24
S. K. Das et al.
hence unacceptable. Thus, some special arrangement has been devised to eliminate
this problem.
Designing a Wedge to Transfer the Hole
This has been one of the preferred ways of getting rid of ejection hole in case of pipe
welding. In this case, an extra wedge block is attached by temporary means to the
pipe preferably at the starting point of the weld track (refer Fig. 1.11a). Now, once the
welding is complete and the tool again gets to the starting point, a tangential motion
is given to the tool which makes it gradually shift to the attached block, thus leaving
the ejection hole on the wedge rather than the pipe. The attachment is then removed
by hammering or minor machining. A zoomed view of the wedge connected to the
pipe is illustrated in Fig. 1.11b.
Retractable Pin Configuration
In fixed pin configuration, the FSW tool is a single unit consisting of the shoulder
and the pin. This is the most common tool used in FSW and is the most easiest to
manage from control perspective. But nevertheless, there is no choice but to have
an exit hole when using this tool. Thus, researchers have come up with a retractable
pin type tool in which the pin and the shoulder are assembled as separate units
and arrangement is made such that the pin can move relative to the shoulder (refer
Fig. 1.12). The advantage with this modified tool is that it can be used for multidepth welding of workpieces [1, 71]. This is particularly useful when the thickness
of the workpiece is not very precise. In those circumstances, the distance of the back
surface of the weld to the tip of the pin can be maintained even though the shoulder
remains on the part surface. Additionally, retractable pin type tool can be used to
close the exit hole. However, the use of such tool makes the system complex with
additional considerations in the control schema.
1.6.3 Some of the Distinct FSW Setups Used Around
the World
Apart from the FSW setups discussed previously, there are various setups developed
for use in specific applications around the world. Some of the notable equipment
currently in use is described below [71]:
S. K. Das et al.
hence unacceptable. Thus, some special arrangement has been devised to eliminate
this problem.
Designing a Wedge to Transfer the Hole
This has been one of the preferred ways of getting rid of ejection hole in case of pipe
welding. In this case, an extra wedge block is attached by temporary means to the
pipe preferably at the starting point of the weld track (refer Fig. 1.11a). Now, once the
welding is complete and the tool again gets to the starting point, a tangential motion
is given to the tool which makes it gradually shift to the attached block, thus leaving
the ejection hole on the wedge rather than the pipe. The attachment is then removed
by hammering or minor machining. A zoomed view of the wedge connected to the
pipe is illustrated in Fig. 1.11b.
Retractable Pin Configuration
In fixed pin configuration, the FSW tool is a single unit consisting of the shoulder
and the pin. This is the most common tool used in FSW and is the most easiest to
manage from control perspective. But nevertheless, there is no choice but to have
an exit hole when using this tool. Thus, researchers have come up with a retractable
pin type tool in which the pin and the shoulder are assembled as separate units
and arrangement is made such that the pin can move relative to the shoulder (refer
Fig. 1.12). The advantage with this modified tool is that it can be used for multidepth welding of workpieces [1, 71]. This is particularly useful when the thickness
of the workpiece is not very precise. In those circumstances, the distance of the back
surface of the weld to the tip of the pin can be maintained even though the shoulder
remains on the part surface. Additionally, retractable pin type tool can be used to
close the exit hole. However, the use of such tool makes the system complex with
additional considerations in the control schema.
1.6.3 Some of the Distinct FSW Setups Used Around
the World
Apart from the FSW setups discussed previously, there are various setups developed
for use in specific applications around the world. Some of the notable equipment
currently in use is described below [71]: