DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See sections 10 & rule 13)
1. TITLE OF THE INVENTION
A MODULAR SERIES SPOT WELD JIG TO ACCOMMODATE DIFFERENT ANGULAR SIDEWALLS MANUFACTURING OF A RAIL
2. APPLICANT (S)
NAME NATIONALITY ADDRESS
BEML LIMITED IN BEML Soudha, No 23/1, 4th Main S.R. Nagar, Bengaluru- 560027, Karnataka, India.
3. PREAMBLE TO THE DESCRIPTION
COMPLETE SPECIFICATION

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION:
[001] The present invention relates to the field of spot welding jigs. The present invention in particular relates to a modular series spot weld jig to accommodate sidewall manufacturing of different rail coach variants.
DESCRIPTION OF THE RELATED ART:
[002] Manufacturing process of stainless-steel sidewall assembly of the metro rail coach involves resistance spot welding of various sheet metal parts with thin (2mm approx..) sidewall panel having window cut-outs. Sidewall assembly produced will have lot of distortions due to the heat induced while spot welding (500 spots approx. for every 4 meters) and since the Sidewall panel is very thin (2mm approx.) and having cut-outs in between at many places for windows. But, flatness accuracy of sidewall panel after welding should be within 1mm as per design requirement, since Sidewall panel comes in the exterior part of the rail coach and its aesthetics is very vital. Hence, to fabricate the stainless steel sidewall assembly without distortion and maintaining flatness of the Sidewall panel within 1mm in time is very critical and challenging.
[003] To deliver the Sidewall assembly in time and maintain flatness accuracy within 1mm, series spot welding process is used. This series spot weld process is done using a jig with copper base. This jig has a machined bed made of copper alloy material that acts as an electrode as well provides adequate support throughout the process while spot welding of sheet to the frame elements resulting in minimal distortion and achieving flatness accuracy within 1mm. This series spot weld jig is very expensive as jig top plate (backup electrode) is made of copper alloy.
[004] The geometry and dimensions of Sidewall assembly will differ for each new rail or metro coach variant. If there is no angular dimension variation in the new variant, the same series spot weld jig may be used for both the variants. But, whenever there is a change in angular dimension, a new weld jig is required for each new variant since the copper bed angle of the jig is fixed for one coach variant. However, any new procurement of series spot weld jig involves huge investment which indirectly increases the rail coach price.
[005] Prior to the development of this invention, the sidewall assemblies are manufactured in a fixed copper bed angle series spot weld jig which involves huge investment. If there are any design changes in the Sidewall angle of the coach, a new series spot weld jig with approximately same huge cost is required for that angle change.
[006] In order to overcome above listed prior art, the present invention aims to design and develop a modular type of series spot weld jig to accommodate different sidewall variants manufacturing of a rail coach in the same jig which is cost effective. The present jig eliminates the procurement of new jigs for each angle. The present invention comprises of development of a flexible series spot weld jig making the jig suitable to manufacture rail coach models having varied angular sidewalls in the same jig without disturbance of electric current continuity which is vital in series spot welding process. This development has been made using hinge and slider indexing mechanism wherein bottom half of the jig is fixed and the upper half rotatable around the mold point line axis thereby setting to the desired angle.
[007] Reference may be made to the following:
[008] Publication No. CN208628756 relates to a spot -weld machine's welding jig, including the spot -weld machine main part, the die -pin, bottom plate and workstation, spot -weld machine main part front end upper portion is equipped with a set of soldered connection, spot -weld machine main part front end middle part is equipped with a rhizophore pole, the soldered connection that the die -pin front end was equipped with a set of soldered connection and upper portion corresponds, die -pin lower extreme and both sides are equipped with the supporting shoe, die -pin and supporting shoe upper end fixed connection workstation, the workstation upper end is equipped with the slide rail, the slide rail upper end is through the two sets of relative sliders of spout sliding connection, slider one side fixed connection vaulting pole, vaulting pole fixed connection electric putter, electric putter fixed connection is on the side of workstation, be equipped with double -layered groove between two sets of sliders, the slider upper end is equipped with the grip block, the grip block is equipped with relative two, be equipped with double -layered groove between two grip blocks, the utility model discloses the clamp is tightly effectual, and stability is good, can dock two sets of welded work pieces that need automatically, appears when preventing manual butt joint misplacing.
[009] Contrary to the above Publication No. CN208628756 which refers to normal single spot butt welding, in the present invention, the process for which the weld jig is developed refers to series direct spot welding.
[010] Publication No. KR200450211 relates to a structure of a resistance spot welding facility for a rolling stock, and in particular, a resistance spot welding facility for a rolling stock equipped with a sliding footrest so as to adjust the gap between the welding facility and the body according to the overall width of the body to be assembled. The task is to provide structure. In order to solve the above problems, the present invention is a railway vehicle resistance spot welding facility structure having a spot welder mounting portion movable in the longitudinal direction of a vehicle body to be assembled along a rail at a predetermined height from the ground, so as to interlock with the spot welder mounting portion, once Provided is a railcar resistance spot welding equipment structure characterized by comprising a slide footrest fixed to the spot welder mounting portion, the other end of which can be slid in the width direction of the car body to adjust a gap with the car body. Railroad vehicle contrasting, resistance spot welding, slide scaffolding.
[011] Contrary to the above Publication No. KR200450211, which refers to a car body spot welding equipment structure, in the present invention, the weld jig is developed for different variants of sidewall as well for series spot welding process wherein electric current continuity is vital.
[012] Patent No. US6008471 relates to a welding station for motor-vehicle bodies or subassemblies thereof in which the body side panels are engaged during welding by locking devices arranged in the space between the body sides and carried by two locating gates which are rigidly connected to each other by means of quick coupling means.
[013] Contrary to the above Publication No. US6008471, which refers to a fixed welding station of a motor vehicle or its sub assemblies, the present invention refers to a flexible railway coach sidewall welding jig.
[014] Publication No. CN207824161 relates to a spot welding machine, inductor movable plate install in the slide rail cover, slide rail cover bottom installation slide rail panel, and slide rail gasket -mounted in slide rail panel inboard bottom, the baffle is installed in the panel side, side -mounting seamless steel pipe and pressure welding board in the panel front side installation side metal plate gold plate, panel, knife edge plate installs in the pressure welding prelaminar part, the horizontal installation of slide rail bottom plate one end moves movable support, and the pressure welding board is close to the tip installation stationary side plate who moves movable support, stationary side plate outside erection bracing curb plate and dodge gate, and backup pad and activity door reveal side's erection bracing frame, install in filling up foot iron and square tube the support frame bottom. The utility model discloses a move movable support drive inductor movable plate and remove so that the inductive switch who installs on the inductor movable plate is linear motion, when sensing weld workpiece, trigger the electrode action on the pressure welding board, accomplish spot welding to level and smooth to the welding position cutting by knife edge plate, degree of automation is high, and welding quality is stable.
[015] Contrary to the above Publication No. CN207824161, which refers to spot welding machine, the present invention refers to a weld jig.
[016] IN Publication No. 202141026818 relates to a set of multilayered (super-lattice) metamaterials, where on the top of silicon substrate, periodically thin films have been deposited along the z-direction resulting in patterned multilayer of aluminum (Al, non-magnetic) and nickel (Ni, magnetic). The proposed device consists of periodic array of unit cell designs (not isolated/ single particle) where metamaterial resonator is realized through superlattice arrangement of non-magnetic (Al) and magnetic (Ni) metals. This device combines the concept of giant-magneto resistance (GMR) and array of sub-wavelength structures (metamaterials) to be employed in both spintronics and terahertz photonics applications.
[017] Contrary to the above IN Publication No. 202141026818, which refers to invention related to materials, the present invention refers to development of a weld jig.
[018] IN Publication No. 2412/MUM/2012 relates to a method for producing side wall for railway passenger coach. The method 100 having steps of selecting a sheet with predefined grade, wherein the sheet is in coiled form. Thereafter, uncoiling the sheet for straightening. Further, lifting the sheet and disposing over a first pallet in alignment with a laser cutting machine. Then cutting openings and blanks of predefined shape on the sheet and placing the sheet in a second pallet. At last, securing the reinforcement frames and panels to the sheet to form side wall of the railway coaches.
[019] Contrary to the above IN Publication No. 2412/MUM/2012, which refers to invention related to manufacturing method of a specific sidewall, the present invention refers to development of a flexible weld jig for different railway coach variants.
[020] Publication No. US5287814 relates to a car body of railway rolling stock suitable for use for passenger cars or electric passenger cars and easy to fabricate at a low material cost. An underframe constituting the car body comprises a center underframe produced at light-alloy extruded shapes and an end underframe produced of a ferrous material, and a roof framing, a side framing and an end framing which constitute the car body are composed of outer plate members produced of a ferrous material and frame members produced of a ferrous material.
[021] Contrary to the above Publication No. US5287814, which refers to manufacturing method of the whole car body, the present invention refers to development of a flexible weld jig for different railway coach variants.
[022] Publication No. CN210359778 relates to a resistance manipulator spot welding portal frame for rail transit. The device comprises a platform, stand columns are fixedly connected to the left side and the right side of the lower surface of the platform, fences are fixedly connected to the periphery of the upper surface of the platform, U-shaped plates are arranged on the inner sides of the two stand columns and fixedly connected with the platform, a crawling ladder is fixedly connected to the right sides of the stand columns from the right, the crawling ladder is fixedly connected with the platform, and transverse plates are arranged on the inner sides. The utility model discloses a resistance manipulator spot welding portal frame for rail transit. The platform, the stand column, the U-shaped plate, the transverse plate, the connecting piece, the adjusting device, the welding module assembly and the mechanical arm are matched. By controlling rotation of the motor, the relative distance between the two manipulators can be adjusted, the manipulators can weld vehicle end walls of different thicknesses, the application range is widened, welding operation can be conducted on the two faces of each vehicle end wall at the same time, and the welding efficiency of the vehicle end walls is improved.
[023] Contrary to the above Publication No. CN210359778, which refers to a resistance manipulator spot welding portal frame, in the present invention weld jig is developed for different variants of sidewall as well for series spot welding process wherein electric current continuity is vital.
[024] Publication No. CN210306215 relates to a resistance manipulator spot welding portal frame for rail transit. The device comprises a platform, stand columns are fixedly connected to the left side and the right side of the lower surface of the platform, fences are fixedly connected to the periphery of the upper surface of the platform, U-shaped plates are arranged on the inner sides of the two stand columns and fixedly connected with the platform, a crawling ladder is fixedly connected to the right sides of the stand columns from the right, the crawling ladder is fixedly connected with the platform, and transverse plates are arranged on the inner sides. The utility model discloses a resistance manipulator spot welding portal frame for rail transit. The platform, the stand column, the U-shaped plate, the transverse plate, the connecting piece, the adjusting device, the welding module assembly and the mechanical arm are matched. By controlling rotation of the motor, the relative distance between the two manipulators can be adjusted, the manipulators can weld vehicle end walls of different thicknesses, the application range is widened, welding operation can be conducted on the two faces of each vehicle end wall at the same time, and the welding efficiency of the vehicle end walls is improved.
[025] Contrary to the above Publication No. CN210306215, which refers to a resistance manipulator spot welding portal frame, in the present invention weld jig is developed for different variants of sidewall as well for series spot welding process wherein electric current continuity is vital.
OBJECTIVES OF THE INVENTION:
[026] The principal objective of the present invention is to develop a modular series spot weld jig to accommodate all coach variants sidewall assemblies having different angles in a single type of jig.
[027] Another objective of the present invention is to fabricate a cost effective series spot weld jig for different rail coach sidewall assemblies manufacturing.
[028] Yet another objective of the present invention is to fabricate a rail coach sidewall using series spot weld jig in less time and achieving flatness accuracy within 1mm.
SUMMARY:
[029] The present invention relates to the cost effective modular series spot weld jig to accommodate sidewalls manufacturing of different rail coach variants. This jig has been developed using fixed indexing plate, wedge assembly block and adjustable link assembly to the fixture comprises hexagonal socket head cap screw (1), dowels (2), counter sunk screw (3), flanged bolt (4) and shoulder screw (5).
[030] To accommodate any new rail coach variant having sidewall assemblies with different angles, a modular series spot weld jig has been developed which is being used for different rail coach variants from 0 to 6degree angles of sidewall.
BREIF DESCRIPTION OF THE INVENTION
[031] It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments.
[032] Figure 1 shows rail coach variant type-1 according to the present invention;
[033] Figure 2 shows rail coach variant type-2 according to the present invention;
[034] Figure 3 shows jig side view;
[035] Figure 4 shows mold point line and hinge center line being collinear;
[036] Figure 5 shows slider & indexing assemblies in the jig;
[037] Figure 6 shows jig set to different angles;
[038] Figure 7a and 7b shows flow chart according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION:
[039] The present invention provides a modular type of series spot weld jig to accommodate sidewalls manufacturing of different rail coach variants in the same jig which is cost effective. The present jig eliminates the procurement of new jigs for each angle. The present invention comprises of development of a flexible series spot weld jig making the jig suitable to manufacture rail coach models having varied angular sidewalls in the same jig without disturbance of electric current continuity which is vital in series spot welding process. This development has been made using hinge and slider indexing mechanism wherein bottom half of the jig is fixed and the upper half rotatable around the mold point line axis thereby setting to the desired angle.
[040] For better understanding of the present invention, the actual fabrication process of the sidewall is detailed below.
[041] Sidewall assembly process:
[042] Manufacturing sidewall assembly of a metro rail coach needing spot weld process is done in following 2 stages-
[043] (a) Sidewall frame structure fabrication:
[044] Sidewall frame assembly is fabricated by joining frame elements together. They were joined together using a direct spot-welding technique wherein the current path is directly through the work piece between 2 equal opposing electrodes. In this stage, jig base plate is relieved with cut-outs to aid top & bottom electrodes movement for further spot welding of structure elements. In this process, molten metal forms as the current reacts with the metal’s internal resistance and metals reach about 2000oC which is above their fusion point and the weld joint is made. Electrode must have higher melting point than the work piece. Generally, copper alloy electrodes are used due to their higher melting point as well high conductivity properties. This set up might be employed where a cosmetic weld surface is not a primary requirement (no weld indentation or heat effect)
[045] (b) Final assembly of Sidewall frame with the Panel:
[046] In this stage, sidewall frame assembly to be joined with sidewall panel (outer skin) using spot weld process where cosmetic weld is a primary requirement (no weld indentation or heat effect) since sidewall surface panel comes exterior of rail coach and play a major role in giving aesthetic look. To achieve a cosmetic surface, a series spot welding technique wherein the 2 movable electrodes are on the upper side and a large flat surface (preferable copper alloy) will be used as backup/lower electrode.
[047] This jig has been developed using fixed indexing plate, wedge assembly block and adjustable link assembly to the fixture comprises hexagonal socket head cap screw (1), dowels (2), counter sunk screw (3), flanged bolt (4) and shoulder screw (5).
[048] The present invention provides modular type series spot weld jig to accommodate any new rail coach variant having sidewall assemblies with different angles from 0 to 6 degree. Fig.1 & 2 depicts sidewall assembly’s mold point angle change possibility for different rail coach variants wherein procurement of new jigs for each angle can be avoided with this modular jig development. Fig.1 is having a straight sidewall with 0-degree sidewall angle and Fig.2 is having a mold point angle A degree sidewall angle. This angle A changes for different rail coach variants.
[049] In this type of spot welding, the current is conducted into the structure assembly by 2 electrodes touching the part from the same side and welding is done at each electrode. Copper bed acts as backup electrode and also supports sidewall panel during spot welding process. Copper material is selected for the jig base due to its high melting point and conductivity property. The current flows from 1 electrode through the top part (Sidewall structure) and into the bottom part (Sidewall panel) via backup/ lower electrode (jig copper base) to the second electrode. Since this current flow cycle repeats throughout the process, maintaining current continuity between the flat and the angular surface of the jig base is vital. Thus, maintaining current continuity between angular and flat copper base halves of the jig as shown in Fig (3) is challenging in the invention.
[050] To change the angles of the jig whenever there is a rail coach model change a hinge mechanism is used. Jig is made into 2 halves, wherein lower half is fixed and the upper half rotates about hinge center line as shown in Fig.3. The angle change that happens at mold point (point of inflection) should remain the same for different angle change of the jig as well there should be no gap between the upper half and lower half at this point to maintain current flow continuity which is vital in this series spot weld process as mentioned above. To ensure this, design of the jig has been made such that hinge centre point line and mold point line are collinear as shown in Fig.4. This successfully eliminated the problem of current flow continuity predicted to encounter in future. Two hinge assemblies have been positioned at either side of the weld jig.
[051] Slider & indexing mechanism positions the upper half to the required angle and allows the jig to suit different mold point angles. It has a wedge/slider connected to the upper half of the jig via an adjustable link assembly and is fastened to the index plate using screws. Desired angle can be achieved in the jig using this mechanism by fixing the wedge/slider assembly to the required position using fasteners as shown in Fig.3.
[052] Fig.5&6 depicts the jig set to desired angle (0degree to 6 degree) by setting the wedge/slider assembly on the index plate for respective angles. Four slider and indexing assemblies have been positioned to support the upper half of the jig via 4 no. adjustable link assemblies as shown in Fig. 5.
[053] Since current to be flown as a cycle between top electrodes and back up electrode, there should not be any leakage to the ground. To ensure the same this whole jig is fastened to a separate frame that will be fixed to the ground separating the jig and the frame by hylam sheet insulators as shown in Fig.3. Hence, Tthe sidewall assemblies for different new rails or metro coach variants with variation in angular dimensions also are manufactured in single jig with minor conversion work.
[054] With the present invention, the time to procure and place a new jig and cost to manufacture new series spot weld jigs are the achieved savings. This saving indirectly helped in reducing overall project cost of the new rail coach variants.
[055] Thus, the jig is flexible to suit to any designed angle of the sidewall. The fixture is interchangeable to suit different rail projects without compromising the quality.
[056] Manufacturing process of stainless-steel sidewall assembly of the metro rail coach involves resistance spot welding of various sheet metal parts with thin (2mm approx..) sidewall panel having window cut-outs. Side wall assembly produced will have lot of distortions due to the heat induced while spot welding (500 spots approx. for every 4 meters) and since the Sidewall panel is very thin (2mm approx.) as well having cut-outs in between at many places for windows. But, flatness accuracy of sidewall panel after welding should be within 1mm as per design requirement since Sidewall panel comes in the exterior part of the rail coach and its aesthetics is very vital. Hence, to fabricate the stainless-steel sidewall assembly without distortion and maintaining flatness of the Sidewall panel within 1mm in time is very critical and challenging.
[057] To deliver the Sidewall assembly in time and maintain flatness accuracy within 1mm, series spot welding process is used. This series spot weld process is done using a jig with copper base. This jig has a machined bed made of copper alloy material that acts as an electrode as well provides adequate support throughout the process while spot welding of sheet to the frame elements resulting in minimal distortion and achieving flatness accuracy within 1mm. This series spot weld jig is very expensive as jig top plate (backup electrode) is made of copper alloy.
[058] The geometry and dimensions of Sidewall assembly will differ for each new rail or metro coach variant. If there is no angular dimension variation in the new variant, the same series spot weld jig may be used for both the variants. But, whenever there is a change in angular dimension, a new weld jig is required for each new variant since the copper bed angle of the jig is fixed for one coach variant. However, any new procurement of series spot weld jig involves huge investment which indirectly increases the rail coach price.
[059] Prior to the development of this invention, the sidewall assemblies are manufactured in a fixed copper bed angle series spot weld jig which involves huge investment. If there are any design changes in the Sidewall angle of the coach, a new series spot weld jig with approximately same huge cost is required for that angle change.
[060] In order to overcome above listed prior art, the present invention aims to design and develop a modular type of series spot weld jig to accommodate different sidewall variants manufacturing of a rail coach in the same jig which is cost effective. The present jig eliminates the procurement of new jigs for each angle. The present invention comprises of development of a flexible series spot weld jig making the jig suitable to manufacture rail coach models having varied angular sidewalls in the same jig without disturbance of electric current continuity which is vital in series spot welding process. This development has been made using hinge and slider indexing mechanism wherein bottom half of the jig is fixed and the upper half rotatable around the mold point line axis thereby setting to the desired angle.
[061] Numerous modifications and adaptations of the system of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the true spirit and scope of this invention.
,CLAIMS:WE CLAIM:
1. A modular series spot weld jig to accommodate different sidewall variants manufacturing of a rail coach comprises into jig made of two halves, characterizing lower half is fixed and the upper half rotates about hinge center line wherein hinge center point line and mold point line are collinear such that there is no disturbance of current continuity, fixing indexing plate, wedge assembly block characterized in that wedge/slider connected to the upper half of the jig via an adjustable link assembly and is fastened to the index plate using screws and adjustable link assembly to the fixture characterized in that hexagonal socket head cap screw (1), dowels (2), counter sunk screw (3), flanged bolt (4) and shoulder screw (5) wherein jig is being used for different variants from 0 to 6 degree angles of sidewall.
2. The modular series spot weld jig, as claimed in claim 1, wherein the sidewall frame assembly is joined with sidewall panel (outer skin) using spot weld process where cosmetic weld is a primary requirement (no weld indentation or heat effect) since sidewall surface panel comes exterior of rail coach and play a major role in giving aesthetic look.
3. The modular series spot weld jig, as claimed in claim 1, wherein two movable electrodes are on the upper side and a large flat surface (preferable copper alloy) will be used as backup/lower electrode for cosmetic surface.
4. The modular series spot weld jig, as claimed in claim 1, wherein, series spot welding process is used and the current is conducted from one electrode through the top part (Sidewall structure) and into the bottom part (Sidewall panel) via backup/ lower electrode (jig copper base) to the second electrode.