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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