FORM -2
THE PATENTS ACT, 1970
(39 OF 1970)
COMPLETE SPECIFICATION
(See Section 10)
TITLE OF INVENTION "Automotive Rear Axle Housing"
(a) Bharat Forge Ltd. (b) a company registered under the companies Act 1956 and (c) having its office at Mundhwa, Pune411 036, Maharashtra India
The following specification particularly describes the nature of the invention and the manner in which it is performed

Field of Invention
The present invention relates to automotive rear axle housing. In particular the present invention relates to automotive rear axle housing and method of manufacturing the same with effective utilisation of raw material without compromising on the fatigue, static, specific strength and performance of the rear axle housing.
Background of Invention
Axle is an imperative chassis component of any automobile. The axles are at the front and rear side of the vehicle, conventionally known as front and rear axle. The axles in vehicles are primarily classified as live or dead axles. The dead axle supports vehicle and provides mounting for wheel assembly. Automotive rear axle is the chassis component on which about 2/3rd of vehicle weight acts. In case of live axle shaft drives wheels connected to it. The rear axle essentially comprises of differential mechanism housed in axle housing. The housing may be of one piece of split type construction. In later, it is formed from sheet metal. Since the axle carries substantial weight of the vehicle, the entire assembly is considerably heavy. However, it is always desirable and important to enhance specific strength of the components such as axle housing. This reduces weight of the component, enhances vehicle performance and saves raw material.
Conventional manufacturing method of split rear axle housing is blank cutting, forming to produce channel & welding two channels together to manufacture entire axle housing. It is to be noted that the said blanks are cut out of a sheet metal plate of predefined size using predominantly gas or plasma cutting. It is important to have effective layout of blanks in the parent sheet metal plate so as to cut as many blanks as possible from the said sheet metal plate and reduce material wastage and increase material utilization, known as yield.
In existing blank design triangular projections are present due to which with large size of plate 4 blanks can be cut. This layout results in about 70 % utilization of material (Yield) thereby leading to about 30% wastage of material. By considering

mass production of rear axle housing, substantial raw material is wasted with conventional blank layout. There is need to effectively utilize material and manufacture rear axle housing without compromising on the fatigue strength, rigidity and specific strength. The rear axle and axle housing related inventions are reported in prior art. It is mentioned hereunder.
United States Patent 3673888 discloses an axle housing for a motor vehicle is composed of two half cylinders rolled from a flat plate of uniform thickness to varied thicknesses from one end to the other, and then die pressed to half cylinder shape and then welded together. This produces a low cost, lightweight housing having adequate strength in the load bearing areas.
Japanese Patent JP2009150479 discloses invention to prevent the occurrence of cracks at the welded portion of a rear axle housing and a cover without using a special welding device, with regard to a structure of welding the cover to the rear axle housing provided on a vehicle and its welding method. The solution to this problem is disclosed wherein in the structure, the cover for closing a hole part is welded to a hole part peripheral edge at the center part of the rear axle housing. The edge parts of the cover are continuously welded to the hole part peripheral edges from the outside of the rear axle housing, and required portions of the edge part of the cover are spot welded on the hole part peripheral edge inside the rear axle housing.
United States Patent 5442977 discloses a differential axle housing which is particularly adapted for use in a fork lift and by which productivity is improved and which can be produced in a manner minimizing the waste of materials. Its differential housing has a generally cylindrical roll-forged ring portion having open ends along an axis, and a cover closing one of the open ends. A pair of straight cylindrical flange portions, preferably roll-forged, is attached in diametrically opposite relation to each other on the peripheral wail of the ring portion, each surrounding an axle opening therein. These elements are welded to the ring portion after being individually formed. Thus, the differential housing is produced. A pair of axle tubes is then shrink-fit and welded to the respective flange portions,

and fitting brackets for receiving the mast pivot brackets of a fork lift mast are attached to the respective of the axle tubes.
United States Patent 7461454 discloses an axle assembly includes an upper and lower housing joined to form a chamber for a differential gear assembly. The upper and lower housings are fabricated by a method including the steps of forming the upper housing from a first sheet of material and forming the lower housing from a second sheet of material. The upper housing includes an opening for the differential gear assembly and the lower housing includes a bowl portion disposed opposite the opening. The upper and lower housings are joined by a weld to from the axie housing. The lower housing includes leg portions that form a single unified structure with the bowl portion to improve structural rigidity and -simplify assembly.
United States Patent 5297855 discloses a banjo-type axle housing includes a hollow central member having a pair of hollow tubes extending outwardly therefrom. Forwardly and rearwardly facing openings are formed in the central member, each having triangularly shaped side portions located adjacent to the tubes. In a first embodiment, a pair of triangularly shaped support plates are disposed within the side portions and secured to the central member so as to completely close them. In a second embodiment, a pair of modified baffle plates is provided, each including a central baffle portion having an opening formed there through and a pair of triangularly shaped side portions formed integrally with the central baffle portion. The side portions are bent so as to extend generally perpendicular relative to the central baffle portion. The modified baffle plates are secured to the central member of the axle housing and perform the functions of the separate baffle plates and side portions of the first axle housing
United States Patent 3793703 A rear axle housing comprises two longitudinal sections welded together, each section being produced by the process of first preshaping a rough billet into the general configuration of a forging blank, forging the blank in several steps into a flat shaped member and then forging the member into the general shape of the housing section. A minimum amount of machining is required to remove the excess material and finish the housing. A special

apparatus is provided for performing the intermediate steps of forging the preformed billet into a shaped forging blank.
United States Patent Application 20070062241 discloses a method for manufacturing a one piece axle tube housing with an integral spindle includes providing a tube blank, providing the blank with a region of increased thickness, inserting a mandrel-having a reduced diameter profile, passing a reducing die over the tube to conform the tube to the shape of the mandrel; and extraction of the mandrel from the tube to cause outward deformation of the tube at specific locations. A further swaging step may be used to form the final spindle structure. Representative Image:
United States Patent 7681426 discloses a method for manufacturing a one piece axle tube housing with an integral spindle includes providing a tube blank, providing the blank with a region of increased thickness, inserting a mandrel having a reduced diameter profile, passing a reducing die over the tube to conform the tube to the shape of the mandrel; and extraction of the mandrel from the tube to cause outward deformation of the tube at specific locations. A further swaging step may be used to form the final spindle structure.
United States Patent 3858429 discloses a rear axle housing comprises two longitudinal sections welded together, each section being produced by the process of first preshaping a rough billet into the general configuration of a forging blank, forging the blank in several steps into a flat shaped member and then forging the member into the general shape of the housing section. A minimum amount of machining is required to remove the excess material and finish the housing. A special apparatus is provided for performing the intermediate steps of forging the preformed billet into a shaped forging blank.
Japanese Patent JP2003191708 discloses invention associated to reduce the weight of a radius rod bracket in a rear axle housing of a commercial vehicle without sacrificing its rigidity. The solution is provided in a trunnion-suspension type rear 2-axle vehicle, upper radius rod brackets 8 and 8' and lower radius rod brackets 11 and 11' are integrally cast to the rear axle housing 1, a recess part is

formed respectively on mutually opposing faces of the upper radius rod brackets 8 and 8' in the car width direction, while a recess part is formed respectively on mutually opposed faces of the lower radius rod brackets 11 and 11' in the car width direction, and the cross section of each of the brackets 8, 8', 11 and 11' is substantially in the U-shaped.
Japanese Patent JP2004217074 discloses rear axle housing capable of reducing the weight in a large scale while securing enhanced deformation strength of each pair of boss parts in a seat part. This rear axle housing 3 is provided with a seat part 4 forming a receiving seat of a leaf spring on both end upper surfaces along the longitudinal direction, and can fasten a central part of the leaf spring with respect to the seat part 4 by a pair of U bolts in the front and behind. The pair of boss parts 14 for fastening the U bolt are respectively provided in the front and the behind of the seat part 4, and a wall part between the respective pairs of the boss parts 14 are formed to be inclined so that an upper part of the wall part protrudes outward in the vehicle longitudinal direction and the wall part gradually retreats inward in the vehicle longitudinal direction as going to the lower part. The portion formed to be inclined is constituted so as to function as a bag shaped rib 17.
Japanese Patent JP2003191706 discloses invention related to reduce the weight of a rear axle housing in a commercial vehicle. This rear axle housing 1 is integrally cast with a spherical graphite cast iron material, and the thickness of each of a differential carrier mounting part 5 in the rear axle housing 1, and an upper and lower part of an arm part 3 to which a bracket 6 for connecting an upper radius rod, a bracket 7 for connecting a lower radius rod, a slide seat 8 and a side thrust bracket 9 are mounted, is formed 2 to 4 times larger than the thickness of a vertical wall part in the rear axle housing 1.
Japanese Patent JP08002207 discloses invention related to make a side gap properly adjustable, and further to facilitate the adjustment as well as to make improvements in steering stability. Two adjusting bolts 15 and 15 are made projectable or retractable of its tip to or from side gaps G and G to be formed in space between rear leaf springs 31, 31 and leaf spring brackets 12, 12 and then pierced through and screwed in these leaf spring brackets 12 and 12, and

subsequently the bolts are locked to the leaf spring brackets 12 and 12 by a locking nuts 16 and 16.
Japanese Patent JP2000264085 discloses invention to use parts commonly for improving production efficiency by composing rear axle housings to be installed on the right and the left of a transmission case in the same form. A right and a left rear axle housings 32L, 32R are formed to be symmetric on the right and left to a center line 47 connecting a support part 45 of a rear axle shaft to a support part 46 of a wheel disc shaft, and installation parts 48, 49 are provided at symmetric positions on the right and the left. Both installation parts 48, 49 are formed in the same form, an installation hole 51 for a brake arm is bored in either one installation part 48, 49, and an installation hole 50 for a differential lock arm is bored in the other installation part 48, 49. The right and the left rear axle housings 32L, 32R can thus be composed in the same form.
Japanese Patent JP06182473 discloses an apparatus and method for forming a rear axle housing of a vehicle using a single steel tube. This method is for forming and producing the rear axle housing of the vehicle from the integral steel tube. This method involves cutting a longitudinally through opening 2 in the center of the steel tube 1, expanding the opening 2 with an expanding device and after expansion, roll-pressing or pressing the wall 9' of the steel tube 1 into the required form. The apparatus designed for using this method comprises an operable die set 60, tube end thrust unit, opening expansion unit, roll-press unit and press unit. The welding process is eliminated, product quality is improved and the production cost and the investment for the apparatus are reduced by producing this rear axle housing of the vehicle
United States Patent 7681426 discloses a method for manufacturing a one piece axle tube housing with an integral spindle includes providing a tube blank, providing the blank with a region of increased thickness, inserting a mandrel having a reduced diameter profile, passing a reducing die over the tube to conform the tube to the shape of the mandrel; and extraction of the mandrel from the tube to cause outward deformation of the tube at specific locations. A further swaging step may be used to form the final spindle structure.

United States Patent 3726154 discloses arrangement for preventing relative rotation between a differential gear housing and an axle housing tube in a motor vehicle rear axle assembly. The differential gear housing, which may be made of cast non-weldable material, is provided with a sleeve-like portion in the direction of the axle, surrounding and supporting one end of the axle housing tube. According to the invention, the *sieeve-like portion has an opening therein extending substantially radially inward. A pin-like device is arranged in the opening in contact with the sides thereof and is welded to the axle housing tube. This device thereby attaches the axle housing tube to the differential gear housing without the necessity of forming a weld with the differential gear housing
Japanese Patent JP2003191707 discloses invention related to' reduce the number of parts required for a rear axle housing of a commercial vehicle and to secure compatibilty of a slide seat. In a trunnion-suspension type rear 2-axle vehicle, a slide seat of a rear axle housing and a side thrust bracket are integrally cast, and the integrally cast article extends over an upper face of a rear axle housing arm part, a lower face of the integrally cast article whose upper face is stepped over abuts substantially with the whole surface of the upper face, and a flange of the integrally cast article and a shelf part of the rear axle housing arm part are fastened with a shim between them by a bolt.
Japanese Patent JP59024543 discloses invention related to increase fatigue strength of a rear axle housing by removing unevenness due to mold deviation, burrs, traces of welding correction, traces of grinding etc. caused in manufacturing a rear axle housing made of cast steel by blasting work. After casting a rear axle housing as a cast steel product M, the gate is ground by a grinder or acute angled part is ground by welding correction. Then, blasting work by shot peening is performed on the whole body of the rear axle housing. Shot peening is performed by blasting about 0.3W4mm steel shots at blasting speed of 10W50m/sec. Compressive stress is caused on the surface of the rear axle housing by spot peening and internal tensile stress is cancelled by this and concentration of stress is prevented. Consequently, fatigue strength is increased.

Japanese Patent JP57009586 discloses invention related to prevent formation of penetration bead or reinforcement of welding in the part of end case insertion and overlapped part with a cover or a ring by changing the welding condition from other parts and omit subsequent cutting operations, in longitudinal joint welding of a rear axle housing using gaseous carbon dioxide. A torch is shifted in the direction of arrow from the right end of the body of a rear axle housing. When it comes to the starting point of welding, a dog tapsihe first limit switch and a welding start signal is issued. Then, a part out of longitudinal weld zone of butted part of the upper part and lower part of the main part is welded. When the torch comes to a point at the end of the part where a case end is inserted, the dog taps the second limit switch to issue a signal to change the welding condition, and welding is continued changing, for instance, welding current. When the torch comes to the starting point of overlapped part of the body and a ringor a cover, the welding condition is changed similarly. Further, crater processing is made at the terminal of welding to complete longitudinal joint welding.
United States Patent 3583188 discloses the method for making the housing for rear axles of automobiles wherein a tubular steel member is first reduced in its diameter throughout its length with the exception of the middle part to the required diameter of the desired axle housing for carrying the rear axle of a vehicle. Next a tubular member is subjected to a bulging stress to reduce the wall thickness at the middle part of the tubular member. The internal stress is maintained by hydraulic pressure inside the tubular member which precisely shapes the enlarged area and prevents the formation of wrinkles in the shaped material. Lastly, the tubular member is shaped by pressing it from outside while maintaining the pressure inside. The final shaping is affected by means of a die suitable to give the final shape as desired for a rear axle. A rear axle housing is provided having a reduced wall thickness toward the bulged center of the housing from the opposite ends thereof so that the section modulus is substantially uniform from end to end of the housing.
United States Patent 3793703 discloses a rear axle housing comprises two longitudinal sections welded together, each section being produced by the process of first preshaping a rough billet into the general configuration of a forging

blank, forging the blank in several steps into a flat shaped member and then forging the member into the general shape of the housing section. A minimum amount of machining is required to remove the excess material and finish the housing. A special apparatus is provided for performing the intermediate steps of forging the preformed billet into a shaped forging blank.
Japanese Patent JP06190444 provides an automatic bend correcting method for a rear axle housing assembly by which bend is mechanically corrected without skillfulness and highly precisely. In the automatic bend correcting method for the rear axle housing assembly in which tubes are welded to both ends of the housing main body, the assembly is rotated by holding the both ends, the outside deflection of welded part of the tube is measured by a laser sensor and the measured data are inputted in a personal computer which is a controlling device: The position of a press at the time of correcting, the rotating position of the assembly and applied pressure are calculated by the computer based on the data and the bend is corrected by pressurizing the assembly based on a command from the computer.
The critical review of the prior art reveals following technology gaps such as lack of design and layout modification at the blank stage of manufacturing rear axle housing wherein the blank profile is modified so as to enhance material utilisation thereby yield and reduce material wastage without compromising on the housing fatigue, static and specific strength.
To make the most optimal use of available raw materials and to reduce manufacturing costs, there is a continual effort in industry to enhance the yield in rear axle housing manufacturing process. The present invention addresses cost effective solutions to such unmet needs by providing ingeniously designing blank profiles so as to enhance yield from a parent sheet from which the blanks are cut and further manufacturing split housings without compromising on fatigue, static and specific strength.

Objects of the Invention
The main object of the invention is to provide rear axle housing with effective material utilisation. Further object of the invention is to provide method of manufacturing the same.
Yet another object of the invention is to provide blank profile so as to enhance utilisation of material from the metal plate from which blanks are cut.
Yet another object of the invention is to provide blank layout in the said plate.
Yet another object of the invention is to provide method of producing individual -" blanks from the said plate.
Yet another object of the invention is to segregate profiled parts / contoured portion of the blank during producing blanks from the said sheet plate and join the same after forming process in the housing separately.
Yet another object of the invention is to provide joining process of the said portions in the housing.
Thus in accordance with the invention the rear axle housing comprises of:
two formed channels joined with each other in a manner to provide central portion
/ cavity for differential housing
wherein
contoured / profiled portions are joined in the proximity of the said central portion /
cavity
wherein
the process of manufacture of the housing comprises of
segregating contoured / profiled portion of blank;
laying out the said blank formations on parent pfate so as to effectively
utilize entire plate and reduce material wastage;
cutting out the blank formations from the parent plate;

cutting out the said contoured / profiled portions of the blank from the left
out material of the said plate
forming the said blanks to form channels;
joining the two channels to manufacture the housing;
joining the said contoured / profiled portions in the said housing. wherein
the said blank contoured / profiled portions are segregated from the said blank design /formation in a manner to effectively utilise the parent plate area to reduce material wastage wherein
the said contoured / profiled portions are joined such that the fatigue strength of the axle housing is not compromised,
Description of the Invention
Features and advantages of the invention will become apparent in the following detailed description and the preferred embodiments with reference to the accompanying drawings.
Figure 1 Axle Housing assembly with contoured / profiled portions (Sheet 1)
Figure 2 Blank Configurations (Sheet 2)
Figure 3(a) Blank layout on plate (Sheet 3)
Figure 3(b) Blank layout on plate (Sheet 4)
Figure 4 Embodiment of the contoured / profiled portions (Sheets 5 to 8)
Figure 5 Embodiment of the contoured / profiled portions (Sheet 9)
Figure 6 Embodiment of the contoured / profiled portions (Sheet 10)
Figure 7 Embodiment of the contoured /profiled portions (Sheet 11)
Schematic of the rear axle housing is depicted in Figure 1, It comprises of formed channels 1 and 2 joined with each other. The said channels are formed from blank (elaborated in Figure 2). The central cavity 3 is provided for housing differential. As illustrated in the Figure 1, plurality of the contoured profiled triangular like portions 40 are joined between the said two channels 1 and 2 in the

vicinity of the said cavity 3. Figure 1 (b) indicates exploded view of the said portion 40. A cover in the form of a flat ring 5 is provided on the said cavity.
Figure 2 (a) illustrates blank configuration 20 with plurality of contoured / profiled portion 22. In one of the embodiments, these are near triangular in nature. Improved blank configuration 21 is illustrated in Figure 2 (b). It can be seen that the said contoured profiled portions 22 are segregated from the blank in this improved configuration.
Figure 3 (a) provides blank layout indicated on the plate 30. It is evident that by virtue of the said contoured / profiled portions 22 there is substantial wastage of material in terms of area portions 31 and 32 left between consecutive blanks after cutting the blank 20. Figure 3 (b) illustrates improvement layout in the plate 30 (of the same size) wherein the said portions 22 are segregated so as to have the blank configuration 21. The said portions are cut out of the left out area / of the plate in the form of triangular like contoured profiled portion 40. It can be seen that due to improved configuration of the blank 21 in terms of segregating portions 22 and layout to this effect saves substantial portion (in the form of a strip) of the plate 30 as indicated by numeral 41. Thus it is evident that the plate of reduced size can be obtained for the same number of the blanks leading to substantial saving in the raw material. Further since the segregated profiled portions 22 are cut in the form of 40 from the left out material of the plate which otherwise would be wasted saves substantial raw material. The portion 40 is of geometry so as to be adapted to fit in the said two channels 1 & 2.
The blank layout illustrated in Figure 3 (b) is one of the preferred embodiments of the layout. It is to be appreciated that depending on the shape of 40, the layout of the blank has to be appropriately adjusted.
Figure 4 depicts embodiments of the form 40. Variants are depicted in Figure 4 (a) to Figure 40). Each of the variant is illustrated with two views.
The two views of one of the preferred variants of the said form 40 are depicted in Figure 4 (a). It may be noted that there is resemblance between the contoured/

profiled portion 22 of the blank. The portion 40 is configured / resembles with the portion that would have been formed out of the said blank if the portion 22 was retained. The sides 51 and 52 of triangular like form 40 depicted in the Figures 4 (a) are curved inwardly. The base 53 comprises of inwardly contoured profile 54 towards apex side. The other variant of the form 40 is depicted in Figure 4 (b). The said form comprises of sides 55 and 56 curved inwardly. The base 58 comprises of inwardly contoured profile 59 towards apex side. The corners 57 and 60 are rounded as depicted in the Figures 4 (b).
In an embodiment of 40 illustrated in Figure 4(c) depicts the triangular like lamina with a groove 740 with radius, one side stoving angle provided for joining purpose. In another embodiment of 40 illustrated in Figure 4 (d) shows the groove 750 without radius. In yet another embodiment of its half geometry which can be secured to top channel & another similar half geometry to bottom channel. Figures 4 (f) depict triangular like configuration of the said form 40 wherein the base 800 of the triangle is substantially straight Figure 4(f). In other variant depicted in Figure 4(g) the base 900 is curved outside away from apex of the triangle. The variant depicted in Figure 4 (h) is a substantially circular lamina provided with a substantially triangular contoured groove / cut 910. Figure 4 (i) depict substantially rectangular lamina provided with substantially triangular contoured groove / cut 920. Figure 4 (j) depict a polygonal lamina provided with a substantially triangular contoured groove / cut 930. It should not anyway be construed that the specific profile of the blank and / or the said portion 40 restricts the scope of the invention.
Another embodiment of the blank layout of the said plate 30 is illustrated in Figure 5. In this layout the cluster of said profiled portions of the blank 22 are disposed in one section and the said of triangular like contoured profiled portion 40 are segregated on width wise other section of the blank 22 as depicted in the Figure 5(a). The geometry of the said portion 40 used for this layout is depicted in the Figure 5(b). The triangular like surface of the portion 40 comprises of substantially straight sides 501 and 502. The entire base 503 of this triangular like portion is in curved inwardly towards apex as depicted in the Figure 5(b).

Yet another embodiment of the blank layout of the said plate 30 is illustrated in Figure 6. In this layout the cluster of said profiled portions of the blank 22 are disposed in one section and the said of triangular like contoured profiled portion 40 are segregated on width wise other section of the blank 22 as depicted in the Figure 6(a). The geometry of the said portion 40 used for this layout is depicted in the Figure 6(b). The triangular like surface of the portion 40 comprises of substantially straight sides 601 and 602. The entire base'603 of this triangular like portion is greater in length than each of the said sides 601 and 602. Further the base 603 is curved inwardly towards apex as depicted in the Figure 6(b).
Yet another embodiment of the blank layout of the said plate 30 is illustrated in Figure 7. In this layout cluster of said profiled portions of the blank 22 are disposed in one section and the said of triangular like contoured profiled portion 40 are segregated on width wise other section of the blank 22 as depicted in the Figure 7(a). The geometry of the said portion 40 used for this layout is depicted in the Figure 7(b). The triangular like surface of the portion 40 comprises of substantially flat top portion 704 towards the base 703. The said flat portion 704 further extends as slanted portion 705 towards the apex of the triangular portion. The base 703 of the triangular portion is curved inwardly towards apex as depicted in Figure 7(b).
In one of the embodiment the said portion 40 is secured to the said channels 1 & 2 of the housing by welding. In another variant of this embodiment the portion 40 is bolted with the housing. In yet another variant the said portion 40 is affixed to the housing.
The raw material of the plate is selected from any metal / alloy based on the load, operating conditions that are defined by the end application. For example if the raw material is steel, the Yield strength is in the range of 200 to 550 MPa. In another option if the raw material is selected from Aluminium alloy, the Yield Stress is in the range of 100 to 400 MPa.
Using the shape 40 illustrated in figure 4 (a) together with blank layout given in figure 3(b), results in saving of 10-15% in raw material consumption.

To substantiate the aspect of strength wherein the said portion 40 does not adversely affect specific strength, first detailed static strength analysis is carried out followed by experimental validation. The stress distribution for the integrated channel (without the said portion 40) and the invented design (with the said portion 40) is carried out using Finite Element Analysis. The analysis of the critical region was carried out based on Von Mises - Hencky criterion for ductile failure. The said region is assumed to be subjected to the acute load conditions resulting in development of stresses acting in different directions wherein the magnitude and direction of these stresses vary at each of the discrete point in the said region. The Von Mises index (or number) is calculated to provide equivalent stress combining (principal) stresses in x, y and z direction at a particular discrete location.
The vertical load value acting on the rear axle is considered as 11 ton as representation for both the cases. The objective of this analysis is to quantify stress distribution in the proximity wherein the said portion is attached / welded / secured to the channels 1 &2 and further compare the stress value with the maximum stress in the channels. The results of the analysis are depicted in Table 1.
Table 1: Finite Element Analysis results for a conventional integrated channel design & the invented design

in
Rear axle housing De'siiin' l STRESS IMPal Deflection [him]

Channel region Max stress Channel region stress, near to said portion 40 Stress at saici; portion 40

Integrated channel 246 151 - 3.3
Invented design 245 152 133 3.3
As illustrated in the Table 1, the stress value in the vicinity of the said portion 40 is of the order of 133 MPa wherein the maximum stress in the channel is 245 MPa.
To experimentally validate the abovementioned analysis, four test samples of automotive rear axle housing were manufactured in accordance with the present

invention with effective utilisation of raw material. The contoured profiled portion (22) was segregated from the blank and was cut separately from the parent plate in the form of a triangular like portion (40) that was then welded to the said channels (1 &2) of the housing. The said rear axles were tested for fatigue at 2G loading conditions.
The test samples sustained the Test Boogie of 500,000 cycles in vertical bending fatigue without failure. It is concluded based on the analysis and experimental validation that by securing the said portion (40) the maximum stress value is not affected. The deflection value is also not affected due to the said portion. The rear axle housing sustains the Test Bogie for 500,000 cycles without failure. Thus the welding of the said triangular like portion (40) does not adversely affect strength of the axle. The segregation of the contoured profiled portion (22) from the blank and disposing it in the form of the triangular like portion (40) on the parent plate results in substantial saving of the order of 12% in raw material.
Further the stress value in the region is of the order of 133 MPa that is substantially lower than the maximum stress value. Therefore
Thus it is evident that the synergistic combination of the blank configuration by virtue of segregating contoured / profiled, separately cutting the same from the parent plate from the left out material after cutting the blanks and further joining the said portions with the formed housing results in substantial saving in the raw material in terms of selecting substantially smaller size plate without compromising on the fatigue, static, specific strength and performance of the rear axle housing.

We Claim
1. Automotive rear axle housing comprising
formed channels (1 and 2) joined with each other; central cavity (3)
provided for housing differential; plurality of the contoured portions (40)
that are joined between the said two channels (1 and 2) in the vicinity of the
said cavity (3); a cover in the form of a flat ring (5) provided on the said
cavity
wherein the channels are formed from blank.
2. Automotive rear axle housing as claimed in claim 1 comprising
two formed channels (1 and 2) joined with each other in a manner to
provide central cavity (3) for differential housing
wherein
contoured profiled portions (40) are joined in the proximity of the said
centra] cavity (3)
wherein
the process of manufacture of the housing comprises of
segregating contoured profiled portion of the blank;
laying out the said blank formations on parent plate so as to
effectively utiiize entire plate and reduce material wastage;
cutting out the blank formations from the parent plate;
cutting out the said contoured / profiled portions of the blank from
the left out material of the said plate;
forming the said blanks to form channels;
joining the two channels to manufacture the housing;
joining the said contoured profiled portions in the said housing wherein
the said blank contoured profiled portions are segregated from the said blank to effectively utilise the parent plate area to reduce material wastage.
3. Automotive rear axle housing as claimed in claim 1 wherein the contoured
profiled portions (22) are segregated from the blank.

4. Automotive rear axle housing as claimed in claims 1, 3 wherein the said contoured profiled portions (22) are cut out of the left out area / of the plate in the form of triangular like portion (40) so as to save substantial portion of the plate from which the blanks are cut.
5. Automotive rear axle housing wherein the said parent plate comprises of
■J -.
laid out blank formations wherein contoured profiled portions (22) are segregated from the blank wherein
the said contoured profiled portions (22) in the form of triangular like portion (40) are disposed in between adjacent blanks on the said parent plate (Figure 3b).
6. Automotive rear axle housing as claimed in claims 1-5 wherein the said
parent plate comprises of laid out blank formations wherein contoured
profiled portions (22) are segregated from the blank wherein
the said contoured profiled portions (22) in the form of triangular like portion (40) are disposed on the said parent plate in the leftover space.
7. Automotive rear axle housing as claimed in claims 1, 4-6 wherein the said triangular like portion (40) is provided with a stoving angle (40).
8. Automotive rear axle housing is provided with as claimed in claims 1, 4-7 wherein the said triangular like portion (40) comprises of a groove without radius.
9. Automotive rear axle housing is provided with as claimed in claim 1 the said triangular like portion (40) is secured with the said channels (1 & 2) of the housing by welding.
10. Automotive rear axle housing is provided with as claimed in claim 9 wherein the said triangular like portion (40) is bolted to the said channels (1&2) of the housing.

11. Automotive rear axle housing is provided with as claimed in claim 10 wherein the said triangular like portion (40) is affixed to the said channels (1&2) of the housing.
12. Automotive rear axle housing is provided with as claimed in claims 1-11 wherein the said portion (40) is a profiled portion.
13. Automotive rear axle housing is provided with as claimed in claims 1-12 wherein the raw material of the plate is selected from metal, alloy, non-metal based on the load, operating conditions that are defined by the end application
14. Automotive rear axle housing is provided with as claimed in claims'1- 13 wherein the blank layout (Figure 5(a)) of the said plate (30) comprises of cluster of said profiled portions of the blank (22) disposed in one section and the said of triangular like contoured profiled portion (40) segregated on width wise other section of the blank (22) (Figure 5(a))
wherein the triangular like surface of the portion (40) comprises of substantially straight sides (501) and (502) , the entire base (503) of this triangular like portion is in curved inwardly towards apex (Figure 5(b)).
15. Automotive rear axle housing is provided with as claimed in claims 1-14
wherein the blank layout (Figure 6(a)) of the said plate (30) comprises of
cluster of said profiled portions of the blank (22) disposed in one section
and the said of triangular like contoured profiled portion (40) segregated on
width wise other section of the blank (22)
wherein the triangular like surface of the portion (40) comprises of substantially straight sides (601) and (602), The entire base (603) of this triangular like portion is greater in length than each of the said sides (601) and (602), the base (603) is curved inwardly towards apex (Figure 6(b)).

16. Automotive rear axle housing is provided with as claimed in claims 1- 15 wherein the blank layout (Figure 7(a)) of the said plate (30) comprises of cluster of said profiled portions of the blank (22) disposed in one section and the said of triangular like contoured profiled portion (40) segregated on width wise other section of the blank (22)
wherein the triangular like surface of the portion (40) comprises of substantially flat top portion (704) towards the base (703), the said flat portion (704) further extends as slanted portion (705) towards the apex of the triangular portion, the base (703) of the triangular portion is curved inwardly towards apex.