Description:FIELD OF INVENTION

The present invention relates to replacing the tip of a spot-welding gun electrode-tips. In particular, the present invention relates to replacing the electrode-tips of spot-welding guns used in robotic cell/zone for spot-welding in a manufacturing plant. More particularly, the present invention relates to replacing the electrode-tips of spot-welding guns mounted on robotic arms used in the robotic cell/zone for spot-welding of the sheet-metal panel production-lines, e.g. Body-in-White (BIW) production-lines in an automobile manufacturing plant.

BACKGROUND OF THE INVENTION

Conventionally, the process of replacing the spot-welding robot gun electrode tip is done within the boundary of the spot-welding gun robot zones. However, it is very hazardous process because there is continuous human movement in such robot zones.

Normally, this electrode-tip replacement activity requires about 120 to 180 seconds for completion thereof, as per the spot-welding guns fitted on these robots. This process leads to stopping all other robotic functions in this zone reserved for spot-welding operations, when even a single electrode tip requires replacement as per the signal received from Human Machine Interface (HMI). This is a standard process followed in all automobile manufacturing plants during their Body-In-White (BIW) making process performed in such robotic spot welding zones.

In the applicant’s popular SUV manufacturing Bodyshop, there are multiple spot-welding robots for making the BIWs. In this process, the copper tips of the electrodes of the spot-welding guns mounted on robotic arms require replacement after completion of a predefined number of spot-welds.

During this activity, the maintenance/service personnel need to go inside these robotic zone by adopting all safety provision prescribed as per the established safety protocol therefor. However, this process takes-up considerable time, and until this tip-replacement in one or more spot-welding gun electrodes is completed, and thus the other serviceable robots in same robotic zone are interrupted from continuing their spot welding process.

Here, it is also necessary to understand the existing BIW making and benchmarking process. For example, the BIW manufacturing facilities use the traditional process of their service/maintenance personnel going inside the robotic zone for replacing the worn-out spot-welding electrode tips. The spot-welding electrode tip wears out, e.g., after every 4000 Spots and due to this tip-wear, the strength of the welded spot gets weakened. This results in the failure of the welding spot during Prybar test. This weakened spot-weld leads to an unsafe condition for the total strength of BIW from the point of view of the rigidity thereof.

Therefore, there is a need to replace the electrode-tips of the spot-welding guns mounted on the robotic arms used in the robotic cells by the service/maintenance personnel after going inside the robotic cell/zone fencing as per the standard protocol prescribed by the OEMs.

Therefore, the applicant tried to find out the best solution for replacing the worn-out tips of the spot-welding gun electrode-tips in such robotic zones in their BIW making units. Since the strength of the spot-welds on BIWs cannot be compromised, such worn-out tip-replacement cannot be eliminated.
As the hazard of the service/maintenance personnel going inside the spot-welding guns’ robotic zone for replacing the electrode-tips cannot be ruled out at all, it was brainstormed to use Henrich Triangle (Figure 1) for implementing the substitution by engineering controls.

Another option was to consider whether the robotic arms fitted with the spot-welding guns can be brought to the spot-welding robotic zone fencing for replacing the spot-welding gun electrode-tips instead of the conventional/existing process of the service/maintenance personnel entering inside such robotic zone in BIW making units.

It was decided to use the first option of Henrich Triangle while implementing an innovative solution proposed by the inventors and making a provision for moving the robotic arms mounted with the spot-welding guns to the robotic zone fencing for replacing the desired/worn-out copper tips of the spot-welding gun electrodes from outside this zone. This has eliminated the holding time necessary for interrupting the operation of other spot-welding gun robotic arms in the same robotic zone from performing their respective spot-welding operations.

DESCRIPTION OF THE INVENTION

In accordance with the present invention, a mechanism and process is provided for a safer and more efficient electrode-tip replacement of the spot-welding guns mounted on robotic-arms for welding on Body-In-White (BIW) production-line in an automobile production plant and the like. The process for replacing worn-out/consumed/defective electrode-tips is conducted on the robotic arms mounted with spot-welding guns on the spot-welding robots by staying outside robotic cells in the robotic zone.
The present invention concerns a process for “Single Minute Electrode Tip Replacement-SMETR” which does not require the operator to go inside the robotic cell for replacing the spot-welding gun electrode tips. This process leads to a substantial reduction in the process time as there is no need to stop the complete spot-welding robotic zone of the BIW production-line for replacing the defective or worn-out/consumed electrode tips. Therefore, the present invention leads to an improvement in the efficiency of the BIW production line and the like.

Here, the operator need not stop the entire robotic cell operation and the worn-out/consumed/defective electrode tips can be replaced by the operator even from standing outside the robotic cell, i.e., without entering inside the affected robotic cell and thus the operation of the other robots is not affected at all.

The above process involves incorporating the following controls therein:

1. Robot and the logic of the Programmable Logic Controller (PLC) is suitably modified by computer simulation to make it move near the robot-cell window/s without affecting other accessories for tip replacement.

2. The PLC also selects the most appropriate window on the walls/sides of the robotic cell, which is within the accessible span of affected robot.

3. Interlocking is done with AND gate logic for all conditions OK, only then the affected robot’s movement is allowed.

3. Safety gate plug is configured as a positive Man-Machine control.

4. Lamp is fixed for indicating the continuation of tip-replacement process.

5. Work Complete (acknowledgement) switch is provided near the electrode tip-replacement window outside the robotic cell.
6. Safety mat switch is provided for the safety of the personnel performing the robot tip replacement.

The following are the advantages of the New Tip Replacement Process:

1. Injury during the electrode tips replacement process is eliminated, which results in substantial productivity enhancement, because the operator is conducting this process from outside the robotic cell.

2. The time required for replacing the tip is brought down from 2.5 minutes to just 1 minute, which also results in improving the process productivity.

3. The operator’s moral is improved due to substantial reduction in the time for replacing the tip and thereby unnecessary non-value addition efforts are eliminated and his/her safety is also improved substantially.

4. This also avoids the operator from the hazards of slippage, falling and collision within the robotic cell, as going inside the robot cell for tip-replacement is not required at all.

5. This invention offers a Low-cost solution over the existing automatic robot-tip changing Unit, each costing INR 3.90 Lacs, resulting in a potential cost saving of Rs.253 Lacs for 65 robots at applicant’s single production line.

The inventive process of robot-tip replacement discussed above is identified for a Horizontal Deployment in a series of robots, e.g. MB60 R05, MB50 R02, MB50 R03, MB20 R03, UB60 R1, UB60 R02, UB30 R01, UB30 R02, UB30 R03 , UB30 R04 (10 Robot types identified).
Robot Location No. of Robot Welding Guns Time saved for robot-tip replacement Hold-time saved by avoiding the stopping of other robot-operations. Total time saved.
Plant 1 65 130 2.10 Hour 4.20 Hr
Plant 2 190 380 min. 6.33 Hour 13 Hr
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 process for replacing electrode-tips of spot-welding guns by staying outside the robotic zone for spot-welding of Body-In-White in an automobile manufacturing plant.

Another object of the present invention is to provide a process for replacing electrode-tips of spot-welding guns to reduce the tip-replacement time.

Still another object of the present invention is to provide a process for replacing electrode-tips of spot-welding guns to avoid injury to operators.

Yet another object of the present invention is to provide a process for replacing electrode-tips of spot-welding guns to ensure the safety of operators.

A further object of the present invention is to provide a process for replacing electrode-tips of spot-welding guns to enhance the operator’s morale.

A still another object of the present invention is to provide a process for replacing electrode-tips of spot-welding guns to reduce the cost of spot-welding process.

A still another object of the present invention is to provide a process for replacing electrode-tips of spot-welding guns to increase the operational efficiency of the robotic spot-welding process.

A yet further object of the present invention is to provide a process for replacing electrode-tips of spot-welding guns, which can be deployed across all industries, particularly in automobile and mechanical industry.

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 INVENTION

In accordance with the present invention, there is provided a mechanism for replacing spot-welding gun electrode-tips on robotic-arms for spot-welding robots on sheet-metal panel production-lines, the mechanism comprises:

• a robotic cell equipped with a plurality of the spot-welding robots for making spot-welds on sheet-metal panels, the robotic cell having a plurality of windows at predefined locations on the walls/sides thereof, to be accessible by the operator for replacement of spot-welding gun electrode-tips;

• each of the spot-welding robots fitted with a spot-welding gun mounted on the robotic arm thereof, the robots moveable within a predefined range inside the robotic cell to extend the robotic arms thereof to cover a predefined portion of the robotic cell;

• the spot-welding gun fitted with electrode-tips for making spot-welds on the sheet-metal panels; and

• each electrode-tip capable of making a predefined number of spot-welds on the sheet-metal panels;
wherein a programmable logic controller (PLC) along with a Human-Machine-Interface (HMI) display is placed on a control panel located outside the robotic cell, the PLC is configured to store a predefined number of spot-welds for spot-welding gun electrode-tips, to count the number of spot-welds made by the spot-welding gun electrode-tips, to indicate the corresponding robot in which the electrode-tips thereof have exceeded the predefined number of spot-welds.

Typically, the programmable logic controller (PLC) counts the spot-welds made by each spot-welding gun; and on exceeding the predefined number of spot-welds by any of the spot-welding robots, directs the robot depending on the accessibility thereof, to move to one of the windows located at an optimal distance therefrom for the operator standing close to the window to carry-out the electrode-tips replacement thereof.

Typically, the window alternatively accommodates one of the spot-welding robots for electrode-tips replacement thereof.

Typically, each of the windows is fitted with a respective gate plug for disabling the operation of the predefined spot-welding robots depending on the accessibility thereof to the window for carrying out the electrode-tips replacement.

Typically, each of the spot-welding robots is configured to move to the window only after completion of the interlocking thereof with AND gate logic for all conditions OK therefor.

Typically, an indication lamp is fitted in the vicinity of each of the windows to glow until the electrode-tips replacement is continuing at the respective window; and wherein an acknowledgement button switch is fitted near each of the windows, to be pressed after the completion of the electrode-tips replacement at the respective window.

In accordance with the present invention, there is also provided a process for replacing the electrode-tips of the spot-welding gun on robotic-arms for the spot-welding robots by the aforesaid mechanism, the process comprises:

- predefining the number of spot-welds to be made by the spot-welding gun electrode-tips, in the controller of a robotic-cell;

- counting number of spot-welds to be made by the electrode-tips of each spot-welding robotic arm by the controller, and indicating on Human Machine Interface (HMI) display and Annunciator system, the identity of the corresponding spot-welding robotic arm which has exceeded the predefined number of spot-welds and requires the electrode-tips replacement thereof;

- assessing the accessibility of the robot spot-welding requiring electrode-tips replacement to one of the windows located at a predetermined distance therefrom and directing the robot to the window for electrode-tips replacement thereof;

- switching-off the water valves from Filter and Regulator (FR) unit by the operator on the spot-welding robot reaching the window;

- removal of the respective gate plug of the spot-welding robot at the window by the operator after standing on the safety mat of the window;

- opening of the window by the operator and replacing the electrode tips of the spot-welding robotic arm of the robot;

- closing of the window and re-fixing of the gate plug;
- switching-on the water valves from FR unit by the operator and moving away from the safety mat,

- pressing by the operator of the electrode tip change complete (acknowledge) button placed in the vicinity of the window; and

- starting of the program dedicated for dressing of the replaced electrode-tips by the spot-welding robot and resuming the ‘Home’ position thereof.

Typically, the process comprises moving of the spot-welding robot to the window only after completion of the interlocking thereof with AND gate logic for all conditions OK therefor.

Typically, the process comprises continuous glowing of an indication lamp fitted in the vicinity of the window until the electrode-tips replacement is in progress at the window.

Typically, the process comprises pressing by the operator of the acknowledgement button switch fitted near the window, after the completion of the electrode-tips replacement at the window.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described in the following with reference to the accompanying drawings.

Figure 1 shows Henrich Triangle for Hierarchy of Controls.

Figure 2 shows the flow-chart of the conventional set-up of the method for the electrode tips replacement by the operator after going inside the robotic zone and the important limiting features thereof.
Figure 3 shows the flow-chart of the improved set-up configured in accordance with the present invention for the electrode tips replacement on the robotic arm by the operator from outside the fence of the robotic zone, as shown in Figure 2.

Figure 4 shows an actual perspective view of the set-up configured in accordance with the present invention as shown in Figure 3.

Figure 5 shows the main features of the electrode tip-changing mechanism for changing/replacing the electrode-tips of spot-welding guns on robotic arms during production of Body-In-White (BIW) in automobile manufacturing plant and the like.

Figure 6 shows a safer and more efficient mechanism configured in accordance with the present invention for electrode-tip replacement facilitated from outside the fence of the robotic zone, as shown in Figure 2. This window is provided in one of the walls/sides of the robotic cell used for a plurality of spot-welding guns mounted on robotic arms.

Figure 7 shows an enlarged view of the window shown in Figure 6 for electrode-tip replacement facilitated from outside the robotic zone.

Figure 8 shows a process flow in the conventional set-up for the electrode tip-changing method shown in Figure 2 for the electrode-tips replacement by the operator after going inside the robotic zone.

Figure 9 shows process flow in the improved set-up for the electrode tip-changing method shown in Figure 3 for the electrode-tips replacement by the operator facilitated from outside the robotic zone.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the process for replacing electrode-tip of spot-welding gun configured in accordance with the present invention and by staying outside robotic zone for spot-welding of Body-In-White in an automobile manufacturing plant, will be described in more detail with reference to the accompanying drawings without limiting the scope and ambit of the present invention.

Figure 1 shows Henrich Triangle or an accident triangle, which is based on a theory for preventing accidents in industries. It shows a relationship between serious accidents, minor accidents and near misses. This theory propounds that when there is a reduction in the number of minor accidents, there will also be a corresponding fall in the number of serious accidents. Henrich Triangle shows the Hierarchy of Controls for improving the safety on shopfloors in different industries. It is visible here that the safety of the workers improves from the bottom tip of this inverted triangle to the base at the top thereof. So, the measure taken on top are most-effective accident prevention tools and by going towards the bottom tip thereof, the effectiveness of accident prevention gradually deteriorates. According to this triangle, there are 5 steps, viz.
(i) Elimination by removing the physical hazards on/around the shopfloor,

(ii) Substitution concerns replacing the objects posing hazards,

(iii) Engineering controls to isolate people from the hazards on/around the shopfloor,

(iv) Administrative controls, i.e., changing the way people work in/around the shopfloor, and

(v) PPE means protecting the people by encouraging them to use the Personal Protective Equipment (PPE).
Figure 2 shows the flow-chart of the conventional set-up for the electrode tip-changing method. The conventional method is as follows:

(a) At step 10, there is an indication on Human Machine Interface (HMI) and Annunciator system for changing these worn-out/consumed electrode-tip/s, when the electrode-tip/s mounted on the robot arm of the spot-welding robot working in an automobile Body-In-White (BIW) producing robotic zone is worn-out/consumed after spot-welding operation is continuing for a certain duration,

(b) At step 20, the operator reaches the control panel and puts the robotic cell from automatic mode into manual mode and then approaches the safety gate of the robotic cell in the robotic zone equipped with a plurality of spot-welding robot working in BIW production line in an automotive manufacturing plant or the like,

(c) At step 30, the operator removes the gate plug and puts it in pocket for own safety,

(d) At step 40, the operator reaches close to servo-gun inside the robotic cell and switches-off the water-IN and water-OUT valves,

(e) At step 50, the operator replaces the worn-out/consumed spot-welding electrode tips and switches-on the water-IN and water-OUT valves,

(f) At step 60, the operator exits the robotic cell after above electrode tip-changing activity and puts on the gate plug again,

(g) At step 70, the operator goes to control panel again and puts the robotic cell in the automatic mode,

(h) At step 80, the operator confirms that the electrode-tip is changed by pressing the acknowledge button provided on HMI display, and finally,

(i) At step 90, the spot-welding gun robot starts the program dedicated for dressing the new electrode-tips and resumes the ‘Home’ position thereof.

However, the disadvantage with the conventional set-up for replacing the electrode tip/s mounted on robotic arms of the spot-welding guns used within robotic cells inside a robotic zone as discussed above is that the operator has to first stop the automatic mode of the robotic cells and put it on a manual mode, and then remove the gate plug and enter inside the robotic cell to the indicated spot-welding robot for changing the worn-out/consumed/defective electrode-tip/s only after the water in-out valves are closed. This is a time-consuming and inefficient process, which not only disables the defective spot-welding robot but also disables all other such robots even with working electrode tips.

Figure 3 shows the flow-chart of the process configured in accordance with the present invention to replace electrode-tips from outside robotic zone fence:

(j) At step 110, there is an indication on Human Machine Interface (HMI) and Annunciator system for changing these worn-out/consumed electrode-tip/s, when the electrode-tip/s mounted on the robot arm of the spot-welding robot working in an automobile Body-In-White (BIW) producing robotic zone is worn-out/consumed after spot-welding operation has continued for a certain duration,

(k) At step 120, the operator reaches the electrode tip changing window and switches-off the water valve from filter and regulator (FR) unit,

(l) At step 130, the operator stands on the safety mat switch and removes the gate plug of the electrode tip change window,

(m) At step 140, the operator opens the window and changes both the electrode tips (both robotic arms have an electrode-tip for a spot welding gun on each robot),

(n) At step 150, the operator switches-off the electrode-tip change window and fixes the gate plug,

(o) At step 160, the operator switches-on the water valve from FR unit and moves away from the safety match switch,

(p) At step 170, the operator presses the electrode tip change complete (acknowledge) button placed near the electrode tip change window, and

(q) Finally at step 180, the spot-welding gun robot starts the program dedicated for dressing the new electrode-tip and resumes its ‘Home’ position.

The disadvantages of the conventional set-up requiring the operator to move inside the robotic zone containing a plurality robots with robotic arms mounted with multiple spot-welding guns only after stopping the automatic mode of all the robots working inside are avoided by the process configured in accordance with the present invention.

This way only the robot requiring the electrode tips replacement is stopped by removal of its gate plug by the operator right from the corresponding window and rest of the robot may continue their operations.

The process sequence is suitably modified to enable the robot/s with worn-our/consumed/defective electrode tips to move toward a window allotted to is based on its optimum distance from the windows provided on the walls/sides of the robotic zone. This facilitates in keeping the other robots in operational mode and thus the complete operation of the robotic welding zone is not required to be stopped. For this purpose, there is a provision for a plurality of windows, each equipped with a control and display panel adjacent thereto. Therefore, the electrode-tips replacement process of the present invention is rendered substantially efficient process which disables only defective spot-welding robot/s and allows all other robots to continue their operations.

Figure 4 shows a perspective view of the set-up configured in accordance with the present invention for Robot tip Replacement from outside the fence of the Robotic zone.

Figure 5 shows the main features of the mechanism for changing/replacing the electrode-tips of spot-welding guns mounted on the robotic arms used for producing of the Body-In-White (BIW) in automobile manufacturing plant and the like. It shows a button B1 for acknowledging the completion of the electrode-tips replacement, a plurality of robot pneumatic air-pressure supply unit with filter and regulator FR units, and a safety mat switch S1, and an indication lamp L1 for displaying the continuation of electrode-tip-replacement process.

Figure 6 shows a schematic representation of the mechanism for changing/replacing the electrode-tips of spot-welding guns for producing BIWs shown in Figure 5. This mechanism configured in accordance with the present invention enables the operator to replace the electrode-tips right from outside the robotic zone fence, as shown in Figure 4. A window W is provided with a gate plug GP fitted in one of the walls/sides of the robotic cell RC used for a plurality of spot-welding guns mounted on robotic arms. This robotic zone is surrounded by a protective shield PS and fitted with a button B1 to be pressed to acknowledge the completion of the electrode-tips replacement, so as to enable the spot-welding gun robot in which the electrode tips are replaced, for starting the program dedicated for dressing the new electrode-tips and thereafter to resume its ‘Home’ position inside the robotic zone. An indication lamp L1 is installed at a suitable height near the window W to display the continuation of the electrode-tip-replacement process when it is in progress. A safety mat switch S1 is also provided for the operator to stand thereon for removing the gate plug GP of the electrode tip change window W. With this mechanism, the operator does not require to go inside the robotic zone/cell to replace the electrode tips, and can very well do this operation by standing facing this window W from outside robotic cell RC. This avoids the stoppage of all robotic arms along with one having defective/worn-out/consumed electrode tips and thus saves down-time to enhance the productivity. This also makes the process of electrode-tips replacement on the robotic arms of spot-welding guns located inside a robotic zone/cell completely hazard-free, saves down-time of all other robotic arms of spot-welding guns located inside that particular robotic cell RC and makes it more cost-effective. Although, the present invention is discussed with reference to BIW spot-welding process in automobile production lines, it is obvious that the basic concept and idea underlying the present invention can be easily implemented across all sheet metal welding processes/equipment using spot-welding guns mounted with robotic arms carrying electrode tips which wear out/get consumed during spot-welding process on any type of sheet metal products. It shows the wall/side of the robotic cell RC on which the mechanism configured in accordance with the present invention is fixed for conducting the electrode-tip replacement process right from outside the robotic cell RC, as shown in Figure 3. This window W is fitted with a gate plug GP.

Figure 7 shows an enlarged view of the window shown in Figure 7 for electrode-tip replacement facilitated from outside the robotic zone. It shows the gate plug GP fitted on the window W provided on one of the sides/walls of the protective shield enclosing and forming a robotic cell RC.

Figure 8 shows a process flow in the conventional set-up for the electrode tip-changing method shown in Figure 2 for the electrode-tips replacement by the operator after going inside the Robotic zone, which process is as follows:

S Electrode-tips replacement process starts.
C1 Controller identifies and stops robot/s requiring electrode tips change.
C2 Controller indicates defective robot on HMI and Annunciator system.
C3 Controller stops the defective robot immediately.
C4 Operator switches off the pneumatic supply to robotic cell.
C5 Operator reaches control panel to put robotic cell in manual mode.
C6 Operator reaches the safety gate of the robotic cell.
C7 Operator removes gate plug and safely keeps it.
C8 Operator reaches servo-gun in robotic cell to close water supply valves.
C9 Operator replaces electrode tips & reconnects water supply valves.
C10 Operator replaces electrode tips & reconnects water supply valves.
C11 Operator exits robotic cell and refixes gate plug.
C12 Operator reaches the control panel to put the robotic cell in auto mode.
C13 Operator presses the tip/s change acknowledge button 'on HMI display.
C14 Robot starts robot tip dressing operation & reaches its ‘Home’ position.
E Electrode-tips replacement process ends.

Figure 9 shows process flow in the improved set-up for the electrode tip-changing method shown in Figure 3 for the electrode-tips replacement by the operator facilitated from outside the robotic zone.
S Electrode-tips replacement process starts.
P1 Controller raises an alarm on HMI and Annunciator system.
P2 Controller stops only the defective robot/s immediately.
P3 Controller switches off the pneumatic supply to defective robot.
P4 Controller selects nearest window/s for robot/s to move for tip change.
P5 Controller directs the defective robot/s to the selected window/s.
P6 Defective robot/s reach/es the said window.
P7 Operator reaches said window to close water supply valves from (FR) Unit.
P8 Operator stands on safety mat to remove the gate plug of said window.
P9 Operator opens said window to change both electrode tips.
P10 Operator closes said window and refixes gate plug of said window.
P11 Operator reconnects the water supply valves from FR Unit.
P12 Operator comes off from the safety mat.
P13 Operator presses “tips changed” acknowledge button close to window.
P14 Robot starts robot tip dressing operation & reaches its home position.
P15 Electrode-tips replacement process according to the invention ends.
E Electrode-tips replacement process ends.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The mechanism and process configured in accordance with the present invention for a safer and more efficient electrode-tip replacement of the spot-welding gun mounted on robotic-arms for welding on Body-In-White (BIW) production line in an automobile production plant and the like, offers the following advantages:
• Introduces the process of replacing the robotic spot welding gun electrode tip on BIW production line for the safety of the operator in automobile Industry.

• Reduction in electrode tip replacement time by 70%.

• Eliminates the mandatory stoppage of the functioning of other robots in the same robot cell by electrode tip-replacement from outside of robot-cell.

• Increases the BIW production line efficiency by 10%.

• Eliminates the hazard of man-movement within robotic-cell for electrode tip-replacement.

• Simplifies the process of electrode tip-replacement.

• Offers the scope for widespread deployment across the applicant’s other manufacturing plants/facilities using Robotic Spot-Welding Guns.

• Eliminates the need for going inside the robot-cell as in the conventional electrode tip replacement process.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.

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. 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, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to imply 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 to achieve one or more of the intended objects or results of the present invention.

The description of the exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top”, and “bottom” as well as derivatives thereof (e.g., “horizontally”, “inwardly”, “outwardly”; “downwardly”, “upwardly” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion.

These relative terms are for convenience of description and do not require that the corresponding apparatus or device be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected”, refer to a relationship, wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. , Claims:We claim:

1. A mechanism for replacing spot-welding gun electrode-tips on spot-welding robots for sheet-metal panels on production-lines, said mechanism comprises:

• a robotic cell (RC) equipped with a plurality of said spot-welding robots for making spotwelds on sheet-metal panels, said robotic cell (RC) having a plurality of windows (W) at predefined locations on the walls/sides thereof to be accessible by the operator for replacement of spotwelding gun electrode-tips;

• each of said spot-welding robots fitted with a spot-welding gun mounted on the robotic arm thereof, said robots moveable within a predefined range inside said robotic cell (RC) to extend the robotic arms thereof to cover a predefined portion of said robotic cell (RC);

• said spotwelding gun fitted with electrode-tips for making spot-welds on said sheet-metal panels; and

• each electrode-tip capable of making a predefined number of spot-welds on said sheet-metal panels;

wherein a programmable logic controller (PLC) along with a Human-Machine-Interface (HMI) display is placed on a control panel located outside said robotic cell, said PLC is configured to store a predefined number of spotwelds for spot-welding gun electrode-tips, to count the number of spot-welds made by said spot-welding gun electrode-tips, to indicate the corresponding spot-welding robot in which the electrode-tips thereof have exceeded said predefined number of spot-welds.

2. The mechanism as claimed in claim 1, wherein said programmable logic controller (PLC) counts the spotwelds made by each spot-welding gun; and on exceeding said predefined number of spot-welds by any of said spot-welding robots, directs said robot depending on the accessibility thereof, to move to one of said windows located at an optimal distance therefrom for the operator standing close to said window to carry-out the electrode-tips replacement thereof.

3. The mechanism as claimed in claim 1, wherein said window (W) alternatively accommodates one of said spot-welding robots for electrode-tips replacement thereof.

4. The mechanism as claimed in claim 1, wherein each of said windows (W) is fitted with a respective gate plug (GP) for disabling the operation of said predefined spot-welding robot depending on the accessibility thereof to said window (W) for carrying out the electrode-tips replacement.

5. The mechanism as claimed in claim 2, wherein each of said spot-welding robots is configured to move to said window (W) only after completion of the interlocking thereof with AND gate logic for all conditions OK therefor.

6. The mechanism as claimed in claim 1, wherein an indication lamp (L1) is fitted in the vicinity of each of said windows (W) to glow until the electrode-tips replacement is continuing at said respective window (W); and wherein an acknowledgement button switch (B1) is fitted near each of said windows (W) to be pressed after the completion of the electrode-tips replacement at said respective window (W).
7. A process for replacing the electrode-tips of the spot-welding gun on robotic-arms for the spot-welding robots by the mechanism as claimed in preceding claims, said process comprises:

- predefining the number of spot-welds to be made by the spot-welding gun electrode-tips, in a controller (PLC) of a robotic-cell (RC);

- counting the number of spot-welds to be made by the electrode-tips of each spot-welding robotic arm by said controller (PLC), and indicating it on Human Machine Interface (HMI) display and annunciator system, identifying the corresponding spot-welding robotic arm which has exceeded said predefined number of spot-welds and requires the electrode-tips replacement thereof;

- assessing the accessibility of said spot-welding robot requiring electrode-tips replacement to one of said windows (W) located at a predetermined distance therefrom and directing the corresponding robot to said window (W) for electrode-tips replacement thereof;

- switching-off the water valves from Filter and Regulator (FR) unit by the operator on said spot-welding robot reaching said window (W);

- removal of the respective gate plug (GP) of said spot-welding robot at said window (W) by the operator after standing on the safety mat (S1) of said window;

- opening of said window (W) by the operator and replacing the electrode tips of the spot-welding robotic arm of said robot;

- closing of said window (W) and re-fixing of said gate plug (GP);

- switching-on the water valves from Filter and Regulator (FR) unit by the operator and moving away from said safety mat (S1);

- pressing by the operator of said electrode tip change complete (acknowledge) button (B1) placed in the vicinity of said window; and

- starting of the program dedicated for dressing of said replaced electrode-tips by said spot-welding robot and resuming the ‘Home’ position thereof.

8. The process as claimed in claim 7, wherein said process comprises moving of said spot-welding robot to said window (W) only after completion of the interlocking thereof with AND gate logic for all conditions OK therefor.

9. The process as claimed in claim 7, wherein process comprises the step of continuous glowing of an indication lamp (L1) fitted in the vicinity of said window (W) until the electrode-tips replacement is in progress at said window (W).

10. The process as claimed in claim 7, wherein process comprises the step of pressing by the operator, of the acknowledgement button switch (B1) fitted near said window (W) after the completion of the electrode-tips replacement at said window (W).

Dated this 12th day of March 2024.

Digitally / e-Signed by:

(SANJAY KESHARWANI)
APPLICANT’S PATENT AGENT
REGN. NO. IN/PA-2043.