CROSS REFERENCE
The present invention is a Patent of addition of the Indian Patent No 247481.
FIELD OF INVENTION
The invention generally relates to Strip-Electrode Gas Metal Arc Welding (SEGMAW). More particularly, the invention relates to an improved welding torch for "Strip-electrode Gas Metal Arc Welding". The invention further relates to an improved strip electrode gas metal arc welding system.
BACKGROUND OF THE INVENTION
There has been a continuous demand for newer welding processes and techniques with improved productivity, better quality in order to bring down the cost of welding. It was demands such as these, which prompted the development of high-performance welding processes with enhanced wire feed speeds and deposition rates. A process is regarded as a "high-performance" welding process if it achieves a deposition rate more than 8 kg/h.
"Tandem" MIG welding is one such high performance MIG welding technique developed to achieve higher productivity. It involves feeding of two electrode wires through the same torch, creating two arcs acting on the same weld pool and melting off simultaneously. Though tandem MIG gives higher deposition rate and welding speed, there are problems with guiding the torch along curved welding seams, as the geometrical relative positions of the leading and trailing wires have to be maintained with respect to the direction of welding.

A new approach to boost the performance of GMA welding is to use flat strip-wires, with which higher deposition rates comparable to that of tandem MIG can be achieved. The advantages of strip electrode GMA welding over tandem welding are, firstly, that only one power source is needed, and secondly, it is considerably easier to set the welding parameters.
Strip-wire electrodes are produced either by additional rolling of round wires, or by slitting wide strips. Rolled strip-wires have rounded edges, while slit strip-wires tend to be sharp-edged. From the wire feed point of view, then, rolled strip-wires are preferable.
However, winding the strip electrode on standard welding spool is quite difficult and feeding of the strip-wire electrode causes problems due to twisting of strips. Therefore, it would be desirable if the standard MIG welding wire is converted into continuous strip online and is fed through an improved welding torch. Such a development shall eliminate the need for winding the strip wire on the spool. An improved torch must be capable for feeding strip electrode. Additionally, it will be necessary to develop a corresponding gun and contact tip for accommodating the strip electrode wire.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved welding torch capable of accommodating strip electrode wire, which eliminates the disadvantages in prior art strip - electrode gas metal arc welding technique.

Another object of the invention is to propose an improved welding torch, which is capable for consistent transfer of the current to the strip
electrode wire.
A further object of the invention is to propose a strip electrode gas metal arc welding system which is capable of converting online the MIG welding wire to continuous strip for feeding into the improved welding torch.
These and other objects and advantages of the invention will be apparent from the ensuing description.
At the outset of the description, which follows, it is to be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only an exemplary embodiment and the teachings of the invention are not intended to be taken restrictively.
SUMMARY OF THE INVENTION
Accordingly, in a first aspect of the invention there is provided an improved strip electrode gas metal arc welding system for providing higher deposition rate, improved gap bridging capability, higher welding speed and better weld quality, the improvement is characterized by comprising; a guide tube for feeding a standard MIG welding wire; a rolling - cum - feeding means for converting the standard MIG welding wire to a flat strip being fed through an improved torch via a contact tube; and a constant voltage type power source with reverse polarity connection.
In a second aspect of the invention, there is provided an improved torch adaptable in a strip electrode gas metal arc welding system, comprising; a torch body for guiding the gas flow, the body housing at least two strip-

wire guide tubes, a gas cup being screwably attached to the torch body; a contact tip holder including a contact tip cap and split contact caps, the contact tip cap allowing feeding of the strip electrode, a stable arc being produced to provide a good weld beat, with higher deposition rate at a higher welding speed.
In a second aspect of the invention, there is provided an improved torch adaptable in a strip electrode gas metal arc welding system, comprising; a torch body for guiding the gas flow, the body housing at least two strip-wire guide tubes, a gas cup being screwably attached to the torch body; a contact tip holder including a contact tip cap and split contact caps, the contact tip cap allowing feeding of the strip electrode, a stable arc being produced to provide a good weld beat with higher deposition rate at a higher welding speed.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - shows an embodiment of the apparatus according to the invention.
Figure 2 - shows an improved welding torch according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views.
Figl shows the schematic of the Strip Electrode Gas Metal Arc Welding system. In this system, a standard MIG welding wire (1) available in 300 mm diameter spool (2) is fed through a guide tube (3) and then it is converted into a flat strip (4) by a rolling cum feeding means (5). The flat

strip (4) thus formed is fed through a torch (6). The torch (6) incorporates
a contact tube (7) to allow feeding of the strip electrode (4). A standard
Constant Voltage type power source (8) is used with reverse polarity
connection.
The welding system converts a standard 1.6 mm diameter MIG wire into
a flat strip (4) and feeds the strip (4) through the torch (6). A contact tube
(7) has been configured to allow feeding of strip electrode (4).
As shown in fig - 2, the welding torch of the invention comprises a torch body (11) which houses atleast two strip-wire guide tubes (10, 13), and having a contact tip holder (14), a contact tip cap (15) and a split contact tips (16).
A gas cup (12) is screwed on to the body (11) for guiding the gas flow. The shielding gas is supplied through an inlet nipple (9) of the torch (6).
The advantages of the invention can be seen, inter alia, in the fact that the strip electrode wire (4) is fed smoothly through the modified contact tube (15) and a stable arc is produced resulting in good weld bead at higher welding speed and deposition rate. The novel system provides higher deposition rate, improved gap bridging capability, higher welding Speed and better weld quality.

WE CLAIM;
1. An improved strip electrode gas metal arc welding system for
providing higher deposition rate, improved gap bridging capability,
higher welding speed and better weld quality, the improvement is
characterized by comprising;
- a guide tube (3) for feeding a standard MIG welding wire (1);
- a rolling - cum - feeding means (5) for converting the standard MIG welding wire (1) to a flat strip (4), being fed through an improved torch (6) via a contact tube (7); and
- a constant voltage type power source (8) with reverse polarity connection.
2. An improved torch adaptable in a strip electrode gas metal arc
welding system, comprising;
- a torch body (11) for guiding the gas flow, the body (11) housing
at least two strip-wire guide tubes (10, 13), a gas cup (12) being
screwably attached to the torch body (11);
- a contact tip holder (14) including a contact tip cap (15) and
split contact caps (16), the contact tip cap (15) allowing feeding
of the strip electrode (4), a stable arc being produced to provide
a good weld beat with higher deposition rate at a higher welding
speed.