Quenching method and quenching apparatus

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 quenching press-formed products.

Background Art

[0002] For example, Patent Document 1 discloses a quenching method for a steel plate as a workpiece. In this method, a heat treatment by irradiating the workpiece with a laser beam and a cooling treatment by spraying water onto the heated workpiece are continuously performed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique described in Patent Document 1, the sprayed cooling water may be heated by the heated workpiece, resulting in the generation of water vapor. In such a case, the water vapor may enter the laser beam irradiation area and scatter the laser beam. When the water vapor scatters the laser beam, the quenching may become non-uniform.

[0005] One aspect of the present disclosure provides a technique for suppressing the scattering of a laser beam caused by cooling water when quenching a press-formed product.

Means for Solving the Problems

[0006] One aspect of the present disclosure is a quenching method for a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bending portion connecting the first wall portion and the second wall portion. The quenching method for the press-formed product includes heating the bending portion by irradiating the bending portion with laser light, and cooling the heated bending portion by injecting water into the bending portion following the irradiation of the laser light. The water injection is performed in a state where a shielding member is disposed so as to separate the laser light irradiation region and the water injection region.

[0007] According to such a configuration, when quenching the press-formed product, scattering of the laser light caused by the cooling water can be suppressed.

[0008] In one aspect of the present disclosure, the water injection may be performed in a state where a shielding member covers the water injection region and does not cover the laser light irradiation region. According to such a configuration, when quenching the press-formed product, scattering of the laser light caused by the cooling water can be further suppressed.

[0009] In one aspect of the present disclosure, the water injection may be performed in a state where gas is being sucked on the side of the water injection region among the laser light irradiation region and the water injection region separated by a shielding member. According to such a configuration, when quenching the press-formed product, scattering of the laser light caused by the cooling water can be further suppressed.

[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 where the first wall portion is fixed and the second wall portion is pressed in a direction approaching the first wall portion. According to such a configuration, it is possible to make it difficult to cause deformation accompanying quenching.

[0011] One aspect of the present disclosure is a quenching apparatus for a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bending portion connecting the first wall portion and the second wall portion, the apparatus including a laser irradiation unit, a water injection unit, and a cover. The laser irradiation unit is configured to irradiate the bending portion with laser light. The water injection unit is configured to inject water onto the bending portion following the irradiation of the laser light. A shielding member is disposed so as to separate the laser light irradiation region and the water injection region.

[0012] According to such a configuration, when quenching the press-formed product, scattering of the laser light caused by the cooling water can be suppressed.

[0013] In one aspect of the present disclosure, the shielding member may be disposed so as to cover the water injection region and not cover the laser light irradiation region. According to such a configuration, when quenching the press-formed product, scattering of the laser light caused by the cooling water can be further suppressed.

[0014] In one aspect of the present disclosure, among the laser light irradiation region and the water injection region separated by the shielding member, a gas suction unit configured to suction gas may be further provided on the side of the water injection region. According to such a configuration, when quenching the press-formed product, water is injected while gas is being suctioned by the gas suction unit, thereby further suppressing scattering of the laser light caused by the cooling water.

[0015] In one aspect of the present disclosure, two fixing portions and two pressing portions may be further provided. The fixing portions are disposed on both sides sandwiching the first wall portion and are configured to sandwich the first wall portion. The pressing portions are disposed on both sides sandwiching the second wall portion and are configured to sandwich the second wall portion. The two pressing portions may be configured to sandwich the second wall portion in a state where the second wall portion is pressed in a direction approaching the first wall portion. According to such a configuration, deformation associated with quenching can be made less likely to occur.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

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[0017] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. Configuration of Workpiece] FIG. 1 shows a workpiece 1 to be quenched in the quenching method and quenching apparatus of the present disclosure. The workpiece 1 is, as an example, a component of an automobile body. Specific examples of components of an automobile body include pillars and members of an automobile. Note that the terms regarding the directions used for the workpiece 1 are used to assist the reader in understanding the present disclosure and do not limit the usage mode of the workpiece 1.

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

[0019] As shown in FIG. 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 perpendicular to the extension direction X of the workpiece 1 is constant in the extension direction X. The cross-sectional shape perpendicular to the extension direction X of the workpiece 1 is symmetric about the vertical axis.

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

[0021] The top plate portion 11 is a plate-like portion. Specifically, the top plate portion 11 is a flat plate having a rectangular shape when viewed from the front. The two long sides of the top plate portion 11 in the front view 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 flat plate-shaped in a rectangular shape when viewed from the front. In each of the right side wall portion 12a and the left side wall portion 12b, the two long sides in their front view are parallel to the extending 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 the top plate portion 11. That the right side wall portion 12a or the left side wall portion 12b intersects the top plate portion 11 means, more specifically, that the virtual plane including the right side wall portion 12a or the left side wall portion 12b intersects the virtual plane including the top plate portion 11. The angle θa formed by the right side wall portion 12a and the top plate portion 11, and the angle θb formed by the left side wall portion 12b and the top plate portion 11 are both, as an example, greater than 90 degrees. That is, the right side wall portion 12a and the left side wall portion 12b are inclined with respect to the top plate portion 11 such that the distance between the two widens as they move away from the top plate portion 11.

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

[0024] Hereinafter, among the two surfaces of the right bending portion 13a, the surface on the inner side in the radial direction is referred to as the inner surface, and the surface on the outer side in the radial direction is referred to as the outer surface. Among the two surfaces of the left bending portion 13b, the surface on the inner side in the radial direction is referred to as the inner surface, and the surface on the outer side in the radial direction is referred to as the outer surface. Among the two surfaces of the right side wall portion 12a, the surface continuous with the inner surface of the right bending portion 13a is referred to as the inner surface, and the surface continuous with the outer surface of the right bending portion 13a is referred to as the outer surface. Among the two surfaces of the left side wall portion 12b, the surface continuous with the inner surface of the left bending portion 13b is referred to as the inner surface, and the surface continuous with the outer surface of the left bending portion 13b is referred to as the outer surface. Among the two surfaces of the top plate portion 11, the surface continuous with the inner surface of each of the right bending portion 13a and the left bending portion 13b is referred to as the inner surface, and the surface continuous with the outer surface of each of the right bending portion 13a and the left bending portion 13b is referred to as the outer surface.

[0025] The right flange portion 14a and the left flange portion 14b are plate-like portions. Specifically, the right flange portion 14a and the left flange portion 14b are flat plate-like in a rectangular shape when viewed from the front. In each of the right flange portion 14a and the left flange portion 14b, the two long sides are parallel to the extending direction X. The right flange portion 14a extends outward from the end face on the side opposite to the top plate portion 11 among the two end faces extending along the extending direction X in the right side wall portion 12a. The outside mentioned here means the side opposite to the top plate portion 11 with the right side wall portion 12a interposed therebetween. In other words, the outside mentioned here is the outer surface side of the right side wall portion 12a. The left flange portion 14b extends outward from the end face on the side opposite to the top plate portion 11 among the two end faces extending along the extending direction X in the left side wall portion 12b. The outside mentioned here refers to the side opposite to the top plate portion 11 with the left side wall portion 12b interposed therebetween. In other words, the outside mentioned here is the outer surface side of the left side wall portion 12b. The right flange portion 14a and the left flange portion 14b extend in a direction away from each other from the right side wall portion 12a and the left side wall portion 12b. Each of the right flange portion 14a and the left flange portion 14b extends substantially parallel to the top plate portion 11. Hereinafter, among the two surfaces of the right flange portion 14a, the surface continuous with the inner surface of the right side wall portion 12a is referred to as the inner surface, and the surface continuous with the outer surface of the right side wall portion 12a is referred to as the outer surface. Among the two surfaces of the left flange portion 14b, the surface continuous with the inner surface of the left side wall portion 12b is referred to as the inner surface, and the surface continuous with the outer surface of the left side wall portion 12b is referred to as the outer surface.

[0026] The body of an automobile is required to have high strength, and high-strength materials are generally expensive in many cases. Therefore, as an example, by locally quenching a portion that particularly requires strength in a press-formed product, the strength of the entire press-formed product may be increased. For the workpiece 1, as an example, local quenching is performed on the right bending portion 13a and the left bending portion 13b. As an example, when local quenching is performed on the right bending portion 13a and the left bending portion 13b of the workpiece 1 whose tensile strength before quenching is 1000 MPa, the tensile strength of the entire workpiece 1 becomes 1500 MPa.

[0027] [2. Configuration of Quenching Device] The quenching device 2 shown in Fig. 2 is configured to perform quenching on the workpiece 1. Specifically, the quenching device 2 is configured to perform quenching on the right bending portion 13a and the left bending 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-cooling nozzle 23, and a suction nozzle 24. Since these configurations of the quenching device 2 are used in the same manner for both the case of performing quenching on the right bending portion 13a and the case of performing quenching on the left bending portion 13b, hereinafter, each configuration will be described assuming the case of performing quenching on the right bending portion 13a.

[0028] <Jigs and cylinders> As shown in Fig. 2, the workpiece 1 is disposed in the quenching device 2 with the top plate portion 11 side facing upward in the vertical direction and the right flange portion 14a and the left flange portion 14b sides facing downward in the vertical direction. 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 device 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 a metal such as chromium copper or stainless steel. In this embodiment, these jigs 31 to 35 are all made of chromium copper.

[0029] Both the first top plate jig 31 and the second top plate jig 32 are prismatic. 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 substantially square. The first top plate jig 31 and the second top plate jig 32 are disposed on both sides sandwiching the top plate portion 11 of the workpiece 1 disposed in the quenching device 2. Specifically, as shown in Figs. 2, 4A, and 4B, the first top plate jig 31 is disposed so that its axial direction is parallel to the inner surface of the top plate portion 11 and faces the inner surface of the top plate portion 11. The second top plate jig 32 is disposed so that its axial direction is parallel to the outer surface of the top plate portion 12 and faces 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 to 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. The plurality of top plate cylinders 36 are arranged at equal intervals as an example. The second top plate jig 32 is configured to be displaceable toward the top plate portion 11 side by extending the rods of the plurality of top plate cylinders 36 respectively. When the second top plate jig 32 is displaced toward the top plate portion 11 side, the top plate portion 11 is clamped by 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 side wall jig 35 is arranged at the right corner portion 15a which is the corner formed by the right side wall portion 12a and the right flange portion 14 in the work 1 arranged in the quenching device 2. Specifically, the third side wall jig 35 is arranged so that its axial direction is parallel to each of the outer surface of the right side wall portion 12a and the outer surface of the right flange portion 14 and faces the outer surface of the right side wall portion 12a and the outer surface of the right flange portion 14a. The first side wall jig 33 is arranged on the side opposite to the third side wall jig 35 side with the right side wall portion 12a of the work 1 arranged in the quenching device 2 interposed therebetween. Specifically, the first side wall jig 33 is arranged so that its axial direction is parallel to the inner surface of the right side wall portion 12a and faces the inner surface of the right side wall portion 12a. The second side wall jig 34 is arranged on the side opposite to the third side wall jig 35 side with the right flange portion 14a of the work 1 arranged in the quenching device 2 interposed therebetween. Specifically, the second side wall jig 34 is arranged so that its axial direction is parallel to the inner surface of the right flange portion 14a and faces the inner surface of the right flange portion 14a.

[0033] On the side opposite to the right corner portion 15a side of the third side wall jig 35, a plurality of (three in this embodiment) side wall cylinders 37 are arranged. The plurality of side wall cylinders 37 are configured to contact the surface of the third side wall jig 35. The plurality of side wall cylinders 37 are arranged at equal intervals as an example. The third side wall jig 35 is configured to be displaceable toward the right corner portion 15a side when the rods of the plurality of side wall cylinders 37 are each extended. When the third side wall jig 35 is displaced toward the right corner portion 15a side, the right side wall portion 12a is clamped by the first side wall jig 33 and the third side wall jig 35. In other words, the first side wall jig 33 and the third side wall jig 35 are configured to clamp the right side wall portion 12a. Further, when the third side wall jig 35 is displaced toward the right corner portion 15a side, the right flange portion 14a is clamped by 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] Particularly 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 while pressing the right side wall portion 12a in a direction in which the right side wall portion 12a approaches the top plate portion 11.

[0035] <Laser head> The laser head 21 is a part for irradiating the workpiece 1 with laser light. The workpiece 1 is heated by the irradiation of laser light by the laser head 21.

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

[0037] <Water cooling nozzle> The water cooling nozzle 23 shown in FIG. 6A is a part for injecting water onto the work 1 heated by the irradiation of laser light. The work 1 is rapidly cooled by the injection of water from the water cooling nozzle 23.

[0038] As shown in FIG. 6B, the water cooling nozzle 23 is arranged to face the right bending portion 13a of the work 1 fixed to the quenching device 2. Specifically, the water cooling nozzle 23 is arranged to face the outer surface of the right bending portion 13a. A predetermined interval is provided between the water cooling nozzle 23 and the right bending portion 13a. As shown in FIG. 6A, the water cooling nozzle 23 is arranged behind the laser head 21 in the traveling direction Y. The water cooling nozzle 23 is configured to be movable along the ridge line Ra of the right bending portion 13a. The water cooling 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 cooling nozzle 23 moves are the same.

[0039] The water cooling nozzle 23 is configured to inject water using a pump (not shown). Since the water cooling nozzle 23 is configured to be movable following the irradiation of laser light, it is possible to inject water onto the right bending portion 13a following the irradiation of laser light by the laser head 21. Therefore, the water cooling 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 heated by the irradiation of laser light.

[0040] <Cover> The cover 22 is a member for suppressing the intrusion of water vapor generated by heating the water sprayed from the water-cooling nozzle 23 by the right bending portion 13a at a high temperature into the laser light irradiation region. The laser light irradiation region refers to the region where the laser light is actually irradiated, and as the laser head 21 moves in the advancing direction Y, the laser light irradiation region also moves. The laser light irradiation region can also be referred to as the optical path of the laser light.

[0041] The cover 22 is made of a material that does not transmit water and water vapor. As shown in FIG. 2, the cover 22 is a housing that forms an internal space. In the present embodiment, the cover 22 has a bottomed cylindrical shape with one opening in the axial direction closed. The cover 22 is arranged such that its axial direction generally follows the vertical direction. The upper opening in the vertical direction of the cover 22 is closed. That is, the cover 22 has a ceiling wall and a side wall and does not have a bottom wall. The outer shape of the cross section perpendicular to the axial direction of the cover 22 is, for example, a quadrangular shape. As shown in FIG. 6A, an opening for inserting the suction nozzle 24 is formed in the side wall of the cover 22. In the present embodiment, the opening is formed in the portion of the side wall of the cover 22 on the rear side in the advancing direction Y.

[0042] The cover 22 is arranged so as to separate the laser light irradiation region and the water injection region. Specifically, the cover 22 is arranged to cover the water-cooling nozzle 23 from the side opposite to the workpiece 1 side, while not covering the laser head 21. That is, the cover 22 is configured to cover the water injection region by the water-cooling nozzle 23 and not to cover the laser light irradiation region by the laser head 21. The water injection region refers to the region where water injection is actually performed, and as the water-cooling nozzle 23 moves in the advancing direction Y, the water injection region also moves.

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

[0044] <Suction nozzle> The suction nozzle 24 is configured to suck gas. The tip of the suction nozzle 24 is disposed on the side of the water injection region among the laser beam irradiation region and the water injection region. That is, the suction nozzle 24 is configured to suck gas on the side of the water injection region. In the present embodiment, the suction nozzle 24 is inserted into the cover 22 from an opening formed in the side wall of the cover 22. The tip of the suction nozzle 24 is disposed in the internal space of the cover 22. That is, the suction nozzle 24 is configured to suck the gas in the cover 22. In the internal space of the cover 22, the tip of the suction nozzle 24 is disposed behind the water-cooling nozzle 23 in the traveling direction Y. For this reason, the suction nozzle 24 is configured to suck gas backward with respect to the water-cooling 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 beam irradiation region, or a closed space that does not include the laser beam irradiation region. That is, the gas sucked by the suction nozzle 24 does not enter the laser beam irradiation region.

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

[0046] [3. Quenching method] Next, a quenching method for the workpiece 1 will be described with reference to FIGS. 3A to 8B. In FIGS. 5A to 7B, illustrations of the plurality of top plate cylinders 36 and the plurality of side wall cylinders 37 are omitted. The quenching method for the workpiece 1 uses the quenching device 2 described above. The quenching method for the workpiece 1 includes at least an arrangement step and a quenching step.

[0047] Note that, as described above, quenching is performed on both the right bending portion 13a and the left bending portion 13b of the workpiece 1. Since the same method is used for both the case of performing quenching on the right bending portion 13a and the case of performing quenching on the left bending portion 13b, the following will describe each process assuming the case of performing quenching on the right bending portion 13a.

[0048] <Placement Process> The placement process is a process of placing the workpiece 1 in the quenching device 2 and fixing the workpiece 1. As shown in FIGS. 3A and 3B, in the quenching device 2, a first top plate jig 31, a first side wall jig 33, and a second side wall jig 34 are arranged. The first top plate jig 31, the first side wall jig 33, and the second side wall jig 34 are arranged such that their respective axial directions are parallel. The first side wall jig 33 and the second side wall jig 34 are arranged at an angle corresponding to the right corner portion 15a of the workpiece 1. The first top plate jig 31 is arranged such that its upper surface is positioned vertically above the upper 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 process, first, the workpiece 1 is placed on the first top plate jig 31, the first side wall jig 33, and the second side wall jig 34 in the quenching device 2 with the top plate portion 11 side facing upward in the vertical direction and the right flange portion 14a and the left flange portion 14b sides facing downward in the vertical direction. In the state where the workpiece 1 is placed in the quenching device 2, the inner surface of the top plate portion 11 contacts the upper surface of the first top plate jig 31 in the vertical direction. Also, the upper surface of the second side wall jig 34 in the vertical direction contacts the inner surface of the right flange portion 14a. As a result, the surface of the right side wall portion 12a side of the first side wall jig 33 faces the inner surface of the right side wall portion 12a.

[0050] Next, as shown in FIGS. 4A and 4B, the second top plate jig 32 is disposed on the outer surface of the top plate portion 11 in a direction in which its axial direction is parallel to the axial direction of the first top plate jig 31. In a plan view, the first top plate jig 31 and the second top plate jig 32 are disposed so as to overlap with each other with the top plate portion 11 therebetween. Subsequently, a plurality of top plate cylinders 36 are disposed on the side opposite to the top plate portion 11 side of the second top plate jig 32. By extending the rods of the plurality of top plate cylinders 36, 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 by the first top plate jig 31 and the second top plate jig 32. When the top plate portion 11 is clamped by the first top plate jig 31 and the second top plate jig 32, the workpiece 1 is fixed to the quenching device 2.

[0051] Next, the third side wall jig 35 is disposed at the right corner portion 15a in a direction in which its axial direction is parallel to each of the outer surface of the right side wall portion 12a and the outer surface of the right flange portion 14a. Subsequently, a plurality of side wall cylinders 37 are disposed on the side opposite to the right corner portion 15a side of the third side wall jig 35. By extending the rods of the plurality of side wall cylinders 37, the third side wall jig 35 is displaced toward the first side wall jig 33 side. Then, the third side wall jig 35 presses 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 presses the right side wall portion 12a in a direction in which the angle θa formed by the top plate portion 11 and the right side wall portion 12a becomes smaller. The third side wall jig 35 clamps the right side wall portion 12a together with the first side wall jig 33. In this way, in a state where the right side wall portion 12a is pressed in a direction in which it approaches the top plate portion 11, the right side wall portion 12a is in a state of being clamped by the first side wall jig 33 and the third side wall jig 35.

[0052] When quenching is performed on the right bending portion 13a, due to the heating and rapid cooling of the right bending portion 13a, the angle θa formed by the top plate portion 11 and the right side wall portion 12a may be deformed to increase (so-called thermal distortion may occur). Therefore, in the arrangement process of the present embodiment, as described above, the third side wall jig 35 presses the right side wall portion 12a in the direction opposite to the deformation assumed by quenching. Pressing the right side wall portion 12a in this way is also referred to as applying reverse strain to the right side wall portion 12a.

[0053] When the arrangement process is completed, the work 1 is placed and fixed in the quenching device 2 in a state where the work 1 is placed. In the present embodiment, the work 1 is fixed to the quenching device 2 in a state where reverse strain is applied to the right side wall portion 12a.

[0054] <Quenching process> The quenching process is a process of performing quenching on the right bending portion 13a of the work 1. The quenching process is performed following the arrangement process. In the present embodiment, in the arrangement process, since the work 1 is fixed to the quenching device 2 in a state where reverse strain is applied to the right side wall portion 12a, in the quenching process, quenching is performed on the work 1 in a state where such reverse strain is applied.

[0055] First, as shown in FIGS. 5A and 5B, the laser head 21 is arranged so as to face the quenching start position on the outer surface of the right bending portion 13a. In the present embodiment, the quenching start position is set at one end in the direction of the ridge line Ra of the right bending portion 13a. The water-cooling nozzle 23 is arranged above the work 1 (that is, on the same side as the laser head 21 with respect to the right bending portion 13a) and behind the laser head 21 in the traveling direction Y. The suction nozzle 24 is arranged behind the water-cooling nozzle 23 in the traveling direction Y. That is, the laser head 21, the water-cooling nozzle 23, and the suction nozzle 24 are arranged in this order from the front side in the traveling direction Y. The cover 22 is arranged so as to separate the laser light irradiation region and the water injection region. In the present embodiment, the cover 22 is arranged so as to cover the tips of the water-cooling nozzle 23 and the suction nozzle 24 from vertically above.

[0056] The laser head 21, the cover 22, the water-cooling nozzle 23, and the suction nozzle 24 all start moving in the traveling direction Y at the same speed. That is, they start moving in the traveling direction Y integrally. When the movement starts, the laser head 21 starts irradiating laser light. When the movement starts, the water-cooling nozzle 23 starts injecting water. When the movement starts, the suction nozzle 24 starts sucking the gas inside the cover 22. The injection of water by the water-cooling nozzle 23 is performed on the side of the water injection region in a state where the gas is being sucked by the suction nozzle 24 among the laser light irradiation region and the water injection region separated by the cover 22.

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

[0058] While moving in the traveling direction Y following the laser head 21, the water-cooling nozzle 23 injects water onto the outer surface of the right bending portion 13a. The amount of water injection is set to an injection amount that can cool the right bending portion 13a to a temperature at which martensite transformation occurs or lower at the moving speed of the laser head 21. In the present embodiment, the amount of water injection is set so that the temperature of the right bending portion 13a is rapidly cooled to 200° C. or lower.

[0059] The cover 22 moves in the traveling direction Y at the same speed as the water-cooling nozzle 23 and the laser head 21 in a state of covering the tips of the water-cooling nozzle 23 and the suction nozzle 24 from vertically above. Therefore, the injection of water by the water-cooling nozzle 23 is performed in a state where the cover 22 is arranged so as to separate the laser light irradiation region and the water injection region. In the present embodiment, the injection of water by the water-cooling nozzle 23 is performed in a state where the water injection region is covered by the cover 22 and the laser light irradiation region is not covered.

[0060] Since the right bending portion 13a is at a high temperature due to the irradiation of the laser beam, the water sprayed onto the right bending portion 13a vaporizes into water vapor. The suction nozzle 24 moves in the traveling direction Y while sucking this water vapor. The suction nozzle 24 can suck, in addition to the water vapor, the air inside the cover 22 and the evaporated substances such as the rust preventive oil and plating on the surface of the workpiece 1. That is, the suction nozzle 24 sucks substances that can cause disturbances to the laser beam. The sucked water vapor and the like are discharged to the outside of the cover 22 through the suction nozzle 24.

[0061] As shown in FIGS. 7A and 7B, while the laser head 21, the cover 22, the water-cooling nozzle 23, and the suction nozzle 24 perform their respective processes, they move along the traveling direction Y until the water-cooling nozzle 23 reaches the end on the opposite side of the quenching start position in the ridge line Ra direction of the right bending portion 13a. In this way, when heating by irradiation of the laser beam and cooling by spraying of water are performed on the right bending portion 13a over the entire length in the ridge line Ra direction of the right bending portion 13a, the quenching process is completed.

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

[0063] [4. Effects] According to the embodiment described in detail above, the following effects can be obtained. (4a) In this embodiment, following the heating of the workpiece 1 by irradiation of the laser beam, cooling of the workpiece 1 by spraying of water is performed. The spraying of water is performed in a state where the cover 22 is arranged so that the laser beam irradiation region and the water spraying region are separated. Specifically, the spraying of water is performed in a state where the cover 22 covers the water spraying region and does not cover the laser beam irradiation region.

[0064] According to such a configuration, when quenching the workpiece 1, even if the sprayed water is heated by the right bending portion 13a that is at a high temperature to generate water vapor, since the water injection area is covered by the cover 22, it is possible to suppress the intrusion of the water vapor into the laser beam irradiation area. Therefore, it is possible to suppress the scattering of the laser beam by the water vapor, and it becomes easier to perform quenching uniformly over the entire length of the right bending portion 13a.

[0065] (4b) In the present embodiment, the water injection is performed in a state where gas is being sucked on the water injection area side among the laser beam irradiation area and the water injection area separated by the cover 22. Specifically, the water injection is performed in a state where the gas inside the cover 22 is being sucked. According to such a configuration, when quenching the workpiece 1, even if the sprayed water is heated by the right bending portion 13a that is at a high temperature to generate water vapor, it is possible to suppress the water vapor from leaking out of the cover 22 and entering the laser beam irradiation area. Therefore, compared to the case where water injection is performed with the gas inside the cover 22 not being sucked, it is possible to further suppress the scattering of the laser beam by the water vapor. As a result, it becomes easier to perform quenching more uniformly over the entire length of the right bending portion 13a.

[0066] (4c) In the present embodiment, the irradiation of the laser beam 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 approaching the top plate portion 11. According to such a configuration, it is possible to make it difficult to generate deformation accompanying quenching. Therefore, it is possible to easily maintain the designed shape of the workpiece 1 before and after quenching, and it is possible to easily assemble the workpiece 1 in the post-quenching process.

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

[0068] In the present embodiment, the case where quenching is performed on the right bending portion 13a has been described. However, even when quenching is performed on the left bending portion 13b, effects similar to those of the above (4a) to (4d) can be obtained.

[0069] [5. Corresponding relationships of terms] In the present embodiment, the workpiece 1 corresponds to an example of a press-formed product.

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

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

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

[0073] [6. Other embodiments] As described above, the embodiments of the present disclosure have been described. Needless to say, the present disclosure can take various forms without being limited to the above embodiments.

[0074] (6a) In the above embodiment, the cover 22 is a bottomed cylindrical shape that covers the water-cooling 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-cooling nozzle 23 from above in the vertical direction.

[0075] (6b) In the above embodiment, the cover 22 was exemplified as an example of the shielding member. The cover 22 covers the water-cooling nozzle 23 from above in the vertical direction. However, the shielding member does not necessarily have to cover the water-cooling 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-cooling nozzle 23. In this way, the shielding plate 25 separates the laser light irradiation region and the water injection region. Even in such a configuration, the same effects as those in the above (4a) to (4d) are achieved.

[0076] (6c) In the above embodiment, the number of laser heads 21 that irradiate laser light on the outer surface of the right bending portion 13a is one. However, the number of laser heads 21 that irradiate laser light on the outer surface of the right bending portion 13a is not particularly limited. As an example, the number of laser heads 21 that irradiate laser light on the outer surface of the right bending portion 13a may be two. In this case, of the two laser heads 21, one 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 way, the right bending portion 13a may be irradiated with laser light. Further, as another example, the number of laser heads 21 that irradiate laser light on the right bending portion 13a may be three or more.

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

[0078] (6e) In the above-described embodiment, water is sprayed onto the outer surfaces of the right bending portion 13a and the left bending portion 13b, respectively. However, the surfaces on 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, respectively. For each of the right bending portion 13a and the left bending portion 13b, by spraying water simultaneously from both the outer surface and the inner surface, the cooling efficiency can be improved. Note that, as another example, instead of the outer surfaces of the right bending portion 13a and the left bending portion 13b, water may be sprayed onto the inner surfaces of the right bending portion 13a and the left bending portion 13b, respectively.

[0079] (6f) In the above-described embodiment, the right bending portion 13a and the left bending portion 13b are irradiated with laser light and water is sprayed thereon. However, laser light irradiation and water spraying may also be performed on portions other than the right bending portion 13a and the left bending portion 13b. As an example, laser light irradiation and water spraying may be performed on the outer surfaces of the right bending portion 13a and the left bending portion 13b and the peripheral portions of those outer surfaces.

[0080] (6g) In the above-described embodiment, quenching is performed on each of the right bending portion 13a and the left bending portion 13b. In such a case, the timing at which quenching is performed on each of the right bending portion 13a and the left bending portion 13b is not particularly limited. As an example, quenching of the right bending portion 13a and the left bending portion 13b may be performed simultaneously, or separately.

[0081] (6h) In the above-described embodiment, the workpiece 1 has a top plate portion 11, a right side wall portion 12a, a left side wall portion 12b, a right bending portion 13a, a left bending 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 bending portion each instead of a plurality.

[0082] (6i) In the above embodiment, the relative movement between the work 1 and the laser head 21, the cover 22, the water-cooling nozzle 23, and the suction nozzle 24 is realized by moving the laser head 21, the cover 22, the water-cooling nozzle 23, and the suction nozzle 24. However, the mode of relative movement between the work 1 and the laser head 21, the cover 22, the water-cooling nozzle 23, and the suction nozzle 24 is not particularly limited. As an example, the relative movement may be realized by moving the work 1, or may be realized by moving both the work 1 and the laser head 21, the cover 22, the water-cooling 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 mode of displacing these jigs 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, in the quenching device 2, water vapor does not necessarily have to be sucked. In other words, the quenching device 2 may not include the suction nozzle 24.

[0085] (6l) In the above embodiment, the work 1 is made of high-tensile steel with high tensile strength. However, the type of steel material constituting the work is not particularly limited. As an example, the work 1 may be made of a steel material other than high-tensile steel.

[0086] (6m) The functions of one component in the above embodiment may be distributed among a plurality of components, or the functions of a plurality of components may be integrated into one component. Also, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above embodiment may be added to, replaced with, etc., the configuration of other above embodiments.

[0087] [Technical idea disclosed in this specification] [Item 1] A quenching method for a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bending portion connecting the first wall portion and the second wall portion, comprising: heating the bending portion by irradiating the bending portion with a laser beam; cooling the heated bending portion by spraying water onto the bending portion following the irradiation of the laser beam; and the quenching method, wherein the water spraying is performed in a state where a shielding member is disposed so as to separate the laser beam irradiation region and the water spraying region.

[0088] [Item 2] The quenching method according to Item 1, wherein the water spraying is performed in a state where the shielding member covers the water spraying region and does not cover the laser beam irradiation region.

[0089] [Item 3] The quenching method according to Item 1 or Item 2, wherein the water spraying is performed in a state where gas is being sucked on the side of the water spraying region among the laser beam irradiation region and the water spraying region separated by the shielding member.

[0090] [Item 4] The quenching method according to any one of Items 1 to 3, wherein the laser beam irradiation and the water spraying 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, wherein 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 bending portion connecting the first wall portion and the second wall portion, a laser irradiation unit configured to irradiate the bending portion with laser light, a water injection unit configured to inject water into the bending portion following the irradiation of the laser light, a shielding member disposed so as to separate the laser light irradiation region and the water injection region, and a quenching device comprising the same.

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

[0094] [Item 8] The quenching device according to item 6 or item 7, further comprising a gas suction unit configured to suck gas on the side of the water injection region among 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 disposed on both sides of the first wall portion and configured to sandwich the first wall portion, two pressing portions disposed on both sides of the second wall portion and configured to sandwich the second wall portion, further comprising, wherein the two pressing portions are configured to sandwich the second wall portion in a state where the second wall portion is pressed in a direction approaching the first wall portion.

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

Description of Symbols

[0097] 1... Workpiece, 2... Quenching device, 11... Top plate part, 12a... Right side wall part, 12b... Left side wall part, 13a... Right bending part, 13b... Left bending part, 21... Laser head, 22... Cover, 23... Water-cooled 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... Travel direction.

Claims

1. A quenching method for a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bending portion connecting the first wall portion and the second wall portion, comprising: heating the bending portion by irradiating the bending portion with a laser beam; cooling the heated bending portion by injecting water onto the bending portion following the irradiation of the laser beam; including: the water injection is performed in a state where a shielding member is disposed so as to separate the laser beam irradiation region and the water injection region.

2. The quenching method according to claim 1, wherein the water injection is performed in a state where the shielding member covers the water injection region and does not cover the laser beam irradiation region.

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

4. The quenching method according to claim 1 or 2, wherein the irradiation of the laser beam 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.

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

6. A quenching apparatus for a press-formed product having a first wall portion, a second wall portion intersecting the first wall portion, and a bending portion connecting the first wall portion and the second wall portion, comprising: a laser irradiation unit configured to irradiate the bending portion with a laser beam; a water injection unit configured to inject water onto the bending portion following the irradiation of the laser beam; a shielding member disposed so as to separate the laser beam irradiation region and the water injection region. The quenching apparatus comprising the above.

7. The quenching apparatus according to claim 6, wherein the shielding member is disposed so as to cover the water injection region and not cover the laser beam irradiation region.

8. The quenching apparatus according to claim 6 or 7, further comprising: a gas suction unit configured to suck gas on the side of the water injection region among the laser beam irradiation region and the water injection region separated by the shielding member.

9. The quenching device according to claim 6 or claim 7, wherein two fixing parts arranged on both sides sandwiching the first wall part and configured to sandwich the first wall part; two pressing parts arranged on both sides sandwiching the second wall part and configured to sandwich the second wall part; further comprising: The two pressing parts are configured to sandwich the second wall part in a state where the second wall part is pressed in a direction approaching the first wall part. The quenching device.

10. The quenching device according to claim 6 or claim 7, wherein the press-molded product is made of high-tensile steel. The quenching device.

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