Coated steel sheets for hot pressing, hot-formed components, hot-pressed parts and their manufacturing methods, forming apparatus, forming methods, battery housing brackets and battery module

Abstract

One aspect of the invention relates to a steel suitable for hot pressing, and more specifically, to an aluminum-coated steel sheet for hot pressing, a hot-formed component, and a method for manufacturing the same. Furthermore, another aspect of the invention relates to a forming apparatus and method for forming high-strength steel, and a battery casing support formed by the apparatus and method, and further to a battery pack module.

Description

Technical Field

[0001] One aspect of the invention relates to a steel suitable for hot pressing, and more specifically, to a galvanized steel sheet for hot pressing, a hot-formed component, a hot-formed part, and a method for manufacturing the same. Furthermore, another aspect of the invention relates to a forming apparatus and method for forming high-strength steel, and a battery casing support formed by the apparatus and method, and further to a battery pack module. Background Technology

[0002] With the increasing demand for lightweight and safer vehicles, the application of high-strength steel is actively underway. In recent years, due to the depletion of petroleum resources and heightened environmental concerns, regulations regarding improving vehicle fuel efficiency have become increasingly stringent. From a materials perspective, reducing the thickness of the steel sheets used can be cited as a method to improve fuel efficiency; however, reducing thickness may raise safety concerns, therefore, it must be supported by increased steel strength.

[0003] For the reasons mentioned above, the demand for high-strength steel plates continues, and various types of steel plates have been developed. However, these steel plates, due to their inherent high strength, suffer from poor workability. That is, because steel plates are classified by grade, the product of strength and elongation tends to tend to a constant value. Therefore, when the strength of the steel plate increases, the elongation, as an indicator of workability, tends to decrease.

[0004] To address the aforementioned issues, hot pressing has been proposed. Hot pressing involves processing steel sheets at easily machinable high temperatures, followed by rapid cooling at low temperatures. This process creates martensite and other low-temperature structures within the steel sheet, thereby increasing the strength of the final product. When using this method, it offers the advantage of minimizing machinability-related problems when manufacturing high-strength components.

[0005] Hot stamping is a process that involves heating a blank, stamping it to form the desired shape, and then cooling it in a closed mold to manufacture high-strength molded parts.

[0006] This hot stamping forming method, when using hot pressing forming at high temperatures, possesses an excellent elongation of over 50% at the forming high temperature. Even parts with small radii of curvature can be formed without cracks, thus ensuring the shape of formed parts that cannot be guaranteed by cold ultra-high strength forming. Furthermore, hot stamped parts manufactured by hot working (hot stamping) of sheet metal, because forming is typically performed at high temperatures with excellent formability, can be produced in a variety of shapes compared to conventional gigabit-level cold-formed materials.

[0007] However, when using the hot pressing method, the steel sheet needs to be heated to a high temperature, which causes oxidation on the surface of the steel sheet. Therefore, there is a problem that an additional oxide removal process must be performed on the steel sheet surface after stamping. As a solution to this problem, Patent Document 1 has been proposed. In Patent Document 1, an aluminized steel sheet is applied to a process of heating and rapid cooling after hot pressing or room temperature forming (referred to as "post-heat treatment"). Because there is an aluminized layer on the surface of the steel sheet, the steel sheet will not oxidize during heating.

[0008] However, when heating occurs after an aluminum plating layer has formed on the surface, problems such as melting and contamination of the equipment may occur, depending on the heating rate. Furthermore, in the case of high-strength components, hydrogen trapped inside the base steel plate may accumulate, potentially leading to hydrogen-induced delayed fracture, a problem known as component breakage.

[0009] As a solution to this problem, the following method has been proposed: The aluminized steel sheet is heated before heating to form an aluminum-iron alloy layer, and then the steel sheet with the aluminum-iron alloy coating is applied to hot pressing. That is, if the coating is alloyed within a relatively low temperature range before heating for hot pressing, even with relatively rapid heating, the problem caused by aluminum melting can be prevented because the aluminum has already been alloyed, even if heated to a temperature higher than the melting point of aluminum. Furthermore, the surface of the pre-alloyed coated steel sheet can have an alloy layer with a structure that facilitates hydrogen expulsion, thus reducing the likelihood of hydrogen-induced delayed fracture.

[0010] In addition, when using coated steel sheets as materials for hot pressing, the coated steel sheets must have sufficient formability, which can improve the coating adhesion and other properties of hot-pressed components obtained by hot pressing.

[0011] Therefore, there is a need to develop a solution that can improve the high-temperature formability of coated steel sheets used for hot pressing.

[0012] In addition, the battery system used in electric vehicles requires a battery casing to protect the internal cells. This battery casing must ensure collision safety and water tightness.

[0013] Battery casings for electric vehicles are typically made from expensive aluminum extrusions or sheets, but there are currently attempts to use steel, which is more cost-effective and easily recyclable. However, high-strength steel has poor formability, making it difficult to process into the desired shapes.

[0014] High-strength steel is sometimes only used for simple, straight-section components formed by roll forming. If such straight-section components are used to manufacture battery casings, there are alignment problems caused by the springback of the thin steel sheets and components, resulting in difficulties in butt welding the corner portions where two straight-section components meet.

[0015] To overcome this problem, as a method of wrapping the corresponding corner areas, an additional component (bracket) can be used to support the two straight components. This component has a longitudinal bend that reflects the required corner angle, and also has a flange shape that contacts the upper and lower plates of the battery pack, making it difficult to mold.

[0016] Figure 1 A schematic diagram of the side frame of the battery casing is shown. Figure 2 It shows Figure 10 The A-A' cross-sectional view. (See diagram below.) Figure 1 and Figure 2 As shown, in order to connect with the upper and lower plates, the side frame A-10 of the battery casing needs to form flanges at both the top and bottom, which is the same as the case of the bracket A-20. That is, the bracket A-20 also includes a main body A-23 and flanges (A-21, A-22) formed by bending from the main body A-23. Because the bracket A-20 includes a curved part with a radius of curvature R1, and a curved surface with a radius of curvature R2 needs to be formed in order to form flanges at both the top and bottom, the forming process is difficult.

[0017] When a component includes bends or dimensional transitions, depending on the shape characteristics of that area, the flange (A-21, A-22) surfaces may form either a stretch flange or a shrink flange. Furthermore, both types of flanges may form simultaneously if one type is dominant. In the stretch flange region, which involves thickness reduction, if the molding amount is too large or the material's formability is insufficient relative to the required shape of the component, a localized reduction in cross-sectional area due to plastic instability (necking) and subsequent fracture may occur. Additionally, in the shrink flange region, with increasing in-plane compressive load, thickness increases, as well as buckling and wrinkling problems may occur. Such wrinkles or folds can create uneven gaps in the battery pack, compromising its watertightness.

[0018] In addition, in order to ensure uniform strength and collision safety performance, bracket A-20 needs to be made of the same material as frame A-10, which is a straight component. However, when it is made of high-strength steel, it is extremely difficult to form a flange with a curved part.

[0019] For conventional cold-formed steel sheets, if they are made into ultra-high-strength steel with a tensile strength of 980MPa or more, the risk of wrinkling and breakage increases due to the insufficient strength and ductility of the material, and the processing of the bending flange becomes difficult. Therefore, the application of stamping hardened steel as an alternative material is increasing.

[0020] Stamp-hardened steel, formed at high temperatures, has low strength but sufficient ductility during forming, allowing it to be molded into complex shapes. However, because it needs to be formed in one step while maintaining high temperatures, it is difficult to apply to blank holders or drawbeads as means of controlling fracture and wrinkling, thus limiting the degree of freedom in the forming process.

[0021] In addition, high-strength steel usually has poor bending properties, which makes it impossible to form parts with small radii of curvature. However, in recent years, with the increasing demands for vehicle lightweighting and safety in electric vehicles, there is a need for a formable part that has high strength and a smaller radius of curvature than existing ones, thus making it easier to utilize space.

[0022] Furthermore, hot stamping, because the high-temperature material heated in a furnace is formed before cooling in air, cannot be sequentially formed using multi-step molds like cold forming. This drawback also makes it difficult to form parts with multiple hat shapes using hot stamping. While it's possible to form each part individually and then assemble them later, this presents performance issues and increased processing costs due to the individual molding of each component.

[0023] (Patent Document 1) U.S. Patent No. 6296805 (Patent Document 2) U.S. Patent Publication No. 2014-0056754 (Patent Document 3) Korean Patent Publication No. 10-2020-006635 (Patent Document 4) Korean Patent Publication No. 10-2023-0092430 Summary of the Invention

[0024] (a) Technical problems to be solved The first aspect of the present invention is to provide, when providing aluminum-coated steel sheet for hot pressing, a coated steel sheet with excellent hot formability at high temperature, a hot-formed component obtained by hot forming the coated steel sheet, and a method for manufacturing the same.

[0025] A second aspect of the present invention aims to provide a molding apparatus, a molding method, and a bracket manufactured by the apparatus and method for forming a bracket having flanges and bends.

[0026] A third aspect of the present invention aims to provide a molded component or a battery module including the molded component, the molded component having higher tensile strength and a smaller radius of curvature than existing components.

[0027] A fourth aspect of the present invention aims to provide a stamped part and a method for manufacturing the same, wherein the stamped part can minimize the generation of damage such as cracks when used in hot stamping to manufacture a part having multiple cap shapes.

[0028] The technical problem of this invention is not limited to the above-described contents. Additional technical problems of this invention are described throughout the specification, and those skilled in the art can readily understand these additional technical problems from the content described in this specification.

[0029] (II) Technical Solution The technical solutions of the present invention will be described below. It should be noted that, although not essential, the technical solutions of various aspects of the present invention can also be usefully used in other aspects of the technical solutions. For example, the hot-formed steel and / or manufacturing method according to the first aspect of the present invention can be usefully used in the hot-formed components according to the second to sixth aspects, various parts obtained therefrom, and their manufacturing methods. Furthermore, the manufacturing methods of the components according to the second and third aspects of the present invention, or the heat treatment conditions used therein, can be usefully used in the manufacturing processes of battery housing supports or molded parts according to the fourth to sixth aspects. Moreover, the composition and various useful parameters of the various aspects of the present invention, when appropriately combined with other aspects, can yield advantageous effects.

[0030] According to a first aspect of the present invention, a coated steel sheet for hot pressing can be provided, comprising: a base steel sheet; and an aluminum-based coating on one or both sides of the base steel sheet.

[0031] In one embodiment of the present invention, the maximum surface roughness (Rt) of the coated steel sheet for hot pressing can be 4.0-25.0 μm, and the number of peaks per unit length (RPc) can be 30-90 peaks / cm.

[0032] In addition, according to one embodiment of the present invention, the relationship between the amount of coating and Rt can satisfy the following relationship 1.

[0033] [Relation 1] 27.0≤( / 3)+(Rt / 2)≤38.0 (The unit of relation 1 is μm,) This indicates the amount of coating adhered. In this way, coated steel sheets for hot pressing, with a coating whose surface is controlled under specific conditions, can exhibit excellent high-temperature formability during the high-temperature heating process of hot pressing. Furthermore, hot-pressed components obtained from such coated steel sheets exhibit excellent coating adhesion and frictional properties.

[0034] In one embodiment of the invention, the aluminum-based coating may have a composition, by weight percent, comprising silicon (Si): 5.0-11.0%, iron (Fe): less than 10.0%, and the balance aluminum (Al) and other unavoidable impurities.

[0035] In one embodiment of the invention, the base steel plate may, by weight percent, comprise carbon (C): 0.02-0.60%, silicon (Si): 0.001-2.000%, aluminum (Al): 0.001-1.000%, manganese (Mn): 0.1-4.0%, phosphorus (P): less than 0.050%, sulfur (S): less than 0.0200%, nitrogen (N): less than 0.0200%, titanium (Ti): 0-1.0000%, niobium (Nb): 0-1.0000%, vanadium (V): 0-1.0000%, boron (B): 0-0.0100%, and chromium (Cr). : 0-1.00%, Molybdenum (Mo): 0-1.00%, Tungsten (W): 0-1.00%, Copper (Cu): 0-1.0%, Nickel (Ni): 0-1.0%, Antimony (Sb): 0-1.00%, Tin (Sn): 0-1.00%, Calcium (Ca): 0-0.10%, Magnesium (Mg): 0-0.10%, Cobalt (Co): 0-1.00%, Arsenic (As): 0-1.00%, Zirconium (Zr): 0-1.00%, Bismuth (Bi): 0-1.00%, Rare Earth Elements (REM): 0-0.3%, Balance Fe and other unavoidable impurities.

[0036] According to another aspect of the present invention, a method for manufacturing a coated steel sheet for hot pressing can be provided, comprising the following steps: preparing a base steel sheet; forming an aluminum-based coating on one or both sides of the base steel sheet to obtain a coated steel sheet; and performing a leveling rolling process on the coated steel sheet.

[0037] In one embodiment of the invention, the leveling rolling process can be carried out using rolls with a surface having Rt: 2-8 μm and RPc: 46-120 peaks / cm, with a pressing force of 100-500 tons.

[0038] This method allows for the production of hot-pressed coated steel sheets with controlled coating surfaces.

[0039] In one embodiment of the present invention, the step of forming an aluminum-based coating to obtain a coated steel sheet may be a process of immersing a base steel sheet in an Al-based plating bath containing, by weight %, Si: 5.0-11.0%, Fe: less than 4.0%, with the balance being Al and other unavoidable impurities. The base steel sheet may be a steel sheet having the aforementioned alloy composition.

[0040] In one embodiment of the present invention, the process may further include heating the plated steel sheet with the aluminum coating to a temperature range of 670-900°C for alloying treatment.

[0041] According to another aspect of the invention, a hot-pressed component can be provided, comprising a base steel plate and an aluminum-based coating with a thickness (T) of 30.0-50.0 μm formed on the base steel plate.

[0042] In one embodiment of the present invention, the maximum roughness (Rt) of the coating surface of the hot-pressed component can be 6.0-26.0 μm, and the number of peaks per unit length (RPc) can be 60-130 peaks / cm.

[0043] In one embodiment of the present invention, the relationship between the coating thickness and Rt of the hot-pressed component can satisfy the following relationship 2.

[0044] [Relationship 2] 40.0≤T+(Rt / 2)≤57.0 (The unit of Equation 2 is μm, and T represents the thickness of the coating.) This hot-pressed component exhibits excellent coating adhesion and friction characteristics. In one embodiment of the invention, the coefficient of friction of the component can be below 0.50.

[0045] In one embodiment of the present invention, the aluminum-based coating of the hot-pressed component is alloyed during the hot-pressing process, and the aluminum-based alloyed coating may be composed of an Al-Fe alloy with a total Al and Fe content of 89% by weight or more.

[0046] Although not essential, improved performance can be ensured when the steel plate or thermoformed component according to the first aspect of the invention is combined with the advantageous features of the other aspects described below.

[0047] A second aspect of the present invention provides a molding apparatus comprising: a pad; a mold disposed on the outer side of the pad in a first direction; and a punch disposed on the lower part of the pad and including a main body having a punch forming portion, wherein, when viewed in the first direction, the punch forming portion includes a straight first punch forming portion, a curved second punch forming portion having a forming portion curvature radius (Rp), and a straight third punch forming portion, the first to third punch forming portions being continuously disposed in a horizontal plane along a second direction perpendicular to the first direction, and the first to third punch forming portions including, on both sides of the first direction, a first extension surface forming portion to a third extension surface forming portion with a surface perpendicular to the first direction, and a facing portion towards the pad. The mold comprises a first main body forming portion to a third main body forming portion and a first curved surface forming portion to a third curved surface forming portion having a radius of curvature (r) between the extended surface forming portion and the main body forming portion. The pad includes a pressure surface corresponding to the first main body forming portion to the third main body forming portion. When viewed in the first direction, the mold includes a straight first mold forming portion, a curved second mold forming portion having a radius of curvature (Rd) of the mold, and a straight third mold forming portion. The first mold forming portion to the third mold forming portion are continuously arranged along the second direction. When the upper positions of the third main body forming portion and the third mold forming portion are located on the same plane, when viewed in the first direction, the first main body forming portion is located above the upper position of the first mold forming portion.

[0048] According to one embodiment of the present invention, it has the effect of enabling steel with insufficient formability (e.g., high-strength steel) to be formed.

[0049] In one embodiment of the present invention, the punch may further include a fourth punch forming part and a fifth punch forming part symmetrical to the second punch forming part and the first punch forming part, centered on the third punch forming part; the mold may further include a fourth mold forming part and a fifth mold forming part symmetrical to the second mold forming part and the first mold forming part, centered on the third mold forming part; and the pressing surface of the pad may further include a surface corresponding to the main forming part of the fourth punch forming part and the fifth punch forming part.

[0050] In one embodiment of the invention, the punch may include a support portion centered on the third punch forming portion, supporting the material before forming on the outside of the first forming portion and the fifth forming portion.

[0051] In one embodiment of the present invention, the bending radius of curvature (Rp) of the forming part may be smaller than the bending radius of curvature (Rd) of the mold.

[0052] In one embodiment of the present invention, the length (lp) of the third main body forming part in the second direction may be greater than the length (ld) of the third mold forming part in the second direction.

[0053] In one embodiment of the present invention, when viewed in the first direction, the center of the bending radius of curvature (Rd) of the mold in the second direction coincides with the center of the third main body forming part. When viewed in the first direction, the angle (θ) at which the extensions of the virtual tangents at both ends of the second punch forming part and the fourth punch forming part intersect can be between 95° and 135°.

[0054] In one embodiment of the present invention, the first to fifth mold forming portions include: a first to fifth mold curved surface forming portion, wherein the first to fifth mold curved surface forming portions form curved surfaces at positions relatively close to the punch in the first direction; and a first to fifth planar forming portion, wherein the first to fifth planar forming portions are located at positions relatively far from the punch, wherein the curved surfaces of the first to fifth mold curved surface forming portions are higher the closer they are to the punch, and when the upper positions of the third main body forming portion and the third mold forming portion are located on the same plane, when viewed in the first direction, at least a portion of the second main body forming portion may be located below the upper position of the second mold forming portion.

[0055] In one embodiment of the invention, at least one of the punch and the mold may include a cooling flow path inside, and the bending radius of curvature (Rp) of the forming part and the bending radius of curvature (r) may satisfy 25mm≤Rp(mm)+r(mm)≤30mm.

[0056] Another aspect of the present invention provides a material forming method, the method comprising: a material placement step, wherein a material having a length longer than a punch having a forming portion in a first direction is placed on the punch; a primary forming step, wherein the material is formed into the shape of a main forming portion of the punch by means of a pad located on the upper part of the punch; and a secondary forming step, wherein the material is formed into the shape of the forming portion having the punch by means of a mold located outside the pad in the first direction, wherein, in the secondary forming step, the mold forms the material in the order of an edge portion, a center portion, and an intermediate portion between the center and the edge in the first direction and a second direction perpendicular to the vertical direction.

[0057] In one embodiment of the invention, when viewed in the first direction, the forming portion includes a straight first forming portion, a curved second forming portion having a forming portion bending radius of curvature (Rp), a straight third forming portion, a curved fourth forming portion having the forming portion bending radius of curvature (Rp), and a straight fifth forming portion, wherein the middle portion of the mold is formed as a curved surface having a mold bending radius of curvature (Rd), the mold bending radius of curvature (Rd) may be greater than the forming portion bending radius of curvature (Rp).

[0058] In one embodiment of the invention, the material is a steel plate, the material placement step is performed while the material is heated to a temperature above AC3, and may further include a cooling step in which the material is cooled by at least one of the punch and the die to give it a martensitic structure.

[0059] In one embodiment of the present invention, the material may be the aforementioned coated steel sheet for hot pressing, or a hot-formed component obtained by hot-forming the coated steel sheet for hot pressing. As an example, the coated steel sheet for hot pressing and the hot-formed component may have the aforementioned alloy composition and may be manufactured by the aforementioned manufacturing method.

[0060] In one embodiment of the invention, during the material placement step, the material may include a cut formed in the first direction toward the center of the material at a position corresponding to the middle portion of the mold.

[0061] In one embodiment of the present invention, the first to fifth molding portions include: a first to fifth extension surface molding portion on a surface perpendicular to the first direction on both sides of the first direction, a first to fifth main body molding portion on a direction surface facing the pad, and a first to fifth curved surface molding portion having a bending radius of curvature (r) between the extension surface molding portion and the main body molding portion, wherein the bending radius of curvature (Rp) of the molding portion and the bending radius of curvature (r) can satisfy 25mm≤Rp(mm)+r(mm)<30mm, 3mm≤r(mm)≤10mm.

[0062] Another aspect of the present invention provides a battery housing support, the battery housing support including a molded surface having a bending radius of curvature (Rp) of the molded portion, the molded surface including: a body; a flange extending bently from an end of the body; and a curved surface connected between the body and the flange in such a manner having a bending radius of curvature (r), wherein the support is formed of boron-containing steel with a tensile strength of 1200 MPa or more, has a martensitic structure, and the bending radius of curvature (Rp) of the molded portion and the bending radius of curvature (r) satisfy 25 mm ≤ Rp (mm) + r (mm) ≤ 30 mm, 3 mm ≤ r (mm) ≤ 10 mm.

[0063] In one embodiment of the present invention, the minimum thickness (Tmin) of the flange and the initial thickness before forming (tinitial(ini)) can satisfy (tinitial-tmin) / tinitial≤0.2, and the maximum thickness (tmaximum) of the curved surface and the initial thickness before forming (tinitial) can satisfy (tinitial-tmaximum) / tinitial≥-0.4.

[0064] In one embodiment of the invention, the angle (θ) at which the extensions of the virtual tangents at both ends of the forming surface of the bracket intersect can be 95-135°.

[0065] According to one embodiment of the present invention, a battery housing support can be manufactured by the molding method described above.

[0066] According to one embodiment of the present invention, the bracket manufactured by the molding method described above can ensure the lightweight, watertightness and impact safety performance of the battery pack.

[0067] Although not essential, further improved performance can be ensured when the product according to the second aspect of the invention is combined with the advantageous features of the other aspects described below.

[0068] A third aspect of the present invention provides a high-strength steel hot-stamped forming component, the high-strength steel hot-stamped forming component comprising: a first wall extending along a first direction; a second wall extending along a direction intersecting the first wall; and a third wall extending along the first direction and along a direction intersecting the second wall, wherein a curvature portion is formed between the first wall and the second wall, the first wall, the second wall and the curvature portion are integrally formed, and satisfy the following relationship 3.

[0069] [Relationship 3] Wall height (hw) ≤ 13.4 Wall angle (θw) + 182.4 (Where, the wall height (hw) is the length from the first wall to the third wall in the direction perpendicular to the first direction, in mm; the wall angle (θw) is the angle between any line perpendicular to the first direction and the second wall, in degrees. The calculation is performed after dimensionless scaling of the left and right sides.) In one embodiment of the present invention, the high-strength steel may be the above-mentioned hot-pressed coated steel sheet.

[0070] According to one embodiment of the present invention, a molded part with high tensile strength and low curvature can be provided.

[0071] In one embodiment of the present invention, the first wall, the second wall, and the curved portion can be integrally formed by processing a sheet metal. Furthermore, the first wall, the second wall, and the curved portion can be integrally formed by processing a sheet metal, wherein the radius of curvature (r) of the curved portion is greater than or equal to 0.5 mm, and the ratio (r / t) of the thickness (t) of the sheet metal to the radius of curvature (r) can be less than 2.5.

[0072] In one embodiment of the present invention, the tensile strength of the molded component can be 1300-2100 MPa.

[0073] In one embodiment of the invention, the molded component may include: a third wall and a fourth wall, the third wall and the fourth wall being parallel to the first direction; and a fifth wall, the fifth wall connecting the third wall and the fourth wall, wherein the third wall extends from the second wall, and the first wall to the fifth wall may be integrally molded.

[0074] In one embodiment of the present invention, the angle between any line perpendicular to the first direction and the second wall can be less than 5°.

[0075] In one embodiment of the present invention, the microstructure of the molded component may be composed of martensite with an area fraction of 98% or more.

[0076] Another aspect of the present invention provides a battery pack module, the battery pack module comprising: a battery housing surrounding a battery pack; a base located at the lower part of the battery housing and connected to the battery housing to form a battery pack placement space; and a hot-stamped component disposed transversely through the interior of the battery housing and connected to the battery housing and the base.

[0077] According to one embodiment of the present invention, when manufacturing modules such as battery packs, components with high space utilization can be produced.

[0078] In one embodiment of the present invention, a plurality of the hot-stamped components may be arranged at certain intervals within the battery casing.

[0079] Although not essential, further improved performance can be ensured when the components according to the third aspect of the invention are combined with the advantageous features of the other aspects described below.

[0080] A fourth aspect of the present invention provides a stamping forming component, the stamping forming component comprising: a top plate portion; a longitudinal wall portion continuous with the top plate portion; a plurality of deformable portions having a cap shape, the deformable portions including boundary portions continuous with the longitudinal wall portions and having a preset height; and a flat plate portion having a preset length, the flat plate portion being disposed between the plurality of deformable portions and connecting two adjacent boundary portions.

[0081] In one embodiment of the present invention, the relationship between the preset length and the preset height can be determined based on the number of deformable parts.

[0082] In one embodiment of the present invention, three deformable portions may be provided, and the relationship between the preset length and the preset height can be defined by the following formula (1): w≤114.85e 0.0455h ...Formula (1), in which w represents the preset length and h represents the preset height.

[0083] In one embodiment of the present invention, four or more deformable portions may be provided, and the relationship between the preset length and the preset height can be defined by the following formula (2), w≤46.309e 0.105h ...Formula (2), in which w can represent the preset length and h can represent the preset height.

[0084] In one embodiment of the present invention, the preset length (w) can be 20 mm or more.

[0085] In one embodiment of the present invention, the stamped part can be manufactured using a hot stamping process.

[0086] In one embodiment of the present invention, the hot stamping forming method may be the method described above.

[0087] Another aspect of the present invention provides a method for manufacturing a stamped part, the method comprising the steps of: supplying a metal sheet to a processing position; performing a first stamping on the metal sheet using a first mold having a plurality of first pressing portions and an intermediate pressing portion; and performing a second stamping on the metal sheet using the first mold and a second mold having a plurality of the second pressing portions after performing the first stamping on the metal sheet.

[0088] In one embodiment of the present invention, the metal plate may be the above-mentioned hot-pressed coated steel plate.

[0089] In one embodiment of the present invention, the stamping step may use the above-described forming apparatus.

[0090] In one embodiment of the invention, in the step of supplying the metal plate to the processing position, the metal plate is supplied between the first mold and the intermediate pressure section, and the central region of the metal plate may be located facing the intermediate pressure section.

[0091] In one embodiment of the invention, in the step of supplying the metal plate to the processing position, the intermediate pressure section may be located above the second mold at the processing position.

[0092] In one embodiment of the present invention, in the step of supplying the metal sheet to the processing position, the intermediate pressure section may be located at a position where the height difference between the intermediate pressure section and the second mold is more than 65% of the height of the stamping part.

[0093] In one embodiment of the present invention, in the step of stamping the metal plate once, the intermediate pressure part is introduced into the first pressure part disposed in the center of the plurality of first pressure parts, so that the central region of the metal plate can be stamped.

[0094] In one embodiment of the present invention, in the step of performing secondary stamping on the metal plate, the second pressing part is introduced into the outermost first pressing part among the plurality of first pressing parts, so that the outer region of the metal plate can be stamped.

[0095] In one embodiment of the present invention, the metal sheet can be formed by hot stamping in the steps of primary stamping and secondary stamping.

[0096] In one embodiment of the invention, between the step of performing a first stamping of the metal sheet and the step of performing a second stamping of the metal sheet, a further step may be included: using an additional intermediate pressing part disposed outside the intermediate pressing part and the first mold to perform a stamping of the metal sheet.

[0097] (III) Beneficial Effects According to one aspect of the present invention, by controlling the coating surface of the coated steel sheet for hot pressing, high-temperature formability can be ensured during high-temperature heating in hot pressing, and the coating adhesion, friction characteristics, etc. of the hot-pressed component obtained by hot pressing can also be ensured.

[0098] According to another aspect of the present invention, a molding apparatus, a molding method, and a bracket manufactured by the apparatus and method can be provided for forming a bracket having flanges and bends, which can ensure the lightweight, watertightness, and impact safety performance of the battery pack.

[0099] According to another aspect of the invention, a molded component can be provided, which has high tensile strength and low curvature, can be manufactured in one step, and is therefore easy to process, and can be manufactured as a component with high space utilization when manufacturing modules such as battery packs.

[0100] According to another aspect of the invention, an intermediate pressing section with a height difference can be provided between the upper and lower dies, and the metal sheet can be stamped using three pressing sections. In this case, by using a step-by-step forming process that first stamps the central region of the metal sheet and then sequentially stamps the outer regions, concentrated deformation forces at specific locations on the metal sheet during stamping can be prevented. Therefore, damage to the stamped part during manufacturing can be prevented, and the part quality can be improved.

[0101] The various and advantageous advantages and effects of the present invention are not limited to the above description, and can be more easily understood in the process of describing the specific embodiments of the present invention. Attached Figure Description

[0102] Figure 1 This is a schematic diagram of the side frame of the battery casing.

[0103] Figure 2 for Figure 1 A-A' cross-sectional view.

[0104] Figure 3 This is an exploded perspective view of a molding apparatus according to one embodiment of the present invention.

[0105] Figure 4 This is a side view of a molding apparatus according to one embodiment of the present invention.

[0106] Figure 5 This is a flowchart of a molding method according to one embodiment of the present invention.

[0107] Figure 6 This is a plan view of the material to be added to a molding apparatus according to one embodiment of the present invention.

[0108] Figure 7 A schematic perspective view illustrating a single molding step in a molding method according to an embodiment of the present invention.

[0109] Figure 8 A schematic perspective view illustrating a secondary molding step in a molding method according to an embodiment of the present invention.

[0110] Figure 9a This is a perspective view of the secondary molding step in a molding method according to an embodiment of the present invention, viewed from other directions. Figure 9b A front view for observing the secondary molding step in a molding method according to an embodiment of the present invention.

[0111] Figure 10 A front view showing the cooling step in a molding method according to an embodiment of the present invention.

[0112] Figure 11 A perspective view illustrating the finishing step in a molding method according to an embodiment of the present invention.

[0113] Figure 12 A perspective view of a bracket manufactured by a molding method according to an embodiment of the present invention.

[0114] Figure 13 This is a thickness reduction rate distribution diagram of a molded article produced by a molding method according to one embodiment of the present invention.

[0115] Figure 14 This is a thickness reduction rate distribution diagram of the molded article produced by the molding method of Comparative Example 1-1.

[0116] Figure 15 for Figure 13 and Figure 14 The thickness reduction rate distribution of the molded product at the cross-section.

[0117] Figure 16 A side view showing the molding method of comparative examples 1-2.

[0118] Figure 17 A perspective view of a molded article produced by the molding method of Comparative Examples 1-2.

[0119] Figure 18 This is a perspective view of a molded component according to one embodiment of the present invention.

[0120] Figure 19 This is a front view of a molded component according to one embodiment of the present invention.

[0121] Figure 20a , Figure 20b , Figure 21a and Figure 21b For illustration of an embodiment and comparative example according to the present invention, see Table 1. Figure 20a Example 2-1 of the invention is shown. Figure 20b Comparison example 2-1 is shown. Figure 21a Examples of the invention 2-3 are shown. Figure 21b Comparison example 2-3 is shown.

[0122] Figure 22 A perspective view of a battery pack module according to an embodiment of the present invention is shown.

[0123] Figure 23 The diagram shows the space utilization when the battery pack is placed, by representing a portion of the cross section of the battery pack module according to an embodiment of the present invention, (a) for the case with a small radius of curvature, and (b) for the case with a larger radius of curvature than (a).

[0124] Figure 24 A perspective view of a stamped part according to an embodiment of the present invention is provided.

[0125] Figure 25 A perspective view is provided to illustrate a stamped part according to another embodiment of the present invention.

[0126] Figure 26 (a) is a graph showing the relationship between a preset length and a preset height of a stamped part according to an embodiment of the present invention. Figure 26 (b) is a graph showing the relationship between a preset length and a preset height of a stamped part according to another embodiment of the present invention.

[0127] Figure 27 (a) illustrates an example of the deformation force applied to a stamped part manufactured by existing manufacturing methods. Figure 27 (b) illustrates an example of the deformation force applied to a stamped part manufactured using a manufacturing method according to an embodiment of the invention.

[0128] Figure 28 A flowchart illustrating a method for manufacturing a stamped part according to one embodiment of the present invention.

[0129] Figure 29 Schematic illustration of manufacturing Figure 24The first step in the stamping process of the part.

[0130] Figure 30 Schematic illustration of manufacturing Figure 24 The second step in the stamping process of the component.

[0131] Figure 31 Schematic illustration of manufacturing Figure 24 The third step in the stamping process of the part.

[0132] Figure 32 Schematic illustration of manufacturing Figure 24 The fourth step in the stamping process of the component.

[0133] Figure 33 Schematic illustration of manufacturing Figure 25 The first step in the stamping process of the part.

[0134] Figure 34 Schematic illustration of manufacturing Figure 25 The second step in the stamping process of the component.

[0135] Figure 35 Schematic illustration of manufacturing Figure 25 The third step in the stamping process of the part.

[0136] Figure 36 Schematic illustration of manufacturing Figure 25 The fourth step in the stamping process of the component. Best practice

[0137] The technical terms used herein are for reference only to specific embodiments and are not intended to limit the invention. The singular form used herein includes the plural form unless the statement expressly indicates otherwise.

[0138] The use of "comprising" or "including" in this specification means to specify a particular characteristic, region, integer, step, action, element and / or component, and does not exclude the existence or addition of other particular characteristics, regions, integers, steps, actions, elements, components and / or groups.

[0139] Unless otherwise defined, all terms used herein, including technical and scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in common dictionaries shall be further interpreted to have meanings consistent with relevant technical literature and current disclosure, and shall not be construed as having idealized or overly formal meanings unless otherwise defined.

[0140] Furthermore, the steel plate referred to in this invention is a material in coil or sheet form that has not yet been processed into a specific shape, and the component referred to is a material processed into a non-plate-like form through a forming process. Additionally, the coating mentioned in this invention refers to a layer of metal, alloy, or intermetallic compound formed in contact with the base steel plate.

[0141] It should be noted that, unless otherwise specified, the content of each element in this invention is based on weight. Furthermore, unless otherwise specified, the proportion of crystals or structures is based on area, and unless otherwise specified, the content of gases is based on volume.

[0142] The present invention will now be described in detail.

[0143] The inventors of this invention have discovered that, when providing a coated steel sheet with an aluminum-based coating as a coated steel sheet for hot pressing, controlling the surface characteristics of the coating is different from the usual control of surface roughness. In particular, controlling Rt, which represents the maximum surface roughness of the coating, and the number of peaks per unit length (RPc, peaks / cm) has an effect on improving the high-temperature formability of the coated steel sheet for hot pressing.

[0144] First, the hot-pressed coated steel sheet according to the first aspect of the present invention may include: a base steel sheet; and an aluminum-based coating on one or both sides of the base steel sheet.

[0145] According to one embodiment of the present invention, in order to improve the formability of coated steel sheets for hot pressing during high-temperature heating for hot forming, it is intended to ensure that the coating surface is relatively rough. The larger the maximum roughness (Rt) value of the coating surface, the rougher the surface, where the maximum roughness (Rt) of the coating surface represents the distance between peaks and valleys.

[0146] Therefore, in one embodiment of the present invention, the Rt value of the coating can be 4.0-25.0 μm. When the Rt value of the coating is less than 4.0 μm, the friction area between the coating and the mold increases during hot forming of the coated steel sheet, resulting in poor high-temperature formability. On the other hand, when the Rt value of the coating exceeds 25.0 μm, during the high-temperature heating of hot forming, not only may the coating at the peaks be incompletely alloyed, but the coating may also be easily damaged due to friction with the mold during hot forming, potentially causing mold sticking.

[0147] Furthermore, in one embodiment of the present invention, the number of peaks per unit length (RPc) of the coating can be 30-90 peaks / cm. When the RPc value is less than 30 peaks / cm, there may be a risk of reduced coating adhesion. On the other hand, when the RPc value exceeds 90 peaks / cm, the contact area with the mold increases during thermoforming, the high-temperature friction coefficient increases, and this can lead to cracks or excessive coating peeling during thermoforming.

[0148] Furthermore, the inventors of this invention, through repeated and in-depth research into conditions that could improve the high-temperature formability of coated steel sheets for hot pressing, discovered that the desired goal could be achieved by controlling the relationship between the coating adhesion amount and the Rt value of the coating surface. That is, by forming a coating of a certain thickness with an appropriate adhesion amount, corrosion resistance is ensured while the frictional characteristics of the coating are improved, aiming to enhance formability during the high-temperature forming process. Simultaneously, to ensure the surface appearance of the final product, i.e., the hot-formed component, the relationship between the coating adhesion amount and the maximum surface roughness (Rt) of the coating was re-examined.

[0149] In one embodiment of the present invention, the relationship between the coating adhesion amount and the coating surface Rt value is defined as Equation 1 below, and the coating surface according to one embodiment of the present invention can satisfy Equation 1. In this case, the coating adhesion amount is based on a single side.

[0150] [Relation 1] 27.0≤( / 3)+(Rt / 2)≤38.0 (The unit of relation 1 is μm,) This indicates the amount of coating adhered. A value less than 27.0 in Equation 1 may indicate a high coating thickness and a low Rt value. In this case, the contact area between the steel plate and the mold increases during hot forming, leading to a higher coefficient of friction at high temperatures and a potential risk of deteriorated hot formability. Alternatively, a high Rt value and a low coating thickness may also indicate an excessively thin coating, resulting in poor corrosion resistance of the hot-formed component.

[0151] If the value of Equation 1 exceeds 38.0, it may indicate a situation where the coating adhesion is appropriate but the Rt value is too high. In this case, during the high-temperature heating of hot forming, not only may the coating at the peaks be incompletely alloyed, but the coating may also be easily damaged due to friction with the mold during hot forming, potentially causing mold sticking. Alternatively, it could indicate a situation where the Rt value is low but the coating adhesion is too high. In this case, during the high-temperature heating of hot forming, the unalloyed Al coating may adhere to the rollers in the heating furnace, potentially causing problems such as the coating peeling off from the steel plate.

[0152] By using a coated steel sheet for hot pressing according to an embodiment of the present invention, which has the above-mentioned characteristics, the contact area between the steel sheet and the mold can be reduced when hot forming is performed to obtain a hot-formed component, thereby improving the formability during high-temperature forming.

[0153] The aforementioned characteristics, i.e., the properties of the coating, are described based on a coating formed on one side of the base steel plate. Furthermore, when a coating is formed on both sides of the base steel plate, both sides of the coating can possess the aforementioned coating characteristics. This also applies equally to the coatings of the hot-pressed components described later.

[0154] According to one embodiment of the present invention, the base steel plate is a hot-pressing steel plate, and any steel plate used for hot pressing can be used, with no particular limitation on its composition.

[0155] However, as a non-limiting example, the base steel plate may contain, by weight percent: carbon (C): 0.02-0.60%, silicon (Si): 0.001-2.000%, aluminum (Al): 0.001-1.000%, manganese (Mn): 0.1-4.0%, phosphorus (P): less than 0.050%, sulfur (S): less than 0.0200%, nitrogen (N): less than 0.0200%, titanium (Ti): 0-1.0000%, niobium (Nb): 0-1.0000%, vanadium (V): 0-1.0000%, boron (B): 0-0.0100%, chromium (… Cr: 0-1.00%, Mo: 0-1.00%, Tungsten: 0-1.00%, Copper: 0-1.0%, Nickel: 0-1.0%, Antimony: 0-1.00%, Tin: 0-1.00%, Calcium: 0-0.10%, Magnesium: 0-0.10%, Cobalt: 0-1.00%, Arsenic: 0-1.00%, Zirconium: 0-1.00%, Bismuth: 0-1.00%, Rare Earth Elements (REM): 0-0.3%, Balance Fe and other unavoidable impurities.

[0156] In the above alloy composition, C and Mn can be added to ensure the strength of the steel. Si not only has a deoxidizing effect but also helps reduce the segregation of Mn and other elements in the base steel plate. Al also has a deoxidizing effect. It should be noted that P, S, N, etc., are elements that inevitably mix into the steel during the manufacturing process, but are not limited to these. In addition, considering the target properties of the final product, Ti, B, Cu, Mo, Cr, Ni, V, Ca, Nb, Sn, W, Sb, Mg, Co, As, Zr, Bi, REM, etc., can be added in addition to the above composition. This is obvious to those skilled in the art.

[0157] The alloy composition of the base steel plate according to one embodiment of the present invention will be described in more detail below.

[0158] Carbon (C): 0.02-0.60% Carbon (C) is an essential element for improving the strength of hot-formed components and can be included in an appropriate content. In one embodiment of the invention, when the C content is less than 0.02%, the target strength level cannot be guaranteed. On the other hand, when the C content exceeds 0.60%, the strength of the hot-rolled material obtained before cold rolling is too high, and there is a risk of a significant deterioration in rollability and a significant reduction in spot weldability when the hot-rolled material is cold-rolled. Therefore, in one embodiment of the invention, C can be included in a content of 0.02-0.60%. According to another embodiment of the invention, the C content can be less than 0.55%, and according to another embodiment, it can be less than 0.50%.

[0159] Silicon (Si): 0.001-2.000% Silicon (Si) can be added as a deoxidizer in steelmaking processes, effectively suppressing carbide formation in hot-formed components. In one embodiment of the invention, to achieve the above-mentioned effect, Si can be included at a content of 0.001% or more. However, when the silicon (Si) content exceeds 2.000%, excessive Si oxide formation may occur during the plating of the base steel sheet, potentially leading to poor plating performance. Therefore, in one embodiment of the invention, Si can be included at a content of 0.001-2.000%. According to another embodiment, the Si content can be 0.010% or more, and according to another embodiment, the Si content can be 1.500% or less.

[0160] Aluminum (Al): 0.001-1.000% Similar to Si, aluminum (Al) can be added as a deoxidizer in steelmaking processes, effectively suppressing carbide formation in hot-formed components. In one embodiment of the invention, to achieve the above-mentioned effect, Al can be included at a content of 0.001% or more. However, when the Al content exceeds 1.000%, excessive Al oxide formation may occur during the plating of the base steel sheet, potentially leading to poor plating performance. Furthermore, from the perspective of suppressing excessive temperature rise during high-temperature heat treatment for hot forming, the Al content can be 1.000% or less. Therefore, in one embodiment of the invention, Al can be included at a content of 0.001-1.000%. According to another embodiment, the Al content can be 0.005% or more, and according to another embodiment, the Al content can be 0.900% or less.

[0161] Manganese (Mn): 0.1-4.0% Manganese (Mn) not only has a solid solution strengthening effect, but can also be added to reduce the critical cooling rate required to ensure the martensitic phase during the manufacture of hot-formed components. In one embodiment of the invention, to fully obtain the above-mentioned effects, Mn can be included in a content of 0.1% or more. However, when the Mn content exceeds 4.0%, the strength of the hot-rolled material increases excessively, which may lead to a risk of reduced cold-rollability during subsequent cold rolling, and also results in poor spot weldability. Therefore, in one embodiment of the invention, Mn can be included in a content of 0.1-4.0%. According to another embodiment of the invention, the Mn can be 3.5% or less, and according to another embodiment, the Mn can be 3.0% or less.

[0162] Phosphorus (P): below 0.050% Phosphorus (P) is an element that inevitably gets mixed in during steel manufacturing, and it is advantageous to control its content as low as possible. In one embodiment of the invention, when the P content is below 0.050%, it does not hinder the assurance of the expected physical properties, and therefore its upper limit is limited to 0.050%. According to another embodiment of the invention, the P may be included in a content of 0.040% or less, or 0.030% or less. In addition, when the P content in the steel is reduced excessively, there is a risk of a significant increase in manufacturing costs; therefore, taking this into consideration, its lower limit can be limited to 0.001% or more.

[0163] Sulfur (S): below 0.0200% Sulfur (S) is an element that is unavoidably introduced during steel manufacturing. When the S content is too high, it can impair the bending properties, impact characteristics, and weldability of hot-formed components. Therefore, in one embodiment of the present invention, the S content can be limited to below 0.0200%. However, if the S content in the steel is reduced excessively, there is a risk of a significant increase in manufacturing costs. Therefore, taking this into consideration, its lower limit can be limited to above 0.0001%.

[0164] Nitrogen (N): below 0.0200% Nitrogen (N) is an element that is inevitably introduced during steel manufacturing. When the N content is too high, the slab becomes more susceptible to cracking during continuous casting, and the impact characteristics of hot-formed components may deteriorate. Therefore, in one embodiment of the present invention, the N content can be limited to below 0.0200%. However, if the N content in the steel is reduced excessively, there is a risk of a significant increase in manufacturing costs. Therefore, taking this into consideration, its lower limit can be limited to above 0.0001%.

[0165] Titanium (Ti): 0-1.0000%, Niobium (Nb): 0-1.0000%, and Vanadium (V): 0-1.0000% Titanium (Ti), niobium (Nb), and vanadium (V) combine with nitrogen in steel to form nitrides, thereby inhibiting the formation of boron nitrides (BN), thus improving the hardenability of the steel. Furthermore, grain refinement through the formation of fine precipitates effectively improves resistance to hydrogen embrittlement. In one embodiment of the invention, when the content of each of Ti, Nb, and V exceeds 1.0000%, the above effects will saturate, potentially leading to increased manufacturing costs. In one embodiment of the invention, the addition of Ti, Nb, and V is not mandatory. However, to achieve the above effects, these elements can be included in a content of 0.0001% or more.

[0166] Boron (B): 0-0.0100% Adding only a small amount of boron (B) can not only improve the hardenability of steel, but also segregate at the original austenite grain boundaries, effectively suppressing the brittleness of hot-pressed components caused by the segregation of P and / or S grain boundaries. In one embodiment of the invention, when the B content exceeds 0.0100%, the effect of adding B reaches saturation, and brittleness may occur during hot rolling. Therefore, in one embodiment of the invention, B can be included at a content of less than 0.0100%. According to another embodiment of the invention, the B can be included at a content of less than 0.0080% or less, or less than 0.0050%. In one embodiment of the invention, the addition of B is not mandatory, but when B is added to obtain the above-mentioned effects, it can be included at a content of more than 0.0001%.

[0167] Chromium (Cr): 0-1.00%, Molybdenum (Mo): 0-1.00%, and Tungsten (W): 0-1.00% Chromium (Cr), molybdenum (Mo), and tungsten (W) can be selectively added to improve the hardenability of steel, enhance strength through precipitation strengthening, and refine grain size. In one embodiment of the invention, the effect saturates when the content of each element exceeds 1.00%, which may lead to increased manufacturing costs.

[0168] Copper (Cu): 0-1.0% and Nickel (Ni): 0-1.0% Copper (Cu) forms fine precipitates in steel to improve its strength, and therefore can be added to achieve this effect. Adding Cu alone may cause hot brittleness, so to prevent this problem, nickel (Ni) can be added together as needed. In one embodiment of the invention, when the content of Cu and Ni each exceeds 1.0%, there is a significant increase in manufacturing costs.

[0169] Antimony (Sb): 0-1.00% and Tin (Sn): 0-1.00% Antimony (Sb) and tin (Sn) have the effect of suppressing the formation of oxides that may occur in the surface grains of hot-rolled steel with added Si and / or Al. That is, Sb and Sn can be selectively added to suppress dent defects caused by oxides forming at the grain boundaries on the surface of hot-rolled steel during annealing of cold-rolled steel. In one embodiment of the present invention, when the content of Sb and Sn each exceeds 1.00%, not only will the manufacturing cost increase significantly, but they will also dissolve at the grain boundaries in the slab state, which may cause edge cracks in the coil during subsequent hot rolling. Therefore, according to one embodiment of the present invention, when adding Sb and Sn, their respective contents can be limited to 1.00% or less.

[0170] Calcium (Ca): 0-0.10%, Magnesium (Mg): 0-0.10%, Cobalt (Co): 0-1.00%, Arsenic (As): 0-1.00%, Zirconium (Zr): 0-1.00%, and Bismuth (Bi): 0-1.00%. In one embodiment of the present invention, considering the target physical properties of the final product, the above-mentioned elements may be additionally included. However, if the content of Ca and Mg exceeds 0.10% and the content of Co, As, Zr and Bi exceeds 1.00%, the manufacturing cost will increase significantly. Therefore, the content of each element can be limited.

[0171] Rare earth elements (REM): 0-0.3% Rare earth elements (REMs) play a role in controlling the activity of Fe within steel, and therefore can be selectively added to control the thickness of the Fe oxide scale formed on the surface of the steel sheet during hot forming. In one embodiment of the invention, when the REM content exceeds 0.3%, the ability to control Fe activity is lost, potentially leading to a deterioration in surface quality. Therefore, according to one embodiment of the invention, the content of REM can be limited to below 0.3%.

[0172] The purpose of this invention is to provide a coated steel sheet for hot pressing, which may include a coating on one or both sides of the base steel sheet, wherein the coating may be an aluminum-based coating.

[0173] In one embodiment of the invention, the aluminum-based coating formed on at least one side of the base steel plate may be a coating with aluminum (Al) as the main element. As an example, the aluminum-based coating may, by weight percent, contain silicon (Si): 5.0-11.0%, iron (Fe): less than 10.0%, with the balance being aluminum (Al) and unavoidable impurities. Such an aluminum-based coating will be described in detail later, but it can be formed by immersing the base steel plate in an aluminum-based molten plating bath, and it is well known that the composition of the aluminum-based coating is determined by the composition within the aluminum-based molten plating bath.

[0174] The silicon (Si) in the aluminum plating layer not only lowers the melting point of the plating bath but also prevents over-alloying during the high-temperature heating of hot forming. Therefore, the Si content can be 5.0% or more. However, when the Si content exceeds 11.0%, the melting point of the plating bath may increase sharply, leading to a surge in the amount of slag (Ash) generated in the plating bath.

[0175] The iron (Fe) can exist as an impurity in the plating bath at a content of approximately 4.0% or less. Furthermore, Fe is an element present in the base steel sheet that dissolves into the coating during the plating process, thus being included in the aluminum-based coating. Therefore, the aluminum-based coating can contain less than 10.0% Fe. When the Fe content in the aluminum-based coating exceeds 10.0%, an excessive Al-Fe alloy phase will form, increasing the likelihood of coating peeling.

[0176] According to one example of the present invention, in addition to the above-described components, the aluminum-based coating may also contain other elements commonly found in coatings. Examples of these elements may be selected from one or more of Mg, Mn, Cr, Cu, Mo, Ni, Sb, Sn, Ti, Ca, and Sr.

[0177] The following describes in detail a method for manufacturing a hot-pressed coated steel sheet according to another aspect of the present invention. However, it should be noted that the following method for manufacturing the coated steel sheet is merely an example; the coated steel sheet of the present invention does not necessarily have to be manufactured using this method. Any manufacturing method that satisfies the scope of the claims of the present invention can be used to implement various embodiments of the present invention without any problem.

[0178] According to one embodiment of the present invention, a coated steel sheet for hot pressing can be obtained by a process including the following steps: preparing a base steel sheet; forming an aluminum-based coating on one or both sides of the base steel sheet to obtain a coated steel sheet; and performing a leveling rolling process on the coated steel sheet.

[0179] In one embodiment of the present invention, the base steel plate used to obtain the coated steel sheet for hot pressing can be the base steel plate described above, and its composition is not particularly limited. It is hereby stated that the above content is used instead.

[0180] According to one embodiment of the present invention, a base steel plate is loaded into a hot-dip galvanizing apparatus, and then a coating can be formed on one or both sides of the base steel plate through hot-dip galvanizing treatment. As an example, when an aluminum-based coating is used as the coating, the hot-dip galvanizing treatment can be a hot-dip aluminum plating method in which the base steel plate is immersed in a molten aluminum plating bath for plating. In this case, the temperature of the molten aluminum plating bath can be set to the temperature range of conventional aluminum plating, and as a non-limiting example, it can be carried out in the temperature range of 620-680°C.

[0181] In one embodiment of the invention, the molten aluminum plating bath is a plating bath with aluminum (Al) as the main component. As an example, the plating bath may contain 5.0-11.0% by weight of silicon (Si). In this way, by adding Si, effects such as improving the fluidity of the molten liquid and inhibiting the diffusion of Al into the base steel plate during plating can be obtained.

[0182] As another example, in addition to Si, it may contain less than 4.0% iron (Fe), and may further contain one or more of Mg, Mn, Cr, Cu, Mo, Ni, Sb, Sn, Ti, Ca, and Sr.

[0183] In one embodiment of the present invention, the coating weight during hot-dip aluminizing can be 60-100 g / m² based on a single side. 2 When the coating amount is less than 60 g / m 2 At this stage, there may be a risk of reduced corrosion resistance, but when the coating amount exceeds 100g / m², the corrosion resistance may decrease. 2 Weldability will decrease, and during the high-temperature heating of thermoforming, unalloyed Al may frequently stick to the rollers inside the heating furnace.

[0184] Furthermore, in one embodiment of the present invention, after the aluminizing, an alloying heat treatment step may be performed. The alloying heat treatment step is not particularly limited and can be achieved by online heating of the coated steel sheet (hot-dip aluminized steel sheet) obtained by hot-dip aluminizing while it is in motion. As an example, when performing alloying heat treatment by online heating, the heating temperature range can be 670-900°C, and the holding time can be 1-20 seconds. Coated steel sheets that undergo further alloying treatment in this way can be called alloyed hot-dip aluminized steel sheets.

[0185] In one embodiment of the present invention, the coated steel sheet having the aluminum coating can be subjected to a flat rolling process.

[0186] In one embodiment of the invention, the leveling rolling process of the coated steel sheet can be performed using rolls with a surface having Ra of 2.0-8.0 μm and RPc of 46-120 peaks / cm, with a reduction force of 100-500 tons. That is, during the leveling rolling process of the coated steel sheet, the conditions of the roll surface and the reduction force are controllable conditions for the surface state of the aluminum-based coated steel sheet according to one embodiment of the invention. The Rt and RPc of the coated steel sheet are affected not only by the Ra and RPc of the roll surface during leveling rolling, but also by the reduction force applied by the rolls.

[0187] In other words, on the coated surface of the hot-pressed steel sheet according to one embodiment of the present invention, in order to satisfy the above-mentioned relationship 1 while achieving sufficient values ​​for Rt and RPc, the Ra value of the roll surface during the leveling rolling can be limited to 2.0-8.0 μm, and the RPc value can be limited to a range of 46-120 peaks / cm. Furthermore, when leveling rolling is performed using rolls with this surface, rolling can be carried out with a reduction force of 100-500 tons.

[0188] Hereinafter, a hot-pressed molded component and its manufacturing method according to another aspect of the present invention will be described.

[0189] In one embodiment of the present invention, the hot-pressed forming component can be obtained by hot-pressing a steel sheet for hot pressing, wherein the steel sheet for hot pressing can be a steel sheet according to one embodiment of the present invention.

[0190] According to one embodiment of the present invention, a hot-pressing steel sheet includes a base steel sheet and an aluminum-based coating on at least one side of the base steel sheet, the aluminum-based coating having the characteristic that the Rt and RPc of its surface are controlled. Similarly, the Rt and RPc of the coating surface of the hot-pressed component obtained from this hot-pressing steel sheet can be controlled within a specific range.

[0191] In one embodiment of the invention, the maximum surface roughness (Rt) of the coating surface of the hot-pressed component can be 6.0-26.0 μm. Furthermore, according to one embodiment of the invention, the RPc (peaks / cm), representing the number of peaks per unit length, of the coating surface of the hot-pressed component can be 60-130 peaks / cm. Hot-pressed components with such surface-controlled coatings can exhibit excellent coating adhesion and wear resistance.

[0192] When the Rt value of the plating surface of a hot-pressed component according to one embodiment of the present invention is less than 6.0 μm or the RPc value is less than 60 peaks / cm, sufficient plating adhesion may be difficult to expect. On the other hand, when the Rt value of the plating surface of the hot-pressed component exceeds 26.0 μm or the RPc value exceeds 130 peaks / cm, it means that the Rt and RPc values ​​of the plating surface of the steel sheet for hot pressing are too high. In this case, the plating is easily damaged during the hot forming process due to friction with the mold, which may lead to mold sticking due to adhesive wear.

[0193] Furthermore, the inventors of this invention conducted repeated and in-depth research on conditions that can improve the coating adhesion and frictional properties of hot-pressed components. The results showed that the desired goal can be achieved by controlling the relationship between the coating thickness and the surface roughness (Rt) of the hot-pressed component. In particular, the inventors discovered that the coating thickness and surface roughness of the hot-pressed component affect the physical properties, such as coating adhesion and surface appearance, obtained through high-temperature molding. Therefore, the relationship between the coating thickness and the maximum roughness (Rt) of the hot-pressed component was re-examined. This will be described in detail below.

[0194] According to one embodiment of the present invention, the coating surface of the hot-pressed component can satisfy the following relationship 2.

[0195] [Relationship 2] 40.0≤T+(Rt / 2)≤57.0 (The unit of Equation 2 is μm, and T represents the thickness of the coating.) When the value of Equation 2 is less than 40.0, the coating adhesion of the hot-pressed component may deteriorate. On the other hand, when the value of Equation 2 exceeds 57.0, the coating may have been damaged due to friction with the mold during the hot-pressing process, potentially leading to mold sticking due to adhesive wear.

[0196] In one embodiment of the present invention, the coating thickness (T) of the hot-pressed component, representing T in Equation 2, can be in the range of 30.0-50.0 μm. Here, the thickness range is based on a single side. When the coating thickness of the hot-pressed component is less than 30.0 μm, the corrosion resistance may deteriorate. Furthermore, to satisfy Equation 2, the Rt value must be too large, which can cause the coating to break due to friction with the mold during hot forming, leading to mold sticking problems caused by adhesive wear. On the other hand, when the coating thickness exceeds 50.0 μm, although it is beneficial to improve corrosion resistance, it is difficult to fully alloy the coating within the specified heat treatment time, resulting in reduced productivity. In addition, there is a problem of Al sticking easily on the rollers in the heating furnace.

[0197] Thus, the surface properties of the hot-pressed component according to one embodiment of the present invention are controlled, resulting in excellent frictional characteristics. As an example, the hot-pressed component may have a coefficient of friction of 0.50 or less.

[0198] In one embodiment of the present invention, the aluminum coating of the hot-pressed component is alloyed during the high-temperature heating process of hot pressing, and can be an Al-Fe alloy composed of a total Al and Fe content of 89% or more (including 100%).

[0199] In one embodiment of the present invention, the base steel plate of the hot-pressed component, being formed after high-temperature heat treatment, can have a hard microstructure. As an example, the base steel plate can have a microstructure with a combined area fraction of martensite and bainite of more than 90%, and may also include pearlite, ferrite, etc., as other microstructures.

[0200] Furthermore, there is no particular limitation on the manufacturing method of the hot-pressed forming component according to one embodiment of the present invention. It can be manufactured as is well known in the prior art by heating the hot-pressed forming steel plate to a temperature above the austenitizing temperature, holding it, and then performing the forming process while rapidly cooling it.

[0201] However, as an example of the present invention, after obtaining a slab using a coated steel sheet for hot pressing according to an embodiment of the present invention, the slab can be heated to a temperature range of 860-970°C and held for 3-15 minutes. After hot pressing the slab that has been heated and held as described above, a cooling step is performed at a cooling rate of at least a critical cooling rate to manufacture the desired hot-pressed component. As a non-limiting example, the cooling can be performed at a cooling rate of 30°C / second or higher.

[0202] Hereinafter, the molding apparatus and the molding method using the second aspect of the present invention will be described.

[0203] According to one embodiment of the present invention, an apparatus and method are provided for forming a bracket having a curved portion and a flange using high-strength steel material, as well as a battery housing bracket formed by the apparatus and method, that is, forming a battery housing bracket that could not previously be formed using high-strength steel.

[0204] In one embodiment of the present invention, the high-strength steel material may be the aforementioned hot-pressed coated steel sheet, and may have the aforementioned alloy composition. Furthermore, the material may be manufactured using the aforementioned manufacturing method.

[0205] Figure 3 and Figure 4 A molding apparatus according to one embodiment of the present invention is shown. Specifically, Figure 3 An exploded perspective view of a molding apparatus according to one embodiment of the present invention is shown. Figure 4 A side view of a molding apparatus according to one embodiment of the present invention is shown. In this embodiment, the molding apparatus is shown centered on the appearance of the mold.

[0206] like Figure 3As shown, a molding apparatus according to one embodiment of the present invention includes: a pad A-200; a mold A-300 disposed on the outer side of the pad A-200 in a first direction 2; and a punch A-100 disposed on the lower part of the pad A-200, and including a body having a first punch forming portion to a fifth punch forming portion (A-120, A-130, A-140, A-150, A-160). Although Figure 3 and Figure 4 Not shown, but according to one embodiment of the present invention, the forming apparatus is a hot stamping forming apparatus, wherein the inner sides of the punch A-100 and the mold A-300 are provided with cooling water flow paths (A-170, A-370) (see reference). Figure 10 This allows the material to be cured through heat treatment during or after molding.

[0207] Pad A-200 and die A-300 are connected to the upper die of the press, and punch A-100 is connected to the lower die of the press. Material is formed while pad A-200 and die A-300 move vertically (in the third direction, 4) towards punch A-100. Although not shown, pad A-200 and die A-300 can move independently or relative to each other in the vertical direction. For example, an elastic member can be installed on the upper part of pad A-200, allowing pad A-200 and die A-300 to move together. After pad A-200 is formed, the elastic member causes only die A-300 to move downwards relative to pad A-200.

[0208] The punch A-100 can be configured to simultaneously form two supports. Therefore, it includes two forming portions corresponding to the curved portions of the supports. Specifically, when viewed in the first direction 2, the punch A-100 continuously includes, on the horizontal plane, a straight first punch forming portion A-110, a curved second punch forming portion A-120 having a forming portion curvature radius (Rp), a straight third punch forming portion A-130, a curved fourth forming portion A-140 having the forming portion curvature radius (Rp), and a straight fifth punch forming portion A-150 along the second direction 3 perpendicular to the first direction 2. A support portion A-160 for supporting material before forming is provided on the outer side of the first forming portion and the fifth forming portion A-150.

[0209] The first and fifth punch forming parts (A-110, A-150) have an overall structure that is inclined toward the third punch forming part A-130. The third punch forming part A-130 has a structure that is parallel to the horizontal plane at its center. The second and fourth punch forming parts (A-120, A-140) have a structure that bends to connect the first and fifth punch forming parts (A-110, A-150) with the third punch forming part A-130.

[0210] Centered on the third punch forming part A-130, the first punch forming part and the second punch forming part (A-110, A-120) have a symmetrical structure with the fourth punch forming part and the fifth punch forming part (A-140, A-150). Therefore, a bracket is formed with the second punch forming part A-120 as the center, and another bracket is formed with the fourth punch forming part A-140 as the center.

[0211] The first punch forming part A-110 includes: a first extension surface forming part A-111, which extends along a third direction 4 to form supports A-20 (see reference) on both sides of the first direction 2. Figure 1 The flanges (A-21, A-23; see reference) Figure 2 The first main body molding part A-113, which molds the main body A-23 of the bracket A-20 (see reference). Figure 2 It is disposed at the lower part of the pad A-200; and the first curved surface forming part A-112 has a bending radius of curvature (r) between the first extension surface forming part A-111 and the first main body forming part A-113.

[0212] The second punch forming section A-120 and the third punch forming section A-130 further include: a second extension surface forming section and a third extension surface forming section (A-121, A-131), wherein the second extension surface forming section and the third extension surface forming section (A-121, A-131) extend along the third direction 4 to form the flanges (A-21, A-22) of the support A-20 on both sides of the first direction 2; a second body forming section and a third body forming section (A-123, A-133), wherein the second body forming section and the third body forming section (A-123, A-133) form the main body A-23 of the support A-20 and are disposed at the lower part of the pad A-200; and the second curved surface forming part and the third curved surface forming part (A-122, A-132), the second curved surface forming part and the third curved surface forming part (A-122, A-132) having the bending radius of curvature (r) between the second extended surface forming part A-121 and the second main body forming part A-113, and between the third extended surface forming part A-131 and the third main body forming part A-133. At this time, the third main body forming part A-133 and the support part A-160 can be parallel to the horizontal plane.

[0213] The fourth and fifth punch forming parts (A-140, A-150) have a structure symmetrical to the first and second punch forming parts (A-110, A-120). Therefore, the fourth and fifth punch forming parts (A-140, A-150) also include the fourth and fifth extension surface forming parts (A-141, A-151), the fourth curved surface forming part and the fifth curved surface forming part (A-142, A-152), and the fourth and fifth main body forming parts A-143.

[0214] Additionally, pad A-200 includes a first pressure surface to a fifth pressure surface (A-210, A-220, A-230, A-240, A-250) having shapes corresponding to the first to fifth main body forming portions (A-113, A-123, A-133, A-143) of punch A-100. Pad A-200 applies pressure to the upper part of punch A-100, initially shaping the material into a curved portion. Pad A-200 may have a length in the first direction 2 from the length corresponding to the third main body forming portion A-133 to the third extension surface forming portion A-131.

[0215] Mold A-300 is disposed on both sides of the pad A-200 in a first direction and has a structure for forming flanges (A-21, A-22). In this embodiment, mold A-300 may be disposed on both sides to form flanges (A-21, A-22) formed on both sides of the support A-20, but is not limited thereto, and may be disposed on only one side. The two sides of mold A-300 are symmetrical about the pad A-200, therefore the description will focus on one side of mold A-300.

[0216] When viewed in the first direction 2, mold A-300 corresponds to the first to fifth forming sections (A-110, A-120, A-130, A-140, A-150) of punch A-100, including a straight first mold forming section A-310, a curved second mold forming section A-320 with a mold bending radius of curvature (Rd), a straight third mold forming section A-330, a curved fourth mold forming section A-340 with the aforementioned mold bending radius of curvature (Rd), and a straight fifth mold forming section A-310. The first to fifth mold forming sections (A-310, A-320, A-330, A-340, A-350) are connected by a vertical plane A-360.

[0217] Similar to the punch A-100, the first mold forming part and the second mold forming part (A-310, A-320) and the fourth mold forming part and the fifth mold forming part (A-340, A-350) in the mold A-300 have a symmetrical structure with the third mold forming part A-330 as the center.

[0218] The first mold forming part A-310 is adjacent to the punch A-100 and includes: a first mold curved surface forming part A-311, which is formed as a curved surface at a position relatively close to the punch A-100 in the first direction; and a first planar forming part A-312, which is located at a position relatively far from the punch A-100.

[0219] Similarly, the second to fifth mold forming sections (A-320, A-330, A-340, A-350) include the second to fifth mold curved surface forming sections (A-321, A-331, A-341, A-351) and the second to fifth planar forming sections (A-322, A-332, A-342, A-352). The closer the curved surface of the first to fifth mold curved surface forming sections (A-311, A-321, A-331, A-341, A-351) is to the punch A-100, the higher its height.

[0220] In this embodiment, when viewed in the first direction 2, the bending radius of curvature (Rd) in the second mold forming part and the fourth mold forming part (A-320, A-340) refers to the radius of curvature of the upper part (A-321a, A-341a) of the second surface forming part and the fourth surface forming part (A-321, A-341) that is closest to the punch A-100.

[0221] like Figure 4 As shown, in this embodiment, when the mold A-300 forms the flange, the first mold forming part and the fifth mold forming part (A-310, A-350) are configured to contact the material first, the third mold forming part A-330 next, and the second mold forming part and the fourth mold forming part (A-320, A-340) finally form the flange. Through this sequential forming, the material between the second mold forming part and the fourth mold forming part (A-320, A-340) and the second punch forming part and the fourth punch forming part (A-120, A-140) is stretched / contracted while being fixed, thereby preventing wrinkles or tears from occurring during the forming process.

[0222] Specifically, when the third main body forming part A-133 and the upper part A-331a of the third mold forming part A-330 are placed on the same plane a, when viewed in the first direction 2, the first main body forming part A-113 is located above the upper part A-311a of the first mold forming part A-310 c, and the second main body forming part A-123 is located below the upper part A-321a of the second mold forming part A-320 b. The symmetrical fourth and fifth mold forming parts (A-340, A-350) are also in the same relationship as the fourth and fifth main body forming parts (A-143, A-153).

[0223] That is, when the third mold forming part A-330 starts to flange the material, the first mold forming part A-310 is already flange forming, while the second mold forming part A-320, which is the bending part, has not yet started forming.

[0224] In this embodiment, the length lp of the third main body forming part A-133 is longer than the length ld of the third mold forming part A-330, and the bending radius of curvature (Rp) of the forming part of the second main body forming part A-123 is configured to be smaller than the mold bending radius of curvature (Rd) of the second mold forming part A-320, thereby achieving the above relationship.

[0225] Since the bending radius of curvature (Rd) of the mold is larger than the bending radius of curvature (Rp) of the forming part, the center of the bending radius of curvature (Rd) of the mold can be located at the center of the second direction 3 of the third mold forming part A-330. Therefore, the centers of the bending radius of curvature (Rd) of the second mold forming part A-320 and the fourth mold forming part A-340 can be located at the same position, but are not limited to this.

[0226] At this time, when viewed in the first direction, the angle (θ) at which the extensions of the virtual tangents at both ends of the fourth punch forming part A-143 intersect can be 90° or more, specifically 95-135°, and the same applies to the second punch forming part A-123.

[0227] Furthermore, according to one embodiment of the present invention, the forming apparatus achieves a structure that is difficult to achieve by stamping high-strength steel of 1200MPa and above in the past through hot stamping and the above structure. The bending radius of curvature (Rp) of the forming part and the bending radius of curvature (r) can satisfy 25mm≤Rp(mm)+r(mm)≤30mm.

[0228] The bracket produced by the forming apparatus can be used for battery casings as described above. However, when the radius of curvature in the battery casing is large, ineffective space is created. Therefore, the bending radius of curvature (r) that is actually allowed to form flanges in the battery casing is less than 10 mm. Furthermore, when the bending radius of curvature (r) is less than 3 mm, even hot-stamped steel with a strength of 1200 MPa or higher is difficult to form. Even if the bending radius of curvature (r) is 3 mm, whether it can be formed depends on the bending radius of curvature (Rp) of the forming part. This will be explained again when describing the bracket for battery casings.

[0229] Figures 5 to 11 A molding method according to one embodiment of the present invention, Figure 5 To illustrate a flowchart of a molding method according to one embodiment of the present invention, Figure 6 A plan view showing the material incorporated into a molding apparatus according to one embodiment of the present invention, Figure 7 A schematic perspective view is provided to illustrate a single molding step in a molding method according to an embodiment of the present invention. Figure 8 , Figure 9a and Figure 9b A schematic perspective view, another perspective view, and a front view are shown in a molding method according to one embodiment of the present invention, illustrating a secondary molding step. Figure 10 To illustrate a front view of the cooling step in a molding method according to an embodiment of the present invention, Figure 11 A perspective view illustrating the finishing step in a molding method according to an embodiment of the present invention.

[0230] The molding method according to another aspect of the present invention can be performed by the above-described molding apparatus, and therefore also refers to... Figure 3 Please provide an explanation.

[0231] According to one embodiment of the present invention, the molding method includes: a material placement step S110, in which a heated material A-400, which is longer than a punch A-100 having a molding portion in a first direction 2, is placed on the punch A-100; a primary molding step S120, in which the material A-400 is molded according to the shape of the main molding portion (A-113, A-123, A-133, A-143) of the punch A-100 by a pad A-200 located above the punch A-100; a secondary molding step S130, in which the material A-400 is molded to have the shape of the molding portion of the punch A-100 by a mold A-300 located outside the pad A-200 in the first direction 2; a cooling step S140, in which the material is cooled by at least one of the punch and the mold to give the material a martensitic structure; and a finishing step S150, in which the cooled molded article is cut into a support shape.

[0232] Material placement step S110 involves adding material to the forming device and placing it on the punch A-100. At this point, the material is a steel plate, and it is placed on the punch A-100 in an austenitic state, i.e., heated to a temperature above AC3, so that structural changes can occur during or after forming. The material can be hot-stamped steel, such as 22MnB5 steel.

[0233] In one embodiment of the present invention, the material may be the above-mentioned hot-pressed coated steel sheet, and may have the above-mentioned alloy composition.

[0234] Furthermore, in this invention, to form two supports in a single molding process, material A-400 includes a notch A-410 at its center in the second direction 3, facing the center of the material and formed on both sides. The notch A-410 can concentrate deformation during molding, thereby preventing cracks from forming in areas outside the notch A-410.

[0235] like Figure 7 As shown, the one-time forming step S120 is the step of bending and forming material A-400 by pad A-200 after placing material A-400. Pressure is applied to material A-400 on the upper part of punch A-100 by pad A-200, thereby forming material A-400.

[0236] like Figures 8 to 9a and Figure 9bAs shown, the secondary forming step S130 is the step of flange forming the bent material using mold A-300, and the step of deforming the material A-400 that is not in contact with the pad A-200 in the first forming process using mold A-300 and pressure is applied to the portion of the material A-400 that is not in contact with the pad A-200. At this time, as... Figure 4 In the secondary forming step S130, the mold A-300 sequentially forms the material in the second direction 3, starting with the edge, then the center, and finally the middle portion between the center and the edge. The bent portion of the material A-400 formed in the first forming step, namely the second punch forming portion and the fourth punch forming portion (A-120, A-140), is formed last, thereby forming a flange on the material A-400. At this time, the shapes of the punch A-100 and the forming portion of the mold A-300 have been determined. Figure 3 and Figure 4 An explanation was provided.

[0237] Cooling step S140 is a step of cooling material A-400 during or after the forming process. Cooling fluid is circulated through cooling channels (A-170, A-370) formed on at least one of the punch and the die to cool the austenitic material A-400, transforming the austenitic structure into a martensitic structure, thereby making material A-400 a high-strength steel with a tensile strength of 1200 MPa or higher. In this embodiment, the cooling channels (A-170, A-370) are formed simultaneously on both the punch A-100 and the die A-300. If the austenitic-to-martensitic phase transformation can be achieved, the cooling channels (A-170, A-370) can be provided on only one of them. If necessary, cooling channels (A-170, A-370) can also be provided on the pad A-200.

[0238] After completing the cooling step S140, proceed to the trimming step S150, which involves cutting the formed material A-400 along the cutting line A-420, so that only the portions corresponding to the two supports are retained. The two supports are cut with the second punch forming portion and the fourth punch forming portion (A-120, A-140) of the punch A-100 as the center.

[0239] According to one embodiment of the present invention, the forming method can form a bracket having a bend and a flange using high-strength steel. Furthermore, by applying a hot stamping forming method, springback of the high-strength steel during the forming process can be prevented, and forming errors such as wrinkles or thinning caused by forming the flange of the bend can be prevented.

[0240] Figure 12 A perspective view of a bracket manufactured by a molding method according to an embodiment of the present invention.

[0241] Figure 12 The support A-20 has a main body A-23 and flanges (A-21, A-22), and is bent as a whole with a bending radius of curvature (Rp) of the forming part. At this time, the flanges (A-21, A-22) are connected to the main body A-23 via a curved surface A-24 that bends towards the main body A-23 with a bending radius of curvature r. Among the main body A-23, flanges (A-21, A-22), and the curved surface A-24 between them, the surface formed with the bending radius of curvature (Rp) of the forming part can be called the forming surface.

[0242] Figure 13 The diagram shows the thickness reduction rate distribution of a molded article produced by a molding method according to one embodiment of the present invention (Embodiment 1-1). Figure 14 The figure shows the thickness reduction rate distribution of Comparative Example 1-1 produced by other molding methods. Figure 15 The middle shows Figure 13 and Figure 14 The thickness reduction rate distribution of the molded product at the cross-section.

[0243] The thickness reduction rate distribution chart is used to represent material A-400 (see Figure 6 The graph shows how the thickness of material A-400 changes after molding. The thickness reduction rate is obtained by subtracting the thickness of the corresponding position of the support A-20 from the initial thickness (t_initial) of material A-400 and then dividing by the initial thickness (t_initial). A positive thickness reduction rate indicates a decrease in thickness, while a negative thickness reduction rate indicates an increase in thickness.

[0244] Figure 13 The implementation plan is to use Figure 3 The forming device was manufactured using 22MnB5 steel (heated to have a martensitic structure) and the cooling rate was adjusted. The tensile strength of the support was 1500 MPa. At this time, the material thickness was 1.2 t, the bending radius of curvature (r) was 5 mm, and the bending radius of curvature (Rp) of the forming part was 22 mm.

[0245] like Figure 13 , Figure 15 As shown, the thickness of the main body A-23 in the bracket A-20 is no different from the initial thickness (tinitial). Therefore, the average thickness (taverage) of the main body A-23 of the bracket A-20 can be regarded as the initial thickness (tinitial) of the material A-400. The thickness reduction rate can be regarded as the average thickness (taverage) of the main body A-23 minus the thickness at each position and then divided by the average thickness (taverage).

[0246] Comparative Example 1-1 uses the same forming apparatus to form martensitic steel with a tensile strength of 1500 MPa as the material.

[0247] like Figure 15 As shown, it can be confirmed that when a support is manufactured using the molding apparatus and molding method according to one embodiment of the present invention (Embodiment 1-1), the maximum value of the thickness reduction rate, i.e., the minimum value of the thickness (T), is achieved. 最低 The thickness reduction rate of the thinnest part does not exceed 0.2, while in Comparative Example 1-1, the thickness reduction rate of the thinnest part exceeds 0.2. When the thickness reduction rate exceeds 0.2 and becomes larger, a height difference will appear in the flanges (A-21, A-22), resulting in reduced sealing when manufacturing the battery casing.

[0248] In addition, such as Figure 15 As shown, even though the support primarily elongates due to bending, shrinkage still occurs in certain areas. When this shrinkage triggers buckling, it can lead to material breakage. In the support of a molding method according to an embodiment of the present invention, the maximum thickness (T) at the curved surface... 最高 No thickness reduction rate below -0.3 is generated at the location, so it can be confirmed that stable molding can be achieved even in the bending part.

[0249] However, it can be seen that in comparative example 1-1, at the maximum thickness (T) 最高 At the location where a thickness reduction rate of -0.8 occurs, buckling occurs in this section. This buckling can develop into cracks, which not only impair the structural performance of the battery casing but may also allow moisture to seep in through the cracks. Therefore, the bracket in Comparative Example 1-1 cannot be used in battery casings. To maintain a seal, it is advantageous to maintain a thickness reduction rate of -0.4 or higher in the bent portion.

[0250] Furthermore, the sum of the bending radius of curvature (Rp) and the bending radius of curvature (r) of the formed portion needs to reach 25 mm or more to achieve molding. First, when the bending radius of curvature (r) is less than 3 mm, even with the molding apparatus and method according to one embodiment of the present invention, it is difficult to mold a bracket applicable to a battery casing. Even if flange molding is possible due to a bending radius of curvature (r) of 3 mm, the flange of the bent portion cannot be well molded when the bending radius of curvature (Rp) of the formed portion is less than 22 mm. Additionally, when the bending radius of curvature (r) and the bending radius of curvature (Rp) of the formed portion increase, although molding itself is not difficult, the curvature radius of the battery casing increases, creating ineffective space and resulting in a loss of practicality. Therefore, the sum of the bending radius of curvature (Rp) and the bending radius of curvature (r) of the formed portion of the bracket applied to the battery casing is preferably less than 30 mm.

[0251] Furthermore, the angle (θ) at which the extensions of the virtual tangents at both ends of the molded surface in bracket A-20 intersect can be between 95° and 135°. When the angle (θ) is less than 95°, even if the conditions for the bending radius of curvature (Rp) and bending radius of curvature (r) of the molded part are met, good molding cannot be achieved. When the angle (θ) exceeds 135°, the battery casing needs to be constructed from angles exceeding octagonal angles, resulting in ineffective space that the approximately cuboid-shaped battery cells cannot fill, thus losing practicality.

[0252] in addition, Figure 16 The image shows a side view illustrating the molding method of comparative examples 1-2. Figure 17 A perspective view of a molded article produced by the molding method of Comparative Examples 1-2 is shown.

[0253] Figure 16 The molding method follows the same sequence as the molding method of the present invention, but in the secondary molding step S130, the flange is not formed in the order of edge-center-bent portion in the second direction 3, but is formed by a mold A-300 configured to form in the order of center-bent portion-edge. The mold A-300 in Comparative Examples 1-2 is configured to have an upper part A-301a with the lowest center, and forming is performed sequentially outward.

[0254] Even so, hot stamping forming process is still used during molding, such as Figure 17 As shown, a folded area B will appear, thus creating a bracket that cannot be used as a battery casing.

[0255] The above description focuses on the embodiments of the present invention, but the present invention is not limited thereto, and it is natural that various modifications and implementations can be made.

[0256] Hereinafter, a hot stamping formed part according to the third aspect of the present invention will be described.

[0257] Figure 18 A perspective view of a molded component according to an embodiment of the present invention is shown. Figure 19 A front view of a molded component according to an embodiment of the present invention is shown.

[0258] According to one embodiment of the present invention, a hot-stamped forming component includes: a first wall B-110 extending along a first direction Y; and a second wall B-120 extending along a direction intersecting the first wall B-110, wherein a curvature portion B-160 is formed between the first wall B-110 and the second wall B-120, and an angle between any line perpendicular to the first direction (a line parallel to the Z direction) and the second wall B-120 is 0° or more and 5° or less, and the first wall B-110, the second wall B-120 and the curvature portion B-160 are integrally formed.

[0259] According to one embodiment of the present invention, a hot-stamped component includes a first wall B-110, a second wall B-120, and a curved portion B-160 located between the first wall B-110 and the second wall B-120. The component is integrally formed in the order of the first wall B-110, the curved portion B-160, and the second wall B-120.

[0260] The hot-stamped part is characterized by including a first wall B-110 formed parallel to a first direction, a curved portion B-160 bent from the first wall B-110, and a second wall B-120 connected to one end of the curved portion B-160, all integrally formed.

[0261] Assuming there exists an arbitrary line perpendicular to the first direction, the angle between the second wall B-120 and this arbitrary line can be greater than 0° and less than 5°.

[0262] With the increasing demand for lightweight and safer vehicles, components made of high-strength steel are being mass-produced. However, high-strength steel has poor bending properties, making it difficult to manufacture components with small radii of curvature.

[0263] Hot stamping is a manufacturing method that involves heating a sheet metal blank, stamping it into the desired shape, and then cooling it while the mold is closed to produce high-strength molded parts. This hot stamping method, which uses high-temperature forming, benefits from the excellent elongation of over 50% at the high temperature, allowing for the crack-free forming of parts with small radii of curvature. Therefore, it can ensure the shape of parts that cannot be achieved with cold stamping for ultra-high strength.

[0264] One embodiment of the present invention relates to a molded component B-10 integrally formed by hot stamping, comprising a first wall B-110, a curved portion B-160, and a second wall B-120, wherein the angle between the second wall B-120 and any of the aforementioned lines is 0° or more and 5° or less, which is a smaller angle than that of existing components. Therefore, the first wall B-110 and the second wall B-120 have near-right-angle shapes, thereby maximizing the usability of the space enclosed by the first wall B-110 and the second wall B-120.

[0265] According to one embodiment of the present invention, the first wall B-110, the second wall B-120 and the curvature portion B-160 can be integrally formed by sheet metal processing.

[0266] The first wall B-110, the curved portion B-160, and the second wall B-120 can be integrally formed by hot stamping, using a single sheet or multiple sheets joined together along the thickness direction as a blank. Integrating them by hot stamping not only facilitates processing but also prevents processing problems or stress concentration-induced damage at welded joints. Furthermore, it allows for the production of a formed component B-10 with relatively high tensile strength.

[0267] In one embodiment of the present invention, the sheet material may be the above-mentioned hot-pressed coated steel sheet and may have the above-mentioned alloy composition.

[0268] According to one embodiment of the present invention, the radius of curvature (r) of the curvature portion B-160 is greater than or equal to 0.5 mm, and the ratio of the thickness (t) of the plate to the radius of curvature (r), i.e., the ultimate bending (r / t), can be formed to be less than 2.5.

[0269] The ratio (r / t) of the sheet thickness (t) to the radius of curvature (r) before processing is usually determined by the ultimate bending value of the raw material. Ultimate bending can be considered as a value expressed as the maximum radius of curvature that will not produce cracks relative to the material thickness. The sheet thickness (t) is generally preset before processing, so when the radius of curvature decreases and becomes less than the ratio (r / t) that can be formed in the sheet, cracks will appear on the formed part B-10.

[0270] According to one embodiment of the invention, the ratio (r / t) of the sheet thickness (t) to the radius of curvature (r) can be less than 2.5. In contrast, the ultimate bending limit of existing ultra-high strength materials with a tensile strength of 1500 MPa is known to be 2.5 or higher. For example, this means that the minimum radius of curvature for forming a 1500 MPa-grade ultra-high strength component with a material thickness of 1.0 mm is 2.5 mm or higher. However, according to the invention, when forming with ultra-high strength, the ratio (r / t) can still have a value less than 2.5, thus allowing ultra-high strength materials with a tensile strength of 1500 MPa to form products with a ratio (r / t) less than 2.5. Therefore, the molded component according to one embodiment of the invention can be a component with excellent formability and high space utilization. According to one embodiment of the present invention, the molded component includes: a third wall B-130 and a fourth wall B-140, which are parallel to the first direction; and a fifth wall B-150, which is connected to the third wall B-130 and the fourth wall B-140, the third wall B-130 extending from the second wall B-120, and the first wall B-110 to the fifth wall B-150 can be integrally molded.

[0271] According to the hot stamping process, a hat-shaped form with multiple walls can be formed in one step, thus exhibiting excellent formability.

[0272] As an example, a third wall B-130 and a fourth wall B-140 parallel to the first direction can be formed. The first wall B-110 and the fourth wall B-140 may have the same height in the direction perpendicular to the first direction, but are not limited to this. Furthermore, the height of the third wall B-130 may also be different. A fifth wall may be located between the third wall B-130 and the fourth wall B-140. The second wall B-120 is connected to the third wall B-130 via a first connecting part B-170, the third wall B-130 is connected to the fifth wall B-150 via a second connecting part B-180, and the fifth wall B-150 is connected to the fourth wall B-140 via a third connecting part B-190. Therefore, the first to fifth walls B-150, the curvature portion B-160, and the first to third connecting parts B-170 can be integrally formed using sheet metal processing.

[0273] The first connecting portion B-170 to the third connecting portion B-190 can be formed to have the same radius of curvature as the curvature portion B-160, and the radius of curvature can also have all the characteristics of the curvature portion B-160 of the first wall B-110 and the second wall B-120. However, it is not limited to this shape.

[0274] According to one embodiment of the present invention, the tensile strength of the molded part can be 1300-2100 MPa.

[0275] The ultra-high tensile strength mentioned is typically about 1500 MPa. According to the present invention, molded parts with tensile strengths of about 1300-2100 MPa, which can be considered to be at the high-strength to ultra-high-strength level, can be manufactured. Since the formability becomes excellent due to hot stamping, the molded part according to one embodiment of the present invention can be manufactured as a single piece, and a part with a relatively small radius of curvature can be manufactured while simultaneously achieving ultra-high tensile strength.

[0276] Furthermore, taking advantage of its excellent formability at high temperatures, 1800MPa and 2000MPa grade hot stamping steels can also be formed into parts with small radii of curvature as described above. Therefore, according to the present invention, it is also possible to manufacture formed parts with small radii of curvature having tensile strengths of 1700MPa to 1900MPa, and further 1900MPa to 2100MPa.

[0277] Furthermore, in the microstructure constituting the molded component B-10, the area fraction of martensite can be 98% or more. Because martensite, as a high-strength hard phase, constitutes the majority of the area fraction in the molded component B-10 according to the present invention, an ultra-high tensile strength level as described above can be achieved.

[0278] As an example, the formed part is formed of martensite with an area fraction of more than 98%, and may also include trace amounts of ferrite or bainite.

[0279] According to one embodiment of the present invention, the molded component further includes a third wall B-130 that is parallel to the first direction and connected to the second wall B-120. The length from the first wall B-110 to the third wall B-130 in a direction perpendicular to the first direction is defined as the wall height (hw). When the angle between any line perpendicular to the first direction and the second wall B-120 is defined as the wall angle (θw), the following relationship 3 can be satisfied.

[0280] [Relationship 3] hw≤13.4 θw+182.4 Where hw is in mm and θw is in degrees, the left and right sides are calculated after being dimensionless.

[0281] The molded parts that satisfy the above relationship 3 and are processed by hot stamping can be manufactured with excellent quality without defects such as cracks.

[0282] As shown in Table 1 below, when the above formula is satisfied, it can be seen that the formability is excellent.

[0283] [Table 1] Comparative Examples 2-1 to 2-4, except for the wall height shown in the table above, are formed in the same manner as Invention Examples 2-1 to 2-4. However, in the molding results, the comparative examples show molding defects such as cracks.

[0284] Figure 20a The figure is for explanation purposes in the same manner as in Invention Example 2-1. Figure 20b This is a diagram used to explain the comparison under the conditions of Example 2-1. (Comparison) Figure 20a and Figure 20b It can be seen that, in Comparative Example 2-1, cracks marked in red are produced on the upper part of the second wall B-120 or the fifth wall B-150, and some areas are marked in yellow as parts where there is a risk of cracking.

[0285] Figure 21a The figures are for explanation purposes in the same manner as those in Examples 2-3 of the invention. Figure 21b This diagram is for explanation under the conditions of Comparative Examples 2-3. Comparison Figure 21a and Figure 21b It is evident that in Comparative Examples 2-3, cracks marked in red appear in the lower part of the second wall B-120 or the fifth wall B-150, and some areas are indicated in yellow as parts at risk of developing cracks. In contrast, although some parts of Invention Example 2-3 are marked in yellow as parts at risk of developing cracks, no cracks have occurred.

[0286] The battery pack module of another aspect of the present invention will now be described.

[0287] The following battery pack modules include the molded components described above, and the description of the molded components is based on the above description.

[0288] Figure 22 A diagram illustrating a battery pack module according to one embodiment of the present invention is provided. Figure 23 The diagram illustrates the space utilization when placing a battery pack by showing a partial cross-section of the battery pack module. (a) shows the case where the radius of curvature of the hot-stamped part is small, and (b) shows the case where the radius of curvature is larger than that in (a).

[0289] According to one embodiment of the present invention, a battery pack module B-1 includes: a battery housing B-20, which surrounds a battery pack; a base B-30, which is located at the lower part of the battery housing B-20 and connected to the battery housing B-20 to form a space for placing the battery pack; and a hot-stamped component B-10, which is disposed transversely through the interior of the battery housing B-20 and connected to the battery housing B-20 and the base B-30.

[0290] The battery casing B-20 is a structure that surrounds the sides of the battery pack. The base B-30 can be a regular sheet metal or a structure with bends or grooves to accommodate the battery pack, as needed.

[0291] As an example, to prevent collisions, a reinforcement B-40 may be further included on the outer side of the battery housing B-20.

[0292] As an example, the hot-stamped component B-10, acting as a crossbeam, can enhance the rigidity of the battery frame to withstand the impact of a collision, and can be housed inside the battery casing B-20.

[0293] As an example, multiple hot-stamped components B-10 can be arranged at certain intervals within the battery casing B-20.

[0294] The battery pack is located in the space formed between the base B-30, the battery housing B-20 and the crossbeam. The battery pack module B-1 includes the battery pack and is used to stably place the battery in the vehicle body.

[0295] The battery pack incorporates molded components with a smaller radius of curvature and higher tensile strength than existing products, which can improve the rigidity of the battery pack module B-1 itself, thereby preventing fires caused by battery impact damage.

[0296] In addition, multiple crossbeams are usually set inside the battery housing B-20, so the increased space utilization can increase the size of the battery pack. Therefore, when the battery pack module B-1 has the same volume, it can provide the effect of increasing battery capacity.

[0297] As an example used as a crossbeam, compared to Figure 23 In embodiment (a), the radius of curvature r1 of the lower end of the hot-stamped part B-10a in form 2-1 is such that when Figure 23 When the radius of curvature r2 of the lower end of the hot stamping part B-10b in embodiment 2-2 of (b) is larger, it can be confirmed by comparing the remaining space after the battery pack b is placed, i.e., the gap. Figure 23 The gap g2 in (b) is much larger than Figure 23 From the gap g1 in (a), it can be seen that as the radius of curvature (r) increases, the space that cannot be used for mounting the battery pack b is formed to be larger.

[0298] Furthermore, the smaller the radius of curvature (r), the higher the space utilization rate, indicating that mounting multiple crossbeams within the same battery module B-1 has greater efficiency.

[0299] The hot stamping forming component of the fourth aspect of the present invention will be described below.

[0300] Figure 24 A perspective view of a stamped part according to an embodiment of the present invention is provided. Figure 25 A perspective view is provided to illustrate a stamped part according to another embodiment of the present invention. Figure 26 (a) is a graph showing the relationship between a preset length and a preset height of a stamped part according to an embodiment of the present invention. Figure 26 (b) is a graph illustrating the relationship between a predetermined length and a predetermined height of a stamped part according to another embodiment of the present invention. Furthermore, Figure 27 (a) illustrates an example of the deformation force applied to a stamped part manufactured by existing manufacturing methods. Figure 27 (b) illustrates an example of the deformation force applied to a stamped part manufactured using a manufacturing method according to an embodiment of the invention.

[0301] Reference Figure 24 and Figure 25 According to an embodiment of the present invention, the stamped parts (C-10, C-10') can be manufactured by stamping a metal sheet. In this case, the stamped parts (C-10, C-10') can be manufactured using a hot stamping method.

[0302] The stamped parts (C-10, C-10') include: a flat portion C-110, which is a portion having a flat shape without being stamped; and a deformable portion C-120, which is a portion having a shape that protrudes in one direction through stamping. Multiple deformable portions C-120 can be formed. In this case, the flat portion C-110 can be disposed among multiple deformable portions C-120.

[0303] Based on the figure, the deformable part C-120 can be convex in the upward direction (+Z). In this case, the deformable part C-120 may include a top plate part C-121, a longitudinal wall part C-122, and a boundary part C-123.

[0304] The top plate portion C-121 can be the upper end of the deformable portion C-120 extending along the first direction. The first direction can be, for example, a direction parallel to the length direction Y of the stamped part (C-10, C-10').

[0305] The longitudinal wall portion C-122 can be a side wall portion of the deformed portion C-120 extending along the second direction. The second direction can be a direction different from the first direction described above. As an example, the second direction can be a direction inclined at a predetermined angle relative to the first direction. As another example, the second direction can be a direction perpendicular to the first direction, and can be a direction parallel to the vertical direction Z in the figure. Furthermore, the vertical direction Z can be parallel to the height direction of the deformed portion C-120.

[0306] The longitudinal wall portion C-122 can be continuous with the top plate portion C-121. More specifically, the upper end of the longitudinal wall portion C-122 can be continuous with one side end of the top plate portion C-121. A pair of such longitudinal wall portions C-122 can be provided. The pair of longitudinal wall portions C-122 are respectively continuous with both sides of the top plate portion C-121, thereby forming the two side wall portions of the deformable portion C-120.

[0307] The portion (hereinafter, shoulder) C-121a where the side end of the top plate portion C-121 connects to the upper end of the longitudinal wall portion C-122 can be shaped like a round arc with a first radius of curvature. Furthermore, the shoulder C-121a can bend outward toward the outside of the deformable portion C-120.

[0308] Boundary portion C-123 can be the boundary between deformable portion C-120 and flat portion C-110, which are continuous along the length Y direction of the stamped part (C-10, C-10'). One end of boundary portion C-123 can be continuous with the lower end of longitudinal wall portion C-122, and the other end of boundary portion C-123 can be continuous with one end of flat portion C-110. In this case, the other end of flat portion C-110 can be continuous with boundary portion C-123 provided in another deformable portion C-120. A pair of such boundary portions C-123 can be provided, and can be configured to be continuous with the lower ends of a pair of longitudinal wall portions C-122 respectively.

[0309] The boundary portion C-123 can be an arc shape with a second radius of curvature. The boundary portion C-123 can be concave and bent inward toward the deformed portion C-120. In this case, the second radius of curvature can be the same as or similar to the first radius of curvature.

[0310] As described above, the deformable portion C-120 can be a shape in which the boundary portion C-123, the longitudinal wall portion C-122, the top plate portion C-121, the longitudinal wall portion C-122, and the boundary portion C-123 are sequentially arranged along its length direction Y. Therefore, the deformable portion C-120 can have a hat shape or a similar shape.

[0311] Multiple deformable portions C-120 as described above can be provided. More specifically, at least three deformable portions C-120 can be provided. In this case, a flat plate portion C-110 can be provided between two adjacent deformable portions C-120. At this time, two adjacent deformable portions C-120 can be continuous through the flat plate portion C-110 located at their center.

[0312] Therefore, the stamped parts (C-10, C-10') can be arranged in a row with three or more deformable parts C-120 and multiple flat parts C-110 along the length direction Y. In this case, flat parts C-110 can be provided on the outer sides of both sides of the stamped parts (C-10, C-10') based on the aforementioned length direction Y, but it is not limited to this.

[0313] The deformable part C-120 can be formed at a preset height h. At this time, the preset height h is the height of the deformable part C-120, which can refer to the length from the lower surface of the flat plate part C-110 to the upper surface of the top plate part C-121.

[0314] Two adjacent deformable portions C-120 can be separated by a preset length w along the length direction Y. The preset length w can refer to the length of the flat plate portion C-110 measured with the length direction Y as a reference. In this case, the preset length w can be measured with the flat plate portion C-110 positioned between the two adjacent deformable portions C-120 as a reference.

[0315] like Figure 24 As shown, according to one embodiment of the present invention (hereinafter, embodiment 3-1), the stamped forming part C-10 may include three deformable portions C-120. Therefore, the stamped forming part C-10 of embodiment 3-1 may include at least two flat portions C-110, such that the flat portions C-110 are respectively located between the three deformable portions C-120.

[0316] like Figure 25 As shown, according to another embodiment of the present invention (Embodiment 3-2), the stamped forming part C-10' may include four or more deformable portions C-120. Therefore, the stamped forming part C-10 of Embodiment 3-1 may include at least three flat portions C-110, such that the flat portions C-110 are disposed among the four or more deformable portions C-120.

[0317] Furthermore, although the accompanying drawings only show the case where four deformable portions C-120 are provided in the stamped part C-10', the present invention is not limited thereto. Although not shown in the drawings, in other embodiments, five or more deformable portions C-120 may be formed in the stamped part C-10', and in this case, the upper limit of the number of deformable portions C-120 is not limited.

[0318] Reference Figure 26 and Figure 27 In existing hot stamping forming methods, the deformed portion C-120 is formed first, and then a separate flat metal sheet is attached to the lower end of the formed deformed portion C-120. In this case, when the number of deformed portions C-120 to be formed increases, such as... Figure 27 As exemplarily shown in (a), during the manufacturing process, forces (deformation forces) are concentrated on the longitudinal wall portion C-122 connecting the flat metal plates and its surrounding portion. Figure 27 (a) A1 and B1]. Therefore, there is a disadvantage that cracks or other damage may occur in the deformed portion C-120 of the stamped part. In order to prevent this problem, the distance between the connected deformed portions C-120 needs to be increased, but the size of the manufactured stamped parts (C-10, C-10') is limited, so there is a problem that the number of deformed portions C-120 that can be included is also limited.

[0319] Therefore, in one embodiment of the present invention, by utilizing the relationship between the height of the deformable portion C-120 (a preset height h) and the spacing between two adjacent deformable portions C-120 (a preset length w), a stamped part (C-10, C-10') that can prevent damage to the deformable portion C-120 caused by hot stamping is provided. In this case, the "relationship between the preset height h and the preset length w" can be determined based on the number of deformable portions C-120 formed on the stamped part (C-10, C-10').

[0320] In the stamped part C-10 of embodiment 3-1 according to the present invention, since three deformable parts C-120 are formed, the relationship between the "preset height h" of the deformable part C-120 and the "preset length w" between two adjacent deformable parts C-120 can be defined by the following formula (1).

[0321] w 最小 ≤w≤114.85e 0.0455h ...Formula (1) Where w can refer to the preset length of embodiment 3-1, and h can refer to the preset height of embodiment 3-1. Furthermore, w 最小 It can refer to the minimum value of the preset length w in implementation mode 3-1 (i.e., the minimum spacing).

[0322] like Figure 26 The diagram in (a) and Figure 27 As shown in (b), when the distance between the three deformable parts C-120 included in the stamped part C-10 (the preset length w) satisfies formula (1), the deformable part C-120 and its surrounding parts can be minimized during the hot stamping process. Figure 27 In (b), damage such as cracks occurs in A2 and B2. At this point, the manufacturing method of the stamped part C-10 according to Embodiment 3-1 will be described in detail below.

[0323] Furthermore, in the stamped part C-10 of embodiment 3-2 according to the present invention, since more than four deformable parts C-120 are formed, the relationship between the "preset height h" of the deformable part C-120 and the "preset length w" between two adjacent deformable parts C-120 can be defined by the following formula (2).

[0324] w 最小 ≤w≤46.309e 0.105h …Formula (2) Where w can refer to the preset length of embodiment 3-2, and h can refer to the preset height of embodiment 3-2. Furthermore, w 最小 It can refer to the minimum value of the preset length in implementation form 3-2.

[0325] like Figure 26 The diagram in (b) and Figure 27 As shown in (b), when the distance between the three deformable parts C-120 included in the stamped part C-10 (the preset length w) satisfies formula (1), the deformable part C-120 and its surrounding parts can be minimized during the hot stamping process. Figure 27 In part b, damage such as cracks occurs in A2 and B2. At this point, the manufacturing method of the stamped part C-10 according to embodiment 3-1 will be described in detail below.

[0326] Furthermore, in embodiments 3-1 and 3-2 described above, the preset length w can be 20 mm or more. That is, the minimum distance (w) between two adjacent deformable parts C-120 最小 The spacing can be 20mm. This can be the minimum required spacing to ensure the space for providing cooling holes (not shown) between the first pressurizing part C-210 and / or between the second pressurizing part C-410 and the intermediate pressurizing part C-300 in the die (C-200, C-400) in the manufacturing apparatus (C-20, C-20') of the following stamped parts (C-10, C-10').

[0327] Figure 28 A flowchart illustrating a method for manufacturing a stamped part according to one embodiment of the present invention. Figure 29 Schematic illustration of manufacturing Figure 24 The first step in the stamping process of the part. Figure 30 Schematic illustration of manufacturing Figure 24 The second step in the stamping process of the component. Figure 31Schematic illustration of manufacturing Figure 24 The third step in the stamping process of the part. Furthermore... Figure 32 Schematic illustration of manufacturing Figure 24 The fourth step in the stamping process of the component.

[0328] Reference Figures 28 to 32 The manufacturing apparatus C-20 for manufacturing the stamped part C-10 according to embodiment 3-1 may include a first die C-200, an intermediate pressure section C-300, and a second die C-400. In this case, one intermediate pressure section C-300 may be provided. At this time, with the vertical direction Z as the reference, the first die C-200 may be an upper die, and the second die C-400 may be a lower die.

[0329] The first mold C-200 and the second mold C-400 can be arranged opposite each other along the pressing direction -Z. The first mold C-200 can be located above the second mold C-400. In this case, the first mold C-200 can be mounted on an upper support platform (not shown) that can be lifted and driven. Therefore, the first mold C-200 can descend towards the second mold C-400 or rise away from the second mold C-400. Furthermore, the second mold C-400 can be mounted, for example, on a lower support platform (not shown), which is fixed and mounted on the bottom surface of the building where the manufacturing apparatus C-20 is installed.

[0330] The first die C-200 may include a first pressure section C-210. During stamping, the first pressure section C-210 can apply pressure to the upper surface of the metal sheet. The metal sheet may be made of the same material used to manufacture the stamped part C-10. Before stamping, the metal sheet may have a flat upper and lower surface, for example. In this case, the first pressure section C-210 may be configured to have a shape and dimensions corresponding to the upper surface of the deformable portion C-120 of the stamped part C-10 described above.

[0331] The manufacturing apparatus C-20 is for manufacturing the stamped part C-10 of Embodiment 3-1, and therefore can be provided with three first pressing parts C-210. At this time, the three first pressing parts C-210 can be spaced apart by a first distance. The first distance is the same as the preset length w mentioned above. Furthermore, the first mold C-200 can have a first flat surface C-220. The first flat surface C-220 can be provided between two adjacent first pressing parts C-210. The first flat surface C-220 can extend parallel to the length direction Y between two first pressing parts C-210 and connect to the first pressing parts C-210. As described above, since three first pressing parts C-210 are provided, at least two first flat surfaces C-220 can be provided.

[0332] Therefore, the first mold C-200 can be configured such that three first pressure parts C-210 are spaced apart from each other by a first distance (i.e., a preset length w) along the length direction Y, and a first flat part C-220 is provided between them to connect the first pressure parts C-210.

[0333] The second mold C-400 may include a second pressure part C-410 and a second flat part C-420a. At this time, the second pressure part C-410 may be formed to have a shape and size corresponding to the lower surface of the stamping part C-10.

[0334] Unlike the first mold C-200, the second mold C-400 may only have two second pressurizing parts C-410. In this case, the two second pressurizing parts C-410 may be arranged symmetrically along the length direction Y to the two first pressurizing parts C-210 located on both sides of the three first pressurizing parts C-210. Therefore, in the second mold C-400, the second pressurizing part C-410 may not exist in the region opposite to the central first pressurizing part C-210 of the three first pressurizing parts C-210 (hereinafter referred to as the central region).

[0335] Therefore, the second mold C-400 can be a single structure connected by two second pressing parts C-410 and a second flat part C-420a disposed therebetween. In this case, the flat part C-420a can have a through part C-420aa. When stamping the outer region of the metal sheet C-10A, the intermediate pressing part C-300 can be inserted into the through part C-420aa. The through part C-420aa can be formed by penetrating a portion of the flat part C-420a in the vertical direction Z. This through part C-420aa can have a cross-sectional shape and area corresponding to the shape and size of the intermediate pressing part C-300. Furthermore, each side of the first pressing part C-210 can further have a second-second flat part C-420b.

[0336] An intermediate pressure section C-300 can be disposed between the first die C-200 and the second die C-400. As shown in FIG38, the metal sheet C-10A, which is the object to be stamped, can be disposed on the lower side of the first die C-200. In this case, the intermediate pressure section C-300 can be located between the metal sheet C-10A and the second die C-400, so that when the first die C-200 descends, a portion of the lower surface of the metal sheet C-10A can be pressurized. The intermediate pressure section C-300 can be, for example, a pad for pressing the lower surface of the metal sheet C-10A for bending processing.

[0337] The intermediate pressure section C-300 can be located directly above the intermediate region of the second mold C-400. In this case, the intermediate pressure section C-300 can have the same shape as the second pressure section C-410. That is, the intermediate pressure section C-300 can have a shape and size corresponding to the lower surface of the stamped part C-10. During stamping, this intermediate pressure section C-300, together with the middle first pressure section C-210 of the three first pressure sections C-210, can press the metal sheet C-10A in the vertical direction, thereby forming the deformed part C-120 located in the middle.

[0338] The intermediate pressure section C-300 can be configured to be vertically movable. Therefore, during stamping, the intermediate pressure section C-300 can descend along the pressure direction -Z. Furthermore, after stamping is completed, the intermediate pressure section C-300 can rise in the opposite direction of the pressure direction Z. This rising of the intermediate pressure section C-300 can be achieved by an elastic member (not shown) provided in the intermediate pressure section C-300.

[0339] The "manufacturing method of stamped part C-10 according to embodiment 3-1" using the manufacturing apparatus C-20 described above can be as follows.

[0340] First, metal sheet C-10A can be supplied to manufacturing unit C-20 (S100). Before stamping begins, such as Figure 29 As shown, the metal plate C-10A can be positioned between the first mold C-200 and the intermediate pressure section C-300 (hereinafter referred to as the processing position). Alternatively, the metal plate C-10A can be supplied to the manufacturing apparatus C-20 while being heated by a separate heating device (not shown).

[0341] As an example, when the metal plate C-10A is in the processing position, it can be positioned such that the upper surface of the metal plate C-10A is in contact with the lower surface of the first mold C-200, or there is only a small gap between them. At this time, the second mold C-400 can be positioned symmetrically with the first mold C-200, separated by the metal plate C-10A and the intermediate pressure part C-300.

[0342] Furthermore, when the metal sheet C-10A is in the processing position (i.e., before stamping begins), the intermediate pressure part C-300 can be positioned above the second die C-400. Therefore, a height difference hi can exist between the intermediate pressure part C-300 and the second pressure part C-410. This height difference hi can refer to the distance from the upper surface of the second pressure part C-410 to the upper surface of the intermediate pressure part C-300. In this case, the height difference hi between the intermediate pressure part C-300 and the second pressure part C-410 can be less than the height of the stamped part C-10, i.e., the "preset height h". In this case, the height difference hi can be 65% or more of the preset height h. When the manufacturing apparatus C-20 is configured to have the height difference hi described above, the occurrence of damage such as cracks in the deformed part C-120 formed by stamping can be minimized.

[0343] Next, the metal sheet C-10A can be stamped into shape S200 in one pass through the first mold C-200 and the intermediate pressure section C-300. For example... Figure 30 As shown, the first mold C-200 can descend along the pressing direction -Z to press the upper surface of the metal plate C-10A. In this case, the first mold C-200 can descend to a position where the lower surface of the metal plate C-10A does not contact the second mold C-400. At this time, since the intermediate pressing part C-300 is set to be higher than the second pressing part C-410 by the height difference hi, only the intermediate pressing part C-300 is introduced into the first pressing part C-210, and the middle area of ​​the metal plate C-10A can be pressed. Therefore, only the middle area of ​​the metal plate C-10A can be stamped in the vertical direction by the middle first pressing part C-210 and the intermediate pressing part C-300 among the three first pressing parts C-210. Therefore, only the middle area of ​​the metal plate C-10A is bent, thereby forming a deformed part C-120.

[0344] Next, the metal sheet C-10A can be subjected to secondary stamping forming S300 through the first die C-200 and the second die C-400. After the first stamping forming in step S200, as... Figure 31 As shown, the first mold C-200 can further descend along the pressing direction -Z. During this process, with the intermediate pressing part C-300 and the intermediate region of the metal plate C-10A introduced into the intermediate first pressing part C-210, it can descend together with the first mold C-200. Therefore, the outer region of the metal plate C-10A can contact the upper surfaces of the two second pressing parts C-410.

[0345] Subsequently, as the first die C-200 continues to descend, the second pressure section C-410 is introduced into the first pressure section C-210, allowing pressure to be applied to the outer regions on both sides of the metal sheet C-10A. During this process, the intermediate pressure section C-300 can be accommodated within the through section C-420aa of the second die C-400. The outer regions on both sides of the metal sheet C-10A can be simultaneously stamped vertically by the two outer first pressure sections C-210 and the two outer second pressure sections C-410. Therefore, the outer regions on both sides of the metal sheet C-10A are bent, thereby further forming two deformed sections C-120.

[0346] Next, the first mold C-200 and the intermediate pressure section C-300 can return to their initial positions S400. Following the "step-by-step stamping" process described above in steps S200 and S300, as follows... Figure 32 As shown, the first die C-200 can rise in the opposite direction of the pressing direction -Z, +Z. During this process, the deformed part C-120 can separate from the first pressing part C-210. Furthermore, the intermediate pressing part C-300 can separate from the intermediate deformed part C-120 and return to its initial position. Therefore, it is possible to manufacture a stamped part C-10 with three deformed parts C-120 having a preset height h and spaced apart from each other by a preset length w.

[0347] Afterwards, the completed stamped part C-10 can be discharged from S500. After being discharged from the manufacturing unit C-20, the stamped part C-10 can be transported to the next processing or manufacturing process. Then, by supplying the next metal sheet C-10A, the above manufacturing method can be repeated.

[0348] Figure 33 Schematic illustration of manufacturing Figure 25 The first step in the stamping process of the part. Figure 34 Schematic illustration of manufacturing Figure 25 The second step in the stamping process of the component. Figure 35 Schematic illustration of manufacturing Figure 25 The third step in the stamping process of the part. Furthermore... Figure 36 Schematic illustration of manufacturing Figure 25 The fourth step in the stamping process of the component.

[0349] Reference Figure 28 and Figures 33 to 36The stamped part C-10 according to Embodiment 3-2 can be manufactured by the following manufacturing method. The manufacturing apparatus C-20' for the stamped part may include a first die C-200, an intermediate pressure section C-300, and a second die C-400. In this case, at least two intermediate pressure sections C-300 may be provided. In this case, most of the features of the first die C-200, the intermediate pressure section C-300, and the second die C-400 are the same as or similar to those in Embodiment 3-1 described above, so repeated descriptions are omitted.

[0350] Since the stamping part C-10' according to embodiment 3-2 has four or more deformable parts C-120, the first die C-200 can have four or more first pressing parts C-210. Hereinafter, for ease of explanation, the case with four first pressing parts C-210 spaced apart by a predetermined length w will be emphasized. In this case, two first pressing parts C-210 can be provided in the middle region of the first die C-200, and one first pressing part C-210 can be provided on each side of them as the center.

[0351] The second mold C-400 may have two second pressure sections C-410. At this time, the two second pressure sections C-410 may be arranged opposite to the two first pressure sections C-210 respectively provided on both sides of the first mold C-200.

[0352] When four first pressure-applying sections C-210 are provided, two intermediate pressure-applying sections C-300 can also be provided. In this case, the two intermediate pressure-applying sections C-300 can be arranged opposite to the two first pressure-applying sections C-210 located in the area between the first mold C-200. The intermediate pressure-applying sections C-300 are located between the first mold C-200 and the second mold C-400, as in the case described above.

[0353] Furthermore, in embodiment 3-2, the second planar portion C-420a of the second die C-400 can have two through portions C-420aa. Therefore, when the outer region of the metal sheet C-10A is stamped by the first die C-200 and the second die C-400, the two intermediate pressure portions C-300 can be respectively accommodated in each through portion C-420aa.

[0354] In the "manufacturing method of stamped part C-10' according to embodiment 3-2" using the manufacturing apparatus C-20' described above, steps S100, S200, S300, and S400 can be performed sequentially, similar to the manufacturing method of stamped part C-10 in embodiment 3-1. Since the specific manufacturing methods performed in each step are the same as or similar to those in embodiment 3-1, the differences will be emphasized in the explanation.

[0355] First, in step S100, as Figure 33 As shown, metal plate C-10' can be supplied to the aforementioned processing position. In this case, metal plate C-10A can be supplied to manufacturing apparatus C-20' while being heated by a separate heating device (not shown). When supplied to the processing position, the two intermediate pressure units C-300 can be located below the middle region of metal plate C-10'. At this time, the two intermediate pressure units C-300 can be set at the same height. In this case, the height difference hi between the intermediate pressure unit C-300 and the second pressure unit C-410 is the same as in embodiment 3-1.

[0356] Next, in step S200, as Figure 34 As shown, as the first mold C-200 descends, the intermediate pressure section C-300 is introduced into the two first pressure sections C-210 located in the middle region of the first mold C-200, thereby applying pressure to the middle region of the metal plate C-10'. Through the single stamping process described above, two deformable sections C-120 can be formed in the middle region of the metal plate C-10A.

[0357] Next, in step S300, as follows Figure 35 As shown, the first mold C-200 descends further, and the second pressing part C-410 can be introduced into the two first pressing parts C-210 respectively located in the outer region of the first mold C-200. Therefore, the outer region of the metal plate C-10' can be stamped in the vertical direction by the first pressing part C-210 and the second pressing part C-410. Through the secondary stamping forming step described above, two deformed parts C-120 can be further formed in the outer region of the metal plate C-10A.

[0358] Next, in step S400, as Figure 36 As shown, the first die C-200 can rise in the opposite direction of the pressing direction -Z, +Z. Therefore, the stamped part C-10', having completed the stamping process, can be separated from the first die C-200, the intermediate pressing section C-300, and the second die C-400. During this process, the two intermediate pressing sections C-300 rise, thus returning to their initial positions as described above during the processing.

[0359] Afterward, the completed stamped part C-10' is discharged from the manufacturing unit C-20', and then the next stamping process can begin as a new metal sheet C-10' is supplied.

[0360] In addition, when the number of deformed portions C-120 formed on the stamped part C-10' increases, the number of intermediate pressure portions C-300 can also be increased accordingly.

[0361] For example, although not shown in the accompanying drawings, when five deformed portions C-120 are formed on the stamped part C-10', the first die C-200 must have five first pressing portions C-210. Therefore, three intermediate pressing portions C-300 can be provided and arranged opposite to the three first pressing portions C-210 provided in the middle region of the first die C-200. In this case, the three intermediate pressing portions C-300 can be provided between the first die C-200 and the second die C-400.

[0362] Of the three intermediate pressure sections C-300, the middle intermediate pressure section (hereinafter referred to as the first intermediate pressure section C-300) can be positioned at the highest point. The remaining two intermediate pressure sections (hereinafter referred to as the second intermediate pressure sections C-300) can be positioned between the first intermediate pressure section C-300 and the second mold C-400. In this case, the two second intermediate pressure sections C-300 can be set to the same height. The height difference between the first intermediate pressure section C-300 and the second intermediate pressure section C-300 can be the same as or similar to the height difference hi between the intermediate pressure section C-300 and the second pressure section C-400.

[0363] In the configuration described above, a first stamping process can be performed using the first die C-200 and the first intermediate pressure section C-300. Upon completion of the first stamping process, or just before completion, the first die C-200 and the first intermediate pressure section C-300 descend further, allowing for a second stamping process using the first die C-200 and two second intermediate pressure sections C-300. This two-stage stamping process allows the middle region of the metal sheet C-10A to be formed first. Then, after the second stamping process is completed, or just before completion, the first die C-200 descends further, allowing for a third stamping process using the first die C-200 and the second die C-400 to form the outer region of the metal sheet C-10A.

[0364] As another example, although not shown in the accompanying drawings, when six deformed portions C-120 are formed on the stamped part C-10', the first die C-200 must have six first pressing portions C-210. Therefore, four intermediate pressing portions C-300 can be provided, and arranged opposite to the four first pressing portions C-210 provided in the middle region of the first die C-200. In this case, the four intermediate pressing portions C-300 can be provided between the first die C-200 and the second die C-400.

[0365] Of the four intermediate pressure units C-300, the two middle intermediate pressure units (hereinafter referred to as the first intermediate pressure units C-300) can be positioned at the highest point. The remaining two intermediate pressure units (hereinafter referred to as the second intermediate pressure units C-300) can be positioned between the first intermediate pressure units C-300 and the second mold C-400. In this case, the two first intermediate pressure units C-300 can be set to the same height. Furthermore, the two second intermediate pressure units C-300 can also be set to the same height. The height difference between the first intermediate pressure units C-300 and the second intermediate pressure units C-300 can be the same as or similar to the height difference hi between the intermediate pressure units C-300 and the second pressure units C-400.

[0366] In the configuration described above, a first stamping process can be performed using the first die C-200 and two first intermediate pressure sections C-300. Upon completion of the first stamping process, or just before completion, the first die C-200 and the first intermediate pressure sections C-300 descend further, allowing for a second stamping process using the first die C-200 and two second intermediate pressure sections C-300. This two-stage stamping process allows the middle region of the metal sheet C-10A to be formed first. Then, after the second stamping process is completed, or just before completion, the first die C-200 descends further, allowing for a third stamping process using the first die C-200 and the second die C-400 to form the outer region of the metal sheet C-10A.

[0367] Furthermore, when the number of deformable portions C-120 formed on the stamped part C-10' increases to seven or more, similar to the above situation, it is necessary to further increase the number of the first pressing portion C-210 and the intermediate pressing portion C-300. Therefore, the number of through portions C-420aa on the second die C-400 can also be increased. With the manufacturing apparatus configured in this way, by adding a stamping step, the middle region of the metal sheet C-10A can be stamped first, and then the outer region of the metal sheet C-10A can be stamped.

[0368] As described above, the stamped parts (C-10, C-10') and their manufacturing method S10 according to an embodiment of the present invention can be formed by providing an intermediate pressure section C-300 with a height difference hi between the upper and lower dies (C-200, C-400), and using three pressure sections (C-210, C-300, C-410) to stamp the metal sheet (C-10, C-10'). In this case, by first stamping the middle region of the metal sheet (C-10, C-10') and then sequentially stamping the outer regions, the deformation force during stamping can be prevented from concentrating at specific locations on the metal sheet (C-10, C-10'). Therefore, damage to the stamped parts (C-10, C-10') during manufacturing can be prevented, and the quality of the parts can be improved.

[0369] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing its technical concept or essential features. Therefore, the embodiments described above should be understood in all respects as exemplary and not limiting.

[0370] [Explanation of reference numerals in the attached figures] A-1: Side frame; A-10: Frame A-20: Bracket; A-21, A-22: Flange A-23: Main body; A-24: Curved surface A-100: Punch A-110, A-120, A-130, A-140, A-150: Forming sections of punches 1 to 5 A-111, A-121, A-131, A-141, A-151: First extension surface forming section to fifth extension surface forming section A-112, A-122, A-132, A-142, A-152: Surface forming section 1 to surface forming section 5 A-113, A-123, A-133, A-143: First main body molding section to fourth main body molding section A-200: Pad A-300: Mold A-310, A-320, A-330, A-340, A-350: Mold forming sections 1 to 5 A-311, A-321, A-331, A-341, A-351: Curved surface forming section of mold 1 to curved surface forming section of mold 5 A-312, A-322, A-332, A-342, A-352: Planar forming sections of mold 1 to mold 5 A-360: Vertical Plane A-400: Material; A-410: Notch B-1: Battery pack module; B-10: Hot-stamped components B-20: Battery casing; B-30: Base B-40: Reinforcing component; B-110: First wall B-120: Second Wall; B-130: Third Wall B-140: Fourth Wall; B-150: Fifth Wall B-160: Curvature section; B-170: First connecting section B-180: Second connecting part; B-190: Third connecting part b: Battery pack; r: Radius of curvature t: Plate thickness; θw: Wall angle hw: Wall height C-10, C-10': Stamped parts C-10A: Metal Plate C-110: Flat section C-120: Deformation section C-20, C-20': Stamping forming device C-200: First Mold C-210: First protrusion C-220: First Plane Section C-300: Intermediate Pressurization Section C-400: Mold 2 C-410: Second protrusion C-420: Second Plane Section Detailed Implementation The following detailed description is provided through examples. However, it should be noted that the following examples are merely illustrative and not intended to limit the scope of the invention. The scope of the invention is determined by the matters set forth in the claims and those reasonably deduced therefrom.

[0371] (Example) As the base steel sheet, a cold-rolled steel sheet for hot pressing and forming with the composition shown in Table 2 below was prepared. The base steel sheet was subjected to annealing heat treatment using conventional methods followed by hot-dip aluminizing. The composition of the plating bath, by weight percent, consisted substantially of 9.5% Si, less than 4.0% Fe, and the balance Al, and the plating bath temperature was set to 660°C. After plating, the coating adhesion was adjusted using an air knife, with one side as the reference. At this time, the adhesion of each coating layer was measured using the KS D 3544: 2002 sodium hydroxide-antimony trichloride hydrochloric acid peel weight method, and the values ​​are shown in Table 3 below.

[0372] Subsequently, using rolls with Ra and RPc values ​​as shown in Table 3, each coated steel sheet is subjected to leveling rolling with the pressing force shown in Table 3, thereby adjusting the coating surface condition of each coated steel sheet.

[0373] Subsequently, the coated steel sheets that have undergone the leveling and rolling process are heated and held in an atmospheric environment under the conditions shown in Table 4, followed by stamping and rapid cooling to obtain hot-pressed components. It was confirmed that the tensile strength of each obtained hot-pressed component is above 1000 MPa, and the internal structure is essentially composed of hard phases of martensite and bainite.

[0374] To confirm the surface characteristics of each coated steel sheet and hot-pressed component manufactured in the manner described above, the maximum roughness (Rt) and the number of peaks per unit length (RPc, peaks / cm) were measured for each coating surface. The Rt and RPc values ​​were measured at five locations according to JIS B 0301 standard, and their average values ​​were calculated and presented. The results for the coated steel sheets are shown in Table 3 below, and the results for the hot-pressed components are shown in Table 4. Furthermore, the coating thickness (T) of each hot-pressed component was measured at five locations at equal intervals using an optical microscope at 500x magnification, and then measured at another five locations at equal intervals using the same magnification. The average values ​​were calculated and presented.

[0375] In addition, the coating adhesion, friction coefficient, adhesive wear weight increase and alloying degree of each hot-pressed component were evaluated by the following methods, and the results are shown in Table 5.

[0376] First, regarding the coating adhesion rating, according to the GMW14829 method, after coating the obtained components, 1mm interval grid scratches are formed, and the rating is determined by tape peel evaluation. A rating below 0 is considered good.

[0377] For the coefficient of friction, each specimen heated and held under the heating conditions shown in Table 4 below was evaluated by strip drawing at 750°C, and the coefficient of friction (μ) was calculated according to the following formula.

[0378] μ=F D / (2F N ) Among them, F D F is the force that stretches the specimen. N The force applied to the specimen by the die during the friction process was 5 MPa. The tensile speed was 100 mm / s, and the tensile distance was 280 mm. Furthermore, the die was made of SKD11 tool steel with a chromium (Cr) surface treatment and a hardness of 58.2 ± 0.4 HRC. The die dimensions were 20 × 20 × 9 mm. 3 The sample is hexahedral in shape, with the ends of the surfaces that rub against the test piece rounded by 1.5 mm. To ensure the reliability of the measurements, the test was performed three times, and the average value was calculated.

[0379] For the increase in weight due to contact wear, the same method as for measuring the coefficient of friction was repeated 10 times. The weight of the residue adhering to the mold was then measured, and the difference in weight increase after the test relative to the weight before the test was calculated and shown.

[0380] For the degree of alloying, the following values ​​(average values) are shown: for each thermoformed component, samples were collected from any five locations, and the coating cross-section of each sample was observed with an optical microscope at 1000x magnification. The area of ​​complete alloying without residual Al coating in the entire coating area was calculated.

[0381] [Table 2] [Table 3] As shown in Table 3, it can be confirmed that the surface properties of the coated steel sheet obtained by meeting the requirements proposed in one embodiment of the present invention under the coating conditions and leveling rolling conditions meet the expected requirements of the present invention.

[0382] On the other hand, when the conditions for leveling the rolling rolls or the reduction rate conditions deviate from the scope of an embodiment of the present invention, at least one of the surface characteristics of the coating fails to meet the requirements.

[0383] [Table 4] [Table 5] As shown in Tables 4 and 5, it can be confirmed that the surface properties of the hot-pressed components obtained by hot-pressing the coated steel sheet with the expected surface properties of the present invention meet the requirements proposed in one embodiment of the present invention. Therefore, it can be seen that the coefficient of friction, coating adhesion, adhesive wear characteristics, and alloying characteristics of each hot-pressed component are all good or excellent.

[0384] On the other hand, when hot pressing is performed on a coated steel sheet that does not have the surface characteristics expected in this invention (comparative example), at least one of the surface characteristics of the obtained hot-pressed component fails to meet the requirements proposed in one embodiment of this invention.

[0385] Furthermore, these hot-pressed components failed to meet more than one of the physical properties shown in Table 5. Comparative Examples 1 and 2 had poor coefficients of friction and poor coating adhesion, while Comparative Examples 3 and 4 had poor adhesive wear characteristics.

[0386] The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Those skilled in the art can of course make modifications and implement it without changing the technical concept of the present invention as claimed in the claims.

Claims

1. A coated steel sheet for hot pressing, comprising a base steel sheet and an aluminum-based coating on one or both sides of the base steel sheet, wherein the maximum surface roughness (Rt) of the coating is 4.0-25.0 μm. The relationship between the amount of coating adhesion and Rt satisfies the following equation 1. [Relation 1] 27.0≤( / 3)+(Rt / 2)≤38.0 The unit of relation 1 is μm. This indicates the amount of coating adhered.

2. The coated steel sheet for hot pressing according to claim 1, wherein, The number of peaks per unit length (RPc) of the aluminum-based coating is 30-90 peaks / cm.

3. The coated steel sheet for hot pressing according to claim 1, wherein, The aluminum-based coating, by weight percent, comprises silicon (Si): 5.0-11.0%, iron (Fe): less than 10.0%, with the balance being aluminum (Al) and other unavoidable impurities.

4. The coated steel sheet for hot pressing according to claim 1, wherein, The base steel plate, by weight percent, contains carbon (C): 0.02-0.60% and silicon (Si): 0.001-2.000%, Aluminum (Al): 0.001-1.000%, Manganese (Mn): 0.1-4.0%, Phosphorus (P): below 0.050%, Sulfur (S): below 0.0200%, Nitrogen (N): below 0.0200%, Titanium (Ti): 0-1.0000%, Niobium (Nb): 0-1.0000%, Vanadium (V): 0-1.0000%, Boron (B): 0-0.0100%, Chromium (Cr): 0-1.00%, Molybdenum (Mo): 0-1.00%, Tungsten (W): 0-1.00% Composition of copper (Cu): 0-1.0%, nickel (Ni): 0-1.0%, antimony (Sb): 0-1.00%, tin (Sn): 0-1.00%, calcium (Ca): 0-0.10%, magnesium (Mg): 0-0.10%, cobalt (Co): 0-1.00%, arsenic (As): 0-1.00%, zirconium (Zr): 0-1.00%, bismuth (Bi): 0-1.00%, rare earth elements (REM): 0-0.3%, balance Fe and other unavoidable impurities.

5. A method for manufacturing a coated steel sheet for hot pressing, comprising the following steps: Prepare the foundation steel plate; An aluminum-based coating is formed on one or both sides of the base steel plate to obtain a coated steel plate; as well as The galvanized steel sheet is subjected to a leveling and rolling process. The leveling rolling process is carried out using rolls with a surface having Ra: 2.0-8.0μm and RPc: 46-120 peaks / cm, with a pressing force of 100-500 tons.

6. The method for manufacturing coated steel sheet for hot pressing according to claim 5, wherein, The step of forming an aluminum-based coating to obtain a coated steel sheet is to immerse the base steel sheet in an Al-based plating bath containing, by weight %: Si: 5.0-11.0%, Fe: less than 4.0%, with the balance being Al and other unavoidable impurities.

7. The method for manufacturing a coated steel sheet for hot pressing according to claim 5, wherein, The manufacturing method further includes the step of heating the plated steel sheet with the aluminum coating to a temperature range of 670-900°C for alloying heat treatment.

8. The method for manufacturing a coated steel sheet for hot pressing according to claim 5, wherein, The base steel plate, by weight percent, contains carbon (C): 0.02-0.60% and silicon (Si): 0.001-2.000%, Aluminum (Al): 0.001-1.000%, Manganese (Mn): 0.1-4.0%, Phosphorus (P): below 0.050%, Sulfur (S): below 0.0200%, Nitrogen (N): below 0.0200%, Titanium (Ti): 0-1.0000%, Niobium (Nb): 0-1.0000%, Vanadium (V): 0-1.0000%, Boron (B): 0-0.0100%, Chromium (Cr): 0-1.00%, Molybdenum (Mo): 0-1.00%, Tungsten (W): 0-1.00% Composition of copper (Cu): 0-1.0%, nickel (Ni): 0-1.0%, antimony (Sb): 0-1.00%, tin (Sn): 0-1.00%, calcium (Ca): 0-0.10%, magnesium (Mg): 0-0.10%, cobalt (Co): 0-1.00%, arsenic (As): 0-1.00%, zirconium (Zr): 0-1.00%, bismuth (Bi): 0-1.00%, rare earth elements (REM): 0-0.3%, balance Fe and other unavoidable impurities.

9. A thermoformed component comprising a base steel plate and an aluminum-based coating with a thickness (T) of 30.0-50.0 μm formed on the base steel plate. The maximum surface roughness (Rt) of the coating is 6.0-26.0 μm. The relationship between the thickness of the coating and Rt satisfies the following equation 2. [Relationship 2] 40.0≤T+(Rt / 2)≤57.0 The unit of Equation 2 is μm, and T represents the thickness of the coating.

10. The thermoformed component according to claim 9, wherein, The number of peaks per unit length (RPc) of the aluminum-based coating is 60-130 peaks / cm.

11. The thermoformed component according to claim 9, wherein, The aluminum coating is composed of an Al-Fe alloy with a total Al and Fe content of 89% by weight or more.

12. The thermoformed component according to claim 9, wherein, The coefficient of friction of the component is below 0.

50.

13. The thermoformed component according to claim 9, wherein, The base steel plate, by weight percent, contains carbon (C): 0.02-0.60% and silicon (Si): 0.001-2.000%, Aluminum (Al): 0.001-1.000%, Manganese (Mn): 0.1-4.0%, Phosphorus (P): below 0.050%, Sulfur (S): below 0.0200%, Nitrogen (N): below 0.0200%, Titanium (Ti): 0-1.0000%, Niobium (Nb): 0-1.0000%, Vanadium (V): 0-1.0000%, Boron (B): 0-0.0100%, Chromium (Cr): 0-1.00%, Molybdenum (Mo): 0-1.00%, Tungsten (W): 0-1.00%, Copper Composition of Cu: 0-1.0%, Ni: 0-1.0%, Sb: 0-1.00%, Sn: 0-1.00%, Ca: 0-0.10%, Mg: 0-0.10%, Co: 0-1.00%, As: 0-1.00%, Zr: 0-1.00%, Bismuth: 0-1.00%, Rare Earth Elements (REM): 0-0.3%, Balance Iron (Fe) and other unavoidable impurities.

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