Metal Structural Parts with High-Ductility Patches and Method for Manufacturing the Same

Abstract

A method for manufacturing a metal structural part (E) for a vehicle, the method comprising the steps of: a) preparing a flat blank (B); b) cutting out the blank (B) to create an opening (A) having a first portion (Q), the first portion (Q) of the opening (A) having a second length (lt) in a first transverse direction (T); c) welding a patch (P) to the blank (B) to cover the opening (A), the patch (P) being made of a metal having higher ductility than the material of the blank (B); and d) pressing an assembly formed of the blank (B) and the patch (P) to obtain a part (E).

Description

Technical Field

[0001] The present invention relates to the manufacture of metal structural parts for vehicles, specifically, the manufacture of white body parts, and more specifically, the manufacture of profiled materials.

Background Art

[0002] In the manufacture of vehicles, the strength and ductility of various parts may be selected to control the behavior of the vehicle in the event of a collision and to protect any occupant in the cabin. Some highly ductile parts may be used to absorb and reduce the impact in the case of an automobile collision, and such parts must be of high strength. It may be advantageous for a single part to have zones of high and low ductility. For example, in the case of a B-pillar, the upper section of this pillar must maintain its shape during a collision, and since this upper section corresponds to an area where the heads and chests of the occupants may be located, it must not penetrate into the cabin. The lower section of the pillar may be used as a controlled intrusion zone. In particular, it has been observed that when this controlled intrusion zone is made of a highly ductile material throughout its width, the B-pillar may bend at this area as shown in FIG. 8 during a side collision. To prevent this overall bending and possible breakage of the B-pillar, various methods for creating impact-absorbing zones have been developed.

[0003] Korean Patent No. 101865740 discloses a method of integrally hot stamping blanks of various forms of steel and inserting and adding a reinforcing member into slots provided in the lateral sides of a B-pillar. The reinforcing member is folded to form several overlapping layers, and this reinforcing member is assembled to the component after hot stamping and after providing slots on the sides of the component by machining. Therefore, the reinforcing member is not integrally formed. The reinforcing member absorbs impact during a collision and prevents the B-pillar from breaking. However, the layered structure of the reinforcing region may add unnecessary weight to the vehicle and thus may have an adverse effect on the overall shape.

[0004] Korean Patent No. 101865741 discloses a method of integrally hot stamping blanks of various materials and various thicknesses. In this case, a pair of reinforcing patches are spot-welded to the blank before hot stamping. The patches are arranged in two lateral regions of the notched B-pillar. These patches can absorb impact during a collision, but they do not target the region where B-pillar breakage is most likely to occur. In addition, the location of the notch may impair the overall integrity of the component.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, it is advantageous to provide a method for manufacturing a metal structural component having an impact-absorbing zone that solves the drawbacks of the prior art.

Means for Solving the Problems

[0007] A first aspect of the present invention relates to a method for manufacturing a metallic structural part for a vehicle. The structural part is a profiled member having at least one part with a U-shaped cross-section, the part having a bottom and two side walls. The part has a longitudinal direction, a first transverse direction and a second transverse direction, and when viewed in the U-shaped cross-section of the part, - a bottom is formed, the bottom having a direction coinciding with the first transverse direction, - two side walls are formed, the two side walls having a direction coinciding with the second transverse direction.

[0008] It should be noted that some structural parts of the structure of a vehicle, more specifically an automobile, have a U-shaped cross-section.

[0009] An intermediate zone of the part having a U-shaped cross-section has a first length defined along the longitudinal direction, the intermediate zone being made of a metal having a higher ductility than the main material of the part surrounding the intermediate zone. In this way, two materials with different ductilities are combined. The method comprises a) preparing a flat blank having a longitudinal direction and a first transverse direction, the blank preferably being made of steel, such as ultra-high strength steel (UHSS). b) cutting out the blank to create an opening having a first part, the first part of the opening having a second length in the first transverse direction. By cutting out an appropriate part in this way, the area of the metallic structural part without material of the blank can be controlled. c) For example, it includes the step of welding a patch to the blank by spot welding to cover the opening. In this way, in some regions of the blank, the blank is welded to the patch, while in other regions, the patch covers the opening. The welding process creates a mechanical joint or junction between the patch and the blank. The patch is made of a metal having greater ductility than the material of the blank. For example, the patch may preferably be made of very high strength steel (VHSS) or extra high strength steel (EHSS). Therefore, the region of the opening covered by the patch has higher ductility than the region made of the material of the blank. d) Press working (stamping) the assembly formed by the blank and the patch to obtain a component having at least one part with a U-shaped cross-section, where at least a part of the bottom of this part corresponds to the patch of the above-mentioned first defined length, and the first part of the opening of the blank having a second length in the first lateral direction extends from one side wall to the other side wall of at least one of the side walls of the part.

[0010] In this way, when an impact is applied to a part of the bottom covered by the patch, the metal structural part, more specifically the patch, absorbs a large amount of the impact energy and deforms.

[0011] In addition, the patch provides a high mechanical continuity between the side walls of the U-shaped cross-section, because the two side walls are mechanically connected through the patch.

[0012] In addition, the mechanical response of the metal structural part when an impact is applied to a part of the bottom covered by the ductile patch is improved. The reason is that a large amount of the impact energy can be absorbed by the deformation of the bottom together with the deformation of both side walls, because the patch transmits the impact stress along the entire extension in the first lateral direction.

[0013] In addition, the metal structural component is manufactured in a simple manner by welding a patch to a blank and then pressing an assembly including the patch and the blank welded to each other. In addition, the metal structural component can be manufactured in an even simpler manner since this is sufficient to notch a single opening in the blank, weld a single patch to the blank, and press an assembly including the single patch and the blank.

[0014] In some embodiments, the first side wall of the portion having a U-shaped cross section has a first curved portion, the first curved portion joining the first side wall to the bottom of the portion having a U-shaped cross section, the first curved portion having a curvature greater than the curvature of the bottom of the portion, and / or the second side wall of the portion having a U-shaped cross section has a second curved portion, the second curved portion joining the second side wall to the bottom of the portion having a U-shaped cross section, the second curved portion having a curvature greater than the curvature of the bottom of the portion.

[0015] In this way, the curvature of the U-shaped cross section of the first and / or second curved portions is greater than the curvature of the bottom of the U-shaped cross section. The first and / or second curved portions form a transition region between the bottom and the side wall of the portion having a U-shaped cross section. It is preferable to reduce the curvature of the transition region, the purpose being to reduce the abruptness of the transition between the bottom and the side wall.

[0016] In some embodiments, step c) is performed such that the patch covers the entire opening of the blank. In this way, the mechanical continuity is enhanced over the entire opening.

[0017] In some embodiments, a large patch (P) is welded to a blank (B) such that a first portion (DZ) of the patch (P) covers an opening (A) of the blank (B) and a second portion (RZ) of the patch (B) is welded to the blank (B) in an overlapping state, thereby making it possible to create a region of a part (E) having a double thickness. The patch (P) is made of a single material throughout, and this material has higher ductility than the main material of the blank. The second portion can reinforce a metal structural part. In addition, by doing so, in the same manufacturing step, that is, by notching the opening, welding the patch to the blank, and pressing the welded patch and blank, a portion of the metal structural part is reinforced while the ductility of another portion of the metal structural part is increased. The material of the blank preferably overlaps with the second portion of the patch or most of the second portion of the patch. In some of these embodiments, the maximum length of the patch is at least three times the maximum length of the first portion of the patch. By doing so, when an impact is applied to a portion of the bottom where the patch covers the opening, most of the deformation of the patch occurs in the ductile portion of the patch.

[0018] In some embodiments, the opening notched in step b) has a maximum length in the longitudinal direction, and step d) is performed such that the opening extends from one side wall along the entire longitudinal direction to the other side wall. By doing so, there will be a long portion of the opening in the longitudinal direction within the side wall. The ductility of this long portion is increased when this portion is covered with a ductile patch.

[0019] In some embodiments, the opening notched in step b) has a maximum length in the longitudinal direction, a first section of the maximum length of the opening includes a first portion of the opening, a second section of the maximum length of the opening includes a second portion of the opening, the second portion has a length smaller than the length in the first transverse direction of the first portion in the first transverse direction, and during the implementation of step d), the second portion of the opening is laterally limited by the bottom of the portion having a U-shaped cross section along the second section of the maximum length. By doing so, only a part of the entire length of the opening as seen in the longitudinal direction enters the side wall, specifically at the first portion of the opening. Therefore, since the second portion of the opening is short and thus small when viewed in the first transverse direction, the patch extension required to cover the opening is low, and thus less patch material is required. In addition, although less material is used, the side wall still has a ductile portion, and this ductile portion has a reduced length in the longitudinal direction. In addition, the central portion of the bottom opening can be covered with a ductile patch. Therefore, when an impact is applied to this central portion covered with the patch, the mechanical requirements for absorbing a large amount of impact energy are met. This is because the ductility required for the deformation of the central portion is combined with the ductility required for the deformation of the side wall, thereby enabling a synergistic absorption of a large amount of impact energy. At the same time, since the second portion of the opening is short and thus small when viewed in the first transverse direction, many parts of the metal structural component, more specifically, the side wall, are made of the blank material and are therefore strong. Preferably, the entire region of the bottom, i.e., the entire region in the plane having the longitudinal direction and the first transverse direction occupied by the opening, is wider than the entire region of the side wall, i.e., the entire region in the plane tangential to the side wall occupied by the opening of the side wall.

[0020] In some embodiments, the maximum length of the opening in the longitudinal direction includes a third section, the third section includes a third portion of the opening, the third portion extends from one of the sidewalls to the other sidewall, and the second portion of the opening is located between the first portion of the opening and the third portion of the opening. By doing so, the absorbency of the energy of the impact applied to a part of the bottom covered by the patch is further improved. This is because each sidewall has two portions of the opening, an intermediate portion of the opening is located between these two portions, and the intermediate portion is located within the bottom. Therefore, by covering the opening with a ductile patch, the sidewalls can be bent at both of the two portions of the opening. This amount of energy absorption is further increased because the four portions of the opening in the sidewall are connected to each other by a single opening and, therefore, these four portions can be mechanically connected to each other via the ductile patch. Further, the amount of patch material required to cover the patch is further reduced because the longitudinal extension of the second portion can be reduced, and also because a part of the deformation is absorbed by the sidewall due to the deformation of the patch covering the third portion of the opening.

[0021] In some embodiments, the first portion of the opening includes at least one extension having a width and a length, the width is smaller than the length, and the at least one extension extends from the second portion of the opening to the sidewall of the portion having a U-shaped cross section and / or the third portion of the opening has at least one extension having a width and a length, the width is smaller than the length, and the at least one extension extends from the second portion of the opening to the sidewall of the portion having a U-shaped cross section.

[0022] In this way, the amount of patch material required is reduced. The length of the extension of the opening is the length from the start of the extension of the bottom to the end of the extension of the side wall. Preferably, the start of at least one extension is arranged at a part of the opening that is close to the end of the second part of the opening when viewed in the first lateral direction. By doing so, the amount of patch material is further reduced, while on the other hand, the response of the metal structural part to the impact applied to a part of the bottom covered by the patch by the opening is satisfactory, because the extension makes the mechanical connection between the bottom and the side wall reliable.

[0023] In some embodiments, the opening obtained in step b) is limited by the edge of the blank, and when step d) is carried out, the patch has a raised portion that enters the opening such that the thickness of the opening decreases.

[0024] In some embodiments, when step d) is carried out, the raised portion includes the entire portion of the patch covering the opening. By doing so, the mechanical continuity is enhanced throughout the opening. The raised portion of the patch can prevent the entire surface of the part from losing contact with the tool on one side during its manufacture, and losing such contact will have an adverse effect on the cooling rate of the part. By raising a part of the patch to fill the gap of the hole, it is possible to ensure the same and continuous contact of the part with the manufacturing tool. Good cooling can also make it possible to maintain the accurate tolerances in this area. Thereby, the material continuity of the area between the hole of the blank and the patch is obtained, and moreover, the behavior of the part becomes more uniform.

[0025] In some embodiments, step d) is carried out by hot stamping.

[0026] The second aspect of the present invention relates to a metal structural part configured according to any of the above-described embodiments.

[0027] In some embodiments, the metal structural component is a B-pillar. Preferably, when viewed in the longitudinal direction, the maximum length of the covered opening is less than 1 / 3 of the length of the B-pillar, and this maximum length portion is located in the lower half of the B-pillar. More preferably, the maximum length of the covered opening is at least 30 mm.

[0028] A third aspect of the present invention relates to an automobile having any one of the metal structural components of the above-described embodiments. In this way, during a side collision, the B-pillar deforms the ductile patch, and thus absorbs a large amount of impact energy by deforming some parts of the bottom and side walls covered by the patch.

[0029] The different aspects and different embodiments of the present invention described above can be combined with each other as long as they are compatible with each other.

[0030] Additional advantages and additional features of the present invention will become apparent from the following detailed description and will be specifically pointed out in the claims.

[0031] For the purpose of completing the description and providing a good understanding of the present invention, a set of drawings is provided. These drawings form an integral part of this specification and describe the embodiments of the present invention. The embodiments of the present invention should not be construed as limiting the scope of the present invention and should be understood only as an example of the implementation manner of the present invention. The drawings include the following figures.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

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Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0033] The following description should not be taken in a limiting sense of the present invention and is provided only for the purpose of explaining the broad principles of the present invention. Embodiments of the present invention will be described by way of example with reference to the drawings briefly described above.

[0034] Figures 1 and 2 schematically show a method for manufacturing a metal part of the present invention. In Figure 1, a blank B is used to manufacture the part. The blank B is a flat metal sheet (sheet metal) extending in the longitudinal direction L and the transverse direction T. For example, by laser cutting or during a punching process, an opening A is cut out from the sheet. The sheet B is preferably made of steel. A patch P of a suitable size is made from another material with high ductility, such as extra-high-strength steel (EHSS) or very-high-strength steel (VHSS). The patch P is dimensioned to cover the opening A. Next, the patch is attached by welding to cover the opening A.

[0035] Figure 2 shows the combined state of the blank and the patch after being shaped, for example, by stamping (press working), into a state of a part E having a portion with a U-shaped cross-section. In this figure, another direction H in which the side walls 2, 3 of the U-shaped portion extend is defined. The side walls 2, 3 and the bottom 1 form a U-shaped cross-section. The transition portions from each wall 2, 3 to the bottom 1 are rounded so that rounded portions R1, R2 can be formed at each transition portion. The intermediate zone Z to which the patch is attached is also formed in the U-shaped portion, and the intermediate zone Z has higher ductility than the peripheral portion of this part and has a first defined length l in the longitudinal direction.

[0036] Figure 3A is an exploded view of a metal part according to a first preferred embodiment of the present invention, in this case a B-pillar. The B-pillar is made of a main metal material, such as steel. The dimensional shape of the cross-section varies in the longitudinal direction, but a portion having a substantially U-shaped cross-section can be identified in the B-pillar, and this portion includes the intermediate zone Z. The opening A provided in the main material has an irregular shape, and various portions are provided within this opening, that is, a first portion Q having a second length lt in a part of the side walls 2, 3 and the bottom 1 of the U-shaped portion and in the first transverse direction T, a second portion S having a length shorter than lt in the first transverse direction T, and a third portion U also extending over a part of the side walls 2, 3 and the bottom 1. Each of the first and third portions Q, U has an extension 6 extending from the second portion S of the opening to each side wall 2, 3.

[0037] Patch P has a raised region 7 with a shape complementary to the shape of the opening A. As a result, during assembly, the region of the opening A has a reduced thickness compared to the surrounding material. This is shown in detail in FIG. 3B.

[0038] FIG. 4A is an exploded perspective view of a B-pillar according to a second preferred embodiment of the present invention. In this embodiment, the patch P is significantly larger than the opening A and mostly overlaps with the main material of the B-pillar. A first portion DZ of the patch P can be defined as the portion of the patch located within the opening A. This portion may also be raised to provide a seamless transition of the surface of the B-pillar from the main material to the patch. A second portion RZ of the patch P can be defined as the portion of the patch P that overlaps with the main material. This may be joined to the main material, for example, by welding. FIG. 4B shows in detail the first portion DZ assembled within the B-pillar.

[0039] FIGS. 5, 6, and 7 show various steps in the manufacture of a B-pillar according to the second embodiment. A blank B of the main material is cut or made to be flat, and a hole A is formed in the blank. In this figure, the edge defining the opening is indicated by reference numeral 4. A flat patch P is formed or cut from another flat high-ductility material. FIG. 6 shows a joint provided between the patch P and the flat blank B by spot welding, represented by spots applied around the edge 4 and within the second portion RZ of the patch. Next, the final part E, in this case the B-pillar, is hot stamped to form its three-dimensional shape, which has a portion with a U-shaped cross-section. The U-shaped cross-section provides the possibility of a configuration including the side walls 2, 3 and the bottom 1 between the side walls and between the side walls themselves, regardless of the angle or curvature between the side walls 2, 3 and the bottom 1, and includes a configuration in which the U-shape can be found within a larger shape, for example, within an Ω-shape.

[0040] Figures 8 to 12 show some of the effects when the high-ductility patch P of the present invention is provided on automotive parts, for example, a B-pillar. Figure 8 shows a monolithic B-pillar manufactured according to a known process, for example, by integral hot stamping. As a result of applying a lateral impact to the B-pillar, the ductile region deforms more than the main material. However, since the ductile region extends laterally across the entire part, this part has a tendency to bend and, in some cases, break along the illustrated line. Such bending or breaking reduces the integrity of the vehicle cabin.

[0041] Figure 9 shows, for comparison, the effect of a lateral impact on the B-pillar according to the first embodiment. In this case, the shape of the patch P exactly matches the weakest region of the B-pillar in response to the lateral impact. A smaller notch is used compared to the second embodiment, and the remainder of the part retains its integrity. During the impact, the overall deformation of the B-pillar is smaller than that observed in the known process and is substantially limited to the patch.

[0042] Figures 11 and 12 show the effect of the same lateral impact applied to the B-pillar according to the second embodiment. Similarly, major deformation occurs in the patch P, while the degree of influence on the side walls 2, 3 and the overall shape of the B-pillar is small. In Figure 12, the line indicating the major deformation region is limited within the high-ductility patch P, while the high-strength lateral region of the B-pillar remains unaffected and the interior of the vehicle cabin is not pushed in.

[0043] This technical idea can be applied to other metal parts, especially automotive articles where it is advantageous to provide an impact-absorbing region.

[0044] In this context, the term "comprises" as used in the original specification (which is often translated as "has" in the translation) and its variants (such as "comprising", etc.) should not be understood in an exclusive sense, that is, such terms should not be construed as precluding the possibility that the recited and defined content may include other elements, steps, etc.

[0045] On the other hand, it is clear that the present invention is not limited to the specific embodiments described herein, and includes any variations that can be conceived by those skilled in the art within the entire scope of the present invention as recited in the claims (for example, with respect to the selection of materials, dimensions, shapes, components, forms, etc.).

Claims

1. A method for manufacturing a metal structural component (E) for a vehicle, wherein the metal structural component (E) is a profiled bar having at least one portion with a U-shaped cross-section, the portion having a bottom (1) and two side walls (2, 3), the portion having a longitudinal direction (L), a first transverse direction (T) and a second transverse direction (H), and as seen in the U-shaped cross-section of the portion, - the bottom (1) of the portion is formed, the bottom (1) having a direction coinciding with the first transverse direction (T), - the first side wall (2) and the second side wall (3) of the portion are formed, the two side walls (2, 3) having a direction coinciding with the second transverse direction (H), an intermediate zone (Z) of the portion having the U-shaped cross-section has a first length (l) defined along the longitudinal direction (L), the intermediate zone (Z) being made of a metal having a higher ductility than the main material of the metal structural component (E) surrounding the intermediate zone (Z), the method comprising: a) providing a flat blank (B) extending in the longitudinal direction (L) and the first transverse direction (T), b) notching the blank (B) to create an opening (A) having a first portion (Q), the first portion (Q) of the opening (A) having a second length (lt) in the first transverse direction (T), c) welding a patch (P) to the blank (B) to cover the opening (A), the patch (P) being made of a metal having a higher ductility than the material of the blank (B), d) pressing the assembly formed by the blank (B) and the patch (P) to obtain the metal structural component (E) having the at least one portion with a U-shaped cross-section, with at least a part of the bottom (1) of the portion corresponding to the patch on the first defined length (l) and the first portion (Q) of the opening (A) of the blank (B) having a second length (lt) in the first transverse direction (T) extending from the first side wall (2) to the second side wall (3) of the at least one portion).

2. The first side wall (2) of the portion having a U-shaped cross section has a first curved portion (R1), and the first curved portion (R1) joins the first side wall (2) to the bottom (1) of the portion having a U-shaped cross section. The first curved portion (R1) has a curvature greater than the curvature of the bottom (1) of the portion, and / or The second side wall (3) of the portion having a U-shaped cross section has a second curved portion (R2), and the second curved portion (R2) joins the second side wall (3) to the bottom (1) of the portion having a U-shaped cross section. The second curved portion (R2) has a curvature greater than the curvature of the bottom (1) of the portion. The method according to claim 1.

3. The step c) is performed such that the patch covers the entire opening (A) of the blank (B). The method according to claim 1 or 2.

4. A first portion (DZ) of the patch (P) covers the opening (A) of the blank (B), and a second portion (RZ) of the patch (P) is welded to the blank (B) in an overlapping state, thereby creating a region of the metal structural part (E) with a double thickness. Preferably, the maximum length of the patch (P) in the longitudinal direction (L) is at least twice the maximum length in the longitudinal direction of the first portion (DZ) of the patch (P) covering the opening (A). The method according to any one of claims 1 to 3.

5. The opening (A) cut out in step b) has a maximum length in the longitudinal direction (L), and step d) is performed such that the opening (A) extends from the first side wall (2) along the entire longitudinal direction (L) to the second side wall (3). The method according to any one of claims 1 to 4.

6. 5. The method according to claim 1, wherein the opening (A) cut out in step b) has a maximum length in the longitudinal direction (L), a first section of the maximum length of the opening (A) comprising the first portion (Q) of the opening (A), and a second section of the maximum length of the opening (A) comprising the second portion (S) of the opening (A), the second portion (S) having a length in the first transverse direction (T) that is smaller than the length (lt) of the first portion (Q) in the first transverse direction, such that during step d), the second portion (S) of the opening is laterally limited by the bottom (1) of the portion having a U-shaped cross section along the second section of the maximum length.

7. 7. The method of claim 6, wherein the maximum length of the opening (A) in the longitudinal direction (L) includes a third section, the third section including a third portion (U) of the opening (A), the third portion (U) extending from one of the side walls (2) to the other of the side walls (3), and the second portion (S) of the opening (A) being located between the first portion (Q) of the opening (A) and the third portion (U) of the opening (A).

8. the first portion (Q) of the opening (A) comprises at least one extension (6) having a width and a length, the width being smaller than the length, the at least one extension (6) extending from the second portion (S) of the opening (A) to the side walls (2, 3) of the portion having a U-shaped cross section; and / or 8. The method according to claim 7, wherein the third portion (U) of the opening (A) has at least one extension (6) having a width and a length, the width being smaller than the length, and the at least one extension (6) extending from the second portion (S) of the opening (A) to the side walls (2, 3) of the portion having a U-shaped cross section.

9. 9. The method according to any one of claims 1 to 8, wherein the opening (A) cut in step b) is limited by an edge (4) of the blank, and wherein, when step d) is performed, the patch (P) has a raised portion (7) which enters the opening (A) so as to reduce the thickness of the opening (A).

10. 10. The method of claim 9, wherein when performing step d), the raised portion (7) comprises the entire portion of the patch (P) covering the opening (A).

11. The method according to any one of claims 1 to 10, wherein step d) is performed by hot stamping.

12. A metal structural part (E) manufactured according to the method of any one of claims 1 to 11.

13. The metal structural part (E) according to claim 12, wherein the metal structural part (E) is a B-pillar.

14. A motor vehicle comprising the metal structural part (E) according to claim 12 or 13.

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