Quenching method and quenching device

Abstract

To provide a technology for suppressing scattering of laser light caused by cooling water when quenching a press-formed product.SOLUTION: A quenching method of a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bent portion connecting the first wall portion and the second wall portion includes heating the bent portion by irradiating the bent portion with a laser beam, and cooling the heated bent portion by spraying water to the bent portion following the irradiation with the laser beam. The water spraying is performed in a state where a shielding member is disposed so as to separate a laser beam irradiation region and a water spraying region.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a technique for hardening a press-formed product. [Background technology]

[0002] For example, Patent Document 1 discloses a method for quenching a steel plate, which is a workpiece, in which a heating treatment by irradiating the workpiece with a laser beam and a cooling treatment by injecting water onto the heated workpiece are performed successively. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-194132 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology described in Patent Document 1, the sprayed cooling water may be heated by the heated workpiece, generating water vapor. In such cases, the water vapor may enter the area irradiated with the laser beam and scatter the laser beam. If the water vapor scatters the laser beam, the hardening may become uneven.

[0005] One aspect of the present disclosure provides a technique for suppressing scattering of laser light caused by cooling water when hardening a press-formed product. [Means for solving the problem]

[0006] One aspect of the present disclosure is a method for quenching a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bent portion connecting the first wall portion and the second wall portion. The method for quenching a press-formed product includes heating the bent portion by irradiating the bent portion with laser light, and cooling the heated bent portion by spraying water onto the bent portion following the irradiation of the laser light. The water is sprayed in a state where a shielding member is positioned to separate the laser light irradiated area from the water sprayed area.

[0007] With this configuration, when hardening a press-molded product, scattering of laser light caused by cooling water can be suppressed.

[0008] In one aspect of the present disclosure, the water may be sprayed in a state where the shielding member is positioned so as to cover the water spray area but not the laser beam irradiation area. With this configuration, when quenching the press-formed product, scattering of the laser beam caused by the cooling water can be further suppressed.

[0009] In one aspect of the present disclosure, the water may be injected in a state where gas is sucked in the water injection area, between the laser light irradiation area and the water injection area separated by the shielding member. With this configuration, scattering of the laser light caused by the cooling water can be further suppressed when quenching the press-formed product.

[0010] In one aspect of the present disclosure, the irradiation of the laser light and the injection of the water may be performed in a state in which the first wall portion is fixed and the second wall portion is pressed toward the first wall portion. With this configuration, deformation due to hardening can be made less likely to occur.

[0011] One aspect of the present disclosure is a quenching device for a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bent portion connecting the first wall portion and the second wall portion, the quenching device including a laser irradiation unit, a water injection unit, and a cover. The laser irradiation unit is configured to irradiate the bent portion with laser light. The water injection unit is configured to inject water into the bent portion following the irradiation of the laser light. The shielding member is arranged to separate the laser light irradiation area from the water injection area.

[0012] With this configuration, when hardening a press-molded product, scattering of laser light caused by cooling water can be suppressed.

[0013] In one aspect of the present disclosure, the shielding member may be arranged to cover the water injection area but not the laser beam irradiation area. With this configuration, scattering of the laser beam due to the cooling water can be further suppressed when hardening the press-formed product.

[0014] In one aspect of the present disclosure, the laser beam irradiation area and the water injection area are separated by the shielding member, and the laser beam irradiation area and the water injection area may further include a gas suction unit configured to suck in gas on the water injection area side. With this configuration, when quenching the press-formed product, water is injected while the gas is being sucked in by the gas suction unit, thereby further suppressing scattering of the laser beam caused by the cooling water.

[0015] In one aspect of the present disclosure, the bearing may further include two fixing portions and two pressing portions. The fixing portions are arranged on both sides of the first wall portion and configured to sandwich the first wall portion. The pressing portions are arranged on both sides of the second wall portion and configured to sandwich the second wall portion. The two pressing portions may be configured to sandwich the second wall portion while pressing the second wall portion in a direction toward the first wall portion. This configuration can make it less likely for deformation due to hardening to occur. [Brief explanation of the drawings]

[0016] [Figure 1]FIG. 1 is a perspective view of a workpiece. [Figure 2] FIG. 2 is a perspective view of the workpiece and the hardening device. [Figure 3] Fig. 3A is a side view for explaining the arrangement step in the workpiece hardening method, and Fig. 3B is a cross-sectional view taken along IIIB-IIIB in Fig. 3A. [Figure 4] Fig. 4A is a side view showing the state subsequent to Fig. 3A, and Fig. 4B is a cross-sectional view taken along line IVB-IVB in Fig. 4A. [Figure 5] Fig. 5A is a side view illustrating the quenching step in the workpiece quenching method, and Fig. 5B is a cross-sectional view taken along line VB-VB in Fig. 5A. [Figure 6] Fig. 6A is a side view showing the state subsequent to Fig. 5A, and Fig. 6B is a cross-sectional view taken along line VIB-VIB in Fig. 6A. [Figure 7] Fig. 7A is a side view showing the state subsequent to Fig. 6A, and Fig. 7B is a cross-sectional view taken along line VIIB-VIIB in Fig. 7A. [Figure 8] Fig. 8A is a side view showing a state after the quenching step in the workpiece quenching method is completed, and Fig. 8B is a cross-sectional view taken along line VIIIB-VIIIB in Fig. 8A. [Figure 9] FIG. 9 is a perspective view of a workpiece and a hardening device showing a modified example of the shielding member. [Figure 10] FIG. 10 is a side view for explaining the quenching step in the workpiece quenching method using the quenching device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. Work configuration] FIG. 1 shows a workpiece 1 that is the object to be hardened in the hardening method and hardening apparatus of the present disclosure. As an example, the workpiece 1 is a component part of an automobile body. Specific examples of component parts of an automobile body include pillars and members of the automobile. Note that the directional terms used for the workpiece 1 are used to help the reader understand the present disclosure and do not limit the manner in which the workpiece 1 is used.

[0018] The workpiece 1 is a press-formed product manufactured by pressing a steel plate. The steel plate is, for example, a high-tensile steel material (so-called high-tensile material) having high tensile strength. The tensile strength of the high-tensile steel material may be, for example, 590 MPa or more, 780 MPa or more, or 980 MPa or more. In this embodiment, the tensile strength of the high-tensile steel material is 1000 MPa. The plate thickness of the high-tensile steel material is, for example, 1.0 mm to 3.0 mm.

[0019] As shown in Figure 1, the workpiece 1 extends linearly. The direction in which the workpiece 1 extends is hereinafter referred to as the extension direction X. The cross-sectional shape of the workpiece 1 perpendicular to the extension direction X is constant in the extension direction X. The cross-sectional shape of the workpiece 1 perpendicular to the extension direction X is bilaterally symmetrical.

[0020] The workpiece 1 has a top plate portion 11, a right side wall portion 12a, a left side wall portion 12b, a right bent portion 13a, a left bent portion 13b, a right flange portion 14a, and a left flange portion 14b.

[0021] The top panel 11 is a plate-like portion. Specifically, the top panel 11 has a rectangular flat plate shape when viewed from the front. The two long sides of the top panel 11 when viewed from the front are parallel to the extension direction X.

[0022] The right side wall portion 12a and the left side wall portion 12b are plate-shaped portions. Specifically, the right side wall portion 12a and the left side wall portion 12b are rectangular flat plates when viewed from the front. The two long sides of each of the right side wall portion 12a and the left side wall portion 12b when viewed from the front are parallel to the extension direction X. The right side wall portion 12a and the left side wall portion 12b face each other. Each of the right side wall portion 12a and the left side wall portion 12b intersects with the top plate portion 11. More specifically, the right side wall portion 12a or the left side wall portion 12b intersecting with the top plate portion 11 means that an imaginary plane including the right side wall portion 12a or the left side wall portion 12b intersects with an imaginary plane including the top plate portion 11. The angle θa formed between the right side wall portion 12a and the top panel portion 11 and the angle θb formed between the left side wall portion 12b and the top panel portion 11 are both, for example, greater than 90 degrees. That is, the right side wall portion 12a and the left side wall portion 12b are inclined relative to the top panel portion 11 so that the distance between them increases as they move away from the top panel portion 11.

[0023] The right bent portion 13a and the left bent portion 13b are portions bent by press working. The right bent portion 13a and the left bent portion 13b are plate-shaped and curved so that the plate thickness direction is the radial direction. The right bent portion 13a is located between the top plate portion 11 and the right side wall portion 12a. The right bent portion 13a connects the top plate portion 11 and the right side wall portion 12a. The left bent portion 13b is located between the top plate portion 11 and the left side wall portion 12b. The left bent portion 13b connects the top plate portion 11 and the left side wall portion 12b.

[0024] Hereinafter, of both surfaces of the right bent portion 13a, the radially inner surface is referred to as the inner surface, and the radially outer surface is referred to as the outer surface. Of both surfaces of the left bent portion 13b, the radially inner surface is referred to as the inner surface, and the radially outer surface is referred to as the outer surface. Of both surfaces of the right side wall portion 12a, the surface that continues to the inner surface of the right bent portion 13a is referred to as the inner surface, and the surface that continues to the outer surface of the right bent portion 13a is referred to as the outer surface. Of both surfaces of the left side wall portion 12b, the surface that continues to the inner surface of the left bent portion 13b is referred to as the inner surface, and the surface that continues to the outer surface of the left bent portion 13b is referred to as the outer surface. Of both surfaces of the top plate portion 11, the surfaces that continue to the inner surfaces of the right bent portion 13a and the left bent portion 13b are referred to as the inner surface, and the surfaces that continue to the outer surfaces of the right bent portion 13a and the left bent portion 13b are referred to as the outer surface.

[0025] The right flange portion 14a and the left flange portion 14b are plate-shaped portions. Specifically, the right flange portion 14a and the left flange portion 14b are rectangular flat plates when viewed from the front. The two long sides of each of the right flange portion 14a and the left flange portion 14b are parallel to the extension direction X. The right flange portion 14a extends outward from one of two end faces of the right side wall portion 12a extending along the extension direction X, the end face opposite the top plate portion 11. The "outward" here refers to the side opposite the top plate portion 11 across the right side wall portion 12a. In other words, the "outward" here refers to the outer surface side of the right side wall portion 12a. The left flange portion 14b extends outward from one of two end faces of the left side wall portion 12b extending along the extension direction X, the end face opposite the top plate portion 11. The outer side here refers to the side opposite the top plate 11 across the left side wall 12b. In other words, the outer side here refers to the outer surface side of the left side wall 12b. The right flange 14a and the left flange 14b extend in directions away from each other from the right side wall 12a and the left side wall 12b. The right flange 14a and the left flange 14b each extend approximately parallel to the top plate 11. Hereinafter, of both surfaces of the right flange 14a, the surface that continues onto the inner surface of the right side wall 12a will be referred to as the inner surface, and the surface that continues onto the outer surface of the right side wall 12a will be referred to as the outer surface. Of both surfaces of the left flange 14b, the surface that continues onto the inner surface of the left side wall 12b will be referred to as the inner surface, and the surface that continues onto the outer surface of the left side wall 12b will be referred to as the outer surface.

[0026] Automobile bodies require high strength, but high-strength materials are generally expensive. Therefore, as an example, localized quenching may be performed on portions of a press-formed product that require particular strength, thereby increasing the overall strength of the press-formed product. For example, in the case of workpiece 1, localized quenching is performed on right bent portion 13a and left bent portion 13b. For example, if localized quenching is performed on right bent portion 13a and left bent portion 13b of workpiece 1, which has a tensile strength of 1000 MPa before quenching, the overall tensile strength of workpiece 1 will be 1500 MPa.

[0027] [2. Configuration of the quenching equipment] The quenching device 2 shown in FIG. 2 is configured to harden the workpiece 1. Specifically, the quenching device 2 is configured to harden the right bent portion 13a and the left bent portion 13b of the workpiece 1. As shown in FIGS. 2 and 6A, the quenching device 2 includes a first top plate jig 31, a second top plate jig 32, a first side wall jig 33, a second side wall jig 34, a third side wall jig 35, a plurality of top plate cylinders 36, a plurality of side wall cylinders 37, a laser head 21, a cover 22, a water-cooled nozzle 23, and a suction nozzle 24. These components of the quenching device 2 are used in the same way when hardening the right bent portion 13a and when hardening the left bent portion 13b, and therefore, the following description of each component will be based on the assumption that the right bent portion 13a is hardened.

[0028] <Jigs and cylinders> 2, the workpiece 1 is placed in the quenching apparatus 2 with the top plate 11 facing vertically upward and the right flange 14a and left flange 14b facing vertically downward. The first top plate jig 31, the second top plate jig 32, the first side wall jig 33, the second side wall jig 34, and the third side wall jig 35 are members for fixing the workpiece 1 to the quenching apparatus 2. The first top plate jig 31, the second top plate jig 32, the first side wall jig 33, the second side wall jig 34, and the third side wall jig 35 are made of metal such as chromium copper or stainless steel. In this embodiment, these jigs 31 to 35 are all made of chromium copper.

[0029] The first top plate jig 31 and the second top plate jig 32 are both rectangular pillar-shaped. The cross-sectional shape perpendicular to the axial direction of each of the first top plate jig 31 and the second top plate jig 32 is approximately square. The first top plate jig 31 and the second top plate jig 32 are arranged on either side of the top plate portion 11 of the workpiece 1 placed in the hardening apparatus 2. Specifically, as shown in FIGS. 2, 4A, and 4B, the first top plate jig 31 is arranged so as to face the inner surface of the top plate portion 11, with its axial direction parallel to the inner surface of the top plate portion 11. The second top plate jig 32 is arranged so as to face the outer surface of the top plate portion 12, with its axial direction parallel to the outer surface of the top plate portion 12.

[0030] As shown in FIG. 2, a plurality of (three in this embodiment) top plate cylinders 36 are arranged on the side of the second top plate jig 32 opposite the top plate portion 11 side. The plurality of top plate cylinders 36 are configured to contact the surface of the second top plate jig 32. As an example, the plurality of top plate cylinders 36 are arranged at equal intervals. The second top plate jig 32 is configured to be displaceable toward the top plate portion 11 side by extending the rods of each of the plurality of top plate cylinders 36. When the second top plate jig 32 is displaced toward the top plate portion 11 side, the top plate portion 11 is clamped between the first top plate jig 31 and the second top plate jig 32. In other words, the first top plate jig 31 and the second top plate jig 32 are configured to clamp the top plate portion 11.

[0031] The first side wall jig 33, the second side wall jig 34, and the third side wall jig 35 are all prismatic. The cross-sectional shape perpendicular to the axial direction of each of the first side wall jig 33 and the second side wall jig 34 is rectangular. The cross-sectional shape perpendicular to the axial direction of the third side wall jig 35 is triangular.

[0032] As shown in FIGS. 2, 4A, and 4B, the third sidewall jig 35 is disposed at a right corner 15a formed by the right sidewall 12a and the right flange 14 of the workpiece 1 disposed in the hardening apparatus 2. Specifically, the third sidewall jig 35 is disposed so as to face the outer surfaces of the right sidewall 12a and the right flange 14a, with its axial direction parallel to the outer surfaces of the right sidewall 12a and the right flange 14a. The first sidewall jig 33 is disposed on the opposite side of the third sidewall jig 35 across the right sidewall 12a of the workpiece 1 disposed in the hardening apparatus 2. Specifically, the first sidewall jig 33 is disposed so as to face the inner surface of the right sidewall 12a, with its axial direction parallel to the inner surface of the right sidewall 12a. The second side wall jig 34 is disposed on the opposite side to the third side wall jig 35 across the right flange portion 14a of the workpiece 1 placed in the hardening device 2. Specifically, the second side wall jig 34 is disposed so as to face the inner surface of the right flange portion 14a, with its axial direction oriented parallel to the inner surface of the right flange portion 14a.

[0033] A plurality of sidewall cylinders 37 (three in this embodiment) are arranged on the side opposite the right corner 15a of the third sidewall jig 35. The plurality of sidewall cylinders 37 are configured to contact the surface of the third sidewall jig 35. The plurality of sidewall cylinders 37 are arranged at equal intervals, for example. The third sidewall jig 35 is configured to be displaceable toward the right corner 15a when the rods of the plurality of sidewall cylinders 37 are extended. When the third sidewall jig 35 is displaced toward the right corner 15a, the right sidewall 12a is clamped between the first sidewall jig 33 and the third sidewall jig 35. In other words, the first sidewall jig 33 and the third sidewall jig 35 are configured to clamp the right sidewall 12a. Furthermore, as the third side wall jig 35 is displaced toward the right corner 15a, the right flange portion 14a is clamped between the second side wall jig 34 and the third side wall jig 35. In other words, the second side wall jig 34 and the third side wall jig 35 are configured to clamp the right flange portion 14a.

[0034] In particular, in this embodiment, the third side wall jig 35 is configured to press the right side wall portion 12a in a direction in which the right side wall portion 12a approaches the top plate portion 11. In other words, the third side wall jig 35 is configured to press the right side wall portion 12a in a direction in which the angle θa formed between the top plate portion 11 and the right side wall portion 12a becomes smaller. The first side wall jig 33 and the third side wall jig 35 are configured to clamp the right side wall portion 12a in a state in which the right side wall portion 12a is pressed in a direction in which it approaches the top plate portion 11.

[0035] <Laser head> The laser head 21 is a part for irradiating the workpiece 1 with laser light. When the laser head 21 irradiates the workpiece 1 with laser light, the workpiece 1 is heated.

[0036] As shown in FIG. 2, the laser head 21 is disposed so as to face the right bent portion 13a of the workpiece 1 fixed to the hardening device 2. Specifically, the laser head 21 is disposed so as to face the outer surface of the right bent portion 13a. A predetermined distance is provided between the laser head 21 and the right bent portion 13a. The laser head 21 is configured to be movable along the ridge line Ra of the right bent portion 13a. Hereinafter, the direction in which the laser head 21 moves while irradiating the right bent portion 13a with laser light will be referred to as the traveling direction Y.

[0037] <Water-cooled nozzle> 6A is a part for spraying water onto the workpiece 1 that has been heated by irradiation with laser light. The workpiece 1 is rapidly cooled by the spraying of water from the water-cooling nozzle .

[0038] As shown in FIG. 6B, the water-cooled nozzle 23 is disposed so as to face the right bent portion 13a of the workpiece 1 fixed to the quenching device 2. Specifically, the water-cooled nozzle 23 is disposed so as to face the outer surface of the right bent portion 13a. A predetermined distance is provided between the water-cooled nozzle 23 and the right bent portion 13a. As shown in FIG. 6A, the water-cooled nozzle 23 is disposed behind the laser head 21 in the traveling direction Y. The water-cooled nozzle 23 is configured to be movable along the ridge line Ra of the right bent portion 13a. The water-cooled nozzle 23 is configured to be movable following the laser head 21. As an example, the speed at which the laser head 21 moves and the speed at which the water-cooled nozzle 23 moves are the same.

[0039] The water-cooled nozzle 23 is configured to inject water using a pump (not shown). The water-cooled nozzle 23 is configured to be movable following the irradiation of the laser beam, and therefore can inject water onto the right bending portion 13a following the irradiation of the laser beam by the laser head 21. Therefore, the water-cooled nozzle 23 can inject water onto the portion of the outer surface of the right bending portion 13a that is in a high temperature state and has been heated by the irradiation of the laser beam.

[0040] <Cover> The cover 22 is a member for preventing water vapor generated when the water sprayed from the water-cooled nozzle 23 is heated by the right bent portion 13a, which has a high temperature, from entering the laser beam irradiation area. The laser beam irradiation area is the area where the laser beam is currently being irradiated, and the laser beam irradiation area moves as the laser head 21 moves in the traveling direction Y. The laser beam irradiation area can also be referred to as the optical path of the laser beam.

[0041] The cover 22 is made of a material that is impermeable to water and water vapor. As shown in FIG. 2, the cover 22 is a housing that forms an internal space. In this embodiment, the cover 22 is a cylindrical shape with a closed bottom and one opening in the axial direction that is closed. The cover 22 is arranged so that its axial direction is generally along the vertical direction. The cover 22 has an upper opening in the vertical direction that is closed. In other words, the cover 22 has a ceiling wall and side walls, but does not have a bottom wall. The outer shape of a cross section of the cover 22 perpendicular to the axial direction is, for example, a quadrangle. As shown in FIG. 6A, an opening for inserting the suction nozzle 24 is formed in the side wall of the cover 22. In this embodiment, the opening is formed in a rear portion of the side wall of the cover 22 in the traveling direction Y.

[0042] The cover 22 is arranged to separate the laser light irradiation area from the water spraying area. Specifically, the cover 22 is arranged to cover the water-cooled nozzle 23 from the side opposite to the workpiece 1 side, but not to cover the laser head 21. In other words, the cover 22 is configured to cover the water spraying area from the water-cooled nozzle 23, but not to cover the laser light irradiation area from the laser head 21. The water spraying area is the area where water is currently being sprayed, and as the water-cooled nozzle 23 moves in the traveling direction Y, the water spraying area also moves.

[0043] The cover 22 is configured to be movable along the ridge line Ra of the right bent portion 13a integrally with the water-cooled nozzle 23. In other words, the cover 22 is configured to be movable along the ridge line Ra of the right bent portion 13a at the same speed as the water-cooled nozzle 23.

[0044] <Suction nozzle> The suction nozzle 24 is configured to suck gas. The tip of the suction nozzle 24 is arranged on the water ejection region side of the laser light irradiation region and the water ejection region. That is, the suction nozzle 24 is configured to suck gas on the water ejection region side. In this embodiment, the suction nozzle 24 is inserted into the cover 22 through an opening formed in the side wall of the cover 22. The tip of the suction nozzle 24 is arranged in the internal space of the cover 22. That is, the suction nozzle 24 is configured to suck gas within the cover 22. In the internal space of the cover 22, the tip of the suction nozzle 24 is arranged rearward of the water-cooled nozzle 23 in the traveling direction Y. Therefore, the suction nozzle 24 is configured to suck gas rearward of the water-cooled nozzle 23 in the traveling direction Y. The gas sucked by the suction nozzle 24 is discharged to the outside of the cover 22. Here, the outside of the cover 22 refers to a space sufficiently separated from the laser light irradiation region or a closed space that does not include the laser light irradiation region. That is, the gas sucked by the suction nozzle 24 does not enter the area irradiated with the laser light.

[0045] The suction nozzle 24 is configured to be movable along the ridge line Ra of the right bent portion 13a integrally with the cover 22. That is, the cover 22, the water-cooled nozzle 23, and the suction nozzle 24 are movable integrally in the traveling direction Y following the laser head 21.

[0046] [3. Quenching method] Next, a method for hardening the workpiece 1 will be described with reference to Figures 3A to 8B. In Figures 5A to 7B, the illustration of the plurality of top plate cylinders 36 and the plurality of side wall cylinders 37 is omitted. The method for hardening the workpiece 1 uses the above-mentioned hardening device 2. The method for hardening the workpiece 1 includes at least a placement step and a hardening step.

[0047] As described above, both the right bent portion 13a and the left bent portion 13b of the workpiece 1 are hardened. The same method is used when hardening the right bent portion 13a and when hardening the left bent portion 13b, so the following describes each step assuming that the right bent portion 13a is hardened.

[0048] <Placement process> The placement process is a process of placing the workpiece 1 in the hardening apparatus 2 and fixing the workpiece 1. As shown in FIGS. 3A and 3B , a first top plate jig 31, a first side wall jig 33, and a second side wall jig 34 are placed in the hardening apparatus 2. The first top plate jig 31, the first side wall jig 33, and the second side wall jig 34 are placed so that their axial directions are parallel. The first side wall jig 33 and the second side wall jig 34 are placed so that they form an angle corresponding to the right corner 15a of the workpiece 1. The first top plate jig 31 is placed so that its top surface is located vertically above the top surface of the second side wall jig 34 by a height corresponding to the height from the right flange portion 14a to the top plate portion 11 of the workpiece 1.

[0049] In the placement step, first, the workpiece 1 is placed on the first top plate jig 31, first side wall jig 33, and second side wall jig 34 of the hardening device 2, with the top plate 11 facing vertically upward and the right flange 14a and left flange 14b facing vertically downward. When the workpiece 1 is placed in the hardening device 2, the inner surface of the top plate 11 comes into contact with the vertically upper surface of the first top plate jig 31. Also, the vertically upper surface of the second side wall jig 34 comes into contact with the inner surface of the right flange 14a. As a result, the surface of the first side wall jig 33 on the right side wall 12a side faces the inner surface of the right side wall 12a.

[0050] Next, as shown in FIGS. 4A and 4B , the second top plate jig 32 is placed on the outer surface of the top plate portion 11 with its axial direction parallel to the axial direction of the first top plate jig 31. The second top plate jig 32 is placed so that the first top plate jig 31 and the second top plate jig 32 overlap with the top plate portion 11 in a plan view. Next, multiple top plate cylinders 36 are placed on the side of the second top plate jig 32 opposite the top plate portion 11 side. As the rods of each of the multiple top plate cylinders 36 are extended, the second top plate jig 32 is displaced toward the first top plate jig 31 side. As a result, the top plate portion 11 is clamped between the first top plate jig 31 and the second top plate jig 32. Once the top plate portion 11 is clamped between the first top plate jig 31 and the second top plate jig 32, the workpiece 1 is fixed to the hardening apparatus 2.

[0051] Next, the third sidewall jig 35 is placed at the right corner 15a with its axial direction parallel to the outer surface of the right sidewall 12a and the outer surface of the right flange 14a. Next, multiple sidewall cylinders 37 are placed on the side of the third sidewall jig 35 opposite the right corner 15a. As the rods of the multiple sidewall cylinders 37 are extended, the third sidewall jig 35 is displaced toward the first sidewall jig 33. The third sidewall jig 35 then presses the right sidewall 12a in a direction that moves the right sidewall 12a closer to the top plate 11. In other words, the third sidewall jig 35 presses the right sidewall 12a in a direction that reduces the angle θa formed between the top plate 11 and the right sidewall 12a. The third sidewall jig 35, together with the first sidewall jig 33, clamps the right sidewall 12a. In this way, with the right side wall portion 12a pressed in a direction approaching the top plate portion 11, the right side wall portion 12a is clamped between the first side wall jig 33 and the third side wall jig 35.

[0052] When the right bent portion 13a is hardened, the heating and rapid cooling of the right bent portion 13a may cause deformation (so-called thermal distortion) such that the angle θa between the top plate portion 11 and the right side wall portion 12a increases. Therefore, in the arrangement step of this embodiment, as described above, the third side wall jig 35 presses the right side wall portion 12a in the direction opposite to the deformation expected due to hardening. Pressing the right side wall portion 12a in this manner is also referred to as applying a reverse strain to the right side wall portion 12a.

[0053] When the placement step is completed, the workpiece 1 is placed and fixed in the hardening device 2. In this embodiment, the workpiece 1 is fixed to the hardening device 2 with reverse strain applied to the right side wall portion 12a.

[0054] <Quenching process> The hardening process is a process of hardening the right bent portion 13a of the workpiece 1. The hardening process is performed following the placement process. In this embodiment, in the placement process, the workpiece 1 is fixed to the hardening device 2 with reverse strain applied to the right side wall portion 12a, and therefore, in the hardening process, hardening is performed on the workpiece 1 in this state with reverse strain applied.

[0055] First, as shown in FIGS. 5A and 5B , the laser head 21 is disposed so as to face the hardening start position on the outer surface of the right bent portion 13a. In this embodiment, the hardening start position is set at one end of the right bent portion 13a in the direction of the ridge line Ra. The water-cooled nozzle 23 is disposed above the workpiece 1 (i.e., on the same side as the laser head 21 with respect to the right bent portion 13a) and behind the laser head 21 in the traveling direction Y. The suction nozzle 24 is disposed behind the water-cooled nozzle 23 in the traveling direction Y. In other words, the laser head 21, the water-cooled nozzle 23, and the suction nozzle 24 are disposed in this order from the front side in the traveling direction Y. The cover 22 is disposed so as to separate the laser light irradiation area from the water spray area. In this embodiment, the cover 22 is disposed so as to cover the tips of the water-cooled nozzle 23 and the suction nozzle 24 from above in the vertical direction.

[0056] The laser head 21, cover 22, water-cooled nozzle 23, and suction nozzle 24 all start moving at the same speed in the traveling direction Y. That is, they all start moving integrally in the traveling direction Y. The laser head 21 starts irradiating laser light as it starts moving. The water-cooled nozzle 23 starts spraying water as it starts moving. The suction nozzle 24 starts suctioning gas from within the cover 22 as it starts moving. The water-cooled nozzle 23 sprays water while gas is being sucked in by the suction nozzle 24 on the side of the water spraying area, of the laser light irradiation area and the water spraying area separated by the cover 22.

[0057] 6A and 6B, the laser head 21 irradiates the outer surface of the right bent portion 13a with laser light while moving in the traveling direction Y. The intensity of the laser light and the moving speed of the laser head are set to an intensity and moving speed that can heat the right bent portion 13a to a temperature at which austenitization begins or higher. In this embodiment, the intensity of the laser light and the moving speed of the laser head are set so that the temperature of the right bent portion 13a is heated to 900°C or higher.

[0058] The water-cooled nozzle 23 moves in the traveling direction Y following the laser head 21, while injecting water onto the outer surface of the right bent portion 13a. The amount of water injected is set to an amount that can cool the right bent portion 13a to a temperature below which the right bent portion 13a undergoes martensitic transformation at the moving speed of the laser head 21. In this embodiment, the amount of water injected is set so that the temperature of the right bent portion 13a is rapidly cooled to 200°C or below.

[0059] The cover 22 moves in the traveling direction Y at the same speed as the water-cooled nozzle 23 and the laser head 21 while covering the tips of the water-cooled nozzle 23 and the suction nozzle 24 from above in the vertical direction. Therefore, the water-cooled nozzle 23 sprays water while the cover 22 is positioned to separate the laser light irradiation area from the water spray area. In this embodiment, the water-cooled nozzle 23 sprays water while the water spray area is covered by the cover 22 and the laser light irradiation area is not covered.

[0060] Because the right bent portion 13a is heated to a high temperature by the irradiation of the laser light, the water sprayed onto the right bent portion 13a evaporates into water vapor. The suction nozzle 24 sucks in this water vapor while moving in the traveling direction Y. In addition to water vapor, the suction nozzle 24 can also suck in the air inside the cover 22, and evaporated rust-preventive oil and plating on the surface of the workpiece 1. In other words, the suction nozzle 24 sucks in substances that could disturb the laser light. The sucked-in water vapor and other substances are discharged to the outside of the cover 22 via the suction nozzle 24.

[0061] 7A and 7B, the laser head 21, cover 22, water-cooled nozzle 23, and suction nozzle 24, while performing their respective processes, move along the traveling direction Y until the water-cooled nozzle 23 reaches the end of the right bent portion 13a in the direction of the ridge line Ra on the opposite side from the hardening start position. In this way, the right bent portion 13a is heated by irradiating it with laser light and cooled by spraying water over the entire length of the right bent portion 13a in the direction of the ridge line Ra, and the hardening process is completed.

[0062] Finally, as shown in FIGS. 8A and 8B, the workpiece 1 is removed from the hardening device 2 by reversing the procedure of the above-described placement process.

[0063] [4. Effects] According to the embodiment described above in detail, the following effects can be obtained. (4a) In this embodiment, the workpiece 1 is cooled by spraying water onto it following the heating caused by irradiation of the laser light onto the workpiece 1. The spraying of water is performed in a state where the cover 22 is arranged to separate the laser light irradiation area from the water spraying area. Specifically, the spraying of water is performed in a state where the cover 22 is arranged to cover the water spraying area but not cover the laser light irradiation area.

[0064] With this configuration, when hardening the workpiece 1, even if the sprayed water is heated by the high-temperature right bent portion 13a and water vapor is generated, the water vapor can be prevented from entering the laser light irradiation area because the water spray area is covered by the cover 22. This makes it possible to prevent the laser light from being scattered by water vapor, making it easier to perform uniform hardening over the entire length of the right bent portion 13a.

[0065] (4b) In this embodiment, water is injected while gas is being sucked into the water injection area, which is separated by the cover 22 from the laser beam irradiation area. Specifically, water is injected while gas is being sucked into the cover 22. With this configuration, when hardening the workpiece 1, even if the injected water is heated by the high-temperature right bent portion 13a and water vapor is generated, the water vapor can be prevented from leaking out of the cover 22 and entering the laser beam irradiation area. Therefore, scattering of the laser beam by water vapor can be further suppressed compared to when water is injected without sucking gas into the cover 22. As a result, it is possible to more easily perform hardening more uniformly along the entire length of the right bent portion 13a.

[0066] (4c) In this embodiment, the irradiation of the laser light and the injection of water are performed in a state where the top plate portion 11 is fixed and the right side wall portion 12a is pressed in a direction toward the top plate portion 11. This configuration makes it possible to reduce the occurrence of deformation due to hardening. Therefore, it is possible to easily maintain the design shape of the workpiece 1 before and after hardening, and it is easy to assemble the workpiece 1 in the process after hardening.

[0067] (4d) According to this embodiment, it is possible to provide a quenching device 2 that achieves the effects (4a) to (4c) above.

[0068] In this embodiment, the case where the right bent portion 13a is hardened has been described, but the same effects as those of (4a) to (4d) above can also be obtained when the left bent portion 13b is hardened.

[0069] [5. Correspondence of Wording] In this embodiment, the workpiece 1 corresponds to an example of a press-formed product.

[0070] The top plate portion 11 corresponds to an example of a first wall portion, the right side wall portion 12a and the left side wall portion 12b correspond to an example of a second wall portion, and the right bent portion 13a and the left bent portion 13b correspond to an example of a bent portion.

[0071] The laser head 21 corresponds to an example of a laser irradiation unit, the cover 22 corresponds to an example of a shielding member, the water-cooled nozzle 23 corresponds to an example of a water injection unit, and the suction nozzle 24 corresponds to an example of a gas suction unit.

[0072] The first top plate jig 31 and the second top plate jig 32 correspond to an example of two fixing portions, and the first side wall jig 33 and the third side wall jig 35 correspond to an example of two pressing portions.

[0073] 6. Other Embodiments Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

[0074] (6a) In the above embodiment, the cover 22 is a cylindrical shape with a bottom that covers the water-cooled nozzle 23 from above in the vertical direction. However, the shape of the cover 22 is not particularly limited. As an example, the cover 22 may be a hemispherical shape that covers the water-cooled nozzle 23 from above in the vertical direction.

[0075] (6b) In the above embodiment, the cover 22 is given as an example of a shielding member. The cover 22 covers the water-cooled nozzle 23 from above in the vertical direction. However, the shielding member does not necessarily have to cover the water-cooled nozzle 23 from above in the vertical direction. As shown in FIGS. 9 and 10, the shielding member may be a plate-shaped shielding plate 25. The shielding plate 25 is disposed between the laser head 21 and the water-cooled nozzle 23. In this way, the shielding plate 25 separates the laser light irradiation area from the water spray area. Even with this configuration, the same effects as those of (4a) to (4d) above can be achieved.

[0076] (6c) In the above embodiment, the number of laser heads 21 that irradiate the outer surface of the right bending portion 13a with laser light is one. However, the number of laser heads 21 that irradiate the outer surface of the right bending portion 13a with laser light is not particularly limited. As an example, the number of laser heads 21 that irradiate the outer surface of the right bending portion 13a with laser light may be two. In this case, one of the two laser heads 21 may be arranged to face the top plate portion 11, and the other may be arranged to face the right side wall portion 12a. By arranging the two laser heads 21 in this manner, laser light may be irradiated onto the right bending portion 13a. As another example, the number of laser heads 21 that irradiate the right bending portion 13a with laser light may be three or more.

[0077] (6d) In the above embodiment, the laser beam is irradiated onto the outer surfaces of the right bending portion 13a and the left bending portion 13b. However, the surfaces of the right bending portion 13a and the left bending portion 13b onto which the laser beam is irradiated are not particularly limited. As an example, the laser beam may be irradiated onto the inner surfaces of the right bending portion 13a and the left bending portion 13b.

[0078] (6e) In the above embodiment, water is sprayed onto the outer surfaces of the right bending portion 13a and the left bending portion 13b. However, the surfaces onto which water is sprayed in the right bending portion 13a and the left bending portion 13b are not particularly limited. As an example, in addition to the outer surfaces of the right bending portion 13a and the left bending portion 13b, water may also be sprayed onto the inner surfaces of the right bending portion 13a and the left bending portion 13b. By spraying water simultaneously from both the outer and inner surfaces of the right bending portion 13a and the left bending portion 13b, it is possible to improve cooling efficiency. Note that, as another example, water may be sprayed onto the inner surfaces of the right bending portion 13a and the left bending portion 13b instead of the outer surfaces of the right bending portion 13a and the left bending portion 13b.

[0079] (6f) In the above embodiment, laser light is irradiated and water is sprayed onto the right bent portion 13a and the left bent portion 13b. However, laser light may be irradiated and water may be sprayed onto portions other than the right bent portion 13a and the left bent portion 13b. As an example, laser light may be irradiated and water may be sprayed onto the outer surfaces of the right bent portion 13a and the left bent portion 13b and the peripheral areas of those outer surfaces.

[0080] (6g) In the above embodiment, the right bent portion 13a and the left bent portion 13b are each hardened. In such a case, the timing at which the right bent portion 13a and the left bent portion 13b are each hardened is not particularly limited. For example, the right bent portion 13a and the left bent portion 13b may be hardened simultaneously or separately.

[0081] (6h) In the above embodiment, the workpiece 1 has a top plate portion 11, a right side wall portion 12a, a left side wall portion 12b, a right bent portion 13a, a left bent portion 13b, a right flange portion 14a, and a left flange portion 14b. However, the shape of the workpiece 1 is not particularly limited. As an example, the workpiece 1 may not have a flange portion. Also, as an example, the workpiece 1 may have one side wall portion and one bent portion instead of multiple portions.

[0082] (6i) In the above embodiment, the relative movement between the workpiece 1 and the laser head 21, the cover 22, the water-cooled nozzle 23, and the suction nozzle 24 is achieved by moving the laser head 21, the cover 22, the water-cooled nozzle 23, and the suction nozzle 24. However, the manner of the relative movement between the workpiece 1 and the laser head 21, the cover 22, the water-cooled nozzle 23, and the suction nozzle 24 is not particularly limited. As an example, the relative movement may be achieved by moving the workpiece 1, or the relative movement may be achieved by moving both the workpiece 1 and the laser head 21, the cover 22, the water-cooled nozzle 23, and the suction nozzle 24.

[0083] (6j) In the above embodiment, a plurality of top plate cylinders 36 and a plurality of side wall cylinders 37 are used to displace the second top plate jig 32 and the third side wall jig 35. However, the manner in which these jigs are displaced is not particularly limited. As an example, at least one clamp may be used instead of or in addition to the plurality of top plate cylinders 36 and the plurality of side wall cylinders 37.

[0084] (6k) In the above embodiment, the quenching device 2 includes the suction nozzle 24. However, the quenching device 2 does not necessarily have to suck in water vapor. In other words, the quenching device 2 does not necessarily have to include the suction nozzle 24.

[0085] (61) In the above embodiment, the workpiece 1 is made of high-tensile steel material with high tensile strength. However, the type of steel material making up the workpiece is not particularly limited. As an example, the workpiece 1 may be made of steel material other than high-tensile steel.

[0086] (6m) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0087] [Technical idea disclosed in this specification] [Item 1] A method for quenching a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bent portion connecting the first wall portion and the second wall portion, comprising: heating the bent portion by irradiating the bent portion with laser light; cooling the heated bent portion by injecting water onto the bent portion following the irradiation of the laser light; Including, The water injection is performed in a state where a shielding member is disposed to separate the laser light irradiation area from the water injection area.

[0088] [Item 2] The quenching method according to item 1, The water is sprayed in a state where the shielding member is positioned so as to cover the water spray area but not the laser light irradiation area.

[0089] [Item 3] The quenching method according to item 1 or 2, The water injection is performed in a state where gas is sucked in on the water injection area side of the laser light irradiation area and the water injection area separated by the shielding member.

[0090] [Item 4] The quenching method according to any one of items 1 to 3, The quenching method, wherein the irradiation of the laser light and the injection of the water are performed in a state where the first wall portion is fixed and the second wall portion is pressed in a direction approaching the first wall portion.

[0091] [Item 5] The quenching method according to any one of items 1 to 4, The press-formed product is made of high-tensile steel.

[0092] [Item 6] A quenching device for a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bent portion connecting the first wall portion and the second wall portion, a laser irradiation unit configured to irradiate the bent portion with laser light; a water injection unit configured to inject water onto the bent portion in response to the irradiation of the laser light; a shielding member disposed to separate the laser light irradiation area from the water ejection area; A quenching device comprising:

[0093] [Item 7] Item 6. The quenching device according to item 6, The quenching device, wherein the shielding member is positioned so as to cover the water injection area and not to cover the laser light irradiation area.

[0094] [Item 8] The quenching device according to item 6 or 7, a gas suction unit configured to suck gas on the water injection region side of the laser light irradiation region and the water injection region separated by the shielding member.

[0095] [Item 9] The quenching device according to any one of items 6 to 8, two fixing portions arranged on opposite sides of the first wall portion and configured to sandwich the first wall portion; two pressing portions arranged on either side of the second wall portion and configured to sandwich the second wall portion; Further provided with The two pressing portions are configured to sandwich the second wall portion while pressing the second wall portion in a direction toward the first wall portion.

[0096] [Item 10] The quenching device according to any one of items 6 to 9, The press-formed product is made of high-tensile steel. [Explanation of symbols]

[0097] 1...workpiece, 2...hardening device, 11...top plate portion, 12a...right side wall portion, 12b...left side wall portion, 13a...right bending portion, 13b...left bending portion, 21...laser head, 22...cover, 23...water cooling nozzle, 24...suction nozzle, 25...shielding plate, 31...first top plate jig, 32...second top plate jig, 33...first side wall jig, 34...second side wall jig, 35...third side wall jig, X...extension direction, Y...traveling direction.

Claims

1. A method for quenching a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bent portion connecting the first wall portion and the second wall portion, comprising: heating the bent portion by irradiating the bent portion with laser light; cooling the heated bent portion by injecting water onto the bent portion following the irradiation of the laser light; Including, the irradiation of the laser light is performed in a state in which the first wall portion is fixed and the second wall portion is pressed in a direction approaching the first wall portion, The water is injected in a state in which the first wall portion is fixed, the second wall portion is pressed in a direction approaching the first wall portion, and a shielding member is positioned to separate the laser light irradiation area from the water injection area.

2. The quenching method according to claim 1, The water is sprayed in a state where the shielding member is positioned so as to cover the water spray area but not the laser light irradiation area.

3. The quenching method according to claim 1 or 2, The water injection is performed in a state where gas is sucked in on the water injection area side of the laser light irradiation area and the water injection area separated by the shielding member.

4. The quenching method according to claim 1 or 2, The press-formed product is made of high-tensile steel.

5. A quenching apparatus for a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bent portion connecting the first wall portion and the second wall portion, two fixing portions arranged on opposite sides of the first wall portion and configured to sandwich the first wall portion; two pressing portions arranged on both sides of the second wall portion and configured to sandwich the second wall portion in a state in which the second wall portion is pressed in a direction approaching the first wall portion; a laser irradiation unit configured to irradiate the bent portion with laser light; a water injection unit configured to inject water onto the bent portion in response to the irradiation of the laser light; a shielding member disposed to separate the laser light irradiation area from the water ejection area; A quenching device comprising:

6. 6. The quenching device according to claim 5, The quenching device, wherein the shielding member is positioned so as to cover the water injection area and not to cover the laser light irradiation area.

7. The quenching device according to claim 5 or 6, a gas suction unit configured to suck gas on the water injection region side of the laser light irradiation region and the water injection region separated by the shielding member.

8. The quenching device according to claim 5 or 6, The press-formed product is made of high-tensile steel.

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