FIELD OF INVENTION:

The Present invention relates to an improved shielding gas nozzle for MAG torch assembly for panel welding machine.
More particularly the invention relates nozzle assembly consisting of gas nozzle, contact tip holder cum diffuser and contact tips for MAG torch for panel welding machine which is used for boiler water panel manufacturing.
BACK GROUND OF THE INVENTION:
High pressure, high temperature steam generation used for thermal power generation normally consisting super heaters, re-heaters, evaporators and economizers, water wall panel etc. Normally all the said equipment’s are made up of tubes and pipes. Water wall panel is nothing but connection of tubes in series welded by fin in between tubes (refer Fig 1).
In the manufacturing of the water wall panel, it is a common practice to join the fins in-between the tubes by panel welding machine having metal active gas (MAG) welding process.
The present machine welding torch assembly shown the MAG torch assembly included existing gas nozzle (01, 02, and 03) where (01) represents existing nozzle main body and (02) represents the existing insulator inside the main body and (03) is the existing gas nozzle tightening ring (04) represents existing contact tip (05) represents contact tip holder cum gas diffuser with concentric consumable wire path (not shown) etc. Tip holder (05) is attached with welding torch body. Contact tip (04) is attached with contact tip holder cum gas diffuser (05). Existing gas nozzle main body (01) is the distal end of torch assembly which is near to the fins and tubes. Existing gas nozzle is made of main nozzle body (01), insulator (02) and tightening ring (03). Proper shielding gas is one of great

importance to get a sound welding performance. During the panel welding operation, MAG welding torch assembly is not kept perpendicular but in an angular position. There are sixty number of nozzles are used per month and 720 number of nozzles per annum. The quality of the shielding gas is found good but the flow is a problem.
During panel welding in the existing practice, contact tips are frequently to be changed. Since the removal of contact tips separately from contact tip holder cum diffuser is cumbersome, hence there is a need for developing an arrangement between contact tip and contact tip holder cum diffuser so that the tips can be taken out easily as well as maintaining a proper shielding gas flow.
OBJECTS OF THE INVENTION:
It is the object of the invention to develop an improved shielding gas nozzle for MAG torch assembly for panel welding machine.
Another objection of the invention is to develop an improved shielding gas nozzle for MAG torch assembly for panel welding machine that improves the quality of panel welding operation reducing the defects due to gas welding.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 shows panel welding comprising fins and tubes. Figure 2 shows Existing Gas nozzle (A1). Figure 3 shows Existing contact tips.
Figure 4 shows Existing contact tip holder cum gas diffuser (B1). Figure 5 shows Developed gas nozzle (C1). Figure 6 shows Developed contact tips.
Figure 7 shows Developed contact tip holder cum gas diffuser (D1). Figure 8 shows the difference in the constructional features of the existing and modified nozzle main body. (E1 and F1 respectively).

Figure 9 shows the assembly of all the modified components with corresponding item Nos indicated there on.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION:
Item 01: Existing gas nozzle main body (01).
MAG torch assembly included contact tip (04), contact tip holder cum gas diffuser (05),
with concentric consumable wire path etc.
Item 02: Existing Gas nozzle insulator (02). This act as barrier between the nozzle main body (01) and contact tip (04).
Item 03: Existing Gas nozzle tightening ring (03). Through this ring, the gas nozzle main body (01) is fitted with MAG Welding Torch (not shown).
Item 04: Existing contact tip (04). This contact tip (04) is having no thread. This is attached with contact tip holder cum diffuser (05) via push and fit method. During welding, in the existing setup contact tips are to be changed frequently. Removal of contact is very difficult and both the items (04 and 05) require replacement at frequent interval.
Item 05: Existing contact tip holder cum diffuser (05). This item (05) is fitted with welding torch via thread and with the other end attached with contact tips (04) via push and fit method in the bottom side.
Item 06: Developed gas nozzle comprising three-parts i.e. gas nozzle modified main body (01)M, insulator modified (02)M and tightening ring modified (03)M. Improved nozzle has been shown in (Figure 8) with main body (01)M which provides smooth flow of shielding gas by removing the step inside in the existing item (01). Overall length and diameter of the improved nozzle body (01)M has been changed.
Item 02M: Developed insulator (02)M.

Item 03M: Developed tightening ring (03)M.
Item 04M: Developed contact tip (04)M is fitted with tip holder (05)M via thread instead of push and fit and overall length is also increased. Due to the threading arrangement in contact tip (04) the removal of contact tip (04)M from tip holder (05)M has become easy in case of replacement of contact tips during welding process. Earlier both contact tip (04) and tip holder cum diffuser (05) had to be removed simultaneously due to the difficulty in removal of contact tips (04) separately from tip holder (05) which is time consuming also. Now due to introduction of threading arrangement, removal of contact tips (04)M from tip holder (05)M is very easy with lesser time. The longer length of contact tips provides more gripping area for replacement.
Contact tip holder cum diffuser (05)M: This item (05)M is fitted with contact tips (04)M via thread. Due to this thread fitting, removal of contact tips (04)M separately from tip holder (05)M is very simple and easy for machine operator as compared to the earlier practice.
Because of the step involved in the inside of existing nozzle (01), the shielding was not proper and the shielding gas flow is also turbulence. In addition to the changes in the length and diameter of the nozzle, the step existed earlier in the main body (01) was removed. A continuous taper is now provided in the developed gas nozzle body (01)M which has resulted in excellent shielding of gas, thereby increasing the efficiency of shielding. Even though the angle of the torch to the panel remains same comparing with the existing one and because of the changes made in the design of the nozzle, the distance between the work piece (panel) and the nozzle tip is unaltered, the flow of shielding gas increase with lesser turbulence.
In the earlier assembly and because of non-availability of thread in contact tips (04), fitting and removal of contact tips (04) from tip holder cum diffuser (05) was cumbersome. With the introduction of thread in contact tip (04)M and along with the changes in shape and dimension of the contact tips (04)M, removal of contact tips has become simple and easier comparing the prior art. Thereby there is a substantial saving in time in the process time which increases the productivity.

The improvement made in the exiting tip holder cum diffuser (05), having internal thread are illustrated in figure 7. This facilitates the removal of contact tips (04)M during operation and for maintenance purpose Increase in length of contact tip (04)M ensures the increase in area of contact of the consumable wire (not shown) which has resulted in current rating for better weldment. Since the overall length increased, the length of the tip holder cum diffuser (05)M is correspondingly decreased.
The complete assembly has been shown in Figure 9 in sectional view with indicating the modified items there on as G!:
Contact tip holder cum diffuser (05)M having upper thread to connect it with welding torch (now shown). Item (05)M is also having bottom thread to connect it with contact tip (04)M. Insulator (02)M is inserted concentrically from top to place it in-between the nozzle body (01)M tapered end and contact tip cum diffuser (05)M. Nozzle (01)M is connected to the welding torch (not shown) through gas nozzle tightening ring (03)M. All the items are assembled concentrically.

WE CLAIM
An improved shielding gas nozzle for MAG assembly for panel welding machine comprising:
a gas nozzle body (01)M, the said nozzle body having a uniform taper in the tip end and on the other end fixed with a tightening ring (03)M for connecting the nozzle body (01)M with a MAG welding torch;
a gas nozzle insulator (02)M fitted concentrically inside the nozzle body (01)M which acts as a barrier between the nozzle body (01)M and a contact tip (04)M, the said modified contact tip (04)M disposed inside the nozzle body (01) M and connected at top end with a tip holder cum diffuser (05)M by a threading arrangement at a first end, whereas the other end of tip holder cum diffuser (05) M connected to a welding torch body;
the contact tip (04)M having a central passage of shielding gas wherein the bottom end of conduct tip (04)M is near to the nozzle body (01)M tip, characterized in that the shielding gas after flowing through the holes of diffuser (05) on and then through the nozzle body is impinged on the welding region flowing smoothly without any turbulence providing excellent sealing during welding process in the manufacturing of panels.