Introduction to welding
Welding is a process of joining different materials. The large bulk of materials that are welded are metals and their alloys although welding is also applied to the joining of other materials such as thermoplastics. Welding joins different metals or alloys with help of a number of processes in which heat is supplied either electrically or by means of a gas torch.
Abstract
Welding being the major asset and salvation for mechanical engineering, the seminar is all about the automation of major welding processes used in industries using robots, which was hitherto done manually under hazardous and perilous working environs. The seminar dwells with two major industrial welding processes namely continuous arc welding process and spot welding process.
Why Robot Spot Welding?
For larger works on spot welding the welding guns with cables attached is quite heavy and can easily exceed 100lb in weight. To assist the operator in manipulating the gun, the apparatus is suspended from an overhead hoist system. Even with this assistance, the spot-welding gun represents a heavy mass and is difficult to manipulate by a human worker at high rates of production desired on a car body assembly line. There are often problems with the consistency of the welded products made on such a manual line as a consequence of this difficulty.
Robotic Arc Welding System
Robotic arc welding (RAWS) is best suited for batch production involving frequent design changes in a component and even where different components are to be handled one after the other. This is possible due to highly flexible system provided by RAWS. However the justification for installation of such a system has to be looked through return on investment by considering all the expenses (on equipment, material handling devices, training, etc.) and the likely savings on account of increased production, improved quality, savings of energy, men-hours and materials due to the reduction in reworking of components, lower turn over of employees in the shop and reduced burden of strikes, etc.
Continuous arc welding
Arc welding is a continuous process as opposed to spot welding which might be called a discontinuous process. Continuous arc welding is used to make long welding joints in which an air tight seal is often required between the two pieces of metals being joined. The process uses an electrode in the form of a rod or a wire of metal to supply the high electric current needed for establishing the arc. Currents are typically 100 to 300A at voltages of 10 to 30GV. The arc between the welding rod and the metal parts to be joined produces temperatures that are sufficiently high to form a pool of molten metal to fuse the two pieces together. The electrode can also be used to contribute to the molten pool, depending on the type of welding process.
Sensors
The robotic arc welding sensor system considered here are all designed to track the welding seam and provide the information to the robot controller to help guide the welding path. The approaches used for this purposes divide into two basic categories.
v Contact sensors.
v Non-Contact sensors
Improved Product Quality
Improved quality is in the form of more consistent welds and better repeatability in the location of welds. Even robots with relatively unimpressive repeatability specifications are able to locate the spot welds more accurately than human operators.
Introduction
Welding technology has obtained access virtually to every branch of manufacturing; to name a few bridges, ships, rail road equipments, building constructions, boilers, pressure vessels, pipe lines, automobiles, aircrafts, launch vehicles, and nuclear power plants. Especially in India, welding technology needs constant upgrading, particularly in field of industrial and power generation boilers, high voltage generation equipment and transformers and in nuclear aero-space industry.
Conclusion
A substantial opportunity exists in the technology of robotics to relieve people from boring, repetitive, hazardous and unpleasant work in all forms of a human labour. There is a social value as well as a commercial value in pursuing this opportunity. The commercial value of robotics is obvious. Properly applied, robots can accomplish routine, undesirable work better than humans at a lower cost. As the technology advances, and more people learn how to use robots, the robotics market will grow at a rate that will approach the growth of the computer market over the past thirty years. One might even consider robotics to be a mechanical extension of computer technology.
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