FIELD OF THE INVENTION
The present invention relates to an apparatus and an welding process for joining
a stub to a header involving similar/dissimilar materials. More particularly the
invention relates to an orbital type apparatus with cam device supported by a
laser vision sensor based seam tracking means for welding of a stub to a header
in a boiler system.
BACKGROUND OF THE INVENTION
Joining of stub to header components can be done directly by fusion welding. An
apparatus of orbital system with cam arrangement and a sensor based seam
tracking system for GMAW or SAW process are normally used for mass
production in boiler industry. The GMAW and SAW welding being an
automated/semi automated process achieve high productivity due to its less
cycle time as compared to other SMAW welding process. Thus, the GMAW and
SAW welding process is more effective for joining of stub to header, valves, and
other similar jobs.
According to the prior art, stub to header welding joint of carbon steel to carbon
steel material is done by SMAW process but the cycle time is quite long and the

productivity is less. The weld exhibits defects like slag inclusion, cracks, under-
cut. In macro structure, the heat affected zone is found to be higher.
The economy of a welding process is largely estimated by a factor namely, cycle
time reduction, which constitutes a difference of the length of a work piece
before and after the welding process. In order to maintain economy of the
process, it is important to maintain the defect free welds as low as possible,
which requires to first determine the effects of important parameters on weld
parameters including an optimum condition to maintain the good quality welds.
United States Patent 7560662, B2dt, Amador et al discloses a method for using
equipment and process for applying an external structural weld to piping and
similarly shaped pressure boundary components especially for use in piping
fittings and nozzle welding for weld over lay in an structural applications.
According to this prior art method, an orbital welding equipment is adapted to
apply an external structural weld over lay on a nozzle section of a pressure
vessel having a hemispherical head.
United States Patent 4288020 dated 8 September 1981 to Sealers et al describes
a tracking type welding apparatus wherein a torch follows a probe along a weld
seam and the probe senses lateral seam deviations and stores the data in a pin
cam and wherein the deviations are later used to move the torch in the same
manner. The pin cam is remote from the torch including the probe assembly and
is electrically synchronized.

OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose an orbital type
apparatus with cam device supported by a laser vision sensor based seam
tracking means for welding of a stub to a header in a boiler system.
Another object of the present invention is to propose an orbital type apparatus
with cam device supported by a laser vision sensor based seam tracking means
for welding of a stub to a header in a boiler system which is enabled to produce
butt joint of different materials in different welding processes, and reduces the
cycle time.
A still another object of the invention is to propose an orbital type apparatus with
cam device supported by a laser vision sensor based seam tracking means for
welding of a stub to a header in a boiler system which provides weld-chemistry
of the weld according to the highest code quality.

SUMMARY OF THE INVENTION
Accordingly, there is provided an orbital type apparatus with cam device
supported by a laser vision sensor based seam tracking means for welding of a
stub to a header in a boiler system in the inventive apparatus of orbital system
with cam arrangement and an seam tracking system welded joint according to
the invention, the heat affected zone is found to be substantially small, and
without any defects.
According to the invention the process is enabled to develop required mechanical
properties in the weld joints.
The two head assembly are constructed to undergo two head assembly are
constructed to undergo two simultaneous movement of 180°C each in
diametrically opposite direction to carry out orbital welding.
The apparatus allows welding of the similar/dissimilar material combination by
adapting SAW or GMAW welding process including joining of a fusion welding of
the stub to header shell in narrow grooves.
The header assembly includes a flexible arrangement with a long narrow groove
nozzle for welding of stub to header in thick section.
The sensor is fixed outside the groove to guide the torch to carry out the
welding.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 a schematic representation of an orbital type apparatus with cam
arrangement supported by a laser vision sensor based seam tracking means for
stub to header welding in a boiler system.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Figure 1 an apparatus for welding of stub to header welding of
complex configuration is disclosed. The apparatus comprises a mounting
assembly (4) having a cross slide and one each weld head assembly on both
sides i.e. (right and left). Each head assembly includes a flexible arrangement
with along narrow groove nozzle (5, 6) with controllable sensor based tracking
means. Each had assembly further includes a plurality of orbital weld head (3)for
welding a stub (2) to a header (1). This apparatus can be mounted easily on the
stub that may be operated in a smaller area of any narrow groove avoiding
operating interferences.

WE CLAIM :
1. An orbital type apparatus with cam device supported by a laser vision
sensor based seam tracking means for welding of a stub to a header in a
boiler system, the apparatus comprising a mounting assembly (4) having
a cross slide and one each weld head assembly on both sides i.e. (right
and left). Each head assembly includes a flexible arrangement with a long
narrow groove nozzle (5, 6) with controllable sensor based tracking means
(7). Each head assembly further includes a plurality of orbital weld head
(3) for welding a stub (2) to a header (1), wherein the two head
assemblies are simultaneously operable at 180° each in opposite
directions to carry out the orbital welding, and wherein the sensor is fixed
outside the narrow groove to guide the torch for carrying out welding.

ABSTRACT

The invention relates to an orbital type apparatus with cam device supported by
a laser vision sensor based seam tracking means for welding of a stub to a
header in a boiler system, the apparatus comprising a mounting assembly (4)
having a cross slide and one each weld head assembly on both sides i.e. (right
and left). Each head assembly includes a flexible arrangement with a long
narrow groove nozzle (5, 6) with controllable sensor based tracking means (7).
Each head assembly further includes a plurality of orbital weld head (3) for
welding a stub (2) to a header (1), wherein the two head assemblies are
simultaneously operable at 180° each in opposite directions to carry out the
orbital welding, and wherein the sensor is fixed outside the narrow groove to
guide the torch for carrying out welding.