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About this book

The primary aim of this volume is to provide researchers and engineers from both academia and industry with up-to-date coverage of recent advances in the fields of robotic welding, intelligent systems and automation. It gathers selected papers from the 2017 International Workshop on Intelligentized Welding Manufacturing (IWIWM’2017), held June 23-26, 2017 in Shanghai, China. The contributions reveal how intelligentized welding manufacturing (IWM) is becoming an inescapable trend, just as intelligentized robotic welding is becoming a key technology. The volume is divided into four main parts: Intelligent Techniques for Robotic Welding, Sensing in Arc Welding Processing, Modeling and Intelligent Control of Welding Processing, and Intelligent Control and its Applications in Engineering.

Table of Contents

Frontmatter

Feature Articles

Frontmatter

Arc Welding Processes for Additive Manufacturing: A Review

Arc-welding based additive manufacturing techniques are attracting interest from the manufacturing industry because of their potential to fabricate large metal components with low cost and short production lead time. This paper introduces wire arc additive manufacturing (WAAM) techniques, reviews mechanical properties of additively manufactured metallic components, summarises the development in process planning, sensing and control of WAAM, and finally provides recommendations for future work. Research indicates that the mechanical properties of additively manufactured materials, such as titanium alloy, are comparable to cast or wrought material. It has also been found that twin-wire WAAM has the capability to fabricate intermetallic alloys and functional graded materials. The paper concludes that WAAM is a promising alternative to traditional subtractive manufacturing for fabricating large expensive metal components. On the basis of current trends, the future outlook will include automated process planning, monitoring, and control for WAAM process.
Zengxi Pan, Donghong Ding, Bintao Wu, Dominic Cuiuri, Huijun Li, John Norrish

Research Papers

Frontmatter

Study on Human Welder Behavior by Measuring Local Flow Pattern of Weld Pool and Torch Posture

To study human welder behavior by sensing the welding torch posture and weld pool flow pattern, so as to provide a way to realize intelligent robot welding, a synchronous experiment system is setup with laser vision and a dynamic tilt sensor to precisely obtain the three-dimensional information of weld pool and torch posture. In the downward welding experiment, the data of reflected laser striped image of weld metal fluid flow and the change of torch posture are obtained. The algorithm for extracting weld metal fluid flow characteristic parameters is also written to obtain the weld pool flow pattern. Through the experiment analysis, it is found that the change of weld pool flow characteristic parameters and the change of torch posture have obvious coherence. The change of torch posture reflects the reaction and control ability of the human welder. The change of the weld pool flow characteristic parameters reflects that the welder maintains specific weld metal fluid flow pattern and obtains good weld forming ability.
Ding Fan, Xiaochun Dun, Gang Zhang, Yu Shi

A Robotic Re-manufacturing System for High-Value Aerospace Repair and Overhaul

This paper describes the necessary elements for the development of a bespoke robotic welding system for aerospace turbofan compressor blade re-manufacturing. The established industry-academia research partnership and project evolution at The University of Sheffield (UK) from 2006 is highlighted in the joint development of a disruptive platform technology for high-value aerospace re-manufacturing. The design process, funding mechanisms, research and development of key components (vision system, high-speed DAQ, advanced GTAW welding system trials) are described in this paper. Interaction of these key components when combined with novel collaborative robotic technology and experienced welding engineers has made this project possible. This industry-academia research intensive collaboration between VBC Instrument Engineering Limited (UK) and The University of Sheffield has received project funding from the Engineering and Physical Sciences Research Council (EPSRC, 2006–2010), the Science and Facilities Technology Council (STFC, 2011–2013) and Innovate-UK with the Aerospace Technology Institute (2014–2018).
Richard French, Hector Marin-Reyes, Andrew Rendell-Read

Automated Programming for Robotic Welding

Robotic welding automation allows manufacturers to increase quality, flexibility and reduce costs. However, the costs involved in programming welding robots for small production runs limits viability for Small and Medium Enterprises to employ arc welding automation. This paper outlines an Automated Offline Programming framework which can be used to generate robot programs directly from Computer Aided Design models with minimal human input, allowing programming costs to be drastically reduced or even eliminated. The key stages of our approach are presented and a specific implementation for welding of complex pipe structures is shown. The results demonstrate the feasibility of our method to enable truly flexible robotic welding automation.
Nathan Larkin, Andrew Short, Zengxi Pan, Stephen van Duin

Investigation of the Correlation Between Plasma Electron Temperature and Quality of Laser Additive Manufacturing Process

In this paper, a spectral diagnosis method was reported to explore the temperature characteristic of plasma and detect the forming quality in laser additive manufacturing. The spectral data were collected by the spectrum acquisition system under different processing parameters. The plasma temperatures under different processing conditions were calculated using Boltzmann plot of six neutral iron lines between 375 nm and 390 nm, and the influence relationships between laser power, powder feeding rate, traverse speed, cladding layer and plasma temperature were found. Meanwhile, the time domain diagrams (the relationship between the temperature and time) corresponding to the process were established, in which temperatures were respectively calculated by Boltzmann double-line method and Boltzmann plot method, to analyze the correlation between temperature fluctuation and the forming defects. It was found that the results from Boltzmann plot method could reflect the generated defects more clearly.
Bo Chen, Yongzhen Yao, Caiwang Tan, Yuhua Huang, Xiaoguo Song, Jicai Feng

Welding Technology Analysis of Bypass Coupling Micro Plasma Welding

The method of bypass coupling micro plasma welding was introduced, and used for the research of surfacing welding experiment. Different welding parameters were investigated, the thermal cycling curves were test, and the microstructure was observed. The result shows, with the increase of bypass current, the highest temperature of thermal cycling curves decreased and the microstructure was much fine. Therefore, we could speculate that the heat input to base metal is decreasing with the increase of bypass current. The bypass coupling micro plasma welding can achieve the accurate control of arc heat, balance the heat input to base metal and welding wire. Compared with traditional micro plasma welding, bypass coupling micro plasma welding can accurately control the heat input to base metal under the condition of constant heat input.
Jiankang Huang, Jing He, Ting Li, Shurong Yu, Yu Shi, Ding Fan

Online Control of Deposited Geometry of Multi-layer Multi-bead Structure for Wire and Arc Additive Manufacturing

A robotic wire and arc additive manufacturing (WAAM) system with active vision sensing capability was implemented to improve the geometry accuracy of multi-layer multi-bead structures. Width and height of the deposited bead were online detected and the accuracies of the designed sensing approaches are 0.25 mm and 0.1 mm, respectively. A double-input-double-output controller with two subsystems was designed to ensure the uniformity of bead width and bead height. The bead width was adjusted by a single neuron self-learning PI controller, while the bead height was controlled based on a rule-based engine. The experimental results indicated that (i) accuracy of the deposited bead width is controlled in 0.5 mm, (ii) accumulation effect of the bead height deviations has disappeared when multiple layers are overlapped, and (iii) the surface finish of each layer was controlled to be flat as well.
Qinglin Han, Yongzhe Li, Guangjun Zhang

The Research on Welding Sources and Ni Interlayer Synergy Regulation in Laser-Arc Hybrid Welding of Mg and Al Joints

Mg and Al alloys were joined by a laser-arc hybrid welding method with addition of Ni interlayer. The macrostructure and elements distributions of the joints were observed by the SEM and EPMA, and the plasma forms of the laser-arc hybrid welding sources were analyzed by the high speed camera. The results showed that the welding mode in Al fusion zone changed from conductive mode to keyhole mode, the intermetallic in the Al fusion zone increased obviously, which still influence the property of the joints evident. The effect of the laser induced arc was changed with the varying of laser and arc welding parameters, which made influence on the welding mode and reactions in the welding process. The regulation of the hybrid welding sources between the elements reactions was an important factor for the joining of dissimilar metals.
Hongyang Wang, Gang Song, Baoqiang Feng, Liming Liu

Effects of Laser Welding Parameters on the Characteristics of Deposition Layer

Laser welding with filler wire makes welding more cost efficient due to its properties. However, fluctuation of welding parameters seriously affects the stability of welding process and the quality of deposition layer. Based on the high speed camera system and welding process test, this paper focuses on effects of welding parameters on the laser-wire coupling behavior, the transition behavior of molten metal and the characteristics of deposition layer. The results showed that the transition behaviors of liquid metal were decomposed into globular transition behavior, liquid-bridge transition behavior and spreading transition behavior, among which the liquid-bridge transition behavior was most stable relatively. Different dynamic welding processes in different circumstances were established to interpret the laser-wire coupling behaviors and the transition behaviors of liquid metal while the D was zero. It was found that the coupling behavior and the transition behavior of liquid metal belonged to different dynamic process with the variable welding parameters. The optimized welding parameters were obtained by analyzing the stability of welding process and the characteristics of deposition layer.
Guoxing Su, Yu Shi, Gang Zhang, Jinlong Xie

Measurement of the Dynamic and Liquid Weld Pool Under Glaring Arc Light with Femtometre Accuracy

Accurate measurement of the 3D shape of the dynamic weld pool is of great importance for on-line welding process control and off-line welding phenomenon study. However, it remains challenging due to the following reasons. Firstly, the weld pool is dynamic and liquid with extremely high temperature, which requires a nondestructive single-shot measurement technique. Secondly, the specular surface and the ambient strong arc light prevent direct imaging by cameras. Here, we present a structured light technique that yields closed form solutions with femtometre accuracy to measure the dynamic shape of the weld pool produced by gas tungsten arc welding (GTAW). This technique makes use of the band-pass filter and the high penetrability of lasers to overcome the glaring arc light. The sampling points on the weld pool surface are measured by computing the intersections of the projected laser rays and the corresponding reflected laser rays analytically. A conformal mapping transforms the physical world into the virtual world to make the measurement free of optics aberrations. As a result, the achieved measurement accuracy is up to 10−13 mm, which is significantly superior to state of art methods.
Zhenzhou Wang, Yongming Yang

Study on Microstructure and Mechanical Properties of Ti6Al4V Titanium Alloy Joint with Ultrasonic Consolidation

Lap joint test of the Ti6Al4V titanium alloy with 0.3 mm thickness was conducted by ultrasonic consolidation. The effects of different consolidation time on welded joint microstructure and mechanical properties were studied by optical microscopy(OM), energy dispersive spectrometer (EDS), universal testing machine and other analytical methods. The results showed that the; Mechanical embedment which occurred at the primary stages of ultrasonic consolidation would disappear with the consolidation time increased; dislocation diffusion is the main diffusion way of interfacial atoms, the diffusion of gap and vacancy are less affected. The influence of pretreatment of the oxide film on the tensile shear strength reduced with the increase of welding time. The maximum shear force of the joint is 1940 N, the interface hardness reaches the maximum value when the welding pressure is 0.5 MPa and the welding time is 125 ms.
Zhengqiang Zhu, Mingfeng Li, Zhanzhan Su, Deqin Zhang, Yifu Zhang

Finite Element Analysis of GTAW Welding Arc Based on Rotational Arc Sensor

A three-dimensional mathematical model of rotational gas tungsten arc welding (GTAW) was established according to magnetohydrodynamics (MHD) theory, the welding arc of conventional GTAW and rotational GTAW were simulated by FLUENT to get the arc plasma’s temperature field, velocity field and the static pressure field. The results show that the centrifugal force has little influence on the arc plasma because it’s far weaker than the electromagnetic force, and the arc shape as well as physical quantity distribution of these two kinds of welding methods are essentially consistent.
Jianping Jia, Xin Wang, Shuhao Jia, Jigang Liu, Shixiong Ai

Short Papers and Technical Notes

Frontmatter

Analysis of Spreading of the Melt in Diode Laser-TIG Hybrid Cladding Process

A diode laser-TIG hybrid cladding process was proposed in this study to make further improvement on wettability and spreadability of cladding layer. Cladding layers fabricated with different heat sources were wire-cutted to observe their cross section so as to characterize the wettability. The role of TIG arc in this process is analyzed and illustrated in detail through the cladding process recorded by a high-speed camera. The functions of TIG arc in this process are elevating thermal input to reduce surface tension and exerting extra forces on the melt to help it spread out.
Xubin Li, Yu Shi, Ming Zhu, Xiaochun Yao

Numerical Simulation of Droplet Transfer of AZ31B Magnesium Alloy Based on FLUENT

According to electromagnetic theory and fluid dynamics theory, the AZ31B magnesium alloy GMAW droplet transfer was simulated in the paper, by VOF model of FLUENT software to track the free interface of gas-liquid, use UDF order to add source term of momentum and energy equation. The simulation results show that when welding current is 100 A, the type of transfer belongs to globular transfer, and the type of droplet transfer of 280 A belongs to projected transfer; the critical transition current from globular transfer to projected transfer is about 220 A. With the increase of welding current, the diameter and length of droplet become small, the ratio of long axis length to the short axis length become more and more small, and the shape of droplet changes from long-oval to round. The neck part produces the maximum pressure, maximum pressure coefficient, maximum droplet velocity; the temperature gradient increases along with the axial direction; those factors will accelerate formation of the pencil tip and promote the droplet transfer.
Guohong Ma, Xu Shen, Xiaofei Peng, Peng Chen, Xiaoling Zhu

Research of Maintenance Manipulator in Remote Handling System for Small Openings

Remote handling maintenance system, especially in the cavity with small openings and complex inner geometry, has been regarded as the key issue on the maintenance for the Magnetic Confinement Fusion (MCF). The maintenance system presented here is specially researched for Tokamak of ITER that need to be monitored to guarantee working well and safely. Due to neutron activation, the repair, inspection or maintenance of in-vessel components of Tokamak has to be carried out remotely. With the increasing demand of communication bandwidth, response speed and real-time of open control system for multi-DOFs manipulator and considering the current system’s shortage in real-time and stability, this paper presents the control system of 12-DOFs maintenance manipulator in remote handling system. The system based on the EtherCAT network performances well in real time with sufficient stability.
Kai Gu, Qixin Cao

Backmatter

Additional information