JP7052472B2 - Grooving method, grooving equipment and steel sheet - Google Patents

Description

The present invention relates to a grooving method, a grooving apparatus and a steel sheet.

In recent years, steel sheets having a functional film on the surface have been developed in order to improve the functionality of steel sheets. Patent Document 1 discloses that a groove is formed on the surface of a steel sheet by a laser beam in order to improve the adhesion of the functional film to the surface of the steel sheet. Further, as a method for processing a groove, Patent Document 2 describes that while spraying an assist gas on an irradiated portion of a laser beam, the steel sheet is irradiated with the laser beam at a predetermined angle, and a melt or the like is discharged from the gas pressure of the assist gas. It is disclosed that a groove is formed on the surface of a steel sheet while being removed from the surface of the steel sheet.

International Publication No. 2014/156989 International Publication No. 2016/171130

Although Patent Document 1 and Patent Document 2 disclose a laser output of 1000 W or less, in reality, a short pulse having a high peak output is required to surely form a deep groove of 20 μm or more on the surface of the steel plate. It was necessary to use a laser light source or a laser light source having a laser output of more than 1000 W with a continuous wave laser, and to machine the groove mainly by the evaporation phenomenon of the molten portion. Therefore, when processing a deep groove, it is necessary to use an expensive high-power laser light source, which increases equipment cost and running cost, which causes a problem of high cost.

Further, in Patent Document 1, although irregular irregularities can be formed on the surface of a steel sheet by using a laser beam to form grooves, conditions for stably forming desired concave grooves are clearly disclosed. Therefore, it is difficult to stably process a groove having a desired shape from the disclosed contents of Patent Document 1.

In Patent Document 2, since the melt is blown off by using the assist gas to form the groove, it is necessary to increase the flow rate and the gas pressure of the assist gas. Therefore, in Patent Document 2, the shape of the molten portion may be deformed by the assist gas, and it is difficult to stably process a groove having a desired shape.

The present invention has been made in view of the above problems, and provides a grooving method, a grooving device, and a steel plate capable of machining a groove having a desired shape and reducing costs. The purpose is.

The grooving method of the present invention is a grooving method for grooving a steel plate surface with a laser beam, in which the laser beam emitted from a laser light source is applied to a plane including a normal line of the steel plate surface and the laser beam. An irradiation step of irradiating the surface of the steel plate at a predetermined angle from the normal line, a moving step of moving the steel plate relative to the laser light source at 1.5 m / s or more and 100 m / s or less, and the laser. A laser output control step of setting the laser output of the light source to 100 W or more and 1000 W or less is provided.
When the steel plate is melted and processed by the laser beam to make the groove depth 10.5 μm or more and 50 μm or less, and the groove is viewed in the groove width direction cross section orthogonal to the groove extension direction, the groove opening end width The center of the groove is defined as the groove opening center line, and the melt-solidified portion formed around the groove inside the steel plate is divided into a first melt-solidified portion and a second melt-solidified portion with the groove opening center line as a boundary. When separated, the first melt solidification portion on the incident side of the laser beam and the second melt on the non-incident side of the laser beam are separated along the groove extension direction with the groove opening center line as a boundary. The solidified portion has an asymmetrical shape, and the first melt-solidified portion is formed larger than the second melt-solidified portion.

Further, the grooving apparatus of the present invention is a grooving apparatus for processing a groove on a steel plate surface by a laser beam, in which the laser beam is emitted from the normal line in a plane including the normal line of the steel plate surface and the laser beam. A laser light source that irradiates the surface of the steel plate at a predetermined angle, a moving mechanism that moves the steel plate relative to the laser light source at 1.5 m / s or more and 100 m / s or less, and a laser output of the laser light source of 100 W. It is equipped with a laser output control unit with a voltage of 1000 W or less.
When the steel plate is melted and processed by the laser beam to make the groove depth 10.5 μm or more and 50 μm or less, and the groove is viewed in the groove width direction cross section orthogonal to the groove extension direction, the groove opening end width The center of the groove is defined as the groove opening center line, and the melt-solidified portion formed around the groove inside the steel plate is divided into a first melt-solidified portion and a second melt-solidified portion with the groove opening center line as a boundary. When separated, the first melt solidification portion on the incident side of the laser beam and the second melt on the non-incident side of the laser beam are separated along the groove extension direction with the groove opening center line as a boundary. The solidified portion has an asymmetrical shape, and the first melt-solidified portion is formed larger than the second melt-solidified portion.

Further, in the steel plate of the present invention, in a steel plate having a groove formed on the surface of the steel plate, the groove depth is 10.5 μm or more and 50 μm or less, and the groove is seen in a groove width direction cross section orthogonal to the groove extension direction. In this case, the center of the groove opening end width is defined as the groove opening center line, and the melt-solidified portion formed around the groove inside the steel plate is referred to as the first melt-solidified portion with the groove opening center line as a boundary. When divided into a second melt-solidified portion, the first melt-solidified portion and the second melt-solidified portion have an asymmetric shape along the groove extending direction with the groove opening center line as a boundary, and the first The melt-solidified portion is formed to be larger than the second melt-solidified portion.

According to the present invention, it is possible to form a groove having a desired shape on the surface of a steel sheet by controlling the flow of hot water in a molten portion while achieving a low output laser output, without using an assist gas for blowing off the melt or a high output laser light source. A groove having a desired shape can be machined. In addition, the cost can be reduced because the assist gas for blowing off the melt and the high-power laser light source are not required.

It is a schematic diagram which shows the whole structure of the groove processing apparatus by 1st Embodiment. It is a schematic diagram for demonstrating in detail about a steel plate and a laser beam. FIG. 3A is a schematic view showing the configuration of the groove width direction cross section at the beginning of laser light irradiation in AA ′ of FIG. 2, and FIG. 3B shows the configuration of the groove width direction cross section during laser light irradiation. It is a schematic diagram. It is a cross section in the groove width direction in BB'in FIG. 2, and is a schematic view showing a detailed configuration of a groove processed into a steel plate. It is a photograph when the groove when processed by changing the scanning speed with a laser output of 175 W and an irradiation angle of 45 degrees is observed with an optical microscope, and FIG. 5A is a photograph when the scanning speed is 1.0 m / s. 5B is a photograph when the scanning speed is 1.5 m / s, and FIG. 5C is a photograph when the scanning speed is 2.0 m / s. It is a photograph when the cross section in the groove width direction of the groove when machined by changing the scanning speed with a laser output of 175 W and an irradiation angle of 45 degrees is observed by SEM, and FIG. 6A shows a scanning speed of 1.0 m / s. 6B is a photograph when the scanning speed is 1.5 m / s, and FIG. 6C is a photograph when the scanning speed is 2.0 m / s. It is a photograph when the groove when processed by changing the scanning speed with a laser output of 200 W and an irradiation angle of 45 degrees is observed with an optical microscope, and FIG. 7A is a photograph when the scanning speed is 1.0 m / s. 7B is a photograph when the scanning speed is 1.5 m / s, and FIG. 7C is a photograph when the scanning speed is 2.0 m / s. It is a photograph when the cross section in the groove width direction of the groove when processed by changing the scanning speed with a laser output of 200 W and an irradiation angle of laser light of 45 degrees is observed by SEM. FIG. 8A shows a scanning speed of 1.0 m / s. 8B is a photograph when the scanning speed is 1.5 m / s, and FIG. 8C is a photograph when the scanning speed is 2.0 m / s. It is a schematic diagram which shows the whole structure of the groove processing apparatus by 2nd Embodiment. FIG. 10A is a schematic view showing a state in which a laser beam is applied to an inclined steel plate in the groove processing apparatus shown in FIG. 9, and FIG. 10B shows a state after a lapse of a predetermined time from FIG. 10A. It is a schematic diagram. 11A is _a schematic view showing the groove width direction cross section S1 at the beginning of laser light irradiation shown in FIG. 10A, and FIG. 11B is _a schematic view showing the groove width direction cross section S1 during laser light irradiation. be. It is the schematic which showed the cross section _S1 in the groove width direction shown in FIG. 10B. It is a photograph when the surface of a steel plate when a groove is machined without using a shield gas is photographed by SEM with a laser output of 200 W, an irradiation angle of laser light of 40 degrees, and a scanning speed of 2.0 m / s. It is a photograph when the groove width direction cross section of the groove when processed by changing the gas pressure of the shield gas with a laser output of 200 W, a laser beam irradiation angle of 40 degrees, and a scanning speed of 2.0 m / s is observed by SEM. 14A is a photograph when the shield gas is not used, FIG. 14B is a photograph when the gas pressure of the shield gas is 0.1 MPa, and FIG. 14C is a photograph when the gas pressure of the shield gas is 1.0 MPa. be. It is a photograph when the cross section in the groove width direction of the groove when processed by changing the scanning speed with a laser output of 200 W and an irradiation angle of laser light of 40 degrees is observed by SEM. FIG. 15A shows a scanning speed of 1.0 m / s. 15B is a photograph when the scanning speed is 1.5 m / s, and FIG. 15C is a photograph when the scanning speed is 2.0 m / s. It is a photograph when the cross section in the groove width direction of the groove when processed by changing the scanning speed with a laser output of 150 W and an irradiation angle of 45 degrees of the laser light is observed by SEM, and FIG. 16A shows a scanning speed of 1.0 m / s. 16B is a photograph when the scanning speed is 1.5 m / s, and FIG. 16C is a photograph when the scanning speed is 2.0 m / s.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals will be given to the same configurations, and duplicate description will be omitted.

(1) First Embodiment <Structure of Grooving Device According to First Embodiment>
FIG. 1 is a schematic view showing the overall configuration of the grooving apparatus 1 of the present invention for machining a groove in a steel plate 5. The grooving apparatus ₁ irradiates the steel plate surface 5a with the laser beam L1 from a predetermined angle while moving the steel plate 5 in the X direction. As a result, the groove processing apparatus ₁ can process the groove at the irradiation position (position along _ax2 in the figure) irradiated with the laser beam L1 on the steel plate surface 5a. In FIG. 1, the X direction is the groove extending direction in which the groove is formed, Z indicates the normal direction parallel to the normal line a _x1 of the steel plate surface 5a, and Y indicates the groove extending direction X and the normal line. The groove width direction orthogonal to the direction Z is shown.

In this case, the groove processing device 1 has a laser light source 2 that emits a laser beam L ₁ , a laser output control unit 6, and a moving mechanism 7. The laser light L1 emitted from the laser light source ₂ is focused by the lens 3 and then irradiated on the steel plate surface 5a. The steel plate 5 is formed with _a concave groove on the surface 5a of the steel plate by melting and solidifying the irradiation position of the laser beam L1. At this time, the power density of the laser beam L ₁ on the steel plate surface 5a is a key hole (KH shown in FIG. 3B described later, which is KH shown in FIG. 3B described later) in the molten portion by the laser beam L ₁ during irradiation of the laser beam L ₁ . _A columnar hole in the molten metal (melted portion) extending in the optical axis direction of the laser beam L1 temporarily generated by the heat of ₁ and the pressure of the metal steam gas generated thereby) is formed. Since it is necessary, it is desirable that it is 1 MW / cm ² or more.

In the laser light source ₂ , the laser light L1 is tilted by _a predetermined angle θ1 from the normal line _ax1 in a plane including the normal line _{a x1} of the steel plate surface 5a and the optical axis of the laser light L1, and the steel plate surface 5a. _The laser beam L1 is irradiated from an oblique direction with respect to the light. More specifically, in the case of the present embodiment, the normal line _{a x1} and the optical axis of the laser beam L1 are formed in _a plane including the normal line _ax1 of the steel plate surface 5a and the optical axis of the laser beam L1. It is desirable that the angle (hereinafter, also referred to as irradiation angle) θ ₁ is set to 20 degrees or more and 80 degrees or less.

If the irradiation angle θ ₁ of the laser beam L ₁ is less than 20 degrees, it is difficult to machine a groove having a desired shape in which the molten portion formed around the groove inside the steel plate 5 is unevenly distributed. On the other hand, when the irradiation angle θ ₁ is set to more than 80 degrees, the laser beam L1 is reflected by the steel plate surface 5a, and it is difficult to machine _a groove having a desired depth. Therefore, it is desirable that the irradiation angle θ ₁ of the laser beam L ₁ is 20 degrees or more and 80 degrees or less.

Here, the principle of groove processing according to the present invention is considered as follows. When the groove is machined by the laser beam L1, _a columnar cavity made of metal steam called _a keyhole (shown in FIG. 3B described later) is formed _on the optical axis of the laser beam L1 at the irradiation site of the laser beam L1. It is formed diagonally along. As a result, the melt bursts at the inner tip of the keyhole (shown by 10b in FIG. 3B, where the amount of melt is small and the skin is thin), and the metal vapor gas is not incident _on the laser beam L1. Exit from the side to the outside. At this time, since the surroundings are in a solid phase, the melt is pushed by the reaction force. Therefore, it is considered that a melt-solidified convex portion or the like, which will be described later, is formed, or the melt-solidified portion is unevenly distributed on the incident side and the non _- incident side of the laser beam L1.

When the irradiation angle θ ₁ is 45 degrees or less, the amount of the melt pushed away by the metal vapor gas is large, so that the flow of the melt becomes unstable and the groove shape may not always be stable. On the other hand, when the irradiation angle θ ₁ is 75 degrees or more, the laser beam L ₁ is projected, so that it may be difficult to form a keyhole. Therefore, the irradiation angle θ ₁ of the laser beam L ₁ is more preferably more than 45 degrees and less than 75 degrees.

In this embodiment, as shown in FIG. 1, the irradiation angle θ ₁ of the laser beam L ₁ is defined with respect to the normal a _x 1 in the plane formed by the groove width direction Y and the normal direction Z. However, the present invention is not limited to this. In the present invention, the irradiation angle θ ₁ of the laser beam L ₁ may be defined with respect to the normal line a _x 1 in the plane including the normal line a _x 1 of the steel plate surface 5a and the optical axis of the laser beam L ₁ . For example, the laser beam L ₁ may be tilted by an irradiation angle θ ₁ with respect to the normal line a _x 1 in the plane outside the plane formed by the groove width direction Y and the normal direction Z.

The laser output control unit 6 is connected to the laser light source 2 and controls the laser output of the laser light source 2 to 100 W or more and 1000 W or less, more preferably 150 W or more and 900 W or less. If the laser output is less than 100 W, the laser output is too weak and it becomes difficult to machine a groove having a desired shape. On the other hand, when the laser output exceeds 1000 W, the laser output becomes high, and equipment cost, running cost, etc. are incurred, resulting in high cost. Therefore, it is desirable that the laser output is 100 W or more and 1000 W or less.

Further, when the laser output is more preferably 150 W or more and 900 W or less, a relatively inexpensive single-mode fiber laser can be used as the laser light source 2.

The moving mechanism 7 scans the laser beam L1 with respect to the steel plate surface 5a by moving the steel plate 5 in the X direction at _a predetermined scanning speed. In this case, it is desirable that the steel plate 5 is moved at a scanning speed of 1.5 m / s or more and 100 m / s or less, more preferably 2 m / s or more and 90 m / s or less. If the scanning speed is less than 1.5 m / s, the amount of melt on the keyhole becomes large and cannot be completely eliminated, so that a significant groove depth cannot be obtained. On the other hand, when the scanning speed is more than 100 m / s, the total amount of melting is reduced, so that a significant groove depth cannot be obtained.

Further, when the scanning speed is set to more preferably 2 m / s or more and 90 m / s or less, the balance between the melt amount and the exclusion pressure (pressure at which the metal vapor gas excludes the melt) at the irradiation _point of the laser beam L1 is good. Therefore, a stable and significant groove depth can be obtained.

<Regarding the groove machined by the groove processing apparatus of the present invention>
Next, the groove machined by the groove processing apparatus 1 of the present invention will be described in detail. As shown in FIG. 2, the steel plate 5 is moved in the X direction orthogonal to the normal direction Z and the groove width direction Y, and the normal line a _x1 of the steel plate surface 5a and the laser beam L ₁ are relative to the moving steel plate surface 5a. _The laser beam L1 is irradiated at _a predetermined angle θ1 from the normal line a _x1 of the steel plate surface 5a in the plane including the optical axis of. As a result, in the present embodiment, the linear groove 8 is machined on the steel plate surface 5a along the X direction in which the steel plate 5 moves. In addition, on the steel plate surface 5a, for example, a plurality of grooves 8 may be formed so as to be arranged at predetermined intervals in the groove width direction Y and run in parallel in the groove extending direction X.

Here, FIG. 3 shows a cross section in the groove width direction in AA ′ extending in the groove width direction Y orthogonal to the groove extension direction X and the normal direction Z in FIG. 2. As shown in FIG. 3A, when the laser beam L1 begins to be irradiated to the steel sheet surface 5a at _an irradiation angle θ ₁ from the normal line _{a x 1} , the laser beam L1 is irradiated at the beginning of the irradiation of the laser beam L1. At the groove processing position 10 to be formed, a molten portion 10a in which the steel plate 5 is melted is formed.

Further, when the molten portion 10a is irradiated with the laser beam L1 while the steel plate ₅ is moving, as shown in FIG. 3B, during the irradiation of the laser beam _L1 , the laser beam L1 is inside the fused portion _10a . A keyhole KH of a columnar cavity inclined diagonally along the optical axis direction is temporarily formed. Such a keyhole KH is formed by the heat of the laser beam L ₁ and the pressure of the metal vapor gas. Then, for example, at the tip portion 10b on the back side of the keyhole KH, the non _- incident side portion of the laser beam L1 in which the amount of the melt is small and the thickness of the melt is thin bursts due to the pressure of the metal steam gas or the like, and the keyhole is formed. The metal vapor gas in the KH escapes from the non _- incident side of the laser beam L1 to the outside. As a result, it is considered that the groove 8 is likely to be formed on the non-incident side of the laser beam L1 in the molten portion 10a.

After that, when the steel plate ₅ moves and the laser beam L1 finishes irradiating, the groove 8 is formed on the steel plate surface 5a. Here, FIG. 4 shows a cross section in the groove width direction at BB'in FIG. 2. FIG. 4 is a cross-sectional view in the groove width direction after the laser beam L1 has finished irradiating and the groove ₈ has been machined, and is an enlarged view of the periphery of the groove 8. In this case, a groove 8 having a concave cross section is formed on the surface 5a of the steel plate, and a melt-solidified portion 11 in which the melted portion 10a is solidified is formed inside the steel plate 5 around the groove 8. Here, since the keyhole KH was formed during the processing of the groove 8, as shown in FIG. 4, the melt solidification portion 11 is not on the incident _side of the laser beam L1 when the groove 8 is used as a reference. It is unevenly distributed on the incident side, and a melt-solidified convex portion 11a bulging from the steel plate surface 5a is formed on the incident _side of the laser beam L1.

In defining the groove 8, the straight line extending along the steel plate surface 5a when the groove ₈ is viewed in the cross section in the groove width direction is defined as the surface reference line BL1. The surface reference line BL ₁ can be obtained, for example, by obtaining the surface roughness curve of the steel sheet surface 5a and averaging the surface roughness curves.

As shown in FIG. 4, the depth d of the groove 8 machined on the steel plate surface 5a is a surface reference line when the groove 8 is viewed in a cross section in the groove width direction orthogonal to the groove extending direction X and the normal direction Z. It is the distance from BL ₁ to the deepest portion 8c of the groove 8, and is preferably 10.5 μm or more and 50 μm or less.

Further, when the groove 8 is viewed in the cross section in the groove width direction, the distance between the groove opening end portions 9a and 9b facing the groove ₈ is defined as the groove opening end width W1. Further, when the groove 8 is viewed in the cross section in the groove width direction, _a straight line passing through the center O of the groove opening end width W1 and parallel to the normal direction Z is defined as the groove opening center line BL ₂ .

The inner surface of the groove 8 formed in the steel plate 5 is located on the incident side (right side in FIG. ₄ ) of the laser beam L1 along the groove extending direction X with the groove opening center line BL ₂ as a boundary. It can be divided into one groove surface 8a and a second groove surface 8b on the non _- incident side of the laser beam L1. In the groove 8 shown in FIG. 4, the deepest portion 8c is formed on the second groove surface 8b on the non-incident side (left side in FIG. 4) of the laser light L ₁ , and the incident side of the laser light L ₁ is formed. The first groove surface 8a in the above is formed in a wall shape.

Further, the melt-solidified portion 11 has a melt-solidified convex portion 11a, a first melt-solidified portion 11b, and a second along the groove extending direction X with the surface reference line BL ₁ and the groove opening center line BL ₂ as boundaries. It can be divided into a melt solidification section 11c.

The groove opening center line BL ₂ divides the melt solidification portion 11 inside the steel plate 5 into a first melt solidification portion 11b and a second melt solidification portion 11c, and the surface reference line BL ₁ is inside the steel plate 5. A certain first melt-solidified portion 11b and a melt-solidified convex portion 11a bulging from the steel plate surface 5a are separated.

In this case, the first melt-solidified portion 11b is a melt-solidified portion 11 in the steel plate 5 formed around the first groove surface 8a on the incident side of the laser beam L ₁ , and is the surface reference line BL ₁ and the groove opening. The melt solidification portion 11 surrounded by the center line BL ₂ is shown. On the other hand, the second melt-solidified portion 11c is a melt-solidified portion 11 in the steel plate 5 formed around the second groove surface 8b on the non _- incident side of the laser beam L1 and is surrounded by the groove opening center line BL ₂ . The melt-solidified portion 11 that has been melted is shown. Further, the melt-solidified convex portion 11a shows a melt-solidified portion 11 that bulges upward from the steel plate surface 5a with the surface reference line BL ₁ as a boundary.

When the groove 8 is viewed in the groove width direction cross section along the groove extending direction X, the first melt-solidified portion 11b is formed larger than the second melt-solidified portion 11c. Thereby, even after the groove 8 is machined, the incident side and the non-incident side of the laser beam L1 at the time of manufacturing can be estimated by observing the cross section in the groove width direction.

Here, when viewing the groove 8 in the cross section in the groove width direction, for example, the steel plate 5 in which the groove 8 is machined is cross-sectionally polished along the groove width direction Y by, for example, mechanical polishing, and then with nital or picric acid. By corrosion treatment, a cross section in the groove width direction is obtained. Then, the obtained cross section in the groove width direction is observed using SEM, and the melt-solidified portion 11 of the steel sheet ₅ and the unmelted portion not irradiated with the laser beam L1 are distinguished by image processing.

Here, the melt-solidified portion 11 and the unmelted portion of the steel plate 5 can be distinguished from each other by the continuity of the metal structure.

Next, an image analysis is performed on the image of the cross section in the groove width direction obtained by SEM, and the surface reference line BL ₁ and the groove opening center line BL ₂ are obtained from the cross-sectional shape of the groove 8 in the image and the cross-sectional shape of the steel plate surface 5a. Ask for. Then, by image analysis, the melt solidification portion 11 in the image is formed by the melt solidification convex portion 11a, the first melt solidification portion 11b, and the second melt solidification portion 11c with the surface reference line BL ₁ and the groove opening center line BL ₂ as boundaries. It is divided into.

As a result, the first melt-solidified portion 11b in the steel plate 5 surrounded by the surface reference line BL ₁ and the groove opening center line BL ₂ and the second melt-solidified portion in the steel plate 5 surrounded by the groove opening center line BL ₂ The area with 11c can be measured. In this way, it can be confirmed that the first melt-solidified portion 11b is formed larger than the second melt-solidified portion 11c inside the steel sheet 5.

The melt-solidified convex portion 11a bulging from the steel plate surface 5a may be removed by a flattening treatment for flattening the steel plate surface 5a by polishing or the like (flattening step). As a result, it is possible to obtain a steel plate 5 in which only the groove 8 is processed on the flattened steel plate surface 5a.

<Verification test>
Next, a verification test using the groove processing apparatus 1 will be described. In the verification test here, as a sample for processing the groove, a rectangular steel plate 5 made of rolled steel for general structure (SS400), having a thickness of 4 mm, a length of 100 mm, and a width of 50 mm was prepared. In this verification test, first, the laser output (Power) is 175 W, the irradiation angle θ ₁ of the laser beam L ₁ is 45 degrees, and the scanning speeds are 1.0 m / s and 1.5 m / s. Grooves were machined on each steel plate surface 5a at a rate of 2.0 m / s.

Then, when the formation state of the groove 8 on the steel sheet surface 5a was observed with an optical microscope, the results shown in FIGS. 5A, 5B and 5C were obtained. In FIGS. 5A, 5B and 5C, the right side of the paper surface is the incident side of the laser beam L ₁ , and the left side of the paper surface is the non-incident side of the laser light L ₁ . As shown in FIGS. 5A, 5B and 5C, it is confirmed that the concave region L is linearly formed on the non _- incident side of the laser beam L1 and the groove 8 is formed on the steel plate surface 5a. did it. However, in FIG. 5A where the scanning speed is 1.0 m / s, the groove 8 may be shallower than in FIGS. 5B and 5C where the scanning speed is 1.5 m / s or more due to the degree of color shading in the image. It could be confirmed.

Further, as shown in FIGS. 5A, 5B and 5C, a linear convex region H is formed along the concave region L on the incident side of the laser beam L ₁ , and a melt solidification convex portion 11a is formed. I was able to confirm that. However, in FIG. 5A where the scanning speed was 1.0 m / s, it was also confirmed that the convex region H was lower than in FIGS. 5B and 5C where the scanning speed was 1.5 m / s or more.

Next, each of the steel plates 5 shown in FIGS. 5A, 5B and 5C is cross-sectionally polished along the groove width direction Y by a rotary grinding machine and corroded with picric acid to obtain a cross-section in the groove width direction. rice field. Then, when the cross section in each groove width direction was photographed by SEM, the images as shown in FIGS. 6A, 6B and 6C were obtained. FIG. 6A is a groove width direction cross section at a scanning speed (denoted as Velocity) of 1.0 m / s, and FIG. 6B is a groove width direction cross section at a scanning speed (denoted as Velocity) of 1.5 m / s. Yes, FIG. 6C is a cross section in the groove width direction at a scanning speed (denoted as Velocity) of 2.0 m / s.

In FIG. 6A, on the incident side of the laser beam L1, _a melt-solidified convex portion 11a that swells slightly convexly adjacent to the groove 8 can be confirmed, but the depth d of the groove 8 is as shallow as 10.4 μm. It was confirmed that a significant groove depth could not be obtained. Further, in FIG. 6B, the depth d of the groove 8 is 13.0 μm, a significant groove depth of 10.5 μm or more is obtained, and the melting is higher than that of the steel plate surface 5a on the incident _side of the laser beam L1. The solidified convex portion 11a was confirmed. Also in FIG. 6C, the depth d of the groove 8 is 20.2 μm, a significant groove depth of 10.5 μm or more can be obtained, and further, the melt solidification convexity higher than that of the steel plate surface 5a on the incident _side of the laser beam L1. Part 11a was confirmed.

In FIGS. 6B and 6C, the melt-solidified portion 11 and the unmelted portion could be visually distinguished from each other by using the difference in metal structure as a guide. Further, for each of the images of FIGS. 6B and 6C, the surface reference line BL ₁ and the groove opening center line BL ₂ were obtained, respectively, and the areas of the first melt-solidified portion 11b and the second melt-solidified portion 11c were compared. It was confirmed that the first melt-solidified portion 11b was larger than the second melt-solidified portion 11c.

Next, the laser output was changed to 200 W, and a groove was formed on the steel plate surface 5a. The conditions other than the laser output are the same as the above verification test (the irradiation angle θ ₁ of the laser beam L1 is 45 degrees, and the scanning speed is 1.0 m / s, 1.5 m / s, 2.0 m. Grooves were formed on the surface 5a of each steel plate instead of / s.

Then, when the formation state of the groove 8 on the steel sheet surface 5a was observed with an optical microscope, the results shown in FIGS. 7A, 7B and 7C were obtained. In FIGS. 7A, 7B and 7C, the right side of the paper surface is the incident side of the laser beam L ₁ , and the left side of the paper surface is the non-incident side of the laser light L ₁ . As shown in FIGS. 7A, 7B and 7C, a concave region L corresponding to the groove 8 is linearly formed on the non-incident side of the laser beam L ₁ and is formed on the incident side of the laser beam L ₁ . It was confirmed that the convex region H corresponding to the melt-solidified convex portion 11a was formed in a linear shape along the concave region L. However, in FIG. 7A where the scanning speed is 1.0 m / s, the concave region corresponding to the groove is larger than those in FIGS. 7B and 7C where the scanning speed is 1.5 m / s or more due to the degree of color shading in the image. It was confirmed that L became shallow and the convex region H became low.

Next, each of the steel plates 5 shown in FIGS. 7A, 7B and 7C is cross-sectionally polished along the groove width direction Y by a rotary grinding machine and corroded with picric acid to obtain a cross-section in the groove width direction. rice field. Then, when the cross section in each groove width direction was photographed by SEM, the images as shown in FIGS. 8A, 8B and 8C were obtained. FIG. 8A is a groove width direction cross section at a scanning speed (denoted as Velocity) of 1.0 m / s, and FIG. 8B is a groove width direction cross section at a scanning speed (denoted as Velocity) of 1.5 m / s. Yes, FIG. 8C is a cross section in the groove width direction at a scanning speed (denoted as Velocity) of 2.0 m / s.

In FIG. 8A, a melt-solidified convex portion 11a that swells slightly convexly in a region adjacent to the groove 8 on the incident _side of the laser beam L1 can be confirmed, but the depth d of the groove 8 is as shallow as 7.8 μm. It was confirmed that a significant groove depth could not be obtained. Further, in FIG. 8B, the depth d of the groove 8 is 22.2 μm, a significant groove depth of 10.5 μm or more is obtained, and the melting is higher than that of the steel plate surface 5a on the incident _side of the laser beam L1. The solidified convex portion 11a was confirmed. In FIG. 8C, the depth d of the groove 8 is 26.1 μm, a significant groove depth of 10.5 μm or more is obtained, and the melt solidification convexity higher than that of the steel plate surface 5a on the incident _side of the laser beam L1. Part 11a was confirmed.

In FIGS. 8B and 8C, similarly to the above verification test, the melt-solidified portion 11 and the unmelted portion could be visually distinguished by using the difference in metal structure as a guide. Further, for each of the images of FIGS. 8B and 8C, the surface reference line BL ₁ and the groove opening center line BL ₂ were obtained, and the areas of the first melt-solidified portion 11b and the second melt-solidified portion 11c were compared. Similar to the above verification test, it was confirmed that the first melt-solidified portion 11b was larger than the second melt-solidified portion 11c.

As described above, it has been found that when the laser outputs are low outputs of 175 W and 200 W, when the scanning speed is increased, the melt-solidified convex portion 11a becomes larger and the height protruding from the steel plate surface 5a becomes higher. Further, it was confirmed that the groove 8 became deeper as the melt-solidified convex portion 11a became larger. From the results of such a verification test, it was confirmed that it is desirable to set the scanning speed to 1.5 m / s or more when processing the deep groove 8.

<Action and effect>
In the above configuration, in the groove processing apparatus 1, the steel plate 5 is relatively moved at 1.5 m / s or more and 100 m / s or less with respect to the laser light source 2 (movement step), and the normal line a _x1 of the steel plate surface 5a. In a plane including the laser beam L ₁ and the laser beam L 1, the laser beam L ₁ is tilted by a predetermined angle θ ₁ from the normal line a _x 1 to irradiate the steel plate 5 (irradiation step).

At this time, in the grooving apparatus 1, the laser output of the laser light source 2 with respect to the grooving position of the steel plate 5 is set to 100 W or more and 1000 W or less (laser output control step).

As a result, the groove processing apparatus 1 can process the groove 8 having a depth d of 10.5 μm or more and 50 μm or less on the steel plate surface 5a. Further, in the groove 8 processed in this way, when the groove 8 is viewed in the groove width direction cross section, the laser beam L1 is incident along the groove extending direction X with the groove opening center line BL ₂ as _a boundary. The first melt-solidified portion 11b on the side and the second melt-solidified portion 11c on the non-incident side of the laser beam L1 have an asymmetric shape, and the _first melt-solidified portion 11b is formed larger than the second melt-solidified portion 11c. can.

As described above, in the groove processing apparatus 1, the groove 8 having a desired shape can be machined on the steel plate surface 5a by controlling the flow of the molten metal in the molten portion 10a while achieving a low output laser output, and an assist gas or a high output laser that blows off the melt. A groove 8 having a desired shape can be machined without using a light source. In addition, the cost can be reduced because the assist gas for blowing off the melt and the high-power laser light source are not required.

(2) Second Embodiment <Structure of Grooving Equipment According to the Second Embodiment>
Next, the groove processing apparatus of the second embodiment will be described below. As shown in FIG. 9, the grooving apparatus 21 is different from the _first embodiment described above in that the steel plate 5 is tilted and the tilted steel plate surface 5a is irradiated with the laser beam L1 from the vertical direction. It's different.

As a result, in the groove processing apparatus 21, the laser beam L1 is directed at _a predetermined angle from the normal line a _x1 in the plane including the normal line a _x1 of the steel plate surface 5a and the laser beam L1 as in the _first embodiment. θ ₁ is tilted. In this case, the groove processing device 21 processes the groove on the steel plate surface 5a by irradiating the inclined steel plate surface 5a with the laser beam L1 from the vertical direction while moving the steel plate ₅ in the X direction.

Even in the case of this embodiment, the angle (irradiation angle) θ ₁ formed by the normal line _{a x1} and the laser light L1 in the plane including the normal line _{a x1} of the steel plate surface 5a and the laser light L1 is determined. It is desirable that the temperature is set to 20 degrees or more and 80 degrees or less, and more preferably, it is more than 45 degrees and less than 75 degrees.

Also in this embodiment, as shown in FIG. 9, the laser beam L ₁ is tilted at an irradiation angle θ ₁ with respect to the normal line a _x 1 in the plane formed by the groove width direction Y and the normal direction Z. The present invention is not limited to this. In the present invention, the irradiation angle θ ₁ of the laser beam L ₁ may be defined with respect to the normal line a _x 1 in the plane formed by the normal line a _x 1 of the steel plate surface 5a and the laser beam L ₁ , for example, a groove. Outside the plane formed by the width direction Y and the normal direction Z, the laser beam L1 may be tilted by _{an irradiation angle θ 1 with} respect to the normal a _x1 in the plane.

In this case, in the groove processing device 21, the laser light source 2 is fixed at _a predetermined position so that the laser beam L1 is irradiated along the vertical direction. The grooving device 21 includes a moving mechanism 22, and the moving mechanism 22 tilts the steel plate 5 and moves the tilted steel plate 5 along the X direction.

The moving mechanism 22 includes a base 23, a slide base 24, an inclined support portion 25, and a movement control unit 26, and the slide base 24 is movably provided on the base 23. The slide table 24 is controlled by the movement control unit 26, and moves along the X direction at a constant speed based on the control signal from the movement control unit 26.

The inclined support portion 25 is installed on the slide table 24 and moves along the X direction together with the slide table 24. The inclined support portion 25 has an inclined surface, and the steel plate 5 is inclined by installing the steel plate 5 on the inclined surface. In this case, the angle θ ₂ formed by the horizontal line a _x 3 and the inclined surface is selected for the inclined support portion 25, and by adjusting the angle θ ₂ , the irradiation angle θ ₁ of the laser beam L ₁ with respect to the steel plate surface 5 a can be obtained. Set.

In the case of the present embodiment, since θ ₂ is the angle formed by the horizontal line a _x3 and the inclined surface, the normal line a _x1 of the inclined steel plate surface 5a and the laser beam L1 irradiated in the vertical direction form _each other. The angle θ ₁ is the same as the angle θ ₂ of the inclined support portion 25.

As described above, in the groove processing apparatus 21, unlike the first embodiment, the angle θ ₂ of the steel plate 5 is changed by the inclined support portion 25 without changing the irradiation direction of the laser beam L ₁ , so that the steel plate surface 5a It is possible to irradiate the laser beam L ₁ at a predetermined angle θ ₁ .

At this time, since each condition such as the laser output of the laser light source 2 and the scanning speed of the steel plate 5 with respect to the laser light source 2 is the same as that of the first embodiment described above, the description thereof is omitted here.

<Regarding the groove machined by the groove processing apparatus of the present invention>
Next, the groove 8 machined by the groove processing apparatus 21 of the second embodiment according to the present invention will be described in detail. Here, as shown in FIGS. 10A and 10B, the steel plate 5 is inclined at an angle θ ₂ by the inclined support portion 25, and is 1.5 m / s or more and 100 m / s or less, more preferably 2 m / s or more. While being moved in the X direction at a scanning speed of 90 m / s or _less , the inclined steel plate surface 5a is irradiated with the laser beam L1 from the vertical direction.

_At this time, in FIG. 10A, the cross _- section S1 in the groove width direction of the groove processing position irradiated with the laser beam L1 is shown in FIGS. 11A and 11B. As shown in FIG. 11A, when the laser beam L1 starts to irradiate the inclined steel sheet surface 5a from the vertical direction, the steel sheet ₅ is melted and melted at the grooving position ₁₀ at the beginning of the irradiation of the laser beam L1. The portion 10a is formed.

Further, when the molten portion 10a is irradiated with the laser beam L1 while the steel plate ₅ is moving, as shown in FIG. 11B, during the irradiation of the laser beam _L1 , the laser beam L1 is inside the fused portion _10a . A keyhole KH of a columnar cavity inclined diagonally along the optical axis direction is temporarily formed. Such a keyhole KH is the same as that of the first embodiment, and is formed even when the steel plate 5 is tilted. Then, for example, at the tip portion 10b on the back side of the keyhole KH, the non _- incident side portion of the laser beam L1 in which the amount of the melt is small and the thickness of the melt is thin bursts due to the pressure of the metal steam gas or the like, and the keyhole is formed. The metal vapor gas in the KH escapes from the non _- incident side of the laser beam L1 to the outside. Therefore, even in the second embodiment, it is considered that the groove 8 is likely to be formed on the non-incident side of the laser beam L1 in the molten portion 10a.

After that, when the steel plate ₅ moves and the laser beam L1 finishes irradiating, the groove 8 is formed on the steel plate surface 5a.

FIG. 12 shows _a cross section S1 in the groove width direction of _a portion where the laser beam L1 has finished irradiating and the groove 8 has been formed in FIG. 10B. In this case, a groove 8 having a concave cross section is formed on the surface 5a of the steel plate, and a melt-solidified portion 11 in which the melted portion 10a is solidified is formed inside the steel plate 5 around the groove 8. As shown in FIG. 12, the melt solidification portion 11 is unevenly distributed on the incident side and the non _- incident side of the laser beam L1 due to the formation of the keyhole KH during the processing of the groove ₈ , and the laser beam L1 is distributed. A melt-solidified convex portion 11a bulging from the steel plate surface 5a is formed on the incident side of the steel plate.

The groove 8 machined on the steel plate surface 5a by the groove processing apparatus 21 according to the second embodiment has a configuration as shown in FIG. 4 as in the first embodiment described above. In this case, when the groove 8 is viewed in a cross section in the groove width direction orthogonal to the groove extending direction X and the normal direction Z, it is desirable that the depth d of the groove 8 is 10.5 μm or more and 50 μm or less.

Further, also in this second embodiment, as shown in FIG. 4, when the groove 8 is viewed in the cross section in the groove width direction, the groove surface of the groove 8 formed in the steel plate 5 is in the groove extending direction X. It can be divided into a _first groove surface 8a on the incident side of the laser beam L1 and a _second groove surface 8b on the non-incident side of the laser beam L1 with the groove opening center line BL ₂ as a boundary. can.

The melt-solidified portion 11 has a melt-solidified convex portion 11a, a first melt-solidified portion 11b, and a second melt-solidified portion along the groove extending direction X with the surface reference line BL ₁ and the groove opening center line BL ₂ as boundaries. It can be divided into 11c. The groove opening center line BL ₂ divides the melt solidification portion 11 inside the steel plate 5 into a first melt solidification portion 11b and a second melt solidification portion 11c, and the surface reference line BL ₁ is inside the steel plate 5. A certain first melt-solidified portion 11b and a melt-solidified convex portion 11a bulging from the steel plate surface 5a are separated.

Further, also in the second embodiment, when the groove 8 is viewed in the groove width direction cross section along the groove extension direction X, the laser beam is emitted along the groove extension direction X with the groove opening center line BL ₂ as a boundary. The first melt-solidified portion 11b on the incident side of L ₁ and the second melt-solidified portion 11c on the non-incident side of the laser beam L ₁ have an asymmetric shape, and the first melt-solidified portion 11b becomes the second melt-solidified portion 11c. Larger grooves 8 can be machined.

<Verification test>
Next, a verification test using the groove processing apparatus 21 shown in FIG. 9 will be described. As a sample for processing the groove, a rectangular steel plate 5 made of rolled steel for general structure (SS400), having a thickness of 4 mm, a length of 100 mm, and a width of 50 mm was prepared. In the _{first verification test, the laser output (Power) was 200 W, the irradiation angle θ 1 of} the laser beam L1 due to sample tilt was 40 degrees, the scanning speed was 2.0 m / s, and no shield gas was used. A groove 8 was formed on the surface 5a of the steel plate.

When the formation state of the groove 8 on the steel sheet surface 5a was observed by SEM, the result as shown in FIG. 13 was obtained. As shown in FIG. 13, a linear groove 8 can be machined along the direction in which the laser beam L1 is scanned, and the melt _- solidified convex portion 11a _runs parallel to the groove 8 on the incident side of the laser beam L1. Was confirmed to be formed.

Next, the laser output is 200 W, the irradiation angle θ ₁ of the laser beam L ₁ due to the sample tilt is 40 degrees, the scanning speed is 2.0 m / s, the shield gas conditions are changed, and grooves are formed on each steel plate surface 5a. processed. Then, there are grooves when the shield gas is not used, when the flow rate of the shield gas is 10 L / s and the gas pressure is 0.1 MPa, and when the flow rate of the shield gas is 20 L / s and the gas pressure is 1.0 MPa. The formation state of was confirmed.

Each of the obtained steel sheets 5 was subjected to cross-section polishing along the groove width direction Y with a rotary grinding machine and corroded with picric acid to obtain a cross-section in the groove width direction. Then, when the cross section in each groove width direction was photographed by SEM, the images as shown in FIGS. 14A, 14B and 14C were obtained. In FIGS. 14A, 14B and 14C, the vertical direction of the inclined steel plate 5 is indicated by "Slope", the upper side is indicated by "U", and the lower side is indicated by "L".

When the shield gas is not used, as shown in FIG. 14A, a melt-solidified convex portion 11a bulging from the steel plate surface 5a is formed on the incident _side of the laser beam L1, and the groove opening end width is wide and deep. It was confirmed that the groove 8 having a depth of 22.6 μm can be machined.

When the shield gas has a flow rate of 10 L / s and a gas pressure of 0.1 MPa, as shown in FIG. 14B, a melt-solidified convex portion 11a bulging from the steel plate surface 5a is formed on the incident _side of the laser beam L1. It was confirmed that it would be done. Further, as compared with FIG. 14A, it was confirmed that the groove 8 having a depth of 23.9 μm could be machined, but the groove opening end width of the groove 8 became narrower.

On the other hand, when the shield gas has a flow rate of 20 L / s and a gas pressure of 1.0 MPa, a concave region having a depth of 26.9 μm is formed as shown in FIG. 14C, but on the incident _side of the laser beam L1. It was confirmed that the formed melt-solidified convex portion 11a collapsed to the non-incident side, the groove was closed by the melt-solidified convex portion 11a, and it was difficult to process the groove. Therefore, it is desirable that the shield gas has a flow rate of less than 20 L / s and a gas pressure of less than 1.0 MPa, and more preferably, the flow rate is 10 L / s or less, the gas pressure is 0.1 MPa or less, and the shield gas is not used. It was confirmed that it was desirable. The desirable conditions for such a shield gas are the same in the above-mentioned first embodiment.

Further, in FIGS. 14A and 14B, the melt-solidified portion 11 and the unmelted portion could be visually distinguished from each other by using the difference in metal structure as a guide. With respect to FIGS. 14A and 14B, the surface reference line BL ₁ and the groove opening center line BL ₂ were obtained, and the areas of the first melt-solidified portion 11b and the second melt-solidified portion 11c were compared. It was confirmed that the first melt-solidified portion 11b was larger than the 11c.

Next, the laser output (Power) is 200 W, the irradiation angle θ ₁ of the laser beam L ₁ due to the sample tilt is 45 degrees, and the scanning speeds are 1.0 m / s, 1.5 m / s, 2. Grooves were machined on each steel plate surface 5a at 0 m / s.

Each of the obtained steel sheets 5 was subjected to cross-section polishing along the groove width direction Y with a rotary grinding machine and corroded with picric acid to obtain a cross-section in the groove width direction. Then, when the cross section in each groove width direction was photographed by SEM, the images as shown in FIGS. 15A, 15B and 15C were obtained. In FIGS. 15A, 15B and 15C, the vertical direction of the inclined steel plate 5 is indicated by "Slope", the upper side is indicated by "U", and the lower side is indicated by "L".

When the scanning speed was 1.0 m / s, as shown in FIG. 15A, a melt-solidified convex portion 11a slightly bulging from the steel plate surface 5a was formed on the incident _side of the laser beam L1. It was confirmed that only a shallow groove 8 having a depth of less than 10.5 μm can be machined.

On the other hand, when the scanning speeds are 1.5 m / s and 2.0 m / s, as shown in FIGS. 15B and 15C, melt solidification swelling from the steel plate surface 5a on the incident _side of the laser beam L1. It was confirmed that the convex portion 11a was formed, the groove opening end width was wide, and the deep grooves 8 having depths of 24.1 μm and 26.2 μm and 10.5 μm or more could be machined, respectively. From the above, it was confirmed that by setting the scanning speed to more than 1.5 m / s, the groove 8 having a wide groove opening end width and a deeper groove can be machined.

Also in FIGS. 15B and 15C, the melt-solidified portion 11 and the unmelted portion could be visually distinguished from each other by using the difference in metal structure as a guide. For FIGS. 15B and 15C, the surface reference line BL ₁ and the groove opening center line BL ₂ were obtained, and the areas of the first melt-solidified portion 11b and the second melt-solidified portion 11c were compared. It was confirmed that the first melt-solidified portion 11b was larger than the 11c.

Next, the laser output was reduced to 150 W, and a groove was formed on the steel plate surface 5a. The conditions other than the laser output are the same as in the above verification test (irradiation angle θ ₁ of the laser beam L1 due to sample tilt is 40 degrees), and the scanning speed is 1.0 m / s and 1.5 m / s. , 2.0 m / s, and grooves were machined on each steel plate surface 5a.

Each steel sheet 5 was cross-sectionally polished along the groove width direction Y with a rotary grinding machine and corroded with picric acid to obtain a cross-section in the groove width direction. Then, when the cross section in each groove width direction was photographed by SEM, the images as shown in FIGS. 16A, 16B and 16C were obtained. In FIGS. 16A, 16B and 16C, the vertical direction of the inclined steel plate 5 is indicated by "Slope", the upper side is indicated by "U", and the lower side is indicated by "L".

When the scanning speed was 1.0 m / s, as shown in FIG. 16A, a melt-solidified convex portion 11a slightly bulging from the steel plate surface 5a was formed on the incident _side of the laser beam L1. It was confirmed that only a shallow groove 8 having a depth of less than 10.5 μm can be machined.

On the other hand, when the scanning speed is 1.5 m / s, when the laser output is reduced to 150 W, the groove 8 becomes shallower than the depth of the groove 8 (more than 20 μm shown in FIG. 15B) when the laser output is 200 W. However, it was confirmed that the groove 8 having a width of 10.7 μm and a depth of 10.5 μm or more can be machined.

Further, when the scanning speed is 2.0 m / s, as shown in FIG. 16C, even if the laser output is reduced to 150 W, the groove opening end width is wide and the depth is as deep as 26.9 μm. It was confirmed that it can be processed. From the above, it was confirmed that even when the laser output is reduced to 150 W, the groove 8 having a wide groove opening end width and a deep groove 8 can be machined by setting the scanning speed to more than 1.5 m / s. Further, it was confirmed that it is desirable to set the scanning speed to 2.0 m / s or more when processing a deeper groove 8 when the laser output is reduced to 150 W.

Also in FIGS. 16B and 16C, the melt-solidified portion 11 and the unmelted portion could be visually distinguished from each other by using the difference in metal structure as a guide. For FIGS. 16B and 16C, the surface reference line BL ₁ and the groove opening center line BL ₂ were obtained, and the areas of the first melt-solidified portion 11b and the second melt-solidified portion 11c were compared. It was confirmed that the first melt-solidified portion 11b was larger than the 11c.

<Action and effect>
In the above configuration, in the groove processing apparatus 21, the steel plate 5 is tilted so that the laser light L1 is predetermined from the normal line _{a x1} in the plane including the normal line _{a x1} of the steel plate surface 5a and the laser light L1. The angle θ was tilted by ₁ so that the steel plate 5 was irradiated with the laser beam.

Even in such a groove processing device 1, by setting the laser output of the laser light source 2 that emits laser light to 100 W or more and 1000 W or less, the groove 8 having a depth d of 10.5 μm or more and 50 μm or less is processed into the steel plate surface 5a. can.

Further, in the groove 8 processed in this way, when the groove 8 is viewed in the groove width direction cross section, the laser beam L1 is incident along the groove extending direction X with the groove opening center line BL ₂ as _a boundary. The first melt-solidified portion 11b on the side and the second melt-solidified portion 11c on the non-incident side of the laser beam L1 have an asymmetric shape, and the _first melt-solidified portion 11b is formed larger than the second melt-solidified portion 11c. can.

As described above, even in the groove processing device 21, the groove 8 having a desired shape can be machined on the steel plate surface 5a by controlling the flow of the molten metal in the molten portion 10a while achieving a low output laser output, and an assist gas or a high output laser that blows off the melt can be formed. A groove 8 having a desired shape can be machined without using a light source. In addition, the cost can be reduced because the assist gas for blowing off the melt and the high-power laser light source are not required.

(3) Other Embodiments The present invention is not limited to this embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, as the steel plate for processing the groove, various other steel plate original plates such as a heat-dissipating steel plate, a laminated steel plate, and an electromagnetic steel plate may be applied.

Further, in the above-described embodiment, as the moving mechanism for moving the steel plate relative to the laser beam, the moving mechanisms 7 and 22 for moving the steel plate 5 with respect to the fixed laser light source 2 are applied. Is not limited to this. For example, a moving mechanism for moving the laser light source 2 may be applied to the fixed steel plate 5.

Further, in the above-described embodiment, the case where the steel plate 5 is linearly moved with respect to the laser beam L1 to form _a groove 8 linearly extending on the steel plate surface 5a has been described. Not limited to this, the moving direction of the laser light source 2 or the steel plate 5 may be controlled to machine a curved groove such as an arch.

1, 21 Grooving device 2 Laser light source 5 Steel plate 5a Steel plate surface 6 Laser output control unit 7, 22 Movement mechanism 11a Melt solidification convex part 11b First melt solidification part 11c Second melt solidification part

Claims (5)

In the grooving method for grooving the surface of a steel sheet with laser light,
Irradiation of the laser beam emitted from the laser light source to irradiate the steel plate surface at an angle of 20 degrees or more and 80 degrees or less from the normal line in a plane containing the normal line of the steel plate surface and the laser beam. Process and
A moving step of moving the steel sheet relative to the laser light source at 1.5 m / s or more and 100 m / s or less.
A laser output control step of setting the laser output of the laser light source to 100 W or more and 1000 W or less,
Equipped with
The steel sheet is melted and processed by the laser beam to make the groove depth 10.5 μm or more and 50 μm or less.
When the groove is viewed in the groove width direction cross section orthogonal to the groove extension direction, the center of the groove opening end width is defined as the groove opening center line, and the melt-solidified portion formed around the groove inside the steel sheet. Was divided into a first melt-solidified portion and a second melt-solidified portion with the groove opening center line as a boundary.
Along the groove extending direction, with the groove opening center line as a boundary, the first melt-solidified portion on the incident side of the laser beam and the second melt-solidified portion on the non-incident side of the laser light are formed. A grooving method having an asymmetrical shape and forming the first melt-solidified portion larger than the second melt-solidified portion. In the irradiation step,
The groove processing method according to claim 1 , wherein a melt-solidified convex portion bulging from the surface of the steel sheet is formed on the incident side of the laser beam by irradiation with the laser beam. The groove processing method according to claim 2 , further comprising a flattening step of removing the melt-solidified convex portion and flattening the surface of the steel sheet. In a grooving device that groovs the surface of a steel sheet with laser light
A laser light source that irradiates the surface of the steel sheet with the laser light at an angle of 20 degrees or more and 80 degrees or less from the normal in a plane containing the normal of the surface of the steel sheet and the laser light.
A moving mechanism that moves the steel sheet relative to the laser light source at 1.5 m / s or more and 100 m / s or less.
A laser output control unit that sets the laser output of the laser light source to 100 W or more and 1000 W or less.
Equipped with
The steel sheet is melted and processed by the laser beam to make the groove depth 10.5 μm or more and 50 μm or less.
When the groove is viewed in the groove width direction cross section orthogonal to the groove extension direction, the center of the groove opening end width is defined as the groove opening center line, and the melt-solidified portion formed around the groove inside the steel sheet. Was divided into a first melt-solidified portion and a second melt-solidified portion with the groove opening center line as a boundary.
Along the groove extending direction, with the groove opening center line as a boundary, the first melt-solidified portion on the incident side of the laser beam and the second melt-solidified portion on the non-incident side of the laser light are formed. A grooving device having an asymmetrical shape and forming the first melt-solidified portion larger than the second melt-solidified portion. In a steel sheet with grooves on the surface of the steel sheet
The depth of the groove is 10.5 μm or more and 50 μm or less.
When the groove is viewed in the groove width direction cross section orthogonal to the groove extension direction, the center of the groove opening end width is defined as the groove opening center line, and the melt-solidified portion formed around the groove inside the steel sheet. Was divided into a first melt-solidified portion and a second melt-solidified portion with the groove opening center line as a boundary.
Along the groove extending direction, the first melt-solidified portion and the second melt-solidified portion have an asymmetric shape with the groove opening center line as a boundary, and the first melt-solidified portion is from the second melt-solidified portion. A steel plate that is also large.

Images