FIELD OF THE INVENTION
The invention relates to an apparatus for manipulation and control of a narrow
gap torch for submerged arc welding process.
BACKGROUND OF THE INVENTION
Joining of high thickness components are best done using submerged arc
welding. It involves using narrow grooves demanding customized torch designs.
A special type of torch designed for such high thickness applications is the
narrow gap torch. This enables the arc movement of the torch through a narrow
bead and demands mechanization for finer control. Therefore, a mechanized
form of torch movement may allow the torch to navigate through the gap
without touching the side wall and also enable the weld deposit to be made in
the required dimensions.
Indian Patent No.216941 granted (March 2008) titled "An improved torch
assembly for narrow gap welding using single and tandem wire techniques in
submerged arc welding" discusses an improved torch assembly for narrow gap
welding using single and tandem wire techniques in submerged arc welding. It
comprises a torch holder fitted to the wire feeder at the top end and to a torch
positioner at the bottom and fixed with a lock nut for a support of pivotal
movement transverse to the welding direction, said positioner has a nozzle at the
lower end and said assembly of positioner and the torch holder is provided with
a tilting means comprising a tilting frame mounted on an adjustable screw with a
handle.

Indian Patent 218881 granted (April 2008) titled "Method for welding railroad
rails" discusses a method and system for automatically filing the narrow gap
between facing end walls of adjacent first and second railway rails by depositing
vertically spaced layers of molten metal in the gap with an electric arc welding
torch using a robotic mechanism. This however is not related to the design of
controller for narrow gap torch or the assembly.
Indian Patent 248111 granted (June 2011) titled "A device for configurating and
feeding a uniformly bent Wire with a preset pitch and amplitude to oscillate a
welding arc in Narrow Gap Gas Metal Arc Welding procedure" discusses a
compact device for producing and feeding uniformly bent wire for oscillating the
arc in narrow gap gas metal arc welding procedure, the device comprising a wire
spool accommodating a continuous straight wire. A wire-feeder drawing the wire
from the wire-spool via a wire- guide for feeding the wire into a wire-bending
means, the wire-bending means configuring the fed wire into a sinusoidal wave
form.
United States Patent 6596969 dated July 22, 2003 (Sakurai et.al.,), PCT
No.W000/54923, titled "Method for guiding arc laser and arc guiding welding and
device by the method" discusses in an arc welding method and apparatus, a
plasma is generated at a welding intended position on a base material by a laser
irradiated to the base material. This patent however does not relate to the SAW
process or design of controller for arc welding processes.

United States Patent 4,59,1685 dated May 27, 1986 (Hinger et al.) tilted "Narrow
gap welding torch" discusses a narrow gap welding torch using a twisted wire
center electrode.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose an apparatus for
manipulation and control of narrow gap torch submersible arc welding process.
Another object of the present invention is to propose an apparatus for
manipulation and control of narrow gap torch submersible arc welding process
which enables butt jointing of different materials reducing the cycle time.
A still another object of the present invention is to propose an apparatus for
manipulation and control of narrow gap torch for submersible arc welding
process which provides a mechanized control of the narrow gap torch with a
limited movement.
SUMMARY OF THE INVENTION
Accordingly, there is provided an apparatus for manipulation and control of
narrow gap torch in a submersible arc welding process comprising a mounting
assembly having a worm gear and a torch head assembly, the torch assembly
including a flexible arrangement for housing the narrow gap torch in a fixed
position, and a controller for controlling the movement of the torch with the
welding groove ± 3°.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 - A schematic representation of an apparatus for manipulation and
control of narrow gap torch for saw process according to the invention.
As shown in figure 1, an apparatus for manipulation and control of narrow gap
torch is disclosed. The apparatus comprises a DC motor (1) which has sufficient
torque to support the load of wire feeder, the torch head assembly the torch.
The torch head assembly includes a housing arrangement for the narrow gap
torch (2) with torch mounting assembly (5). The torch head is connected to the
DC motor though worm gear (3) driving the narrow gap torch. The position of
the torch is sensed by the encoder (4) and is sent to the controller. The signal
from the encoder is used in conjunction with the limit switches (6) to limit the
movement of the torch to ± 3°. The limit switches will cut off the supply to the
DC motor from driving the torch any further.

WE CLAIM:
1. An apparatus for manipulation and control of narrow gap torch in a
submersible arc welding process comprising a mounting assembly
having a worm gear and a torch head assembly, the torch assembly
including a flexible arrangement for housing the narrow gap torch in a
fixed position, and a controller for controlling the movement of the
torch with the welding groove ± 3°.
2. An apparatus as claimed in claim 1, wherein current position of the
torch is measured by a sensor/encoder, and wherein the positional
data of the torch is conveyed as a digital signal through the encoder.
3. An apparatus as claimed in claim 1, comprising a plurality of limit
switches for starting and stopping the movement of the narrow gap
torch, the controller transmitting the signal to the limit switches to
move or to stop the torch.
4. An apparatus as claimed in claim 1, wherein the narrow gap torch is
connect5ed to a DC motor and the encoder.

5. An apparatus as claimed in claim 1, wherein the controller compares
the position of the torch from the encoder signal with a pre-stored
data and initiates an ON/OFF action to the limit switch for control of
the torch position.

ABSTRACT

The invention relates to an apparatus for manipulation and control of
the movement of the narrow gap torch to an extent of ±3°. Joining of
high thickness components is done using SAW process. Different joint
designs used in the SAW process demand different torch designs for
optimal utilization. A narrow gap torch therefore has to negotiate a
very small space in the welding groove and has to be controlled
through an external controller. Hence, an apparatus to measure the
current position, generate the signal for the movement of the torch
through the groove. The movement of the torch is controlled by limit
switches on either side of the torch. Thus, the controller provides an
option to mechanize the torch assembly for SAW process.