WO2018033936A2

WO2018033936A2 - Rigid lightweight front axle beam and manufacturingthereof

Info

Publication number: WO2018033936A2
Application number: PCT/IN2017/050345
Authority: WO
Inventors: Babasaheb KALYANI; Sumedh KOUSADIKAR; Mangesh YADAV; Dattaprasad LOMATE; Sourabh SINDAGI; Manoj UKHANDE; Vijaykumar KHASNIS; Madan TAKALE; Rajkumar SINGH
Original assignee: Bharat Forge Ltd
Current assignee: Bharat Forge Ltd
Priority date: 2016-08-13
Filing date: 2017-08-13
Publication date: 2018-02-22
Anticipated expiration: 2019-02-13
Also published as: WO2018033936A3

Abstract

The present invention relates to a light weight axle beam having strengthening rib arrangement at a region of the axle beam where stress due to torsional forces or fatigue loading attains maximum value during the operation of the axle beam. The arrangement of at least one stiffening rib provides stiffness to beam to withstand torsional and bending loads; and improved deflection characteristics.

Description

RIGID LIGHTWEIGHT FRONT AXLE BEAM AND

MANUFACTURINGTHEREOF

Field of the Invention:

[0001] The present invention relates to automotive components and particularly, but not exclusively relates to axle beam of a vehicle.

Background and Introduction:

[0002] In recent years, improving fuel economy to reduce carbon footprint has emerged as an important aspect in the automotive industry. Consequently, complex manufacturing methods are being developed for light weighting of front axle beams used in commercial vehicles and heavy duty trucks. The front suspension arrangement in non-independent suspension system which carries large loads consist of a solid front axle beam and wheel assemblies that are connected to the vehicle with shock absorbers and leaf springs which are mounted longitudinally over front axle beam.

[0003] The front axle beam typically experiences following types of loading conditions:

1. Vertical reaction bending force from the vehicle surface.

2. Dynamic braking reaction force due to brake application.

3. Dynamic cornering force due to turning of vehicle. [0004] Combination of above forces exerts torsional force to the critical area of the front axle beam, e.g. goose neck, king pin boss and the like. As front axle beam is made from variety of sections mostly by combination of I, T, and rectangular sections etc., the front axle beam can be made lightweight by slimming these sections. However, this increases deflection under above-load cases results in reduced stiffness.

[0005] Strengthening the beam section is possible by increasing area of cross sections; however, such arrangement causes utilization of additional material which, in-turn, increases weight of the beam.

[0006] Accordingly, in spite of the available front axle beams, there remains a very real and substantial need for manufacturing lightweight front axle beam using a forging process which improves strength and deflection characteristics.

Object of the Invention:

[0007] It is an object of the present invention to provide a forged front axle beam having light weight structure.

[0008] It is another the object of the present invention to provide an arrangement in the front axle beam which not only reduce the weight of beam but also provides stiffness/strength to withstand torsional and bending loads. [0009] It is a further object of the present invention to provide a forging method of manufacturing a lightweight front axle beam which requires less material but provides improved strength with reduced deflection.

[0010] These and other objects, features and advantages, will be readily apparent upon consideration of the following detailed description of the invention in conjunction with the accompanying drawings.

Brief Description of Figures:

[0011] Figure 1 shows an end portion of the lightweight front axle beam in accordance with one embodiment of the present invention.

Detailed Description of the Invention:

[0012] The present invention is focused on manufacturing a light weight front axle beam, particularly on improving deflection characteristics of light weight front axle beam under vertical bending and torsional loads.

[0013] The present invention relates to a light weight front axle beam having strengthening rib arrangement at a region of the axle beam where stress due to torsional forces or fatigue loading attains maximum value during the operation of the axle beam. [0014] In one of the embodiments of present invention, to overcome the torsional stiffness due to twisting action and bending effect due to vertical reactions, the I section, the T section of the front axle beams are made rigid by dimensional parameter optimization in such a way that, the weight of the beam is substantially reduced with improved deflection characteristics of the beam than the existing beam design. In accordance with first aspect of the present invention, there is provided a light weight front axle beam comprising at least one stiffening rib, preferably a pair of stiffening means.

The inventors, after several trials and experiments, arrived at a particular shape of stiffening rib in order to provide desired stiffness characteristics.

[0015] In one embodiment said stiffening means has "Z/S" type or "Z/S" shaped configuration. In one exemplary embodiment of the present invention, the front axle beam (100) comprises a pair of pad sections (10); a pair of arm- sections (12); and a pair of king pin boss (14), characterized in that said arm section comprises a pair of stiffening ribs having "Z/S" type configuration (16). The stiffening ribs are integral part of said axle beam which is extending between the space of top and bottom faces of said arm section. Said stiffening rib is adapted to provide stiffness to front axle beam to withstand torsional and bending loads; and improved deflection characteristics. [0016] An exemplary implementation of the axle beam would now be explained with respect to Fig. 1.

[0017] Fig. 1 illustrates one of the end portions of the axle beam 100, in accordance with one implementation of the present invention. The axle beam 100 may include a pad section 10 that forms maximum length of the axle beam 100. The pad section 10 may be understood as a long beam section having I or T shaped section. Further, the pad section 10 forms as a main load bearing section of the vehicle's weight. In addition, the pad section 10 also provides a platform to couple various components of the suspension system to the vehicle. The axle beam 100 also includes an arm section 12 extending from the pad section 10. The arm section 12 may be understood as a hitch profile of the axle beam 100. Further, the axle beam 100 has a contoured profile. As shown in Fig. 1, the arm section 12 may have a profile of letter 'Z/S'. As may be understood, the axle beam 100 has similar arm section and pad section (not shown in fig.) on the other end of the axle beam 100. The purpose of the arm section 12 is to provide an elevated position to mount various components so as to provide adequate ground clearance. Additional constructional details of the arm section 12 would be explained in subsequent embodiments.

[0018] The axle beam 100 may also include a kingpin boss 14 extending from one end of the arm section 12. In an example, the kingpin boss 14 is used to mount components, such as a stub axle assembly. In an example, the kingpin boss 14 may have a cylindrical through hole that may receive a key or a kingpin. The manner by which the components are mounted on the kingpin boss 14 is known in art and hence will not be discussed.

[0019] Referring back to Fig. 1, the arm section 12 may further include strengthening rib arrangements 16 on both sides of the arm section 12. The purpose of the rib arrangement 16 is to provide a predetermined strength to the axle beam at the arm section 12, while at the same time, reducing the material needed to attain the predetermined strength. The rib arrangement 16 may form an integral part of the arm section 12 i.e. the rib arrangement 16 is formed during forging of the axle beam 100. The ribs 16-1 and 16-2 are contoured, advantageously, to map the interior profile of the arm section 12 of the axle beam 100.

[0020] In the illustrated implantation, the rib arrangement is of a pre-defined shape comprising a locus of points divided in at least three parts. A first portion of the rib arrangement is defined as a first locus of points which is collinear to each other at incrementally varying heights from an operative horizontal surface. In other words, this first locus of points defines a vertical member. A second subsequent portion of the rib arrangement is defined as a second locus of points which is collinear to each other at same heights form an operative horizontal surface. In other words, this second locus of points defined a horizontal member, having a first end and a second end, wherein the first end extends from the bottom part of the first vertical member. A third subsequent portion of the rib arrangement is defined as a third locus of points which is collinear to each other at incrementally varying heights from an operative horizontal surface. The first locus of points is offset from the third locus of points by the second locus of points. In other words, the third locus defines a vertical member which starts from the second end of the horizontal member and extends operatively member. In effect, the first locus of points, the second locus of points, and third locus of points form a shape that substantially bears a Z/S shaped profile or configuration. Such an arrangement may be provided on both the sides of the arm section 12. Further, the Z/S shaped configuration provides additional stiffness to the axle beam 100.

[0021] In one example, the inclusion of "Z/S" type stiffening rib arrangement 16 in the predetermined location reduce the deflection of lightweight front axle beam by 10 to 15% under combination of vertical and braking load cases. Moreover, the "Z/S" type rib arrangements 16 prevents stress development under application of prescribed loads.

[0022] The axle beam 100 with the aforementioned rib arrangement 16 may be formed by various methods, such as closed die forging. Generally, in the closed die forging, a set of blocker and finisher may be employed to form the axle beam 100. The blocker and the finisher may be understood as metal block that has a cavity whose inner surface corresponds to the outer surface of the axle beam 100 to be formed. In order to form the axle beam 100 with the rib arrangement 16, the blocker and the finisher is prepared by carving out the depression in the inner cavity that corresponds to the rib arrangements 16. In an example, the axle beam 100 thus manufactured by close die forging is treated to ensure that there were no forging defects in the axle beam 100.

[0023] In accordance with another aspect of the present invention there is provided a method of manufacturing said light weight front axle beam by using closed die forging process.

[0024] In above said steps of forging, in the set of blocker and finisher dies, an impression of "Z/S" type stiffening rib is engraved using machining operation. The forge-ability of said engraved dies is verified using 3D metal flow simulation and during forging operation, it is ensured that no forging defects have been observed.

Advantages of the invention:

[0025] The inclusion of "Z/S" type stiffening rib in the critical location reduce the deflection of lightweight front axle beam by 10 to 15% under combination of vertical and braking load cases. The weight of front axle beam of the present invention found to be at least 10 to 15% less than the conventional front axle beam.

[0026] The afore-mentioned advantages are achieved post various design optimizations. To arrive at the present front axle beam design with reduced weight and reduced deflection, more than 45 front axle beams were designed as trial axle beams. In one of the trial designs the stiffening means employed was "horizontal ridge" or "I shaped stiffener" between the space of top and bottom faces of said arm section. The deflection was found to reduce by 2.7 to 8.7 %. However, there was weight gain of 0.4 to 1 %. In another trial design, the stiffening means employed was a combination of two parallel vertical ridges between the space of top and bottom faces of said arm section. The deflection was found to reduce by 8.2 to 8.7, however, there was weight gain of about 1.2 %.

[0027] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. [0028] The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

[0029] Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

[0030] The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

[0031] While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

Claims:

1. A rigid light weight axle beam comprising at least one stiffening means at a region of the axle beam where stress due to torsional forces or fatigue loading attains maximum value during the operation of the axle beam, said stiffening means exhibit a pre-defined shape comprising a locus of points divided in at least three parts, characterized in that, a first portion of said stiffening means is defined as a first locus of points which is collinear to each other at incrementally varying heights from an operative horizontal surface, a second subsequent portion of said stiffening means is defined as a second locus of points which is collinear to each other at same heights form an operative horizontal surface, having a first end and a second end, a third subsequent portion of said stiffening means is defined as a third locus of points which is collinear to each other at incrementally varying heights from an operative horizontal surface, said first locus of points being offset from said third locus of points by said second locus of points. .

2. The axle beam as claimed in claim 1, wherein said first locus of points, said second locus of points, and said third locus of points form a shape that substantially bears a"Z/S" type or "Z/S" shaped configuration for said stiffening means.

3. The axle beam as claimed in claim 1, wherein said front axle beam (100) comprises a pair of pad sections (10); a pair of arm- sections (12); and a pair of king pin boss (14), characterized in that said arm section comprises a pair of stiffening means having "Z/S" type configuration (16), said stiffening means adapted to provide a predetermined strength to the axle beam at the arm section 12, while at the same time, reducing the material needed to attain the predetermined strength.

4. The axle beam as claimed in claim 1, wherein the stiffening means are integral part of said axle beam which is extending between the space of top and bottom faces of said arm section, said stiffening means being adapted to provide stiffness to beam to withstand torsional and bending loads; and improved deflection characteristics.

5. The axle beam as claimed in claim 1, wherein the pad section 10 is I or T shaped region which bears main load of the vehicle's weight and forms maximum length of the axle beam 100, said pad section 10 adapted to provide a platform to couple component/s of the suspension system to the vehicle.

6. The axle beam as claimed in claim 2, wherein the arm section 12 which is extending from the pad section 10 is a hitch profile of the axle beam 100 having profile of letter 'Z/S'.

7. The axle beam as claimed in claim 2, wherein the kingpin boss 14 is extending from one end of the arm section 12 and used to mount a stub axle assembly, said kingpin boss 14 has a cylindrical through hole that receive a key or a kingpin.

8. The axle beam as claimed in claim 2, wherein stiffener means 16 form as an integral part of the arm section 12 which is formed during forging of the axle beam 100, said stiffener means has Z/S shaped configuration which provides additional stiffness to the axle beam 100.

9. The axle beam as claimed in claims 1 to 8, characterized in that, said lightweight front axle beam exhibit reduced deflection by at least 10 to 15% and reduced weight by at least 10 to 15%.

10. A method for manufacturing a rigid light weight axle beam (100) as claimed in claims 1 to 8; said method comprises close die forging of a metal block to form the axle beam with integral stiffening means.