The Kobe Earthquake of January 17,1995 caused an enormous amount of damage and prompted a major revision on the design, material and construction (included in manufacturing and processing). In steel structures, many damages which lead to fatal disasters occurred at the welded joints. Accordingly welding quality of welded joints directly governs capacity of steel structure. Japanese Architectural Standard Specification JASS 6 Steel Work was revised in 1996 and interpass temperature, heat input are added to main items of welding quality control. This paper describes the best control method of interpass temperature and heat input to get satisfactory welding quality based on an experiment on interpass temperature and heat input.