To see the other types of publications on this topic, follow the link: Gas welding.
Dissertations / Theses on the topic 'Gas welding'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Gas welding.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Segar, Richard William Moore. "Activated tungsten inert gas welding." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621314.
Full text
2
Erener, Yavuz. "Analysis Of Welding Parameters In Gas Metal Arc Welding By A Welding Robot." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607766/index.pdf.
Full textAbstract:
ANALYSIS OF WELDING PARAMETERS IN GAS METAL ARC
WELDING BY A WELDING ROBOT
Erener, Yavuz
M.S., Department of Mechanical Engineering
Supervisor : Prof. Dr. R. Tuna Balkan
Co-Supervisor : Prof. Dr. M. A. Sahir Arikan
September 2006, 130 pages
In Robotic Gas Metal Arc Welding process, the welding parameters controlled by the welder (travel speed of the welding torch, wire feed speed, current, voltage, wire diameter, etc.) should be considered to obtain a desired welding quality. To design an appropriate welding model for the used equipment, the effects of each parameter should be studied by carrying out an adequate number of experiments. The welding process is described by analyzing the experimental data to define the relationships between the welding parameters and process variables. Various regressional models can be suggested to establish the analytical relationships.
In this study, the relationship between bead geometry and voltage, current, travel speed and wire feed speed is established by using a specific computer program developed for this purpose.
3
Goodarzi, Massoud. "Mathematical modelling of gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) processes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27936.pdf.
Full text
4
Liratzis, Theocharis. "Tandem gas metal arc pipeline welding." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/5686.
Full textAbstract:
Energy consumption has grown by 2% per year worldwide over the past ten years. In 2005 worldwide 900,000 barrels of oil and 7.6 billion cubic metre of natural gas were produced daily. The exploitation of fields to meet the increased demands in energy requires the presence of adequate infrastructures. High strength pipeline steels(X100) have been developed to operate at higher pressures allowing a greater volume of fuel to be transported. Additional advantages arising from the reduction in wall thickness contribute to reduction in construction costs and steel volume.
5
Talkington, John Eric. "Variable polarity gas metal arc welding." Connect to resource, 1998. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1130352747.
Full textAbstract:
Thesis (M.S.)--Ohio State University, 1998.Advisor: Richard W. Richardson, Welding Engineering Program. Includes bibliographical references (leaves 111-113). Available online via OhioLINK's ETD Center
6
Kim, Yong-Seog. "Metal transfer in gas metal arc welding." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14199.
Full text
7
Modenesi, P. J. "Statistical modelling of the narrow gap gas metal arc welding process." Thesis, Cranfield University, 1990. http://dspace.lib.cranfield.ac.uk/handle/1826/831.
Full textAbstract:
The J-laying technique for the construction of offshore pipelines requires a fast welding process that can produce sound welds in the horizontal-vertical position. The suitability of narrow gap gas metal arc welding (NG-GMA W) process for this application was previously demonstrated. The present programme studied the influence of process parameters on the fusion characteristics of NG-GMA welding in a range of different shielding gas compositions and welding positions. Statistical techniques were employed for both designing the experimental programme and to process the data generated. A partial factorial design scheme was used to investigate the influence of input variables and their interaction in determining weld bead shape. Modelling equations were developed by multiple linear regression to represent different characteristics of the weld bead. Transformation of the response variable based on the Cox-Box method was commonly used to simplify the model format. Modelling results were analysed by graphical techniques including surface plots and a multiplot approach was developed in order to graphically assess the influence of up to four input variables on the bead shape. Conditions for acceptable bead formation were determined and the process sensitivity to minor changes in input parameters assessed. Asymmetrical base metal fusion in horizontalvertical welding is discussed and techniques to improve fusion presented. At the same time, the interaction between the power supply output characteristic and the bead geometry was studied for narrow gap joints and the effect of shielding gas composition on both process stability and fusion of the base metal was assessed. An arc instability mode that is strongly influenced by arc length, power supply characteristic and shielding gas composition was demonstrated and its properties investigated. An optimized shielding gas composition for narrow gap process was suggested.
8
Jones, Lawrence Anthony. "Dynamic electrode forces in gas metal arc welding." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11287.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (p. 306-313).
by Lawrence Anthony Jones.
Ph.D.
9
Sen, Debamoy. "Coupled Field Modeling of Gas Tungsten Arc Welding." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/38820.
Full textAbstract:
Welding is used extensively in aerospace, automotive, chemical, manufacturing, electronic and power-generation industries. Thermally-induced residual stresses due to welding can significantly impair the performance and reliability of welded structures. Numerical simulation of weld pool dynamics is important as experimental measurements of velocities and temperature profiles are difficult due to the small size of the weld pool and the presence of the arc. From a structural integrity perspective of welded structures, it is necessary to have an accurate spatial and temporal thermal distribution in the welded structure before stress analysis is performed. Existing research on weld pool dynamics simulation has ignored the effect of fluid flow in the weld pool on the temperature field of the welded joint. Previous research has established that the weld pool depth/width (D/W) ratio and Heat Affected Zone (HAZ) are significantly altered by the weld pool dynamics. Hence, for a more accurate estimation of the thermally-induced stresses it is desired to incorporate the weld pool dynamics into the analysis. Moreover, the effects of microstructure evolution in the HAZ on the mechanical behavior of the structure need to be included in the analysis for better mechanical response prediction. In this study, a three-dimensional model for the thermo-mechanical analysis of Gas Tungsten Arc (GTA) welding of thin stainless steel butt-joint plates has been developed. The model incorporates the effects of thermal energy redistribution through weld pool dynamics into the structural behavior calculations. Through material modeling the effects of microstructure change/phase transformation are indirectly included in the model. The developed weld pool dynamics model includes the effects of current, arc length, and electrode angle on the heat flux and current density distributions. All the major weld pool driving forces are included, namely surface tension gradient, plasma drag force, electromagnetic force, and buoyancy. The weld D/W predictions are validated with experimental results. They agree well. The effects of welding parameters (like welding speed, current, arc length, etc.) on the weld D/W ratio are documented. The workpiece deformation and stress distributions are also highlighted. The transverse and longitudinal residual stress distribution plots across the weld bead and their variations with welding speed and current are also provided. The mathematical framework developed here serves as a robust tool for better prediction of weld D/W ratio and thermally-induced stress evolution and distribution in a welded structure by coupling the different fields in a welding process.Ph. D.
10
Campbell, Stuart William. "Shielding gas parameter optimisation in arc welding processes." Thesis, University of Strathclyde, 2015. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25988.
Full textAbstract:
This thesis is focussed on shielding gas optimisation in gas shielded arc welding processes, and has been conducted along two themes; deriving conditions in which the shielding gas flow rate can be safely reduced, and through the highly novel process of alternating shielding gases. The correct shielding gas flow rate is essential for providing adequate protection to the weld metal during the heating, liquid and solidification stages. Hence, there is an optimum shielding gas flow rate, but this is difficult to define and is often decided on the basis of preference or experience. A multi-disciplined, systematic study has been conducted, which has shown that there is considerable scope to reduce the shielding gas flow rate. Experimental trials have shown that the shielding gas flow rate can be reduced, in a draft-free environment, to 6 l/min, with no degradation in weld quality for the worst draft conditions measured in a typical shipyard fabrication hall, at 10 l/min. This study has resulted in shielding gas flow controllers, preset at 12 l/min, being installed in a large shipyard environment, removing the welding operatives ability to increase the shielding gas flow rate. The application of alternating shielding gases offers clear manufacturing cost reduction benefits which arise from measurable increases in productivity, improved distortion control and re-work reduction, and overall improvements to the mechanical properties of the weld. Arc pressure measurements, and the subsequent derivation of forces acting on the liquid weld metal, have indicated that flow vectors for helium are opposite in direction to that produced by argon, creating a dynamic action within the weld pool. Schlieren visualisation has shown that there is a greater degree of helium entrainment in the primary jet due to a constriction of its flow in the secondary jet, influencing the arc's behaviour and inferring more of the associated benefits.
11
Shen, Hao. "Seam position detection in pulsed gas metal arc welding." Access electronically, 2003. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20040823.125740/index.html.
Full text
12
Ludick, Mark. "Experimental sensitivity analysis of welding parameters during transition from globular to spray metal transfer in gas metal arc welding." Thesis, Peninsula Technikon, 2001. http://hdl.handle.net/20.500.11838/1269.
Full textAbstract:
Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, Cape Town, 2001Since the discovery of arc welding at the beginning ofthe century, metal transfer has been a topic ofresearch interest. Metal transfer can, in fact be related to weld quality, because it affects the arc stability. Furthermore, it determines the weld spatter, penetration, deposition rate and welding position. Gas Metal Arc Welding (also known as Metal Inert Gas- or MIG welding) is the most co=on method for arc welding steels and aluminurn alloys. Approximately 40% of the production welding in the country is accomplished by this process in which the thermal phenomena and melting ofthe solid electrode are coupled to the plasma arc and the weld pool. Thus the therrno- fluid behaviour of the electrode and detaching drops can have significant effects on the subsequent weld quality and production rate. The knowledge of how metal transfer affects this arc welding process is important for welding control and process automation, as well as in the development of improved welding consumables. Gas metal arc welding has a distinct feature, indicated by the results of Lesnewich [24], [23], that for most gases, there is a discrete metal droplet formation change between low and high current operations. Naturally the droplet size will have a significant influence on the properties ofthe welds. In globular transfer which occurs at low current, the welding electrode melts and produces large droplets (usually larger in diameter than the electrode wire diameter). This mode of transfer is associated with high spatter levels and thus undesirable in terms of welding economics. An increase in welding current will, for most welding! shielding gases, produce metal transfer with smaller droplets, which is termed spray transfer. This mode oftransfer is associated with high voltage and amperage settings, thus producing high deposition rates limited to the flaUhorizontal position.
13
Hansen, James Christopher. "Rotating Electrode Pulse Gas Metal Arc Welding for Improved Aluminum Shipbuilding Quality." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1606991932450895.
Full text
14
Liu, Xiaopei. "Dual Bypass Gas Metal Arc Welding Process and Control." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_diss/664.
Full textAbstract:
GMAW (Gas Metal Arc Welding) is one of the most important arc welding processes being adopted in modern manufacturing industry due to its advantages in productivity, energy efficiency and automation. By monitoring and improving some of the important properties of GMAW such as production rate, metal transfer and base metal heat input, researchers could bring the process efficiency and stability to a new level. In recent years, some innovative modifications of GMAW such as Twins, Tandem and laser-MIG hybrid welding have been adopted into many industrial applications for better productivity.
In this dissertation, a novel GMAW called DB-GMAW (Dual Bypass Gas Metal Arc Welding) using two GTAW torches and one GMAW torch to construct a welding system, is proposed and developed. In DB-GMAW, two GTAW torches perform the bypass system which decouples the total welding current into base metal current and bypass current after the melt down of filler wire. Compared to conventional GMAW, DB-GMAW has many advantages in droplet formation, base metal heat input and penetration achievement due to its unique characteristics in welding arc and current flow. In the first place of the research, experimental system of DB-GMAW is constructed. Then, sufficient experiments under different parameters are performed to provide us a good understanding of the behaviors and characteristics of this novel GMAW process. Observation about metal transfer formation and base metal heat input is studied to verify its theoretical analysis. Full penetration of work piece via DB-GMAW is achieved based on a series of parameter testing experiments. Moreover, image processing techniques are applied to DB-GMAW to monitor the welding process and construct a feedback system for control.
Considering the importance of maintaining stable full penetration during many welding applications, a nonlinear model of DB-GMAW full penetration is developed in this dissertation. To do that, we use machine vision techniques to monitor the welding profile of the work piece. A control algorithm based on the nonlinear model using adaptive control technique is also designed. The achievement of this dissertation provides a fundamental knowledge of a novel welding process: DB-GMAW, and a good guidance for further studies about DBGMAW.
15
Hirst, Adrian Anthony. "Fume formation in flux cored metal inert gas welding." Thesis, University of Bradford, 1990. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306180.
Full text
16
Pehkonen, Henri. "Design of Gas Shield for Friction Stir Welding Machine." Thesis, Linköpings universitet, Maskinkonstruktion, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-126605.
Full textAbstract:
The research and development of the final disposal of the nuclear waste produced by the nuclear power plants is an important work done by The Swedish Nuclear Fuel & Waste Management Co. (SKB). As the demands on a final disposal increase the laboratory equipment has to be better in order to do valid experiments. Research on how the copper canister for the spent fuel will be manufactured and handled is done at the Canister laboratory in Oskarshamn, Sweden. The work presented in this report was to design a new gas shield for the friction stir welding machine at the laboratory. The welding machine seals the canisters containing the spent fuel which are then transported to the final disposal 500 meter down in basement rock. To minimize the amount of oxide particles in the weld zone SKB have to design a better gas shield that should deliver the required atmosphere around the welding area. The work contains a pre study phase where the important things to consider when designing are collected. Then ideas are generated and concepts created for a new gas shield. These concepts are evaluated by a pair wise comparison method in order to find the most promising concept. The concept chosen is then detail designed to come as close to a manufacturable design as possible.Utvecklingen av ett slutförvar för det urbrända kärnbränslet som blir avfallsprodukten vid framställning av energi via kärnkraft är ett viktigt arbete som drivs av Svensk Kärnbränslehantering AB. Då kraven och bevisningen på huruvida ett slutförvar ska utföras på ett säkert sätt måste experimenten och försöksutrustningen bli bättre för att generera tillförlitliga resultat. Forskning om hur kopparkapseln för det urbrända kärnbränslet ska konstrueras och hanteras pågår vid Kapsellaboratoriet i Oskarshamn. Arbetet som presenteras i denna rapport tar upp konstruktionen av ett nytt gasskydd till friktionsomrörningssvetsningsmaskinen på Kapsellaboratoriet. Svetsmaskinen försluter kapslarna med radioaktivt avfall vilka sedan transporteras 500 meter ner i det svenska urberget. För att minska mängden oxidpariklar kring svetsområdet måste SKB tillverka ett nytt gasskydd vilket bör uppfylla de krav på atmosfären kring svetsområdet som finns. Arbetet består av en forsknings- och informationssamlingsfas där viktiga aspekter och problemområden hittas. Sedan genereras idéer och nya koncept på gasskydd fås fram. Koncepten utvärderas parvis med metoden ”pair wise comparison” för att hitta det mest lovande konceptet. Konceptet detaljkonstrueras och tillslut fås en design vilken är så nära tillverkningsbar som möjligt.
17
Lindmark, Terese. "Welding parameter window for Tandem gas-shielded metal arc welding and fatigue in welded T-joints." Thesis, University West, Department of Technology, Mathematics and Computer Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-828.
Full text
18
Davies, Mark H. "Numerical modelling of weld pool convection in gas metal arc welding /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phd2563.pdf.
Full text
19
Smailes, Allan J. "Thermal modelling of gas metal arc welding using finite element analysis /." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09ENS/09enss635.pdf.
Full text
20
Jones, Steven Alan. "Refinement of TI-6%AL-4%V weld metal structures during gas-tungsten arc welding." Thesis, Open University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288987.
Full text
21
Mazidi, Aimal. "Comparison of a new, high precision, energy efficient welding method with the conventional Gas Metal Arc Welding on high carbon steel base metal." Thesis, Högskolan Väst, Avd för tillverkningsprocesser, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-6860.
Full textAbstract:
CMT+P welding is less susceptible to hot cracking than the MAG welding process due to use of low heat input properties. Solidification cracking was found in all weld specimens that had greater 0.39KJ/mm heat inputs. Cracking occurs because of the contraction stresses generates during cooling. Hydrogen cracking is found in HAZ with low heat input parameters, this type of cracking occurred because of very rapid cooling and therefore not enough time to allow the hydrogen to dissipate from the specimen. To eliminate this type of cracking the experiment could be repeated by adding heating during welding to control and reduce the cooling rate. Due to high carbon content in the steel and very fast cooling the microstructure of the weld is martensitic in the base metal as well as the HAZ. Microstructure in the weld and base metal is martensitic due to high carbon con-tent and rapid cooling. At low heat inputs dilution is less and therefore lower carbon content in weld pool. Better weld appearance and weld quality is achieved with CMT+P welding process than the conventional GMA welding processes because of the new wire movement technology during welding
22
Wang, Ge. "NUMERICAL ANALYSIS OF METAL TRANSFER IN GAS METAL ARC WELDING." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_diss/538.
Full textAbstract:
In gas metal arc welding (GMAW), metal transfer plays a crucial role in determining the quality of the resultant weld. In the present dissertation, a numerical model with advanced computational fluid dynamics (CFD) techniques has been developed first in order to provide better numerical results. It includes a two-step projection method for solving the incompressible fluid flow; a volume of fluid (VOF) method for capturing free surface; and a continuum surface force (CSF) model for calculating surface tension. The Gauss-type current density distribution is assumed as the boundary condition for the calculation of the electromagnetic force. The droplet profiles, electric potential and velocity distributions within the droplet are calculated and presented for different metal transfer modes. The analysis is conducted to find the most dominant effects influencing the metal transfer behavior. Comparisons between calculated results and experimental results for metal transfer under constant current are presented and show good agreement. Then, our numerical model is used to study a proposed modified pulsed current gas metal arc welding. This novel modified pulsed current GMAW is introduced to improve the robustness of the welding process in achieving a specific type of desirable and repeatable metal transfer mode, i.e., one drop per pulse (ODPP) mode. This new technology uses a peak current lower than the transition current to prevent accidental detachment and takes advantage of the downward momentum of the droplet oscillation to enhance the detachment. The calculations are conducted to demonstrate the effectiveness of the proposed method in achieving the desired metal transfer process in comparison with conventional pulsed current GMAW. Also, the critical conditions for effective utilization of this proposed method are identified by the numerical simulation. The welding operational parameters and their ranges are also calculated and the calculated results further demonstrate the robustness of this new GMAW technique in achieving high quality welding.
23
Khalaf, Gholam Hossein. "Neuro-fuzzy control modelling for gas metal arc welding process." Thesis, Loughborough University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263585.
Full text
24
Byrne, N. J. "Automation of MIG (Metal Inert Gas) welding equipment using microprocessors." Thesis, University of Liverpool, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380072.
Full text
25
Jönsson, Pär Göran. "Arc parameters and metal transfer in gas metal arc welding." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12470.
Full text
26
Xu, Jun. "Dynamic thermal tensioning for welding induced distortion control /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/7145.
Full text
27
Tazedakis, Athanassios S. "Orbital plasma welding of small bore tubes." Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/10436.
Full textAbstract:
This work was primarily motivated by the industrial need for control of problems associated with the Gas Tungsten Arc Welding (GTAW) of small bore titanium and austenitic stainless steel tubes. These include: pore creation and entrapment in the weld zone, and variability of the fusion zone geometry. The primary aim of this study was the development of a low current orbital plasma welding capability using a structured approach which could lead to defect minimisation. The methodology should also have the potential to be used in a number of different conditions, extending the use of plasma welding in both melt-in and keyhole modes for the orbital welding of small bore tubes. The project originally involved the modification of a totally enclosed orbital GTAW welding head for low current welding operations. It was established that for the current range required for small bore and small to medium thickness tubes, the use of a solid copper torch was sufficient to provide the required heat absorption. A stable arc was produced even for very low current values (down to 7A) while arc voltages were within the operating range of a standard GTA welding power source. Procedural (i.e. off line) control was adopted for identification and optimisation of welding parameters. Since no procedure was available for the proposed welds it was necessary to generate the parameters required for the production of consistent weld profiles. Simultaneously, an expert system has been developed for the determination of optimum process parameters based on empirical models, developed using statistical techniques. Parameter combinations were selected based on physical as well as statistical relevance, providing a measure of confidence when predicting the required weld bead output characteristics. The approach also indicates the influence of the major input parameters on weld bead geometry and defect formation, such as undercut. Two quality acceptance criteria were employed during this investigation, weld bead dimensional accuracy, and the type and seriousness of defects present (penetration / burn-through, porosity and undercut). Off line programming was utilised to control heat build up and to ensure welds were obtained with the desired geometry and minimal defect levels. The end result was the development of a prototype system for low current orbital plasma welding (in both melt-in and keyhole mode) of small bore tubes in a totally enclosed head. Tolerant procedures for low current orbital melt-in and particularly keyhole welding have been generated and a systematic methodology for the prediction and optimisation of welding procedures based on predetermined criteria has been developed.
28
Tipaji, Pradeep Kumar. "E-design tools for friction stir welding: cost estimation tool." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/Tipaji_09007dcc8043f642.pdf.
Full textAbstract:
Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed February 5, 2008) Includes bibliographical references (p. 29-31).
29
Åstrand, Erik. "A Framework for optimised welding of fatigue loaded structures : Applied to gas metal arc welding of fillet welds." Doctoral thesis, Högskolan Väst, Forskningsmiljön produktionsteknik(PTW), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-9339.
Full textAbstract:
Welding is a key process for heavy steel structures, but it is also a weak link in the structure since fatigue fractures in welds are a common cause of failure. This thesis proposes several changes in order to improve the fatigue properties in acost effective way, enabling reduced weight and reduced cost of welded structures. The main idea is to adapt the weld requirements and welding procedures to the load conditions of the weld. This approach ensures that the main focus in the welding process is the critical characteristics of the welds fatigue life properties. The fatigue life critical properties are most often related to the geometrical factors of the weld such as the radius at the weld toe or the penetration in the root. The thesis describes a holistic view of the subject and covers fatigue, weld quality, weld requirements and welding procedures. It becomes evident that the traditional way of working without a direct connection to fatigue is not the best. With an adaptation to the load conditions and fatigue, it is possible to enhance the fatigue life and reduce the welding cost. The main challenge is to connect the welding process, weld requirements and fatigue life properties. It is needed for an optimised welding process of heavy structures subjected to fatigue and toget a predictable fatigue life. Welds optimised for enhanced fatigue life properties are not necessary accepted according to the requirements in a current standard. Several welding procedures are proposed for improving the fatigue life properties of the weld, which indicate a high potential for enhanced fatigue lifeof fillet welds. The idea is to replace the "standard" fillet weld with three different weld types: (i) Welds with deep penetration, (ii) Welds with large weld toe radius and (iii) Welds produced with low cost. Together with customised requirements and reduced over-welding there is a vast potential for reduced weight, reduced cost and increased productivity.The main contribution of this thesis work is the cross-functional studies including design, analysis, production and quality control. This gives a framework for improvements supporting reduced cost and reduced weight of VIII welded structures without reducing the fatigue strength. Many shortcomings have been highlighted to change the welding from a state where welds are done in a way as they "always" have, by tradition, to a more contemporary situation where weld requirements and welding procedures are actively chosen to match the load conditions of the weld. This result in requirements and welding procedures which actually are connected to the fatigue properties as defined by the loading conditions, and where auditors with high probability can say that an accepted weld actually is better than a rejected weld.
30
Chen, Xiao-Qi. "Sensor based automatic control system for narrow gap TIG welding." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278614.
Full text
31
Tam, Joseph. "Methods of Characterizing Gas-Metal Arc Welding Acoustics for Process Automation." Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/859.
Full textAbstract:
Recent developments in material joining, specifically arc-welding, have increased in scope and extended into the aerospace, nuclear, and underwater industries where complex geometry and hazardous environments necessitate fully automated systems. Even traditional applications of arc welding such as off-highway and automotive manufacturing have increased their demand in quality, accuracy, and volume to stay competitive. These requirements often exceed both skill and endurance capacities of human welders. As a result, improvements in process parameter feedback and sensing are necessary to successfully achieve a closed-loop control of such processes. One such feedback parameter in gas-metal arc welding (GMAW) is acoustic emissions. Although there have been relatively few studies performed in this area, it is agreed amongst professional welders that the sound from an arc is critical to their ability to control the process. Investigations that have been performed however, have been met with mixed success due to extraneous background noises or inadequate evaluation of the signal spectral content. However, if it were possible to identify the salient or characterizing aspects of the signal, these drawbacks may be overcome.
The goal of this thesis is to develop methods which characterize the arc-acoustic signal such that a relationship can be drawn between welding parameters and acoustic spectral characteristics. Three methods were attempted including: Taguchi experiments to reveal trends between weld process parameters and the acoustic signal; psycho-acoustic experiments that investigate expert welder reliance on arc-sounds, and implementation of an artificial neural network (ANN) for mapping arc-acoustic spectral characteristics to process parameters.
Together, these investigations revealed strong correlation between welding voltage and arc-acoustics. The psycho-acoustic experiments confirm the suspicion of welder reliance on arc-acoustics as well as potential spectral candidates necessary to spray-transfer control during GMA welding. ANN performance shows promise in the approach and confirmation of the ANN?s ability to learn. Further experimentation and data gathering to enrich the learning data-base will be necessary to apply artificial intelligence such as artificial neural networks to such a stochastic and non-linear relationship between arc-sound and GMA parameters.
32
Woods, Steven C. "Investigation of the effect of pulsing shielding gas in arc welding." Connect to resource, 2006. http://hdl.handle.net/1811/6450.
Full textAbstract:
Thesis (Honors)--Ohio State University, 2006.Title from first page of PDF file. Document formatted into pages: contains 32 p. ; also includes graphics. Includes bibliographical references (p. 23). Available online via Ohio State University's Knowledge Bank.
33
Azar, Amin S. "Dry Hyperbaric Gas Metal Arc Welding of Subsea Pipelines : Experiments and Modeling." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produktutvikling og materialer, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-17721.
Full textAbstract:
Ambitions in exploration of oil and gas fields at deeper water depth require continuous investigation and maintenance. The transportation pipelines laid in deep waters are both subjected to corrosion and buckling due to environmental phenomena. They may also often undergo branching (namely hot tapping) to redirect (or add to) the transportation paths. Mechanical joints and welding are both considered as available alternatives when sectioning and replacement of the pipes at shallow waters is necessary, yet, welding is more promising for deep waters where remote operation is central. Fusion welding on the other hand comprises several technological detractions for sound operations under high ambient pressures disregarding its low cost and flexibility. The foremost detracting phenomenon in the arc welding is called ‘arc root constriction’, which is defined as arc geometry shrinkage under the increased pressure. Consequently, the power delivery to the weld pool at different pressure levels is a major worry. Effects of ionization and dissociation energies of different gases and mixtures, partial pressure of environmental gases including hydrogen and oxygen, gasification and degasification of the weld metal, inclusions that affect the phase transformation, absorption and desorption kinetics, oxidation and deoxidation reactions and many more are the phenomena that can possibly be altered by the gas type and ambient pressure level. Spattering and fume generation is a problematic issue since the arc is rather unstable under high pressure. Thus, seeking the effect of different chamber gas mixtures on welding parameters, final microstructure and mechanical properties is the main objective of this work. Statistical analysis of the collected voltage and current waveforms is carried out to identify the source of arc misbehavior and instability (discussed in Paper I). The stochastic parameters is related to the electrical stability and resolved into a number of varying welding parameters. The datasets are representing the effects of using pure argon under 14 incrementally increased pressure levels. Fast Fourier Transformation (FFT) is used to characterize the frequency domain of the waveforms. Auto-correlation Function (AF) and Power Spectral Density (PSD) were calculated assuming the Wiener-Khinchin theorem. Considering the AF, it is possible to visualize the deteriorating stability of the arc. The rate of stability degradation is quite gentle after 20 bar, though, huge differences were observed from 1 to 20 bar. The characteristic frequencies of 100-150 Hz and 350-400 Hz were observed. The first range can be associated with the mass transfer or molten droplet launch frequency and the latter range is representative of the rectified mains. The spread of large low-frequency peaks at higher pressures is illustrating the mass transfer deterioration. The aforementioned peaks were found above 125 bar where the range of the characteristic frequency peaks in voltage and current waveforms started to deviate. The calculated arc power is higher at high-pressure range while the weld bead geometry was barely varied. It implies that the arc efficiency factor decreases at high pressures. The heat source dimensions and heat efficiency factor are two major inputs for finite element (FE) simulations of the weld. However, a systematic classification of these factors was hardly available prior to this work. Additionally, to the best of author’s knowledge, the direct high-speed observation of the arc inside the hyperbaric welding chamber has not been investigated in detail by far due to several technological issues. The varying bead-on-plate welds including the end crater appearance can possibly be good candidates to categorize the FE heat source dimensions. Double-ellipsoidal heat source (Goldak’s Model) was implemented in WeldSimS® FE code that is used in this study. Since the model incorporates two superimposed reference heat sources, the amount of dissipated heat from each source should be differentiated. An intermediate heat source model was employed for this purpose. The latter model is after Myhr and Grong that is called distributed point heat sources. This model can be accurately fit to the weld cross section geometry if calibrated accurately. The calibrated parameters were found to be very close to the ones required by Double-ellipsoidal heat source model. By using this approach, not only the effect of welding parameters on weld bead geometry can be categorized, but also the spent time for double-ellipsoidal heat source adjustments will be cut by 90%. A Gaussian heat source was also employed for welding thermal cycle simulations. Accompanying experiments suggested that the thermal gradients hardly change as pressure elevates. However, it was found that the increased pressure level might not necessarily result in higher or lower cooling rates despite the geometrical changes. In a parallel investigation, the metallurgical effect of different shielding environments on phase transformation and mechanical properties of the bead-onplate weld samples was studies. Electron backscattered diffraction (EBSD) and orientation imaging microscopy (OIM) techniques were used to identify the effect of five different shielding environments on the phase transformation. Argon and Helium chamber gases offer the conditions that facilitate the highest amount of acicular ferrite transformation, yet, they show some differences in a number of crystallographic details. CO2 gas provided conditions for a lot of porosity in addition to the dominant polygonal ferrite/bainite transformation. He+½CO2 mixture resulted in bainite transformation that was found to follow the maximum heat flow direction in terms of crystallographic orientations. Very small sized tensile and single-edged notch bending (SENB) samples were machined from the weld metal material. The tests revealed that the best mechanical properties are associated with the He chamber gas and the poorest properties were presented by the samples welded in He+½CO2 shielding environment. It was also observed that there is a good correlation between the acquired acoustic signals and the fracture properties of the weld samples
34
Posinasetti, Praveen. "Process modelling and control of pulse gas metal arc welding of aluminum." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16530/.
Full textAbstract:
Recent developments in materials and material joining [specifically Aluminum and Pulse Gas Metal Arc Welding (GMAW-P) technology] have increased the scope and extent of their areas of application. However, stern market demand for the improved weld quality necessitates the need for automation of the welding processes. As a result, improvements in the process parameter feedback, sensing and control, are necessary to successfully develop the automated control technology for the welding processes. Hence, several aspects of the GMAW-P process have been investigated in this study in order to improve its control techniques.
Welding was conducted on 6XXX aluminium, using 1.2 mm diameter 4047 aluminum electrode and argon shielding gas. An extensive collection of high speed camera pictures were taken over a wide range of pulse parameters and wire feed rates using a xenon shadowgraph setup to improve understanding of the physics of GMAW-P process. Current and voltage signals were recorded concurrently too.
This investigation explores the effects of different process parameters namely pulsing parameters (Peak current (IP), Base Current (IB), Peak time (TP), Base Time (TB)) and wire feed rate on metal transfer phenomena in GMAW-P. Number of drops per pulse, arc length and droplet diameter were measured for aluminium electrodes by high speed videography. The pulsing parameters and wire feed rate were varied to investigate their effect on the metal transfer behaviour. Analysis showed that transition between the different metal transfer modes is strongly influenced by the electrode extension. Lower electrode extension reduced the number of droplets detached per pulse, while at higher electrode extension, spray mode is observed due to increased influence of the resistance heating.
Analysis of the current and voltage signals were correlated with the high speed films. A simple derivative filter was used to detect the sudden changes in voltage difference associated with metal transfer during GMAW-P. The chosen feature for detection is the mean value of the weld current and voltage. A new algorithm for the real time monitoring and classification of different metal transfer modes in GMAW-P has been developed using voltage and current signals. The performance of the algorithm is assessed using experimental data. The results obtained from the algorithm show that it is possible to detect changes in metal transfer modes automatically and on-line.
Arc stability in the GMAW-P has a close relationship with the regularity of metal transfer, which depends on several physical quantities (like voltage, current, materials, etc.) related to the growth and transfer of the metal droplet. Arc state in GMAW-P can be assessed quantitatively in terms of number of drops per pulse, droplet diameter and arc length. In order to assess the arc state in GMAW-P quantitatively, statistical and neural network models for number of drops/pulse, droplet diameter and arc length were developed using different waveform factors extracted from the current waveform of GMAW-P. To validate the models, estimated results were compared to the actual values of the number of drops per pulse, droplet diameter and arc length, observed during several welding conditions.
Determination of stable one drop per pulse (ODPP) parametric zone containing all the combinations of peak current (IP), base current (IB), peak time (TP), and base time (TB) that results in stable operation of GMAW-P, is one of the biggest challenges in GMAW-P. A new parametric model to identify the stable ODPP condition in aluminium which also considers the influence of the background conditions and wire feed has been proposed.
Finally, a synergic control algorithm for GMAW-P process has been proposed. Synergic algorithm proposed in this work uses the sensing and prediction techniques to analyse state of the arc and correct the pulsing parameters for achieving the stable ODPP. First arc state is estimated using the signal processing techniques and statistical methods to detect the occurrence of short circuit, unstable ODPP or multiple drops per pulse (MDPP) in GMAW-P system. If the arc state is not stable ODPP, then parametric model and genetic algorithm (GA) is used to assess the deviation of the existing pulsing parameters from the stable operation of GMAW-P process and automatically adjust pulsing parameters to achieve stable ODPP.
35
Ogunbiyi, T. E. B. "Process monitoring and adaptive quality control for robotic gas metal arc welding." Thesis, Cranfield University, 1995. http://dspace.lib.cranfield.ac.uk/handle/1826/4604.
Full textAbstract:
The aim of this research was to develop an adaptive quality control strategy for robotic gas metal arc welding of thin steel sheets. Statistical methods were used to monitor and control the quality of welds produced. The quality of welds cannot be directly measured during welding. It can however be estimated by correlating weld quality parameters to relevant process variables. It was found sufficient to do this using welding current and voltage transient signals only. The strategy developed was problem solving oriented with emphasis on quality assurance, defect detection and prevention. It was based on simple algorithms developed using multiple regression models, fuzzy regression models and subjective rules derived from experimental trials. The resulting algorithms were used to control weld bead geometry; prevent inadequate penetration; detect and control metal transfer; assess welding arc stability; optimise welding procedure; prevent undercut; detect joint geometry variations. Modelling was an integral part of this work, and as a feasibility study, some of the models developed for process control were remodelled using 'Backpropagation' Artificial Neural Networks. The neural network models were found to offer no significant improvement over regression models when used for estimating weld quality from welding parameters and predicting optimum welding parameter. As a result of the work a multilevel quality control strategy involving preweld parameter optimisation, on line control and post weld analysis was developed and demonstrated in a production environment. The main emphasis of the work carried out was on developing control models and means of monitoring the process on-line; the implementation of robotic control was outside the scope of this work. The control strategy proposed was however validated by using post weld analysis and simulation in software.
36
Richardson, I. M. "Properties of the constricted gas tungsten (plasma) welding arc at elevated pressures." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280909.
Full text
37
Göktuğ, Gökhan. "On the effect of environmental pressure on gas tungsten arc welding process." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/39620.
Full text
38
Ribeiro, A. F. M. "Automated off-line programming for Rapid Prototyping using Gas Metal Arc Welding." Thesis, Cranfield University, 1995. http://dspace.lib.cranfield.ac.uk/handle/1826/10430.
Full textAbstract:
Rapid Prototyping is a recent CAD/CAM based manufacturing technique which
produces prototypes of components in a fraction of the time normally required. This
technique normally involves drawing the part as a 3 Dimensional solid model using a
CAD
program and then 'printing' it in 3 Dimensions. The raw material can be a
photopolymer or thermoplastic which solidifies when in contact with light. Other
materials are available
although producing the final parts a 100% metal is not very
usual.
Some disadvantages of these techniques are:
a) 100% metal prototypes cannot normally be made directly.
b) only prototypes can be produced instead of the final component.
c) machine size limits the size of the final component.
d) very thin layers are deposited. This makes the build up more time consuming and
mostly suitable to small components.
The main
objective of this work was to overcome these disadvantages by creating a new
Rapid Prototyping technique using Robot Fusion Welding.
In the
pre-production phase, it is important to make a prototype not only for
visualisation but also to test and assess it in its real function. Therefore, prototyping in
resin a component which is going to be made in metal has no use for assessing purposes.
This
technique, besides making the prototype in metal can also be used as a production
technique to make the real usable final component. It even allows the use of different
metals
along its structure in the welding filler wire is changed. This makes it possible to
have different structural characteristics in the same component a required.
None of the
slicing algorithms developed for other Rapid Prototyping processes were
applicable to this new technique and therefore a new slicing concept (and routine) was
created
specifically. I addition, an interface for off-line programming and quality
documentation was evolved. The technique developed has been tested by fabricating
several 'test'
components and both the dimensional accuracy and component integrity
have been evaluated and proved to be successful.
39
de, Souza Nayara. "Total Fume Emissions and Emission Factors Applicable to Gas Metal Arc Welding." ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2603.
Full textAbstract:
Welding is a common industrial practice that has the potential to emit air pollutants. Emission factors are useful indicators to help in the understanding of the extent of pollution from a process and managing them to reduce or minimize health impacts. The objective of this thesis is to determine emission factors applicable to the gas metal arc welding (GMAW), under varying current and voltage conditions. The most used base metals and an electrode for the shipbuilding industry were considered. A weld fume chamber was used to achieve the project goals along with standard sampling and analytical procedures. Three test runs were performed for each sampling scenario to ensure repeatability. The EPA EF average for MS experiments with the ER70S-6 electrode is 5.2 g/kg, and for SS experiments with the ER316L-Si electrode is 3.2 g/kg, while the average results for this study were 6.81 g/kg and 3.28 g/kg respectively.
40
Adonyi-Bucuroiu, Ioan. "A study of arc force effects during submerged gas tungsten-arc welding /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487671108304733.
Full text
41
Woodward, Neil J. "Pool oscillations and cast variations : penetration control for orbital tig welding of austenitic stainless steel tubing." Thesis, Cranfield University, 1997. http://dspace.lib.cranfield.ac.uk/handle/1826/4512.
Full textAbstract:
Pool oscillations in tungsten inert gas welding pools have been used in a closed-loop control system for orbital welding of ultra high purity tubing, determining a target level of penetration by altering the welding current in real-time. The technique is ideally suited to this application since it is does not contravene the cleanliness requirements for the inner bore and can be implemented outside the small orbital heads that are commonly used. The results presented in this thesis show how clear pool oscillation signals in extremely small molten pools can be monitored by optimising the welding conditions and signal processing of the arc voltage signal. As an indicator of the likely variation in cast behaviour present particularly in austenitic stainless steels, a 'time-to-penetrate' characterisation was made of the materials, using the time of the transition from the Mode 1 to the Mode 3 oscillation behaviour as the measured variable. By applying the test across a range of welding currents, significant insight was obtained into the cast and associated penetration behaviour. Late transitions indicated casts that exhibited significantly different responses to the more usually applied welding procedures, especially at the lower levels of welding current (highlighting their potentially more problematic penetration behaviour). It was shown that the established theoretical models were difficult to apply with certainty to moving weld pools, and consequently a fuzzy logic model was used in the control strategy. The closed-loop system comprised a user-interface PC, a control rack and commercial welding power source - control signals were applied every 2 to 3 Hz. Mode 3 pool oscillations were found to offer a more than satisfactory sensitivity to the inner bead width created for the various casts of 1.65 mm wall thickness materials studied.
42
Sgro, Sergio Domenico. "The efficacy of teaching oxyacetylene welding prior to gas metal arc welding for introductory materials and process courses in industrial technology." [Ames, Iowa : Iowa State University], 2006.
Find full text
43
Pitrun, Miroslav. "The effect of welding parameters on levels of diffusible hydrogen in weld metal deposited using gas shielded rutile flux cored wires." Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20050202.153920/index.html.
Full text
44
Schupp, Peter E. "Weldpool flow visualization studies during gas tungsten arc welding of steel and aluminum." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/24109.
Full text
45
Pendlebury, Mark. "The design and production of an automated TIG (Tungsten Inert Gas) welding machine." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240265.
Full text
46
Wu, Gwo-Donq. "A critical investigation of current and heat distributions in gas tungsten welding arcs /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487848891511596.
Full text
47
da, Costa Pépe Nuno Vasco. "Advances in gas metal arc welding and application to corrosion resistant alloy pipes." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/4501.
Full textAbstract:
According to recent estimations, the construction of pipelines will continue to increase during the next thirty years, in particular as a result of oil and gas discoveries in remote locations. Significant advances in welding technology during the last ten years have potential to provide improvements in productivity, quality and structural integrity of pipe girth welds. In this thesis, several new processes Lincoln STT, Lincoln RapidArc, Fronius CMT, Fronius CMT-P and Kemppi FastROOT have been compared the first time to the GMAW-P to understand how these new waveforms operate for pipe welding. The process setting parameters have been analysed to understand their effect on metal transfer and arc stability control, and on bead shape characteristics. Although all waveforms present similar burn-off ratios, individual waveforms differ considerably, and especially the arc voltage waveform. This leads to considerable differences in the mechanism of metal transfer and the stability of the processes under similar experimental conditions. Understanding of these new waveforms in terms of the effect of setting parameters in the mechanism of metal transfer, process stability and melting phenomena provides a basis for assessing the potential of these processes for a range of applications, and in particular application to CRA pipe root welding Since the arc energy is the overall energy delivered from the power source at the contact tip of the torch, and part of that energy is not absorbed by the workpiece, research was performed to measure the process efficiency associated with some of these waveforms and process setting conditions. The study led to a better understanding of the potential errors in calculating process efficiency. The results obtained show that all the short-circuiting waveforms analysed (i.e. CMT, STT and FastRoot) had a similar process efficiency of 90±3%, while pulse spray waveforms (GMAW-P, CMT-P and RapidArc) are characterized by lower process efficiency, approximately 78±3%. The application of these waveforms to the welding a narrow groove pipe with a “J” groove design was investigated. These analyses were focused on the variation of bead shape characteristics and welding quality performance based on the analysis of the conditions that result in lack of penetration and top bead defects, such as lack of side wall fusion or undercutting. It was observed that RapidArc and CMT-P are able to satisfy the quality requirements, i.e. full penetration and absence of defects for the specific conditions described in this thesis. High welding speeds (up to 1m/min) were achieved with these processes, four times the typical speed 0.25m/min. Finally, the shielding gas plays an important role in terms of quality and weld bead performance. This led to an optimization of the shielding gas composition used, based on mixtures of carbon dioxide, argon and helium. Statistical modelling was undertaken to optimize the shielding gas mixtures using RapidArc and CMT-P waveforms. In parallel, a new purging shielding gas device was designed to achieve a weld root free of oxidation.
48
Zelenitca, Darina. "Design MIG/MAG svářečky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416428.
Full textAbstract:
The topic of this diploma thesis is the design of a MIG/MAG welding machine, suitable for locksmiths and workshops. The diploma thesis includes the analysis of existing products from the design and technical point of view and deals with the design of welding machine. The proposed concept focuses on interactive and modern look of the machine and comfortable manipulation and easy operation. The design itself offers a possible direction of morphology of welding machines in the future.
49
Riggs, Mark R. "TIG Welding of Nickel Titanium to 304 Stainless Steel." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397607979.
Full text
50
Turner, Brian Edward. "Evaluation of hot gas welding techniques for the joining and repair of polymeric bumper materials." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291085.
Full text