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Showing papers on "Arc welding published in 2004"


Book
01 Jan 2004
TL;DR: In this paper, the process of welding is classified into three main steps: welding pool convection, oscillation, and evaporation, and welding fusion zone solidification.
Abstract: THE PROCESS AND PROCESSES OF WELDING. Introduction to the Process of Welding. Classifying Welding Processes. Fusion Welding Processes. Nonfusion Welding Processes. THE PHYSICS OF WELDING. Energy for Welding. The Flow of Heat in Welds. Thermally Induced Distortion and Residual Stresses During Welding. The Physics of Welding Energy or Power Sources. Molten Metal Transfer in Consumable Electrode Arc Welding. Weld Pool Convection, Oscillation, and Evaporation. THE CHEMISTRY OF WELDING. Molten Metal and Weld Pool Reactions. Weld Chemical Heterogeneity. THE METALLURGY OF WELDING. Weld Fusion Zone Solidification. Eutectic, Peritectic, and Postsolidification Fusion Zone Transformations. The Partially Melted Zone. The Weld Heat-Affected Zone. Weldability and Weld Testing. Closing Thoughts. Appendices. Index.

171 citations


Proceedings ArticleDOI
02 Nov 2004
TL;DR: A mixed reality system has been created for simulating gas metal arc welding (GMAW) welding, using a neural network to determine the quality and shape of the created weld based on the orientation and speed of the welding torch.
Abstract: A mixed reality system has been created for simulating gas metal arc welding (GMAW) welding. This simulation system is intended for use in training human welders. The system is comprised of a real welding torch attached to a force feedback device, a head-mounted display, a 6 DOF tracking system for both the torch and the user's head, and external audio speakers. The welding simulation is based on empirical results from detailed analysis of a series of test welds. The simulation runs in real-time, using a neural network to determine the quality and shape of the created weld based on the orientation and speed of the welding torch. The welding process and resulting weld bead are displayed in a virtual environment. Weld quality and recorded process values can be displayed after welding for review.

140 citations


Journal ArticleDOI
TL;DR: In this article, the weldability and microstructure of magnesium AZ31B alloy welded using LATIG, LBW and TIG were investigated by OM and EMPA, and the experimental results showed that the welding speed of LATIG was higher than that of TIG, which was caught up with LBW.
Abstract: Welding of AZ31B magnesium alloy was carried out using hybrid laser–TIG (LATIG) welding, laser beam welding (LBW) and gas tungsten arc (TIG) welding. The weldability and microstructure of magnesium AZ31B alloy welded using LATIG, LBW and TIG were investigated by OM and EMPA. The experimental results showed that the welding speed of LATIG was higher than that of TIG, which was caught up with LBW. Besides, the penetration of LATIG doubles that of TIG, and was four times that of LBW. In addition, arc stability was improved in hybrid of laser–TIG welding compared with using the TIG welding alone, especially at high welding speed and under low TIG current. It was found that the heat affect zone of joint was only observed in TIG welding, and the size of grains in it was evidently coarse. In fusion zone, the equiaxed grains exist, whose size was the smallest welded by LBW, and was the largest by TIG welding. It was also found that Mg concentration of the fusion zone was lower than that of the base one by EPMA in three welding processes.

122 citations


Journal ArticleDOI
TL;DR: In this article, a three-dimensional numerical heat transfer and fluid flow model was developed to examine the temperature profiles, velocity fields, weld pool shape and size, and the nature of the solidified weld bead geometry during GMA fillet welding.
Abstract: Gas metal arc (GMA) fillet welding is one of the most important processes for metal joining because of its high productivity and amiability to automation. This welding process is characterized by the complicated V-shaped joint geometry, a deformable weld pool surface, and the additions of hot metal droplets. In the present work, a three-dimensional numerical heat transfer and fluid flow model was developed to examine the temperature profiles, velocity fields, weld pool shape and size, and the nature of the solidified weld bead geometry during GMA fillet welding. The model solved the equations of conservation of mass, momentum, and energy using a boundary fitted curvilinear coordinate system. Apart from the direct transport of heat from the welding arc, additional heat from the metal droplets was modeled considering a volumetric heat source. The deformation of the weld pool surface was calculated by minimizing the total surface energy. Part I of this article is focused on the details of the numerical model such as coordinate transformation and calculation of volumetric heat source and free surface profile. An application of the model to GMA fillet welding of mild steel is described in an accompanying article (W. Zhang, C.-H. Kim and T. DebRoy, J. Appl Phys. 95, 5220 (2004)).

106 citations


Journal ArticleDOI
TL;DR: In this article, the acoustic signals generated by the gas metal arc welding (GMAW) process were measured in the surrounding air and in the parts being welded by employing a microphone and PZT sensor.
Abstract: The acoustic waves produced by the gas metal arc welding (GMAW) contain information about the behaviour of the arc column, the molten pool and droplet transfer. In this study measurements of acoustic waves generated during GMAW process were performed. Acoustic waves were measured in the surrounding air and in the parts being welded by employing a microphone and PZT sensor. To evaluate influences on sound generation extensive experiments were performed with two different unalloyed carbon steels: DIN RSt13 with 0.1% C and DIN Ck45 with 0.46% C, using two types of shielding gas: CO 2 and gas mixture by its brand name Crystal (90% Ar, 10% CO 2 ) and welding on a slope to vary the distance between welding nozzle and welding part. Acoustic signals were processed to obtain time domain and frequency domain descriptors. Some relationships between descriptors and the weld process characteristics were investigated. Results indicate that the arc sound exhibits distinct characteristics for each welding situation and that the main source of acoustic waves in short circuit metal transfer mode is arc reignition. From acoustic signals one can easily assess process stability and detect welding conditions resulting in weld defects.

100 citations


Patent
01 Sep 2004
TL;DR: In this article, a data storage medium (74) stores measured data for each electrode during the performing of the weld and a processor (110) performs a process comprising of recalling measured data corresponding to the electrode passing a reference position; and combining the recalled measured data of the plurality of spaced apart electrodes (12, 14, 16, 18) to compute a weld parameter of the tandem welding system at the reference position.
Abstract: A tandem welding system includes a plurality of spaced apart electrodes (12, 14, 16, 18) arranged to travel at a common travel speed. The plurality of spaced apart electrodes (12, 14, 16, 18) cooperatively perform a weld. A data storage medium (74) stores measured data for each electrode during the performing of the weld. A processor (110) performs a process comprising: for each electrode, recalling measured data corresponding to the electrode passing a reference position; and, combining the recalled measured data of the plurality of spaced apart electrodes (12, 14, 16, 18) to compute a weld parameter of the tandem welding system at the reference position.

90 citations


Journal ArticleDOI
TL;DR: In this paper, a new development, the Cranfield Automated Pipe-welding System (CAPS), is described, where tandem GMAW in a narrow groove has been applied to pipeline girth welding with two tandem torches in a single welding head.
Abstract: Installation of new pipelines is predicted to grow at a rapid rate over the next twenty years, due in part to the increase use worldwide of combined cycle power generation plant using natural gas a fuel. The need to construct large diameter pipelines over long distances has led to an increased demand to improve the productivity of pipeline girth welding. Many novel techniques have been tried in the past to achieve productivity gains, including laser welding, flash butt welding, homopolar welding, and radial friction welding. In spite of the failure to gain wide acceptance, there is still current development aimed at achieving their eventual implementation. Single wire mechanised gas metal arc welding (GMAW) remains the dominant pipe girth welding technique, and has been optimised in the past to produce the maximum productivity possible with this process. Continued development of GMAW with dual torch, tandem GMAW welding and novel techniques for GMAW roots is leading to further significant gains in arc welding productivity. This paper describes a new development, the CAPS project, (Cranfield Automated Pipe-welding System), where tandem GMAW in a narrow groove has been applied to pipeline girth welding with two tandem torches in a single welding head. The CAPS system offers welding productivity three to four times higher than that possible with the conventional single wire GMAW technique, while still producing a weld which is very similar to that generated by single wire welding. The development of the system is described, as well as recent successful trials under field conditions. The development of high power lasers has spurred a current high level of interest in the possibility of application to pipeline welding, and current research is described in which the feasibility of pipeline laser welding has been established.

87 citations


Journal ArticleDOI
TL;DR: The weld metal oxygen content can be significantly changed by a slight difference in the oxygen concentrations in the shielding gas in gas tungsten arc (GTA) welding process as discussed by the authors.

85 citations


Journal ArticleDOI
TL;DR: Zhang et al. as discussed by the authors used a numerical model to investigate the heat transfer and free surface flow during gas metal arc fillet welding of mild steel, and the calculated shape and size, finger penetration characteristic and solidified surface profile of the fillet welds were in fair agreement with the experimental results for various welding conditions.
Abstract: A numerical model described in part I [W. Zhang, C.-H. Kim, and T. DebRoy, J. Appl. Phys. 95, 5210 (2004)] was used to investigate the heat transfer and free surface flow during gas metal arc fillet welding of mild steel. Dimensional analysis was used to understand the importance of heat transfer by conduction and convection and the role of various driving forces on convection in the liquid weld pool. The calculated shape and size, finger penetration characteristic and solidified surface profile of the fillet welds were in fair agreement with the experimental results for various welding conditions. The calculated cooling rates were also in good agreement with independent experimental data. The effect of welding parameters on important weld bead characteristics was quantitatively studied using the numerical model. The results reported here indicate a significant promise for understanding and control of gas metal arc fillet welding processes based on fundamental principles of transport phenomena.

82 citations


Patent
23 Feb 2004
TL;DR: In this paper, an electric arc welder operated to perform a short circuit welding process between an electrode and a workpiece, where the process comprises a succession of alternate short circuit conditions and arc conditions.
Abstract: An electric arc welder operated to perform a short circuit welding process between an electrode and a workpiece, where the process comprises a succession of alternate short circuit conditions and arc conditions, with a first current waveform during the short circuit condition and a second voltage waveform during the arc condition. A first waveform generator constructs the first waveform from a series of current pulses controlled by a pulse wave modulator operated at a rate greater than 18 kHz and a second waveform generator constructs the second waveform from a series of current pulses controlled by a pulse wave modulator operated at a rate greater than 18 kHz. The second waveform generator has a circuit to generate the second waveform with a generally constant arc parameter, generally voltage.

78 citations


Journal ArticleDOI
TL;DR: In this article, cold-rolled and annealed Pd-Ag foils of thickness 50 μm have been joined by diffusion bonding in order to obtain permeator tubes used in laboratory applications for hydrogen separation and purification.
Abstract: Cold-rolled and annealed Pd-Ag 25% at. foils of thickness 50 μm have been joined by diffusion bonding in order to obtain permeator tubes used in laboratory applications for hydrogen separation and purification. The tubes produced present a sound and effective joint along the generatrix line: particularly, this procedure has shown better performance than arc welding, responsible for formation of thermally stressed zones and embrittlement of permeators.

Patent
27 Apr 2004
TL;DR: In this paper, the body of a consumable contact tip suitable for electric arc welding has been adapted to enable primary electrical contact with the electrode, and along a remainder part of the length of the bore, the body is adapted such that any secondary contact between the body and the electrode along the remainder part does not substantially short circuit the primary electric contact in the primary contact region.
Abstract: A contact tip suitable for electric arc welding has a consumable electrode. The contact tip has a body which defines a bore through which the electrode is able to pass to enable electric current from a welding power supply to be transferred from the body to the electrode. The body, in part of the length of the bore between an inlet end and an outlet end, has at least one region (herein referred to as a primary contact region) at which the body is adapted to enable primary electrical contact with the electrode, and along a remainder part of the length of the bore, the body is adapted such that any secondary contact between the body and the electrode along the remainder part does not substantially short circuit the primary electrical contact in the primary contact region of the bore.

Journal ArticleDOI
TL;DR: In this paper, the effects of electrode vapor on the behavior of a supersonic nozzle arc under dc conditions were investigated, where the arc and electrodes were treated as a coupled system and the arc plasma was assumed to be in local thermodynamic equilibrium (LTE).
Abstract: In circuit breakers, arc heaters and arc welding apparatus, metal vapor resulting from electrode erosion is inevitably injected into the arc plasma. The arc then burns in a mixture of the working gas (SF/sub 6/ in the case of circuit breakers) and electrode vapor, whose properties are substantially different from those of pure SF/sub 6/. The present work is a computational investigation into the effects of electrode vapor on the behavior of a supersonic nozzle arc under dc conditions. The arc and electrodes are treated as a coupled system. The arc plasma is assumed to be in local thermodynamic equilibrium (LTE). The thin non-LTE layer between the electrode and the arc is not included in the computation but its effects are taken into account in the energy balance at the electrode surface. A conservation equation for the electrode vapor is solved together with the governing equations for mass, momentum, and energy of the gas mixture. Comparisons were made between the results with and without electrode vaporization. Results show that vaporization of the electrode material (copper in the present investigation) has a cooling effect at the arc center and broadens the arc column. The arc voltage is, however, not sensitive to the presence of electrode vapor for the gas discharge conditions investigated.

Journal ArticleDOI
TL;DR: In this article, the effects of Ti addition on the weldability, microstructure and mechanical properties of a dissimilar weldment of Alloy 690 and SUS 304L were investigated.

Journal Article
TL;DR: In this article, resistance spot welding was used to weld aluminum alloy to steel from process development to performance evaluation, and the results showed that the alloy was more robust to steel than aluminum.
Abstract: Summary of work on resistance spot welding aluminum alloy to steel from process development to performance evaluation.

Journal ArticleDOI
TL;DR: The welding and joining of dissimilar metals which have very different properties, such as aluminium and carbon steel, is considered to be a subject for research and development in the welding/joining sector continuing into the 21st century.
Abstract: The welding and joining of dissimilar metals which have very different properties, such as aluminium and carbon steel, is considered to be a subject for research and development in the welding/joining sector continuing into the 21st century. There are also huge requirements and expectations for this sector.1 Due to the aforementioned, the research and development of welding and joining of dissimilar materials have been carried out over many years; for instance, eutectic bonding of copper pipe and aluminium pipe was developed 30 years ago and this process is still applied for the heat pipes of refrigerators. Recently it has even progressed for applications in joining of wide plate materials of aluminium alloy and stainless steel by means of the vacuum rolling process2 and also for weldments of aluminium alloy and carbon steel joined by means of friction welding and employed as automobile components.3 However, there are problems from aspects of cost and restrictions concerning the configurations fo...

Journal ArticleDOI
TL;DR: In this article, six carbon-manganese, mainly pipeline, steels were welded using both autogenous Nd:YAG laser welding, and nd: YAG laser/MAG hybrid welding.
Abstract: Lasers are capable of producing welds with deep penetration, low distortion and faster travel speeds, compared to arc welding More recently, laser/arc hybrid welding processes have also been generating interest for industrial fabrication In this paper, six carbon–manganese, mainly pipeline, steels were welded using both autogenous Nd:YAG laser welding, and Nd:YAG laser/MAG hybrid welding The improvements in weld microstructures and weld metal toughness that are possible when using the hybrid process are described and illustrated Laser/arc hybrid welding is shown to be a process that can generate good quality welds in commercially available pipeline steels It also has the potential to complete girth welds in these steels with significantly fewer welding passes than are currently required for arc welded pipelines, reducing the joint completion time

Journal Article
TL;DR: In this article, a series of hybrid welding (gas metal arc welding-CO 2 laser beam welding) experiments was conducted in which the two energy sources were cou- pled in one process zone on the surface of a 316L austenitic stainless steel work piece.
Abstract: A series of hybrid welding (gas metal arc welding-CO 2 laser beam welding) experiments was conducted in which the two energy sources were cou- pled in one process zone on the surface of a 316L austenitic stainless steel work- piece. Arc and laser power were varied in order to study their influence on various bead dimensions. Arc power and, conse- quently, the mode of metal transfer have a great influence on bead width W, arc and laser penetration M and L, and bead rein- forcement R. Increasing arc power in- creases W and L, whereas it reduces M and R. Laser power and hence the laser- induced metal vapor significantly influ- ences the features of the metal transfer mode in the arc process. Higher laser pow- ers prolong the arc burning time T a at the expense of the short circuit frequency Nsc , which assists in increasing M and L. At constant laser power, the contribution of the M solely into the total penetration M + L is always bigger than that of the L. interaction between the two energy sources is optimized. The arc welding process, characterized by relatively lower power density and wider process zone, gives a wide bead, thus enhancing the joint's root bridging ability and enlarging the manufacturing tolerances for joint preparation. Simultaneously, the laser beam process, characterized by higher lo- calized power density, leads to a deeper penetration. Thus in hybrid GMA-laser beam welding, a wide and deep bead is achieved at higher welding speeds when compared with the GMAW process by its own (Ref. 8). This accordingly leads to less heat input per unit length, less thermal distortion, and therefore, less residual stresses, narrower heat-affected zone (HAZ), and more important, increased

Journal ArticleDOI
TL;DR: In this paper, a neural network model was developed to predict the weld bead width as a function of key process parameters in robotic gas metal arc (GMA) welding, which is a manufacturing process which is used to produce high quality joints and has to a capability to be utilized in automation systems to enhance productivity.
Abstract: Robotic gas metal arc (GMA) welding is a manufacturing process which is used to produce high quality joints and has to a capability to be utilized in automation systems to enhance productivity. Despite its widespread use in the various manufacturing industries, the full automation of the robotic GMA welding has not yet been achieved partly because mathematical models for the process parameters for a given welding tasks are not fully understood and quantified. In this research, an attempt has been made to develop a neural network model to predict the weld bead width as a function of key process parameters in robotic GMA welding. The neural network model is developed using two different training algorithms; the error back-propagation algorithm and the Levenberg–Marquardt approximation algorithm. The accuracy of the neural network models developed in this study has been tested by comparing the simulated data obtained from the neural network model with that obtained from the actual robotic welding experiments. The result shows that the Levenberg–Marquardt approximation algorithm is the preferred method, as this algorithm reduces the root of the mean sum of squared (RMS) error to a significantly small value.

Journal ArticleDOI
04 May 2004
TL;DR: In this article, anode melting was predicted for free-burning arcs by making two-dimensional calculations of temperature profiles of the arc and the electrodes to make predictions of weld depth and weld shape in arc welding.
Abstract: Predictions have been made of anode melting for free-burning arcs by making two-dimensional calculations of temperature profiles of the arc and the electrodes to make predictions of weld depth and weld shape in arc welding. Predicted properties at 150 A, for various arc lengths, are compared with experimental results of: 1) weld shape; 2) heat intensity as a function of radius; and 3) current density as a function of radius at the anode. The whole region of the arc system is modeled, including the tungsten cathode, the arc plasma and the solid and molten anode, including convection within the molten weld-pool. Theoretical and experimental results are also obtained for highand low-sulfur steel, which have markedly different surface tension properties of the molten liquid, resulting in weld depths that differ by a factor of three because of changed convective circulation properties in the weld pool. Although total power to the anode increases with increasing electrode separation, the current density becomes less, with the result that for electrode distances above 2 mm, for argon, the width and depth of the molten region become less, in agreement with experimental results that we have obtained.

Patent
18 Mar 2004
TL;DR: In this paper, a method of welding titanium and titanium-based alloys to ferrous metals (200) is described, where supplementary filler material (400) is provided to alter the proportions of various elements in the weld pool.
Abstract: A method of welding titanium, and titanium based alloys, (100) to ferrous metals (200) is described. Welding of titanium, and titanium based alloys, (100) is plagued with poor quality and highly brittle welds, substantially due to formation of Ti-Fe intermetallics in the weld pool (600). The instant invention provides supplementary filler material (400) to alter the proportions of various elements in the weld pool (600). Certain fillers (400), such as nickel or iron, added to the weld pool (600) enable high quality welds to be fabricated utilizing a wide variety of fusion welding techniques, including laser welding, between titanium, or titanium based alloys, (100) and ferrous metals (200), including but not limited to the welding of nickel-titanium and stainless steel. Filler material (400) may be supplied in various forms, including foil (410), wire (110) (210), powders, preformed gaskets, and others. Optionally, the titanium or titanium based alloy (100) may be stress relieved to achieve full recovery of the shape memory strain prior to welding.

01 Jan 2004
TL;DR: A thorough derivation of the electromagnetic force is included in the thesis, and an arc length minimization algorithm is proposed for enhancing the ability to focus the arc, and also, to minimize the heat input into the workpiece.
Abstract: In this thesis the objective is to optimize the control algorithms for the manual pulsed Gas Metal Arc Welding (GMAW) process, with the aim of enhancing the quality of welded joints. To be able to develop controllers for the GMAW process, and also for enabling process simulation, a mathematical model describing the GMAW process is developed. The mathematical model includes a description of the electrical circuit, the drop dynamics, and the melting rate, and also, the model includes criteria for drop detachments. Basically, the electrical circuit consists of the welding machine, the wires, the electrode, and the electrical arc. The drop is modelled as a mass-spring-damper system influenced by a number of external forces. Of these external forces the electromagnetic force is the most significant. Due to the importance of the electromagnetic force, a thorough derivation of the electromagnetic force is included in the thesis. The melting rate of the consumable electrode is modelled both from a statically (steady-state) point of view, and from a dynamically point of view. The static model is a simple equation describing the melting rate, while the dynamic model is more complex. The structure of GMAW control is discussed, and based on this discussion a general control structure is presented. This structure includes an arc length controller and a metal transfer controller, and also, an inner loop controlling the welding current. The current is assumed to be controlled by a traditional PI-controller, and therefore, this inner control loop is not considered in the thesis. For arc length control, a nonlinear controller based on feedback linearization is proposed, and robustness and performance are considered. For metal transfer control an approach based on obtaining a uniform drop size prior to pulse initiation is proposed. This is carried out by calculating the amount of melted electrode between the current pulses during the welding process. The purpose of the uniform drop size approach is to enhance the robustness of the drop detachment process. In addition to the arc length controller and the metal transfer controller, an arc length minimization algorithm is proposed for enhancing the ability to focus the arc, and also, to minimize the heat input into the workpiece. Simulation programs for testing the controllers and algorithms have been developed, and successful tests have been carried out.

Journal ArticleDOI
TL;DR: Closed-loop control experiments have verified the effectiveness of the developed system as a robust control which requires no re-adjustment and can function properly when fluctuations/variations in manufacturing conditions, and thus the process dynamics, change, vary, or fluctuate.

Journal ArticleDOI
TL;DR: In this paper, the development of an optical inspection system for monitoring the manual gas tungsten arc welding (GTAW) process of steel pipes is described, where the arc plasma visible emission produced during the process was acquired and spectroscopically analyzed.
Abstract: Non-intrusive and real-time monitoring techniques are increasingly required by manufacturing industry in order to detect flaws in arc welding processes. In this work the development of an optical inspection system, for monitoring the manual gas tungsten arc welding (GTAW) process of steel pipes, is described. The arc plasma visible emission produced during the process was acquired and spectroscopically analysed. Measuring the intensities of selected argon emission lines allowed real time calculation and recording of the axial electron temperature of the plasma. Experimental results showed that the temperature signal varies greatly in the case of instabilities of the weld pool that cause weld defects. A suitable algorithm, based on a statistical analysis of the signal, was developed in order to real time flag defective joints. It is shown that several weld defects such as porosity, dropout, lack of fusion, solid inclusions and craters were successfully detected in a production environment. The performances of the optical sensor were compared with the results of state-of-the-art post-weld controls such as x-rays and penetrating dyes, showing good agreement and thus demonstrating the validity of this quality monitoring system.

Proceedings ArticleDOI
22 Aug 2004
TL;DR: A novel hybrid visual servo control method for arc welding robot is provided, in which the position-based and image-based visual Servo method are integrated to increase the robustness of weld seam tracking.
Abstract: The methods to improve the robustness and adaptability of arc welding robots are presented. Image processing algorithm for feature extraction from structured light images of weld seam is discussed in the case of a large amount of strong reflection, arc light and splash disturbance. The processes consist of defining target region, selecting adaptive threshold and extracting feature points. Then a novel hybrid visual servo control method for arc welding robot is provided, in which the position-based and image-based visual servo method are integrated to increase the robustness of weld seam tracking. The welding experiment is well conducted to verify the methods

Patent
02 Jul 2004
TL;DR: In this article, a welding torch for an arc welding robot comprises an acceleration sensor which is disposed inside the welding torch and provided on each axis so as to detect shocks received when the welding torches are brought into contact with a structure to be welded as the vibration acceleration in three axial directions orthogonal to each other.
Abstract: PROBLEM TO BE SOLVED: To provide a welding torch having a compact shock detection circuit of high detection sensitivity of collision. SOLUTION: A welding torch for an arc welding robot comprises an acceleration sensor which is disposed inside the welding torch and provided on each axis so as to detect shocks received when the welding torch is brought into contact with a structure to be welded as the vibration acceleration in three axial directions orthogonal to each other, and a contact detection means 102 which is connected to the acceleration sensor on each axis and outputs the pulse signal when the detection signal of the acceleration sensor exceeds the threshold for the reference, and further comprises a signal processing circuit 101 comprising a first AND circuit to convert the signal output from the contact detection means of each axis into the contact signal, and a shock detection circuit 14 built therein to stop the robot after the contact detection signal output from the signal processing circuit is transmitted to a robot controller 15. COPYRIGHT: (C)2004,JPO&NCIPI

Patent
06 Oct 2004
TL;DR: In this paper, a method of arc welding with a cored electrode comprising creating a positive waveform with a first shape and having a first time, creating a negative waveform and having another time, adjusting the percentage relationship of the first and second times so the time of the shape with the greater magnitude is substantially less than the other shape.
Abstract: A method of arc welding with a cored electrode comprising creating a positive waveform with a first shape and having a first time; creating a negative waveform with a second shape and having a second time; making one of the first and second shapes greater in magnitude than the other of the shapes; and, adjusting the percentage relationship of the first and second times so the time of the shape with the greater magnitude is substantially less than the time of the other shape.

Patent
26 Mar 2004
TL;DR: In this paper, a method and apparatus for multi-process welding includes providing a controlled short circuit output and a pulse output in response to user selection across a workpiece output stud and a torch output stud.
Abstract: A method and apparatus for multi process welding includes providing a controlled short circuit output and a pulse output in response to a user selection across a workpiece output stud and a torch output stud.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the factors which affect the fatigue strength of the welded commercial magnesium alloy joints as welded surface, and the welding processes used in this investigation were TIG and FSW.
Abstract: Magnesium alloys have attracted special attention of researchers working in transportation industries because they are the best lightweight structural materials with a relatively high-strength to weight ratio and excellent technological properties. Enhancement of structural application of such a structural material depends on the ability of construction by welding. The welding of magnesium alloys has been investigated widely. Results indicate that FSW (friction stir welding) and TIG (tungsten inert gas arc welding) are successful welding methods for magnesium alloys and aluminum alloys. 1–4) Reliability is their salient attribute, especially for use in the transportation industry. Therefore, the clarification of fatigue properties must precede application of joining by welding. 5) This study investigated the factors which affect the fatigue strength of the welded commercial magnesium alloy joints as welded surface. Investigated alloys were extruded or rolled AZ31 and AZ61. The welding processes used in this investigation were TIG and FSW. Joint efficiencies (%)

Journal ArticleDOI
TL;DR: In this article, the authors investigated the residual stress distribution in the weld joint of HQ130 grade high strength steel by means of finite element method (FEM) using ANSYS software.
Abstract: The distribution of the residual stress in the weld joint of HQ130 grade high strength steel was investigated by means of finite element method (FEM) using ANSYS software. Welding was carried out using gas shielded arc welding with a heat input of 16 kJ/cm. The FEM analysis on the weld joint reveals that there is a stress gradient around the fusion zone of weld joint. The instantaneous residual stress on the weld surface goes up to 800 ∼ 1000 MPa and it is 500 ∼ 600 MPa, below the weld. The stress gradient near the fusion zone is higher than any other location in the surrounding area. This is attributed as one of the significant reasons for the development of cold cracks at the fusion zone in the high strength steel. In order to avoid such welding cracks, the thermal stress in the weld joint has to be minimized by controlling the weld heat input.