WO2024038411A1

WO2024038411A1 - An axle and method of manufacturing thereof

Info

Publication number: WO2024038411A1
Application number: PCT/IB2023/058274
Authority: WO
Inventors: Babasaheb Neelkanth Kalyani; Basavraj Prabhakar KALYANI; Madan Umakant TAKALE; Kedar PARANJAPE; Manoj UKHANDE; Kailash SANGSHETTI
Original assignee: Bharat Forge Limited
Priority date: 2022-08-18
Filing date: 2023-08-18
Publication date: 2024-02-22

Abstract

The present disclosure relates to an axle (200). The axle includes a beam (202), a LH spindle (204), and a RH spindle (206). The beam (202) has a first end (208) and a second end (210). In addition, the LH spindle (204) is integrally formed at the first end (208). Further, the RH spindle (206) is integrally formed at the second end (210). Furthermore, the axle (200) is manufactured using a closed die hot forging process.

Description

TITLE OF THE INVENTION:

AN AXLE AND METHOD OF MANUFACTURING THEREOF

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY

The present application claims priority from Indian patent application no. 202221046898 filed on the 18^th day of August 2022, the details of which are incorporated herein by a reference.

FIELD OF THE INVENTION

The present invention relates to an axle. More particularly, the present invention relates to the axle used in a vehicle and a method of manufacturing thereof.

BACKGROUND OF THE INVENTION

The rear axle is a critical component of a vehicle. Traditionally, the rear axle consists of a beam and a pair of spindles attached to each end of the beam. The beam and the pair of spindles are coaxial. In some of the traditional scenario, the beam is hollow with hollow bulge at the center for mounting a differential at the center. However, the conventional method involves manufacturing the pair of spindles and the beam separately and then assembling them using bolts. The use of bolted joints in the rear axle assembly poses potential risks, as these components are constantly subjected to dynamic loading. The bolts may become loose during vehicle operation, which can lead to sudden breakage and failure. Moreover, the process of assembling the spindles with the rear axle beam is an additional task that requires time and resources.

Therefore, it is necessary to either change the method of joining the spindles to the rear axle or integrate the spindles with the beam to enhance the strength of the rear axle. However, integrating the spindles with the conventional rear axle beam presents significant challenges. It involves designing a complex shape for the integrated rear axle beam and making modifications to the forging process.

The casting method is commonly used to produce intricate-shaped components, but it has disadvantages such as the absence of favorable microstructural phases and grain flow structure across the component's contour. This can result in fatigue failure when the component is subjected to dynamic and cyclic loading. These drawbacks can be overcome by using a hot forging method, which can provide the desired microstructural phases and grain flow across the component's contour, thereby improving fatigue resistance to dynamic and cyclic loading on the axles. However, forging an integral rear axle is a complex task compared to the existing three-piece design (the beam and the pair of spindles). The forge master faces several challenges in the forging process. For example, the integrated beam has different horizontal and vertical planes, the position of the spindles is located away from the central portion of the rear axle beam, and there are cavities inside the spindles.

Thus, problems identified include but are not limited to: i. Three-piece assembly (the beam and the pair of spindles) of the rear axle reduces its strength and reliability. ii. The manufacturing of the integrated rear axle (the beam and the pair of spindles as a one- piece) using the casting results in non-uniform grain flow which is non suitable for cyclic loading. iii. Traditionally, the pair of spindles and the beam are coaxial which consumes additional space. iv. Traditionally, the hollow beam is used which non suitable for supporting other additional components. v. The design of the traditional rear axle is poor and is not aesthetically appealing.

Thus, there is a need for a rear axle in which the beam and the pair of spindles are one-piece and said rear axle is formed using the forging process for withstanding the dynamic and cyclic loading.

SUMMARY OF THE INVENTION

This summary is provided to introduce concepts related to a rear axle and method of manufacturing the rear axle. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

In one non limiting embodiment of the present subject matter an axle for vehicle is disclosed. The axle comprises a beam having a first end and a second end, a LH spindle, and a RH spindle. Further, the LH spindle integrally formed at the first end. The RH spindle integrally formed at the second end. The beam is solid beam. Further, the first end and the second end of the beam includes hollow hemispherical cavities. Further, the LH spindle and the RH spindle are hollow.

In another non limiting embodiment a method for manufacturing an axle is disclosed. The method includes the various steps such as: a. Providing a billet as an input raw material. b. Heating a billet. c. Subjecting the heated billet to rolling to obtain a reduced rolling preform. d. Deforming the reduced rolling preform to produce a bender preform. e. Blocker forging the bender preform to obtain a blocker preform. f. Finish forging the blocker preform to obtain a finish forged axle. g. Trimming the finish forged axle. h. Subjecting the axle to post-forging operations.

BRIEF DESCRIPTION OF DRAWINGS

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

Figure 1 illustrates a conventional rear axle (bolted design);

Figure 2 illustrates an axle, in accordance with an embodiment of the present subject matter; and

Figure 3 illustrates a process for manufacturing the axle, in accordance with an illustrative embodiment of the present subject matter.

DETAILED DESCRIPTION

As used in the specification and claims, the singular forms “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “an article” may include a plurality of articles unless the context clearly dictates otherwise. Those with ordinary skill in the art will appreciate that the elements in the figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention. There may be additional components described in the foregoing application that are not depicted on one of the described drawings. In the event such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification.

In the accompanying drawings components have been represented, showing only specific details that are pertinent for an understanding of the present invention so as not to obscure the disclosure with details that will be readily apparent to those with ordinary skill in the art having the benefit of the description herein.

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the invention.

The present subject matter relates to a rear axle and a method of manufacturing of said rear axle using forging process.

Referring to figure 1 which illustrates a conventional rear axle (bolted design). The conventional rear axle beam assembly (100) may include a beam (102), a pair of spindles (104, 106) and a plurality of bolts (108, 110). The pair of spindles (104, 106) may be assembled to the beam (102) using the plurality of bolts (108, 110). The conventional rear axle may have many disadvantages such as low strength, time required for assembly and less reliability.

Referring to figure 2, an axle in accordance with an embodiment of the present subject matter is illustrated. An axle (200) may include a beam (202), a LH spindle (204), a RH spindle (206). The beam (202) may have a first end (208) and a second end (210). The LH spindle (204) may be integrally formed at the first end (208). The RH spindle (206) may be integrally formed at the second end (210). The axle (200) may be mounted on rear side of a vehicle. In other embodiments, the vehicle may be electric powered vehicle, vehicle may be a commercial vehicle with electric propulsion. Vehicle may represent any type of commercial vehicle, such as a vehicle with an integrated cargo volume, (e.g., a delivery van or a box truck), a flatbed truck, a pickup truck, a truck with an enclosed cargo box, a towing vehicle, and/or any other such commercial vehicle. The vehicle may be an internal combustion (IC) engine powered vehicle.

In an embodiment, the beam (202) may be a solid beam. In another embodiment, the beam (202) may include the seats for mounting leaf springs. In a specific embodiment, the beam (202) may include the two spring seats. The beam (202) may include two spring seats for mounting the overslung leaf springs. In one embodiment, the spring seats may be integrally formed with the axle (200). In another embodiment, the spring seats may be welded to the beam (202). In yet another embodiment, the spring seats may be bolted to the beam (202). A powertrain of the electric powered vehicle may be supported by the axle (200). A differential assembly may be mounted on the axle (200). The LH spindle (204) and the RH spindle (206) may be hollow. The powertrain may include one or more electric motor, a transmission, a differential, and/or other components for the transmission of power to the wheels of the vehicle. The powertrain may be powered by electricity to generate rotational motion, which may then be communicated to the wheels of the vehicle to move the vehicle.

Further, the first end (208) and the second end (210) of the beam (202) may include hollow hemispherical cavities. In the context of vehicles, transmission plays a crucial role in distributing torque efficiently. It can receive torque as input from the IC engine, or electric motor, or combination thereof and amplify this torque before transmitting it to the differential. The differential, in turn, distributes the torque among pair of wheels, typically the left and right wheel/tire assembly, using a pair of half shafts. The pair of half shaft may be passed through the hollow hemispherical cavities of the beam (202), first and RH spindle (204, 206) respectively.

In one embodiment, the beam (202) and the axis of the LH spindle (204) and the RH spindle (206) may be inline. In another embodiment, the beam (202) and the axis of the LH spindle (204) and the RH spindle (206) may be offset. The offset may be in the range of 120 mm to 160 mm. The offset may create additional space at rear side for mounting other components. A pair of rear wheels may be mounted on the LH spindle (204) and the RH spindle (206). The pair of wheels may receive rotational power from the pair of half shafts.

Referring to figure 3, a process for manufacturing the axle (200) in accordance with the embodiment of the present subject matter is illustrated. An axle (200) may include a beam (202), a LH spindle (204), a RH spindle (206). The beam (202) may have a first end (208) and a second end (210). The LH spindle (204) may be integrally formed at the first end (208). The RH spindle (206) may be integrally formed at the second end (210). The axle (200) may be mounted on rear side of a vehicle. Preferably, the beam (202) and a pair of spindles (204, 206) may be non- separable, and the beam (202) and pair of spindles (204, 206) may be forged as a single part or one piece.

In accordance with another aspect of the present invention, there may be provided with a process for manufacturing the axle (200) using a closed die hot forging process. The hot forging process starts from a “rolled” round or rounded comer section (RCS) billet which is then subjected to various forging operations. The forging process for manufacturing the integral design of axle (200) for vehicle according to the present invention m ay include reduce rolling (RR), bend preforming (Bending), blocker forging (BLK), finisher Forging (FIN) and trimming (Post forging operations).

In the manufacturing of the rear axle beam, any type of forging equipment known to person skill in the art such as a mechanical press or screw press or wedge press or hydraulic press or hammer can be used.

The method (300) of manufacturing the axle (200) according to one embodiment of the present invention may include the following steps:

In step (302), a billet may be provided as an input raw material. The billet may be extruded or rolled billet. The cross section of the billet may be cylindrical or rounded cross section (RCS). The material of billet can be preferably a steel alloy.

In step (304), the billet may be heated. In one embodiment, heating of the billet is performed in the range of 1150 to 1250 °C. In another embodiment, heating of the billet is performed to a temperature higher than 1150 °C.

The billet may be heated in an oil fired or gas fired or electric or induction furnace. The heated billet may be transferred to a reduce rolling machine, where reduce rolling operation takes place. During the reduce rolling operation, the cylindrical or RCS billet may be converted into a stepped Reduced Rolled (RR) preform. The output of this process is an RR preform.

In step (306), the heated billet may be subjected to rolling to obtain a reduce rolling preform.

In step (308), the reduce rolling preform may be deformed to produce a bender preform. The preform (RR preform) may be transferred to bender dies. During this operation, the RR preform may be deformed to produce the required bias in the shape of bender preform. The bias may be for producing offset between axis of the beam (202) and the axis of the LH spindle (204) and the RH spindle (206).

In step (310), the bender preform may be subjected to blocker forging to obtain a blocker preform, the bender preform may be transferred to the blocker dies where blocker operation takes place. The blocker forging operation produces rough shape of axle (200) with maximum material flow happening in this stage with some access material thrown out as flash. The output of this stage is the blocker preform.

In step (312), the blocker preform may be subjected to finish forging to obtain a finish forged axle, the blocker preform may be transferred to the finisher dies where the finisher forging operation takes place. In this operation, the final shape of axle (200) may be formed with a small amount of material thrown in the form of flash.

In step (314), the finish forged axle may be trimmed. Further, in step (316), axle (200) may be subjected to post forging operation. The post forging operations which include but are not limited to trimming, padding, wedging, shot blasting, heat treatment, machining and the like are performed. This step produces the final integral rear axle beam.

Technical Advance & Economic Significance

The benefits of the axle (200) include but are not limited to:

1. The need for bolting has been eliminated from the axle (200), resulting in significantly increased strength compared to the conventional bolted design.

2. The axle (200) has been seamlessly integrated using forging process, resulting in superior fatigue strength when compared to axle beams manufactured using other methods.

3. The axle (200) and manufacturing process have successfully reduced both operational and production costs by transforming a three-component design into a single, integrated component design.

Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “consisting of’, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

Claims

WE CLAIM:

1. An axle (200) comprising: a beam (202) having a first end (208) and a second end (210); a LH spindle (204) integrally formed at the first end (208); and a RH spindle (206) integrally formed at the second end (210).

2. The axle (200) as claimed in claim 1, wherein the axle (200) is mounted on rear side of a vehicle,

3. The axle (200) as claimed in claim 1, wherein the beam (202) is solid beam.

4. The axle (200) as claimed in claim 1, wherein an axis of the beam (202) and an axis of the LH spindle (204) and the RH spindle (206) are inline.

5. The axle (200) as claimed in claim 1, wherein the axis of the beam (202) and an axis of the LH spindle (204) and the RH spindle (206) are offset, wherein the offset is in the range of 120 mm to 160 mm.

6. The axle (200) as claimed in claim 1, wherein the first end (208) and the second end (210) of the beam (202) comprises hollow hemispherical cavities.

7. The axle (200) as claimed in claim 1, wherein the LH spindle (204) and the RH spindle (206) are hollow.

8. The axle (200) as claimed in claim 1, wherein a pair of rear wheels are mounted on the LH spindle (204) and the RH spindle (206).

9. The axle (200) as claimed in claim 1, wherein the beam (202) comprises two spring seats for mounting the overslung leaf springs.

10. A method (300) for manufacturing axle (200), wherein the axle (200) comprising a beam (202), a LH spindle (204) and a RH spindle (206), wherein the beam (202) having a first end (208) and a second end (210), wherein the LH spindle (204) integrally formed at the first end (208) and the RH spindle (206) integrally formed at the second end (210), wherein the method (300) comprising the following steps: a. providing a billet (302) as an input raw material; b. heating a billet (304); c. subjecting the heated billet to reduce rolling (306) to obtain a reduced rolling preform; d. deforming the reduced rolling preform (308) to produce a bender preform; e. blocker forging (310) the bender preform to obtain a blocker preform; f. finish forging (312) the blocker preform to obtain a finish forged axle (200); g. trimming (314) the finish forged axle (200); and h. subjecting the axle (200) to post-forging operations (316). The method (300) for manufacturing the axle (200) as claimed in claim 9, wherein the billet provided in step (a) is extruded or rolled billet, wherein the cross section of the billet is cylindrical or rounded cross section (RCS). The method (300) for manufacturing the axle (200) as claimed in claim 9, wherein the heating of the billet in step (b) is performed in the range of 1150 to 1250 °C. The method (300) for manufacturing the axle (200) as claimed in claim 9, wherein the rolling of the billet in step (c) converts the billet into a stepped reduced rolled (RR) preform. The method (300) for manufacturing the axle (200) as claimed in claim 9, wherein the post forging operations of step (h) is selected from the group of processes trimming, padding, wedging, shot blasting, heat treatment, and machining are performed on the axle (200).