Rear cross member for vehicles applied by extrusion and its manufacturing method

Abstract

The present invention relates to an extrusion-applied rear cross member for a vehicle and a method for manufacturing the same. More specifically, the invention relates to a rear cross member for a vehicle in which a pair of side members are symmetrically connected to both sides of a front member and a rear member so as to prevent twisting or bending in the front, rear, or left and right directions of the vehicle, wherein the upper part is connected to the vehicle body and a pair of side members are connected symmetrically to both sides of the front member and the rear member, and the front member and the side member are integrally formed by extrusion; a front body mounting part that is extruded and inserted into each end of the front member and fastened; and a rear body mounting part that is extruded and inserted into each end of the rear member and fastened.

Description

Technology Field

[0001] The present invention relates to a rear cross member for a vehicle with extrusion and a method for manufacturing the same. Background Technology

[0002] Generally, in passenger vehicles, cross members are installed at the front and rear wheel positions along the vehicle's width to support many suspension components and withstand lateral loads transmitted to the vehicle body, by installing them at the points where the suspension load is concentrated. Depending on the installation location, cross members are classified into front cross members and rear cross members.

[0003] The front cross member or rear cross member has its upper part connected to the vehicle body and its lower part connected to the suspension, and functions to prevent twisting or bending of the vehicle in the front, rear, or left and right directions.

[0004] In the rear cross member, an assist arm and a lower arm are connected by an eccentric cam bolt to allow adjustment of the toe angle and camber angle in order to improve the straightness and drivability of the vehicle wheels. By rotating the cam bolt guided by the cam guide, the toe angle and camber angle can be adjusted.

[0005] A representative example is the rear cross member for a vehicle disclosed in Korean Patent Publication No. (A) 10-2020-0132472 (2020.11.25.), which is configured to include: a cam bolt seating portion in which a cam bolt insertion hole portion into which a cam bolt portion is inserted is formed; a base portion connected to the cam bolt seating portion and having a crack prevention hole portion formed therein to prevent cracking; and a pair of cam bolt support portions that protrude outward from the base portion and are positioned on both sides of the cam bolt seating portion to support the sides of the cam bolt portion.

[0006] Another example is the rear cross member for an automobile disclosed in Korean Patent Publication No. (A) 10-2017-0037191 (April 4, 2007). The rear cross member for an automobile comprises a cast member made of aluminum to which suspension parts are connected, and an extruded member connecting the cast member. The rear cross member is characterized by having a metal connector installed between the cast member and the extruded member to join them.

[0007] In the case of the aforementioned conventional technologies, products provided by pressing and welding steel plates or casting aluminum were difficult to manufacture and had problems such as increasing vehicle weight and reducing fuel efficiency due to their weight. Consequently, the industry required a rear cross member with a novel configuration to solve these weight problems.

[0008] Figure 1a shows a photograph of a conventional steel boxing type rear cross member, and Figure 1b shows a photograph of a steel pipe type rear cross member.

[0009] As shown in Fig. 1a, steel upper / lower boxing types and various arm mounting brackets are applied separately, and as shown in Fig. 1b, it can be seen that steel pipe rods and various arm brackets are applied separately. In the case of the existing steel type, a pipe rod type is applied to reduce weight and increase corrosion resistance.

[0010] FIG. 2a shows a photograph of a member to which conventional aluminum gigacasting is applied, and FIG. 2b shows a rear cross member to which conventional aluminum die casting and extrusion are applied.

[0011] As shown in FIGS. 2a and 2b, an integrated gigacasting is being applied using aluminum material to reduce weight compared to steel (Tesla), and since die-casting facilities are limited in Korea, only the side members are die-cast and the center part is made of extruded material.

[0012] FIG. 3 shows an exploded perspective view of a conventional steel upper / lower box type rear cross member. As shown in FIG. 3, CO2 welding is applied after thin sheet forming of the upper / lower box type steel parts, the body mounting corrosion pipe is applied as a separate part, and a separate bracket is applied for connecting various arms.

[0013] Therefore, due to the characteristics of the part, excessive material thickness is applied to individual components to ensure durability, leading to problems such as reduced quality of individual component forming, excessive weight compared to aluminum, increased heat input during CO2 welding due to excessive material thickness (increased bead width, reduced rust prevention performance, increased weight, etc.), and reduced quality caused by thermal deformation during boxing-type CO2 welding. Prior art literature

[0014] Republic of Korea Published Patent No. 10-2020-0132472 Republic of Korea Published Patent No. 10-2017-0037191 The problem to be solved

[0015] Accordingly, the present invention has been devised to solve the aforementioned conventional problems, and according to an embodiment of the present invention, the corrosion resistance is improved by applying an aluminum material, the number of parts is reduced and welding is not required by applying an aluminum extrusion integral type, weight reduction is increased by applying an aluminum extrusion integral type, the strap can be reused after processing, and the degree of freedom of movement of various arm fastening points can be increased by changing the processing part, and the purpose is to provide an extrusion-applied rear cross member for vehicles and a method for manufacturing the same.

[0016] Meanwhile, the technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0017] The first objective of the present invention can be achieved as a rear cross member for a vehicle with an extrusion applied thereto, characterized by comprising: a front member and a center member formed integrally by extrusion, wherein a pair of side members are symmetrically connected to both sides of a front member and a rear member so as to prevent twisting or bending in the front, rear, or left and right directions of the vehicle, the upper part of which is connected to the vehicle body; a front body mounting part formed by extrusion and inserted into each end of the front member and fastened thereto; and a rear body mounting part formed by extrusion and inserted into each end of the rear member and fastened thereto.

[0018] And the above center member is extruded in the left-right direction and then, through post-processing, an upper arm connecting part, an assist arm connecting part, and a lower arm connecting part are integrally provided, and the above front body mounting part and the above rear body mounting part are extruded in the front-rear direction and then, through post-processing, bushing holes are provided, and the center member, the above front body mounting part, and the above rear body mounting part may be characterized by having a reinforcing bulkhead formed when extruded as a whole.

[0019] The second objective of the present invention can be achieved as a rear cross member for a vehicle with an extrusion applied thereto, characterized by comprising: a front member that is extruded and has a pipe shape, wherein a pair of side members are symmetrically connected to both sides of a front member and a rear member so as to prevent twisting or bending in the front, rear, or left and right directions of the vehicle, the upper part of which is connected to the vehicle body; a side member that is extruded and has one side of the front inner surface connected to each of the two ends of the front member; a front body mounting part that is extruded and is connected to one side of the front outer surface of the side member; a rear member that is extruded and has both end surfaces connected to one side of the rear inner surface of the side member; and a rear body mounting part that is extruded and is connected to one side of the rear outer surface of the side member.

[0020] And the front member is extruded in the left-right direction, and the front body mounting part is extruded in the height direction and integrally provided with a bushing hole, and the rear body mounting part is extruded in the front-rear direction and then provided with a bushing hole through post-processing, and the rear member is extruded in the front-rear direction, and the side member is extruded in the height direction, and the side member, the front body mounting part, and the rear body mounting part may be characterized by having a reinforcing bulkhead integrally formed during extrusion.

[0021] The third objective of the present invention can be achieved as a rear cross member for a vehicle with an extrusion applied thereto, characterized by comprising: a front member that is extruded and has a pipe shape and has a front body mounting portion integrally provided, wherein a pair of side members are symmetrically connected to both sides of a front member and a rear member so as to prevent twisting or bending in the front, rear, or left and right directions of the vehicle, the upper part of which is connected to the vehicle body; a side member that is extruded and has a front surface connected to each of the rear ends of the front member; a rear member that is extruded and has both end surfaces connected to one side of the rear inner surface of the side member; and a rear body mounting portion that is extruded and connected to one side of the rear outer surface of the side member.

[0022] In addition, the front member is extruded in the left-right direction, and then a front body mounting part having bushing holes at both ends is integrally provided through bending and hole processing; the rear member is extruded in the front-rear direction, the side member is extruded in the left-right direction, and the rear body mounting part is extruded in the left-right direction and then a bushing hole is provided through post-processing; and the side member and the rear member may be characterized by having a reinforcing bulkhead integrally formed during extrusion. Effects of the invention

[0023] According to the extrusion-applied rear cross member for a vehicle and the method of manufacturing the same according to an embodiment of the present invention, corrosion resistance is improved by applying aluminum material, the number of parts is reduced and welding is not required by applying an aluminum extrusion integral type, weight reduction is increased by applying an aluminum extrusion integral type, the strap can be reused after processing, and the freedom of movement of various arm fastening points can be increased by changing the processing part.

[0024] Meanwhile, the effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present invention belongs from the description below. Brief explanation of the drawing

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1a is a photograph of a conventional steel boxing type rear cross member, Fig. 1b is a photo of a steel pipe type rear cross member, FIG. 2a is a photograph of a member to which conventional aluminum gigacasting is applied, FIG. 2b shows a rear cross member to which conventional aluminum die casting and extrusion are applied, FIG. 3 is an exploded perspective view of a conventional steel upper / lower box type rear cross member, FIG. 4a is a perspective view of a rear cross member for a vehicle with extrusion applied according to a first embodiment of the present invention, FIG. 4b is a plan view of a rear cross member for a vehicle with extrusion applied according to a first embodiment of the present invention, FIG. 4c is a bottom view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention, FIG. 4d is a front view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention, FIG. 4e is a rear view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention, FIG. 4f is a side view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention, FIG. 5 is an exploded perspective view of a rear cross member for a vehicle with extrusion applied according to a first embodiment of the present invention, FIG. 6a is a perspective view of a rear cross member for a vehicle with extrusion applied according to a second embodiment of the present invention, FIG. 6b is a plan view of an extrusion-applied rear cross member for a vehicle according to a second embodiment of the present invention, FIG. 6c is a bottom view of an extrusion-applied rear cross member for a vehicle according to a second embodiment of the present invention, FIG. 6d is a front view of an extrusion-applied rear cross member for a vehicle according to a second embodiment of the present invention, FIG. 6e is a rear view of an extrusion-applied rear cross member for a vehicle according to a second embodiment of the present invention, FIG. 6f is a side view of an extrusion-applied rear cross member for a vehicle according to a second embodiment of the present invention, FIG. 7 is an exploded perspective view of a rear cross member for a vehicle with extrusion applied according to a second embodiment of the present invention, FIG. 8a is a perspective view of a rear cross member for a vehicle with extrusion applied according to a third embodiment of the present invention, FIG. 8b is a plan view of an extrusion-applied rear cross member for a vehicle according to a third embodiment of the present invention, FIG. 8c is a bottom view of an extrusion-applied rear cross member for a vehicle according to a third embodiment of the present invention, FIG. 8d is a front view of an extrusion-applied rear cross member for a vehicle according to a third embodiment of the present invention, FIG. 8e is a rear view of an extrusion-applied rear cross member for a vehicle according to a third embodiment of the present invention, FIG. 8f is a side view of an extrusion-applied rear cross member for a vehicle according to a third embodiment of the present invention, FIG. 9 is an exploded perspective view of a rear cross member for a vehicle with extrusion applied according to the third embodiment of the present invention. Specific details for implementing the invention

[0026] The above objects, other objects, features, and advantages of the present invention will be easily understood through the following preferred embodiments associated with the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to ensure that the spirit of the invention is sufficiently conveyed to a person skilled in the art.

[0027] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Also, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content.

[0028] The embodiments described herein will be explained with reference to cross-sectional and / or plan views, which are exemplary illustrations of the invention. In the drawings, the thicknesses of films and regions are exaggerated for effective explanation of the technical content. Accordingly, the shapes of the exemplary drawings may be modified by manufacturing techniques and / or tolerances, etc. Accordingly, the embodiments of the invention are not limited to the specific shapes depicted but include variations in shape produced according to the manufacturing process. For example, a region depicted as a right angle may be rounded or have a certain curvature. Accordingly, the regions illustrated in the drawings have properties, and the shapes of the regions illustrated in the drawings are intended to illustrate specific shapes of the regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also include their complementary embodiments.

[0029] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, 'comprises' and / or 'comprising' do not exclude the presence or addition of one or more other components to the mentioned components.

[0030] In describing the specific embodiments below, various specific details have been included to explain the invention more specifically and to aid understanding. However, a reader with sufficient knowledge in the art to understand the invention will recognize that it can be used without these various specific details. In some cases, it is noted in advance that commonly known aspects that are not significantly related to the invention have been omitted to prevent unnecessary confusion in describing the invention.

[0032] Hereinafter, the configuration, function, and manufacturing method of an extrusion-applied rear cross member for a vehicle according to an embodiment of the present invention will be described.

[0033] First, FIG. 4a shows a perspective view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention. FIG. 4b shows a top view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention, FIG. 4c shows a bottom view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention, FIG. 4d shows a front view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention, FIG. 4e shows a rear view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention, and FIG. 4f shows a side view of an extrusion-applied rear cross member for a vehicle according to a first embodiment of the present invention.

[0034] In addition, FIG. 5 shows an exploded perspective view of a rear cross member for a vehicle with extrusion applied according to the first embodiment of the present invention.

[0035] The rear cross member for a vehicle with extrusion according to the first embodiment of the present invention is manufactured such that all members are produced through aluminum extrusion, and is configured to include a center member, a pair of front body mounting parts, and a pair of rear body mounting parts, as shown in FIGS. 4a to 4f and FIG. 5.

[0036] In the first embodiment of the present invention, the center member (40) is formed by extrusion of the front member (10), the side member (30), and the rear member (20).

[0037] And as shown in FIG. 5, the center member (40) is extruded in the left and right directions, and then through post-processing (shearing, hole processing), the upper arm connecting part (31), the assist arm connecting part (12), and the lower arm connecting part (22) are integrally formed.

[0038] In addition, when the center member (40) is extruded as a single unit, the reinforcing bulkhead (3) is formed.

[0039] The front body mounting portion (11) according to the first embodiment of the present invention is extruded and configured to be inserted into each end of the front member (10) of the center member (40) and fastened.

[0040] After the front body mounting part (11) is extruded in the front and rear directions, a bushing hole is provided through post-processing (shearing, hole making). When the front body mounting part (11) is also extruded as a single unit, a reinforcing bulkhead (3) is formed.

[0041] The rear body mounting portion (21) according to the first embodiment of the present invention is extruded and configured to be inserted into each end of the rear member (20) of the center member (40) and fastened.

[0042] After the rear body mounting part (21) is extruded in the front and rear directions, a bushing hole is provided through post-processing (shearing, hole making). As shown in FIG. 5, the reinforcing bulkhead (3) is also formed when the rear body mounting part (21) is extruded as a single unit.

[0044] FIG. 6a is a perspective view of a rear cross member for a vehicle with extrusion according to a second embodiment of the present invention. FIG. 6b is a plan view of a rear cross member for a vehicle with extrusion according to a second embodiment of the present invention, and FIG. 6c is a bottom view of a rear cross member for a vehicle with extrusion according to a second embodiment of the present invention.

[0045] FIG. 6d shows a front view of an extrusion-applied rear cross member for a vehicle according to a second embodiment of the present invention, FIG. 6e shows a rear view of an extrusion-applied rear cross member for a vehicle according to a second embodiment of the present invention, and FIG. 6f shows a side view of an extrusion-applied rear cross member for a vehicle according to a second embodiment of the present invention.

[0046] In addition, FIG. 7 shows an exploded perspective view of a rear cross member for a vehicle with extrusion applied according to a second embodiment of the present invention.

[0047] The front member (10) according to the second embodiment of the present invention is extruded and configured to have a pipe shape.

[0048] And the side member (30) according to the second embodiment of the present invention is extruded and configured so that its front inner surface is joined to each of the two end surfaces of the front member (10).

[0049] These side members (30) are extruded in the height direction, and when extruded, a plurality of reinforcing partitions (3) are integrally formed inside, as shown in FIG. 7.

[0050] It can be seen that the side member (30) has a protruding end protruding outward on the front side, and on the rear side, an outer surface curved outward and an inner surface bent outward at a specific angle.

[0051] The front body mounting part (11) according to the second embodiment of the present invention is extruded and coupled to the outer surface of the protruding end of the front outer surface of the side member (30).

[0052] As shown in FIG. 7, the front body mounting part (11) is extruded in the height direction, and it can be seen that the bushing hole and the reinforcing bulkhead are integrally provided during extrusion molding.

[0053] The rear member (20) according to the second embodiment of the present invention is extruded and configured so that both end surfaces are joined to the rear inner surface of the side member (20).

[0054] As shown in FIG. 7, this rear member (20) is extruded in the front-rear direction and has a shape in which both ends are bent in multiple stages toward the upper side, and during extrusion, a plurality of reinforcing partitions are integrally provided inside.

[0055] The rear body mounting portion (21) is extruded and connected to the rear outer end surface of the side member (30). After the rear body mounting portion (21) is extruded in the front-rear direction, a bushing hole is provided through post-processing. The reinforcing bulkhead is also integrally formed during extrusion of the rear body mounting portion (21).

[0056] And as shown in FIG. 7, it can be seen that separate assist arm connecting part (12), upper arm connecting part (31), and lower arm connecting part (22) are each extruded and combined.

[0058] FIG. 8a is a perspective view of a rear cross member for a vehicle with extrusion according to a third embodiment of the present invention. FIG. 8b is a plan view of a rear cross member for a vehicle with extrusion according to a third embodiment of the present invention. FIG. 8c is a bottom view of a rear cross member for a vehicle with extrusion according to a third embodiment of the present invention.

[0059] Additionally, FIG. 8d shows a front view of an extrusion-applied rear cross member for a vehicle according to a third embodiment of the present invention, FIG. 8e shows a rear view of an extrusion-applied rear cross member for a vehicle according to a third embodiment of the present invention, and FIG. 8f shows a side view of an extrusion-applied rear cross member for a vehicle according to a third embodiment of the present invention.

[0060] FIG. 9 is an exploded perspective view of a rear cross member for a vehicle with extrusion applied according to the third embodiment of the present invention.

[0061] The front member (10) according to the third embodiment of the present invention is extruded in the left and right directions and has a pipe shape, and the front body mounting part (11) is integrally provided. The front member (10) is manufactured by extruding, then performing shear processing and bending processing so that both ends are bent toward the front, and then processing bushing holes through hole processing.

[0062] A side member (30) according to the third embodiment of the present invention is extruded and configured so that its front end surface is connected to each of the rear ends of the front member (10).

[0063] The side member (30) is extruded in the left and right directions, and a plurality of reinforcing partitions (3) are formed integrally during extrusion. The rear end is curved upwards overall.

[0064] The rear member (20) according to the third embodiment of the present invention is extruded in the front-rear direction and configured so that both end surfaces are joined to one side of the rear inner surface of the side member. Additionally, the rear member (20) may be configured to have protruding ends at the lower ends of both ends to increase the joining area with the side member. Furthermore, the overall shape has both ends curved upward and the height gradually increases toward both ends. As shown in FIG. 9, the rear member (20) also has a plurality of reinforcing partitions (3) integrally formed during extrusion.

[0065] In addition, the rear body mounting part (21) is extruded in the left-right direction and configured to be coupled to one side of the rear outer surface of the side member (20). After the rear body mounting part (21) is extruded in the left-right direction, a bushing hole is provided through post-processing, and the inner end surface has a shape that can be shaped to match the outer rear corner of the side member (30).

[0066] And as shown in FIG. 9, it can be seen that separate assist arm connecting part (12), upper arm connecting part (31), and lower arm connecting part (22) are each extruded and combined.

[0068] In addition, the device and method described above are not limited to the configurations and methods of the embodiments described above; rather, all or part of each embodiment may be selectively combined to allow for various modifications to be made. Explanation of the symbols

[0069] 3: Reinforced bulkhead 10: Front Member 11: Front Member Body Mounting Department 12: Assist arm connection part 20: Rear member 21: Rear member body mounting section 22: Lower arm connection part 30: Side member 31: Upper arm connection part 40: Center member 100: Extrusion-applied automotive rear crossmember

Claims

Claim 1 A rear cross member of a vehicle having a pair of side members symmetrically connected to both sides of a front member and a rear member so as to prevent twisting or bending of the vehicle in the front, rear, or left and right directions by being connected to the vehicle body at its upper end, comprising: a center member in which the front member, the side member, and the rear member are integrally formed by extrusion; and a front body mounting part that is extruded and inserted into and fastened to each of both ends of the front member. and a rear body mounting part that is extruded and inserted into and fastened to each of both ends of the rear member; wherein the center member is extruded in the left-right direction and then integrally provided with an upper arm fastening part, an assist arm fastening part, and a lower arm fastening part through post-processing, and the front body mounting part and the rear body mounting part are extruded in the front-rear direction and then provided with bushing holes through post-processing, and when the center member, the front body mounting part, and the rear body mounting part are extruded as a whole, a reinforcing bulkhead is formed, and also when the center member is extruded as a whole, a reinforcing bulkhead is formed, and the front body mounting part is extruded and configured to be inserted into and fastened to each of both ends of the front member of the center member, and when the front body mounting part is extruded in the front-rear direction, a bushing hole is provided through post-processing, and when the front body mounting part is extruded as a whole, a reinforcing bulkhead is formed, and the rear body mounting part is extruded and the center member's A rear cross member for an extrusion-applied vehicle, characterized in that it is configured to be inserted into and fastened at each end of the rear member, the rear body mounting portion is extruded in the front-rear direction and then provided with a bushing hole through post-processing, and the rear body mounting portion is formed as a reinforcing bulkhead when extruded integrally. Claim 2 delete Claim 3 A rear cross member of a vehicle having a pair of side members symmetrically connected to both sides of a front member and a rear member so as to prevent twisting or bending of the vehicle in the front, rear, or left and right directions by connecting the upper part to the vehicle body, comprising: a front member that is extruded and has a pipe shape; a side member that is extruded and has one side of its front inner surface connected to each of both ends of the front member; a front body mounting part that is extruded and is connected to one side of the front outer surface of the side member; a rear member that is extruded and has both end surfaces connected to one side of the rear inner surface of the side member; and a rear body mounting part that is extruded and is connected to one side of the rear outer surface of the side member.It includes, wherein the front member is extruded in the left-right direction, and the front body mounting part is extruded in the height direction and integrally provided with a bushing hole, and the rear body mounting part is extruded in the front-rear direction and then provided with a bushing hole through post-processing, the rear member is extruded in the front-rear direction, and the side member is extruded in the height direction, and the side member, the front body mounting part, and the rear body mounting part have reinforcing bulkheads integrally formed during extrusion, and the side member is extruded in the height direction and, during extrusion, a plurality of reinforcing bulkheads are integrally formed inside, and the side member has a protruding end protruding outwardly on the front side and an outer surface curved outwardly and an inner surface bent outwardly at a specific angle on the rear side, the front body mounting part is extruded and is coupled to the outer surface of the protruding end on the front outer surface of the side member, and the front body mounting part is extruded in the height direction, and during extrusion, the bushing hole and the reinforcing bulkhead are integrally formed A rear cross member for an extrusion-applied vehicle, characterized in that the rear member is extruded and both end surfaces are joined to the rear inner surface of the side member, the rear member is extruded in the front-rear direction and has a shape in which both ends are multi-stage bent toward the upper side, and during extrusion, a plurality of reinforcing bulkheads are integrally provided inside, the rear body mounting part is extruded and joined to the rear outer end surface of the side member, the rear body mounting part is extruded in the front-rear direction and then a bushing hole is provided through post-processing, the reinforcing bulkheads are also integrally formed during extrusion of the rear body mounting part, and separate assist arm fastening part, upper arm fastening part, and lower arm fastening part are each extruded and joined. Claim 4 delete Claim 5 A rear cross member of a vehicle having a pair of side members symmetrically connected to both sides of a front member and a rear member so that the upper part is connected to the vehicle body to prevent twisting or bending in the front, rear, or left and right directions of the vehicle, comprising: a front member that is extruded and has a pipe shape and is integrally provided with a front body mounting portion; a side member that is extruded and whose front surface is connected to each of the rear ends of the front member; and a rear member that is extruded and whose end surfaces are connected to one side of the rear inner surface of the side member. and includes a rear body mounting part that is extruded and coupled to one side of the rear outer surface of the side member; wherein the front member is extruded in the left-right direction, and then a front body mounting part having bushing holes at both ends is integrally provided through bending and hole processing; the rear member is extruded in the front-rear direction, the side member is extruded in the left-right direction, and the rear body mounting part is extruded in the left-right direction and then has bushing holes provided through post-processing; the side member and the rear member have reinforcing bulkheads integrally formed during extrusion, the rear member is extruded in the front-rear direction and is configured so that the cross-sections of both ends are coupled to one side of the rear inner surface of the side member, and is configured so that protruding ends are provided at the lower ends of both ends of the rear member to increase the coupling area with the side member, and has a shape in which both ends are curved upward and the height gradually increases toward both ends, and a plurality of reinforcing bulkheads are integrally formed during the extrusion of the rear member, and the rear A rear cross member for an extrusion-applied vehicle, characterized in that the body mounting portion is extruded in the left-right direction and configured to be coupled to one side of the rear outer surface of the side member, and after being extruded in the left-right direction, a bushing hole is provided through post-processing, and the inner end surface has a shape that can be shaped to match the outer rear corner of the side member, and separate assist arm fastening portion, upper arm fastening portion, and lower arm fastening portion are each extruded and coupled. Claim 6 delete

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