Method of manufacturing rear vehicle body frame member and rear vehicle body structure

Abstract

To reduce a projection surface at the time of casting and to improve rigidity against an input load at the time of collision.SOLUTION: At least one rib side 116a is integrally molded so as to project in the vehicle front or rear direction on a body frame member 100 integrally molded by casting in a state that a right side rear suspension tower part 110 and a left side rear suspension tower part 120 are connected by a connecting part 130. The vehicle body frame member 100 is cast in a posture in which a rib 116a protrudes upward or downward.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a manufacturing method for a rear body frame member of, for example, an automobile, and a rear body structure. [Background technology]

[0002] For example, rear suspension towers are provided on the left and right sides of the rear of an automobile, to which the upper parts of the dampers of the suspension system are attached. For example, Patent Document 1 discloses that a reinforcing member including the rear suspension towers is integrally molded by aluminum die casting. Ribs are also integrally molded into this reinforcing member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-44885 Summary of the Invention [Problem to be solved by the invention]

[0004] To reduce the number of vehicle body parts, it is conceivable to obtain a rear body frame member by integrally casting the right and left rear suspension towers, with the towers connected by an intermediate connector. Ribs must be integrally molded into such a frame member to ensure rigidity.

[0005] Incidentally, the skeletal member is a large member because it connects the left and right rear suspension tower sections with connecting parts. In order to make the mold used to mold such a large skeletal member as small as possible, it is desirable to set the direction in which the projection surface of the skeletal member becomes smaller as the movement direction of the mold.

[0006] As mentioned above, the size of the skeletal member needs to be taken into consideration when setting the direction of mold movement, but at the same time, there is also a demand to set the orientation of the rib so that it prioritizes the reinforcing effect when the rib is molded integrally with the skeletal member.

[0007] The present disclosure has been made in consideration of the above points, and an object thereof is to reduce the projection area during casting and to improve rigidity against input loads during a collision. [Means for solving the problem]

[0008] To achieve the above object, one aspect of the present disclosure can be based on a method for manufacturing a rear body frame member in which a rear suspension tower section on one side in the vehicle width direction and a rear suspension tower section on the other side in the vehicle width direction are connected by a connecting section, and at least one rib that protrudes forward or rearward of the vehicle when assembled to the vehicle is integrally molded. In this manufacturing method, a mold is prepared whose dividing direction is the up-down direction, and the rear body frame member is cast using the mold in a state where it is rotated in a side view of the vehicle so that the rib protrudes upward or downward and so that the dimension of the projection surface from above in a direction perpendicular to the vehicle width direction is shorter than the dimension of the projection surface in a plan view of the vehicle in the direction perpendicular to the vehicle width direction.

[0009] With this configuration, the rear suspension tower section on one side in the vehicle width direction, the rear suspension tower section on the other side in the vehicle width direction, and the connecting section are molded as a single unit, thereby reducing the number of parts. Furthermore, by integrally molding the rib that protrudes forward or rearward of the vehicle with the rear-body frame member, the rear-body frame member can be made to have high rigidity against the input of an impact load from behind, for example. When this rear-body frame member is cast, the rib is oriented to protrude upward or downward, and the dimension of the projection surface from above in a direction perpendicular to the vehicle width direction is shorter than the dimension of the projection surface in a plan view of the vehicle in a direction perpendicular to the vehicle width direction. This reduces the projection surface during casting, and therefore requires a smaller mold for molding.

[0010] The ribs may extend along the longitudinal direction of the vehicle or may be inclined relative to the longitudinal direction of the vehicle. By integrally molding such ribs, sufficient rigidity can be ensured.

[0011] The rib may be continuous from at least one of the rear suspension tower section on one side in the vehicle width direction and the rear suspension tower section on the other side in the vehicle width direction to the connecting section, thereby connecting the rear suspension tower section and the connecting section with the rib, thereby further increasing the rigidity of the vehicle body frame member.

[0012] The vehicle body frame member may include a connecting member that connects an upper portion of the rear suspension tower section on one side in the vehicle width direction to an upper portion of the rear suspension tower section on the other side in the vehicle width direction. In this case, the connecting member can be integrally molded with the upper portion of the rear suspension tower section on one side in the vehicle width direction and the upper portion of the rear suspension tower section on the other side in the vehicle width direction, and the connecting member is positioned in the extension direction of the rib, so that the projection surface of the vehicle body frame member including the connecting member can be reduced when the rib is in a position where it protrudes in the vertical direction.

[0013] The rib may include an inner rib integrally molded on the vehicle interior side of the rear suspension tower section and an outer rib integrally molded on the vehicle exterior side of the rear suspension tower section. In this case, the connecting member may be disposed at a position spaced apart in a direction parallel to the extension direction of the ribs from an upper portion of the rear suspension tower section on one side in the vehicle width direction and an upper portion of the rear suspension tower section on the other side in the vehicle width direction.

[0014] In another aspect of the present invention, a rear body structure can be provided in which a rear suspension tower section on one side in the vehicle width direction and a rear suspension tower section on the other side in the vehicle width direction are connected by a connecting section, and at least one rib protruding forward or rearward of the vehicle is integrally molded. The rear body structure includes a recessed section that is open to the front of the vehicle and recessed toward the rear of the vehicle, and the upper and lower wall sections of the recessed section extend in the same direction as the rib. This allows the rib and recessed section to be easily molded integrally using a mold that moves up and down while reducing the projected area during casting. [Effects of the Invention]

[0015] As described above, according to the present disclosure, the projection surface of a body frame member in which a rear suspension tower section on one side of the vehicle width direction and a rear suspension tower section on the other side of the vehicle width direction are connected by a connecting section can be reduced during casting, and rigidity against input loads during a collision can be improved. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a side view of an automobile equipped with a vehicle body structure according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the vehicle body structure. [Figure 3] FIG. 3 is a bottom view of the vehicle body structure. [Figure 4] FIG. 4 is a perspective view of the rear frame member. [Figure 5] FIG. 5 is a plan view of the rear framework member. [Figure 6] FIG. 6 is a front view of the rear frame member. [Figure 7] FIG. 7 is a right side view of the rear framework member. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. [Figure 9] FIG. 9 is a side view showing the state immediately after casting. [Figure 10] FIG. 10 is a view corresponding to FIG. 9 according to a modified example of the embodiment. [Figure 11] FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0018] 1 is a side view of an automobile 1 equipped with a rear vehicle-body structure A according to an embodiment of the present invention. In the description of this embodiment, the front side of the vehicle will be simply referred to as the "front," the rear side of the vehicle will be simply referred to as the "rear," the right side of the vehicle will be simply referred to as the "right," and the left side of the vehicle will be simply referred to as the "left." The left-right direction of the vehicle is the vehicle width direction.

[0019] The automobile 1 may be, for example, a passenger automobile, such as a coupe, hatchback, or sedan. The automobile 1 may also be an automobile equipped with an internal combustion engine that generates driving force transmitted to the drive wheels, an electric automobile equipped with a traction motor that generates driving force transmitted to the drive wheels, or a hybrid automobile in which driving force transmitted to the drive wheels is generated by an internal combustion engine and a driving force generating motor. The internal combustion engine and the motor constitute a powertrain PT.

[0020] A bonnet hood 2 is provided at the front of the automobile 1. A front space R1 is provided below the bonnet hood 2, in which a powertrain PT is mounted as needed. A rear hood 3 is provided at the rear of the automobile 1. A rear space R2 capable of accommodating luggage is provided below the rear hood 3. A powertrain (not shown) may be mounted in the rear space R2 without mounting the powertrain PT in the front space R1. In this case, the front space R1 can be used as a space for accommodating luggage. Powertrains may also be mounted in both the front space R1 and the rear space R2.

[0021] A left door 4 and a right door (not shown) that can be opened and closed are provided on the left and right sides of the automobile 1. The automobile 1 also has front wheels 7 and rear wheels 8 on the left and right sides, respectively. At least one of the front wheels 7 and the rear wheels 8 can be a drive wheel.

[0022] Between the front space R1 and the rear space R2, a passenger compartment R3 is provided as a living space for occupants. As shown in Fig. 2, the automobile 1 includes a floor panel 10 that forms the floor surface of the passenger compartment R3, and a dash panel 20 that forms the front wall of the passenger compartment R3. The rear body structure A of the automobile 1 also includes an inclined panel 16 that extends upward from the rear end of the floor panel 10 and is inclined so that it is positioned further rearward as it goes upward, and a rear panel 17 that extends rearward from the upper end of the inclined panel 16.

[0023] A tunnel portion 11 that bulges upward and extends in the front-to-rear direction is formed in the center of the floor panel 10 in the left-to-right direction. The automobile 1 also has a right side sill 12 that extends in the front-to-rear direction along the right edge of the floor panel 10, and a left side sill 13 that extends in the front-to-rear direction along the left edge of the floor panel 10. A right hinge pillar 12a that extends upward is provided in the front of the right side sill 12. The right hinge pillar 12a is a member that supports the right door. A left hinge pillar 13a that extends upward is provided in the front of the left side sill 13. The left hinge pillar 13a is a member that supports the left door 4.

[0024] The front end of the tunnel portion 11 is located at the front end of the floor panel 10, and the rear end of the tunnel portion 11 is located at the rear end of the floor panel 10. Therefore, the tunnel portion 11 has a shape that extends continuously from the front end to the rear end of the floor panel 10.

[0025] The automobile 1 is a right-hand drive vehicle. Therefore, the automobile 1 is provided with a passenger seat 30 as a left seat (seat) and a driver's seat 40 as a right seat (seat) on the left and right sides of the tunnel section 11 of the floor panel 10, respectively. Specifically, the passenger seat 30 is provided on the left side of the tunnel section 11 of the floor panel 10, and the passenger seat 30 is disposed between the tunnel section 11 and the left side side sill 13. The driver's seat 40 is provided on the right side of the tunnel section 11 of the floor panel 10, and the driver's seat 40 is disposed between the tunnel section 11 and the right side side sill 12. Therefore, the passenger seat 30 and the driver's seat 40 are disposed side by side in the left-right direction, sandwiching the tunnel section 11 therebetween. Note that the automobile 1 may be a left-hand drive vehicle, in which case the driver's seat 40 may be disposed on the left side and the passenger seat 30 may be disposed on the right side. Furthermore, a rear seat may be disposed behind the driver's seat 40 and the passenger seat 30.

[0026] The dash panel 20 extends upward and laterally from the front end of the floor panel 10 and separates the vehicle interior R3 from a front space R1 located forward of the vehicle interior R3. The front end of the tunnel section 11 is connected to the center of the lower portion of the dash panel 20 in the lateral direction.

[0027] A front casting member 50 is provided at the front of the automobile 1. The front casting member 50 includes a right front side frame 60, a left front side frame 70, and a connecting portion 80 that connects the right front side frame 60 and the left front side frame 70. A front space R1 is provided between the right front side frame 60 and the left front side frame 70. The right front side frame 60, the left front side frame 70, and the connecting portion 80 are integrally molded by casting. The rear portions of the left front side frame 70 and the right front side frame 60 are fixed to the dash panel 20. The rear portion of the connecting portion 80 is fixed to the dash panel 20 and the front portion of the tunnel section 11. When fixing the right front side frame 60, the left front side frame 70 and the connecting portion 80 to the dash panel 20 and the tunnel portion 11, various fixing methods can be applied, such as fixing by welding or fastening using fastening members (including, for example, self-piercing rivets), and any one of these fixing methods may be used alone, or any two or more of these fixing methods may be used in combination.

[0028] The rear body structure A includes a rear body frame member 100. That is, the rear body frame member 100 is provided above the inclined panel 16 and is integrally molded by casting. The rear body frame member 100 includes a right rear suspension tower section (rear suspension tower section on one side in the vehicle width direction) 110, a left rear suspension tower section (rear suspension tower section on the other side in the vehicle width direction) 120, and a connecting section 130. The connecting section 130 connects the right rear suspension tower section 110 and the left rear suspension tower section 120, and is integrally molded by casting with the right rear suspension tower section 110 and the left rear suspension tower section 120 connected by the connecting section 130. When manufacturing the rear body frame member 100, for example, an aluminum die casting method can be used.

[0029] The front end of a right rear frame 19a extending in the front-to-rear direction is connected to the rear of the right rear suspension tower section 110. The right rear frame 19a is positioned more inboard than the right side sill 12 and is positioned higher than the right side sill 12. The front end of a left rear frame 19b extending in the front-to-rear direction is connected to the rear of the left rear suspension tower section 120. The left rear frame 19b is positioned more inboard than the left side sill 13 and is positioned higher than the left side sill 13. A rear panel 17 is provided to connect the right rear frame 19a and the left rear frame 19b.

[0030] As shown in Figures 4 to 6, the right rear suspension tower section 110 has a right wheel house section 111 that forms a wheel house for a right rear wheel (not shown). The right wheel house section 111 extends in the up-down and front-rear directions and has a concave shape that is recessed toward the interior and front of the vehicle. Both the rear and bottom sides of this right wheel house section 111 are open, giving the right wheel house section 111 a dome shape.

[0031] The right wheel house section 111 has a right bulging section 111a that bulges out toward the vehicle interior, and a right plate section 111b that extends in the up-down and front-rear directions from the top of the right bulging section 111a to the front. A right damper mounting section 112 is provided near the top of the right bulging section 111a. The right damper mounting section 112 is a plate-shaped section to which the top of a damper included in a rear suspension device (not shown) is attached, and extends in the front-rear and left-right directions. An opening 112a is formed in the right damper mounting section 112.

[0032] A right flange portion 111c is formed on the periphery of the right side plate portion 111b. The right flange portion 111c extends continuously from the upper portion of the right wheel house portion 111, passing through the front portion and down to the lower portion. A right front connection portion 113 is formed on the lower front side of the right wheel house portion 111, and is connected to the rear end portion of the right side sill 12. Furthermore, a right rear connection portion 114 is formed on the lower rear side of the right wheel house portion 111, and is connected to the front end portion of the right rear frame 19a. The right rear connection portion 114 is located on the vehicle interior side and above the right front connection portion 113.

[0033] A right load transmission part 115 is provided at the bottom of the right wheel house part 111, extending from the right front connection part 113 to the right rear connection part 114. The right load transmission part 115 is inclined so that it is positioned further outboard and lower towards the front.

[0034] The left rear suspension tower section 120 and the right rear suspension tower section 110 have a bilaterally symmetrical structure. Specifically, when an imaginary line passing through the center of the left-right direction of the automobile 1 and extending in the longitudinal direction is taken as the center of symmetry, the left rear suspension tower section 120 is line-symmetrical with the right rear suspension tower section 110, and the right rear suspension tower section 110 is line-symmetrical with the left rear suspension tower section 120.

[0035] That is, the left rear suspension tower section 120 has a left wheel house section 121 that forms a wheel house for the left rear wheel 8 (shown in FIG. 1). The left wheel house section 121 extends in the up-down and front-to-rear directions and has a concave shape that is recessed toward the interior and front of the vehicle. Both the rear and bottom sides of this left wheel house section 121 are open, which gives the left wheel house section 121 a dome shape.

[0036] The left wheel house section 121 has a left bulging section 121a that bulges out toward the vehicle interior, and a left side plate section 121b that extends in the up-down and front-rear directions from the top of the left bulging section 121a to the front. A left damper mounting section 122 is provided near the top of the left bulging section 121a. The left damper mounting section 122 is a section to which the top of a damper provided in a rear suspension device (not shown) is attached, and has an opening 122a.

[0037] A left flange portion 121c is formed on the periphery of the left side plate portion 121b. The left flange portion 121c extends continuously from the upper portion of the left wheel house portion 121 through the front portion to the lower portion. A left front connection portion 123 is formed on the lower front side of the left wheel house portion 121, and is connected to the rear end portion of the left side sill 13. Furthermore, a left rear connection portion 124 is formed on the lower rear side of the left wheel house portion 121, and is connected to the front end portion of the left rear frame 19b. The left rear connection portion 124 is located on the vehicle interior side and above the left front connection portion 123.

[0038] A left load transmission part 125 is provided at the bottom of the left wheel house part 121, extending from the left front connection part 123 to the left rear connection part 124. The left load transmission part 125 is inclined so that it is positioned further outboard and lower as it goes forward.

[0039] Therefore, for example, an impact load during a rear-end collision is input to the right wheel housing portion 111 via the right rear frame 19a. The impact load input to the right wheel housing portion 111 is transmitted to the right side sill 12 via the right rear connection portion 114, the right load transmission portion 115, and the right front connection portion 113. The impact load during a rear-end collision is input to the left wheel housing portion 121 via the left rear frame 19b. The impact load input to the left wheel housing portion 121 is transmitted to the left side sill 13 via the left rear connection portion 124, the left load transmission portion 125, and the left front connection portion 123.

[0040] As described above, the rear body frame member 100 is a member that receives the impact load during a rear collision and transmits it to the right side sill 12 and the left side sill 13, and therefore needs to have high rigidity against the input of the impact load. For this reason, one or more ribs are molded integrally with the rear body frame member 100.

[0041] A first right inner rib 116a, a second right inner rib 116b, a third right inner rib 116c, a fourth right inner rib 116d, and a fifth right inner rib 116e are integrally molded on the vehicle interior side of the right wheel house section 111. For example, as shown in Fig. 8, the first right inner rib 116a, the second right inner rib 116b, the third right inner rib 116c, the fourth right inner rib 116d, and the fifth right inner rib 116e are ribs that are inclined with respect to the front-to-rear direction.

[0042] A plurality of first right inner ribs 116a are provided, extending continuously from the right side plate portion 111b to the front portion of the right bulging portion 111a and protruding forward. The plurality of first right inner ribs 116a are provided at intervals from one another in the up-down direction. The uppermost first right inner rib 116a is located near the right damper mounting portion 112. The lowermost first right inner rib 116a is located in the middle of the right bulging portion 111a in the up-down direction.

[0043] A plurality of second right inner ribs 116b are provided, extending continuously from the right side plate portion 111b to the right load transmission portion 115 and protruding forward. The plurality of second right inner ribs 116b are provided at intervals from one another in the front-to-rear direction. The foremost second right inner rib 116b is located near the front of the right load transmission portion 115. The rearmost second right inner rib 116b is located near the rear of the right load transmission portion 115.

[0044] The third right inner rib 116c is provided at the rear portion of the right bulge portion 111a, extends toward the vehicle interior, and protrudes forward. The fourth right inner rib 116d extends continuously from the upper surface of the right front connecting portion 113 to the front portion of the right side plate portion 111b and protrudes forward. The multiple fourth right inner ribs 116d are provided at intervals from one another in the left-right direction. The fifth right inner rib 116e extends from the fourth right inner rib 116d on the right side to the right flange portion 111c and protrudes forward. The multiple fifth right inner ribs 116e are provided at intervals from one another in the up-down direction.

[0045] Although not shown, the inner rib integrally molded with the body frame member 100 may be integrally molded so as to protrude rearward. The number of inner ribs may be one. Any one or more of the first right inner rib 116a, the second right inner rib 116b, the third right inner rib 116c, the fourth right inner rib 116d, and the fifth right inner rib 116e may be integrally molded with the body frame member 100. The positions of the inner ribs 116a to 116e are not limited to those shown in the drawings, and may be any positions.

[0046] As shown in FIG. 7, outer ribs 117a-117d are integrally molded on the vehicle exterior side of the right wheel house portion 111. That is, in this embodiment, the ribs of the vehicle body frame member 100 include inner ribs 116a-116e and outer ribs 117a-117d. Specifically, a first right outer rib 117a, a second right outer rib 117b, a third right outer rib 117c, and a fourth right outer rib 117d are integrally molded on the vehicle exterior side of the right wheel house portion 111. The first right outer ribs 117a are provided in plurality and extend from the right side plate portion 111b toward the vehicle exterior and protrude rearward. The multiple first right outer ribs 117a are provided spaced apart from one another in the up-down direction. The second right outer rib 117b extends from the right bulging portion 111a toward the vehicle exterior and protrudes rearward. The multiple second right outer ribs 117b are spaced apart from one another in the up-down direction. The third right outer rib 117c extends from the right bulge 111a to the right side plate 111b and protrudes forward. The multiple third right outer ribs 117c are spaced apart from one another in the up-down direction. The fourth right outer rib 117d extends from the right load transfer portion 115 toward the exterior of the vehicle and protrudes rearward. The multiple fourth right outer ribs 117d are spaced apart from one another in the front-rear direction.

[0047] Although not shown, the outer rib integrally molded with the body frame member 100 may be integrally molded so as to protrude forward. The number of outer ribs may be one. Any one or more of the first right outer rib 117a, the second right outer rib 117b, the third right outer rib 117c, and the fourth right outer rib 117d may be integrally molded with the body frame member 100. The positions of the outer ribs 117a to 117d are not limited to those shown in the drawings, and may be any positions.

[0048] As shown in Figures 5 and 6, on the inside of the left wheel house section 121, similar to the right wheel house section 111, a first left inner rib 126a, a second left inner rib 126b, a third left inner rib 126c, a fourth left inner rib 126d and a fifth left inner rib 126e are integrally molded.

[0049] As shown in Figure 4, a first left outer rib 127a, a second left outer rib 127b, a third left outer rib 127c, and a fourth left outer rib 127d are integrally molded on the outside of the left wheel house portion 121, similar to the right wheel house portion 111.

[0050] 5 and 6, the connecting portion 130 extends in the left-right direction from a longitudinally central portion of the lower portion of the right rear suspension tower portion 110 to a longitudinally central portion of the lower portion of the left rear suspension tower portion 120. As also shown in FIG. 4, a plurality of first lower ribs 130a that protrude forward and extend in the up-down direction are provided at intervals in the left-right direction on the front surface of the connecting portion 130. Furthermore, a curved plate portion 131 that curves upward is provided at the left-right central portion of the connecting portion 130. A plurality of second lower ribs 131a that protrude upward and extend forward are provided at intervals in the circumferential direction of the curved plate portion 131 on the upper surface of the curved plate portion 131.

[0051] The rear vehicle-body frame member 100 is provided with a long rib 140 that continues from the right rear suspension tower section 110 to the connecting section 130 and also continues to the left rear suspension tower section 120. The right portion of the long rib 140 is molded integrally with the right bulging section 111a and the front portion of the right side plate section 111b. The left portion of the long rib 140 is molded integrally with the left bulging section 121a and the front portion of the left side plate section 121b. The long rib 140 may be a rib that continues from the right rear suspension tower section 110 to the connecting section 130, or may be a rib that continues from the left rear suspension tower section 120 to the connecting section 130.

[0052] 11, the right rear connection portion 114 is formed as a recessed portion that is open to the front and recessed to the rear. The right rear connection portion 114 has an upper wall portion 114a and a lower wall portion 114b, a rear wall portion 114c that extends from the rear end of the upper wall portion 114a to the rear end of the lower wall portion 114b, and left and right side wall portions 114d. The upper wall portion 114a and the lower wall portion 114b of the right rear connection portion 114 both extend in the front-to-rear direction, and more specifically, extend in the same direction (substantially parallel) as the ribs 116a to 116e, 117a to 117d, 126a to 126e, 127a to 127d, 130a, 131a, and 140.

[0053] The right rear connecting portion 114 is hollow, making it lightweight and highly strong. By connecting the front end of the right rear frame 19a to this right rear connecting portion 114, the support rigidity of the front end of the right rear frame 19a can be increased.

[0054] (Method for manufacturing rear body frame member 100) Next, a manufacturing method of the rear body frame member 100 will be described. When the rear body frame member 100 is assembled to the vehicle, it takes the position shown in Fig. 7 when viewed from the side. Fig. 7 shows the state after assembly to the vehicle is complete (assembled state), and in this side view of the rear body frame member 100 in this assembled state, a virtual line L1 is drawn passing through the center point P1 of the rear body frame member 100. The angle of line L1 with respect to the vertical plane is set to 0° and the angle with respect to the horizontal plane to be 90° so that the line L1 extends vertically when the rear body frame member 100 is in the assembled state.

[0055] On the other hand, during casting, the angle of the rear body frame member 100 is set so that the straight line L1 is inclined, as shown in Fig. 9. In Fig. 9, the rear body frame member 100 is cast in a position in which the ribs 116a to 116e, 117a to 117d, 130a, 131a, and 140 protrude upward or downward. Although not shown in Fig. 9, the rear body frame member 100 is cast in a position in which the upper wall portion 114a and the lower wall portion 114b of the right rear connecting portion 114 shown in Fig. 11 extend upward.

[0056] Specifically, when manufacturing the rear body frame member 100, a first mold 200 and a second mold 201 are prepared, with the dividing direction being vertical. The first mold 200 is arranged as an upper mold, and the second mold 201 is arranged as a lower mold. The second mold 200 is provided with a mold drive device (not shown), which moves vertically to switch between a mold closed state in contact with the second mold 201 and a mold open state in which the second mold 201 is spaced upward. Each of the first mold 200 and the second mold 201 has a molding surface (not shown), and a cavity (not shown) formed by the molding surface of the first mold 200 and the molding surface of the second mold 201 is filled with molten aluminum alloy. The shapes of the molding surfaces of the first mold 200 and the second mold 201 are set so that the rear body frame member 100 can be cast in the position shown in FIG. 9.

[0057] First, the first mold 200 and the second mold 201 are closed. Then, a molten aluminum alloy is filled into the cavity, and after a predetermined time has passed, the molten aluminum alloy is molded by the molding surfaces of the first mold 200 and the second mold 201 and solidified. Then, the first mold 200 is moved upward to an open mold state. At this time, the ribs 116a to 116e, 117a to 117d, 126a to 126e, 127a to 127d, 130a, 131a, and 140 are in a position where they protrude upward or downward, so that the setting of a slide mold or the like is not required to mold the ribs 116a to 116e, 117a to 117d, 126a to 126e, 127a to 127d, 130a, 131a, and 140.

[0058] When the mold is opened, the rear body frame member 100 is obtained, molded in the position shown in Fig. 9. At this time, the angle α formed by the line L1 and the horizontal plane S1 is less than 90°, and the line L1 is inclined at the angle α with respect to the horizontal plane S1. When the angle formed by the line L1 and the horizontal plane S1 is α, the dimension of the projection surface of the rear body frame member 100 from above in the direction perpendicular to the vehicle width direction (maximum dimension A2 shown in Fig. 9) is shorter than the dimension of the projection surface of the rear body frame member 100 in a plan view of the vehicle in the direction perpendicular to the vehicle width direction (maximum dimension A1 shown in Figs. 5 and 7). That is, in this embodiment, the rear body frame member 100 is cast using the first mold 200 and the second mold 201 while the rear body frame member 100 is rotated in a vehicle side view so that the ribs 116a-116e, 117a-117d, 126a-126e, 127a-127d, 130a, 131a, and 140 protrude upward or downward, and so that the dimension A2 in the direction perpendicular to the vehicle width direction (left-right direction) of the projection plane from above is shorter than the dimension A1 in the direction perpendicular to the vehicle width direction of the projection plane in a plan view of the rear body frame member 100 (plan view of the rear body frame member 100 in a state assembled to the vehicle). At this time, the right rear connection portion 114 shown in FIG. 11 is also integrally molded. 5, 7, and 9 are different in scale, the relationship between the dimensions A1 and A2 does not satisfy the above-mentioned relationship, but if they are made to the same scale, the relationship satisfies the above-mentioned relationship.

[0059] For example, when the angle between the straight line L1 and the horizontal plane S1 exceeds a predetermined angle α or is smaller than α, the dimension A2 of the rear body frame member 100 in the direction perpendicular to the vehicle width direction of the plane projected from above becomes longer than when the angle is α. If the dimension A2 of the rear body frame member 100 in the direction perpendicular to the vehicle width direction of the plane projected from above during casting becomes longer, the molds 200 and 201 become larger, making manufacturing difficult. In short, in the manufacturing method according to this embodiment, the angle between the straight line L1 and the horizontal plane S1 is set to α, and the orientation of the rear body frame member 100 is set so that the dimension A2 of the plane projected from above in the direction perpendicular to the vehicle width direction is shorter. This makes it possible to reduce the size of the first mold 200 and the second mold 201, thereby facilitating the manufacturing of the rear body frame member 100.

[0060] (Modification of the embodiment) Fig. 10 is a diagram showing a state immediately after casting of a rear body frame member 100 according to a modified example of the embodiment of the present invention. The rear body frame member 100 according to this modified example includes a header 300 and a deck member 301. Fig. 10 shows an example in which the rear body frame member 100 includes both the header 300 and the deck member 301, but it may also include only one of the header 300 and the deck member 301.

[0061] The header 300 and deck member 301 are connecting members that connect the upper part of the right rear suspension tower section 110 and the upper part of the left rear suspension tower section 120, respectively. The deck member 301 is located lower than the header 300 and relatively close to the connecting section 130, so it can be called a lower connecting member. The deck member 301 is integrally molded with the upper part of the right rear suspension tower section 110 and the upper part of the left rear suspension tower section 120.

[0062] The header 300 can be called an upper connecting member because it is relatively far from the connecting portion 130. The left and right sides of the header 300 are integrally molded with the upper part of the right rear suspension tower portion 110 and the upper part of the left rear suspension tower portion 120, respectively. By integrally molding the header 300 and the deck member 301 with the right rear suspension tower portion 110 and the left rear suspension tower portion 120, the number of parts can be reduced. Furthermore, by providing the header 300 and the deck member 301, the rigidity of the rear body frame member 100 can be improved.

[0063] Furthermore, in this modified example, the header 300 is spaced apart from the upper part of the right rear suspension tower section 110 and the upper part of the left rear suspension tower section 120 in a direction parallel to the extension direction of the ribs 116a to 116e and 117a to 117d, and is positioned so that the header 300 overlaps with the upper part of the right rear suspension tower section 110 and the upper part of the left rear suspension tower section 120 in a plan view immediately after casting. This makes it possible to reduce the projection area of ​​the rear body frame member 100 having the header 300 during casting.

[0064] (Effects of the embodiment) As described above, according to this embodiment, the right rear suspension tower section 110 and the left rear suspension tower section 120 are integrally molded by casting while being connected by the connecting section 130, thereby reducing the number of parts in the rear body frame member 100.

[0065] By integrally molding ribs 116a-116e, 117a-117d, 126a-126e, 127a-127d, 130a, 131a, 140 that protrude forward or rearward on body frame member 100, body frame member 100 can be made to have high rigidity against the input of impact loads from behind, for example.

[0066] When this body frame member 100 is cast, the ribs 116a to 116e, 117a to 117d, 126a to 126e, 127a to 127d, 130a, 131a, 140 are in a position where they protrude upward or downward, the upper wall portion 114a and the lower wall portion 114b of the right rear connection portion 114 are in a position where they extend upward, and the dimension of the projection surface of the body frame member 100 in direction A2 perpendicular to the vehicle width direction is shortened.This makes it possible to easily cast the body frame member 100 while improving its rigidity against input loads during a collision.

[0067] The above-described embodiments are merely examples in all respects and should not be construed as limiting. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0068] As described above, the present disclosure can be used, for example, in rear body frame members of automobiles. [Explanation of symbols]

[0069] 100 Rear body frame member 110 Right rear suspension tower 114 Right rear connection part (concave part) 114a Upper wall 114b Lower wall part 116a First right inner rib 117a First right outer rib 120 Left rear suspension tower 130 Connection section 200, 201 Molds 300 Header (connecting member) 301 Deck member (connecting member) A. Rear body structure

Claims

1. A method for manufacturing a rear vehicle body frame member in which a rear suspension tower section on one side in a vehicle width direction and a rear suspension tower section on the other side in the vehicle width direction are connected by a connecting section, and in which at least one rib that protrudes forward or rearward of the vehicle when assembled to the vehicle is integrally molded, Prepare a mold with the dividing direction set to the vertical direction, A manufacturing method for a rear body frame member, in which the rear body frame member is cast using the mold in a state where it is rotated when viewed from the side of the vehicle so that the rib protrudes upward or downward and the dimension of the projection surface from above in a direction perpendicular to the vehicle width direction is shorter than the dimension of the projection surface in a plan view of the vehicle in a direction perpendicular to the vehicle width direction.

2. 2. The method for manufacturing a rear vehicle body frame member according to claim 1, A manufacturing method for a rear body frame member, wherein the rib is molded in a state inclined with respect to the longitudinal direction of the vehicle.

3. 2. The method for manufacturing a rear vehicle body frame member according to claim 1, A method for manufacturing a rear body frame member, wherein the rib is continuous from at least one of the rear suspension tower portion on one side in the vehicle width direction and the rear suspension tower portion on the other side in the vehicle width direction to the connecting portion.

4. 2. The method for manufacturing a rear vehicle body frame member according to claim 1, A method for manufacturing a rear body frame member, which integrally molds a connecting member that connects the upper part of the rear suspension tower section on one side in the vehicle width direction and the upper part of the rear suspension tower section on the other side in the vehicle width direction.

5. 5. The method for manufacturing a rear vehicle body frame member according to claim 4, A method for manufacturing a rear body frame member, in which the connecting member is integrally molded away from the upper part of the rear suspension tower section on one side of the vehicle width direction and the upper part of the rear suspension tower section on the other side of the vehicle width direction in a direction parallel to the extension direction of the rib.

6. 2. The method for manufacturing a rear vehicle body frame member according to claim 1, the rib includes an inner rib integrally molded on an inner side of the rear suspension tower portion and an outer rib integrally molded on an outer side of the rear suspension tower portion, A method for manufacturing a rear body frame member, wherein the rear body frame member is cast in an orientation in which the inner rib and the outer rib protrude upward or downward.

7. A rear body structure in which a rear suspension tower section on one side in a vehicle width direction and a rear suspension tower section on the other side in the vehicle width direction are connected by a connecting section, and at least one rib protruding forward or rearward of the vehicle is integrally molded, a recessed portion that is open to the front of the vehicle and recessed to the rear of the vehicle; The upper and lower wall portions of the recessed portion extend in the same direction as the rib.

8. The rear vehicle body structure according to claim 7, A rear vehicle body structure in which a front end portion of a rear frame extending in the vehicle longitudinal direction is connected to the recessed portion.

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