QUENCHING METHOD, AND QUENCHING MACHINE

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Application No. 2024-003509 filed on Jan. 12, 2024 with the Japan Patent Office, and the entire disclosure of Japanese Patent Application No. 2024-003509 is incorporated herein by reference.

BACKGROUND

The present disclosure relates to a technique for quenching a press-formed product.

For example, Japanese Unexamined Patent Application Publication No. 2016-194132 discloses a method for quenching a steel plate as a workpiece. In this method, a heating process by irradiating a workpiece with a laser beam and a cooling process by spraying water on the heated workpiece are carried out successively.

SUMMARY

However, in the technique described in Japanese Unexamined Patent Application Publication No. 2016-194132, water vapor may be generated when the sprayed water for cooling is heated by the heated workpiece. In such cases, the water vapor may enter an irradiation area of the laser beam, and scatter the laser beam. If the water vapor scatters the laser beam, then quenching may become uneven.

In one aspect of the present disclosure, it is desirable to provide a technique for inhibiting scattering of a laser beam due to water for cooling when quenching a press-formed product.

One aspect of the present disclosure is a quenching method for a press-formed product having a first wall, a second wall intersecting the first wall, and a bend part coupling the first wall and the second wall. The quenching method comprises: heating the bend part by irradiating the bend part with a laser beam; and cooling the heated bend part by spraying water on the bend part, following irradiation of the laser beam. The water is sprayed with a shield being positioned to separate an irradiation area of the laser beam from a spray area of the water.

With the configuration as above, scattering of the laser beam due to the water for cooling can be inhibited when quenching is performed on the press-formed product.

In one aspect of the present disclosure, the water may be sprayed with the shield being positioned to cover the spray area of the water and not to cover the irradiation area of the laser beam. With the configuration as above, scattering of the laser beam due to the water for cooling can be further inhibited when quenching is performed on the press-formed product.

In one aspect of the present disclosure, the water may be sprayed with gas being suctioned on a side of the spray area of the water, out of the irradiation area of the laser beam and the spray area of the water separated by the shield. With the configuration as above, scattering of the laser beam due to the water for cooling can be further inhibited when quenching is performed on the press-formed product.

In one aspect of the present disclosure, irradiation of the laser beam and spraying of the water may be performed with the first wall being fixed and the second wall being pressed in a direction approaching the first wall. With the configuration as above, deformation due to the quenching can be less likely to occur.

One aspect of the present disclosure is a quenching machine for a press-formed product having a first wall, a second wall intersecting the first wall, and a bend part coupling the first wall and the second wall. The quenching machine comprises a laser irradiator, a water sprayer, and a shield. The laser irradiator is configured to irradiate the bend part with a laser beam. The water sprayer is configured to spray water on the bend part, following irradiation of the laser beam. The shield is positioned to separate an irradiation area of the laser beam from a spray area of the water.

With the configuration as above, scattering of the laser beam due to the water for cooling can be inhibited when quenching is performed on the press-formed product.

In one aspect of the present disclosure, the shield may be positioned to cover the spray area of the water and not to cover the irradiation area of the laser beam. With the configuration as above, scattering of the laser beam due to the water for cooling can be further inhibited when quenching is performed on the press-formed product.

In one aspect of the present disclosure, the quenching machine may further comprise a gas sucker configured to suction gas on a side of the spray area of the water, out of the irradiation area of the laser beam and the spray area of the water separated by the shield. With the configuration as above, when quenching is performed on the press-formed product, the water is sprayed with the gas being suctioned by the gas sucker. Thus, scattering of the laser beam due to the water for cooling can be further inhibited.

In one aspect of the present disclosure, the quenching machine may further comprise two fixers and two pressers. The fixers are disposed on opposite sides of the first wall and configured to hold the first wall therebetween. The pressers are disposed on opposite sides of the second wall and configured to hold the second wall therebetween. The two pressers may be configured to hold the second wall therebetween with the second wall being pressed in a direction approaching the first wall. With the configuration as above, deformation due to the quenching can be less likely to occur.

BRIEF DESCRIPTION OF THE DRAWINGS

An example embodiment of the present disclosure will be described hereinafter with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a workpiece;

FIG. 2 is a perspective view of the workpiece and a quenching machine;

FIG. 3A is a side view of the workpiece for explaining a positioning process in a quenching method of the workpiece;

FIG. 3B is a cross-sectional view of the workpiece taken along the line IIIB-IIIB in FIG. 3A;

FIG. 4A is a side view of the workpiece showing a state following FIG. 3A;

FIG. 4B is a cross-sectional view of the workpiece taken along the line IVB-IVB in FIG. 4A;

FIG. 5A is a side view of the workpiece and the quenching machine for explaining a quenching process in the quenching method of the workpiece;

FIG. 5B is a cross-sectional view of the workpiece and the quenching machine taken along the line VB-VB in FIG. 5A;

FIG. 6A is a side view of the workpiece and the quenching machine showing a state following FIG. 5A;

FIG. 6B is a cross-sectional view of the workpiece and the quenching machine taken along the line VIB-VIB in FIG. 6A;

FIG. 7A is a side view of the workpiece and the quenching machine showing a state following FIG. 6A;

FIG. 7B is a cross-sectional view of the workpiece taken along the line VIIB-VIIB in FIG. 7A;

FIG. 8A is a side view of the workpiece showing a state after the quenching process is completed in the quenching method of the workpiece;

FIG. 8B is a cross-sectional view of the workpiece taken along the line VIIIB-VIIIB in FIG. 8A;

FIG. 9 is a perspective view of a workpiece and a quenching machine for showing a modified example of a shield; and

FIG. 10 is a side view of the workpiece and the quenching machine for explaining a quenching process in a quenching method of the workpiece, using the quenching machine shown in FIG. 9.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
1. Configuration of Workpiece

FIG. 1 shows a workpiece 1 to be quenched in a quenching method and a quenching machine of the present disclosure. The workpiece 1 is a component of an automobile body, as an example. Examples of the component of the automobile body include automobile pillars and members. Terms related to directions used with respect to the workpiece 1 are for assisting readers in understanding the present disclosure, and are not intended to limit a used manner of the workpiece 1.

The workpiece 1 is a press-formed product produced by press-forming a steel plate. The steel plate, as an example, is a high-tensile steel with high tensile strength. The tensile strength of the high-tensile steel may be 590 MPa or greater, 780 MPa or greater, 980 MPa or greater, as an example. In the present embodiment, the tensile strength of the high-tensile steel is 1000 MPa. A plate thickness of the high-tensile steel is 1.0 mm to 3.0 mm, as an example.

As shown in FIG. 1, the workpiece 1 extends linearly. A direction in which the workpiece 1 extends is hereinafter referred to as an extending direction X. A cross-section of the workpiece 1 perpendicular to the extending direction X has a constant shape in the extending direction X. The cross-section of the workpiece 1 perpendicular to the extending direction X has a symmetrical shape.

The workpiece 1 has a top plate 11, a right side wall 12a, a left side wall 12b, a right bend part 13a, a left bend part 13b, a right flange 14a, and a left flange 14b.

The top plate 11 is a plate-like portion. Specifically, the top plate 11 is rectangular and flat when viewed from its front. Two long sides of the top plate 11 when viewed from the front are parallel to the extending direction X.

The right side wall 12a and the left side wall 12b are plate-like portions. Specifically, the right side wall 12a and the left side wall 12b are rectangular and flat when viewed from their front. In each of the right side wall 12a and the left side wall 12b, two long sides when viewed from the front are parallel to the extending direction X. The right side wall 12a and the left side wall 12b face each other. Each of the right side wall 12a and the left side wall 12b intersects the top plate 11. That the right side wall 12a or the left side wall 12b intersects the top plate 11 means, more precisely, that a virtual plane including the right side wall 12a or the left side wall 12b intersects a virtual plane including the top plate 11. Both an angle θa between the right side wall 12a and the top plate 11 and an angle θb between the left side wall 12b and the top plate 11 are, as an example, greater than 90 degrees. That is, the right side wall 12a and the left side wall 12b are inclined to the top plate 11 so that an interval between the right side wall 12a and the left side wall 12b increases in proportion to a distance from the top plate 11.

The right bend part 13a and the left bend part 13b are portions bent by press-forming. The right bend part 13a and the left bend part 13b are plates curved so that each plate thickness direction thereof is a radial direction of the workpiece 1. The right bend part 13a is positioned between the top plate 11 and the right side wall 12a. The right bend part 13a couples the top plate 11 and the right side wall 12a. The left bend part 13b is positioned between the top plate 11 and the left side wall 12b. The left bend part 13b couples the top plate 11 and the left side wall 12b.

In the following, of two surfaces of the right bend part 13a, a radially inner surface is referred to as an inner surface, and a radially outer surface thereof is referred to as an outer surface. Of two surfaces of the left bend part 13b, a radially inner surface is referred to as an inner surface, and a radially outer surface thereof is referred to as an outer surface. Of two surfaces of the right side wall 12a, a surface continuous to the inner surface of the right bend part 13a is referred to as an inner surface, and a surface continuous to the outer surface of the right bend part 13a is referred to as an outer surface. Of two surfaces of the left side wall 12b, a surface continuous to the inner surface of the left bend part 13b is referred to as an inner surface, and a surface continuous to the outer surface of the left bend part 13b is referred to as an outer surface. Of two surfaces of the top plate 11, a surface continuous to the respective inner surfaces of the right bend part 13a and the left bend part 13b is referred to as an inner surface, and a surface continuous to the respective outer surfaces of the right bend part 13a and the left bend part 13b is referred to as an outer surface.

The right flange 14a and the left flange 14b are plate-like portions. Specifically, the right flange 14a and the left flange 14b are rectangular and flat when viewed from their front. In each of the right flange 14a and the left flange 14b, two long sides are parallel to the extending direction X. The right flange 14a extends outward from an end face, of two end faces of the right side wall 12a extending along the extending direction X, on an opposite side of the top plate 11 side. “Outward” here means the opposite side of the top plate 11 side across the right side wall 12a. In other words, “outward” here is the outer surface side of the right side wall 12a. The left flange 14b extends outward from an end face, of two end faces of the left side wall 12b extending along the extending direction X, on an opposite side of the top plate 11 side. “Outward” here indicates the opposite side of the top plate 11 side across the left side wall 12b. In other words, “outward” here is the outer surface side of the left side wall 12b. The right flange 14a and the left flange 14b respectively extend from the right side wall 12a and the left side wall 12b in directions away from each other. Each of the right flange 14a and the left flange 14b extends substantially parallel to the top plate 11. In the following, of two surfaces of the right flange 14a, a surface continuous to the inner surface of the right side wall 12a is referred to as an inner surface, and a surface continuous to the outer surface of the right side wall 12a is referred to as an outer surface. Of two surfaces of the left flange 14b, a surface continuous to the inner surface of the left side wall 12b is referred to as an inner surface, and a surface continuous to the outer surface of the left side wall 12b is referred to as an outer surface.

While an automobile body is required to have high strength, high-strength materials are generally expensive in many cases. Thus, in some cases, as an example, by performing localized quenching on portions of a press-formed product that are required to have particularly high strength, the strength of the press-formed product as a whole can be increased. For the workpiece 1, as an example, quenching is locally performed on the right bend part 13a and the left bend part 13b. As an example, if quenching is locally performed on the right bend part 13a and the left bend part 13b of the workpiece 1 having a tensile strength before the quenching of 1000 MPa, then the tensile strength of the workpiece 1 as a whole becomes 1500 MPa.

2. Configuration of Quenching Machine

A quenching machine 2 shown in FIG. 2 is configured to perform quenching on the workpiece 1. Specifically, the quenching machine 2 is configured to perform quenching on the right bend part 13a and the left bend part 13b of the workpiece 1. As shown in FIGS. 2 and 6A, the quenching machine 2 comprises 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, two or more top plate cylinders 36, two or more side wall cylinders 37, a laser head 21, a cover 22, a water cooling nozzle 23, and a suction nozzle 24. These components of the quenching machine 2 are used in the same way when quenching the right bend part 13a and when quenching the left bend part 13b. Thus, respective components will be described below assuming that quenching is performed on the right bend part 13a.

As shown in FIG. 2, the workpiece 1 is placed in the quenching machine 2 with the top plate 11 side facing vertically upward and the right flange 14a and the left flange 14b sides 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 machine 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 and stainless steel. In the present embodiment, all of these jigs 31 to 35 are made of chromium copper.

Both the first top plate jig 31 and the second top plate jig 32 are prismatic. A cross-section of each of the first top plate jig 31 and the second top plate jig 32 perpendicular to an axial direction thereof has an approximately square shape. The first top plate jig 31 and the second top plate jig 32 are disposed on opposite sides of the top plate 11 of the workpiece 1 placed in the quenching machine 2. Specifically, as shown in FIGS. 2, 4A, and 4B, the first top plate jig 31 is disposed to face the inner surface of the top plate 11 with its axial direction being parallel to the inner surface of the top plate 11. The second top plate jig 32 is disposed to face the outer surface of the top plate 11 with its axial direction being parallel to the outer surface of the top plate 11.

A shown in FIG. 2, the two or more (three in the present embodiment) top plate cylinders 36 are disposed on a side of the second top plate jig 32 opposite to the top plate 11 side. The top plate cylinders 36 are configured to contact a surface of the second top plate jig 32. As an example, the top plate cylinders 36 are evenly spaced. The second top plate jig 32 is configured to be displaceable towards the top plate 11 side by extending respective rods of the top plate cylinders 36. By displacing the second top plate jig 32 towards the top plate 11 side, the top plate 11 is held 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 hold the top plate 11 therebetween.

The first side wall jig 33, the second side wall jig 34, and the third side wall jig 35 are all prismatic. A cross-section of each of the first side wall jig 33 and the second side wall jig 34 perpendicular to its axial direction has a rectangular shape. A cross-section of the third side wall jig 35 perpendicular to its axial direction has a triangular shape.

As shown in FIGS. 2, 4A, and 4B, the third side wall jig 35 is disposed at a right corner 15a, which is a corner formed by the right side wall 12a and the right flange 14a, of the workpiece 1 placed in the quenching machine 2. Specifically, the third side wall jig 35 is disposed to face the outer surface of the right side wall 12a and the outer surface of the right flange 14a with its axial direction being parallel to the outer surface of the right side wall 12a and the outer surface of the right flange 14a. The first side wall jig 33 is disposed on an opposite side of the third side wall jig 35 side across the right side wall 12a of the workpiece 1 placed in the quenching machine 2. Specifically, the first side wall jig 33 is disposed to face the inner surface of the right side wall 12a with its axial direction being parallel to the inner surface of the right side wall 12a. The second side wall jig 34 is disposed on an opposite side of the third side wall jig 35 side across the right flange 14a of the workpiece 1 placed in the quenching machine 2. Specifically, the second side wall jig 34 is disposed to face the inner surface of the right flange 14a with its axial direction being parallel to the inner surface of the right flange 14a.

The two or more (three in the present embodiment) side wall cylinders 37 are disposed on a side of the third side wall jig 35 opposite to the right corner 15a side. The side wall cylinders 37 are configured to contact a surface of the third side wall jig 35. As an example, the side wall cylinders 37 are evenly spaced. The third side wall jig 35 is configured to be displaceable towards the right corner 15a side by extending respective rods of the side wall cylinders 37. By displacing the third side wall jig 35 towards the right corner 15a side, the right side wall 12a is held between 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 hold the right side wall 12a therebetween. In addition, by displacing the third side wall jig 35 towards the right corner 15a side, the right flange 14a is held 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 hold the right flange 14a therebetween.

Specifically in the present embodiment, the third side wall jig 35 is configured to press the right side wall 12a in a direction approaching the top plate 11. In other words, the third side wall jig 35 is configured to press the right side wall 12a in a direction in which the angle θa between the top plate 11 and the right side wall 12a is reduced. The first side wall jig 33 and the third side wall jig 35 are configured to hold the right side wall 12a therebetween in a state where the right side wall 12a is pressed in the direction approaching the top plate 11.

The laser head 21 is a portion for irradiating the workpiece 1 with a laser beam. By irradiation of the laser beam by the laser head 21, the workpiece 1 is heated.

As shown in FIG. 2, the laser head 21 is disposed to face the right bend part 13a of the workpiece 1 fixed to the quenching machine 2. Specifically, the laser head 21 is disposed to face the outer surface of the right bend part 13a. A specific interval is left between the laser head 21 and the right bend part 13a. The laser head 21 is configured to be movable along a ridge line Ra of the right bend part 13a. In the following, a direction in which the laser head 21 moves while irradiating the right bend part 13a with the laser beam is referred to as a travel direction Y.

The water cooling nozzle 23 shown in FIG. 6A is a portion for spraying the water on the workpiece 1 heated by the irradiation of the laser beam. By spraying the water by the water cooling nozzle 23, the workpiece 1 is rapidly cooled.

As shown in FIG. 6B, the water cooling nozzle 23 is disposed to face the right bend part 13a of the workpiece 1 fixed to the quenching machine 2. Specifically, the water cooling nozzle 23 is disposed to face the outer surface of the right bend part 13a. A specific interval is left between the water cooling nozzle 23 and the right bend part 13a. As shown in FIG. 6A, the water cooling nozzle 23 is positioned behind the laser head 21 in the travel direction Y. The water cooling nozzle 23 is configured to be movable along the ridge line Ra of the right bend part 13a. The water cooling nozzle 23 is configured to be movable, following the laser head 21. As an example, the laser head 21 and the water cooling nozzle 23 have the same moving speed.

The water cooling nozzle 23 is configured to spray the water using a not shown pump. The water cooling nozzle 23 is configured to be movable following the irradiation of the laser beam, and thus can spray the water on the right bend part 13a following the irradiation of the laser beam by the laser head 21. Therefore, the water cooling nozzle 23 can spray the water to a high temperature portion of the outer surface of the right bend part 13a that has been heated by the irradiation of the laser beam.

<Cover>

The cover 22 is a member for inhibiting water vapor, which is generated by the water sprayed from the water cooling nozzle 23 being heated by the high temperature right bend part 13a, from entering an irradiation area of the laser beam. The irradiation area of the laser beam is an area where the irradiation of the laser beam is currently taking place. As the laser head 21 moves in the travel direction Y, the irradiation area of the laser beam also moves. The irradiation area of the laser beam can be also referred to as a light path of the laser beam.

The cover 22 is made of a water-and water vapor-impermeable material. 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 tubular shape with an opening on one side in its axial direction blocked. The cover 22 is positioned so that its axial direction is roughly aligned with the vertical direction. A vertically upper opening of the cover 22 is blocked. In other words, the cover 22 has a ceiling wall and a side wall, but does not have a bottom wall. A cross section of the cover 22 perpendicular to the axial direction has a quadrangular outer shape, as an example. 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, that opening is formed in the side wall of the cover 22 on a rear side in the travel direction Y.

The cover 22 is disposed to separate the irradiation area of the laser beam from a spray area of the water. Specifically, the cover 22 is disposed to cover the water cooling nozzle 23 from an opposite side of the workpiece 1 side, and not to cover the laser head 21. That is, the cover 22 is configured to cover the spray area of the water provided by the water cooling nozzle 23, and not to cover the irradiation area of the laser beam provided by the laser head 21. The spray area of the water is an area where spraying of the water is currently taking place. As the water cooling nozzle 23 moves in the travel direction Y, the spray area of the water also moves.

The cover 22 is configured to be movable along the ridge line Ra of the right bend part 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 bend part 13a at the same speed as the water cooling nozzle 23.

The suction nozzle 24 is configured to suction gas. A tip end of the suction nozzle 24 is disposed on a side of the spray area of the water, out of the irradiation area of the laser beam and the spray area of the water. That is, the suction nozzle 24 is configured to suction the gas on the side of the spray area of the water. 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 end of the suction nozzle 24 is disposed in the internal space of the cover 22. That is, the suction nozzle 24 is configured to suction the gas inside the cover 22. In the internal space of the cover 22, the tip end of the suction nozzle 24 is positioned behind the water cooling nozzle 23 in the travel direction Y. Thus, the suction nozzle 24 is configured to suction the gas rearward with respect to the water cooling nozzle 23 in the travel direction Y. The gas suctioned by the suction nozzle 24 is discharged to an outside of the cover 22. The “outside of the cover 22” herein indicates a space sufficiently away from the irradiation area of the laser beam, or a space that is closed and does not include the irradiation area of the laser beam. In other words, the gas suctioned by the suction nozzle 24 does not enter the irradiation area of the laser beam.

The suction nozzle 24 is configured to be movable along the ridge line Ra of the right bend part 13a integrally with the cover 22. That is, the cover 22, the water cooling nozzle 23, and the suction nozzle 24 are integrally movable in the travel direction Y, following the laser head 21.

3. Quenching Method

Next, with reference to FIGS. 3A to 8B, the quenching method of the workpiece 1 will be described. In FIGS. 5A to 7B, illustration of the top plate cylinders 36 and the side wall cylinders 37 is omitted. The quenching method of the workpiece 1 uses the above-described quenching machine 2. The quenching method of the workpiece 1 comprises at least a positioning process and a quenching process.

In the workpiece 1, quenching is performed on both the right bend part 13a and the left bend part 13b, as described above. Since the same method is used for quenching the right bend part 13a and quenching the left bend part 13b, respective processes will be described below assuming that the quenching is performed on the right bend part 13a.

The positioning process is a process to place the workpiece 1 in the quenching machine 2, and fix the workpiece 1. As shown in FIGS. 3A and 3B, the first top plate jig 31, the first side wall jig 33, and the second side wall jig 34 are disposed in the quenching machine 2. The first top plate jig 31, the first side wall jig 33, and the second side wall jig 34 are positioned so that their axial directions are parallel to each other. The first side wall jig 33 and the second side wall jig 34 are positioned to form an angle corresponding to the right corner 15a of the workpiece 1. The first top plate jig 31 is positioned so that its upper surface is vertically above an upper surface of the second side wall jig 34 by a height corresponding to a height from the right flange 14a to the top plate 11 of the workpiece 1.

In the positioning process, the workpiece 1 is firstly placed on the first top plate jig 31, the first side wall jig 33, and the second side wall jig 34 in the quenching machine 2 with the top plate 11 side facing vertically upward and the right flange 14a and the left flange 14b side facing vertically downward. With the workpiece 1 placed in the quenching machine 2, the inner surface of the top plate 11 is in contact with a vertically upper side surface of the first top plate jig 31. In addition, a vertically upper side surface of the second side wall jig 34 is in contact with the inner surface of the right flange 14a. Thus, a surface of the first side wall jig 33 on the right side wall 12a side and the inner surface of the right side wall 12a face each other.

Next, as shown in FIGS. 4A and 4B, the second top plate jig 32 is placed on the outer surface of the top plate 11 with its axial direction being parallel to the axial direction of the first top plate jig 31. The second top plate jig 32 is positioned so that the first top plate jig 31 and the second top plate jig 32 overlap each other with the top plate 11 being interposed therebetween in plan view. Subsequently, the top plate cylinders 36 are disposed on an opposite side of the second top plate jig 32 with respect to the top plate 11 side. By extending the respective rods of the top plate cylinders 36, the second top plate jig 32 is displaced to the first top plate jig 31 side. As a result, the top plate 11 is held between the first top plate jig 31 and the second top plate jig 32. When the top plate 11 is held between the first top plate jig 31 and the second top plate jig 32, the workpiece 1 is fixed to the quenching machine 2.

Next, the third side wall jig 35 is disposed in the right corner 15a with its axial direction being parallel to the respective outer surfaces of the right side wall 12a and the right flange 14a. Subsequently, the side wall cylinders 37 are disposed on an opposite side of the third side wall jig 35 with respect to the right corner 15a side. By extending the respective rods of the side wall cylinders 37, the third side wall jig 35 is displaced to the first side wall jig 33 side. Then, the third side wall jig 35 presses the right side wall 12a in a direction approaching the top plate 11. In other words, the third side wall jig 35 presses the right side wall 12a in a direction in which the angle θa between the top plate 11 and the right side wall 12a is reduced. The third side wall jig 35 holds the right side wall 12a between the first side wall jig 33 and the third side wall jig 35. In this way, the right side wall 12a is held between the first side wall jig 33 and the third side wall jig 35 in a state where the right side wall 12a is pressed in a direction approaching the top plate 11.

When quenching is performed on the right bend part 13a, the workpiece 1 may be deformed due to heating and rapid cooling of the right bend part 13a so that the angle θa between the top plate 11 and the right side wall 12a increases (so-called heat distortion may occur). Thus, in the positioning process of the present embodiment, as described above, the third side wall jig 35 presses the right side wall 12a in an opposite direction of deformation expected by the quenching. Pressing the right side wall 12a as such is also referred to as applying preset distortion to the right side wall 12a.

When the positioning process is completed, the workpiece 1 is placed and fixed in the quenching machine 2. In the present embodiment, the workpiece 1 is fixed to the quenching machine 2 with preset distortion applied to the right side wall 12a.

The quenching process is a process to perform quenching on the right bend part 13a of the workpiece 1. The quenching process follows the positioning process. In the present embodiment, since the workpiece 1 is fixed to the quenching machine 2 with preset distortion applied to the right side wall 12a in the positioning process, quenching is performed on the workpiece 1 in the quenching process with the preset distortion applied as such.

First, as shown in FIGS. 5A and 5B, the laser head 21 is disposed to face a quenching start position on the outer surface of the right bend part 13a. In the present embodiment, the quenching start position is set to one end of the right bend part 13a in the ridge line Ra direction. The water cooling nozzle 23 is disposed above the workpiece 1 (that is, on the same side as the laser head 21 with respect to the right bend part 13a) and behind the laser head 21 in the travel direction Y. The suction nozzle 24 is disposed behind the water cooling nozzle 23 in the travel direction Y. That is, the laser head 21, the water cooling nozzle 23, and the suction nozzle 24 are disposed in this order from a front side in the travel direction Y. The cover 22 is positioned to separate the irradiation area of the laser beam from the spray area of the water. In the present embodiment, the cover 22 is disposed to cover the water cooling nozzle 23 and the tip end of the suction nozzle 24 vertically from above.

The laser head 21, the cover 22, the water cooling nozzle 23, and the suction nozzle 24 all start moving in the travel direction Y at the same speed. That is, these components start moving in the travel direction Y integrally. The laser head 21 starts the irradiation of the laser beam as it starts moving. The water cooling nozzle 23 starts spraying of the water as it starts moving. The suction nozzle 24 starts suctioning the gas inside the cover 22 as it starts moving. The water is sprayed by the water cooling nozzle 23 on the side of the spray area of the water, out of the irradiation area of the laser beam and the spray area of the water separated by the cover 22, with the gas being suctioned by the suction nozzle 24.

As shown in FIGS. 6A and 6B, the laser head 21 irradiates the outer surface of the right bend part 13a with the laser beam while moving in the travel direction Y. Strength of the laser beam and a moving speed of the laser head are set to a strength and a moving speed which allow the right bend part 13a to be heated to or above a temperature at which austenitization starts. In the present embodiment, the strength of the laser beam and the moving speed of the laser head are set so that the right bend part 13a is heated to a temperature of 900° C. or higher.

The water cooling nozzle 23 sprays the water on the outer surface of the right bend part 13a while moving in the travel direction Y, following the laser head 21. An amount of the water sprayed is set to an amount that allows cooling the right bend part 13a to or below a temperature at which martensitic transformation occurs at the moving speed of the laser head 21. In the present embodiment, the amount of the water sprayed is set so that the right bend part 13a is rapidly cooled to a temperature of 200° C. or lower.

The cover 22 moves in the travel direction Y at the same speed as the water cooling nozzle 23 and the laser head 21, with the water cooling nozzle 23 and the tip end of the suction nozzle 24 being covered vertically from above. Thus, the water is sprayed by the water cooling nozzle 23 with the cover 22 being positioned to separate the irradiation area of the laser beam from the spray area of the water. In the present embodiment, the water is sprayed by the water cooling nozzle 23 in a state where the spray area of the water is covered by the cover 22 and the irradiation area of the laser beam is not covered.

Since the right bend part 13a is heated to high temperature by the irradiation of the laser beam, the water sprayed on the right bend part 13a vaporizes into water vapor. The suction nozzle 24 suctions the water vapor while moving in the travel direction Y. The suction nozzle 24 can suction air inside the cover 22, evaporation products of rust preventive oil and plating on the surface of the workpiece 1, etc., in addition to the water vapor. That is, the suction nozzle 24 suctions substances that can be a disturbance to the laser beam. The suctioned water vapor and other substances are discharged to the outside of the cover 22 via the suction nozzle 24.

As shown in FIGS. 7A and 7B, the laser head 21, the cover 22, the water cooling nozzle 23, and the suction nozzle 24 move along the travel direction Y while performing their respective processes until the water cooling nozzle 23 reaches an end of the right bend part 13a opposite to the quenching start position in the ridge line Ra direction. When the right bend part 13a is heated by the irradiation of the laser beam and cooled by the spraying of the water over the entire length of the right bend part 13a in the ridge line Ra direction, the quenching process is completed.

Lastly, as shown in FIGS. 8A and 8B, the workpiece 1 is removed from the quenching machine 2 by reversing the procedure of the positioning process described above.

4. Effect

According to the embodiment detailed above, the following effects can be obtained.

(4a) In the present embodiment, cooling by spraying the water on the workpiece 1 follows heating by irradiating the workpiece 1 with the laser beam. The water is sprayed with the cover 22 being positioned to separate the irradiation area of the laser beam from the spray area of the water. Specifically, the water is sprayed with the cover 22 being positioned to cover the spray area of the water and not to cover the irradiation area of the laser beam.

With the configuration as above, even if the sprayed water is heated by the high-temperature right bend part 13a and turned into water vapor when quenching is performed on the workpiece 1, it is possible to inhibit the water vapor from entering the irradiation area of the laser beam since the spray area of the water is covered by the cover 2. Thus, scattering of the laser beam by the water vapor can be inhibited, facilitating uniform quenching over the entire length of the right bend part 13a.

(4b) In the present embodiment, the water is sprayed with the gas being suctioned on the side of the spray area of the water, out of the irradiation area of the laser beam and the spray area of the water separated by the cover 22. Specifically, the water is sprayed with the gas inside the cover 22 being suctioned. With the configuration as above, even if the sprayed water is heated by the high-temperature right bend part 13a and turned into water vapor when quenching is performed on the workpiece 1, it is possible to inhibit the water vapor from leaking out of the cover 22 and entering the irradiation area of the laser beam. Thus, compared to a case where the water is sprayed without the gas inside the cover 22 being suctioned, scattering of the laser beam due to the water vapor can be further inhibited. As a result, it becomes easier to perform quenching more uniformly over the entire length of the right bend part 13a.

(4c) In the present embodiment, the irradiation of the laser beam and the spraying of the water are performed with the top plate 11 being fixed and the right side wall 12a being pressed in the direction approaching the top plate 11. With the configuration as above, deformation due to the quenching can be less likely to occur. Thus, it is possible to easily maintain a design shape of the workpiece 1 throughout pre-and post-quenching processes, and the workpiece 1 can be easily assembled in the post-quenching process.

(4d) According to the present embodiment, it is possible to provide the quenching machine 2 that achieves the effects described in (4a) through (4c) above.

In the present embodiment, the case where the quenching is performed on the right bend part 13a is described. However, the same effects as in (4a) through (4d) can be obtained when the quenching is performed on the left bend part 13b.

5. Correspondence Relation between Terms

In the present embodiment, the workpiece 1 corresponds to an example of a press-formed product.

The top plate 11 corresponds to an example of a first wall, the right side wall 12a and the left side wall 12b correspond to an example of a second wall, and the right bend part 13a and the left bend part 13b correspond to an example of a bend part.

The laser head 21 corresponds to an example of a laser irradiator, the cover 22 corresponds to an example of a shield, the water cooling nozzle 23 corresponds to an example of a water sprayer, and the suction nozzle 24 corresponds to an example of a gas sucker.

The first top plate jig 31 and the second top plate jig 32 correspond to an example of two fixers, and the first side wall jig 33 and the third side wall jig 35 correspond to an example of two pressers.

6. Other Embodiments

An embodiment of the present disclosure has been described in the above. However, the present disclosure is not limited to the above-described embodiment, and may take various forms.

(6a) In the above-described embodiment, the cover 22 has a bottomed tubular shape that covers the water cooling nozzle 23 vertically from above. However, the shape of the cover 22 is not particularly limited. As an example, the cover 22 may have a hemispherical shape covering the water cooling nozzle 23 vertically from above.

(6b) In the above-described embodiment, the cover 22 is shown as an example of the shield. The cover 22 covers the water cooling nozzle 23 vertically from above. However, the shield does not necessarily have to cover the water cooling nozzle 23 vertically from above. As shown in FIGS. 9 and 10, the shield may be a plate-like 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 irradiation area of the laser beam from the spray area of the water. Also with this configuration, the same effects as in (4a) through (4d) are achieved.

(6c) In the above-described embodiment, one laser head 21 irradiates the outer surface of the right bend part 13a with the laser beam. However, there are no particular limitations on the number of the laser heads 21 that irradiate the outer surface of the right bend part 13a with the laser beam. As an example, two laser heads 21 may irradiate the outer surface of the right bend part 13a with the laser beam. In this case, one of the two laser heads 21 may be positioned to face the top plate 11, and the other may be positioned to face the right side wall 12a. By positioning the two laser heads 21 as above, the right bend part 13a may be irradiated with the laser beam. As another example, three or more laser heads 21 may irradiate the right bend part 13a with the laser beam.

(6d) In the above-described embodiment, the outer surfaces of the right bend part 13a and the left bend part 13b are irradiated with the laser beam. However, there are no particular limitations on which surfaces of the right bend part 13a and the left bend part 13b are irradiated with the laser beam. As an example, the inner surfaces of the right bend part 13a and the left bend part 13b may be irradiated with the laser beam.

(6e) In the above-described embodiment, the water is sprayed on the outer surfaces of the right bend part 13a and the left bend part 13b. However, there are no particular limitations on which surfaces of the right bend part 13a and the left bend part 13b are sprayed by the water. As an example, in addition to the outer surfaces of the right bend part 13a and the left bend part 13b, the water may be sprayed also on the inner surfaces of the right bend part 13a and the left bend part 13b. For each of the right bend part 13a and the left bend part 13b, simultaneous spraying of the water on both the outer surface and the inner surface can improve cooling efficiency. As another example, in place of the outer surfaces of the right bend part 13a and the left bend part 13b, the water may be sprayed on the inner surfaces of right bend part 13a and the left bend part 13b.

(6f) In the above-described embodiment, the irradiation of the laser beam and the spraying of the water are performed on the right bend part 13a and the left bend part 13b. However, the irradiation of the laser beam and the spraying of the water may be performed on portions other than the right bend part 13a and the left bend part 13b. As an example, the outer surfaces of the right bend part 13a and the left bend part 13b as well as peripheries of the outer surfaces may be irradiated with the laser beam and sprayed with the water.

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

(6h) In the above-described embodiment, the workpiece 1 has the top plate 11, the right side wall 12a, the left side wall 12b, the right bend part 13a, the left bend part 13b, the right flange 14a, and the left flange 14b. However, the shape of the workpiece 1 is not particularly limited. As an example, the workpiece 1 does not have to have flanges. As an example, the workpiece 1 may have a single side wall and a single bend part instead of multiple side walls and bend parts.

(6i) In the above-described embodiment, relative movement between the workpiece 1, and the laser head 21, the cover 22, the water cooling nozzle 23 and the suction nozzle 24 is achieved by moving the laser head 21, the cover 22, the water cooling nozzle 23 and the suction nozzle 24. However, mode of the relative movement between the workpiece 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 achieved by moving the workpiece 1, or may be achieved by moving both the workpiece 1, and the laser head 21, the cover 22, the water cooling nozzle 23 and the suction nozzle 24.

(6j) In the above-described embodiment, the top plate cylinders 36 and the side wall cylinders 37 are used to displace the second top plate jig 32 and the third side wall jig 35. However, mode of displacing these jigs is not particularly limited. As an example, in place of, or in addition to, the top plate cylinders 36 and the side wall cylinders 37, at least one clamp may be used.

(6k) In the above-described embodiment, the quenching machine 2 comprises the suction nozzle 24. However, in the quenching machine 2, the water vapor does not necessarily have to be suctioned. In other words, the quenching machine 2 does not have to comprise the suction nozzle 24.

(6l) In the above-described embodiment, the workpiece 1 is made of a high-tensile steel with high tensile strength. However, types of steel materials that make up the workpiece is not particularly limited. As an example, the workpiece 1 may be made of a steel material other than high-tensile steel.

(6m) A function/functions of one element in the above-described embodiments may be distributed as two or more elements, or a function/functions of two or more elements may be integrated into one element. Part of the configuration of the above-described embodiments may be omitted. At least part of the configuration of the above-described embodiments may be added to or replaced with a configuration of other embodiments.

Technical Idea Disclosed in Present Specification
[Item 1]

A quenching method for a press-formed product having a first wall, a second wall intersecting the first wall, and a bend part coupling the first wall and the second wall, the quenching method comprising:

- heating the bend part by irradiating the bend part with a laser beam; and
- cooling the heated bend part by spraying water on the bend part, following irradiation of the laser beam,
- the water being sprayed with a shield being positioned to separate an irradiation area of the laser beam from a spray area of the water.

[Item 2]

The quenching method according to Item 1, wherein

- the water is sprayed with the shield being positioned to cover the spray area of the water and not to cover the irradiation area of the laser beam.

[Item 3]

The quenching method according to Item 1 or 2, wherein

- the water is sprayed with gas being suctioned on a side of the spray area of the water, out of the irradiation area of the laser beam and the spray area of the water separated by the shield.

[Item 4]

The quenching method according to any one of Items 1 to 3, wherein

- irradiation of the laser beam and spraying of the water are performed with the first wall being fixed and the second wall being pressed in a direction approaching the first wall.

[Item 5]

The quenching method according to any one of Items 1 to 4, wherein

- the press-formed product is made of a high-tensile steel.

[Item 6]

A quenching machine for a press-formed product having a first wall, a second wall intersecting the first wall, and a bend part coupling the first wall and the second wall, the quenching machine comprising:

- a laser irradiator configured to irradiate the bend part with a laser beam;
- a water sprayer configured to spray water to the bend part, following irradiation of the laser beam; and
- a shield positioned to separate an irradiation area of the laser beam from a spray area of the water.

[Item 7]

The quenching machine according to Item 6, wherein

- the shield is positioned to cover the spray area of the water and not to cover the irradiation area of the laser beam.

[Item 8]

The quenching machine according to Item 6 or 7, further comprising:

- a gas sucker configured to suction gas on a side of the spray area of the water, out of the irradiation area of the laser beam and the spray area of the water separated by the shield.

[Item 9]

The quenching machine according to any one of Items 6 to 8, further comprising:

- two fixers disposed on opposite sides of the first wall and configured to hold the first wall therebetween; and
- two pressers disposed on opposite sides of the second wall and configured to hold the second wall therebetween, wherein
- the two pressers are configured to hold the second wall therebetween with the second wall being pressed in a direction approaching the first wall.

[Item 10]

The quenching machine according to any one of Items 6 to 9, wherein

- the press-formed product is made of a high-tensile steel.

QUENCHING METHOD, AND QUENCHING MACHINE

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

International Classifications

Abstract

Description

Claims

Priority Claims (1)