Hot stamping part and method for manufacturing same

Abstract

The present disclosure provides a method of manufacturing a hot stamping component, the method including preparing a blank, heating the blank, transferring the heated blank to a press mold, forming and first piercing the transferred blank by hot-pressing the transferred blank into a shape of a hot stamping component and forming at least two holes in the transferred blank, and trimming the formed blank by cutting an outer portion of the formed blank using the at least two holes.

Description

Technical Field

[0001] The present disclosure relates to a hot stamping component and a method of manufacturing the same.Background Art

[0002] As environmental regulations and fuel efficiency regulations are strengthened worldwide, the need for lighter vehicle materials is increasing. Accordingly, research and development on ultra-high strength steel and hot stamping steel is actively being conducted.

[0003] Hot stamping is a process of manufacturing high-strength parts by rapidly cooling a steel plate while forming the steel plate in a press after heating the steel plate to a high temperature in a furnace. In addition, a piercing process may be additionally performed to cut / process holes in the high-strength parts.

[0004] The piercing process uses laser equipment or a press mold, but if laser equipment is used, the processing time may increase, and if a press mold is used, the cross-sectional quality may deteriorate.

[0005] Related technologies include Korean Patent Publication No. 10-2020-0080721 (Title of the invention: Hot stamping component manufacturing device and hot stamping component manufacturing method using the same).Disclosure of Invention Technical Problem

[0006] Embodiments of the present disclosure are characterized by forming a hole in a blank simultaneously with forming and cooling the blank, so that the quantity of blanks obtainable from a coil may be increased and the amount of scrap discarded may be reduced.Solution to Problem

[0007] An embodiment of the present disclosure provides a method of manufacturing a hot stamping component, the method including preparing a blank, heating the blank, transferring the heated blank to a press mold, forming and first piercing the transferred blank by hot-pressing the transferred blank into a shape of a hot stamping component and forming at least two holes in the transferred blank, and trimming the formed blank by cutting an outer portion of the formed blank using the at least two holes.

[0008] In the present embodiment, the preparing of the blank may include cutting a coil into the blank using a laser or a cold press mold.

[0009] In the present embodiment, the blank may include an outer portion of the coil.

[0010] In the present embodiment, in the heating of the blank, the blank may be heated to a temperature of Ac3 to 1000 °C.

[0011] In the present embodiment, the temperature of the blank before the forming and first piercing may be higher than an Ms temperature.

[0012] In the present embodiment, in the forming and first piercing, the transferred blank may be cooled within the press mold.

[0013] In the present embodiment, the transferred blank may be cooled for 3 seconds or more and 20 seconds or less In the present embodiment, the trimming may include cutting an outer portion of the formed blank using a laser or a cold press mold.

[0014] In the present embodiment, the method may further include second piercing the formed blank by forming an additional hole in the formed blank using the at least two holes.

[0015] In the present embodiment, the method may further include removing burrs formed on the blank after the trimming.

[0016] Another embodiment of the present disclosure provides a hot stamping component including a first shear surface by which a first hole is defined and a second shear surface formed on an edge of the hot stamping component, wherein a first flow line having a first length is formed in a portion adjacent to the first shear surface, and a second flow line or a first diagonal pattern having a second length that is less than the first length is formed in a portion adjacent to the second shear surface.

[0017] In the present embodiment, the first length may be 50 µm or more, and the second length may be less than 50 µm.

[0018] In the present embodiment, the hot stamping component may further include a third shear surface by which a second hole spaced apart from the first hole is defined.

[0019] In the present embodiment, the hot stamping component may further include a third flow line or a second diagonal pattern having a third length that is less than the first length in a portion adjacent to the third shear surface.

[0020] In the present embodiment, the hot stamping component may further include a fourth shear surface by which a third hole spaced apart from the first hole is defined.

[0021] In the present embodiment, the hot stamping component may further include a fourth flow line having a fourth length that is greater than the second length in a portion adjacent to the fourth shear surface.

[0022] In the present embodiment, an edge of the hot stamping component may have a curved shape.

[0023] In the present embodiment, the hot stamping component may include a plating layer, and the plating layer is provided along the edge of the hot stamping component.

[0024] Other aspects, features and advantages other than those described above will become apparent from the following detailed description, claims, and drawings for practicing the disclosure.Advantageous Effects of Invention

[0025] According to an embodiment of the present disclosure as described above, the productivity and quality of hot stamping components may be improved and, at the same time, the yield of raw material input may be improved.Brief Description of Drawings

[0026] FIG. 1 is a flowchart schematically illustrating a method of manufacturing a hot stamping component according to an embodiment of the present disclosure. FIG. 2 is a flowchart schematically illustrating a preparation operation of a method of manufacturing a hot stamping component according to an embodiment of the present disclosure. FIG. 3 is a plan view schematically illustrating a blank according to an embodiment of the present disclosure. FIG. 4 is a flowchart schematically illustrating a heating operation of a method of manufacturing a hot stamping component according to an embodiment of the present disclosure. FIG. 5 is a diagram illustrating a heating furnace having a plurality of sections in a heating operation of a method of manufacturing a hot stamping component according to an embodiment of the present disclosure. FIG. 6 and FIG. 7 are cross-sectional views schematically illustrating a forming and first piercing operation of a manufacturing process of a hot stamping component according to an embodiment of the present disclosure. FIG. 8 is a perspective view schematically illustrating a blank of a manufacturing process of a hot stamping component according to an embodiment of the present disclosure. FIG. 9 is a perspective view illustrating a second piercing operation of a manufacturing process of a hot stamping component according to an embodiment of the present disclosure. FIG. 10 is a perspective view schematically illustrating a hot stamping component according to an embodiment of the present disclosure. FIG. 11 is a cross-sectional view schematically illustrating a shear surface of a first hole of a hot stamping component according to an embodiment of the present disclosure. FIG. 12 is a cross-sectional view schematically illustrating a shear surface of a first additional hole or a shear surface of a first edge of a hot stamping component according to an embodiment of the present disclosure. FIG. 13 and FIG. 14 are a plan view and a cross-sectional view schematically illustrating a shear surface of a first additional hole or a shear surface of a first edge of a hot stamping component according to an embodiment of the present disclosure. FIG. 15 is a cross-sectional view schematically illustrating a shear surface of a second edge of a hot stamping component according to an embodiment of the present disclosure. FIGS. 16 and 17 are drawings illustrating differences according to the length of a flow line formed around a shear surface. FIGS. 18 and 19 are plan views showing the effect when applying a manufacturing method according to an embodiment of the present disclosure. Best Mode for Carrying out the Invention Mode for the Invention

[0027] The disclosure may be modified into various forms and may have various embodiments. In this regard, the disclosure will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. The advantages, features, and methods of achieving the advantages may be clear when referring to the embodiments described below together with the drawings. However, the disclosure may have different forms and should not be construed as being limited to the descriptions set forth herein.

[0028] The terms "first", "second", etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0029] In the following embodiments, the singular forms include the plural forms unless the context clearly indicates otherwise.

[0030] The terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features or constituent elements but do not preclude the presence or addition of one or more other features or constituent elements.

[0031] It will also be understood that when a film, a region, a constituent element is referred to as being "on" or "above" another element, the film, the region, or the constituent element may be in direct contact with the other element or other intervening film, region, or constituent element may be present.

[0032] In the drawings, thicknesses of layers and regions may be exaggerated or reduced for convenience of explanation. For example, the sizes and thicknesses of elements in the drawings are arbitrarily expressed for convenience of explanation, and thus, the current inventive concept is not limited to the drawings.

[0033] In the present disclosure, an expression such as "A and / or B" may include A, B, or A and B. Also, in the present disclosure, expressions such as "at least one of A and B" may include A, B or A and B.

[0034] In the following embodiments, when referring to "planar", this means when a target portion is viewed from above, and when referring to "cross-sectional", this means when a cross-section cut vertically from the target portion is viewed from a side. In the following embodiments, when referring to "overlapping", this includes "planar" and "cross-sectional" overlapping.

[0035] Hereafter, the disclosure will be described more fully with reference to the accompanying drawings. In describing the disclosure with reference to drawings, like reference numerals are used for elements that are substantially identical or correspond to each other.

[0036] FIG. 1 is a flowchart schematically illustrating a method of manufacturing a hot stamping component, according to an embodiment of the present disclosure.

[0037] Referring to FIG. 1, the method of manufacturing a hot stamping component according to an embodiment may include a preparation operation (S100), a heating operation (S200), a transferring operation (S300), a forming and first piercing operation (S400), and a trimming operation (S500). Specifically, the method of manufacturing a hot stamping component according to an embodiment may include the preparation operation (S100) of preparing a blank, the heating operation (S200) of heating the blank, the transfer operation (S300) of transferring the heated blank to a press mold, the forming and first piercing operation (S400) of hot-pressing the transferred blank to form a shape of a hot stamping component and forming at least two holes in the transferred blank, and the trimming operation (S500) of cutting an outer portion of the formed blank using the at least two holes.

[0038] FIG. 2 is a flowchart schematically illustrating a preparation operation of the method of manufacturing a hot stamping component according to an embodiment of the present disclosure, and FIG. 3 is a plan view schematically illustrating a blank 100 according to an embodiment of the present disclosure.

[0039] Referring to FIGS. 2 and 3, the preparation operation (S100) may be an operation of preparing the blank 100 for hot stamping. In an embodiment, the preparation operation (S100) may include a hot rolling operation (S110), a cooling / coiling operation (S120), a cold rolling operation (S130), an annealing operation (S140), a plating operation (S150), and a cutting operation (S160).

[0040] First, a reheating operation of a steel slab may be performed. In the reheating operation of a steel slab, a component segregated during casting may be re-dissolved by reheating he steel slab secured through a continuous casting process to a predetermined temperature. In an embodiment, the slab reheating temperature (SRT) may be in a range from about 1,200 °C to about 1,400 °C. If the SRT is lower than about 1,200 °C, the components segregated during casting are not sufficiently re-dissolved, making it difficult to significantly secure the homogenization effect of the alloy elements, and it may be difficult to significantly obtain the solid solution effect of titanium (Ti). The higher the SRT, the more advantageous it is for homogenization, but if the SRT exceeds about 1,400 °C, the austenite crystal grain size increases, making it difficult to secure strength, and the manufacturing cost of the steel plate may increase due to the excessive heating process.

[0041] In the hot rolling operation (S110), the reheated plate may be hot rolled at a predetermined finishing rolling temperature. A hot rolled steel sheet may be manufactured through the hot rolling operation (S110). In an embodiment, the finishing delivery temperature (FDT) may be in a range from about 880 °C to about 950 °C. At this time, if the FDT is lower than about 880 °C, it is difficult to secure the workability of the steel sheet due to the occurrence of a mixed grain structure caused by rolling on an abnormal region, and there is a problem that the workability is reduced due to non-uniformity of the microstructure, and a problem of sheetability during hot rolling may occur due to a rapid phase change. If the FDT exceeds about 950 °C, the austenite grains may become coarser, and the TiC precipitates may become coarser, which may deteriorate the performance of the hot stamping component.

[0042] In the cooling / coiling operation (S120), the hot rolled hot rolled steel sheet may be cooled to a predetermined coiling temperature (CT) and then coiled. In an embodiment, the coiling temperature of the cooling / coiling operation (S120) may be in a range from about 550 °C to about 800 °C. The CT affects the redistribution of carbon, and when the CT is less than about 550 °C, a low-temperature phase fraction due to overcooling may increase, which may increase the strength, and there is a concern that the rolling load may be severe during cold rolling, and the ductility may deteriorate rapidly. On the other hand, when the coiling temperature exceeds about 800 °C, abnormal crystal grain growth or excessive crystal grain growth may cause formability deterioration and strength deterioration.

[0043] In the cold rolling operation (S130), the coiled hot-rolled steel sheet may be uncoiled, pickled, and then cold-rolled. At this time, the pickling may be performed for the purpose of removing scale from the coiled hot-rolled steel sheet, i.e., the hot-rolled coil manufactured through the hot rolling process. A cold rolled steel sheet may be manufactured through the cold rolling operation (S130).

[0044] The annealing operation (S140) may anneal the cold rolled cold rolled steel sheet at a temperature of about 700 °C or higher. For example, the annealing operation (S140) may include an operation of heating the cold rolled steel sheet and cooling the heated cold rolled steel sheet at a predetermined cooling rate. The cold rolled steel sheet may be annealed in the annealing operation (S140). The annealing operation (S140) may be performed in an annealing furnace.

[0045] In an embodiment, the annealing temperature of the cold rolled steel sheet may be in a range from about 750 °C to about 900 °C. If the annealing temperature of the cold rolled steel sheet is less than about 750 °C, a desired structure may not be obtained, and recrystallization may not be sufficiently completed. On the other hand, if the annealing temperature of the cold rolled steel sheet exceeds approximately 900 °C, the annealing temperature may be too high, which may reduce the efficiency of the manufacturing process. Therefore, if the annealing temperature of the cold rolled steel sheet satisfies about 750 °C to about 900 °C, a desired structure may be obtained, recrystallization may be sufficiently completed, and the efficiency of the manufacturing process may be improved.

[0046] The plating operation (S150) may be an operation of forming a plating layer on the annealed cold rolled steel sheet. In an embodiment, a plating layer may be formed on the annealed cold rolled steel sheet through the plating operation (S150). At this time, the plating layer may include a zinc (Zn)-based plating layer or an aluminum (Al)-based plating layer.

[0047] Specifically, in the plating operation (S150), the annealed cold rolled steel sheet may be immersed in a plating bath. At this time, the plating bath may maintain a temperature of in a range from about 400 °C to about 700 °C. The amount of plating adhesion may be in a range from about 40 g / m 2< to about 200 g / m 2< on both sides of the base material of the cold rolled steel sheet. After the plating operation (S150), the cold rolled steel sheet with the plating layer formed may be wound into a coil shape.

[0048] In FIG. 2, the cold rolling operation (S130), the annealing operation (S140), and the plating operation (S150) are illustrated as being performed after the cooling / coiling operation (S120), but the present disclosure is not limited thereto. At least one of the cold rolling operation (S130), the annealing operation (S140), and the plating operation (S150) may be omitted. For example, the cold rolling operation (S130) and the annealing operation (S140) may be omitted. In this case, the hot rolled steel sheet on which the plating layer is formed after the plating operation (S150) may be coiled into a coil shape.

[0049] Thereafter, in the cutting operation (S160), the steel sheet (e.g., the cold rolled steel sheet or the hot rolled steel sheet) coiled into a coil shape is uncoiled, and then the steel sheet may be cut into the blank 100 using a laser or a cold press mold. At this time, the blank 100 may include the outer portion (or edge) of the coil. For example, the blank 100 may include an outer portion (or edge) of a steel plate.

[0050] Referring to FIG. 1, after the preparation operation (S100) of preparing the blank 100, a heating operation (S200) of heating the blank 100 may be performed. A heat source method in the heating operation (S200) may be direct heating or indirect heating. The heat source method in the heating operation (S200) may use one of direct heating and indirect heating or may use a combination of direct heating and indirect heating.

[0051] In an embodiment, the blank 100 may be heated in a heating furnace in the heating operation (S200). The heating furnace may be provided as one section equipped with one temperature range (or, single temperature), or may be provided as multiple sections having different temperature ranges. When the heating furnace is provided as one section equipped with one temperature range, the blank 100 may be heated to a target temperature in one temperature range within the heating furnace. At this time, the target temperature may be Ac3 to about 1,000 °C. That is, the blank 100 may be heated in a heating furnace having a temperature range of Ac3 to about 1,000 °C until the temperature of the blank 100 becomes Ac3 to about 1,000 °C.

[0052] On the other hand, if the heating furnace is equipped with multiple sections having different temperature ranges, the blank 100 may be heated to a target temperature in different temperature ranges within the heating furnace.

[0053] FIG. 4 is a flowchart schematically illustrating a heating operation of a method of manufacturing a hot stamping component according to an embodiment of the present disclosure, and FIG. 5 is a diagram illustrating a heating furnace having multiple sections in the heating operation of a method of manufacturing a hot stamping component according to an embodiment of the present disclosure.

[0054] Referring to FIGS. 4 and 5, in the heating operation (S200), the blank 100 (see FIG. 3) may be heated in a heating furnace having multiple sections having different temperature ranges. As shown in FIG. 4, the heating operation (S200) may include a step heating operation (S210) and a soaking operation (S220). The step heating operation (S210) and the soaking operation (S220) may be operations in which the blank 100 is heated while passing through a plurality of sections provided in the heating furnace.

[0055] In an embodiment, the overall temperature of the heating furnace may be in a range from about 680 °C to about 1,000 °C. Specifically, the overall temperature of the heating furnace in which the step heating operation (S210) and the soaking operation (S220) are performed may be in a range from about 680 °C to about 1,000 °C. At this time, the temperature of the heating furnace in which the step heating operation (S210) is performed may be in a range from about 680 °C to about Ac3, and the temperature of the heating furnace in which the soaking operation (S220) is performed may be in a range from about Ac3 to about 1,000 °C.

[0056] In the step heating operation (S210), the blank 100 may be heated (or increased temperature) stepwise while passing through multiple sections provided in the heating furnace. Among the multiple sections provided in the heating furnace, there may be multiple sections in which the step heating operation (S210) is performed, and the temperature is set for each section so that the temperature increases from an inlet of the heating furnace into which the blank 100 is introduced toward an outlet of the heating furnace from which the blank 100 is taken out, and thus, the blank 100 may be heated (or increased temperature) in stages.

[0057] The soaking operation (S220) may be performed after the step heating operation (S210). In the soaking operation (S220), the step heated blank 100 may be heated (or increased temperature) while passing through a section of the heating furnace set to a temperature in a range of about Ac3 to about 1,000 °C. Among the multiple sections provided in the heating furnace, there may be at least one section in which the soaking operation (S220) is performed.

[0058] According to an embodiment, the heating furnace may have multiple sections having different temperature ranges. Specifically, the heating unit may have a first section P 1 having a first temperature range T 1 , a second section P 2 having a second temperature range T 2 , a third section P 3 having a third temperature range T 3 , a fourth section P 4 having a fourth temperature range T 4 , a fifth section P 5 having a fifth temperature range T 5 , a sixth section P 6 having a sixth temperature range T 6 , and a seventh section P 7 having a seventh temperature range T 7 .

[0059] In an embodiment, in the step heating operation (S210), the blank may be heated stepwise while passing through the first section P 1 to the fourth section P 4 defined in the heating unit. In addition, in the soaking operation (S220), the blank that has been step heated in the first section P 1 to the fourth section P 4 may be soaked while passing through the fifth section P 5 to the seventh section P 7 .

[0060] Sections 1 P 1 to 7 P 7 may be arranged sequentially within the heating furnace. The first section P 1 having the first temperature range T 1 may be adjacent to the inlet of the eating furnace into which the blank 100 is introduced, and the seventh section P 7 having the seventh temperature range T 7 may be adjacent to the outlet of the heating furnace from which the blank 100 is taken out. Therefore, the first section P 1 having the first temperature range T 1 may be the first section of the heating furnace, and the seventh section P 7 having the seventh temperature range T 7 may be the last section of the heating furnace.

[0061] The temperatures of the plurality of sections provided in the heating furnace, for example, the temperatures of the first section P 1 to the seventh section P 7 , may increase from the inlet of the heating furnace into which the blank is introduced to the outlet of the heating furnace from which the blank is taken out. However, the temperatures of the fifth section P 5 , the sixth section P 6 , and the seventh section P 7 may be the same. Additionally, a temperature difference between two adjacent sections among the multiple sections provided in the heating furnace may be greater than 0 °C and less than 100 °C. For example, the temperature difference between the first section P 1 and the second section P 2 may be greater than 0 °C and less than 100 °C.

[0062] The temperature of the heating furnace during the soaking operation (S220) may be in a range from about Ac3 to about 1,000 °C. If the temperature of the heating furnace during the soaking operation (S220) is less than Ac3, the manufactured hot stamping component may not have a desired material. On the other hand, if the temperature of the heating furnace during the soaking operation (S220) exceeds about 1,000 °C, carbide-forming elements or nitride-forming elements such as Ti, V, Nb, and Mo in the blank 100 may be dissolved into the parent material, making it difficult to suppress grain coarsening.

[0063] Although FIG. 5 illustrates a heating furnace according to an embodiment having seven sections having different temperature ranges, the present disclosure is not limited thereto. The furnace may have five, six, or eight zones with different temperature ranges.

[0064] In an embodiment, the heating operation (S200) is provided with a step heating operation (S210) and a soaking operation (S220), so that the temperature of the heating furnace may be set stepwise, thereby improving the energy efficiency of the heating furnace.

[0065] In an embodiment, the heating furnace may have a length of about 20 m to about 40 m along a transport path of the blank 100. The heating furnace may have a plurality of sections having different temperature ranges, and a ratio of the length of the section in which the blank 100 is step heated among the plurality of sections and the length of the section in which the blank 100 is soaked among the plurality of sections may satisfy about 1:1 to about 4:1. If the length of the section in which the blank 100 is soaked within the heating furnace increases and, as a result, the ratio of the length of the section in which the blank 100 is step heated and the length of the section in which the blank 100 is soaked exceeds about 1:1, the amount of hydrogen penetrating into the blank 100 in the soaking section may increase, thereby increasing delayed fracture. On the other hand, if the length of the section in which the blank 100 is soaked is reduced and, as a result, the ratio of the length of the section in which the blank 100 is step heated and the length of the section in which the blank is soaked is less than about 4:1, the crack-heating section (or time) is not sufficiently secured, thus, the strength of the manufactured hot stamping component may be uneven. For example, the length of the uniform heating section among the multiple sections provided in the heating furnace may be in a range from about 20% to about 50% of the total length of the heating furnace.

[0066] In an embodiment, the total heating time for which the heating operation (S200) is performed may be in a range from about 2 min to about 20 min. That is, the total time for which the blank 100 remains in the heating furnace may be in a range from about 2 min to about 20 min. If the total heating time for which the heating operation (S200) is performed is about 2 min or less, the manufactured hot stamping component may not have a desired material due to insufficient heating time. On the other hand, if the total heating time during which the heating operation (S200) is performed is approximately 20 minutes or longer, the heating time may be too long, which may lower the production speed and reduce economic feasibility. Therefore, when the total heating time during which the heating operation (S200) is performed satisfies about 2 min to about 20 min, the manufactured hot stamping component may have a desired material, and at the same time, the deterioration of the economic efficiency of the manufacturing process may be prevented or minimized.

[0067] Referring to FIG. 1, the transfer operation (S300) may be performed after the heating operation (S200). In the transfer operation (S300), the heated blank 100 may be transferred to a press mold 400 (see FIG. 6). For example, the heated blank 100 may be taken out from the heating furnace and then transferred to the press mold 400.

[0068] In the transfer operation (S300), the heated blank 100 may be cooled at an ambient temperature (or, room temperature). That is, the heated blank 100 may be air-cooled at an ambient temperature during transfer. If the heated blank 100 is not air-cooled, the mold entry temperature (e.g., molding start temperature) may increase, which may cause wrinkles (or bends) to occur on a surface of the manufactured hot stamping component. In addition, because the use of a refrigerant may affect the subsequent process (hot stamping), it may be desirable for the heated blank 100 to be air-cooled during transport.

[0069] FIGS. 6 and 7 are cross-sectional views illustrating the forming and first piercing operation of a manufacturing process of a hot stamping component according to an embodiment of the present disclosure, and FIG. 8 is a perspective view schematically illustrating a blank of a manufacturing process of a hot stamping component according to an embodiment of the present disclosure. Specifically, FIG. 6 is a cross-sectional view of a blank and a press mold before the forming and first piercing operation are performed, FIG. 7 is a cross-sectional view of a blank and a press mold while the forming and first piercing operation is performed, and FIG. 8 is a perspective view schematically illustrating a blank after the forming and first piercing operation.

[0070] Referring to FIGS. 1, 6, 7, and 8, the forming and first piercing operation (S400) may be performed after the transfer operation (S300). The forming and first piercing operation (S400) may be an operation of hot-pressing the transferred blank 100 to form the blank 100 into the shape of a hot stamping component and forming at least two holes 110 in the transferred blank 100.

[0071] In an embodiment, the forming and first piercing operation (S400) may be performed in the press mold 400. The press mold 400 may include a lower mold 410, an upper mold 420, and a punch 430. The lower mold 410 may have a bottom surface shape of a hot stamping component. The upper mold 420 may face the lower mold 410 and have a top surface shape of the hot stamping component. The press mold 400 may have at least one punch 430, preferably at least two punches 430. In an embodiment, the punch 430 may include a first punch and a second punch.

[0072] For example, as described later, because a laser process or a cold piercing process must be performed using the holes formed through hot piercing, at least two or more holes may be formed through hot piercing. Specifically, subsequent processes should be performed after seating the blank 100 on a tool by using the holes formed through hot piercing as guide patterns (or reference points), the holes formed in the blank 100 through hot piercing may be at least two or more.

[0073] However, the present disclosure is not limited thereto. For example, various modifications are possible, such as only one punch 430 or three or more punches 430 may be provided on the press mold 400.

[0074] Although not shown, when the press mold 400 is equipped with only one punch 430, one foam bead may be formed at an edge of the blank 100 when the blank 100 is formed.

[0075] In an embodiment, the clearance between the punch 430 and the mold (e.g., the lower mold 410 and / or the upper mold 420) may be in a range from about 2% to about 30%. If the clearance is less than about 2%, the punch 430 may become stuck in the press mold 400 due to thermal expansion of the press mold 400. On the other hand, if the clearance is more than about 30%, the vibration of the punch 430 may become severe, which may result in uneven quality, including flow lines of the shear surface. For example, the uniformity of the flow lines may deteriorate, such as the flow lines being formed in large numbers only in a portion of the shear surface. Accordingly, when the clearance between the punch 430 and the press mold 400 (e.g., the lower mold 410 and / or the upper mold 420) is about 2% to about 30%, the punch 430 may be prevented from being stuck in the press mold 400 due to thermal expansion, and the flow lines may be uniformly formed around the shear surface.

[0076] In an embodiment, the blank 100 may be hot-pressed in the forming and first piercing operation (S400). Specifically, the blank 100 may be hot-pressed to be formed into the shape of a hot stamping component by using the press mold 400 including the lower mold 410 and the upper mold 420. Specifically, the upper mold 420 having the shape of the upper surface of the hot stamping component may be pressurized (e.g., hot-pressed) with the lower mold 410 having the shape of the lower surface of the hot stamping component and the blank 100, thereby forming the blank 100 into the shape of a hot stamping component.

[0077] In an embodiment, in the forming and first piercing operation (S400), the blank 100 may be hot-pressed and hot-pierced at the same time. Specifically, when hot forming the blank 100, the punch 430 included in the press mold 400 may be lowered to perform hot piercing on the blank 100. Alternatively, in the forming and first piercing operation (S400), the punch 430 included in the press mold 400 may be lowered after the hot forming of the blank 100 is completed, and thus, a hot piercing may be performed in the blank 100. That is, in the forming and first piercing operation (S400), the punch 430 included in the press mold 400 may be lowered simultaneously with the hot forming of the blank 100 or after the hot forming of the blank 100 is completed, so that hot piercing may be performed in the blank 100.

[0078] In an embodiment, when hot forming the blank 100 using the press mold 400, a first punch and the second punch included in the press mold 400 may be lowered, and thus, at least two holes, that is, first and second holes 110a and 110b may be formed in the blank 100. Specifically, in the process of hot forming the blank 100 by pressurizing the lower mold 410 and the blank 100 with the upper mold 420, the first punch and the second punch may be lowered to form the first hole 110a and the second hole 110b in the blank 100. Hot piercing may be performed simultaneously with the hot forming. Alternatively, the hot piercing may be performed after the hot forming is completed. That is, the hot piercing may be performed simultaneously with the hot forming or after the hot forming is completed.

[0079] In FIGS. 6 and 7, the punch 430 included in the press mold 400 is shown as being lowered to form a hole 110 in the blank 100, but the present disclosure is not limited thereto. Although not shown, the hole 110 may be formed in the blank 100 through a separately provided external device.

[0080] In an embodiment, the temperature of the blank 100 before the forming and first piercing operation (S400) is performed may be equal to or greater than the martensite start (Ms) temperature. If the temperature of the blank 100 before the forming and first piercing operation (S400) is performed is lower than the Ms temperature, a large load may occur during the forming and first piercing, which may cause damage to the press mold 400 and / or the punch 430. Preferably, the hot piercing may be performed at a temperature of about 350 °C or more and about 750 °C or less. More preferably, the hot piercing may be performed at a temperature of about 400 °C or more and about 700 °C or less.

[0081] In an embodiment, the blank 100 may be cooled while being formed into a final component shape in the press mold 400 (or during hot forming). The press mold 400 may be provided with cooling channels 440 through which a coolant circulates inside. For example, the cooling channels 440 may be provided inside the lower mold 410 and the upper mold 420, respectively. Specifically, the cooling channels 440 may be arranged inside the lower mold 410 and the upper mold 420 along surfaces of the lower mold 410 and the surface of the upper mold 420. The blank 100 heated by circulation of a coolant supplied through the cooling channel 440 provided in the press mold 400 may be rapidly cooled. At this time, in order to prevent the spring back phenomenon of a plate material and also to maintain the desired shape, rapid cooling may be performed while pressurizing the press mold 400 in a closed state. In performing the forming and cooling operation of the heated blank 100, the heated blank 100 may be cooled to the martensite finish temperature with an average cooling rate of at least about 10 °C / s or more. Preferably, the cooling may be performed at a minimum of about 20 °C / s or more.

[0082] The blank 100 may be maintained in the press mold 400 for about 3 seconds to about 20 seconds. For example, a holding state of the press mold 400 may be maintained for about 3 seconds to about 20 seconds. If the holding time in the press mold 400 is less than about 3 seconds, sufficient cooling of the blank 100 may not occur, which may cause thermal deformation due to residual heat and temperature differences between components, which may result in a deterioration in dimensional quality. On the other hand, if the holding time in the press mold 400 exceeds about 20 seconds, the holding time in the press mold 400 may become longer, which may lower productivity.

[0083] In an embodiment, the processes of hot press forming the heated blank 100, hot piercing the heated blank 100, and cooling the heated blank 100 may be performed simultaneously in the press mold 400. For example, the hot pressing, hot piercing, and cooling of the blank 100 may be performed simultaneously in a closed (or engaged) state of the press mold 400.

[0084] FIG. 9 is a perspective view illustrating a trimming operation of a manufacturing process of a hot stamping component according to an embodiment of the present disclosure.

[0085] Referring to FIG. 1 and FIG. 9, the trimming operation (S500) may be performed after the forming and first piercing operation (S400). The trimming operation (S500) may be an operation of cutting an outer portion of the molded blank 100 using at least two holes, that is, the first and second holes 110a and 110b formed in the molded blank 100. In other words, the trimming operation (S500) may be an operation of cutting an outer portion of the blank 100 using the at least two holes 110a and 110b formed in the blank 100 through hot piercing.

[0086] In an embodiment, the trimming operation (S500) may be an operation of cutting the edge of the blank 100 using the at least two holes 110a and 110b formed through hot piercing as reference points (or, guide patterns). In other words, the blank 100 may be seated in a tool using the at least two holes 110a and 110b formed in the molded blank 100 and the edge of the molded blank 100 may be cut. For example, after inserting fixing pins 510a and 510b into the at least two holes 110a and 110b formed in the molded blank 100, an outer portion of the molded blank 100 may be cut.

[0087] In an embodiment, the trimming operation (S500) may be performed using a laser or a press mold (e.g., a cold press mold).

[0088] According to an embodiment of the present disclosure, in the method of manufacturing a hot stamping component, after forming the hole 110 in the blank 100 through hot piercing, then additionally cut an outer portion of the blank 100 through cold trimming or laser trimming. That is, according to an embodiment of the present disclosure, in the method of manufacturing a hot stamping component, a hot piercing process may be performed on the blank 100, the blank 100 is cooled, and then cold trimming or laser trimming is performed on the blank 100.

[0089] In an embodiment, a second piercing operation may be performed after the forming and first piercing operation (S400). The second piercing operation may be an operation of forming an additional hole 120 in the formed blank 100 using the at least two holes 110a and 110b formed in the formed blank 100. In other words, the second piercing operation may be an operation of forming an additional hole (e.g., an additional hole 120) in the blank 100 by using the two holes 110a and 110b formed in the blank 100 through hot piercing.

[0090] In an embodiment, the second piercing operation may be performed during the trimming operation (S500). For example, the second piercing operation and the trimming operation (S500) may be performed simultaneously. Alternatively, the second piercing operation may be performed before the trimming operation (S500) or after the trimming operation (S500). For example, the second piercing operation and the trimming operation (S500) may be performed sequentially.

[0091] Although FIG. 9 illustrates that two additional holes 120a and 120b are formed through the second piercing operation, the present disclosure is not limited thereto. The one additional hole 120 may be formed, or three or more additional holes 120 may be formed.

[0092] In an embodiment, in the second piercing operation, the at least two holes 110a and 110b formed through hot piercing may be used as reference points (or guide patterns) to form the additional holes 120a and 120b in the blank (100). In other words, the blank 100 may be seated to a tool using the at least two holes 110a and 110b formed in the molded blank 100, and the additional holes 120a and 120b may be formed in the molded blank 100. For example, after inserting the fixing pins 510a and 510b into each of the at least two holes 110a and 110b formed in the molded blank 100, then the additional holes 120a and 120b may be formed in the molded blank 100.

[0093] In an embodiment, the additional holes 120a and 120b in the second piercing operation may be formed using a laser or a cold press mold. In FIG. 9, the two additional holes 120a and 120b are shown to be formed through the second piercing operation, but the present disclosure is not limited thereto. The one additional hole 120 may be formed, or three or more additional holes 120 may be formed.

[0094] In the method of manufacturing a hot stamping component according to an embodiment of the present disclosure, after forming the hole 110 in the blank 100 through hot piercing, a hole (e.g., the additional hole 120) may be additionally formed in the blank 100 through cold piercing or laser piercing. That is, according to an embodiment of the present disclosure, in the method of manufacturing a hot stamping component, a hot piercing process may be performed on the blank 100, the blank 100 on which the hot piercing process has been performed is cooled, and then a cold piercing process or a laser piercing process may be performed.

[0095] In an embodiment, a portion of the outer edge of the manufactured hot stamping component may be an edge of a coil raw material. That is, a portion of the outer edge of the manufactured hot stamping component may be the edge of the coil raw material without being cut.

[0096] In an embodiment, after the trimming operation (S500) and / or the second piercing operation are performed, an operation of removing burrs formed in the blank 100 may be performed. Through this process, the burrs formed in processes such as hot piercing, cold piercing, and cold trimming may be removed.

[0097] FIG. 10 is a perspective view schematically illustrating a hot stamping component according to an embodiment of the present disclosure.

[0098] Referring to FIG. 10, a hot stamping component 1000 according to an embodiment may include a hole 110 and an additional hole 120. The hot stamping component 1000 may include an edge 130. In addition, the hot stamping component 1000 may include shear surfaces 150a, 150b, 150c, 150d, 150e, and 150f defined in the hole 110, the additional hole 120, and the edge 130, respectively.

[0099] As described above in the manufacturing method of the hot stamping component 1000, the hot stamping component 1000 may include at least two holes 110. The holes 110 may include a first hole 110a and a second hole 110b. That is, the hot stamping component 1000 may include the first hole 110a and the second hole 110b. In FIG. 10, the hot stamping component 1000 is illustrated as having two holes 110a and 110b, but the present disclosure is not limited thereto. For example, the hot stamping component 1000 may be provided with one or three or more holes.

[0100] In addition, the hot stamping component 1000 may include at least one additional hole 120. For example, the hot stamping component 1000 may include a first additional hole 120a and a second additional hole 120b. Although FIG. 10 illustrates that two additional holes, that is, the first and second additional holes 120a and 120b are provided, but the present disclosure is not limited thereto. The number of additional holes 120 provided in the hot stamping component 1000 may be one or three or more.

[0101] At this time, the first hole 110a and the second hole 110b may be formed through the forming and first piercing operation (S400), and the first additional hole 120a and the second additional hole 120b may be formed through the second piercing operation. For example, the first hole 110a and the second hole 110b may be formed through hot piercing, and the first additional hole 120a and the second additional hole 120b may be formed through cold piercing or laser piercing.

[0102] In addition, the hot stamping component 1000 may include the edge 130. In this case, the edge 130 of the hot stamping component 1000 may denote a surface extending along a long side of the hot stamping component 1000. The edge 130 may include a first edge 130a and a second edge 130b. That is, the hot stamping component 1000 may include the first edge 130a and the second edge 130b.

[0103] In an embodiment, a shear surface 150 may include a first shear surface 150a, a second shear surface 150b, a third shear surface 150c, a fourth shear surface 150d, a fifth shear surface 150e, and a sixth shear surface 150f. The first shear surface 150a, the second shear surface 150b, the third shear surface 150c, the fourth shear surface 150d, the fifth shear surface 150e, and the sixth shear surface 150f may be formed together during a process in which the first hole 110a, the second hole 110b, the first additional hole 120a, the second additional hole 120b, the first edge 130a, and the second edge 130b are formed, respectively. That is, the first shear surface 150a, the second shear surface 150b, the third shear surface 150c, the fourth shear surface 150d, the fifth shear surface 150e, and the sixth shear surface 150f may be formed together when the first hole 110a, the second hole 110b, the first additional hole 120a, the second additional hole 120b, the first edge 130a, and the second edge 130b are formed, respectively.

[0104] In other words, the first hole 110a may be defined by the first shear surface 150a, the second hole 110b may be defined by the second shear surface 150b, the first additional hole 120a may be defined by the third shear surface 150c, the second additional hole 120b may be defined by the fourth shear surface 150d, the first edge 130a may be defined by the fifth shear surface 150e, and the second edge 130b may be defined by the sixth shear surface 150f.

[0105] FIG. 11 is a cross-sectional view schematically illustrating a shear surface of a first hole of a hot stamping component according to an embodiment of the present disclosure, FIG. 12 is a cross-sectional view schematically illustrating a shear surface of a first additional hole or a shear surface of a first edge of a hot stamping component according to an embodiment of the present disclosure, FIGS. 13 and 14 are a plan view and a cross-sectional view schematically illustrating a shear surface of a first additional hole or a shear surface of a first edge of a hot stamping component according to an embodiment of the present disclosure, and FIG. 15 is a cross-sectional view schematically illustrating a shear surface of a second edge of a hot stamping component according to an embodiment of the present disclosure.

[0106] For example, FIG. 11 is a cross-sectional view schematically illustrating a shear surface in which hot piercing is performed, FIG. 12 is a cross-sectional view schematically illustrating a shear surface in which cold piercing (or, cold press mold) is performed, FIGS. 13 and 14 are a plan view and a cross-sectional view schematically illustrating a front surface and a cross-section of a shear surface in which laser piercing or laser trimming is performed, and FIG. 15 is a cross-sectional view schematically illustrating a shear surface when the shear surface is an edge of a coil raw material. FIGS. 11, 12, and 15 correspond to cross-sections observed with an optical microscope after etching a cross-section, and FIGS. 13 and 14 correspond to cross-sections observed with an optical microscope in which the front surface of the shear surface is not etched and the cross-section of the shear surface is observed with an optical microscope. In FIGS. 11 to 15, the shapes and characteristics of the shear surfaces are illustrated as examples for convenience of explanation.

[0107] Referring to FIGS. 10 and 11, the hot stamping component 1000 may include the first shear surface 150a by which the first hole 110a is defined, and when observed with an optical microscope after etching a cross-section of the first shear surface 150a, first flow lines 1100 having a first length may be formed in a portion adjacent to the first shear surface 150a. At this time, the first length may be about 50 µm or more. In addition, a first burr 1110 may be formed around the first shear surface 150a. At this time, the first length may be defined as an average length of the first flow lines 1100 formed in a portion adjacent to the first shear surface 150a.

[0108] That is, if the first hole 110a included in the hot stamping component 1000 is formed through hot piercing, the flow line (e.g., the first flow line 1100) having a length of about 50 µm or more may exist in a portion adjacent to the first shear surface 150a by which the first hole 110a is defined. Therefore, if the flow line (e.g., the first flow line 1100) having a length of about 50 µm or more exists in a portion adjacent to the first shear surface 150a by which the first hole 110a is defined, it may be understood that the first hole 110a is formed through hot piercing. In other words, if the flow lines (e.g., the first flow lines 1100) formed in a portion adjacent to the first shear surface 150a by which the first hole 110a is defined have an average length of about 50 µm or more, the first hole 110a may be formed through hot piercing.

[0109] Referring to FIGS. 10 and 12, the hot stamping component 1000 may include the third shear surface 150c by which the first additional hole 120a is defined, and when observed with an optical microscope after etching a cross-section, second flow lines 1200 having a second length smaller than a first length may be formed in a portion adjacent to the third shear surface 150c. At this time, the second length may be less than about 50µm. In addition, a second burr 1210 may be formed around the third shear surface 150c. However, a height of the second burr 1210 formed around the third shear surface 150c may be less than a height of the first burr 1110 formed around the first shear surface 150a. In addition, the second length may be defined as an average length of the second flow lines 1200 formed in a region adjacent to the third shear surface 150c.

[0110] That is, if the first additional hole 120a included in the hot stamping component 1000 is formed through cold piercing (or cold press mold), the flow line (e.g., the second flow line 1200) having a length of less than about 50 µm may exist in a portion adjacent to the third shear surface 150c by which the first additional hole 120a is defined. Accordingly, if the flow line (e.g., the second flow line 1200) having a length of less than about 50 µm exists in a portion adjacent to the third shear surface 150c by which the first additional hole 120a is defined, it may be understood that the first additional hole 120a is formed through cold piercing (or, cold press mold). In other words, if the flow lines (e.g., the second flow lines 1200) formed in a portion adjacent to the third shear surface 150c by which the first additional hole 120a is defined have an average length of less than about 50 µm, the first additional hole 120a may be formed through cold piercing (or, cold press mold).

[0111] Also, the hot stamping component 1000 may include the fifth shear surface 150e by which the first edge 130a is defined, and when observed with an optical microscope after etching a cross-section, the second flow lines 1200 having a second length less than the first length may be formed in a portion adjacent to the fifth shear surface 150e. At this time, the second length may be less than about 50 µm. In addition, the second burr 1210 may be formed around the fifth shear surface 150e. However, the height of the second burr 1210 formed around the fifth shear surface 150e may be less than the height of the first burr 1110 formed around the first shear surface 150a. In addition, the second length may be defined as an average length of the second flow lines 1200 formed in a portion adjacent to the first edge 130a.

[0112] That is, if the first edge 130a included in the hot stamping component 1000 is formed through cold trimming (or cold press mold), a flow line (e.g., the second flow line 1200) having a length of less than about 50 µm may exist in a portion adjacent to the fifth shear surface 150e by which the first edge 130a is defined. Accordingly, if a flow line (e.g., the second flow line 1200) having a length of less than about 50 µm exists in a portion adjacent to the fifth shear surface 150e by which the first edge 130a is defined, it may be understood that the first edge 130a is formed through cold trimming (or, cold press mold). In other words, if the flow lines (e.g., the second flow lines 1200) formed in a portion adjacent to the fifth shear surface 150e by which the first edge 130a is defined have an average length of less than about 50 µm, the first edge 130a may be formed through cold trimming (or, cold press mold).

[0113] Referring to FIGS. 10, 13 and 14, the hot stamping component 1000 may include the third shear surface 150c by which the first additional hole 120a is defined, and a flow line may not be formed in a portion adjacent to the third shear surface 150c. However, a diagonal pattern 1300 may be provided on the third shear surface 150c along a shear surface. In addition, a microstructure different from the parent material may exist along the third shear surface 150c with a thickness (or width) of about 20 µm or less in a direction perpendicular to the third shear surface 150c. In addition, a draw 1310 may exist on a lower side of the hot stamping component 1000.

[0114] That is, if the first additional hole 120a included in the hot stamping component 1000 is formed through laser piercing, the diagonal pattern 1300 rather than a single line may exist in a portion adjacent to the third shear surface 150c by which the first additional hole 120a is defined. Accordingly, when a diagonal pattern 1300 exists in a portion adjacent to the third shear surface 150c by which the first additional hole 120a is defined, it may be understood that the first additional hole 120a was formed through laser piercing. In other words, if a diagonal pattern, not a single-line pattern, exists in a portion adjacent to the third shear surface 150c by which the first additional hole 120a is defined, the first additional hole 120a may be formed through laser piercing.

[0115] In addition, the hot stamping component 1000 may include the fifth shear surface 150e by which the first edge 130a is defined, and a single-line pattern may not be formed in a portion adjacent to the fifth shear surface 150e. However, the fifth shear surface 150e may be provided with the diagonal pattern 1300 along the shear surface. In addition, a microstructure different from the base material may have a thickness (or width) of about 20 µm or less along the shear surface in a direction perpendicular to the shear surface. In addition, the draw 1310 may exist on a lower side of the hot stamping component 1000.

[0116] That is, if the first edge 130a included in the hot stamping component 1000 is formed through laser trimming, the diagonal pattern 1300 rather than a single line may exist in a portion adjacent to the fifth shear surface 150e where the first edge 130a is defined. Therefore, if the diagonal pattern 1300 exists in a portion adjacent to the fifth shear surface 150e by which the first edge 130a is defined, it may be understood that the first edge 130a is formed through laser trimming. In other words, if a diagonal pattern, not a line pattern, exists in a portion adjacent to the fifth shear surface 150e by which the first edge 130a is defined, the first edge 130a may be formed through laser trimming.

[0117] The first additional hole 120a of the hot stamping component 1000 may be formed by a cold piercing (or cold press mold) or laser piercing process. In addition, the first edge 130a of the hot stamping component 1000 may be formed by a cold trimming (or cold press mold) or laser trimming process.

[0118] Referring again to FIGS. 10 and 11, the hot stamping component 1000 may include the second shear surface 150b by which the second hole 110b is defined, and first flow lines 1100 having a third length that is greater than the second length may be formed in a portion adjacent to the second shear surface 150b. At this time, the third length may be about 50 µm or more. In addition, the first burr 1110 may be formed around the second shear surface 150b. At this time, the third length may be defined as an average length of the first flow lines 1100 formed in a portion adjacent to the second shear surface 150b.

[0119] In an embodiment, the second additional hole 120b may be provided identically or similarly to the first additional hole 120a or the first edge 130a. Additionally, the second edge 130b may be provided identically or similarly to the first additional hole 120a or the first edge 130a. However, the present disclosure is not limited thereto.

[0120] In an embodiment, the first edge 130a and / or the second edge 130b of the hot stamping component 1000 may be an edge of the coil raw material. For example, when the first edge 130a and / or the second edge 130b of the hot stamping component 1000 are observed with an optical microscope after etching the cross-section, no part damaged by a flow line or external force is found, and the first edge 130a and / or the second edge 130b of the hot stamping component 1000 may form a curved line shape (e.g., a curved shape). In this case, a plating layer 1420 may be formed along the cross-sectional edge.

[0121] In an embodiment, the hot stamping component 1000 may include the hole 110, the additional hole 120, and the edge 130, and when observed under an optical microscope after etching the cross-section, flow lines (e.g., the first flow lines 1100) having a length of about 50 µm or longer may exist on a portion adjacent to the shear surface (e.g., a first shear surface 150a and a second shear surface 150b) by which the hole 110 is defined, and the first burr 1110 may be formed. At this time, the length of the flow lines may be an average length of the flow lines. flow lines (e.g., the second flow lines 1200) having a length of less than about 50 µm may exist in the portion adjacent to a shear surface (e.g., the third shear surface 150c, the fourth shear surface 150d, the fifth shear surface 150e, and the sixth shear surface 150f) by which the additional hole 120 and / or the edge 130 are defined, and the second burr 1210 may be formed. At this time, the length of the flow lines may be an average length of the flow lines.

[0122] Alternatively, in a portion adjacent to a shear surface (e.g., the third shear surface 150c, the fourth shear surface 150d, the fifth shear surface 150e, and the sixth shear surface 150f) by which the additional holes 120 and / or edges 130 are defined, no flow lines may be provided but the diagonal pattern 1300 may be provided along the shear surface, and a microstructure different from the parent material may exist along the shear surface with a thickness (or width) of about 20 µm or less in a direction perpendicular to the shear surface, and the draw 1310 may be formed adjacent to the shear surface.

[0123] After the heated blank 100 is formed and cooled, a piercing process for cutting a hole in the cooled blank 100 and a trimming process for cutting an unnecessary outer portion may be performed. At this time, the piercing process uses a laser or a press mold (e.g., a cold press mold). If the piercing process is performed using a laser, there is no processing load and the quality of a shear surface is good, but the processing time is long, and accordingly, the processing cost may increase. On the other hand, if the piercing process is performed using a press mold, the processing time is fast and the processing cost is low, but the processing load is large and the quality of the shear surface may be inferior.

[0124] In an embodiment, hot piercing may be performed simultaneously in the process of forming and cooling the heated blank 100. That is, the processes of hot press forming the heated blank 100, hot piercing the heated blank 100, and cooling the heated blank 100 may be performed simultaneously (or together) in the press mold 400. Therefore, the number of holes to be formed in the cooled blank 100 may be reduced by forming the holes in the blank 100 in advance at a high temperature. That is, by forming holes in the blank 100 in advance at a high temperature, the process of forming holes in the cooled blank 100 may be simplified, thereby reducing the processing time and reducing the processing cost, and thus, the hot stamping component 1000 with a small processing load and a good quality of a shear surface may be provided.

[0125] In addition, in performing the piercing process and the trimming process, after forming arbitrary shapes in an outer region of the blank 100 that is not included in the final product during the hot press, and then the blank 100 may be secured in a tool using the arbitrary shapes, and the piercing process and the trimming process may be performed. However, this may cause the size of the blank 100 used in the method of manufacturing a hot stamping component to become larger than necessary compared to the final product, which may reduce the material yield, increase the amount of scrap, and may cause economic and environmental problems.

[0126] In an embodiment, during the process of hot forming the blank 100, at least two holes 110a and 110b may be formed in the blank 100 through hot piercing simultaneously (or together), and by performing a cold piercing process and a cold trimming process using the at least two holes 110a and 110b formed as guide patterns (or reference points), the size of the blank 100 used in the method of manufacturing a hot stamping component may be prevented from becoming unnecessarily large compared to the final product, thus, the material yield may be increased, the amount of waste scrap may be reduced, and as a result, the economy may be improved and the environment may be protected.

[0127] In an embodiment, the flow lines (e.g., the first flow line 1100) having a length of about 50 µm or more may be present adjacent to a first shear surface 150a by which the first hole 110a is defined, and the flow lines (e.g., the second flow lines 1200) having a length of less than about 50 µm may be present adjacent to the third shear surface 150c by which the first additional hole 120a is defined. That is, a length of the flow line formed in a portion adjacent to the first shear surface 150a by which the first hole 110a is defined may be greater than a length of the flow line formed in a portion adjacent to the third shear surface 150c by which the first additional hole 120a is defined. At this time, the length may be an average length of the flow line.

[0128] If the flow line is developed, the toughness of the corresponding portion may be improved. That is, if the length of the flow line formed in the portion adjacent to the shear surface is long, the toughness of the shear surface and a region around the shear surface may be high.

[0129] The holes 110a and 110b may be used as reference holes (tooling holes). For example, after the hot stamping component 1000 is secured to a tool using the holes 110a and 110b formed in the hot stamping component 1000 as a guide pattern (or reference point), subsequent processes such as additional hole formation, outer portion cutting, and dimensional quality inspection may be performed. In addition, the holes 110a and 110b formed in the hot stamping component 1000 may be used as guide patterns (or, reference points) for the sub-assembly process and the self-assembly process. The holes 110a and 110b formed in the hot stamping component 1000 are repeatedly seated in the tool, but if the toughness of the holes 110a and 110b formed in the hot stamping component 1000 and the region around the holes 110a and 110b is low, the hot stamping component 1000 may be damaged or the tool may be worn or damaged. According to an embodiment of the present disclosure, the flow lines (e.g., the first flow lines 1100) having a length of about 50 µm or more may exist around the holes 110a and 110b formed in the hot stamping component 1000, which may denote that the toughness around the holes 110a and 110b formed in the hot stamping component 1000 is high. Therefore, even if the holes 110a and 110b formed in the hot stamping component 1000 are repeatedly placed in the tool, it is possible to prevent the hot stamping component 1000 from being damaged or the tool from being worn or damaged.

[0130] FIGS. 16 and 17 are diagrams illustrating a difference according to the length of the flow lines formed around a shear surface. Specifically, FIG. 16 corresponds to a case when the length of the flow lines formed around the shear surface (e.g., the average length of the flow lines) is about 50 µm or more, and FIG. 17 corresponds to a case when the length of the flow lines formed around the shear surface (e.g., the average length of the flow lines) is about 50 µm or less. That is, FIG. 16 corresponds to a case when the flow lines (e.g., the first circuit lines 1100) formed in a portion adjacent to a shear surface by which the hole 110 is defined have an average length of about 50 µm or more, and FIG. 17 corresponds to a case when the flow lines (e.g., the second flow lines 1200) formed in a portion adjacent to a shear surface by which the additional hole 120 and / or the edge 130 are defined have an average length of less than about 50 µm.

[0131] Referring to FIG. 16, when an arbitrary quadrilateral is drawn along start and end points of the flow line formed on a periphery of the shear surface, if a length of a straight line AB of an edge of the shear surface is L1 and a length of a straight line CD inside the hot stamping component is L2, L2 / L1 may be about 1.2 to about 5.0. In addition, when an acute angle between the two diagonals AC and BD is θ1, θ1 may be about 10 degrees to about 45 degrees.

[0132] On the other hand, referring to FIG. 17, when an arbitrary quadrilateral is drawn along start and end points of the flow line formed on a periphery of the shear surface, if a length of a straight line A'B' of an edge of the shear surface is L3 and a length of a straight line C'D' inside the hot stamping component is L4, L4 / L3 may have a value close to about 1. For example, L4 / L3 may be less than or equal to about 1.2. In addition, when the acute angle between the two diagonals A'C' and B'D' is θ2, θ2 may be about 0 degrees to about 10 degrees.

[0133] That is, when the length of the flow line formed around the shear surface is long, the straight line at the edge of the shear surface is shorter than the straight line inside the hot stamping component, and when the length of the flow line formed around the shear surface is short, the straight line at the edge of the shear surface may be provided with a similar length to the straight line inside the hot stamping component. In addition, when the length of the flow line formed around the shear surface is long, an acute angle between the two diagonals of any quadrilateral may be provided to be greater than when the length of the flow line formed around the shear surface is short.

[0134] Accordingly, when the flow lines (e.g., the first flow lines 1100) formed in a portion adjacent to the shear surface by which the holes 110 are defined have an average length of about 50 µm or more, a straight line of the edge of the shear surface may be provided shorter than a straight line inside the hot stamping component, and an acute angle among angles between the two diagonals may be provided to be about 10 degrees to about 45 degrees. In addition, if the flow lines (e.g., the second flow lines 120)) formed in a portion adjacent to the shear surface by which the additional hole 120 and / or the edge 130 are defined have an average length of less than about 50 µm, a straight line of the edge of the shear surface may be provided with a length similar to that of a straight line inside the hot stamping component, and an acute angle between the two diagonals may be provided with an angle of about 0 degrees to about 10 degrees.

[0135] FIGS. 18 and 19 are plan views showing the effect when applying the manufacturing method according to an embodiment of the present disclosure.

[0136] Referring to FIGS. 18 and 19, it may be confirmed that when hot piercing is not performed during hot forming (or hot pressing) in a coil raw material of the same area, five blanks 100 may be obtained, but when hot piercing is performed during hot forming (or hot pressing), six blanks 100 may be obtained. That is, when hot piercing is performed during hot forming (or hot pressing), the number of blanks 100 that may be obtained from the coil raw material of the same area may increase and the amount of scrap may be reduced compared to when hot piercing is not performed during hot forming (or hot pressing).

[0137] Therefore, when hot piercing is not performed during hot forming (or hot pressing), the size of the blank 100 used in the method of manufacturing a hot stamping component may become larger than necessary compared to a final product, which may reduce the material yield, and when hot piercing is performed during hot forming (or hot pressing), the size of the blank 100 used in the method of manufacturing a hot stamping component may be prevented from becoming larger than necessary compared to the final product, which may increase the material yield.

[0138] While the disclosure has been described with reference to the embodiments shown in the drawings, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the inventive concept. Accordingly, the scope of the disclosure is defined not by the detailed description of the disclosure but by the appended claims.

Claims

1. A method of manufacturing a hot stamping component, the method comprising: preparing a blank; heating the blank; transferring the heated blank to a press mold; forming and first piercing the transferred blank by hot-pressing the transferred blank into a shape of a hot stamping component and forming at least two holes in the transferred blank; and trimming the formed blank by cutting an outer portion of the formed blank using the at least two holes.

2. The method of claim 1, wherein the preparing of the blank includes cutting a coil into the blank using a laser or a cold press mold.

3. The method of claim 1, wherein the blank includes an outer portion of the coil.

4. The method of claim 1, wherein, in the heating of the blank, the blank is heated to a temperature of Ac3 to 1000 °C.

5. The method of claim 1, wherein a temperature of the blank prior to the forming and first piercing is higher than an Ms temperature.

6. The method of claim 1, wherein in the forming and first piercing, the transferred blank is cooled within the press mold.

7. The method of claim 6, wherein the transferred blank is cooled for 3 seconds or more and 20 seconds or less.

8. The method of claim 1, wherein the trimming includes cutting an outer portion of the formed blank using a laser or a cold press mold.

9. The method of claim 1, further comprising second piercing the formed blank by forming an additional hole in the formed blank using the at least two holes.

10. The method of claim 1, further comprising, after the trimming, removing burrs formed on the blank.

11. A hot stamping component comprising: a first shear surface by which a first hole is defined; and a second shear surface formed on an edge of the hot stamping component, wherein a first flow line having a first length is formed in a portion adjacent to the first shear surface, and a second flow line or a first diagonal pattern having a second length that is less than the first length is formed in a portion adjacent to the second shear surface.

12. The hot stamping component of claim 11, wherein the first length is 50 µm or more, and the second length is less than 50 µm.

13. The hot stamping component of claim 11, further comprising a third shear surface by which a second hole spaced apart from the first hole is defined.

14. The hot stamping component of claim 13, further comprising a third flow line or a second diagonal pattern having a third length that is less than the first length in a portion adjacent to the third shear surface.

15. The hot stamping component of claim 11, further comprising a fourth shear surface by which a third hole spaced apart from the first hole is defined.

16. The hot stamping component of claim 15, further comprising a fourth flow line having a fourth length that is greater than the second length in a portion adjacent to the fourth shear surface.

17. The hot stamping component of claim 11, wherein an edge of the hot stamping component has a curved shape.

18. The hot stamping component of claim 17, wherein the hot stamping component includes a plating layer, and the plating layer is provided along the edge of the hot stamping component.

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