Modified Current Waveforms for Welding Applications

American Journal of Engineering and Applied Sciences, 2015

This study aims to develop an automatic arc welding system capable of welding irregular and moving joints which are difficult to weld manually. The motivation of this research comes from the need to produce uniforms weldings on regular and irregular surfaces by automatic means. The system consists of a personal computer equipped with A/D interface card connected to an electric current sensor and two electric motors controlled via electronic circuits. A control program receives the electric current measurements and makes the necessary calculations for the correct vertical motion of the welding electrode. A modified PID controller was used to control the process dynamics. An X-Y mechanism with two electric motors was developed to control the motion of the electrode as well as the work piece. A comparison was made between two welded specimens; one was welded by traditional manual method and, the second by using automatic control mechanism. The weld distribution through the welded joints was compared. Different irregular joints were also compared for the manual and automatic control welding methods. It was found that the control system works with an accuracy of ±28 µm for a 1.01 mm weld thickness of a flat weld by controlling the current at 60 A within a standard deviation of ±1.45 A. As a result welds with uniform thickness were obtained. The uniform heating further contributes to a uniform microstructure in the weld area. The implications of this research will be enhanced automation of the welding process in industry, with improved control over its uniformity, especially while welding around circular objects and during vibrating or unstable conditions.

This work investigates the study of the experimental weldability in magnetic pulse welding process of a one material assembly (aluminium AA6060T6) and a dissimilar metal couple (aluminium6060T6/copper). The weld quality is defined using a destructive process allowing measuring the weld dimension. A diagram charging voltage-air gap is used to establish the variance of weldability. With the criterion of width of the weld, this representation is able to determine the operational weldability window. The lower boundary is defined by the case of bad weld, i.e. an insufficient bonding, and the upper boundary by the case of detrimental weld, i.e. a weld susceptible to crack. The weld is able to undergo a plastic deformation prior to failure. A large weld is more potentially ductile. A numerical modelling of a mechanical destructive push out test could be helpful to characterise the weld in a quantitative manner. Finally, the material dissymmetry as considered in this study notably reduces t...

2020

Pulsed current gas metal arc welding (PC-GMAW) is characterized by periodically changing arc power and, thanks to its features, it allows solving complex technological issues in the creation of unique designs, and increasing the productivity of welding processes and surfacing corrosion-resistant alloys on steel. Many manufacturers of welding equipment, presently, have implemented the idea of impulse welding in their production. The data on the influence of PC-GMAW on thermal cycles of welding (TCW), however, are scattered and therefore it is difficult to compare with thermal cycles of welding characteristic for continuous current gas metal arc welding. During welding of high-carbon steels, the task is to reduce the mixing of the weld metal with the base metal and to increase the resistance of welded joints to the formation of cold cracks. For the successful application of PC-GMAW in solving the above-mentioned problems, it becomes necessary to compare the effect of pulse current gas...

A two pole type of an a.c variable current welding machine was designed and constructed. The first pole is the primary circuit and was design to have a four step coil SA, AB, BC and CE with three looping A, B, C for the variable selection of current capacity. The primary circuits was coiled with a copper wire of size gauge 13 and were given turns of 80, 20, 20 and 20 turn for step SA,AB, BC and CD respectively. The second pole is the secondary circuit side which was design to have both primary circuit and the secondary circuit lapping on each other. The primary circuit on the secondary pole was wound with copper wire of size gauge 13 and was given one step winding turn of 114 turns while the lapped secondary circuit was given one step turn of 40 turns with a tick copper wire of size gauge 8. The start to start connection style was use for the primary circuits while the secondary circuit starts and end hands were connected to the earth and tong of the welding machine respectively. Fig 9: A circuit diagram showing the detail connection of the primary circuits

Journal of Manufacturing Processes, 2012

This study investigates the experimental research of the appropriated conditions for the magnetic pulse welding of AA6060T6 tubular assembly. Some welding tests were performed with two process parameters: the charging voltage and the width of the air gap between the two parts to be welded. A torsion-shear test, associated with the material fracture surfaces observation, gives an insight about the appropriateness of the welding conditions. The failure mode of the destructive test gives a dimensional criterion of the weld that is used as weld quality. It appears that the voltage does not strongly affect the weld quality for a low gap. It is possible to find an optimal gap range giving a high weld length. When the gap is too small, it is necessary to increase the pressure on the flyer, and some cracks appear in the material. Similarly, when the gap is too large, the high impact energy damages the welded interface.

Reviews on Advanced Materials Science

Demands for improved productivity, efficiency, and quality pose challenges to the welding industry. As materials become ever more sophisticated in their chemical composition to provide ever-better functionally specific properties, a more complete and precise understanding of how such materials can be joined for optimal effectiveness and efficiency will become essential. Traditional options for welding will surely evolve, sometimes to provide unimagined capabilities. In addition, totally new methods will almost certainly emerge as evolution of materials gives way to revolution to meet unimagined new designs and design demands. The paper considers process systematization and corresponding advances of constituent technologies, discusses some of the role and future direction of welding technology, welding materials, productivity and efficiency, education and safety having an impact on future growth in welding technology. Analysis of drivers and the key needs of some manufacturing indust...

2011

In the automobile industry, Resistance Spot Welding (RSW) is widely used for its low cost, high speed, simple mechanism and applicability for automation. RSW has become the predominant means of auto body assembly, resulting in two to six thousands spot welds performed on each manufactured car. In the North American automobile industry there are approximately 100 billion spot welds, which are done every year. RSW is the joining of two or more metal parts together in a localized area by resistive heating and pressure. Small Scale RSW (SSRSW) is commonly used for medical devices and electronic components, because the welded parts are thinner and smaller compared to common RSW applications, such as automotive applications. According to a study of Edison Welding Institute, 20% of the welding quality issues are the weld schedule or power supply related. Therefore, to contribute to weld quality improvement, the study of different weld schedules or power supplies and control schemes needs to be improved by doing further studies in this area. Thus a novel power supply, which can provide a testing bench for these studies, was designed and developed in 2005 by L. J. Brown and J. Lin. This research study will focus on studying and improving weld power supplies, weld schedules and control modes. One of the goals for this research is to improve the consistency of weld nugget size and strength by using different control parameters, which will be weighted geometric averages of voltage and current. These control parameters are fed back to a Proportional Integral Derivative (PID) controller that is designed to control the Direct Current (DC) power supply for the RSW to come up with the best control parameters that will improve the consistency of the RSW spot welds. Another goal for this research is it to further develop the existing DC power supply that was designed for SSRSW by L. J. Brown, to include tip voltage measurements, and Large Scale Resistance Spot Welding (LSRSW). This goal will lead to build additional weld modules to construct a 6000A welder in the future.

Welding is a widely used technique to join metal parts. In welding processes the current flows through the arc. The welding arc may be affected by magnetic field produced in a work piece adjacent to it. Magnetic disturbance surrounding the welding arc may cause arc instability which is responsible for lack of fusion, porosity and unevenly welded joints. At the same time, there is considerable spattering which, if avoided, obviously results in good quality and economy. If the arc can be confined into the smallest possible region, it is of considerable help in improving weldability and associated properties. An attachment for welding under variable external magnetic fields has been developed as an attempt for improving arc stability and better weld beads apart from savings in electrode consumption.

In this paper, the benefits of using Magnetic Pulse machine which is belong to Non-conventional machine instead of conventional machine. Magnetic Pulse Technology is used for joining dissimilar metals, and for forming and cutting metals. It is a non contact technique. Magnetic field is used to generate impact magnetic pressure for welding and forming the work piece by converted the electrical energy to mechanical energy. It is enable us to design previously not possible by welding dissimilar materials and allowing to welds light and stronger materials together. It can be used to weld metallic with non metallic materials to created mechanical lock on ceramics, polymers, rubbers and composites. It is green process; there is no heat, no radiation, no gas, no smoke and sparks, therefore the emissions are negligible.