Tailored blanks and methods for manufacturing tailored blanks

Abstract

In the manufacturing of tailored blanks, this technology can suppress the occurrence of welding defects in butt welding of steel plate blanks, including corners, and reduce the overall burden of the manufacturing process for tailored blanks, including the burden of managing the processing accuracy of the corners of the blank material. [Solution] The method for manufacturing a tailored blank includes the steps of: preparing a first steel plate 10 having a first pair of straight sides (11, 12) that taper on either side of a bottom 13 and form a recess C; preparing a second steel plate 20 having a second pair of straight sides (21, 22) that taper on either side of a top 23 and form a convex portion P with the same taper angle as the first steel plate 10; butting the first pair of straight sides and the second pair of straight sides together with a gap G already formed between the bottom 13 and the top 23; and line welding the straight sides that are butted together between the first pair of straight sides and the second pair of straight sides.

Description

Technical Field

[0001] The present disclosure relates to a tailored blank and a method for manufacturing a tailored blank.

Background Art

[0002] Conventionally, as disclosed in Patent Document 1, it is known to manufacture a tailored blank having partially different specifications by integrating blanks with different specifications such as plate thickness and strength of steel plates with each other through butt welding. Patent Document 1 discloses a state where a corner portion is formed in a boundary line between blanks having different specifications from each other.

[0003] The corner portion is formed by two sides (for example, a first side and a second side) that respectively form the outer edge of a steel plate of one blank. The corner portion includes an intersection of two sides intersecting each other and a periphery around the intersection. In the corner portion of Patent Document 1, a pair of blanks are welded in a state where they are butted against each other without a gap. When the plate surface of the steel plate of the blank is viewed from the front, the shape of the butt weld at the corner portion is bent including the intersection of the two sides.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] In the case where continuous butt welding is performed from the first side to the second side without interruption at a bent corner portion as in Patent Document 1, there is a concern that welding quality may be deteriorated. Specifically, it is actually very difficult to pre-form the shape and dimensions of the respective side surfaces (end faces) of a pair of steel plates at the corner portion including the intersection before butt welding so that the side surfaces abut against each other without a gap.

[0006] This is partly because, when manufacturing the blanks that make up tailored blanks, high processing accuracy is required on the sides of the corners during processing such as cutting, which involves cutting out the corners from the steel plate material. For this reason, if the processing accuracy of the sides of the corners is not adequately controlled, for example, if there are many gaps in the interface between the sides of the steel plates of the butt-jointed blanks, welding defects such as burn-through may occur at the butt weld joint of the corner, resulting in a decrease in welding quality.

[0007] As a method to suppress the reduction in welding quality while reducing the burden of managing the machining accuracy of the corners and sides, one possible method is to manufacture a tailored blank by repeatedly performing linear butt welding multiple times. In other words, by repeating linear butt welding (i.e., splicing) between relatively small steel plate blanks that do not have inwardly recessed areas the required number of times, a tailored blank with a relatively large area and recessed areas is ultimately manufactured.

[0008] However, in a method that involves repeatedly butting together blanks that do not have recesses in a straight line, the number of additional welds required to finally manufacture a tailored blank increases. This leads to the problem of an overall increase in the burden of manufacturing tailored blanks.

[0009] This disclosure has been made in view of the above, and provides a technology that can suppress the occurrence of welding defects in butt welding of steel plate blanks including corners in the manufacturing of tailored blanks, and can reduce the overall burden of the manufacturing of tailored blanks, including the burden of managing the processing accuracy of the corners of the blank material. [Means for solving the problem]

[0010] A method for manufacturing a tailored blank according to the present disclosure includes the steps of: preparing a first steel plate having a bottom and a first pair of straight sides that taper on either side of the bottom, and forming a recess with the bottom and the first pair of straight sides; preparing a second steel plate having a top and a second pair of straight sides that taper on either side of the top, having the same taper angle as the taper of the first steel plate, and forming a convex portion with the top and the second pair of straight sides; butting the corresponding straight sides between the first pair of straight sides and the second pair of straight sides with a gap already formed between the bottom and the top; and line welding the straight sides that have butted together between the first pair of straight sides and the second pair of straight sides. [Effects of the Invention]

[0011] According to this disclosure, in the manufacturing of tailored blanks, it is possible to suppress the occurrence of welding defects in butt welding of steel plate blanks, including corners, and to reduce the overall burden of the manufacturing process of tailored blanks, including the burden of managing the processing accuracy of the corners of the blank material. [Brief explanation of the drawing]

[0012] [Figure 1] This is a plan view illustrating the process of butting together a pair of steel plates in a method for manufacturing a tailored blank according to an embodiment of the present disclosure. [Figure 2] This is a plan view illustrating the process of line welding the butt joints of steel plates in the manufacturing method of tailored blanks according to this embodiment. [Figure 3] This is a plan view illustrating the process of separating the ends of the wire welded portion in the manufacturing method of a tailored blank according to this embodiment. [Figure 4] This is a plan view illustrating a tailored blank in which the ends of the wire welded portion are separated, according to the manufacturing method of tailored blanks according to this embodiment. [Figure 5] This is a perspective view illustrating the folded state of the tailored blank according to this embodiment. [Figure 6] This is a perspective view illustrating a tailored blank according to another example of this embodiment, in a state where the ends of the wire welds are bent before separation. [Figure 7] This is a plan view illustrating the process of separating the ends of the wire welded portion in a method for manufacturing a tailored blank according to a first modified example of this embodiment. [Figure 8] This is a plan view illustrating the process of butting together a pair of steel plates in a method for manufacturing a tailored blank according to a second modification of this embodiment. [Figure 9] This is a plan view illustrating the process of line welding the butt joints of steel plates in a method for manufacturing a tailored blank according to a second modified example. [Figure 10] This is a plan view illustrating the process of butting together a pair of steel plates in a method for manufacturing a tailored blank according to a third modified example of this embodiment. [Figure 11] This is a plan view illustrating the process of line welding the butt joints of steel plates in a method for manufacturing a tailored blank according to the third modified example. [Figure 12] This is a plan view illustrating the process of butting together a pair of steel plates in a method for manufacturing a tailored blank according to a fourth modified example of this embodiment. [Figure 13] This is a plan view illustrating the process of line welding the butt joints of steel plates in a method for manufacturing a tailored blank according to the fourth modified example. [Modes for carrying out the invention]

[0013] This embodiment is described below. In the following drawings, identical and similar parts are denoted by the same or similar reference numerals. However, the relationship between thickness and planar dimensions, the ratio of thickness of each device and component, etc., in the drawings may differ from reality. Therefore, specific thicknesses and dimensions should be determined by referring to the following explanation. Furthermore, there are parts where the relationships and ratios of dimensions differ between drawings. Also, unless otherwise specified in the specification, the number of each component in this disclosure is not limited to one, and there may be multiple.

[0014] <Method for producing tailored blank> First, a method for producing a tailored blank according to the present embodiment will be described with reference to FIGS. 1 to 6. The method for producing a tailored blank according to the present embodiment includes: a step of preparing a first steel plate 10; a step of preparing a second steel plate 20; a butting step of butting the first steel plate 10 and the second steel plate 20 against each other; a linear welding step of performing linear welding on the butted first steel plate 10 and second steel plate 20; and a separation step of separating an end portion of the linear welded portion from the linear welded portion. In the present disclosure, the separation step is not essential. Each step will be specifically described below.

[0015] (Step of preparing steel plates) (First steel plate) As shown in FIG. 1, the first steel plate 10 has a bottom portion 13 and a first pair of straight sides tapered with the bottom portion 13 interposed therebetween. A recess C is formed by the bottom portion 13 and the first pair of straight sides. The pair of straight sides (the first pair of straight sides) in the first steel plate 10 includes a first concave straight side 11 on the left side in FIG. 1 and a second concave straight side 12 on the right side in FIG. 1. The first concave straight side 11 and the second concave straight side 12 are not parallel. That is, a virtual extension line of the first concave straight side 11 intersects with a virtual extension line of the second concave straight side 12. The taper angle of the taper of the first steel plate 10 is formed by the intersection angle between the virtual extension line of the first concave straight side 11 and the virtual extension line of the second concave straight side 12.

[0016] (Second steel plate) The second steel plate 20 has a top portion 23 and a second pair of straight sides that form a taper with the same taper angle as the taper of the first steel plate 10, flanking the top portion 23. In this disclosure, "two tapers having the same taper angle" means that the difference between the two tapers is 2 degrees or less. The top portion 23 and the second pair of straight sides form a convex portion P. The pair of straight sides in the second steel plate 20 (the second pair of straight sides) has a convex first straight side 21 on the left side of Figure 1 and a convex second straight side 22 on the right side. The convex first straight side 21 and the convex second straight side 22 are not parallel. That is, the virtual extension of the convex first straight side 21 and the virtual extension of the convex second straight side 22 intersect. The angle of intersection between the virtual extension of the convex first straight side 21 and the virtual extension of the convex second straight side 22 forms the taper angle of the taper of the second steel plate 20.

[0017] The first concave straight edge 11 and the first convex straight edge 21 are parallel. The second concave straight edge 12 and the second convex straight edge 22 are parallel. The tapered shape of the first steel plate 10 and the tapered shape of the second steel plate 20 fit together. Here, the intersection angle between the first concave straight edge 11 and the first convex straight edge 21 is set to θ1, and the intersection angle between the second concave straight edge 12 and the second convex straight edge 22 is set to θ2. In this embodiment, the first concave straight edge 11, the first convex straight edge 21, the second concave straight edge 12, and the second convex straight edge 22 are constructed such that the sum of the intersection angles θ1 and θ2 is within 2 degrees. This creates a state where "the first concave straight edge 11 and the first convex straight edge 21 are parallel" and "the second concave straight edge 12 and the second convex straight edge 22 are parallel".

[0018] The recess C and convex P in this embodiment are trapezoidal. The trapezoids of the recess C and convex P in this embodiment are isosceles trapezoids, but this disclosure is not limited thereto, and the trapezoid may be an unequal-legged trapezoid. The bottom 13 of the first steel plate 10 and the top 23 of the second steel plate 20 correspond to the upper base of the trapezoid, respectively. The bottom 13 and top 23 in this embodiment are parallel. The trapezoids of the recess C and convex P in this embodiment are trapezoids in which the upper base is shorter than the lower base. In other words, in this embodiment, the shape of the recess C and convex P is a trapezoid in which the opening width measured along the left-right direction decreases as you move from the upper bottom 13 to the lower opening in Figure 1.

[0019] In this embodiment, a tailored blank is exemplified as being constructed from two steel plates, but in this disclosure, a tailored blank may be constructed from three or more steel plates. In this embodiment, a case where the bottom 13 is a straight edge is exemplified, but in this disclosure, the bottom 13 is not limited to a straight edge and may include a corner, i.e., a base point. In this disclosure, the corner may be pointed or curved.

[0020] (Butt joint process) Next, the pair of steel plates are butted together as shown by the upward arrow in Figure 1. In this disclosure, the lower second steel plate 20 in Figure 1 is shown to be close to the upper first steel plate 10, but this disclosure is not limited to this. The upper first steel plate 10 may be close to the lower second steel plate 20, or both the lower second steel plate 20 and the upper first steel plate 10 may be close to each other.

[0021] The corresponding straight edges between the first pair of straight edges, the concave first straight edge 11 and the concave second straight edge 12, and the second pair of straight edges, the convex first straight edge 21 and the convex second straight edge 22, are abutted together with a gap G pre-formed between the bottom 13 and the top 23. In this embodiment, the gap G is formed by the concave first straight edge 11, the concave second straight edge 12, the bottom 13, and the top 23.

[0022] (Wire welding process) Next, as shown in Figure 2, the butt joint between the first steel plate 10 and the second steel plate 20 is line-welded. Specifically, the straight edges that butt against each other between the pair of straight edges of the first steel plate 10 (concave first straight edge 11, concave second straight edge 12) and the pair of straight edges of the second steel plate 20 (convex first straight edge 21, convex second straight edge 22) are line-welded, thereby forming a pair of linear line-welded sections in the tailored blank 100 of this embodiment. The pair of line-welded sections has a first line-welded section 31 on the left side and a second line-welded section 32 on the right side in Figure 2. Line welding includes laser welding and arc welding. In either laser welding or arc welding, build-up welding may or may not be performed. In Figure 2, the pair of line-welded sections are illustrated by thick straight lines.

[0023] (separation process) Next, as shown in Figure 3, the ends of the linear welds on the straight edges are separated from the linear welds. Specifically, in this embodiment, the separation process is carried out by piercing or trimming. However, in this disclosure, the separation process is not limited to piercing or trimming, and any known cutting method, such as a laser method, can be used as appropriate. In trimming, the start and end points may be separated by cutting an area that includes the entire outer edge of the gap G, or by partially cutting an area that overlaps with the start and end points and is part of the outer edge of the gap G.

[0024] In Figure 3, a dashed piercing separation line L1, which has an elliptical shape and includes a gap G, is illustrated in the central part of the tailored blank 100. In this disclosure, the shape of the piercing separation line is not limited to an elliptical shape and can be changed as appropriate to a circular shape, etc. By piercing along the piercing separation line L1, the upper ends of the first line weld 31 on the left and the second line weld 32 on the right in Figure 3 are separated from the first line weld 31 and the second line weld 32, respectively.

[0025] In Figure 3, a straight, dashed trim separation line L2 is shown at the bottom of the tailored blank 100, extending parallel to the bottom 13. In this disclosure, the shape of the trim separation line is not limited to a straight line and can be changed as appropriate. Also, the direction in which the trim separation line extends is not limited to extending parallel to the bottom 13 and can be arbitrary. By trimming along the trim separation line L2, the lower ends of each of the pair of wire welds in Figure 3 are separated from each other.

[0026] Figure 4 illustrates a tailored blank 100 with the ends of the wire weld separated. An elliptical piercing hole H is formed in the center of the tailored blank 100. In this embodiment, the case in which both ends of the wire weld are separated from the wire weld in both the first wire weld 31 and the second wire weld 32 is illustrated, but this disclosure is not limited to this. In this disclosure, it is sufficient for at least one end of the wire weld to be separated in at least one of the wire welds. However, separating both ends of the wire weld from the wire weld in each of the welds, as indicated by the two white arrows in Figure 3, as in this embodiment, is preferable in that it can suppress the occurrence of welding defects.

[0027] (Folding process) Next, as shown in Figure 5, the tailored blank 100 is bent according to the shape of a predetermined member for which the tailored blank 100 is required as a material, such as a pillar member for an automobile. In this embodiment, the bending process is exemplified as being performed after the separation process, but in this disclosure, the order in which the separation process and the bending process are performed is not limited. As shown in Figure 6, the bending process may be performed after the wire welding process, and a separation process may be performed on the ends of the wire welded portion of the bent tailored blank 100.

[0028] (Effects and Benefits) In the manufacturing method of tailored blanks according to this embodiment, a gap G is formed in advance between the bottom 13 of the recess C and the top 23 of the convex P. Therefore, the first steel plate 10 and the second steel plate 20 do not butt together at the corner of the recess C. As a result, in butt welding of steel plate blanks including corners, two straight butt joints are formed as the welding target area, while no bent butt joint is formed. Therefore, in the manufacturing of tailored blanks 100, the occurrence of welding defects in butt welding of steel plate blanks including corners can be suppressed.

[0029] Furthermore, when pre-fabricating the blanks that make up Tailored Blank 100, high processing accuracy is not required for the sides of the corners during processing such as cutting, which involves cutting out blanks with corners from the steel plate material. Therefore, in the manufacturing of Tailored Blank 100, the burden of managing the processing accuracy of the corners of the blank material can be reduced.

[0030] Furthermore, butt welding can be performed using a blank with a recess C without having to repeatedly perform linear butt welding on blanks that do not have a recess C. Therefore, in the manufacturing of tailored blanks 100, the occurrence of welding defects in butt welding of steel plate blanks including corners can be suppressed, and the overall burden of manufacturing tailored blanks 100, including the burden of managing the processing accuracy of the corners of the blank material, can be reduced.

[0031] Here, for example, one could consider a method of manufacturing a tailored blank in which the concave part of the first steel material and the convex part of the second steel material are finally combined by repeatedly performing linear butt welding. However, in a method of repeatedly performing linear butt welding of blanks that do not have concave parts, the number of additional welds required before the tailored blank is finally manufactured increases. In addition, prior to welding the joined blanks together, the ends of the blanks may need to be trimmed or otherwise shaped in advance to align the butt joints that will be welded in a straight line, and this work may occur each time additional welding is performed. As a result, the overall burden of manufacturing the tailored blank increases. In this embodiment, however, the burden of manufacturing work caused by additional welding is not incurred.

[0032] Similarly, it is possible to create a tailored blank 100 that can suppress the occurrence of welding defects in butt welding of steel plate blanks including corners, and reduce the overall burden of manufacturing the tailored blank 100, including the burden of managing the processing accuracy of the corners of the blank material.

[0033] Furthermore, in this embodiment, the occurrence of welding defects at the corners of the recess C can be suppressed, making it easier to manufacture tailored blanks 100 with various configuration patterns including corners. For example, by using tailored blanks 100 in a structural member, it is easier to improve the controllability of the structural member when controlling the deformation of the structural member.

[0034] Furthermore, in this embodiment, since the ends of the wire weld, which are more prone to welding defects than the central part, are separated, the occurrence of welding defects is further suppressed.

[0035] Furthermore, in this embodiment, the ends of the welded portion can be trimmed by piercing or trimming.

[0036] Next, a method for manufacturing tailored blanks according to the first to fourth modified examples of this embodiment will be described with reference to Figures 7 to 13.

[0037] (First variation) In this embodiment, the second steel plate 20 had a shape and dimensions that protruded outward from the recess C, but this disclosure is not limited thereto. For example, as shown in Figure 7, in the tailored blank 100A according to the first modification, the second steel plate 20A may have a shape and dimensions such that it is held inside the recess C of the first steel plate 10 without protruding outward from the recess C. In the first modification, even if the second steel plate 20A has a shape and dimensions that are held inside the recess C of the first steel plate 10, a gap G is formed when the first steel plate 10 and the second steel plate 20A are abutted together.

[0038] The other components of the tailored blank 100A according to the first modified example are the same as those of the tailored blank 100 according to this embodiment, so a redundant explanation is omitted. Also, the effects of the tailored blank 100A according to the first modified example are the same as those of the tailored blank 100 according to this embodiment, so a redundant explanation is omitted.

[0039] (Second variation) In this embodiment, the trapezoidal shapes of the recess C and protrusion P were trapezoidal in that the upper base was shorter than the lower base, but this disclosure is not limited to this. For example, as shown in Figures 8 and 9, in the tailored blank 100B according to the second modification, the trapezoidal shapes of the recess C of the first steel plate 10B and the protrusion P of the second steel plate 20B may be trapezoidal in that the lower base is shorter than the upper base. In other words, in the second modification, the shape of the recess C and protrusion P is an inverted trapezoid in which the opening width measured along the left-right direction decreases as you move from the upper bottom 13 in Figure 8 towards the lower opening. In the second modification, even if the shape of the recess C and protrusion P is an inverted trapezoid, a gap G is formed when the first steel plate 10B and the second steel plate 20B are butted together.

[0040] Furthermore, in this embodiment, the protrusion P is exemplified as the portion of the second steel plate 20 that fits with the recess C, but this disclosure is not limited to this. As shown in the second modified example in Figures 8 and 9, the entire upper part of the second steel plate 20B may be a protrusion. In this disclosure, the entire second steel plate may be a protrusion.

[0041] The other components of the tailored blank 100B according to the second modified example are the same as those of the tailored blank 100 according to the present embodiment, so a redundant explanation is omitted. Also, the effects of the tailored blank 100B according to the second modified example are the same as those of the tailored blank 100 according to the present embodiment, so a redundant explanation is omitted.

[0042] (Third variation) In this embodiment, the bottom 13 and top 23 were parallel, but this disclosure is not limited to this. For example, as shown in Figures 10 and 11, the bottom 13 and top 23C may intersect. In the tailored blank 100C according to the third modified example, even if the virtual extension line of the bottom 13 of the first steel plate 10 and the virtual extension line of the top 23C of the second steel plate 20C intersect, a gap G is formed when the first steel plate 10 and the second steel plate 20C are butted together.

[0043] The other components of the tailored blank 100C according to the third modified example are the same as those of the tailored blank 100 according to this embodiment, so a redundant explanation is omitted. Also, the effects of the tailored blank 100C according to the third modified example are the same as those of the tailored blank 100 according to this embodiment, so a redundant explanation is omitted.

[0044] (Fourth variation) In this embodiment, the bottom portion 13 was a straight edge, but the disclosure is not limited thereto. As shown in Figures 12 and 13, in the tailored blank 100D according to the fourth modification, the bottom portion 13 of the first steel plate 10D is the bottom point. In the fourth modification, the recess C is formed by the recessed first straight edge 11, the recessed second straight edge 12D, and the bottom portion 13 which is the bottom point.

[0045] Furthermore, in this embodiment, an example was given in which the virtual extensions of the pair of tapered straight sides intersect, that is, when the recess C and the convex P are trapezoidal, but this disclosure is not limited thereto. In the fourth modified example, the pair of tapered straight sides of the recess C may actually intersect. That is, as shown in Figure 13, the gap G formed when the first steel plate 10D and the second steel plate 20D are butted together may be triangular in shape. In the fourth modified example, the gap G is formed by the first straight side 11 on the concave side, the second straight side 12A on the concave side, and the bottom point 13 and the top point 23.

[0046] Furthermore, in this embodiment, the convex portion P is exemplified as the portion of the second steel plate 20 that fits with the concave portion C, but this disclosure is not limited to this. As shown in the fourth modified example in Figure 12, the upper left portion of the second steel plate 20D may be the convex portion.

[0047] The other components of the tailored blank 100D according to the fourth modified example are the same as those of the tailored blank 100 according to this embodiment, so a redundant explanation is omitted. Also, the effects of the tailored blank 100D according to the fourth modified example are the same as those of the tailored blank 100 according to this embodiment, so a redundant explanation is omitted.

[0048] <Other Embodiments> While the embodiments described above illustrate the present disclosure, this description is not intended to limit the disclosure. Those skilled in the art should be able to see from this disclosure various alternative embodiments, examples, and operational techniques. This disclosure includes various embodiments not described above, and the technical scope of this disclosure is defined solely by the inventive features of the claims that are reasonable given the above description.

[0049] ≪Note≫ The following embodiments are conceptualized herein.

[0050] Embodiment 1 is, A step of preparing a first steel plate having a bottom portion and a first pair of straight sides that are tapered on either side of the bottom portion, wherein the bottom portion and the first pair of straight sides form a recess, A step of preparing a second steel plate having a top and a second pair of straight sides that sandwich the top and have the same taper angle as the taper of the first steel plate, wherein the top and the second pair of straight sides form a convex portion, A step of butting together the corresponding straight edges between the first pair of straight edges and the second pair of straight edges, with a gap pre-formed between the bottom and the top, A step of line welding each of the straight sides that are butted against each other between the first pair of straight sides and the second pair of straight sides, A method for manufacturing tailored blanks, including [the specified part of the method].

[0051] Embodiment 2 is, The process further includes separating the end of the line weld of the straight edge from the line weld, A method for manufacturing a tailored blank according to Embodiment 1.

[0052] Embodiment 3 is, The separation process is carried out by piercing or trimming. A method for manufacturing a tailored blank according to Embodiment 2.

[0053] Appearance 4 is, A first steel plate having a bottom and a first pair of tapered straight sides flanking the bottom, the bottom and the first pair of straight sides forming a recess, A second steel plate having a top portion and a second pair of straight sides that sandwich the top portion and have the same taper angle as the taper of the first steel plate, and which are abutted against each of the corresponding first pair of straight sides with a gap already formed between the bottom portion and the top portion, and the top portion and the second pair of straight sides form a convex portion, A pair of line welds formed on each of the straight sides that are butted against each other between the first pair of straight sides and the second pair of straight sides, A tailored blank equipped with [specific features / features]. [Explanation of Symbols]

[0054] 10,10B,10D Daiichi Steel Plate 11. First straight edge on the concave side 12. Second straight edge on the concave side 12A Concave side, second straight edge 13 Bottom 20,20A,20B,20C,20D Second steel plate 21 Convex first straight edge 22 Convex side, second straight edge 23 Top 31. First-line welding section 32 Second line weld 100, 100A, 100B, 100C, 100D Tailored Blanks C recess G Gap H Piercing L1 Piercing Separation Line L2 Trim Separation Line P protrusion

Claims

1. A step of preparing a first steel plate having a bottom portion and a first pair of straight sides that are tapered on either side of the bottom portion, wherein the bottom portion and the first pair of straight sides form a recess, A step of preparing a second steel plate having a top and a second pair of straight sides that sandwich the top and have the same taper angle as the taper of the first steel plate, wherein the top and the second pair of straight sides form a convex portion, A step of butting together the corresponding straight edges between the first pair of straight edges and the second pair of straight edges, with a gap pre-formed between the bottom and the top, A step of line welding each of the straight sides that are butted against each other between the first pair of straight sides and the second pair of straight sides, A method for manufacturing tailored blanks, including [the specified part of the method].

2. The process further includes separating the end of the line weld of the straight edge from the line weld, A method for manufacturing a tailored blank according to claim 1.

3. The separation process is carried out by piercing or trimming. A method for manufacturing a tailored blank according to claim 2.

4. A first steel plate having a bottom and a first pair of tapered straight sides flanking the bottom, the bottom and the first pair of straight sides forming a recess, A second steel plate having a top portion and a second pair of straight sides that sandwich the top portion and have the same taper angle as the taper of the first steel plate, and which are abutted against each of the corresponding first pair of straight sides with a gap already formed between the bottom portion and the top portion, and the top portion and the second pair of straight sides form a convex portion, A pair of line welds formed on each of the straight sides that are butted against each other between the first pair of straight sides and the second pair of straight sides, A tailored blank equipped with [specific features / features].

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