FORM 2
THE PATENT ACT, 1970
(39 of 1970)
&
THE PATENTES RULES, 2005
COMPLETE SPECIFICATION (See section 10, rule 13)
1. TITLE OF THE INVENTION
"PORTABLE WELDING GUN WITH ROLLER GUIDE"
2. APPLICANT(S)
(a) Name : MAHINDRA & MAHINDRA LIMITED
(b) Nationality : Indian Company registered under the provisions
of the Companies Act, 1956
(c) Address : R&D Center, Automotive Sector,
89, M.I.D.C., Satpur, NASHIK - 422 007 Maharashtra State, India
3. PREAMBLE OF THE DESCRIPTION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Portable welding Gun with Roller Guide
Field of Invention
The present invention is related to the portable spot welding gun. More particularly, the present invention is related to the roller guide attached to the welding gun to guide the gun in a particular direction.
Background of the Invention
The portable spot welding gun is widely used for resistance welding of sheet metal parts in automobile industry. As per the vehicle body design, it is sometime required to locate the portable spot welding equipment on intricate areas.
In manual operation, if operator fails to place the gun on correct location, it causes defect of damage or hole on sheet metal part. It is frequent while welding on intricate shapes/ areas. If operator does a mistake it causes damage/ indentation on skin surface (visible to customer) of body-shell.
To avoid this and to locate the portable spot welding gun properly on intricate areas. and to prevent the defect due to dislocation of portable spot welding equipment, conventionally, the fixed guides/ stoppers are installed on fixture or detachable guide is placed on sheet metal parts assembly. Such guides can not be provided on intricate portions. Manual guides/stoppers positioned externally has high wear rate also time consumed in placing/ removing such guides/ stoppers result in non value addition. Also, if operator did not position it well or he forgets to place it, then it results in defect.
Prior Art
European patent no. EP1221351 and Korean patent application No. KR20020046201 discloses weld gun with inverted roller screw actuator. The welding gun for performing a welding operation on a work piece comprises a pair of opposing arms movable relative to each other to apply pressure to the work piece

during a welding operation; and an inverted roller screw linear actuator for moving the opposing arms relative to each other, wherein the inverted roller screw linear actuator further comprises an elongate shaft having a first end for connection to one of the opposing arms and a threaded portion opposite from the first end; a rotatable body having threaded race formed thereon for engaging a plurality of roller bearings interposed between the race and the threaded portion of the elongate shaft to translate the elongate shaft in either linear direction in response to rotation of the body in either rotational direction; and a rotary motor for rotating the body in either rotational direction, and the weld gun further comprises an interchangeable electrode cap connected to an end of each arm in opposition to one another for movement between an open position spaced from one another to a closed position capturing a work piece there between for welding; and means for selectively retaining the electrode cap on each arm.
Another Korean patent application no. KR200100001268 describes foot spot welding machine with panel guide structure to enhance welding efficiency by making welding convenient. A mobile welding gun installed on a fixed welding gun to move up and down by foot manipulation of a worker pressurizes a panel to weld. Herein a panel guide guiding the side and lower face of the panel between the fixed welding gun and the mobile welding gun along the horizontal movement direction are prepared. The panel guide comprises a guide block fixed on the fixed welding gun, a side guide roller supporting the side of the panel and a lower guide roller supporting the lower face of the panel.
None of the prior art educates about a welding machine that assists in locating the electrodes of portable welding gun on intricate areas such as flange, and the like.
Objects of the Invention
The main object of the present invention is to provide a portable welding gun with guiding mechanism, which enables to locate electrodes of portable spot welding gun on intricate areas of an automotive body.

Another object of the present invention is to provide a portable welding gun with guiding mechanism, which is capable of preventing defect of damage or spot hole on skin part of sheet metal panel of the automotive body-shell.
Further object of the present invention is to provide a portable welding gun with guiding mechanism, which also overcomes the drawbacks of prior art dampers for automotive suspension system.
Statement of the Invention
According to the present invention there is provided a portable welding gun with guiding mechanism, the portable gun comprising:
a fixed gun arm extending from a body of the portable welding gun, the fixed gun arm enables to dispose the portable welding gun over sheets to be welded, the fixed gun arm
a fixed shank and a gun cap tip;
a reciprocating gun arm reciprocatably secured to the body, the reciprocating gun arm capable of welding the sheets upon moving towards the fixed gun arm, characterized in that, the guiding mechanism comprises,
a block secured over the fixed gun arm; and
a roller rotatably pinned to the block at a pre-defined distance with axis parallel to the gun cap tip.
Typically, wherein the fixed arm is an electrode.
Typically, wherein the reciprocating arm is an electrode.
Typically, wherein the block is made of nylon.
Typically, wherein the roller is made of copper chromium alloy.

Brief Description of the Drawings
The objects and features of the present invention will be more clearly understood from the following description of the invention taken in conjunction with the accompanying drawings, in which,
Figure I shows welding gun with roller guide in accordance with the present invention; and
Figure 2 shows exploded view of roller guide attached to the welding gun as per the present invention.
Detail Description of the invention
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides a guiding mechanism for guiding a portable welding gun. The guiding mechanism enables locating electrodes of portable spot welding gun on intricate areas of an automotive body. Further, the guiding mechanism is capable of preventing defect of damage or spot hole on skin part of sheet metal panel of the automotive body-shell.
This present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.
Referring now to Fig, 1 & 2 various views of a portable welding gun (herein after referred as "gun (100)") with guiding mechanism used for spot welding are illustrated. The gun (100) includes a body (10), a fixed arm (20), and a reciprocating arm (30). The fixed arm (20) extends from the body (10) and is curved to accommodate a portion of metal sheets to be welded therein. The fixed arm (20) includes a fixed shank (22) and a gun cup tip (24). The fixed arm (20) is extended to

configure the fixed shank (22), and the gun cup tip (24) is on an end portion of the fixed shank (22). The portion of metal sheets to be welded is rested against the gun cup tip (24).
Further, reciprocating arm (30) extends straight and in axial alignment with the gun cap tip (24), so that the metal sheets are welded. Upon activating the gun (100) for welding, the reciprocating arm moves toward the gun cap tip (24) for welding metal sheets held there between. The fixed arm (20) and the reciprocating arm (30) are electrodes.
Referring again to figures 1 and 2, the improvement comprises a guiding mechanism (90) having a block (40), and a roller (50) is illustrated. The block (40) is secured to the fixed arm (20). In an embodiment the block (40) is made of nylon. The roller (50) is pinned to the block (40) at a pre-defined distance with axis parallel to the gun cap tip (24). The distance between the gun cap tip (24) and the roller (50), is adjusted in a manner that the roller (50) rolls over seam of the metal sheets to guide the fixed arm (20) thereover, thereby avoiding frequent adjustment of the gun (100) with respect to the metal sheets on the intricate area at the desired spot accurately. In an embodiment, the roller (50) is pinned by pin (52) with the block (40). In one embodiment, the roller (50) is made of copper chromium alloy. The roller (50) restricted the gun electrode entry on skin surface. Further, the roller (50) provides a zero resistance while shifting the gun (100). The roller (50) made of copper alloy dose not allow weld spatters to get deposited thereon.
The present invention of portable welding gun (100) with roller guide provides following advantages:
Uniform welding over the intricate area of automotive body surface is
achieved.
Efficiency of welding operation is improved.
- No specifically skilled workers are required to perform the operation.
- The guide mechanism (90) can be attached to any portable welding gun with ease.
- Mistakes in manual welding operation are almost eliminated / minimized.

Improves the performance of human operator with perfection. - Mental drudgery and fatigue involved in the operation is reduced.
It should be understood that the present invention is not to be limited by the exact details of the illustrated embodiment. However, it is to be taken as the preferred example of the invention and that various changes may be resorted to by a person skilled in the art without departing from the spirit of the invention or the scope of below mentioned claims. Also, the terminologies used herein are for the purpose of description and should not be regarded as limiting.

We Claim:
1. A portable welding gun with guiding mechanism, the portable gun
comprising:
a fixed gun arm extending from a body of the portable welding gun, the fixed gun arm enables to dispose the portable welding gun over sheets to be welded, the fixed gun arm
a fixed shank and a gun cap tip;
a reciprocating gun arm reciprocatably secured to the body, the reciprocating gun arm capable of welding the sheets upon moving towards the fixed gun arm, characterized in that, the guiding mechanism comprises,
a block secured over the fixed gun arm; and
a roller rotatably pinned to the block at a pre-defined distance with axis parallel to the gun cap tip.
2. The portable welding gun as claimed in claimed 1, wherein the fixed arm is an electrode.
3. The portable welding gun as claimed in claimed 1, wherein the reciprocating arm is an electrode.
4. The portable welding gun as claimed in claimed I, wherein the block is made of nylon.
5. The portable welding gun as claimed in claimed ], wherein the roller is made
of copper chromium alloy.