10 A Novel High-Efficiency Keyhole Tungsten Inert Gas …
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good weld with a high productivity compared with submerged arc, MAG welding or
some other conventional welding method [6] performed single-pass welding of AISI
304, including 12 mm plate at 300 mm/min, 8 mm plate at 500 mm/min and 3 mm
plate at 1000 mm/min.
The formation of the keyhole is caused by the high pressure under the arc centre,
which is similar to the recoil pressure discovered in the LBW and EBW [7–9], but
for a great portion that this pressure owes to the mechanical impact of the PAW jet.
Some trails of keyhole TIG welding were conducted by Norrish using improved TIG
device to realize TIG welding with dual gas [10].
K-TIG welding has a lot of advantages. First, joints can be completed in just one
pass without filling wires of metal as well as edge preparations. Second, it can be
applied to many kinds of materials including steel and titanium alloy. Compared with
other keyhole mode welding methods, the cost of the equipment is small because it
is a variant of GMAW, and the equipment is similar. Moreover, it can achieve full
penetration of the thick plates welding, and the welding quality is better than GTAW.
10.1.3 Equipment of K-TIG Welding
The commercial devices for high-current GTAW can be used for K-TIG welding.
The whole welding system includes a DC constant current power source and a
water-cooling welding torch. The welding process is usually performed automatically because the torch electrode is set to at a negative potential with respect to the
weldment.
The continuous using of the K-TIG torches over 1000 amps is guaranteed by the
design of the water cooling including protective cover of the torch and the shielding
mask. The entire process of getting cool within the torch is essential for keeping
a stable arc with different welding current, because of the continuous temperature
change over different places on the torch electrodes. Fan designed a new watercooling system, which not only includes water-cooling channel inside the torch but
also under the weldment [11]. This strategy is proved to reduce the volume of the
welding pool, as shown in Fig. 10.1.
10.1.4 HDR Imaging of K-TIG Welding
There are many parameters that can reflect the welding condition. The monitoring of
these parameters does help to the adjustment during the process as well as ensuring
the welding quality. Novel technology can be introduced in the observation of the
keyhole behaviour. High-dynamic range imaging was used in the measurement of the
entrance of the keyhole geometry [12]. First, the relationship between the radiance
of the K-TIG welding scene in reality and the pixel value is measured and described
as a response function. The distribution of the radiance in a high dynamic was then
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good weld with a high productivity compared with submerged arc, MAG welding or
some other conventional welding method [6] performed single-pass welding of AISI
304, including 12 mm plate at 300 mm/min, 8 mm plate at 500 mm/min and 3 mm
plate at 1000 mm/min.
The formation of the keyhole is caused by the high pressure under the arc centre,
which is similar to the recoil pressure discovered in the LBW and EBW [7–9], but
for a great portion that this pressure owes to the mechanical impact of the PAW jet.
Some trails of keyhole TIG welding were conducted by Norrish using improved TIG
device to realize TIG welding with dual gas [10].
K-TIG welding has a lot of advantages. First, joints can be completed in just one
pass without filling wires of metal as well as edge preparations. Second, it can be
applied to many kinds of materials including steel and titanium alloy. Compared with
other keyhole mode welding methods, the cost of the equipment is small because it
is a variant of GMAW, and the equipment is similar. Moreover, it can achieve full
penetration of the thick plates welding, and the welding quality is better than GTAW.
10.1.3 Equipment of K-TIG Welding
The commercial devices for high-current GTAW can be used for K-TIG welding.
The whole welding system includes a DC constant current power source and a
water-cooling welding torch. The welding process is usually performed automatically because the torch electrode is set to at a negative potential with respect to the
weldment.
The continuous using of the K-TIG torches over 1000 amps is guaranteed by the
design of the water cooling including protective cover of the torch and the shielding
mask. The entire process of getting cool within the torch is essential for keeping
a stable arc with different welding current, because of the continuous temperature
change over different places on the torch electrodes. Fan designed a new watercooling system, which not only includes water-cooling channel inside the torch but
also under the weldment [11]. This strategy is proved to reduce the volume of the
welding pool, as shown in Fig. 10.1.
10.1.4 HDR Imaging of K-TIG Welding
There are many parameters that can reflect the welding condition. The monitoring of
these parameters does help to the adjustment during the process as well as ensuring
the welding quality. Novel technology can be introduced in the observation of the
keyhole behaviour. High-dynamic range imaging was used in the measurement of the
entrance of the keyhole geometry [12]. First, the relationship between the radiance
of the K-TIG welding scene in reality and the pixel value is measured and described
as a response function. The distribution of the radiance in a high dynamic was then