阅读说明：本技术 激光加工机及激光加工方法 (Laser processing machine and laser processing method ) 是由 杉山明彦 于 2019-10-04 设计创作，主要内容包括：电流扫描仪单元(32)在一边使加工头相对于金属板(W)相对移动一边对金属板(W)照射激光束来切断金属板(W)时,使激光束振动。集光镜驱动部(340)使向金属板(W)照射的激光束的焦点在与金属板(W)的表面正交的正交方向上移动。焦点位置控制部(502)为了使激光束的焦点位于正交方向上的预定位置而控制集光镜驱动部(340)。电流控制部(501)根据焦点的正交方向的位置控制电流扫描仪单元(32),以改变使激光束振动的振幅。(The current scanner unit (32) vibrates the laser beam when irradiating the metal plate (W) with the laser beam while relatively moving the processing head with respect to the metal plate (W) to cut the metal plate (W). A condenser drive unit (340) moves the focal point of a laser beam applied to the metal plate (W) in the orthogonal direction orthogonal to the surface of the metal plate (W). A focal position control unit (502) controls a condenser drive unit (340) so that the focal point of the laser beam is positioned at a predetermined position in the orthogonal direction. A current control unit (501) controls a current scanner unit (32) so as to change the amplitude of the laser beam oscillation according to the position of the focal point in the orthogonal direction.)

1. A laser processing machine is characterized by comprising:

a processing head which emits a laser beam;

a condenser lens for converging the laser beam and irradiating the laser beam onto a metal plate to form a beam spot on a surface of the metal plate;

a moving mechanism that moves the machining head relative to the metal plate along a surface of the metal plate;

a beam vibration mechanism configured to vibrate the laser beam when the laser beam is irradiated to the metal plate while the machining head is relatively moved by the movement mechanism to cut the metal plate;

a focus moving mechanism that moves a focus of the laser beam irradiated to the metal plate in an orthogonal direction orthogonal to a surface of the metal plate;

a focal point position control unit for controlling the focal point moving mechanism so that the focal point is positioned at a predetermined position in the orthogonal direction; and

and a beam vibration mechanism control unit that controls the beam vibration mechanism so as to change an amplitude of the laser beam in accordance with the position of the focal point in the orthogonal direction when the focal point position control unit controls the focal point moving mechanism so as to change the position of the focal point in the orthogonal direction.

2. The laser processing machine according to claim 1,

further comprises a data holding unit for holding beam profile data indicating a beam diameter corresponding to a position in the traveling direction of the laser beam,

the beam oscillation mechanism control unit determines an amplitude of oscillation of the laser beam with reference to the beam profile data.

3. The laser processing machine according to claim 2,

the beam vibration means sets the amplitude of the laser beam vibration to a reference amplitude when the focal point is at the reference position in the orthogonal direction,

based on the beam profile data, when the beam diameter of the beam spot on the surface of the metal plate when the focal point is at the reference position is a first beam diameter and when the beam diameter of the beam spot on the surface of the metal plate when the focal point is at a predetermined position other than the reference position is a second beam diameter, the beam vibration mechanism control unit controls the beam vibration mechanism so that the laser beam vibrates with an amplitude obtained by subtracting a difference from the reference amplitude when the focal point of the laser beam is at the predetermined position other than the reference position, the difference being a value obtained by subtracting the first beam diameter from the second beam diameter.

4. A laser processing method is characterized in that,

irradiating the surface of the metal plate with a laser beam condensed by a condenser lens;

moving a laser beam relative to an irradiation position of a surface of the metal plate to cut the metal plate;

vibrating the laser beam in a predetermined vibration mode when cutting the metal plate;

when the focal point of the laser beam is moved in a direction orthogonal to the surface of the metal plate, the amplitude of the vibration of the laser beam in the vibration mode is changed according to the position of the focal point in the orthogonal direction.

5. The laser processing method according to claim 4,

the amplitude of the vibration of the laser beam is determined by referring to beam profile data stored in a data holding unit and indicating a beam diameter corresponding to a position in a traveling direction of the laser beam.

6. The laser processing method according to claim 5,

setting the amplitude of the vibration mode when the focal point is at the reference position in the orthogonal direction as a reference amplitude,

based on the beam profile data, when the beam diameter of the beam spot on the surface of the metal plate when the focal point is at the reference position is a first beam diameter, and when the beam diameter of the beam spot on the surface of the metal plate when the focal point is at a predetermined position other than the reference position is a second beam diameter, the laser beam is vibrated at an amplitude obtained by subtracting a difference value from the reference amplitude when the focal point is at the predetermined position other than the reference position, the difference value being a value obtained by subtracting the first beam diameter from the second beam diameter.

Technical Field

The present disclosure relates to a laser processing machine and a laser processing method for processing a metal plate with a laser beam.

Background

A laser processing machine has been widely used which cuts a metal plate with a laser beam emitted from a laser oscillator to produce a product having a predetermined shape. Non-patent document 1 describes: the metal plate is cut while vibrating the laser beam in a predetermined vibration mode.

Documents of the prior art

Non-patent document

Non-patent document 1 January 2017The FABRICATOR 67, Shaping The beam for The beam cut

Disclosure of Invention

Problems to be solved by the invention

When a metal plate is cut by a laser processing machine, the focal point of a laser beam is positioned at a predetermined position in a direction perpendicular to the surface of the metal plate. Specifically, the laser beam machine may cut the metal plate by positioning the focal point of the laser beam just above the upper surface of the metal plate. A laser processing machine sometimes cuts a metal plate by positioning a focal point of a laser beam above an upper surface of the metal plate by a predetermined distance. A laser processing machine sometimes cuts a metal sheet by positioning a focal point of a laser beam below an upper surface of the metal sheet by a predetermined distance and within a thickness of the metal sheet.

In this way, the laser processing machine cuts the metal plate by appropriately setting the relative position of the focal point of the laser beam with respect to the metal plate. An object of one or more embodiments is to provide a laser processing machine and a laser processing method that can satisfactorily cut a metal plate even when a focal point of a laser beam is moved in a direction orthogonal to a surface of the metal plate when the metal plate is cut while the laser beam is vibrated in a predetermined vibration mode.

Means for solving the problems

According to a first aspect of one or more embodiments, there is provided a laser processing machine including: a processing head which emits a laser beam; a condenser lens for converging the laser beam and irradiating the laser beam onto a metal plate to form a beam spot on a surface of the metal plate; a moving mechanism that moves the machining head relative to the metal plate along a surface of the metal plate; a beam vibration mechanism configured to vibrate the laser beam when the laser beam is irradiated to the metal plate while the machining head is relatively moved by the movement mechanism to cut the metal plate; a focus moving mechanism that moves a focus of the laser beam irradiated to the metal plate in an orthogonal direction orthogonal to a surface of the metal plate; a focal point position control unit for controlling the focal point moving mechanism so that the focal point is positioned at a predetermined position in the orthogonal direction; and a beam vibration mechanism control unit that controls the beam vibration mechanism so as to change an amplitude of the laser beam in accordance with a position of the focal point in the orthogonal direction when the focal point position control unit controls the focal point moving mechanism so as to change the position of the focal point in the orthogonal direction.

According to a second mode of one or more embodiments, there is provided a laser processing method of irradiating a surface of a metal plate with a laser beam condensed by a condenser lens; moving a laser beam relative to an irradiation position of a surface of the metal plate to cut the metal plate; vibrating the laser beam in a predetermined vibration mode when cutting the metal plate; when the focal point of the laser beam is moved in a direction orthogonal to the surface of the metal plate, the amplitude of the vibration of the laser beam in the vibration mode is changed according to the position of the focal point in the orthogonal direction.

According to the laser processing machine and the laser processing method of one or more embodiments, when cutting the metal plate while vibrating the laser beam in the predetermined vibration mode, the metal plate can be cut satisfactorily even if the focal point of the laser beam is moved in the direction orthogonal to the surface of the metal plate.

Drawings

Fig. 1 is a diagram showing an example of the overall configuration of a laser beam machine according to one or more embodiments.

Fig. 2 is a perspective view showing a detailed configuration example of a collimator unit and a machining head in a laser processing machine according to one or more embodiments.

Fig. 3 is a diagram for explaining displacement of the irradiation position of the laser beam to the metal plate by the beam vibrating mechanism.

Fig. 4 is a diagram showing a parallel vibration mode of a laser beam.

Fig. 5 is a diagram showing the orthogonal vibration mode of the laser beam.

Fig. 6 is a diagram showing an actual vibration mode when the orthogonal vibration mode shown in fig. 5 is used.

Fig. 7 is a partial block diagram showing an example of a detailed configuration of a laser beam machine according to one or more embodiments.

Fig. 8 conceptually shows beam profile data held by the laser processing machine according to one or more embodiments.

Fig. 9 is a graph comparing the prior art and one or more embodiments and showing the amplitude of the laser beam in the vibration mode in a state after moving the focal point of the laser beam from the reference position.

Fig. 10 is a table comparing the prior art and one or more embodiments and showing the cutting results of the metal plate when the focal point of the laser beam is moved from the reference position.

Detailed Description

Hereinafter, a laser processing machine and a laser processing method according to one or more embodiments will be described with reference to the drawings. In fig. 1, a laser processing machine 100 includes: a laser oscillator 10 that generates and emits a laser beam, a laser processing unit 20, and a process fiber 12 that transmits the laser beam emitted from the laser oscillator 10 to the laser processing unit 20.

The laser processing machine 100 includes an operation unit 40, an NC device 50, a processing program database 60, a processing condition database 70, and an auxiliary gas supply device 80. The NC device 50 is an example of a control device that controls each part of the laser processing machine 100.

The laser oscillator 10 is preferably a laser oscillator that amplifies the excitation light emitted from the laser diode and emits a laser beam having a predetermined wavelength, or a laser oscillator that directly uses the laser beam emitted from the laser diode. The laser oscillator 10 is, for example, a solid-state laser oscillator, a fiber laser oscillator, a disk laser oscillator, or a direct diode laser oscillator (DDL oscillator).

The laser oscillator 10 emits a laser beam having a wavelength of 900nm to 1100nm and a wavelength of 1 μm. Taking a fiber laser oscillator and a DDL oscillator as examples, the fiber laser oscillator emits a laser beam having a wavelength of 1060nm to 1080nm, and the DDL oscillator emits a laser beam having a wavelength of 910nm to 950 nm.

The laser processing unit 20 includes: a machining table 21 on which a metal plate W to be machined is placed, a gate-type X-axis carriage 22, a Y-axis carriage 23, a collimator unit 30 fixed to the Y-axis carriage 23, and a machining head 35. The X-axis carriage 22 is configured to be movable in the X-axis direction on the machining table 21. The Y-axis carriage 23 is configured to be freely movable in a Y-axis direction perpendicular to the X-axis on the X-axis carriage 22. The X-axis carriage 22 and the Y-axis carriage 23 function as a moving mechanism that moves the machining head 35 in the X-axis direction, the Y-axis direction, or any synthesis direction of the X-axis and the Y-axis along the surface of the metal plate W.

Instead of moving the machining head 35 along the surface of the metal plate W, the machining head 35 may be fixed in position and the metal plate W may be moved. The laser processing machine 100 may be provided with a moving mechanism for moving the processing head 35 relative to the surface of the metal plate W.

A nozzle 36 is attached to the machining head 35, the nozzle 36 has a circular opening 36a at a distal end portion thereof, and a laser beam is emitted from the opening 36 a. The laser beam emitted from the opening 36a of the nozzle 36 is irradiated to the metal plate W. The assist gas supply device 80 supplies nitrogen, oxygen, a mixed gas of nitrogen and oxygen, or air as an assist gas to the processing head 35. When the metal plate W is processed, the assist gas is ejected from the opening 36a toward the metal plate W. The assist gas discharges the molten metal within the width of the notch after the metal sheet W is melted.

As shown in fig. 2, the collimator unit 30 includes a collimator lens 31 that converts a laser beam of divergent light emitted from the process fiber 12 into parallel light (collimated light). The collimator unit 30 further includes: a current scanner unit 32, and a curved mirror 33 that reflects the laser beam emitted from the current scanner unit 32 downward in a Z-axis direction perpendicular to the X-axis and the Y-axis. The machining head 35 includes a condenser 34 that condenses the laser beam reflected by the curved mirror 33 and irradiates the metal plate W with the condensed laser beam.

Although not shown here, the condenser lens 34 is configured to be freely movable in a direction approaching the metal plate W and in a direction separating from the metal plate W by a condenser lens driving unit 340 (see fig. 7) in order to adjust the focal position of the laser beam.

The laser processing machine 100 is centered so that the laser beam emitted from the opening 36a of the nozzle 36 is positioned at the center of the opening 36 a. In the reference state, the laser beam is emitted from the center of the opening 36 a. The current scanner unit 32 functions as a beam oscillation mechanism that oscillates the laser beam traveling in the processing head 35 and emitted from the opening 36a in the opening 36 a. How the current scanner unit 32 vibrates the laser beam will be described later.

The current scanner unit 32 has: a scanning mirror 321 that reflects the laser beam emitted from the collimator mirror 31, and a drive unit 322 that rotates the scanning mirror 321 at a predetermined angle. In addition, the current scanner unit 32 has: a scan mirror 323 for reflecting the laser beam emitted from the scan mirror 321, and a drive unit 324 for rotating the scan mirror 323 at a predetermined angle.

The driving units 322 and 324 can reciprocally vibrate the scanning mirrors 321 and 323 within a predetermined angular range, respectively, under the control of the NC apparatus 50. The current scanner unit 32 vibrates the laser beam irradiated to the metal plate W by reciprocating either or both of the scanning mirror 321 and the scanning mirror 323.

The current scanner unit 32 is an example of a beam oscillation mechanism, and the beam oscillation mechanism is not limited to the current scanner unit 32 having a pair of scanning mirrors.

Fig. 3 shows a state in which either or both of the scanning mirror 321 and the scanning mirror 323 are tilted and the position of the laser beam irradiated onto the metal plate W is displaced. In fig. 3, a thin solid line bent by the bending mirror 33 and passing through the condenser 34 indicates the optical axis of the laser beam in a state where the laser processing machine 100 is set as a reference.

Further, in detail, by the operation of the galvano scanner unit 32 located in front of the bending mirror 33, the angle of the optical axis of the laser beam incident to the bending mirror 33 is changed, and the optical axis is deviated from the center of the bending mirror 33. In fig. 3, for the sake of simplicity, the incident position of the laser beam to the bending mirror 33 is set to the same position before and after the operation of the current scanner unit 32.

It is assumed that the optical axis of the laser beam is displaced from the position indicated by the thin solid line to the position indicated by the thick solid line due to the action of the current scanner unit 32. If the laser beam reflected by the bending mirror 33 is inclined by the angle θ, the irradiation position of the laser beam onto the metal plate W is shifted by the distance Δ s. If the Focal distance of the condenser 34 is set to EFL (Effective Focal Length), the distance Δ s is calculated by EFL × sin θ.

If the current scanner unit 32 tilts the laser beam by the angle θ in the direction opposite to the direction shown in fig. 3, the irradiation position of the laser beam on the metal plate W can be displaced by the distance Δ s in the direction opposite to the direction shown in fig. 3. The distance Δ s is a distance smaller than the radius of the opening 36a, and preferably, a distance equal to or smaller than a maximum distance that is a distance obtained by subtracting a predetermined margin from the radius of the opening 36 a.

The NC apparatus 50 can vibrate the laser beam in a predetermined direction in the surface of the metal plate W by controlling the driving portions 322 and 324 of the current scanner unit 32. By vibrating the laser beam, the beam spot formed on the surface of the metal plate W can be vibrated.

The laser processing machine 100 configured as described above cuts the metal plate W with the laser beam emitted from the laser oscillator 10 to produce a product having a predetermined shape. The laser processing machine 100 cuts the metal sheet while vibrating the laser beam in a predetermined vibration mode by positioning the focal point of the laser beam at a predetermined distance above the upper surface of the metal sheet W or at a predetermined distance below the upper surface and at any appropriate position within the thickness of the metal sheet W.

An example of a vibration mode in which the NC apparatus 50 vibrates the laser beam by the current scanner unit 32 will be described with reference to fig. 4 and 5. The cutting direction of the metal plate W is defined as the x direction, and the direction perpendicular to the x direction in the surface of the metal plate W is defined as the y direction. The NC apparatus 50 can select any one of the vibration modes in accordance with an instruction from the operator of the operation unit 40. When a vibration pattern is set in the machining conditions stored in the machining condition database 70, the NC apparatus 50 selects the vibration pattern set by the machining conditions.

Fig. 4 and 5 show the vibration pattern in a state where the machining head 35 is not moved in the x direction, so that the vibration pattern can be easily understood. Fig. 4 is a vibration pattern in which the beam spot Bs is vibrated in the x direction in the groove Wk formed by the progress of the beam spot Bs. The vibration mode shown in fig. 4 is assumed to be called a parallel vibration mode. If the frequency of vibrating the beam spot Bs in the direction parallel to the cutting proceeding direction is Fx and the frequency of vibrating in the direction orthogonal to the cutting proceeding direction is Fy, the parallel vibration mode is Fx: fy is 1: vibration mode of 0.

Fig. 5 is a vibration pattern for vibrating the beam spot Bs in the y direction. By vibrating the beam spot Bs in the y direction, the groove Wk becomes a notch width K2 wider than the notch width K1. The vibration mode shown in fig. 5 is assumed to be called a quadrature vibration mode. The orthogonal vibration modes are Fx: fy is 0: 1 vibration mode.

The NC apparatus 50 may also vibrate the laser beam in a vibration mode combining vibration in the x direction and vibration in the y direction. The first example of the other vibration modes is a circular vibration mode in which the laser beam is vibrated in a circular shape so that the beam spot Bs draws a circle. A second example of the other vibration mode is an 8-shaped vibration mode in which the laser beam is vibrated in an 8-shaped pattern in such a manner that the beam spot Bs draws the numeral 8. A third example of the other vibration mode is a C-shaped vibration mode in which the laser beam is vibrated in such a manner that the beam spot Bs draws a letter C.

In practice, since the laser beam is vibrated while moving the machining head 35 in the cutting direction, the vibration mode is a vibration mode in which a displacement in the cutting direction (x direction) is added to the vibration mode shown in fig. 4 or 5 or another vibration mode not shown. Taking the orthogonal vibration mode shown in fig. 5 as an example, the spot Bs vibrates in the y direction while moving in the x direction, and thus the actual orthogonal vibration mode is the vibration mode shown in fig. 6.

Next, a specific configuration will be described in which, when the laser processing machine 100 cuts the metal sheet W while vibrating the laser beam in the predetermined vibration mode, the metal sheet W is cut satisfactorily even if the focal point of the laser beam is moved in a direction perpendicular to the surface of the metal sheet W.

As shown in fig. 7, the NC apparatus 50 includes a current control unit 501, a focal position control unit 502, and a data holding unit 503. The current control unit 501 is supplied with: movement vector information indicating whether or not the machining head 35 is moved in any one of the X direction and the Y direction, and a vibration mode selection signal. Based on the movement vector information, the x direction, which is the cutting travel direction of the metal plate W, and the y direction orthogonal thereto are determined.

The current control section 501 controls one or both of the drive sections 322 and 324 of the current scanner unit 32 so that the laser beam vibrates in the vibration mode selected by the vibration mode selection signal. The current control unit 501 is an example of a beam vibration mechanism control unit that controls the beam vibration mechanism.

The focal position control unit 502 controls the condenser driving unit 340 so that the focal position is set by the processing conditions. The condenser driving unit 340 is an example of a focus moving mechanism that moves the focus of the laser beam irradiated to the metal plate W in a direction perpendicular to the surface of the metal plate W. The focal position of the laser beam may be adjusted by a method other than moving the condenser lens 34.

When the focal position control unit 502 controls the condenser drive unit 340 to move the focal point, the focal position control unit 502 supplies the current control unit 501 with focal point movement information indicating in which direction the focal point is moved upward or downward, how much the focal point is moved. As described later, the current control section 501 controls the drive sections 322 and 324 based on the focus movement information.

The data holding unit 503 holds beam profile data. Fig. 8 conceptually represents beam profile data. The beam profile data indicates beam diameters at respective positions in the traveling direction of the laser beam when the laser beam of the received light is most converged at the beam waist and then diverged. The data holding unit 503 may hold the beam diameter at intervals of, for example, 1mm in the traveling direction of the laser beam as beam profile data.

Assume that FP is 0.0 in a state where the beam waist, which is the focal point of the laser beam, is exactly located at the so-called positive focal point on the upper surface of the metal plate W. The beam diameter in the beam waist is 120 μm. When the focal point is moved to a distance of, for example, 2.0mm above the metal plate W, a beam spot Bs having a beam diameter at a position FP of +2.0 is irradiated onto the upper surface of the metal plate W. The beam diameter is 148 μm, for example. Similarly, when the focal point is moved to a distance of, for example, 2.0mm below the metal plate W, the beam spot Bs having a beam diameter at a position FP of-2.0 is irradiated onto the upper surface of the metal plate W. The beam diameter at this time was also 148 μm.

The distance at which current control unit 501 controls drive units 322 and 324 to vibrate beam spot Bs as shown in fig. 4 or 5 is set on the assumption that the straight beam at the position FP of 0.0 is irradiated to the upper surface of metal plate W at the positive focal point.

As shown in fig. 9, assuming the orthogonal vibration mode shown in fig. 5 as an example, the amplitude of the laser beam in the y direction is set to the reference amplitude Qy0 in a state of an orthogonal focus point where FP is 0.0. In fig. 9, the reference amplitude Qy0 is illustrated more exaggerated than in fig. 5 for ease of understanding. In addition, the beam diameter when FP is 0.0 and the beam diameter when FP is +2.0 are shown more exaggerated than the actual size ratio.

When the focal point position control unit 502 controls the condenser lens driving unit 340 so that FP becomes +2.0, the beam diameter becomes 148 μm. In the related art, the amplitude of the laser beam vibration is the reference amplitude Qy0 regardless of the position in the orthogonal direction of the surface of the metal plate W at which the focal point of the laser beam is located. Therefore, the irradiation range of the laser beam in the y direction of the metal plate W is larger than the irradiation range y0 in the y direction when FP is 0.0.

In one or more embodiments, the current control section 501 controls the drive section 322 or 324 so that the amplitude of the laser beam in the y direction is Qy2, with reference to the beam profile data and based on the focal point movement information supplied from the focal point position control section 502, to maintain the irradiation range y0 in the y direction.

When the beam diameter at FP of 0.0 is generalized to r0 and the beam diameter at FP of +2.0 is generalized to r2, the current controller 501 may determine the amplitude Qy2 by the formula Qy2 of Qy0- (r2-r 0).

That is, assume that: based on the beam profile data, the beam diameter of the beam spot Bs on the surface of the metal plate W when the focal point of the laser beam is at the reference position is a first beam diameter, and the beam diameter of the beam spot Bs on the surface of the metal plate W when the focal point is at a predetermined position other than the reference position is a second beam diameter. Preferably, FP is 0.0 as the reference position. The current control section 501 may control the current scanner unit 32 so that the laser beam vibrates with an amplitude obtained by subtracting a difference, which is obtained by subtracting the first beam diameter from the second beam diameter, from the reference amplitude Qy0 when the focal point of the laser beam is located at a predetermined position other than the reference position.

In fig. 9, the orthogonal vibration mode shown in fig. 5 is taken as an example, but similarly in the case of the parallel vibration mode shown in fig. 4 or other vibration modes, the current control section 501 changes the amplitude in accordance with the relative position of the focal point with respect to the metal plate W.

As described above, according to one or more embodiments, even if the focal point of the laser beam moves, the amplitude of each vibration mode changes, and therefore, the irradiation range of the laser beam when the beam spot Bs is located at both ends in the vibration direction can be made constant. The irradiation range of the laser beam is a distance between both outer sides when the beam spot Bs is located at both ends in the vibration direction. According to one or more embodiments, since the preset irradiation range can be maintained, the metal plate W can be cut satisfactorily even if the focal point of the laser beam is moved.

In particular, when setting the notch width of the groove Wk formed when cutting the metal plate W in the orthogonal vibration mode, it is not preferable to change the notch width by moving the focal point of the laser beam. According to one or more embodiments, the metal plate W can be cut without changing the slit width.

However, according to one or more embodiments, the following effects are also provided: when the focal point is moved in the direction perpendicular to the surface of the metal plate W, the range in which the metal plate W can be cut can be enlarged. Fig. 10 shows the experimental results when mild steel having a thickness of 12mm as the metal plate W was cut using orthogonal vibration modes and different focal positions of FP 0.0 to +7.0 at intervals of 1.0 mm.

As shown in fig. 10, in the related art, the amplitude Qy is made constant at 400 μm regardless of the position in the orthogonal direction of the focal point. In fig. 10, "good" indicates that the metal sheet W can be cut with good quality of cut surface, and "good" indicates that the metal sheet W can be cut without good quality of cut surface, and "not" indicates that the metal sheet W cannot be cut. In the case of the conventional technique in which the amplitude Qy is constant at 400 μm, good, ok, not, ok, and not-ok results were obtained at FP of 0.0 to +7.0, respectively.

In one or more embodiments, the amplitude Qy at FP of 0.0 is 400 μm of the reference amplitude Qy0, and the amplitudes Qy are 398, 388, 366, 343, 319, 293, 269 μm at FP of +1.0 to +7.0, respectively. At FP of 0.0 to +7.0, respectively, good, fair, and ineligible results were obtained. Thus, according to one or more embodiments, the range in which the metal plate W can be cut can be expanded. In addition, according to one or more embodiments, the range in which the metal plate W can be cut off satisfactorily can be expanded.

Fig. 10 shows the results of the experiment using mild steel as the metal plate W, but the irradiation range of the laser beam is not maintained, and therefore, similar effects can be obtained even if the metal plate W is made of stainless steel or aluminum alloy.

The present invention is not limited to the one or more embodiments described above, and various modifications can be made without departing from the scope of the present invention.

The disclosure of the present application is associated with the subject matter recited in application docket No. 2018-193150 filed on 12.10.2018, the entire contents of which are incorporated herein by reference.