Rocker beam outer member, door ring structure, and method for manufacturing door ring structure

Abstract

A sill beam outer member (30, 30A, 30B) is provided with a top plate (31), ridge parts (32, 33), vertical walls (34, 35), and flanges (36, 37). At least one of the vertical walls (34, 35) includes one or more ribs (381). The one or more stiffeners (381) extend in the longitudinal direction of the sill outer members (30, 30A, 30B). In a cross section of the sill outer member (30, 30A, 30B), when a straight line connecting an end portion of at least one vertical wall (34, 35) on a top plate (31) side and an end portion of at least one vertical wall (34, 35) on a flange (36, 37) side is taken as a reference line (R1), at least one reinforcing rib (381) protrudes from the reference line (R1) to an inner side or an outer side of the sill outer member (30, 30A, 30B). The sum of the depths of the one or more reinforcing ribs (381) with respect to the reference line (R1) is 4.0 times or more of the plate thickness of the top plate (31).

Description

Technical Field

[0001] This disclosure relates to the outer components of door sill beams for automobiles. Additionally, this disclosure relates to door ring structures for automobiles and methods of manufacturing them. Background Technology

[0002] A car's body consists of multiple skeletal components. Examples of these skeletal components include crash beams, A-pillars (front pillars), B-pillars (middle pillars), C-pillars (rear pillars), side beams, and sill beams (lower side beams).

[0003] For example, Patent Document 1 discloses a side frame structure for the door opening of a car body. This side frame structure includes, for example, an A-pillar (upper outer member of the A-pillar), a hinge pillar (lower outer member of the A-pillar), a B-pillar (outer member of the B-pillar), and a sill beam outer member. Patent Document 1 describes manufacturing the side frame structure by stamping from a composite blank formed by joining multiple blanks.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2021-528248 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In recent years, high-strength materials have become increasingly used in automotive frame components to ensure high crashworthiness. Frame components are, for example, made of steel with a tensile strength of 980 MPa or higher. However, as steel increases in strength, its ductility decreases, leading to a problem where the higher the strength of the steel used to form the frame component, the more prone the frame component is to fracture during a car crash.

[0009] For example, in the vehicle body side structure frame of Patent Document 1, during a side collision, the load from the side of the vehicle body acts on the outer member of the sill beam. Therefore, the outer member of the sill beam deforms, and tensile strain concentrates locally. When the outer member of the sill beam is made of a high-strength material with low ductility, it is prone to fracture at the strain concentration point. In the event of fracture, the energy absorption performance of the outer member is significantly reduced, thus failing to utilize the advantages of the high-strength material.

[0010] The subject of this disclosure is to provide a door sill beam outer component that is not easily broken in the event of a car collision.

[0011] Solution for solving the problem

[0012] The disclosed sill beam outer member for automobiles comprises: a top plate; two longitudinal walls disposed on both sides of the top plate and connected to the top plate via ridge portions; and a flange connected to each of the two longitudinal walls on the side opposite to the side where the top plate is located. The sill beam outer member is formed of a steel plate having a tensile strength of 980 MPa or more. At least one of the two longitudinal walls includes one or more first reinforcing ribs. The one or more first reinforcing ribs extend along the long side direction of the sill beam outer member. In the cross-section of the sill beam outer member, with a straight line connecting the end of the at least one longitudinal wall on the top plate side and the end on the flange side as a reference line, the one or more first reinforcing ribs protrude from the reference line toward the inner or outer side of the sill beam outer member. The total depth of the one or more first reinforcing ribs relative to the reference line is at least 4.0 times the thickness of the top plate.

[0013] The effects of the invention

[0014] According to this disclosure, the outer components of the door sill beam are less likely to break during a car collision. Attached Figure Description

[0015] Figure 1 This is a side view of the door ring structure according to the first embodiment.

[0016] Figure 2A yes Figure 1 Sectional view II-II of the door ring structure including the sill beam outer component.

[0017] Figure 2B yes Figure 2A The enlarged view of the outer components of the threshold beam is shown.

[0018] Figure 3A This is a schematic diagram illustrating the manufacturing method of the door ring structure according to the first embodiment.

[0019] Figure 3B This is a schematic diagram illustrating the manufacturing method of the door ring structure according to the first embodiment.

[0020] Figure 3C This is a schematic diagram illustrating the manufacturing method of the door ring structure according to the first embodiment.

[0021] Figure 3D This is a schematic diagram illustrating the manufacturing method of the door ring structure according to the first embodiment.

[0022] Figure 3E This is a schematic diagram illustrating the manufacturing method of the door ring structure according to the first embodiment.

[0023] Figure 4 This is a cross-sectional view of the outer member of the threshold beam in the second embodiment.

[0024] Figure 5 This is a cross-sectional view of the outer member of the threshold beam in the third embodiment.

[0025] Figure 6A This is a schematic diagram illustrating a manufacturing method different from the manufacturing method of the door ring structure in the first embodiment.

[0026] Figure 6B This is a schematic diagram illustrating a manufacturing method different from the manufacturing method of the door ring structure in the first embodiment.

[0027] Figure 6C This is a schematic diagram illustrating a manufacturing method different from the manufacturing method of the door ring structure in the first embodiment.

[0028] Figure 7 This is a cross-sectional view of the outer member of the threshold beam in a modified embodiment of the above-described embodiment.

[0029] Figure 8 This is a cross-sectional view of the outer member of the threshold beam in another variation of the above embodiment.

[0030] Figure 9 This is a side view of a door ring structure of a modified embodiment of the above-described embodiment. Detailed Implementation

[0031] The sill beam outer member for automobiles according to the embodiment includes: a roof plate; two longitudinal walls disposed on both sides of the roof plate and connected to the roof plate via ridge portions; and a flange connected to the two longitudinal walls on the side opposite to the side where the roof plate is located. The sill beam outer member is formed of a steel plate having a tensile strength of 980 MPa or more. At least one of the two longitudinal walls includes one or more first reinforcing ribs. One or more first reinforcing ribs extend along the long side direction of the sill beam outer member. In the cross-section of the sill beam outer member, with a straight line connecting the end of the at least one longitudinal wall on the roof plate side and the end on the flange side as a reference line, one or more first reinforcing ribs protrude from the reference line toward the inside or outside of the sill beam outer member. The sum of the depths of the one or more first reinforcing ribs relative to the reference line is at least 4.0 times the thickness of the roof plate (first configuration).

[0032] When the sill beam outer member is assembled into the vehicle body, the top plate of the sill beam outer member is positioned outwards relative to the two longitudinal walls in the left-right direction of the vehicle body, with one longitudinal wall positioned below the other. When, for example, a pole-shaped impact object collides with the vehicle body from the side, the sill beam outer member deforms, and with this deformation, tensile stress and strain concentration occur locally in the sill beam outer member. Therefore, in the first configuration of the sill beam outer member, one or more first reinforcing ribs are formed in at least one longitudinal wall. Unlike typical reinforcing ribs provided in the frame members of a vehicle for the purpose of increasing rigidity, the first reinforcing ribs have sufficient depth. Specifically, the total depth of one or more first reinforcing ribs is at least 4.0 times the thickness of the top plate. This ensures the cross-sectional length of the sill beam outer member, thus easily dispersing strain at and near the deformed area when, for example, the sill beam outer member deforms due to a side pole impact. As a result, even when the outer sill beam is made of a high-strength material with a tensile strength of 980 MPa or more, it is not easy for the outer sill beam to break during a car collision.

[0033] In the first configuration of the threshold beam outer member, it is also possible that each of the two longitudinal walls includes one or more first reinforcing ribs (second configuration).

[0034] In the second configuration of the sill beam outer member, one or more first reinforcing ribs are formed on each of the two longitudinal walls. This further extends the cross-sectional length of the sill beam outer member, thus making it easier to disperse strain at and near the deformed area when deformation occurs due to a side pillar impact. Therefore, the sill beam outer member is less prone to fracture during a car collision.

[0035] In the first or second configuration of the sill beam outer member, the top plate may include a second reinforcing rib. The second reinforcing rib has a shape that is recessed inward toward the inner side of the sill beam outer member and extends along the long side of the sill beam outer member (third configuration).

[0036] In the third component of the sill beam outer member, the presence of a second reinforcing rib in the top plate further extends its cross-sectional length. This allows for further dispersion of strain in the deformed areas and surrounding regions of the sill beam outer member during a vehicle collision, thus reducing the likelihood of fracture.

[0037] In the third component of the threshold beam outer member, the second reinforcing rib may have a depth of more than 5.0 times the thickness of the top plate (fourth component).

[0038] In the fourth component of the sill beam outer member, a relatively deep second reinforcing rib is located in the top plate. Specifically, the depth of the second reinforcing rib is more than 5.0 times the thickness of the top plate. This further extends the cross-sectional length of the sill beam outer member, thus making it easier to disperse strain in and around the deformed area of ​​the sill beam outer member during a vehicle collision. Therefore, it is easier to suppress fracture of the sill beam outer member.

[0039] In the third or fourth configuration of the sill beam outer member, it is also possible that, in the cross-section of the sill beam outer member with the two longitudinal walls positioned vertically, the center of the bottom of the second reinforcing rib is positioned below the center of the top plate (fifth configuration).

[0040] In a side impact collision, if the sill beam outer member rotates downwards towards the vehicle body, the intrusion of the sill beam outer member onto the lower side of the vehicle body increases, potentially affecting components such as the battery located on the lower side of the vehicle body. In contrast, in the fifth configuration, the center of the bottom of the second reinforcing rib is positioned below the center of the roof panel. This increases the stiffness of the lower part of the sill beam outer member, effectively suppressing its downward rotation during a side impact.

[0041] The door ring structure for automobiles in the embodiment includes a sill beam outer member (sixth configuration) of any one of the first to fifth configurations.

[0042] In the manufacturing method of the embodiment, a door ring structure of the sixth configuration is manufactured. This manufacturing method includes: a preparation step in which a blank having a ring shape when viewed from above is prepared; a heating step in which the blank is heated to above the austenitic phase transformation completion temperature; and a forming step in which the heated blank is formed into a door ring structure using a die and then quenched. The die includes a punch, a die, and a pressure plate. The portion of the punch used to form the outer member of the door sill beam includes a punch body and a buffer member opposite to the pressure plate and configured to be housed within the punch body. In the forming step, the portion of the blank formed into a top plate is clamped by the pressure plate and the buffer member, and then, while the blank is clamped by the pressure plate and the buffer member, the blank is stamped using the punch body and the die (seventh configuration).

[0043] In another embodiment of the manufacturing method, a door ring structure of the sixth configuration is manufactured. This manufacturing method includes: a preparation step in which a blank having a ring shape when viewed from above is prepared; a heating step in which the blank is heated to above the austenitic transformation completion temperature; and a forming step in which the heated blank is formed into a door ring structure using a die and then quenched. The die includes a punch, a die, and a pressure plate. In the forming step, the portion of the blank formed into a top plate is held by the pressure plate and the punch, and the blank is stamped by the punch and the die to form a longitudinal wall and a flange (the eighth configuration).

[0044] To simplify the manufacturing process of door ring structures, it is considered to integrate multiple skeleton components, including the outer sill beam, from the blank stage. However, when forming relatively large door ring structures from annular blanks, dimensional accuracy can sometimes be compromised. This is particularly true when door ring structures are manufactured using hot stamping, where dimensional accuracy may deteriorate. More specifically, in hot stamping, annular blanks are heated above the austenitic transformation completion temperature, then formed into door ring structures using a die and quenched. The door ring structure dissipates heat through contact with the die (rapid cooling), and its microstructure transforms from austenitic to martensite. If the cooling rate is sufficiently ensured, a single-phase martensite microstructure can be obtained; however, if the cooling rate is insufficient, ferrite precipitates in addition to martensite.

[0045] In the manufacture of hot-stamped door ring structures, stress is released during the austenitic-to-martensite phase transformation, making springback less likely. However, for example, in cases where insufficient cooling rates in a localized area of ​​the door ring structure lead to ferrite precipitation, stress may not be fully released at that location, potentially causing springback. Because door ring structures are large and annular, even slight springback in a single area can significantly impact the overall dimensional accuracy of the door ring structure. For instance, residual stress on the top plate of the sill beam outer member can cause springback in the sill beam outer member, sometimes leading to torsion within the door ring structure.

[0046] In the manufacturing method of configuration 7, when forming the annular blank into a door knocker structure, at the position of the outer member of the door sill beam, the portion of the blank that becomes the top plate of the outer member of the door sill beam is first clamped by a pressure plate and a buffer. That is, from the initial stage of forming, the top plate of the outer member of the door sill beam is in contact with the pressure plate and the buffer, ensuring a rapid cooling rate. Therefore, the microstructure of the top plate of the outer member of the door sill beam easily becomes a single-phase martensitic structure, and stress is easily released. As a result, the springback of the outer member of the door sill beam can be reduced, and the torsion of the door knocker structure can be suppressed. Therefore, the dimensional accuracy of the door knocker structure can be improved according to the manufacturing method of configuration 7.

[0047] In the manufacturing methods of the seventh and eighth configurations, the door ring structure, including the sill beam outer member, is manufactured by hot stamping. Therefore, the sill beam outer member can be made to have high strength (tensile strength: 980 MPa or more), and a relatively deep first reinforcing rib can be formed in at least one longitudinal wall. For example, even in cases where it is difficult to form the first reinforcing rib by simple bending, a relatively deep first reinforcing rib can be formed in one or both longitudinal walls of the sill beam outer member by using hot stamping, while suppressing cracking.

[0048] The following is a reference to the appendix. Figure 1 The embodiments of this disclosure will be described below. In each figure, the same or equivalent structures are labeled with the same reference numerals, and the same descriptions are not repeated.

[0049] <First Implementation>

[0050] [Door ring structure]

[0051] Figure 1 This is a diagram showing a schematic structure of the door ring structure 100 according to this embodiment. The door ring structure 100 is used in automobiles. The door ring structure 100 is assembled into the body of the automobile. Figure 1 The diagram shows the door ring structure 100 as viewed from the side (left) of the vehicle when assembled to the vehicle body. Hereinafter, this embodiment will be described using the front, rear, left, and right sides of the vehicle body with the door ring structure 100 assembled to the vehicle body as the front, rear, left, and right sides of the door ring structure 100 and the frame members included in the door ring structure 100.

[0052] Reference Figure 1 The door ring structure 100 has a ring shape when viewed from the side. The door ring structure 100 extends from the outside of the vehicle body in the left-right direction. Figure 1 Other door ring structures not shown are joined. That is, door ring structure 100 is the outer door ring structure. Door ring structure 100 includes upper outer member 11 of A-pillar, lower outer member 12 of A-pillar, outer member 20 of B-pillar, and outer member 30 of door sill beam.

[0053] The lower outer member 12 of the A-pillar is positioned below and in front of the upper outer member 11 of the A-pillar and engages with the upper outer member 11. The outer member 20 of the B-pillar engages with the rear portion of the upper outer member 11 of the A-pillar and extends downward from the upper outer member 11. The outer member 30 of the sill beam engages with the lower ends of the lower outer member 12 of the A-pillar and the outer member 20 of the B-pillar and extends from the lower outer member 12 of the A-pillar toward the outer member 20 of the B-pillar. That is, the outer member 30 of the sill beam has an elongated shape and extends in the longitudinal direction when assembled into the body of the vehicle.

[0054] The size of the ring-shaped door knocker structure 100 when viewed from the side is, for example, 1.0m or more. The size of the door knocker structure 100 can be, for example, 4.0m or less. The size of the door knocker structure 100 refers to the length of the line segment connecting the two furthest points on the outer periphery of the door knocker structure 100 when viewed vertically with the door knocker structure 100 placed on a horizontal plane.

[0055] Figure 2A yes Figure 1 Sectional view II-II. Figure 2A This indicates the cross-section of the threshold beam outer component 30 included in the door ring structure 100.

[0056] Reference Figure 2A The sill beam outer member 30 is formed of a steel plate with a tensile strength of 980 MPa or more. The sill beam outer member 30 may have a tensile strength of 1470 MPa or more, and more preferably 1760 MPa or more. The tensile strength of the sill beam outer member 30 can be obtained by taking a test piece from a relatively flat portion of the sill beam outer member 30 and performing a tensile test on the test piece according to JIS Z 2241:2022. When assembled into the vehicle body, the sill beam outer member 30 forms a closed section together with the sill beam inner member 40. An energy-absorbing member 50 is disposed within the space formed by the sill beam outer member 30 and the sill beam inner member 40. The energy-absorbing member 50 is, for example, an extruded aluminum alloy.

[0057] The sill beam outer member 30 has a roughly cap shape in cross-sectional view. The sill beam outer member 30 includes a top plate 31, ridge portions 32 and 33, longitudinal walls 34 and 35, and flanges 36 and 37.

[0058] The top plate 31 extends along the long side of the sill beam outer member 30. That is, the top plate 31 extends substantially along the longitudinal direction of the vehicle body. Longitudinal walls 34 and 35 are disposed on both sides of the top plate 31. Flanges 36 and 37 are connected to the longitudinal walls 34 and 35 on the side opposite to the side where the top plate 31 is located. Ridge portions 32 and 33, longitudinal walls 34 and 35, and flanges 36 and 37 extend along the long side of the sill beam outer member 30 in the same manner as the top plate 31.

[0059] The longitudinal wall 34 is connected to the top plate 31 via a ridge portion 32. The ridge portion 32 forms a corner between the top plate 31 and the longitudinal wall 34. The ridge portion 32, viewed from the cross-sectional perspective of the outer member 30 of the sill beam, has a curved shape protruding outwards from the outer member 30 of the sill beam. A flange 36 is continuous with the longitudinal wall 34 on the opposite side of the ridge portion 32. The flange 36 protrudes outwards from the longitudinal wall 34 towards the outer member 30 of the sill beam.

[0060] With the sill beam outer member 30 assembled to the vehicle body, the longitudinal wall 35 is positioned below the longitudinal wall 34. The longitudinal wall 35 is connected to the roof plate 31 via a ridge portion 33. The ridge portion 33 forms a corner between the roof plate 31 and the longitudinal wall 35. The ridge portion 33 has a curved shape protruding outward from the sill beam outer member 30 in a cross-sectional view. The flange 37 is continuous with the longitudinal wall 35 on the opposite side of the ridge portion 33. The flange 37 protrudes outward from the longitudinal wall 35 towards the outer side of the sill beam outer member 30.

[0061] A longitudinal wall 34 includes one or more reinforcing ribs 381 extending along the long side of the outer member 30 of the threshold beam. In this embodiment, two reinforcing ribs 381 are provided adjacent to each other in the longitudinal wall 34. The two reinforcing ribs 381 are formed in a stepped shape in the longitudinal wall 34.

[0062] exist Figure 2A In the example, in the cross-section of the outer member 30 of the sill beam, a reinforcing rib 381 protrudes from the reference line R1 toward the inner side of the outer member 30. In the cross-section of the outer member 30 of the sill beam, another reinforcing rib 381 protrudes from the reference line R1 toward the outer side of the outer member 30. The reference line R1 is an imaginary straight line connecting the end 341 on the top plate 31 side of the longitudinal wall 34 to the end 342 on the flange 36 side of the longitudinal wall 34. The end 341 is the rounded end of the ridge portion 32 on the longitudinal wall 34 side of the outer surface of the outer member 30 of the sill beam. The end 342 is the rounded end of the curved portion of the flange 36 adjacent to the longitudinal wall 34 on the outer surface of the outer member 30 of the sill beam.

[0063] In this embodiment, the portion of the longitudinal wall 34 between one reinforcing rib 381 and the ridge portion 32 is called a flat portion 343. A flat portion 344 is also provided in the portion of the longitudinal wall 34 between another reinforcing rib 381 and the flange 36. The flat portions 343 and 344 are portions disposed on the reference line R1 and substantially extending along the reference line R1 from a cross-sectional view of the outer member 30 of the sill beam.

[0064] All reinforcing ribs 381 in the longitudinal wall 34 have a depth D1. The depths D1 of these reinforcing ribs 381 may be the same or different. In the longitudinal wall 34, the sum of the depths D1 of the reinforcing ribs 381 relative to the reference line R1 is at least 4.0 times the thickness t of the top plate 31. Alternatively, the sum of the depths D1 of the reinforcing ribs 381 relative to the reference line R1 may be less than 15.0 times the thickness t of the top plate 31. When multiple reinforcing ribs 381 are provided in the longitudinal wall 34 as in this embodiment, the sum of the depths D1 of the reinforcing ribs 381 is obtained by adding the depths D1 of all the reinforcing ribs 381. On the other hand, when only one reinforcing rib 381 is provided in the longitudinal wall 34, the depth D1 of that reinforcing rib 381 is itself the sum of the depths D1. The depth D1 of the reinforcing rib 381 is the shortest distance in the cross-section of the outer member 30 of the sill beam from the reference line R1 to a straight line L1 parallel to the reference line R1 and connecting to the top of the reinforcing rib 381 protruding towards the inner or outer side of the outer member 30 of the sill beam. The straight line L1 connects to the top of the reinforcing rib 381 on the outer surface of the outer member 30 of the sill beam. The depth D1 of each reinforcing rib 381 may be constant along the entire length of the reinforcing rib 381 extending along the long side direction of the outer member 30 of the sill beam, or it may not be constant. The reinforcing rib 381 may extend integrally along the long side direction of the outer member 30 of the sill beam throughout the longitudinal wall 34, or it may be provided only in a part of the longitudinal wall 34. In the outer member 30 of the sill beam, the length (long side direction) of the area where the sum of the depths D1 of the reinforcing ribs 381 is more than 4.0 times the thickness t of the top plate 31 is preferably 600 mm or more, for example.

[0065] Figure 2B It is Figure 2A A magnified view of the longitudinal wall 34 and its vicinity in the cross-section of the outer member 30 of the threshold beam. (Refer to...) Figure 2B From a cross-sectional view of the sill beam outer member 30, it is preferable that each reinforcing rib 381 does not have a portion extending substantially parallel to the reference line R1. In other words, each reinforcing rib 381 is preferably configured such that its top, i.e., the portion contacting the straight line L1, is not flat. From a cross-sectional view of the sill beam outer member 30, each reinforcing rib 381 may, for example, have a triangular shape or a curved shape protruding inward or outward from the sill beam outer member 30.

[0066] When multiple reinforcing ribs 381 are provided in the longitudinal wall 34 as in this embodiment, the side of the reinforcing rib 381 closest to the top plate 31 forms an angle θ with the reference line R1 from the cross-sectional view of the sill beam outer member 30. When a single reinforcing rib 381 is provided in the longitudinal wall 34, the side of this reinforcing rib 381 forms an angle θ with the reference line R1 from the cross-sectional view of the sill beam outer member 30. The angle θ can be, for example, 120° or more. Here, the side is the portion of the surface of the reinforcing rib 381 that protrudes to the outside or inside of the sill beam outer member 30, located between the reference line R1 and the straight line L1. The angle θ is preferably 135° or more, more preferably 150° or more. The angle θ can also be 170° or less. When more than half of the side of the reinforcing rib 381 is a straight portion, the angle θ is the angle formed by this straight portion and the reference line R1. When the side surface of the reinforcing rib 381 is generally curved, the angle θ is the angle between the tangent to the reference line R1 at the midpoint between the reference line R1 and the straight line L1 on the side surface of the reinforcing rib 381 and the reference line R1.

[0067] return Figure 2A In this embodiment, a plurality of reinforcing ribs 381 are provided in one longitudinal wall 34, but no reinforcing ribs 381 are provided in the other longitudinal wall 35. However, it is also possible that the longitudinal wall 34 has no reinforcing ribs 381, while the longitudinal wall 35 has one or more reinforcing ribs 381. Alternatively, both the longitudinal walls 34 and 35 may have one or more reinforcing ribs 381. In the cross-section of the outer member 30 of the threshold beam, the longitudinal walls 34 and 35 may also be asymmetrical with respect to the width centerline of the top plate 31. For example, the slopes of the longitudinal walls 34 and 35 with respect to the top plate 31 may also be different. When both the longitudinal walls 34 and 35 have at least one reinforcing rib 381, the position, shape, and depth D1 of the reinforcing ribs 381 in the longitudinal walls 34 and 35 may also be different. In addition, the number of reinforcing ribs 381 in the longitudinal wall 35 may also be different from the number of reinforcing ribs 381 in the longitudinal wall 34. The width centerline of the top plate 31 refers to the straight line passing through the width center C0 and perpendicular to the straight line L0 in the cross-section of the outer member 30 of the sill beam, when the point located at the midpoint of the intersections B1 and B2 of the top plate 31 and the intersection of the top plate 31 and the other edge portion 33 is set as the width center C0 of the top plate 31. The intersections B1 and B2 are the rounded ends of the edges 32 and 33 on the top plate 31 side of the outer surface of the outer member 30 of the sill beam.

[0068] Reference Figure 2AIn this embodiment, the top plate 31 also includes a reinforcing rib 382 extending along the long side of the sill beam outer member 30. The reinforcing rib 382 has a shape that is recessed inward toward the sill beam outer member 30. In the cross-section of the sill beam outer member 30, the width of the opening of the reinforcing rib 382 is less than the width W of the top plate 31 (the straight-line distance between the junctions B1 and B2). Therefore, when viewed in cross-section of the sill beam outer member 30, the top plate 31 includes flat portions 311 and 312 on both sides of the reinforcing rib 382. The flat portions 311 and 312 are portions disposed on and substantially extending along the straight line L0 in the cross-sectional view of the sill beam outer member 30. The width W of the top plate 31 can be, for example, more than 30 mm and less than 300 mm.

[0069] The reinforcing rib 382 is preferably disposed on the top plate 31 in a manner that does not interfere with the energy-absorbing component 50. Figure 2A In the example, the stiffener 382 is positioned downwards relative to the width center C0 of the top plate 31.

[0070] More specifically, in the cross-section of the sill beam outer member 30 assembled to the vehicle body, i.e., with the longitudinal walls 34 and 35 positioned vertically, the bottom center (bottom center) C1 of the reinforcing rib 382 is positioned lower than the width center C0 of the top plate 31. Preferably, the bottom center C1 of the reinforcing rib 382 is offset downward from the width W of the top plate 31 by more than 10% relative to the width center C0 of the top plate 31. The bottom center C1 of the reinforcing rib 382 is the vertical center point of the portion of the straight line L2 that connects to the bottom of the reinforcing rib 382. The straight line L2 is parallel to the straight line L0 connecting the junctions B1 and B2 and connects to the bottom of the reinforcing rib 381 on the outer surface of the sill beam outer member 30. In the cross section of the outer member 30 of the threshold beam, when the straight line L2 is in contact with the bottom point of the reinforcing rib 382 on the outer surface of the outer member 30 of the threshold beam, the contact point between the bottom of the reinforcing rib 382 and the straight line L2 becomes the bottom center C1 of the reinforcing rib 382.

[0071] In this embodiment, when viewed in cross-section of the outer member 30 of the sill beam, the stiffener 382 has a substantially symmetrical shape with respect to the bottom centerline of the stiffener 382 (a straight line passing through the bottom center C1 and perpendicular to the straight line L0). However, the stiffener 382 may not necessarily have a symmetrical shape with respect to the bottom centerline of the stiffener 382.

[0072] The reinforcing rib 382 can have a depth D2 that is at least 5.0 times the thickness t of the top plate 31. The depth D2 of the reinforcing rib 382 can also be less than 15.0 times the thickness t of the top plate 31. The depth D2 of the reinforcing rib 382 is the shortest distance between straight lines L0 and L2 in the cross-section of the outer member 30 of the sill beam. The thickness t of the top plate 31 is, for example, the thickness measured at the locations of the flat portions 311 and 312. The thickness t is, for example, 0.8 mm or more. The thickness t can also be less than 2.0 mm. The depth D2 can be constant along the entire length of the reinforcing rib 382 extending along the long side of the outer member 30 of the sill beam, but it can also be variable. For example, at both ends of the reinforcing rib 382 along the long side, the depth D2 can be smaller compared to other portions.

[0073] [Manufacturing method of door knocker structure]

[0074] The following is for reference Figures 3A-3E The manufacturing method of the door knocker structure 100 will be described. The manufacturing method of the door knocker structure 100 in this embodiment includes a preparation process of the blank 60, a heating process of the blank 60, and a forming process of the blank 60.

[0075] (Preparation process)

[0076] like Figure 3A As shown, in the preparation process, a blank 60 with an annular shape when viewed from above is prepared. The blank 60 has the shape after unfolding the annular door ring structure 100. In the example of this embodiment, the blank 60 includes a plurality of steel plates 61, 62, 63, and 64. The steel plates 61, 62, 63, and 64 are arranged and joined in an annular shape when viewed from above. Each steel plate 61, 62, 63, and 64 is joined to adjacent steel plates by, for example, laser welding. Alternatively, each steel plate 61, 62, 63, and 64 may also be joined to adjacent steel plates by, for example, spot welding. The joining method of the steel plates 61, 62, 63, and 64 is not particularly limited.

[0077] exist Figure 3A In the example, the part in blank 60 that becomes the upper outer component 11 of the A-pillar ( Figure 1 The blank 60 is equipped with steel plate 61. Additionally, the portion of the blank 60 that forms the lower outer component 12 of the A-pillar, the outer component 20 of the B-pillar, and the outer component 30 of the sill beam ( Figure 1 The steel plates 61, 62, 63, and 64 are provided. The thickness of steel plates 61, 62, 63, and 64 can be the same as or different from the other steel plates. The tensile strength of steel plates 61, 62, 63, and 64 in the blank state can be the same as or different from the other steel plates. Steel plates 61, 62, 63, and 64 can be coated steel plates with aluminum or zinc coatings, or they can be bare materials without coatings.

[0078] (Heating process)

[0079] The prepared blank 60 is formed into a door ring structure 100 by hot stamping (hot pressing). Figure 1 During hot stamping, the blank 60 undergoes a heating process. (Refer to...) Figure 3B In the heating process, for example, the billet 60 is heated using a heating furnace 70. The billet 60 is heated to the austenite phase transformation completion temperature (A). c3 (Point) or above. The billet 60 is, for example, heated to 900°C or above. Thus, the steel plates 61, 62, 63, and 64 contained in the billet 60 (point) Figure 3A The microstructure of the austenitic phase is transformed into the austenitic phase.

[0080] (Forming process)

[0081] Reference Figure 3C In the forming process, mold 80 is used to form the heated blank 60 into a ring-shaped door knocker structure 100 when viewed from above. Figure 1 The billet 60, heated through the heating process, is then removed from the heating furnace 70 (and quenched). Figure 3B The blank is removed and conveyed to die 80. Die 80 is mounted on a known stamping device. Die 80 includes punch 81, die 82 and pressure plate 83.

[0082] First, the specific structure of the mold 80 used in the forming process will be explained. Figure 3C It is the outer component 30 of the threshold beam in mold 80. Figure 1 and Figure 2A The cross-sectional view of the corresponding part. Figure 3C The image shows the forming process in mold 80. Figure 1 and Figure 2A The cross-section of the top plate 31 of the outer member 30 of the threshold beam shown, where the reinforcing rib 382 is located and the reinforcing rib 381 of the longitudinal wall 34 is located.

[0083] like Figure 3C As shown, the portion of the punch 81 used to form the outer member 30 of the sill beam includes a punch body 811 and a buffer 812 configured to be received within the punch body 811. The punch body 811 includes reinforcing ribs 381 on its sides for forming reinforcing ribs 381 in the longitudinal wall 34. Figure 2A and Figure 2BThe punch body 811 has a stepped portion 811a. Additionally, the punch body 811 has a concave receiving portion 811b on its top surface. The buffer member 812 is supported on the bottom surface of the receiving portion 811b via an elastic member 84. The elastic member 84 is a member capable of extending and retracting in the punching direction. For example, a gas spring can be used as the elastic member 84. When the elastic member 84 is in an extended state, the top surface of the buffer member 812 protrudes from the top surface of the punch body 811. When the elastic member 84 is in a shortened state, the buffer member 812 is received in the receiving portion 811b of the punch body 811 in such a way that the top surface of the buffer member 812 is substantially flush with the top surface of the punch body 811.

[0084] The die 82 is arranged opposite the punch 81 in the stamping direction. On each side of the die 82, a step 821 is provided corresponding to the step 811a on each side of the punch body 811. The pressure plate 83 is arranged opposite the buffer member 812 in the stamping direction. Figure 3C In the example shown, the pressure plate 83 is supported on the die 82 via an elastic member 85. The elastic member 85 is a member that can extend and retract in the stamping direction. For example, a pneumatic spring can be used as the elastic member 85.

[0085] A reinforcing rib 382 for forming a reinforcing rib on the top plate 31 is formed on the surface of the buffer 812 of the punch 81 opposite to the pressure plate 83. Figure 2A The recess 812a of the pressure plate 83. On the surface of the pressure plate 83 opposite to the buffer member 812, a protrusion 831 is formed corresponding to the recess 812a of the buffer member 812.

[0086] Next, the stamping forming of the blank 60 using die 80 will be explained. (Continue referring to...) Figure 3C Before the stamping process begins, the elastic member 84 extends, and the buffer 812 of the punch 81 protrudes from the punch body 811 toward the pressure plate 83. Additionally, the elastic member 85 extends, and at least one surface of the pressure plate 83 opposite to the buffer 812 is positioned relative to the die 82 on the punch 81 side. The blank 60, which is heated during the heating process, is positioned between the punch 81 and the die 82, and between the punch 81 and the pressure plate 83. The blank 60 may, for example, be placed on the buffer 812.

[0087] Reference Figure 3D After the blank 60 is positioned between the punch 81 and the die 82 and between the punch 81 and the pressure plate 83, the die 82 and the pressure plate 83 are moved relative to the punch 81 in the stamping direction, bringing the die 82 and the pressure plate 83 closer to the punch 81. Thus, the blank 60 is first held by the pressure plate 83 and the buffer 812 of the punch 81. More specifically, the top plate 31 in the blank 60, which is formed as the sill beam outer member 30, Figure 2AThe portion is clamped by the pressure plate 83 and the buffer 812 to form a reinforcing rib 382.

[0088] After that, as Figure 3E As shown, with the blank 60 held in place by the pressure plate 83 and the buffer 812, the blank 60 is stamped by the punch body 811 and the die 82. More specifically, after the blank 60 is held in place by the pressure plate 83 and the buffer 812, the die 82 and the pressure plate 83 are brought closer to the punch 81 in the stamping direction while maintaining this state. As a result, the elastic member 84 contracts and the buffer 812 is received in the receiving portion 811b of the punch body 811, and then the elastic member 85 contracts and the die 82 moves relative to the pressure plate 83 toward the punch 81. Then, the blank 60 is stamped by the punch body 811 and the die 82, forming a shape along the forming surfaces of the punch 81, the die 82, and the pressure plate 83. The blank 60 is held in a state between the punch 81 and the die 82 and between the punch 81 and the pressure plate 83. The blank 60 dissipates heat (rapid cooling) through the mold 80, and its microstructure transforms into martensite.

[0089] Although the illustration is omitted, the skeleton members 11, 12, and 20 in the door ring structure 100, other than the sill beam outer member 30, are also formed by the die 80, which includes a punch 81, a die 82, and a pressure plate 83. However, it is also possible that the buffer member 812 is not provided at the locations where the punch 81 forms the other skeleton members 11, 12, and 20. That is, for the parts of the die 80 where it is not necessary to form reinforcing ribs on the top plate, it is also possible to use a punch that is not divided into a punch body and a buffer member (a typical block punch) for forming.

[0090] [Effect]

[0091] In this embodiment, the sill beam outer member 30, when assembled into the vehicle body, forms a closed cross section together with the sill beam inner member 40. The sill beam outer member 30 is assembled into the vehicle body with the longitudinal wall 35 positioned below the longitudinal wall 34 and the top plate 31 facing outwards in the left-right direction. In the event of a side impact from a pole-shaped impact object, a load is applied to the sill beam outer member 30 from the top plate 31 side. When a portion of the sill beam outer member 30 is pressed inwards towards the vehicle body under the impact load and deforms, forming a ridge-like portion, tensile stress is generated and strain concentration occurs in this ridge-like portion. However, in this embodiment, by forming one or more reinforcing ribs 381 in the longitudinal wall 34, the cross-sectional length of the sill beam outer member 30 is ensured. In particular, the sum of the depths D1 of the one or more reinforcing ribs 381 in the longitudinal wall 34 is more than 4.0 times the plate thickness t of the top plate 31, thereby sufficiently extending the cross-sectional length of the sill beam outer member 30. Therefore, for example, when the sill beam outer member 30 deforms due to a side pillar impact, the strain tends to disperse along the length of the cross-section at and near the deformed area, reducing the strain in the angular portion. As a result, even if the tensile strength of the sill beam outer member 30 is 980 MPa or higher, it is less likely to fracture during a car collision.

[0092] When viewed in cross-section of the sill beam outer member 30, if the direction perpendicular to the straight line L0 connecting the junction B1 of the top plate 31 and the ridge portion 32 and the junction B2 of the top plate 31 and the ridge portion 33 is defined as the height direction, and the straight-line distance in the height direction from the flat surface of the flange 36 (outer side of the sill beam outer member 30) to the surface of the top plate 31 (outer side of the sill beam outer member 30) is defined as the height of the longitudinal wall 34, then each reinforcing rib 381 is preferably located at a height of 70% or less of the height of the longitudinal wall 34 as measured from the flange 36. This ensures the distance between the ridge portion 32 and the reinforcing rib 381. In this case, during a car collision, the ridge-shaped portion formed by the deformation of the sill beam outer member 30 is less likely to connect with the reinforcing rib 381, thus easily achieving the effect of ensuring the cross-sectional length based on the reinforcing rib 381. Similarly, when more than one reinforcing rib 381 is provided in the longitudinal wall 35, the reinforcing rib 381 is preferably located at a height of less than 70% of the height of the longitudinal wall 35 as measured from the flange 37. The height of the longitudinal wall 35 is the straight-line distance in the cross-section of the outer member 30 of the sill beam from the flat surface of the flange 37 (outer side of the outer member 30 of the sill beam) to the surface of the top plate 31 (outer side of the outer member 30 of the sill beam) in a direction perpendicular to the straight line L0.

[0093] In the sill beam outer member 30 of this embodiment, a reinforcing rib 382 is also provided in the top plate 31. Therefore, the cross-sectional length of the sill beam outer member 30 can be further extended. Consequently, in the event of a vehicle collision, the strain in and around the deformed portion of the sill beam outer member 30 can be further reduced. In particular, when the depth D2 of the reinforcing rib 382 is more than 5.0 times the thickness t of the top plate 31, the strain reduction effect is significant. Therefore, the sill beam outer member 30 is less likely to fracture in a vehicle collision.

[0094] However, if the depth D2 of the reinforcing rib 382 is too large, it is difficult to form the reinforcing rib 382 in the top plate 31. Therefore, the depth D2 is preferably less than 15.0 times the plate thickness t of the top plate 31. Similarly, regarding the longitudinal wall 34, if the depth D1 of the reinforcing rib 381 is too large, it is also difficult to form the reinforcing rib 381. Therefore, the sum of the depths D1 of more than one reinforcing rib 381 in the longitudinal wall 34 is preferably less than 15.0 times the plate thickness t of the top plate 31. For the case where more than one reinforcing rib 381 is provided in the longitudinal wall 35, from the viewpoint of formability, the sum of the depths D1 of more than one reinforcing rib 381 in the longitudinal wall 35 is also preferably less than 15.0 times the plate thickness t of the top plate 31.

[0095] For example, when reinforcing ribs 381, which are rectangular in cross-sectional view from the outer member 30 of the sill beam, are provided relative to the longitudinal walls 34 and / or 35, the difference in cross-sectional length is less likely to increase compared to the case where no reinforcing ribs 381 are provided, since the top of the reinforcing ribs 381 extends parallel to the reference line R1. Therefore, it is preferable that each reinforcing rib 381 does not have a portion that extends substantially parallel to the reference line R1 in cross-sectional view from the outer member 30 of the sill beam. As a result, the cross-sectional length of the longitudinal walls 34 and / or 35 is more likely to increase compared to the case where no reinforcing ribs 381 are provided, thereby improving the effect of the reinforcing ribs 381 on extending the cross-sectional length. Consequently, when the outer member 30 of the sill beam deforms during a car collision, the strain is more easily dispersed in the cross-sectional length direction, further reducing the strain of the ridge-like portions formed by deformation.

[0096] In this embodiment, from the cross-sectional view of the outer member 30 of the sill beam, the angle θ between the side of the reinforcing rib 381 on the top plate 31 side and the reference line R1 is, for example, 120° or more, preferably 135° or more, and more preferably 150° or more. By ensuring a relatively large angle θ between the side of the reinforcing rib 381 and the reference line R1, the reinforcing rib 381 is more likely to deform in the open direction during a vehicle collision, and the material of the reinforcing rib 381 is more likely to be supplied to the ridge portion 32 or 33. As a result, cracks at the ridge portions 32 and 33 are less likely to occur.

[0097] In the sill beam outer member 30 of this embodiment, the reinforcing rib 382 of the top plate 31 is disposed offset from the longitudinal wall 35 downward relative to the width center C0 of the top plate 31. More specifically, in the cross-section of the sill beam outer member 30, the bottom center C1 of the reinforcing rib 382 is disposed at a position lower than the width center C0 of the top plate 31. This avoids interference between the reinforcing rib 382 of the top plate 31 and the energy absorption member 50. In addition, the lower part of the sill beam outer member 30 tends to have higher stiffness, thus suppressing the rotation of the sill beam outer member 30 downward towards the vehicle body during a side collision and reducing the intrusion of the sill beam outer member 30 into the lower part of the vehicle body.

[0098] In this embodiment, when forming a door ring structure 100 comprising an upper A-pillar outer member 11, a lower A-pillar outer member 12, a B-pillar outer member 20, and a sill beam outer member 30 from an annular blank 60, the top plate 31 is held by a pressure plate 83 and a buffer member 812 provided on the punch 81 at the position of the sill beam outer member 30. That is, from the initial stage of forming, the top plate 31 of the sill beam outer member 30 is in contact with the pressure plate 83 and the buffer member 812. This ensures the cooling rate of the top plate 31, thus the microstructure of the top plate 31 is more likely to become a martensitic single-phase structure, and the stress in the top plate 31 is more easily released. Therefore, the springback of the sill beam outer member 30 can be reduced, and the torsion of the door ring structure 100 caused by springback can be suppressed. Therefore, the dimensional accuracy of the door ring structure 100 can be improved.

[0099] In this embodiment, the sill beam outer member 30 is formed by hot stamping. That is, the sill beam outer member 30 is a hot-stamped member. Therefore, the sill beam outer member 30 contains a martensitic phase in its microstructure. For example, the martensite fraction in the cross-section of the sill beam outer member 30 can be 80% or more. The martensite fraction is preferably 85% or more, more preferably 90% or more. The martensite fraction can be determined as follows: In a cross-section at any position of the sill beam outer member 30, at a position 20 mm or more away from the top of the flanges 36 and 37 and 10 mm or more away from each of them, more than 10 analytical samples (e.g., about 10 mm in size on the long side) are cut out, with the plate thickness direction as the observation surface. Each analytical sample is then ground and etched using Lepera reagent. Then, an optical microscope is used to observe the position 1 / 4 of the distance from the surface of the analytical sample in the plate thickness direction at 1000x magnification to obtain an optical microscope photograph. The obtained optical microscope images can be analyzed using commercially available image analysis software (Photoshop CS5, made by Adobe) to determine the martensite area ratio as the martensite fraction.

[0100] As an image analysis method, the maximum brightness value Lmax and minimum brightness value Lmin of the image are obtained. The portion of pixels with brightness values ​​between Lmax-0.3(Lmax-Lmin) and Lmax is designated as the white area. The proportion of pixels in the white area to the total number of pixels is calculated, thereby determining the martensite fraction. This image analysis is performed on a total of 10 observation points for each analyzed sample to determine the martensite fraction, and the average value is taken as the martensite fraction of the sill beam outer component 30.

[0101] <Second Implementation Method>

[0102] Figure 4 This is a cross-sectional view of the sill beam outer member 30A according to the second embodiment. The sill beam outer member 30A of this embodiment has the same characteristics as the sill beam outer member 30 of the first embodiment (…). Figure 1 and Figure 2A It has the same structure. However, the sill beam outer member 30A differs from the sill beam outer member 30 of the first embodiment in that the longitudinal walls 34 and 35 each include reinforcing ribs 381.

[0103] Reference Figure 4 Each longitudinal wall 34, 35 is provided with a single reinforcing rib 381. The reinforcing rib 381 protrudes from the reference line R1 toward the inner side of the sill beam outer member 30A in the cross section. However, in the longitudinal walls 34 and / or 35, the reinforcing rib 381 may also be provided in such a way that it protrudes from the reference line R1 toward the outer side of the sill beam outer member 30A.

[0104] In the longitudinal wall 34, the stiffener 381 has a depth D1 that is more than 4.0 times the thickness t of the top plate 31. In the longitudinal wall 34, the depth D1 of the stiffener 381 can also be less than 15.0 times the thickness t of the top plate 31.

[0105] In longitudinal wall 35, similar to longitudinal wall 34, stiffener 381 also has a depth D1 that is at least 4.0 times the thickness t of top plate 31. In longitudinal wall 35, the depth D1 of stiffener 381 can also be less than 15.0 times the thickness t of top plate 31. Although the figures are omitted, in each of the longitudinal walls 34, 35 of the sill beam outer member 30A, the angle θ formed by the side of stiffener 381 and the reference line R1 can be set in the same way as in the first embodiment.

[0106] Even the sill beam outer member 30A of this embodiment can achieve the same effect as the sill beam outer member 30 of the first embodiment. That is, even with the structure of this embodiment, the strain generated in the sill beam outer member 30A during a side pillar collision of a vehicle can be dispersed, and the fracture of the sill beam outer member 30A can be suppressed.

[0107] <Third Implementation Method>

[0108] Figure 5 This is a cross-sectional view of the sill beam outer member 30B according to the third embodiment. The sill beam outer member 30B of this embodiment has the same characteristics as the sill beam outer members 30 and 30A of other embodiments (…). Figure 2A and Figure 4 The basic structure is roughly the same. However, the outer member 30B of the sill beam differs from the other outer members 30 and 30A of the sill beam in the shape of the reinforcing rib 381.

[0109] In this embodiment, two reinforcing ribs 381 are provided in a stepped manner in each of the longitudinal walls 34 and 35. In this embodiment, in each of the longitudinal walls 34 and 35, one reinforcing rib 381 has a shape that protrudes outward from the outer side of the sill beam outer member 30B, while the other reinforcing rib 381 has a shape that is recessed inward from the inner side of the sill beam outer member 30B. However, in this embodiment, the sum of the depths D1 of the plurality of reinforcing ribs 381 in each of the longitudinal walls 34 and 35 is more than 4.0 times the plate thickness t of the top plate 31. Therefore, even with the structure of this embodiment, as in other embodiments, it is possible to disperse the strain generated in the sill beam outer member 30B during a side pillar collision, and to suppress the fracture of the sill beam outer member 30B. In each of the longitudinal walls 34 and 35, the sum of the depths D1 of the plurality of reinforcing ribs 381 can also be less than 15.0 times the plate thickness t of the top plate 31. In addition, in each of the longitudinal walls 34 and 35, the angle θ (not shown) formed by the side of the reinforcing rib 381 closest to the top plate 31 and the baseline R1 can be set in the same way as in the first embodiment.

[0110] In the door ring structure 100 ( Figure 1 In the case of the sill beam outer member 30A of the second embodiment or the sill beam outer member 30B of the third embodiment, the door ring structure 100 can be manufactured by the same manufacturing method as the first embodiment. For example, in cases where, as with the sill beam outer members 30A and 30B, there are portions in the reinforcing ribs 381 of the longitudinal walls 34 and / or 35 that form negative angles, i.e., portions that form angles that extend inward relative to the stamping direction, the reinforcing ribs 381 can be further formed using wedges or the like.

[0111] Door ring structure 100 including any one of the sill beam outer components 30, 30A, and 30B Figure 1 It can also be like Figures 6A-6C It is manufactured using a different manufacturing method than that described in the first embodiment, as shown.

[0112] Figures 6A-6C This is for illustrating the sill beam outer member 30 including the first embodiment. Figure 2A ) door ring structure 100 ( Figure 1A schematic diagram of the manufacturing method of [the material]. The manufacturing method here includes the same preparation and heating steps as described in the first embodiment, but the forming step differs from that in the first embodiment. For example... Figures 6A-6C As shown, in the molding process, the mold 80 of the first embodiment is used ( Figure 3C Different molds 80A shape the heated blank 60 into a ring-shaped door ring structure 100 when viewed from above. Figure 1 Then quench it.

[0113] exist Figures 6A-6C The image shows the outer component 30 of the sill beam in mold 80A. Figure 1 and Figure 2A The cross-section of the corresponding part. Mold 80A includes a punch 81A, a die 82, and a pressure plate 83. Mold 80A is mainly structurally similar to mold 80 of the first embodiment in that of the punch 81A. Figure 3C )different.

[0114] In the mold 80 of the first embodiment, the punch 81 is used to form the outer member 30 of the sill beam. Figure 2A The part includes a buffer 812 configured to be housed within the punch body 811. Figure 3C On the other hand, in mold 80A, the portion of punch 81A used to form the outer member 30 of the sill beam does not include such a buffer. Punch 81A has a forming surface corresponding to the outer member 30 of the sill beam. A reinforcing rib 382 is provided on the top surface of punch 81A. Figure 2A A recess 812a is provided on the side of the punch 81A for forming a reinforcing rib 381. Figure 2A and Figure 2B The step section 811a of )

[0115] like Figure 6A As shown, in the forming process, firstly, the blank 60 is positioned between the punch 81A and the die 82, and between the punch 81A and the pressure plate 83. Then, the die 82 and the pressure plate 83 are moved relative to the punch 81A in the stamping direction, bringing the die 82 and the pressure plate 83 closer to the punch 81A. Thus, firstly, the blank 60 is clamped by the pressure plate 83 and the punch 81A. More specifically, as... Figure 6B As shown, the top plate 31 of the blank 60 is formed as the outer member 30 of the sill beam. Figure 2A The portion of the blank 60 is held by the pressure plate 83 and the punch 81A to form a reinforcing rib 382.

[0116] Then, as Figure 6CAs shown, the blank 60 is stamped by the punch 81A and the die 82 to form longitudinal walls 34 and 35 and flanges 36 and 37. One or more reinforcing ribs 381 are formed in the longitudinal wall 34. More specifically, while maintaining the blank 60 held between the pressure plate 83 and the punch 81A, the punch 81A is brought relatively close to the die 82 in the stamping direction. As a result, the elastic member 85 contracts, and the die 82 moves relative to the pressure plate 83 towards the punch 81A side. Then, the blank 60 is stamped by the punch 81A and the die 82, forming a shape along the forming surface of the punch 81A. The blank 60 is held between the punch 81A and the die 82 and between the punch 81A and the pressure plate 83. The blank 60 dissipates heat through the die 80A (rapid cooling), and its microstructure transforms into martensite. Although the illustration is omitted, the part of the door ring structure 100 other than the threshold beam outer member 30 is also formed by the mold 80A.

[0117] exist Figures 6A-6C The text describes the manufacture of a door ring structure 100 including the threshold beam outer member 30 of the first embodiment. Figure 1 Examples include door ring structures 100 that include sill beam outer members 30A or 30B in other embodiments, but even these can be achieved through... Figures 6A-6C The manufacturing method shown is used for manufacturing. When manufacturing the door ring structure 100 including the outer door ring members 30, 30A, and 30B, if there are portions in the reinforcing ribs 381 of the longitudinal walls 34 and / or 35 that form negative angles—that is, portions that form angles relative to the stamping direction and extend inwards—it is possible to further form the reinforcing ribs 381 using wedges or the like. Alternatively, it is possible to appropriately tilt the outer door ring members 30, 30A, and 30B relative to the stamping direction so that negative angle portions are not formed in the outer door ring members 30, 30A, and 30B.

[0118] The embodiments of this disclosure have been described above, but this disclosure is not limited to the above embodiments. Various modifications can be made as long as they do not depart from its spirit.

[0119] The above embodiments can be appropriately combined. For example, in the threshold beam outer member 30 of the first embodiment, the structure of the longitudinal wall 35 of the threshold beam outer member 30A of the second embodiment or the threshold beam outer member 30B of the third embodiment can also be applied. Similarly, the structure of the longitudinal wall 34 or 35 of the threshold beam outer member 30B of the third embodiment can also be applied to the longitudinal wall 34 or 35 of the threshold beam outer member 30A of the second embodiment. That is, it is also possible to form only one reinforcing rib 381 in one of the longitudinal walls 34 and 35, and multiple reinforcing ribs 381 in the other of the longitudinal walls 34 and 35. Alternatively, it is also possible that no reinforcing rib 381 is provided in either of the longitudinal walls 34 and 35 in each threshold beam outer member 30A and 30B.

[0120] In each of the threshold beam outer members 30, 30A, and 30B in the above embodiments, the longitudinal walls 34 and 35 each include one or two reinforcing ribs 381. However, each longitudinal wall 34 and 35 may also include three or more reinforcing ribs 381 that protrude from the baseline R1 toward the inner or outer side of the threshold beam outer member from a cross-sectional view of the outer member. When the longitudinal wall 34 and / or the longitudinal wall 35 includes three or more reinforcing ribs 381, the sum of the depths D1 of the reinforcing ribs 381 in the corresponding longitudinal wall is also more than 4.0 times the plate thickness t of the top plate 31.

[0121] In the threshold beam outer member 30 of the first embodiment described above, a reinforcing rib 382 is provided on the top plate 31. However, as... Figure 7 As shown, the top plate 31 may also have multiple reinforcing ribs 382 arranged along the vertical direction of the vehicle body. Alternatively, as... Figure 8 As shown, the top plate 31 may also be without reinforcing ribs 382. Similarly, in other embodiments of the sill beam outer members 30A and 30B, the top plate 31 may include multiple reinforcing ribs 382, ​​or it may not include reinforcing ribs 382. When the top plate 31 includes multiple reinforcing ribs 382, ​​the depth D2 of each reinforcing rib 382 may be the same as or different from the depth D2 of the other reinforcing ribs 382. Preferably, the depth D2 of at least one of the multiple reinforcing ribs 382 is more than 5.0 times the plate thickness t of the top plate 31.

[0122] In the sill beam outer members 30, 30A, and 30B of the above embodiments, the reinforcing ribs 382 of the top plate 31 have a generally triangular shape in cross-sectional view. However, the cross-sectional shape of the reinforcing ribs 382 is not limited to this. Similarly, the shape of the reinforcing ribs 381 provided on the longitudinal walls 34 and / or 35 is not particularly limited. The reinforcing ribs 381 and 382 may also have polygonal shapes such as rectangles or trapezoids in cross-sectional view. However, from the viewpoint of further extending the cross-sectional length of the sill beam outer members 30, 30A, and 30B, the reinforcing ribs 381 of the longitudinal walls 34 and / or 35 preferably have a shape such as a triangular shape or a curved shape, in which the top does not extend substantially parallel to the reference line R1. Similarly, the reinforcing ribs 382 of the top plate 31 may also have a shape such as a triangular shape or a curved shape, in which the bottom does not extend substantially parallel to the straight line L0.

[0123] In the above embodiment, the annular blank 60, which serves as the blank for the door knocker structure 100, includes four steel plates 61, 62, 63, and 64. However, the blank 60 may also be a structure formed by two or three steel plates, or it may be a structure including five or more steel plates. The positions of the joints between the blank 60 and the steel plates in the door knocker structure 100 can be appropriately changed.

[0124] In the above embodiments, the multiple steel plates forming the annular blank 60 can be single-layered or multi-layered. That is, these steel plates can be plates composed of a single steel plate or plates composed of multiple overlapping steel plates.

[0125] In the above embodiment, the sill beam outer components 30, 30A, and 30B are manufactured by hot stamping. To ensure sufficient depths D1 and D2 of the reinforcing ribs 381 and 382, ​​the sill beam outer components 30, 30A, and 30B are preferably manufactured by hot stamping. However, the sill beam outer components 30, 30A, and 30B can also be manufactured by cold forming. Furthermore, in the above embodiment, the sill beam outer components 30, 30A, and 30B are integrally stamped with other frame components 11, 12, and 20, but the sill beam outer components 30, 30A, and 30B can also be stamped independently of the other frame components 11, 12, and 20.

[0126] In the above embodiment, the door knocker structure 100 includes any one of the sill beam outer components 30, 30A, and 30B, the upper outer component 11 of the A-pillar, the lower outer component 12 of the A-pillar, and the outer component 20 of the B-pillar. However, the door knocker structure 100 may also include other constituent elements. For example, such as... Figure 9 As shown, the door knocker structure 100 may further include a C-pillar outer member 90. The door knocker structure 100 of the above embodiment has a single-ring shape. On the other hand, Figure 9 The door ring structure 100 shown has a double-ring shape. In the case of a door ring structure 100 with an integrally formed double-ring shape, the blank that serves as its blank also has a double-ring shape.

[0127] Example

[0128] The present disclosure will be further described in detail below through embodiments. However, the present disclosure is not limited to the following embodiments.

[0129] To confirm the effectiveness of this disclosure, CAE analysis was performed on the outer member of the threshold beam described in the above embodiments, while varying the depth of the stiffeners in the longitudinal wall, using commercially available software (LS-DYNA R9.3.1, manufactured by Ansys). The analysis conditions and results are shown in Table 1.

[0130] [Table 1]

[0131]

[0132] In this analysis, for Comparative Examples 1-3 and Examples 1-6 shown in Table 1, the equivalent plastic strain was evaluated by colliding a vehicle body with a door ring structure, including a sill beam outer member, with a 75° collision angle and a speed of 32 km / h against a 254 mm diameter pole, according to the side impact test standards of the National Highway Traffic Safety Administration (NHTSA). More specifically, for each comparative example and example, the equivalent plastic strain was evaluated at 2 mm intervals along the ridge-like portion caused by the deformation of the sill beam outer member during the collision, within a range from 34 mm to the sill beam outer member, extending towards the sill beam outer member. A steel sheet with a tensile strength of 1470 MPa and a thickness of 1.2 mm was used as the blank material for the sill beam outer member.

[0133] In the threshold beam outer member of Comparative Example 1, no reinforcing ribs were provided in the top plate and the two longitudinal walls. In the threshold beam outer member of Comparative Example 2, one reinforcing rib was provided in the top plate, but no reinforcing ribs were provided in the two longitudinal walls. In the threshold beam outer member of Comparative Example 3, no reinforcing rib was provided in the top plate, but one convex reinforcing rib was provided in each longitudinal wall. However, in Comparative Example 3, the depth of the reinforcing ribs in each longitudinal wall was less than 4.0 times the thickness of the top plate (1.2 mm). On the other hand, in the threshold beam outer member of Example 1, no reinforcing rib was provided in the top plate, but one concave reinforcing rib was formed in each longitudinal wall. In the threshold beam outer member of Example 2, no reinforcing rib was provided in the top plate, but two reinforcing ribs were formed in a stepped (concave-convex) shape in each longitudinal wall. In the threshold beam outer member of Example 3, one reinforcing rib was provided in the top plate, and two reinforcing ribs were formed in a stepped shape in each longitudinal wall, similar to Example 2. In the sill beam outer component of Embodiment 4, there are no reinforcing ribs on the top plate, but one concave reinforcing rib is provided on each longitudinal wall. In the sill beam outer component of Embodiment 5, there are no reinforcing ribs on the top plate, but one convex reinforcing rib is provided on each longitudinal wall. In the sill beam outer component of Embodiment 6, there are no reinforcing ribs on the top plate, but one concave reinforcing rib is provided only on one longitudinal wall (the longitudinal wall on the upper side of the vehicle body). In Embodiments 1 to 6, the total depth of the reinforcing ribs on each longitudinal wall is more than 4.0 times the thickness of the top plate (1.2 mm).

[0134] As shown in Table 1, in Comparative Example 3, where relatively shallow reinforcing ribs (ribs with a depth less than 4.0 times the thickness of the top plate) are formed on each longitudinal wall, the maximum value of the equivalent plastic strain is larger compared to Comparative Examples 1 and 2, where no reinforcing ribs are formed on each longitudinal wall. That is, in Comparative Example 3, although reinforcing ribs are provided on each longitudinal wall, it results in strain concentration. On the other hand, in Examples 1 to 6, where reinforcing ribs are formed on each longitudinal wall with a total depth of 4.0 times or more the thickness of the top plate, the maximum value of the equivalent plastic strain is significantly smaller compared to Comparative Examples 1 to 3. In Example 1, where the total depth of the reinforcing ribs is set to 4.2 times the thickness of the top plate, the maximum value of the equivalent plastic strain is reduced by more than 20% compared to Comparative Example 1. In Example 4, where the conditions other than the total depth of the reinforcing ribs are the same as in Example 1, the maximum value of the equivalent plastic strain is reduced by more than 25% compared to Comparative Example 1. In Example 4, the total depth of the reinforcing ribs in each longitudinal wall is 6.7 times the thickness of the top plate, which is greater than in Example 1. Therefore, it was confirmed that by providing one or more reinforcing ribs in the longitudinal wall such that their total depth is at least 4.0 times the plate thickness, strain concentration at the deformation site of the sill beam outer member is mitigated during side column impact. The greater the total depth of the reinforcing ribs, the more the strain concentration is mitigated. The total depth of the reinforcing ribs in each longitudinal wall only needs to be at least 4.0 times the thickness of the top plate, but preferably at least 5.0 times the thickness of the top plate, and more preferably at least 6.0 times the thickness of the top plate.

[0135] In Example 6, stiffeners are provided only on the longitudinal walls on the upper side of the vehicle body. Comparing Example 6 with Example 2, where the total depth of the stiffeners in each longitudinal wall is the same, the maximum value of the equivalent plastic strain is approximately the same. Therefore, it is confirmed that even with more than one stiffener on only one longitudinal wall, a reduction in strain concentration can be achieved. However, considering the effect of deformation of the sill beam outer member on the upper and lower edges of the vehicle body, it is preferable to provide stiffeners on both longitudinal walls.

[0136] In Example 4, each longitudinal wall is provided with a reinforcing rib recessed towards the inner side of the sill beam outer member. On the other hand, in Example 5, each longitudinal wall is provided with a reinforcing rib protruding towards the inner side of the sill beam outer member. In either Example 4 or 5, the maximum value of the equivalent plastic strain is significantly reduced compared to Comparative Example 1. Therefore, regardless of the concavity or convexity of the reinforcing rib, strain concentration at the deformation site of the sill beam outer member can be mitigated. However, since the reduction in the maximum value of the equivalent plastic strain in Example 5 compared to Comparative Example 1 is greater than the reduction in the maximum value of the equivalent plastic strain in Example 4 compared to Comparative Example 1, it is preferable to include a reinforcing rib protruding towards the outer side of the sill beam outer member in the longitudinal wall to further mitigate strain concentration.

[0137] When comparing embodiments 2 and 3, which differ only in the presence or absence of reinforcing ribs in the top plate, the maximum value of the equivalent plastic strain in embodiment 3, where reinforcing ribs are formed in the top plate, is lower. Therefore, to further mitigate strain concentration, it is preferable to provide reinforcing ribs in the top plate in addition to the longitudinal walls. The depth of the reinforcing ribs in the top plate is preferably 5.0 times or more the thickness of the top plate, more preferably 6.0 times or more the thickness of the top plate, and even more preferably 7.5 times or more the thickness of the top plate.

[0138] Explanation of reference numerals in the attached figures

[0139] 30, 30A, 30B, Sill beam outer components; 31, Top plate; 32, 33, Ridge section; 34, 35, Longitudinal wall; 36, 37, Flange; 381, Reinforcing rib (first reinforcing rib); 382, ​​Reinforcing rib (second reinforcing rib); 60, Blank; 80, 80A, Mold; 81, 81A, Punch; 811, Punch body; 812, Buffer component; 82, Stamping die; 83, Pressure plate; 100, Door ring structure.

Claims

1. A door sill beam outer component, which is a door sill beam outer component for automobiles, wherein, The external components of the threshold beam have: roof; Two longitudinal walls are disposed on both sides of the top plate and are connected to the top plate via ridge portions; and A flange, which connects to the two longitudinal walls on the side of each longitudinal wall opposite to the side where the top plate is located. The outer component of the threshold beam is formed of a steel plate with a tensile strength of over 980 MPa. At least one of the two longitudinal walls includes one or more first reinforcing ribs, which extend along the long side of the outer member of the threshold beam. In the cross-section of the outer member of the sill beam, with the straight line connecting the end of the top plate side of the at least one longitudinal wall to the end of the flange side as the reference line, one or more first reinforcing ribs protrude from the reference line toward the inner or outer side of the outer member of the sill beam. The sum of the depths of the one or more first reinforcing ribs relative to the baseline is more than 4.0 times the thickness of the top plate.

2. The sill beam outer component according to claim 1, wherein, The two longitudinal walls each include one or more first reinforcing ribs.

3. The sill beam outer component according to claim 1, wherein, The top plate includes a second reinforcing rib having a shape that is recessed toward the inside of the outer member of the sill beam and extends along the long side.

4. The sill beam outer component according to claim 3, wherein, The second reinforcing rib has a depth of more than 5.0 times the thickness of the plate.

5. The sill beam outer component according to claim 3, wherein, In the cross-section of the outer member of the threshold beam with the two longitudinal walls positioned vertically, the center of the bottom of the second reinforcing rib is positioned below the center of the top plate.

6. A door ring structure, which is a door ring structure for automobiles, wherein, The door ring structure includes the threshold beam outer component as described in any one of claims 1 to 5.

7. A manufacturing method for manufacturing the door knocker structure according to claim 6, wherein, The manufacturing method comprises: Preparation process, in which a blank that has a ring shape when viewed from above is prepared; A heating process, in which the blank is heated to above the temperature at which the austenitic phase transformation is complete; and In the forming process, the heated blank is formed into the door ring structure using a mold and then quenched. The mold includes a punch, a die, and a pressure plate. The portion of the punch used to form the outer component of the sill beam includes a punch body and a buffer member, the buffer member being opposite the pressure plate and configured to be received within the punch body. In the forming process, the portion of the blank that is formed into the top plate is clamped by the pressure plate and the buffer, and then the blank is stamped by the punch body and the die while the blank is clamped by the pressure plate and the buffer.

8. A manufacturing method for manufacturing the door knocker structure according to claim 6, wherein, The manufacturing method comprises: Preparation process, in which a blank that has a ring shape when viewed from above is prepared; A heating process, in which the blank is heated to above the temperature at which the austenitic phase transformation is complete; and In the forming process, the heated blank is formed into the door ring structure using a mold and then quenched. The mold includes a punch, a die, and a pressure plate. In the forming process, the portion of the blank that is to be formed into the top plate is held by the pressure plate and the punch, and the blank is stamped by the punch and the die to form the longitudinal wall and the flange.

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