Aluminum laser
welding process
Overview of
aluminum welding
Aluminium and
aluminum alloys have good performance, such as high specific strength,
corrosion resistance, have a very wide range of applications in many industries,
particularly in the defense industry, machinery and other industries,
non-ferrous metals and aluminum belong in the application process requires
welding, so with the rapid development of science and technology, research of
aluminum welding technology is more and more depth. Therefore, the laser
welding technique is a major advance in science and technology.
Overview of
laser welding technology: laser welding as a new welding technology, direct
heat source is a laser welding, both to avoid waste of energy, but also can
greatly improve the welding efficiency. At the same time, the laser welding
robot or CNC machine tools as a movement system, reduce participants can reduce
the waste of labor, improve the welding efficiency. Laser heat source in
addition to the advantages of renewable and clean pollution-free, but also can
transmit high degree of focus and good performance, so you can converge all the
energy concentrated at one point, to avoid heat loss and waste. Therefore,
laser welding can improve welding efficiency and speed and the quality of the
welds. Because the laser beam welding by continuous or pulsed laser beam to
achieve, and therefore when the laser beam is irradiated directly on the
surface of the aluminum alloy, the heat can be rapidly diffused into the
surface of the metal inside the aluminum, the aluminum alloy melted to form a
fast a weld simultaneously formed on the metal melted a reaction that will
eventually melted down aluminum surface depressions formed holes. This hole has
a powerful effect, all the energy generated can absorb the laser beam
irradiation, and also create tension high-temperature steam, the steam pressure
and the parietal surface to form a dynamic balance.
Laser welding
power 1.1
Laser welding
has some power, only when the welding power reaches a certain height in order
to allow welding to stable and sustainable, otherwise the welding work only on
the surface of aluminum, making the surface of aluminum melts, thereby welding
can not succeed performed. Laser welding power can reach the surface of the
aluminum alloy and internal height of all welding, even higher than this, the
laser welding of aluminum alloy grade can improve the efficiency and speed and
quality.
Laser welding
speed 1.2
Because of high
power laser welding, so the welding speed can be increased accordingly, to
continuously improve the welding speed decreasing penetration can be made, on
the contrary, if the speed is slowed down, it will be over the aluminum alloy
to be welded or weld penetration and, Therefore, the choice of welding laser
welding can reduce the proportion of failed and thus greatly reduce welding
costs.
1.3 Advantages
of laser welding
Increase energy
density, improve the welding quality and increase welding accuracy and density,
welding efficiency, high-speed, low cost welding, welding can be performed
under special conditions, affect other parts of the small aluminum alloy
welding.
2 laser welding
applications in various fields
2.1 Application
of the oil pipeline
In the oil
pipeline, the application of aluminum pipes can be increased diameter pipe,
pipe wall thickening of the oil pipeline, so that the pipeline can transport
more oil within a certain time. Oil transport has a very high risk, such as the
quality of the oil leak, for property damage is difficult to estimate the
casualties and pollution of the environment and groundwater pollution, so the
aluminum pipes must pay special attention during welding, improving welding
laser welding at this point you can play a huge role, by laser welding, can be
controlled in line with the welding process, the welding operation can be carried
out under the premise without beveling, welding forming, high-quality welds,
full to avoid the risk of oil spills, improve the security of oil
transportation.
2.2 applications
in the automotive manufacturing industry
With the rapid
development of the times and people's living standards increasing speed, go by
car have become accustomed to, and the quality requirements of the automotive
people have become more sophisticated, so the automobile industry are
constantly looking for new materials and techniques to improve car quality,
laser welding technology in the automotive industry to the more widely used.
The first US aluminum laser welding technology into the automotive industry to
which, after a series of experiments, the laser welding of aluminum alloy out
of the car, a thin aluminum laser welding after molding manufacturing, not only
greatly reduce the weight of the body and reduces the automobile manufacturing
process, improve production efficiency, the majority of the automotive industry
welcomed with favor.
2.3 in the
aerospace industry
As we all know,
the aerospace industry requires a highly precise highly accurate material
manufactured aircraft and a series of spacecraft, and also very stringent
weight requirements for the machine itself, with the laser welding of aluminum
alloy planes and other machines that can make the body than usually about 20%
can reduce the manufacturing cost has been greatly reduced. For example, the
German condominium component manufacturers using laser welding technology to
produce aluminum alloy A350 family of aircraft parts and achieved great
success.
3 difficulty
laser welding technology of aluminum
3.1 aluminum
alloy reflective laser
Because aluminum
is a non-ferrous metals, all kinds of light have a very strong reflection of
the laser beam as a more intense, the surface of the aluminum alloy is more
likely to cause reflection, in other words, non-ferrous metals such aluminum
for the laser light having a high reflectance and absorption rate smaller. In
addition, the metal has a thermal conductivity, so aluminum thermal
conductivity also has a strong, easy to use when laser welding, laser or heat
on the reflection of the laser guide moved out quickly, resulting in the
failure of aluminum welding . Therefore, in the laser welding of aluminum
alloy, pay strict attention and quickly increase the power density of the
laser, or prevented from being reflected is conducted, for in time with extreme
high density aluminum alloy welding, so you can avoid reflective and other
problems.
3.2 When the
laser welding of aluminum alloy to be fully prepared
Because aluminum
has a lively, susceptible to oxidation and other features on its surface easily
attached to a lot of dust, water, etc., so the welding process, if not make
adequate preparations, attached to the surface of things easy to stay with the
rapid laser welding aluminum alloy surface, thus affecting the quality of
aluminum alloys and welding results. Therefore, prior to the welding of
aluminum alloy, the need for clean aluminum surface, the surface oil and other
clean out. While preventing oxidation occurs during welding caused by
explosions and other security threats, but also the need for a metal oxide film
on the surface of a thorough cleaning, completely remove the oxide film.
Laser welding
defects existing aluminum 4
Although the
laser welding of high efficiency, high speed and can significantly reduce the
cost, laser welding, there are many shortcomings, only to find out and solve
all these defects, and be able to make aluminum laser welding technology has
been more widely used.
4.1 porosity
defects
In the above
proposed appropriate porosity to maintain internal and external balance
aluminum, however, the excess will be large number of bubble defects is
difficult to avoid a large number of pores, pore instability occurs when a
large number of pores in the aluminum alloy inside scurrying easy to make
cracks in welded parts, so clear the pores will be one of the important defect
aluminum laser welding technology need to break.
4.2 Thermal
Crack
The application
of laser technology, the need to raise the temperature and density in order to
achieve the purpose of quick welding, so prone to crack special aluminum alloy
surface, so that the weld failed, in response to thermal cracking, scientists
have come up with ways to deal with that in laser welding when the use of
filler material, but this method is easy to cause a lot of waste and
resource-consuming labor. A more convenient way to deal with a major problem is
the thermal cracking technology will solve.
5 Conclusion
Speed laser
welding of aluminum alloys there are a lot of advantages in a variety of
manufacturing fields has been widely used, but also improve the quality of the
machine itself and the manufacturing speed, but laser welding technology also
has many flaws, resulting in failure of welding, I believe in the continuous
efforts of scientists, the welding technology will be more mature, more and
more widely.
