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:
A METHOD OF MANUFACTURING A SIDEWALL ASSEMBLY FOR A RAIL COACH

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 Application claims priority to Indian Patent Application No. 202141018152 titled “PROCESS AND ASSEMBLY OF JIG” filed on April 20, 2021.
TECHNICAL FIELD
[002] The present subject matter described herein, in general, relates to a method of manufacturing a sidewall assembly for a rail coach.
BACKGROUND
[003] Manufacturing of a rail coach is a very complex and critical task involving various components and assemblies. Precision and accuracy are very important while building these components and assemblies. One of the major activity or process involved is welding of various components to build a final structure. However, there are many limitations of welding such as surface deformities and dimensional distortions. Manufacturing process of stainless steel sidewall assembly of the rail coach involves TIG welding and spot welding at 1400 spots of various sheet metal parts with a 2mm thick sidewall panel of 8.5 meters length (with 5 window openings). Hence in this condition, to fabricate stainless steel sidewall assembly without distortion and maintaining flatness within 2mm is very critical. This requires a series spot weld jig of 8.5 meters length which will have machined bed made of copper alloy material. The machine bed made of copper alloy is very costly and takes a lot of time to manufacture which affects the delivery of the final railway coach. Therefore, there is a need for an alternate method to manufacture the side wall assembly with required accuracy and without much cost and delay.
[004] The present subject matter discloses a method of manufacturing a sidewall assembly for a rail coach to overcome the limitations stated above.
OBJECT OF THE INVENTION
[005] An object of the present invention is to achieve the required flatness accuracy of 2 mm for production of a sidewall assembly.
[006] Another object of the present invention is to significantly reduce distortions caused due to the spot welding process.
[007] Another object of the present invention is to reduce the overall cost to manufacture the sidewall assembly.
[008] A yet another object of the present invention is to enable low volume productions of the sidewall assembly.
SUMMARY
[009] Before the present system and method 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 a method of manufacturing a sidewall assembly for a rail coach, 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.
[0010] The present subject matter discloses a method of manufacturing a sidewall assembly for a rail coach resulting in minimal distortion and as per the required flatness of the final sidewall assembly. The method comprises steps of: a) providing a plurality of cut-outs on a base panel throughout the length, b) straightening the base panel to ensure flatness of the top and bottom surfaces avoiding the distortion caused due to cut-outs, c) preparing a jig base panel by joining a plurality of base panels side by side, d) locating a plurality of frame elements on the jig base panel by a plurality of locators and clamps as per the predefined layout, e) joining the plurality of frame elements by TIG welding to make a frame structure, f) inspecting of the frame structure after the TIG welding process for flatness, g) stretching a sidewall skin panel from four corners on the jig base panel by a plurality of thrust clamps, h) positioning the frame structure over the sidewall skin panel by plurality of locators and clamps, i) spot welding the frame structure on the sidewall skin panel by gantry spot welding, and j) finishing the joining process by TIG welding the frame structure and the sidewall skin panel to manufacture the sidewall assembly with minimized distortion. The plurality of cut-outs on the base panel are configured to allow travel of welding electrodes through the base panel for spot welding.
STATEMENT OF INVENTION
[0011] The present subject matter discloses a method of manufacturing a sidewall assembly for a rail coach resulting in minimal distortion and as per the required flatness of the final sidewall assembly. The method comprises steps of: a) providing a plurality of cut-outs on a base panel throughout the length, b) straightening the base panel to ensure flatness of the top and bottom surfaces avoiding the distortion caused due to cut-outs, c) preparing a jig base panel by joining a plurality of base panels side by side, d) locating a plurality of frame elements on the jig base panel by a plurality of locators and clamps as per the predefined layout, e) joining the plurality of frame elements by TIG welding to make a frame structure, f) inspecting of the frame structure after the TIG welding process for flatness, g) stretching a sidewall skin panel from four corners on the jig base panel by a plurality of thrust clamps, h) positioning the frame structure over the sidewall skin panel by plurality of locators and clamps, i) spot welding the frame structure on the sidewall skin panel by gantry spot welding, and j) finishing the joining process by TIG welding the frame structure and the sidewall skin panel to manufacture the sidewall assembly with minimized distortion. The plurality of cut-outs on the base panel are configured to allow travel of welding electrodes through the base panel for spot welding.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] 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:
[0013] The detailed description is described with reference to the accompanying figure. The same numbers are used throughout the drawing to refer like features and components.
[0014] Figure 1 illustrates a frame structure on a flat bed, in accordance with one embodiment of the present subject matter.
[0015] Figure 2 illustrates inspection of the frame structure after the TIG welding process, in accordance with one embodiment of the present subject matter.
[0016] Figure 3 illustrates a view of a base panel with a plurality of cut-outs, in accordance with one embodiment of the present subject matter.
[0017] Figure 4 illustrates a view of a jig base panel joined by a plurality of base panels, in accordance with one embodiment of the present subject matter.
[0018] Figure 5a illustrates a view of the sidewall skin panel being stretched, in accordance with one embodiment of the present subject matter.
[0019] Figure 5b illustrates a view of the thrust clamps configured for stretching of the sidewall skin panel, in accordance with one embodiment of the present subject matter.
[0020] Figure 6 illustrates the spot welding operation on the frame structure and the sidewall skin panel, in accordance with one embodiment of the present subject matter.
[0021] Figure 7 illustrates a flow chart for method of manufacturing the sidewall assembly, in accordance with one embodiment of the present subject matter.
[0022] 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.
DETAILED DESCRIPTION
[0023] 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.
[0024] 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.
[0025] Manufacturing process of sidewall assembly of a rail coach involves TIG welding and spot welding at 1400 spots of various sheet metal parts with a 2mm thick sidewall skin panel of 8.5 meters length (with 5 window openings). Hence, to fabricate sidewall assembly without distortion and maintaining flatness within 2mm is very critical. Currently the sidewall frame structure elements are directly laid down and welded on the sidewall skin panel using mark and layout method without any support or locator. Therefore, a lot of distortion is caused in the final assembly which is then required to be corrected.
[0026] The present subject matter discloses a method of manufacturing a sidewall assembly 10 for a rail coach resulting in minimal distortion and as per the required flatness of the final sidewall assembly. The method comprises steps of: a) providing a plurality of cut-outs on a base panel throughout the length, b) straightening the base panel to ensure flatness of the top and bottom surfaces avoiding the distortion caused due to cut-outs, c) preparing a jig base panel by joining a plurality of base panels side by side, d) locating a plurality of frame elements on the jig base panel by a plurality of locators and clamps as per the predefined layout, e) joining the plurality of frame elements by TIG welding to make a frame structure, f) inspecting of the frame structure after the TIG welding process for flatness, g) stretching a sidewall skin panel from four corners on the jig base panel by a plurality of thrust clamps, h) positioning the frame structure over the sidewall skin panel by plurality of locators and clamps, i) spot welding the frame structure on the sidewall skin panel by gantry spot welding, and j) finishing the joining process by TIG welding the frame structure and the sidewall skin panel to manufacture the sidewall assembly with minimized distortion. The plurality of cut-outs on the base panel are configured to allow travel of welding electrodes through the base panel for spot welding.
[0027] Referring to figure 1, in one aspect of the invention a frame structure 20 is prepared by joining a plurality of frame elements 22 after locating them on a jig base panel 40. The frame elements 22 are first positioned and located on the jig base panel 40 by means of a plurality of locaters 42 and clamps to constrain all degrees of freedom for the frame elements 22. After finalizing the layout, the frame elements 22 are joined to each other by TIG welding to make the frame structure 20.
[0028] Referring to figure 2, the frame structure 20 is inspected manually to ensure flatness and consistent dimensions throughout the length.
[0029] Referring to figure 3, a base panel 30 is configured to be cut at various places to have plurality of cut-outs 32 of a predefined width. These cut-outs 32 enable reach of welding machine electrodes 62 to the frame elements 22 through the base panel 30. In one embodiment, the base panel 30 is configured to have a thickness of 12 mm. In absence of these cut outs, the thickness of the base panel 30 becomes hindrance for the electrodes to complete the welding process. After cutting the cut-outs 32, the base panel 30 is straightened by rolling or any other process to ensure flatness of the top and bottom surfaces and avoiding the distortion caused due to cut-outs 32. Referring to figure 4, a jig base panel 40 is prepared by joining a plurality of base panels 30 side by side.
[0030] Referring to figure 5a, a sidewall skin panel 50 is stretched from four corners on the jig base panel 40 by means of four thrust clamps 52. A piece of chain 54 is welded on four corners of the sidewall skin panel 50 and the chain 54 is pulled by the thrust clamps 52 to stretch the sidewall skin panel 50 on the jig base panel 40. Figure 5b illustrates another view of the thrust clamp 52 stretching the sidewall skin panel 50 by pulling the chain 54.
[0031] Figure 6 illustrates the spot welding operation on the frame structure 20 and the sidewall skin panel 50. The electrodes 62 of the Gantry spot welding gun 60 are configured to pass through the cut-outs 32 in the base panel 30 while performing the spot welding. Two opposing electrodes 62 of the gantry spot welding are configured to have a maximum distance of 156mm. Total depth of the sidewall assembly 10 including the base panel 30 is maintained to be within 156 mm for easy entry of the electrodes 62 of the spot welding gun 60 through the jig base panel. Additionally, the cut-outs 32 are 50mm wide in the base panel 30 which reduces the hindrance of electrodes 62 with the jig base panel or sidewall assembly enabling the spot welding operation. In the next step, TIG welding operation is performed to finish the joining process of the frame structure 20 and the sidewall skin panel 50 and thereby the sidewall assembly 10 is manufactured.
[0032] Figure 7 illustrates a flow chart for method of manufacturing the sidewall assembly (10) for the rail coach.
[0033] The sidewall assembly 10 manufactured through the claimed method is configured to achieve the required flatness accuracy of 2 mm. Further, the distortions caused due to the spot welding process is minimized. The claimed method also reduces the overall cost to manufacture the sidewall assembly as compared to the conventional methods. The claimed method is also suitable and efficient for low volume productions of the sidewall assembly 10 for a railway coach.
[0034] Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features.
[0035] Some embodiments of the subject matter enable to achieve the required flatness accuracy of 2 mm for production of a sidewall assembly.
[0036] Some embodiments of the subject matter enable to significantly reduce distortions caused due to the spot welding process.
[0037] Some embodiments of the subject matter enable to reduce the overall cost to manufacture the sidewall assembly.
[0038] Some embodiments of the subject matter enable low volume productions of the sidewall assembly.
[0039] Although implementations for the method of manufacturing a sidewall assembly have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features described. Rather, the specific features are disclosed as examples of implementation for the method of manufacturing a sidewall assembly.
,CLAIMS:
1. A method of manufacturing a sidewall assembly (10) for a rail coach wherein the method comprises steps of:
a) providing a plurality of cut-outs (32) on a base panel (30) throughout the length,
b) straightening the base panel (30) to ensure flatness of the top and bottom surfaces avoiding the distortion caused due to cut-outs (32),
c) preparing a jig base panel (40) by joining a plurality of base panels (30) side by side,
d) locating a plurality of frame elements (22) on the jig base panel (40) by a plurality of locators (42) and clamps as per the predefined layout,
e) joining the plurality of frame elements (22) by TIG welding to make a frame structure (20),
f) inspecting of the frame structure (20) after the TIG welding process for flatness,
g) stretching a sidewall skin panel (50) from four corners on the jig base panel (40) by a plurality of thrust clamps (52),
h) positioning the frame structure (20) over the sidewall skin panel (50) by plurality of locators and clamps,
i) spot welding the frame structure (20) on the sidewall skin panel (50) by Gantry spot welding, and
j) finishing the joining process by TIG welding the frame structure (20) and the sidewall skin panel (50) to manufacture the sidewall assembly (10) with minimized distortion,
wherein the plurality of cut-outs (32) on the base panel (30) are configured to allow travel of welding electrodes (62) through the base panel (30) for spot welding.