FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
Title:
MODULAR COMPACT STRUCTURE FOR CONDUCTING OFF-LINE TRIALS
OF THE SPOT WELDING GUN FIXTURES
Applicant: MAHINDRA & MAHINDRA LIMITED
GATEWAY BUILDING, APOLLO BUNDER,
MUMBAI - 400001,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to spot welding fixtures, particularly to spot welding fixture trials which can be spatially moved in all directions and more particularly to a compact spot welding fixture which is also easy to be 'dismantled and relocated to any new project.
BACKGROUND OF THE INVENTION
For any new large welding project during manufacturing, a spot welding gun suspending and moving structure is required to suspend spot welding guns thereon in the course of developing the spot welding gun fixture and while carrying out trials of such fixtures. Normally, this structure has to move along and transverse the cross-car (X and Y axis) direction. Conventionally, a four-column or four-leg structure is being used for suspending and moving spot welding guns located only within such 4-column or 4-leg structures.
DISADVANTAGES WITH THE PRIOR ART
At present, the available 4-column or 4-leg spot welding gun suspending and moving structures for conducting trials of the suitability of such structures are bulky in size, yet offer very little space around it for the movement of the spot welding gun. In fact, any such structure must facilitate providing more space and the ratio of its operating area versus the size thereof should be good to improve the efficiency of such trials.
Therefore, there is an existing need to make the structure for suspending and moving the spot welding gun very compact for conducting trials in any new project site, and still which allows a multidimensional movement thereof for substantially improving the ratio of the operational area versus the size of the structure, so that it does not occupy more space when not in use. Moreover, any such improved structure should also provide ease of portability, so as to quickly dismantle it from one trial site and to allow its installation at another trials site without wasting much time in such unproductive activities.

DESCRIPTION OF THE PRESENT INVENTION
Accordingly, a modular single-column structure is developed for suspending IT (integral transformer) spot welding guns thereon. This modular construction allows its quick dismantling and storage within a comparatively much lesser space as compared to the conventional structure described above. Further, the operating range is also substantially higher, i.e. of the order of up to 3.7 meters .of radius around it. Thus, the new structure covers much larger operational area, however with a more compact size thereof. The cost of this new structure is also very less due to its compact size and less number of constructional members required to make it. The installation and dismantling time is also very little, so moving it to another trial site is very efficient, e.g. consuming 35~40% of time as compared to the conventional structure.
OBJECTS OF THE INVENTION
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:
An object of the present invention is to provide a spot welding gun trial structure with an increased operational area to size ratio.
Another object of the present invention is to provide a cost-effective spot welding gun trial structure.
Still another object of the present invention is to provide a spot welding gun trial structure which is easy and quick to be dismantled and relocate to different sites.
Yet another object of the present invention is to provide a compact spot welding gun trial structure, which needs lesser number of overhead rails.

A further object of the present invention is to provide a spot welding gun trial structure, which also has water pump and water tanks for facilitating quick cooling of the spot welding gun on-site.
These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a modular compact structure for conducting off-line trials of the spot welding gun fixtures, the structure comprises:
- a base frame lockable on ground by means of anchor plates after on-site positioning of the structure;
- a plurality of caster wheel assembly;
- a single-column centrally disposed on the base frame;
- a water tank with flexible connection pipes for cooling spot welding gun arm;
- a horizontal member assembly fixed on the central column for suspending a spot welding gun;
- a spot welding gun suspension means with spring balancer arrangement;
- a horizontal member support arrangement with bearings; and
- a control panel for controlling the spot welding cycle and for balancing the modular single-column structure;
wherein the control panel, water tank and water pump are supported on the base frame in order to counterbalance the weight of the horizontal member assembly and spring balancer counterbalances the spot welding gun weight.
Typically, the horizontal member assembly comprises a horizontal member fixed at the top of the central column between a pair of upper and lower brackets fixed thereon.

Typically, the horizontal member comprises a hinge pin welded at one end thereof, one end each of the hinge pin adapted to rotatably pivot the horizontal member between the upper and lower brackets via ball and thrust bearings respectively.
Typically, the horizontal member further comprises a rail section having a slot in lower edge thereof for moving the spot welding gun in desired spot welding position by means of a suspended wire and spring balancer arrangement.
Typically, the spring balancer arrangement comprises a gyro assembly attached to the rail section by means of a wire arrangement.
Typically, each of the plurality of caster wheel assembly comprises:
- a mounting plate fixed under the base frame of the structure;
- a U-bracket rotatably mounted under the mounting plate for facilitating a 360° rotation of the caster wheel thereunder; and
- a caster wheel with bearings.
Typically, a respective cover plate is provided in the upper and lower brackets for retaining the bearings within the brackets and for protecting from ingress of harmful foreign particles into the bearings.
Typically, at least one anchor plate is provided for fastening the modular compact structure to the ground by means of a plurality of anchor plates and a vertical slot is provided for adjusting the level difference between the ground and the base frame of the modular compact structure.
Typically, the water tank and control panel are mounted on the base frame in order to counterbalance the horizontal member assembly and the spot welding gun suspending therefrom.
Typically, the control panel controls and delivers the spot welding parameters as per the operational requirements and the targeted settings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will be briefly described with reference to the accompanying drawings, which include:
Figure 1 shows a perspective view of the conventional 4-column type structure for off-line spot welding gun trials on fixture;
Figure 2 shows a perspective view of the modular single-column structure in accordance with the present invention for off-line spot welding gun trials on fixtures;
Figure 3 shows a perspective detailed view of the modular single-column structure in accordance with the present invention as shown in figure 2;
Figure 4 shows the perspective view of the base of the modular single-column structure shown in Figure 3;
Figure 5 shows the perspective view of the center column of the modular single-column structure shown in Figure 3;
Figure 6a shows perspective view of the horizontal member of the modular single-column structure shown in Figure 3;
Figure 6b shows the perspective view of the rail mounted on the horizontal member shown in Figure 6a;
Figure 6c shows the perspective view of attaching the spring balancer to the rail shown in Figure 6b;
Figure 7a shows the perspective view of the upper bracket mounted on the center column of the modular single-column structure shown in Figure 3;
Figure 7b shows the perspective view of the lower bracket mounted on the center column of the modular single-column structure shown in Figure 3;

Figure 8 shows the perspective view of one of the caster wheels to cover ball bearings fitted on the caster wheels of the modular single-column structure shown in Figure 3;
Figure 9a shows the perspective view of the cap plate fitted on the base of the modular single-column structure shown in Figure 3;
Figure 9b shows the perspective view of the anchor plate fitted to the base of the modular single-column structure shown in Figure 3;
Figure 9c shows the perspective view of one of the water tank fitted (connected to a water pump, not shown here) on the base frame of the modular single-column structure shown in Figure 3;
Figure 10 shows the perspective view of the water pump for supplying water for cooling the spot welding gun.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.
Figure 1 shows a perspective view of the conventional structure 10 based on 4-columns 12 for suspending the spot welding gun 20 during their off-line trials and used for moving the spot welding gun 20 along and transverse to the car direction by means of the control panel 22. The structure 10 includes four columns 12 supporting a base 14 with necessary fittings 16, 18 for suspending the IT spot welding gun 20 during the off-line trials of spot welding structure 10 being developed for any new project. However, due to this 4-column structure, a large space is required for its storage and this substantially reduces the operational space available for doing such off-line structure trials. Moreover, this is a fixed structure not suitable for frequent dismantling and reinstallations at different locations. It also requires more

overhead rails, e.g. KBK rails along with corresponding runners and cross-tracker and their respective accessories. The operating range of this conventional structure is also very restricted, i.e. only the limited space enclosed within four columns 12. Therefore, its size to operating area ratio is very small and so manufacturing, installation and dismantling cost thereof are also very high. Further, there is no water tank and water pump provided for cooling the spot-welding guns in this structure 10.
Figure 2 shows a detailed perspective view of modular single-column structure 100 in accordance with the present invention provided for suspending spot welding gun 120 during their off-line trials and for moving such suspended integral transformer (IT) spot welding gun 120 in a three-dimensional car space. This new structure 100 has a compact construction and thus it offers substantially increased operational working space for spot welding fixture trials than the conventional 4-column structure shown in Figure 1. This structure occupies a very little space due to its modular single-column configuration. It also facilitates a broader 3-dimensional movement around the single column thereof (shown by arrows) and thus substantially increases the ratio of its operating area to the size. This modular configuration is also very easy to dismantle and suitable to be quickly reinstalled at different locations and for storing it in a much smaller space than the conventional 4-column structures. In fact, it requires just 35-40% of time as compared to the conventional structure shown in Fig. 1. Another advantage is the availability of a dedicated water tank 122 and water pump 136 for facilitating the cooling of the spot-welding gun 120. This new configuration also increases the operating range to approximately 3.7 meters radially around its single column 112. The modular structure 100 includes a single column 112 mounted on a base frame 114 that can be moved on caster wheels 116. Base frame 114 also supports a control panel 118 and a water tank 122 for cooling the spot welding gun 120 suspended by means of a wire 124 and a bracket 121 (Figure 9b) is used to fastening the structure 100 with ground by anchor bolts for safety purposes. A mechanical spring balancer 126 arrangement is mounted on the rail 128, which in turn is mounted on a horizontal member 130 fixed on the single column 112. The

member 130 is disposed between upper and lower brackets 132 and 134 respectively. The horizontal member 130 and rail 128 are mounted on this center column 112 via upper and lower brackets 132, 134.
Figure 3 shows another modular single-column structure 110, which is similar to that shown in figure 2. The only difference here is that the control panel 118 is mounted above the water tank 122 fitted on the base frame 114. Here as well, the control panel 118 is fitted on the centrally disposed vertical column 112. The main purpose of the control panel 118 is to control spot welding cycle and to balance the modular single-column structures 100, 110. A mechanical spring balancer 126 is suspended on the rail 128 by means of the arrangement of load trolley (not shown) to facilitate smooth sliding movement in the rail section 128. The spring balancer 126 is used to balance the weight of spot welding gun 120.
Figure 4 shows the perspective view of the base frame of the modular single-column structure 110 shown in Figure 3. The base frame 114 is a fabricated structure, on which the center column 112, water tank 122 and spot welding gun control panel 118 are all mounted. The water pump 136 is mounted on a stand 135. Normally, this base frame 114 is fabricated from ISMC 150X80 C-channel sections and other suitable metal plates and angles.
Figure 5 shows the perspective view of the center column 112 of the modular single-column structure shown in Figures 2 and 3. The center column 112 is centrally mounted on the base frame 114 and tightened with the help of a plurality of M16 nuts and bolts. The control panel 118 (Fig. 2) is fixed on members 113 provided on this center column 112. This center column 112 is configured to support a maximum overhang weight of 450 Kg in dynamic conditions.
Figure 6a shows perspective view of the horizontal member 130 of the modular single-column structure 100 and 110 shown in Figures 2 and 3. The horizontal member 130 is mounted on the centrally disposed vertical column

112. It has a hinge pin 130A welded at one end of member. The hinge pin 130A has an upper end 130aA and a lower end 130Ab for pivoting it between the upper and lower brackets 132, 134 respectively. The horizontal member 130 is normally made up of ISMB 150X80 T section 130B. This T section 130B is welded to hinge pin 130A by means of heavy reinforcements 130C. The bending strength of the horizontal member 130 is checked by using the simulation software (e.g. by Finite Element Analysis).
Figure 6b shows the perspective view of the rail section 128 mounted on the horizontal member 130 shown in Figure 6a. The rail 128, normally made of hexagonal section, is mounted on horizontal member 130. The rail 128 is used for moving spot welding IT gun 120 according the desired spot position by means of the arrangement of wire 124 and mechanical spring balancer 126 (Figs. 2, 3), which slides in a longitudinal slot 128A provided on the lower edge thereof.
Figure 6c shows the perspective view for attaching the spring balancer 126 (not shown here) suspender for spot welding gun 120 with gyro assembly 123. The gyro assembly 123 is attached to the rail 128 (not shown here) by means of the arrangement of wire 124 connected to the mechanical spring balancer 126 (shown in Figure 3). The spring balancer 126 is used for balancing the weight of spot welding gun 120.
Figure 7a shows the perspective view of upper bracket 132 mounted on the center column 112 of the modular single-column structures 100 and 110 shown in Figures 2 and 3. The upper end 130Aa of hinge pin 130A is pivoted therein.
Figure 7b shows the perspective view of lower bracket 134 mounted on the center column 112 of the modular single-column structures 100 and 110 shown in Figures 2 and 3. The lower end 130Ab of hinge pin 130A is pivoted therein. The horizontal member 130 is attached between these brackets 132, 134 with the help of hinge pin 130A, thrust bearing and ball bearing (not shown). The ball bearing is used to maintain separation between the bearing

races and to reduce rotational friction and to support radial and axial loads. Whereas, the thrust bearing is used for: (a) supporting the axial thrust; (b) preventing the shaft from drifting in the axial direction and transferring thrust loads applied on the shaft; and (c) vertically supporting the weight of the shaft and any components attached thereto. Further, the moving surface exerted against a thrust bearing is the area of the end of the shaft or the area of a collar attached at any point to the shaft.
Figure 8 shows the perspective view of one of the caster wheels 116 fitted at each corner of the base frame 114 of the modular single-column structures 100 or 110. The mounting plate 116A is fixed under the base frame 114 by means of suitable fasteners, e.g. nut-bolts or Allen screws. A U-bracket 116B is rotatably mounted under the mounting plate 116A for facilitating a 360° rotation or turning of the caster wheel for movement of the structure in any desired direction. Bearings (not shown) are mounted inside the wheels 116C. These caster wheels 116 are used to move the modular single-column structure from one location to the other. Normally, locking type of caster wheels are selected for the purpose of locking the modular single-column structure 100, 110 after finalising the location for spot welding process.
Figure 9a shows the perspective view of the cap plate 116D to cover ball bearings (not shown) fitted on upper and lower bracket 132 and 134 respectively of the modular single-column structures 100, 110 shown in the figures 2, 3. The cap plate 116D is used to cover ball bearing to fall from upper and lower brackets 132 and 134 respectively and to avoid ingress of dust particles inside the bearings.
Figure 9b shows the perspective view of an 'L' shaped anchor plate 121 for fastening the structure 100, 110 shown in figures 2, 3. The base frame 114 of the modular single-column structure 110 shown in Figure 3 is fastened to the ground with the help of anchor bolt (not shown). A vertical slot 121A is provided for adjusting the difference in levels between the ground and base frame 114. Hole 121B is used to fastening an anchor bolt of size M12 to ground.

Figure 9c shows the perspective view of one of the water tank 122 to be fitted on the base frame 114 of the modular single-column structures 100, 110 shown in Figures 2, 3. It has water filling opening 122A on top thereof and a water level glass 122B on one side thereof. It has two main functions: (a) to help in counter balancing the loads acting on the structure due to the overhanging assemblies of the horizontal member and spot welding gun by means of the weight of water contained therein; and (b) to store water required for cooling of the spot welding gun.
Figure 10 shows the perspective view of water pump 136 for supplying water for cooling the spot welding gun. The water pump is mounted on the base frame 114 of the modular single-column structure 100, 110. Water pump 136 is used to circulate water from water tank 122 to the arm of spot welding gun 120 to avoid overheating thereof and to achieve better welding spot quality.
Working of the Invention:
The modular structure in accordance with the invention is basically compact and rigid in construction. It is used for to conducting off-line trials of the spot welding fixture with spot welding guns. To conduct these off-line trials, a structure is required for suspending the spot welding gun and to move the gun along and transverse the car direction (X and Y axis respectively). The movement along X axis is achieved by transferring the gun 120 / mechanical spring balancer 126 in rail 128 thru the load trolley. The movement along Y axis, i.e. transverse to the car direction is achieved by rotational axis of the horizontal member 130. It rotates around the axis of hinge pin 130a. This hinge pin is fitted in upper bracket 132 with one ball bearing and in lower bracket 134 with one thrust bearing and one ball bearing. Once the gun is moved, it moves along and transverse to the car direction. The compass area of the movement is radially 3.7 meters, however the base area required for this structure occupying the floor space for its construction is just 2x2 meters. Up and down movements are achieved by mechanical spring balancer 126, which is useful for balancing the gun and also for achieving varying up/down heights. Since a spot weld gun 120 and horizontal beam

130 are constructed with cantilever type load (at 3.7 meters), the structure could have toppled, but this has eliminated with the help of the position of water tank 122 containing about 500 liters of water. This large water quantity acts as a counterweight to balance the structure weight equivalent to 500 kgs. Further, the positions of control panel 118 and water pump 136 are also kept in opposite direction with respect to the cantilever load, so these units also serve as counterweights. In addition to these safety features, L plates 121 are also provided to fix this structure 100 with ground by means of anchor bolts (not shown). While conducting spot welding gun fixture structure trial, the water pump 136 sucks water from water tank 122 and delivers the same to the spot welding gun via a flexible pipe. Once this water is discharged from the spot welding gun, this water is again collected in water tank 122 via flexible pipe and this cycle continues. This water flow is required to facilitate cooling of the spot welding gun 120, because it gets heated after spot welding operation. The control panel 118 controls and delivers the spot parameter as per the operational requirements and the targeted setting is done accordingly.
Because of its modular construction, the structure can be dismantled and stored within a smaller space as compared to the conventional 4-column structure shown in Figure 1. The operating range of this modular structure is about 3.7 meters radially. Therefore, it covers a larger area due to its compact size, which also substantially reduces its cost due to modular structure thereof. For the same reasons, time required for installation and dismantling is also very little, i.e. about 35~40% of the conventional 4-column structure. Moreover, more than 4 structure can be simultaneously tried due to availability of increased space in comparison to the conventional 4-column structures.
Technical advantages and economic significance
The modular single column structure for off-line spot welding gun trials on fixtures provided in accordance with the present invention has the following advantages:

Compact in size
• Safe
Operating range of 3.7 meters radially
Assembly & dismantling time is very less
No additional central water pipe line is required. (Inbuilt available)
• Low investment cost
Robust structure.
Low maintenance
Portable
Occupy less space to store after dismantling
Access to spotting in intricate & inaccessible area is possible which is
not possible with conventional type
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.
The use of the expression "a", "at least" or "at least one" shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.
The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention.
Although, only the preferred embodiments have been described herein, the skilled person in the art would readily recognize to apply these embodiments with any modification possible within the spirit and scope of the present invention as described in this specification. Therefore, innumerable changes, variations, modifications, alterations may be made and/or integrations in

terms of materials and method used may be devised to configure, manufacture and assemble various constituents, components, subassemblies and assemblies according to their size, shapes, orientations and interrelationships.
The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.
While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim:
1. A modular compact structure for conducting off-line trials of the spot
welding gun fixtures, the structure comprises:
- a base frame lockable on ground by means of anchor plates after on-site positioning of the structure;
- a plurality of caster wheel assembly;
- a single-column centrally disposed on the base frame;
- a water tank with flexible connection pipes for cooling spot welding gun arm;
- a horizontal member assembly fixed on the central column for suspending a spot welding gun;
- a spot welding gun suspension means with spring balancer arrangement;
- a horizontal member support arrangement with bearings; and
- a control panel for controlling the spot welding cycle and for balancing the modular single-column structure;
wherein the control panel, water tank and water pump are supported on the base frame in order to counterbalance the weight of the horizontal member assembly and spring balancer counterbalances the spot welding gun weight.
2. Modular compact structure as claimed in claim 1, wherein the horizontal member assembly comprises a horizontal member fixed at the top of the central column between a pair of upper and lower brackets fixed thereon.
3. Modular compact structure as claimed in claim 2, wherein the horizontal member comprises a hinge pin welded at one end thereof, one end each of said hinge pin adapted to rotatably pivot said horizontal member between said upper and lower brackets via ball and thrust bearings respectively.

4. Modular compact structure as claimed in claim 2, wherein the horizontal member further comprises a rail section having a slot in lower edge thereof for moving the spot welding gun in desired spot welding position by means of a suspended wire and spring balancer arrangement.
5. Modular compact structure as claimed in claim 4, wherein the spring balancer arrangement comprises a gyro assembly attached to said rail section by means of a wire arrangement.
6. Modular compact structure as claimed in claim 1, wherein each of said plurality of caster wheel assembly comprises:

- a mounting plate fixed under the base frame of the structure;
- a U-bracket rotatably mounted under said mounting plate for facilitating a 360° rotation of the caster wheel thereunder; and
- a caster wheel with bearings.

7. Modular compact structure as claimed in claim 2, wherein a respective cover plate is provided in said upper and lower brackets for retaining the bearings within said brackets and for protecting from ingress of harmful foreign particles into the bearings.
8. Modular compact structure as claimed in claim 1, wherein at least one anchor plate is provided for fastening the modular compact structure to the ground by means of a plurality of anchor plates and a vertical slot is provided for adjusting the level difference between the ground and the base frame of said modular compact structure.
9. Modular compact structure as claimed in claim 1, wherein the water tank and control panel are mounted on the base frame in order to counterbalance the horizontal member assembly and the spot welding gun suspending therefrom.

10. Modular compact structure as claimed in claim 1, wherein the control panel controls and delivers the spot welding parameters as per the operational requirements and the targeted settings.