DESC:FIELD OF THE INVENTION

[001] The subject matter of the present invention, in general, pertains to axle housing coverings, and more particularly relates to a method of fabricating axle housing covers.

[002] The present complete specification is prepared by cognating the contents provisional patent specification of application numbered 201641037640 dated November 03, 2016 with the contents of the specification of patent application no. 201641037648 dated November 3, 2016. The combined contents of the present specification constitute a single invention within the meaning of the Act.

BACKGROUND OF INVENTION

[003] An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle.

[004] Rear wheel drive automotive vehicles always include axle housing covers for the rear drive wheels. Axle housing covers is formed from an upper shell secured to a lower shell by the process of welding. In particular, axle housing covers involve a dome-shaped structure that typically includes a flange. The flange is welded to the axle housing covers about the opening. The thickness of the cover in the area of the weld provides increased structural integrity to the axle housing covers about the opening. The upper and lower shells contain a center housing portion adapted to be secured to the differential for the automotive vehicle. The remainder of the shells are secured together to form the axle enclosures. The housing shells are welded together and, similarly, a wheel bearing support is secured to the free end of each axle enclosure.

[005] Axle housings covers of commercial vehicles have a large opening for receiving the differential, which connects opposing axle shafts. The opening is closed by an axle housing cover which is welded to the axle housing. Because the opening in the axle housing is large, the axle housing covers provides structural integrity to the axle assembly. Depending upon the size of the opening in the axle housing covers and other factors, an axle housing cover of a particular thickness may be desirable. Due to different axle housing cover configurations and different size openings, it is not uncommon to manufacture three or more axle housing covers, each having a different thickness.

[006] The thickness provides a weld surface to which a weld bead may be applied to connect the cover to the axle housing. The thickness of the cover that is typically desirable in the area of the perimeter edge is usually not necessary for the rest of the cover. Moreover, the axle housing cover typically has a uniform thickness. As a result, the cover is unnecessarily thick in the dome-shaped portion of the cover, which increases the weight and cost of the cover. Therefore, what is needed is an axle housing cover which provides adequate thickness in the area of the weld while providing a reduced thickness in the dome-shaped portion of the cover.

[007] Reference is made to EP2695686A1, wherein an axle housing and a method of manufacture the same has been disclosed. The axle housing may include first and second housings that have spindle portions that cooperate to define at least one spindle that may be configured to rotatably support a wheel assembly. The method steps, a sheet of material may be provided to form the first and second housings. The sheet of material may be made of a metal or metal alloy in one or more embodiments. In addition, the sheet of material may initially be provided with a substantially uniform thickness. The sheet of material may be shaped into at least one blank. The blank may be made by stamping or cutting the sheet of material. One blank may be provided to make the first housing and another blank may be provided to make the second housing. The thickness of the sheet of material or blank may be adjusted in localized regions before the blank is formed into a housing. The thickness may be adjusted by roll forming the sheet of material or blank to increase the relative thickness of at least part of the spindle portion.

[008] Reference is made to US 7,461,454 B2, wherein a method of fabricating the axle housing assembly is shown and includes the initial step of providing a first sheet of material configured and sized to produce the upper housing. The configuration of the first sheet of material or blank corresponds with the specific stamping process utilized and the overall final desired configuration of the upper housing. A second sheet of material is configured to correspond with stamping operations required to form the lower housing. The subsequent stamping operations performed are conducted to provide the final configuration of the upper and lower housings. The stamping operation forming the upper housing includes formation of the opening. The stamping operation forming the lower housing includes formation of the bowl portion.

[009] Reference is made to US 7,334,312 B2, wherein a method for forming a variable wall thickness axle or tube with internally thickened wall sections comprises extruding a tubular metal blank within an elongated die. An elongated punch pushes the blank through the die. The punch has an end abutting and pushing the blank into and through the die and an elongated portion which is spaced from the interior wall surface of the die. Movement of the punch in pushing the blank causes the blank to partially extrude forwardly through the die until stopped and then to extrude rear-wardly around the punch elongated portion through the space for forming a tube. A tubular ring is then inserted within the extruded tube at a pre-determined location and is fixed in place to provide a thick, combined tube wall and ring wall, section which extends radially inwardly of the tube. A number of spaced-apart rings may be used to provide spaced-apart thickened wall sections within the tube. The rings may be pre-formed with variable wall thickness around their circumferences for varying the thicknesses of the combined wall sections around the circumference of the tube.

[0010] Reference is made to US 2010/0013295 A1, wherein an axle body, is configured substantially as an axle pipe, which comprises a center section and at least one receiving section connected thereto for receiving an axle guide, wherein the axle body in the center section has a substantially constant wall thickness, and wherein the axle body in the receiving section, at least in some regions, has a wall thickness that is greater than the wall thickness of the center section. The axle body is fashioned as an axle pipe, comprising a center section and at least one adjoining receiving section to receive an axle guide, wherein the axle body in the center section has an essentially constant wall thickness, and the axle body in the receiving section has at least in some regions a wall thickness which is greater than the wall thickness of the center section. The axle body is advantageously fashioned as an axle pipe, though the cross sectional configuration need not necessarily be round, but instead the axle body can have any desired cross sectional configuration. Thus, in particular, the axle body can have an oval or polygonal cross sectional configuration. Preferably, however, the axle body is fashioned as an axle pipe with a round cross section surface. The axle body may be configured so that the axle body in the receiving section has a wall thickness, at least in some regions, which due to a forming process is greater than the wall thickness of the center section. The forming process can advantageously occur by means of a hot forming process, such as upsetting or forging. In addition or alternatively, the forming process can likewise be implemented by a cold forming process, such as a hydroforming or high-pressure interior forming process.

[0011] Reference is made to US 5,522,246 A, wherein a process for cold forming tubular axles comprises placing a tubular blank within an open ended die having a constricted die throat, and pushing the blank through the die throat with a punch. The punch is provided with a portion that presses the blank axially through the die throat. In addition, the punch has at least one extension which is closely fitted within the blank so that as the punch pushes a portion of the tube axially through the die throat, the extension is arranged within the die throat to form an annular space between the extension and the die throat. The punch extension is substantially elliptical in cross-section while the die throat is substantially circular in cross-section. Thus, the portion of the blank extruded through the space is formed with a substantially circular exterior wall and a substantially elliptical interior wall which provides diametrically opposing thicker wall sections and diametrically opposing thinner wall sections that are 90° offset relative to the tubular wall sections in the tubular axle. This provides an axle which may be arranged to correlate its thicker and thinner wall portions to the anticipated loads applied to the axle for reducing the weight of the axle without reducing its strength to accommodate such loads.

[0012] Reference is made to WO 2004/024366 A1, wherein a method of manufacturing an axle tube housing for a differential assembly includes heating a localized area of a one-piece tubular blan. A mandrel is inserted within the tubular blank and the localized area is then deformed to provide an increased wall thickness. A compression force is applied to the localized area of the one-piece tubular blank using a forging die to form a spindle section, wherein the spindle section closely conforms to at least one of the forging die and the mandrel. The remaining portion of the one-piece tubular blank is then cold reduced to form a carrier section.

[0013] Reference is made to US 2008/0079308 A1, which discloses an automotive axle housing having a center housing with two aligned side openings. A pair of axle tubes is secured to the center housing so that the axle tubes are aligned with the center housing side openings on opposite sides of the center housing. A pair of wheel bearing assemblies is then secured to the outer or free end of each axle tube.

[0014] Reference is made to US 2004/0103748 A1, wherein an axle housing cover includes a generally dome-shaped portion having a first thickness with the dome-shaped portion terminating in a perimeter edge. The perimeter edge has a second thickness greater than the first thickness with the perimeter edge providing a weld surface. Preferably, the second thickness is sufficiently thicker to provide adequate size and strength for the weld, which may be twice that of the first thickness. The second thickness provides a weld height greater than the first thickness. Since the dome-shaped portion has a reduced thickness, reinforcing ribs may be formed in the dome-shaped portion to provide increased structural integrity. The cover may include a flange extending radially from the cover, which provides the weld surface that is then welded to the axle housing. The axle housing cover may be formed by a stamping, hydroforming, or roll forming process. Thus it provides an axle housing cover that provides adequate thickness in the area of the perimeter edge while providing a reduced thickness in the dome-shaped portion of the cover.

[0015] Reference is made to US 4,234,120 A, wherein an axle housing assembly including a cup-shaped center housing having flattened portions which are diametrically opposed from each other. Tubular housing members, each having an end face which is circular in cross section, are connected to the flattened portions of the cup-shaped center housing by a friction weld. The tubular housing members include a connecting portion extending axially from the end face, a first frustro-conical portion interconnecting an intermediate portion to the connecting portion and a second frustro-conical portion extends axially from the intermediate portion. The cross-sectional area of the connecting portion is thicker than the first frustro-conical portion which gradually decreases in thickness toward the intermediate portion. The cup-shaped center housing defines a cavity having an opening thereto and includes a flange portion extending inwardly about the periphery of the opening and a cover plate is mounted on the inwardly extending flange portion. A spring seat member having a configuration providing first and second contact areas is welded to the tubular housing member. Additionally, there is disclosed a method of making the above-described axle housing assembly comprising the steps of forming the cup-shaped center housing from a flat plate and forming the flattened portions, forming the tubular housing members, forming openings in the flattened portions and connecting the tubular housing members to the flattened portions so that the tubular members are disposed over the openings.

[0016] Reference is made to US 3,213,531 A, wherein the axle housing of this invention comprises a pair of complementary channel-shaped stampings formed from flat stock and welded together along their longitudinal edges. A differential opening is defined in an enlarged medial portion of one of the stampings and an outwardly extending cup-shaped wall is formed in a medial portion of the other stamping. A pair of arms extending in opposite directions of each enlarged medial portion of the stampings define, when welded together, a pair of tubular axle receiving members. The medial portions define, when welded together, a differential casing with the cup-shaped wall constituting an integral cover for the differential casing.

[0017] Reference is made to US 2,167,088 A which relates to axle housings and the method of forming the same, and is more particularly directed to the formation of a rear axle housing for vehicles such as automobiles; trucks, buses, tractors and the like. It proposes heretofore to form axle housings from a tubular blank; which is centrally slotted and expanded to form a differential housing, and then swaged down along the extending arm portions and upset at the ends to form wheel bearing seats and the like. It has also been contemplated to form such housings by expanding one end of a tubular blank into a half section of a differential casing and upset the mounting I blanks to form the completed housing. It contemplates forming an axle housing from three pieces of flat sheet stock, in the case of truck and passenger car housings, and from flat blanks and a forging in the case of bus housings or other housings where the differential is offset with respect to the longitudinal center of the housing. It is a primary object of the present invention to form the differential housing, 'preferably of the banjo type, from fiat sheet stock by a series of drawing or stamping operations, the formed blank being then rolled into a hoop, flanged and having oppositely extending tapered throat portions to which are secured the arms forming the completed housing.

[0018] Reference is also made to a non-patent literature, " The Axle Housing for a Skid-Steer Loader" American Foundrymen’s Society, discloses that with axle housing in the fifth year of production, three most important lessons were learned during successful redesigning and production effort, viz., a ductile iron casting replaced the welded steel assembly with equivalent performance and an annual cost savings of $120,000; The conversion of the welded assembly to a casting produced a near-net shape piece with reduced machining requirements, weight savings and a final design that simplified final attachment of the housing to the frame; Concurrent engineering
between the foundry and the buyer was critical for meeting cost, quality, and schedule goals; The axle housing in the skid steer loader was converted to a ductile iron casting with a cost savings of 15%, achieved by: Improved near-net shape that reduced machining operations and Casting in sand for low cost, high volume, just-in-time production.

[0019] Reference is also made to a non-patent literature, " Stress Distribution Analysis of Rear Axle Housing by using Finite Elements Analysi" by Khairul Akmal Shamsuddin, Mohd Syamil Tajuddin, Megat Mohd Amzari, Megat Mohd Aris and Mohd Nurhidayat Zahelem ‘discloses that housing are manufactured by the stamp welding process from 7 mm thick sheets made from a micro alloyed fine grained, hot formable normalized structural steel S460N. Material number is 1.8901, EN 10025 – 3: 2004 technical delivery conditions for normalized / normalized rolled weld able fine grain structural steels. Weldable fine grain structural steels are in compliance with the EN 10025-3:2004 standard, which defines four levels of mechanical properties. Each grade can be obtained with guaranteed impact properties at -20°C (N grades), or for low temperature applications at -50°C (NL grades). Weld able fine grain structural steels are either normalized or obtained by normalizing co-lamination and thus keep their mechanical properties if the welded parts are normalized. These steels are used for welded parts that have to withstand high levels of strain. In order to take effects on the applied process on mechanical properties into FE analysis, each value of mechanical properties of this material was defined before simulation. The material was defined as structural steel with constant variable.

[0020] Reference is also made to a non-patent literature, "Rear Axle Assembly Construction and Operation" The Goodheart-Willcox Co., Inc., discloses a rear axle housing associated with solid-axle rear suspension consists of a central housing, or differential carrier, and axle tubes, which enclose the drive axles and extend to the rear wheels. (Vehicles with independent rear suspension will not have axle tubes.) Rear axle housings will have a vent to relieve pressure build-up. They will also have oil drain and fill plugs. Most rear axle housings are made of steel. Steel axle tubes are pressed and welded into the housing or are cast integral with the housing. The axle tubes usually have an integral flange at the outer end. The flange provides a mounting surface for the brake backing plate and an axle retainer plate.

[0021] However, in view of the above existing techniques, it is observed that after the entire axle housing covers has been assembled and welded, the bearing supports and differential attachment ring are often not precisely aligned with each other due to distortions caused by welding. Therefore the conventional axle housing covers typically suffer from numerous disadvantages. Such as, axle housing covers needing numerous components need not only be properly positioned relative to each other, but secured together, typically by welding, adding additional expense to the manufacturing expense of the axle housing. Moreover, axle housing covers require numerous machining operations, which are not only costly, but also time consuming to perform. Most importantly, existing forming process is not able to process adequate thickness in axle housing cover and the yield is only 65 % with the existing forming process.

[0022] Thus, in view of the drawbacks of existing axle housing covers it is realised that there is a dire need for an improved method of forming axle housing covers through Flow Forming Process so as to establish the adequate thickness of axle housing cover and effective material optimization.

SUMMARY OF THE INVENTION

[0023] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[0024] An object of the present invention is to provide a method for fabricating an axle housing cover.

[0025] Another object of the present invention is to provide a method for manufacturing of axle housing cover with flat strip sheet converted to cylinder and forming through flow forming process to fabricate the axle housing cover and material optimization, it works through material gathering through spinning process.

[0026] Yet another object of the present invention is to provide a method for fabricating an axle housing cover with pipe cut to length and forming through flow forming process to establish the axle housing cover with adequate thickness and material optimization, it works through material gathering through spinning process.

[0027] Another object of the present invention is to eliminate cover weld failure and have lesser thickness in the axle housing cover wherever the strength is minimum.

[0028] Yet another object of the present invention is to provide a method for fabricating an axle housing cover using technology called material gathering through spinning process.

[0029] Still another object of the present invention is to provide a design of axle housing covers where the cover geometry has been changed to smooth transition thickness from fixed thickness to variable thickness.

[0030] Accordingly, in one aspect of one embodiment, the present invention provides a method for forming an axle housing cover using material gathering through spinning process, wherein said method comprising the steps of: Cutting a sheet to a desired length to obtain a flat strip sheet; Coiling and flattening said flat strip sheet and thereby joining edges of said sheet to form a rounded shaped structure of said sheet; flaring and forming said rounded shaped structure of said sheet by using a flow forming process and obtaining a dome-shaped portion.

[0031] In another aspect, the present invention provides an axle housing cover fabricated using either of the method as mentioned above, wherein said cover having a generally dome-shaped portion having a first thickness, second thickness and a third thickness, said dome-shaped portion terminating in a perimeter edge having a second thickness greater than said first thickness and third thickness greater than the second thickness.

[0032] In one aspect of an alternate embodiment, the present invention provides a method for forming an axle housing cover, wherein said method comprising the steps of: Cutting a pipe to a desired length; and Flaring and forming by using a flow forming process a dome-shaped portion to form said housing cover.

[0033] Thus, the present invention provides improvement in the existing axle housing cover design techniques and executing through using technology called material gathering through spinning process.

[0034] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0035] Figure 1 illustrates steps of process execution of material gathering through spinning process, according to one embodiment of the present invention.

[0036] Figure 2 illustrates process execution according to an alternate embodiment of the present invention.

[0037] Figure 3 (a) illustrates existing axle housing cover throughout the cover and Figure 3(b) illustrates proposed axle housing cover design with adequate thickness throughout the cover, according to both embodiment of the present invention. Figure 3(c) illustrates an axle design combining existing and proposed axle housing covering design.

[0038] Figure 4 illustrates the Design Execution through FEA Results for the axle housing cover designs according to both embodiment of the present invention.

[0039] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0040] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0041] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0042] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0043] It is to be understood that the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0044] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0045] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0046] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or component but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0047] In the present invention, “material gathering through spinning process” technology will revolutionize the field of automobile industries. It aids in providing smooth transition thickness from single thickness to variable thickness. This in turn may lead to stresses reducing drastically due to smooth transition thickness, eliminating cover weld field failure and the product reliability also improves. The proposed method and system is cost effective as it can reduce the input material required that in turn improves the productivity.

[0048] In one embodiment, as shown in figure 1, the material gathering through spinning process involves the steps of receiving cut sheets, cut to length. The metallic strip can be then coiled and flattened with its ends flash-butt welded. Then weld trimming, planishing and ends cutting may be performed. Then comes re-rounding of the metal strip which can be followed by flaring and pre-forming of the cylindrical metal strip. Then the cylindrical metal strip may be flow formed. At the end of this process, the final thickness of the axle housing cover starts from 10mm and taper's uniformly to 4-5 mm.

[0049] In the embodiment, the steps as illustrated in figure 1 is as follows:
• Sheet Cut to length: The present invention discloses system and method for making an axle housing cover with sheet as input and cut to length;
• Coiling and Flattening: Sheet will be coiled , flattened and rolled;
• Flash Butt Welding: The edges of the sheets will be flash butt weld to join the ends;
• Weld trimming, Planishing and ends cutting: In this operation weld projections and splatters will be cut and cleaned;
• Rerounding: In this operation, any deformation caused during welding will be corrected by re rounding;
• Flaring and Preforming and Flow forming: Flaring and forming through flow forming process to establish the axle housing cover and material optimization, it works through material gathering through spinning process;
• Joining: The gap formed will be filled with the plug by welding or they any other process;
• End of process –Final axle housing cover will be obtained

[0050] In the embodiment, the flat strip sheet is converted into cylinder and forming through flow forming process to fabricate the cover with adequate thickness and material optimization, it works through material gathering through spinning process.

[0051] The method of axle housing cover eliminate cover weld failure and have lesser thickness wherever the strength is minimum.

[0052] In an alternate embodiment, as shown in figure 2, the present invention provides method of making an axle housing cover with pipe cut to length, flaring and forming through flow forming process. The method works through Material gathering through spinning process.

[0053] In the alternate embodiment, as shown in figure 2, the present invention provides a method of forming axle housing cover of uneven/variable thickness by material. It works through material gathering through spinning process. The method comprising the following steps:
• Pipe-Cut to length: The present invention discloses system and method for making an axle housing cover with Pipe as input and cut to length;
• Coiling and Flattening: This process ensures required flattening required for butting on housing
• Flow forming: Flaring and forming through flow forming process to establish the axle housing cover with adequate thickness and material optimization, it works through material gathering through spinning process Flash Butt Welding;
• Welding: The gap formed will be filled with the plug by welding;
• End of process –Final axle housing cover will be obtained.

[0054] Thus, in both the embodiments, improvement in the existing axle cover design techniques is achieved and executing through using technology called material gathering through spinning process.

[0055] In both embodiment, the method will eliminate the cover weld failure and can have lesser thickness wherever the strength is minimum.

[0056] In both embodiment, the cover geometry will be changed to smooth transition thickness from single thickness to variable thickness.

[0057] In both embodiment, axle load distribution to the axle housing cover will act only 25% of the Total Cover Depth and rest of 75 % of the area it just acts as a supporting member.

[0058] In both embodiment, at the end of the fabrication process, as shown in figure 3(b) and 2(c), the final thickness of the axle housing cover will starts from 10mm and tapers uniformly to 4-5 mm but not limited to it. Thus, the axle housing cover will have a variable thickness design as compared to a fixed thickness design of the prior art axle housing cover as shown in figure 3(a).

[0059] In both embodiment, at the end of this process, the final thickness of the axle housing cover will starts from 10mm and tapers uniformly to 4-5 mm but not limited to it.

[0060] In both embodiment, narrow down the thickness to smooth transition from 10mm to 4mm, but not limited to it, for better load scattering and improvement in the stresses through FEA results as shown in figure 4.

[0061] In both embodiment, reference is made to figure 4, the below table 1 shows drastically improvement in stresses with Material Optimization process and thereby resulting in the improvement in stresses through FEA results during the fabrication of axle housing cover:

Stress Location Location @12’clock Location @4’clock Location @8’clock
existing Design 320 MPA 395 MPA 412 MPA
current Design 247 MPA 327 MPA 345 MPA
% of Stress Reduced 22 % 17 % 16 %
Table 1

[0062] Some of the benefits of the present invention are mentioned below:
1. According to the embodiments of the present invention, stresses come down drastically due to Smooth transition thickness.
2. The present invention eliminates cover weld Field failure and Product reliability improves.
3. The present invention is cost effective.
4. The present invention reduces the in Input material to be used.
5. The present invention gives rise to improvement in productivity

[0063] Although an improved system and method of fabricating axle housing covers has been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations of the system and method of fabricating axle housing covers.
,CLAIMS:1. A method for forming an axle housing cover using material gathering through spinning process, wherein said method comprising the steps of:
Cutting a sheet to a desired length to obtain a flat strip sheet;
Coiling and flattening said flat strip sheet and thereby joining edges of said sheet to form a rounded shaped structure of said sheet;
flaring and forming said rounded shaped structure of said sheet by using a flow forming process and obtaining a dome-shaped portion.

2. The method as claimed in claim 1, wherein said edges of said sheet are flash butt weld to join ends of said flat strip sheet.
3. The method as claimed in claim 2, wherein after the step of flash butt welding, said weld projections and splatters are cut and cleaned.
4. An axle housing cover fabricated using a method as claimed in claims 1-3, wherein said cover having a generally dome-shaped portion having a first thickness, second thickness and a third thickness, said dome-shaped portion terminating in a perimeter edge having a second thickness greater than said first thickness and third thickness greater than the second thickness.
5. The axle as claimed in claim 4, wherein said thickness of said cover starts with 10mm and tapers uniformly with thickness 4-5mm.