Blank manufacturing method

Abstract

A method for manufacturing a blank is provided that can improve production efficiency while ensuring the shape accuracy of a portion that will become a welding line. [Solution] The blank manufacturing method is for manufacturing blanks for tailored blanks, and includes a laser blanking process (step S1) in which a metal plate is irradiated with laser light to cut out a blank element from the metal plate, leaving a cutting allowance in the area that will become the welding line of the blank, and a cutting process (step S2) after the laser blanking process in which the cutting allowance is cut off from the blank element by shearing with a shearing blade to obtain the blank.

Description

[Technical Field]

[0001] The present invention relates to a blank manufacturing method for manufacturing a blank for a tailored blank. [Background technology]

[0002] In recent years, the diversification of customer needs has led to an increasing demand for small-lot, high-mix production (manufacturing many products with different specifications in small lots within the same factory or production line). It is difficult to flexibly meet such demands using press processing (die cutting) that uses dies. For this reason, blanks are cut out by laser blanking to enable flexible response to small-lot, high-mix production (Patent Document 1). Laser blanking is a processing method in which a metal plate is irradiated with a laser beam to cut out blanks from the metal plate.

[0003] Also known is a tailored blank in which a plurality of blanks (steel plates) having different material strengths and plate thicknesses are butt-welded (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-196655 [Patent Document 2] Japanese Patent Application Publication No. 2019-181523 Summary of the Invention [Problem to be solved by the invention]

[0005] In laser blanking, the faster the cutting speed, the lower the cutting accuracy tends to be. For this reason, when cutting out blanks using laser blanking, the cutting speed is generally determined so as to ensure the strictest shape accuracy.

[0006] It is possible to cut out blanks for tailored blanks using laser blanking. Since the highest shape accuracy is required for the areas that will become weld lines in tailored blanks, the cutting speed is set to ensure the shape accuracy of the areas that will become weld lines. This results in areas other than the areas that will become weld lines being cut at unnecessarily low speeds, resulting in poor production efficiency.

[0007] The present invention has been made to solve the above-mentioned problems, and one of its objects is to provide a method for manufacturing a blank that can improve production efficiency while ensuring the shape accuracy of the portion that will become the weld line. [Means for solving the problem]

[0008] The inventors conducted various studies and discovered the following new findings. Specifically, they found that by using laser blanking to cut out a blank from a metal plate while leaving a cutting allowance at the portion that will become the weld line, it is possible to cut the entire periphery of the blank at a higher speed, improving production efficiency, compared to when the cutting speed is set to match the portion that will become the weld line. They also found that by shearing off the cutting allowance from the blank by using a shear blade, it is possible to ensure the shape accuracy of the portion that will become the weld line. The present invention was made based on these new findings.

[0009] [1] In one embodiment, the present invention relates to a method for manufacturing blanks for manufacturing tailored blanks, the method including: a laser blanking step of irradiating a metal plate with laser light to cut out a blank element from the metal plate, leaving a cutting allowance in a portion that will become a welding line of the blank; and a cutting step of, after the laser blanking step, cutting off the cutting allowance from the blank element by shearing with a shearing blade to obtain the blank.

[0010] [2] The present invention may relate to the method for manufacturing a blank according to the first aspect, wherein the tailored blank is a blank for an automobile frame member. [Effects of the Invention]

[0011] According to one embodiment of the blank manufacturing method of the present invention, a laser blanking process is performed to cut out a blank body from a metal plate, leaving a cutting allowance at the portion that will become the weld line of the blank, and after the laser blanking process, the cutting allowance is sheared off from the blank body by a shearing blade to obtain the blank, thereby improving production efficiency while ensuring the shape accuracy of the weld line. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a flowchart illustrating a method of manufacturing a blank according to an embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram schematically showing the laser blanking step of FIG. 1. [Figure 3] FIG. 2 is an explanatory view schematically showing the cutting step of FIG. 1. [Figure 4] 4 is a plan view showing the blank and the cutting margin in a state where the cutting margin has been cut off from the blank element body of FIG. 3. FIG. [Figure 5] 2 is a plan view showing a tailored blank 4 using the blank 1 obtained by the method for manufacturing the blank 1 of FIG. 1. FIG. [Figure 6] FIG. 6 is a cross-sectional view of the tailored blank taken along line VI-VI in FIG. 5. [Figure 7] FIG. 6 is a perspective view showing an automobile frame member obtained by three-dimensionally forming the tailored blank of FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to each embodiment, and the components can be modified and embodied without departing from the spirit of the present invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in each embodiment. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components of different embodiments may be appropriately combined.

[0014] Figure 1 is a flowchart showing a method for manufacturing a blank 1 according to an embodiment of the present invention, Figure 2 is an explanatory diagram showing the laser blanking process (step S1) of Figure 1, Figure 3 is an explanatory diagram showing the cutting process (step S2) of Figure 1, and Figure 4 is a plan view showing the blank 1 and the cutting allowance 13 in a state where the cutting allowance 13 has been cut off from the blank body 1R of Figure 3. FIG. 5 is a plan view showing a tailored blank 4 using the blank 1 obtained by the manufacturing method of the blank 1 of FIG. 1, and FIG. 6 is a cross-sectional view of the tailored blank 4 taken along line VI-VI of FIG. FIG. 7 is a perspective view showing an automobile frame member obtained by three-dimensionally forming the tailored blank 4 of FIG.

[0015] The method for manufacturing the blank 1 in this embodiment is a method for manufacturing the blank 1 (see FIG. 4) for the tailored blank 4 (see FIG. 5). Hereinafter, the method for manufacturing the blank 1 may be simply referred to as the method. As shown in FIG. 1, the method in this embodiment includes a laser blanking step (step S1) and a cutting step (step S2).

[0016] The laser blanking step (step S1) is a step of irradiating a metal plate 10 with a laser beam 11 to cut out a blank element 1R from the metal plate 10, leaving a cutting allowance 13 at a portion 12 that will become a welding line of the blank 1.

[0017] The metal plate 10 is typically a steel plate. However, other metal plates, such as an aluminum plate, may also be used as the metal plate 10. A laser beam 11 is irradiated onto the metal plate 10 from a laser nozzle 110 disposed facing the metal plate 10. The irradiation position of the laser beam 11 (i.e., the cutting position on the metal plate 10) is changed by relative displacement between the laser nozzle 110 and the metal plate 10. The blank element 1R is an intermediate body for obtaining the blank 1 (the shaded area in FIG. 1 ), and is obtained by adding a cutting margin 13 to the blank 1. The portion 12 to become the weld line is the portion where the blank 1 is butt-welded to another blank 3 (see FIG. 5 ). Because the cutting margin 13 remains in the portion 12 to become the weld line, the portion 12 to become the weld line does not appear as an end face in the blank element 1R. The portion 12 to become the weld line extends linearly. Both ends 12a of the portion 12 to become the weld line are included in the side ends 1a of the blank 1. The cutting margin 13 is an extension of the blank 1 in the extending direction D1 of the side end 1a.

[0018] The cutting process (step S2) is a process that follows the laser blanking process (step S1) and involves shearing with a shear blade 20 to cut off the cutting allowance 13 from the blank element 1R to obtain the blank 1. As shown in Fig. 3, the shear blade 20 is inserted into the blank element 1R placed on a base 21 to cut off the cutting allowance 13. The shear blade 20 is also called a shear.

[0019] Here, in laser blanking, the faster the cutting speed, the lower the cutting accuracy tends to be. If the portion 12 to become the weld line were to be cut out by laser blanking without leaving the cut allowance 13, the cutting speed would be set to ensure the shape accuracy of the portion 12 to become the weld line (the portion requiring the strictest shape accuracy). In this case, portions other than the portion 12 to become the weld line would be cut at an unnecessarily low speed, resulting in poor production efficiency. In contrast, in the method of the present embodiment, the blank element 1R is cut out from the metal plate 10 by laser blanking, leaving the cut allowance 13 at the portion 12 to become the weld line. This allows the entire periphery of the blank element 1R to be cut at a high speed compared to when the cutting speed is set to match the portion 12 to become the weld line, thereby improving production efficiency. Furthermore, by shearing the blank element 1R by the shear blade 20 and cutting off the cut allowance 13, the shape accuracy of the portion 12 to become the weld line can be ensured.

[0020] When multiple blank elements 1R are stacked, the cutting margins 13 of each may be cut off together using the shear blade 20. This reduces the time required to cut the cutting margins 13, further improving production efficiency. The more blank elements 1R are stacked, the more production efficiency can be improved. However, if too many blank elements 1R are stacked, the shape accuracy of the portion 12 that will become the weld line may decrease. The maximum number of blank elements 1R to be stacked is determined based on the shearing capacity of the shear blade 20. Although not limited to this, it is assumed that the thickness of the cutting target that can ensure shearing accuracy using the shear blade 20 is 20 mm, and that the thickness of each blank element 1R is 0.6 mm to 3.2 mm. When the thickness of each blank element 1R is 0.6 mm, the maximum number of blank elements 1R to be stacked is 33, and when the thickness of each blank element 1R is 3.2 mm, the maximum number of blank elements 1R to be stacked is 6.

[0021] As shown in FIG. 5, the blank 1 obtained by the method of this embodiment is butt-welded to another blank 3 to form a tailored blank 4. In the illustrated embodiment, one other blank 3 is butt-welded to the blank 1, but two or more other blanks 3 may be butt-welded to the blank 1. The other blank 3 may be obtained by the method of this embodiment or by another method. The material strength and / or thickness of the blank 1 may be different from the material strength and / or thickness of the other blank 3. Although the other blank 3 is shown as being thicker than the blank 1 in FIG. 6, the blank 1 may also be thicker than the other blank 3. As particularly shown in FIG. 6, a weld metal 5 constituting a weld line is provided between the blank 1 and the other blank 3.

[0022] The tailored blank 4, the blank 1, and the other blank 3 are flat members. For example, by subjecting the tailored blank 4 to a three-dimensional forming process such as hot stamping, a three-dimensional formed product 6 as shown in FIG. 7 is obtained.

[0023] The tailored blank 4 of this embodiment is a blank for an automobile frame member. Examples of automobile frame members include frames, cross members, inside panels, pillars, dash panels, floors, and trunk floors. As an example, FIG. 5 shows a tailored blank 4 as a blank for a pillar, and FIG. 7 shows a molded product 6 as a pillar. While FIG. 7 shows a center pillar, other pillars such as front pillars may also be used. The thickness of a blank for an automobile frame member is thicker than that of other components, such as automobile exterior components (exterior panels such as roofs and doors), and the thicker the blank, the longer the time required for laser blanking. The method of this embodiment, which reduces the time required for laser blanking, is particularly useful for manufacturing blanks for automobile frame members. The thickness of the metal sheet 10 can be, for example, 0.1 mm or more and 6.0 mm or less. When the tailored blank 4 is a blank for an automobile part, the thickness of the metal sheet 10 is, for example, 0.3 mm or more and 5.0 mm or less. When the tailored blank 4 is a blank for an automobile frame member, the thickness of the metal sheet 10 is, for example, 0.6 mm or more and 4.0 mm or less. When the tailored blank 4 is a blank for an automobile frame member, the lower limit of the thickness of the metal sheet 10 may be 0.9 mm or 1.0 mm. Furthermore, when the tailored blank 4 is a blank for an automobile frame member, the upper limit of the thickness of the metal sheet 10 may be 3.5 mm or 3.0 mm. For example, when the tailored blank 4 is a blank for a pillar, the thickness of the metal sheet 10 may be 1.4 mm or more and 2.5 mm or less. For example, when the tailored blank 4 is a blank for a cross member, the thickness of the metal sheet 10 may be 1.2 mm or more and 2.0 mm or less.

[0024] Blanks for automobile frame members have a relatively long circumference per weight, and the production volume per unit time of laser blanking tends to be low. The method of this embodiment, which reduces the time required for laser blanking, is particularly useful for manufacturing blanks for automobile frame members.

[0025] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0026] For example, in the embodiment, the tailored blank 4 is described as a blank for an automobile frame member, but the tailored blank may be another blank, such as a blank for an automobile exterior member. [Explanation of symbols]

[0027] 1: Blank 1R: Blank body 4: Tailored Blank 10: Metal plate 11: Laser light 12: Part 13: Cutting allowance 20: Shear blade

Claims

1. A blank manufacturing method for manufacturing a blank for a tailored blank, comprising: a laser blanking process in which a metal plate is irradiated with a laser beam to cut out a blank element from the metal plate, leaving a cutting allowance in a portion that will become a welding line of the blank; a cutting step of cutting off the cutting allowance from the blank body by shearing with a shear blade to obtain the blank after the laser blanking step; Including, Method of manufacturing blanks.

2. The blank manufacturing method according to claim 1 , wherein the tailored blank is a blank for an automobile frame member.

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