DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
SPOT-WELDING PROCESS FOR MANUFACTURING SIDE WALL STRUCTURE OF RAIL BOGIE

Applicant:
BEML Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
BEML Soudha, 23/1, 4th Main,
Sampangirama Nagar, Bengaluru - 560 027,
Karnataka, India

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS REFERENCE TO RELATED APPLICATION AND PRIORITY
[001] The present invention claims priority from Indian patent Provisional Application 202141029012 filed on 29th June, 2021.

TECHNICAL FIELD
[002] The present subject matter described herein, in general, relates to a spot-welding process for manufacturing a side wall structure of a rail bogie, and more specifically to spot-welding process for pre-cambered structures of the side wall.

BACKGROUND OF THE INVENTION
[003] Spot-welding process is used basically for welding two or more metal sheets together by applying pressure and heat from an electric current to the weld area. It is a modern welding technique where filler material is not required. The spot-welding process uses two shaped copper alloy electrodes to concentrate welding current into a small "spot" and to simultaneously clamp the sheets together. The said process may also be used for welding of thin frame structures like side wall structures of vehicles. There are many distortions occurring due to welding process which has to be taken into consideration while designing the required structure. Hence, there is need to develop a process that gives required structure with optimized steps to be performed with less effort and less expenses.

OBJECTS OF THE INVENTION
[004] Main objective of the present invention is to provide a spot-welding process with optimized steps to perform welding of side wall assembly of a rail bogie.

[005] Another object of the present invention is to segregate a side wall assembly into sub-assemblies for ease of welding.

[006] Another object of the present invention is to provide pre-cambering to sub-assemblies of a side wall assembly for obtaining required dimensions of a side wall.

SUMMARYOF THE INVENTION
[007] Before the present process are described, it is to be understood that this application is not limited to the particular machine or an apparatus, and methodologies described, as there can be multiple possible embodiments that are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to spot-welding process for side wall assembly of rail, and the aspects are further elaborated below in the detailed description. This summary is not intended to identify essential features of the proposed subject matter nor is it intended for use in determining or limiting the scope of the proposed subject matter.

[008] The present invention relates to a spot-welding process for manufacturing a side wall structure of a rail bogie comprising steps of: mounting plurality of sub-assemblies on an assembly jig by locators wherein degree of freedom of the sub-assemblies are configured to be constrained by plurality of clamps, performing spot-welding operation on the sub-assemblies configured to form a side block frame, dismounting the side block frame from the assembly jig, pre-cambering of a welding stand with clamping arrangement configured to mount the side block frame, performing welding of seat bracket to the side block frame on the said pre-cambered welding stand, performing reverse welding on the side block frame on the said pre-cambered welding stand, checking the side block frame for required dimensions and for required flatness, mounting a copper bed on a jig and clamping the copper bed for series spot-welding, mounting a side block panel on the copper bed and then mounting the side block frame on the side block panel for positioning in the jig and constraining the degree of freedom of all the components, performing the spot weld operation for joining the side block frame with the side block panel to form a side wall assembly and inspecting the side wall assembly for the required dimensions and for the required flatness. Further, the sub-assemblies are configured to be a window upper assembly, a window lower assembly and a door post assembly to form the side block frame wherein the raw material used to for the sub-assemblies may be SUS301L-ST. The spot-welding process for manufacturing a side wall structure of a rail bogie, wherein the said spot-welding is configured to establish WPS (welding procedure specifications) quality of weld. Furthermore, the assembly jig is configured to be designed based on the side block frame dimensions.

BRIEF DESCRIPTION OF THE DRAWINGS
[009] The foregoing summary, as well as the following detailed description of embodiments, is better understood when read in conjunction with the appended drawing. For the purpose of illustrating the disclosure, there is shown in the present document example constructions of the disclosure, however, the disclosure is not limited to the specific methods and apparatus disclosed in the document and the drawing:

[0010] The detailed description is described with reference to the accompanying figure. In the figure, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawing to refer like features and components.

[0011] Figure 1 illustrates a side wall of a rail bogie, in accordance with present invention.
[0012] Figure 2(a) illustrates a side block frame of a side wall, in accordance with present invention.
[0013] Figure 2 (b) illustrates a side block panel of a side wall, in accordance with present invention.

[0014] Figure 3 (a) illustrates a window upper assembly of a side wall assembly, in accordance with present invention.

[0015] Figure 3 (b) illustrates a window lower assembly of a side wall assembly, in accordance with present invention.

[0016] Figure 3 (c) illustrates a door post assembly of a side wall assembly, in accordance with present invention.

[0017] Figure 4 (a) illustrates a side block frame after assembling sub-assemblies, in accordance with present invention.

[0018] Figure 4 (b) illustrates an assembly jig for mounting a side wall frame, in accordance with present invention.

[0019] Figure 4 (c) illustrates a spot-welding of a side wall frame, in accordance with present invention.

[0020] Figure 4 (d) illustrates a seat bracket welding of a side wall frame, in accordance with present invention.

[0021] Figure 4 (e) illustrates a reverse welding of a side wall frame, in accordance with present invention.

[0022] Figure 4 (f) illustrates a cold straightening of a side wall frame, in accordance with present invention.

[0023] Figure 5 illustrates a behavior of side wall assembly after welding, in accordance with present invention.

[0024] Figure 6 illustrates a development of welding stand for seat bracket welding of side wall assembly, in accordance with present invention.

[0025] Figure 7 illustrates a pre-camber incorporated in a seat bracket welding stand, in accordance with present invention.

[0026] Figure 8 (a) illustrates a copper bed for a side wall assembly, in accordance with present invention.

[0027] Figure 8 (b) illustrates a side block panel mounted on a copper bed, in accordance with present invention.

[0028] Figure 8 (c) illustrates a side block frame to be mounted on a side block panel, in accordance with present invention.
[0029] Figure 9 illustrates a process flow chart, in accordance with present invention.

[0030] The figure depicts various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

[0031] REFERRAL NUMERALS:
Element Description Reference Numeral
Side Wall 100
Side Block Frame 202
Side Block Panel 204
Window Upper Assembly 302
Window Lower Assembly 304
Door Post 306
Window Frame 308
Assembly Jig 400
Welding Stand before Development 602
Welding Stand after Development 604

DETAILED DESCRIPTIONOF THE INVENTION
[0032] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising", “having”, and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, systems and methods are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.

[0033] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.

[0034] Generally, in India, projects like manufacturing of railways includes an importing of materials like bogies and other parts. Now, metro rail projects are in demand, and it costs huge amount. So, BEML has proposed to develop the bogies indigenously using different raw materials and based on various trials and errors, they have proposed to form a manufacturing of side wall of the bogie by including a spot-welding process. While performing spot-welding, a WPS (welding procedure specifications) has to meet international quality requirements for maintaining a good quality of work. Also, indigenous manufacturing will reduce cost of manufacturing.

[0035] In an embodiment, the side wall of the bogie may comprises 6 middle blocks and 4 side blocks. The side wall structure of the proposed invention comprises two basic components as a side block frame and a side block panel wherein both the components may be welded together to form the side wall of the bogie. Further, the side block frame may configured to be formed by “A” grade spot-welding and the side block panel may configured to be formed by series spot-welding.

[0036] Referring to figure 1, a side wall (100) of a rail bogie is illustrated. In an embodiment, the side wall of bogie may be configured with 3 middle blocks and 2 end blocks. Apart from above-mentioned blocks, other elements like cantrail assembly, upper panel, door cover and rain gutter along with minor sub-assemblies like door way entrance frame, door way upper rocker rail and door way bottom rocker rail may be provided while assembling the side wall.

[0037] Referring to figure 2 (a) and figure 2 (b), a side block frame (202) and a side block panel (204) are shown respectively. The side block frame (202) and the side block panel (204) may be welded together to form a side wall structure.

[0038] Referring now to figure 3 (a), figure 3 (b) and figure 3 (c), sub-assemblies of the side block frame (202) are depicted. Figure 3 (a) shows a window upper assembly, figure 3 (b) shows a windows lower assembly and figure 3 (c) shows a door post assembly. The sub-assemblies may be welded together to form a complete side block frame (202) for the side wall assembly (100). The side block frame (202) may be divided into number of sub-assemblies for ease of welding and for achieving quality weld. In an embodiment, a raw material used to for the sub-assemblies may be SUS301L-ST wherein the sheet comprises a thickness of 1.2 mm, 1.5 mm, 2 mm and the sheets may be laser cut to form the required sub-assembly. Further, dimensions of each sub-assembly may be predefined based on required side wall of a bogie.

[0039] Referring to figure 4 (a), the side block frame (202) of the side wall assembly (100) of rail vehicle is shown. The side block frame (202) may be formed by welding together the above-mentioned sub-assemblies. The said welding may configured to be a spot-welding. For the welding purpose, the sub-assemblies may be mounted in an assembly jig (400) (refer figure 4 (b)). Further, after performing the spot-welding (figure 4 (c)), the side block structure may be dismounted from the jig (400) and subjected to seat bracket welding (figure 4 (d)), reverse welding (figure 4 (e)) and cold straightening (figure 4 (f)) operations.

[0040] Referring now to figure 5, a behavior of side block frame (202) after performing the spot-welding is shown. After spot-welding, the frame may undergo distortion and required dimensions of the frame may not be achieved. In the figure, a blue line indicates a required profile, and a red line indicates a distorted profile of the side block frame (202) after the spot-welding operation.

[0041] Referring to figure 6, a development in a welding stand for mounting the side block frame (202) is depicted. The welding stand has been modified to provide clamping facilities for welding the side block frame (202). Further, the welding stand may be incorporated with pre-camber to minimize the distortion in the side block frame (202) while welding. Further, the figure 7 shows the pre-camber provided to the welding stand wherein the green line shows a camber to be set in the welding stand (202).

[0042] Referring to figure 8 (a), 8 (b) and 8 (c), loading of the side block panel (204) in copper bed and a positioning of the side block frame (202) with the side block panel (202) is shown. Figure 8 (a) shows the copper bed in clamping position and the side block panel (204) may be mounted on the copper bed as shown in figure 8 (b). Further, the side block frame (202) may be positioned on the side block panel (204). In an embodiment, the side block panel (204) may be configured from SUS301L DLT material. Further, a series spot-welding may be performed on the copper bed and the side block frame (202) and the side block panel (204) may be fixed/connected to each other. In an embodiment, the series spot-welding may be performed by series spot-welding machine. Furthermore, the said welding may be established meeting a tensile shear, nugget diameter, and section test requirements for joints.

[0043] Referring to figure 9, a process flow chart of the present invention is shown. The process of the present invention described herein is a spot-welding process for manufacturing a side wall structure of a rail bogie comprising steps of: mounting plurality of sub-assemblies (302, 304, 306) on an assembly jig (400) by locators wherein degree of freedom of the sub-assemblies are configured to be constrained by plurality of clamps, performing spot-welding operation on the sub-assemblies (302, 304, 306) configured to form a side block frame (202), dismounting the side block frame (202) from the assembly jig (400), pre-cambering of a welding stand (604) with clamping arrangement configured to mount the side block frame (202), performing welding of seat bracket to the side block frame (202) on the said pre-cambered welding stand (604), performing reverse welding on the side block frame (202) on the said pre-cambered welding stand (604), checking the side block frame (202) for required dimensions and for required flatness, mounting a copper bed on a jig and clamping the copper bed for series spot-welding, mounting a side block panel (204) on the copper bed and then mounting the side block frame (202) on the side block panel (204) for positioning in the jig and constraining the degree of freedom of all the components, performing the spot weld operation for joining the side block frame (202) with the side block panel (204) to form a side wall assembly (100) and inspecting the side wall assembly (100) for the required dimensions and for the required flatness.

[0044] The said sub-assemblies are configured to be a window upper assembly (302), a window lower assembly (304) and a door post assembly (306) to form the side block frame (202) wherein the raw material used to for the sub-assemblies (302, 304, 306) may be SUS301L-ST. Further, the pre-camber of the welding stand is configured to be based on required dimensions of the side wall assembly (100). Furthermore, the said spot-welding is configured to establish WPS (welding procedure specifications) quality of weld.
,CLAIMS:

1. A spot-welding process for manufacturing a side wall structure of a rail bogie comprising steps of:
mounting a plurality of sub-assemblies (302, 304, 306) on an assembly jig (400) through locators for constraining degrees of freedom of the plurality of sub-assemblies (302, 304, 306) by plurality of clamps;
performing spot-welding operation on the sub-assemblies (302, 304, 306) to form a side block frame (202);
dismounting the side block frame (202) from the assembly jig (400);
pre-cambering of a welding stand (604) with clamping arrangement to mount the side block frame (202);
welding the seat bracket to the side block frame (202) on the said pre-cambered welding stand (604);
welding on the side block frame (202) on the said pre-cambered welding stand (604) from reverse side;
checking the side block frame (202) for required dimensions and for required flatness;
mounting a copper bed on a jig and clamping the copper bed for series of spot-welding;
mounting a side block panel (204) on the copper bed and then mounting the side block frame (202) on the side block panel (204) for positioning in the jig and constraining the degree of freedom of all mounted components;
spot welding the side block frame (202) with the side block panel (204) to form a side wall assembly (100); and
inspecting the side wall assembly (100) for the required dimensions and for the required flatness.

2. The spot-welding process for manufacturing the side wall structure of the rail bogie as claimed in claim 1, wherein the sub-assemblies are a window upper assembly (302), a window lower assembly (304) and a door post assembly (306) to form the side block frame (202).

3. The spot-welding process for manufacturing the side wall structure of the rail bogie as claimed in claim 1, wherein the pre-camber of the welding stand is based on required dimensions of the side wall assembly (100) to be manufactured.

4. The spot-welding process for manufacturing the side wall structure of the rail bogie as claimed in claim 1, wherein a raw material used for the sub-assemblies (302, 304, 306) is SUS301L-ST.

5. The spot-welding process for manufacturing the side wall structure of the rail bogie as claimed in claim 1, wherein the said spot-welding operation is performed to establish WPS (welding procedure specifications) quality of weld.

6. The spot-welding process for manufacturing the side wall structure of the rail bogie as claimed in claim 1, wherein the assembly jig (400) is configured to be designed based on the side block frame (202) dimensions.