JP6378885B2 - Laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to a laser processing apparatus and a laser processing method, and more particularly to a laser processing apparatus and a laser processing method suitable for continuous opening processing of a plurality of holes.

The applicant of the present application discloses a technique for opening a square hole in a workpiece at high speed by laser processing.
The laser processing method described in Patent Document 1 has a loop-shaped path that connects a laser beam processing path from a cutting end point on one side of a square hole to a cutting start point on the next side. Turn it on at the cutting start point and turn it off at the cutting end point. Thereby, it is not necessary to decelerate the machining head, and the square hole can be machined at high speed.

JP-A-10-080784

When performing the drilling process at a higher speed, it is preferable to bring the nozzle tip of the machining head and the workpiece as close as possible, including the cutting start time point at which the laser beam irradiation is turned on.
However, since the cutting start point for opening is a piercing process by irradiating a laser beam to a place where no hole is formed in the workpiece, sputtering is likely to occur.
For this reason, the spatter is likely to adhere to the surface around the cutting start point of the workpiece, and there is a possibility that the appearance quality is deteriorated.
Further, the shorter the distance between the nozzle and the workpiece, the easier the spatter adheres to the nozzle. If spatter adheres to the nozzle, the processing quality may be degraded.

  Therefore, the problem to be solved by the present invention is to provide a laser processing apparatus and a laser processing method capable of performing hole opening processing at high speed and with high quality.

In order to solve the above problems, the present invention has the following configuration and procedure.
1) the workpiece, a machining head to the predetermined injection region definitive near the irradiation position of the irradiation and the laser light of the laser beam performing the injection of the mist,
A moving unit that moves the machining head along the workpiece;
A laser oscillator for supplying the laser beam to the processing head;
A liquid supply device for supplying a liquid to be the mist to the processing head;
A control unit for controlling operations of the moving unit, the laser oscillator, and the liquid supply device;
With
The processing head, when moving, injects the mist to the front side in the moving direction with respect to the irradiation position of the laser beam,
The controller is
While moving the processing head along a predetermined path, when continuously cutting a part of each of a plurality of predetermined shapes on / off of the laser beam,
When the processing of the on-time of the irradiation of the laser light is piercing in the workpiece, definitive the processing head prior to turning on the irradiation of the laser beam moving at said predetermined path, said piercing The mist spraying is turned on when the predetermined spray region reaches a processing position, and the operation of the liquid supply device is controlled so that the liquid film is formed at and near the processing position. It is a laser processing apparatus.
2) The control unit
To form a film of said liquid prior to turning on the irradiation of the laser beam, the timing for turning on the injection of the mist, causes preceded by a predetermined time than the timing of turning on the irradiation of the laser beam The machining head is moving with the laser beam irradiation turned on along the predetermined path, before the laser beam reaches the machining end point and after the mist injection area reaches the machining end point. The laser processing apparatus according to 1), wherein operation of the liquid supply apparatus is controlled to turn off the mist injection .
3) The laser processing apparatus according to 2), wherein the control unit sets the predetermined time according to a moving speed of the processing head.
4) The control unit continuously turns on the mist injection including at least one off period in which the irradiation is off in the processing of repeating the on / off operation of the laser light irradiation a plurality of times. The laser processing apparatus according to any one of 1) to 3), wherein an operation of the liquid supply apparatus is controlled to be as follows.
5) the workpiece, a machining head for ejecting the mist predetermined injection region definitive near the irradiation position of the irradiation and the laser light of the laser beam, and a moving unit that moves along the machining head into the workpiece, A laser oscillator for supplying the laser light to the processing head, a liquid supply device for supplying the mist liquid to the processing head, and a control for controlling operations of the moving unit, the laser oscillator, and the liquid supply device A plurality of square holes are formed in the workpiece using a laser processing apparatus capable of injecting the mist at least on the front side in the moving direction of the processing head with respect to the irradiation position of the laser light. A laser processing method,
The shape of the plurality of square holes is virtually divided into a plurality of portions, and the laser beam irradiation is turned on / off continuously by moving one of the plurality of square holes while moving the machining head. A square hole forming step for sequentially cutting and cutting,
When the processing start point of the part is pierced, before the irradiation position of the laser beam with irradiation turned off reaches the processing start point of the part while moving the processing head along the predetermined path A mist injection step of turning on the mist injection when the predetermined injection region reaches the processing start point ;
The laser processing method characterized by including.

  According to the present invention, it is possible to obtain an effect that the hole forming can be performed at high speed and with high quality.

It is a whole figure for demonstrating the laser processing apparatus 51 which is an Example of the laser processing apparatus which concerns on embodiment of this invention. It is a schematic diagram for demonstrating the processing head 24 of the laser processing apparatus 51. FIG. FIG. 5 is a schematic diagram for explaining a region where a laser beam L, an assist gas AG, a mist FM, and a mist FM2 that reach the workpiece W are emitted from a nozzle 25 of the processing head 24; It is a figure for demonstrating the example of a process by the laser processing apparatus 51. FIG. It is a figure for demonstrating on / off operation | movement of the laser beam L and the mist FM in the process example. It is a figure for demonstrating the difference in the on / off timing of the laser beam L and mist FM.

  A laser processing apparatus and a laser processing method according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6 using a laser processing apparatus 51 of an example and a processing method using the same.

First, the overall configuration of the laser processing apparatus 51 of the embodiment will be described with reference to FIG. FIG. 1 is an overall perspective view of the laser processing apparatus 51.
The laser processing apparatus 51 is a fiber laser processing apparatus, which irradiates a workpiece W, which is a workpiece, with a laser beam, and processes the workpiece W such as opening.
The laser processing device 51 includes a fiber laser oscillator 10 that is a laser light source, a main body unit 20 that irradiates the workpiece W with laser light output from the fiber laser oscillator 10, and processes the workpiece W, a control unit 30a, and a storage unit. A control device 30 that controls the overall operation of the laser processing device 51, an assist gas supply device 41 that supplies assist gas to the processing head 24 included in the main body 20 while controlling the air, and air (air ) And a liquid supply device 43 that supplies liquid (for example, water or oil) to be ejected as mist FM from the nozzle 25 of the processing head 24 while controlling the air supply device 42. Has been.
The operations of the assist gas supply device 41, the air supply device 42, and the liquid supply device 43 are controlled by the control unit 30a.

  Processing information including a processing program is supplied to the control device 30 from an external data server or the like. In addition to the machining program, the machining information includes information necessary for machining such as the material of the workpiece W to be machined and machining dimensions. The supplied machining information is stored in the storage unit 30b and is referred to by the control unit 30a.

  The fiber laser oscillator 10 oscillates a laser beam according to an instruction from the control unit 30a. A process fiber 8 is connected between the fiber laser oscillator 10 and a processing head 24 described later. The laser beam generated by the fiber laser oscillator 10 is supplied to the processing head 24 via the process fiber 8.

The main body 20 has a processing table 21 having a mounting surface 21a on which the workpiece W is mounted, and an X-axis carriage 22 that is provided on the processing table 21 and moves in one direction (X-axis direction) along the mounting surface 21a. And have.
The X-axis carriage 22 is provided with a Y-axis carriage 23 that moves along the placement surface 21a and moves in the Y-axis direction perpendicular to the X-axis direction. The X-axis carriage 22 and the Y-axis carriage 23 are also referred to as moving parts.
A processing head 24 is attached to the Y-axis carriage 23 so as to be movable in the Z-axis direction (direction orthogonal to the X-axis and the Y-axis).
The X-axis carriage 22, the Y-axis carriage 23, and the machining head 24 are moved independently of each other by driving of a driving unit (not shown) under the control of the control unit 30a.

As described above, the processing fiber 8 is connected to the processing head 24 and supplied with the laser light output from the fiber laser oscillator 10.
The processing head 24 includes a housing 24a, an optical system 24b that is a focus adjustment unit provided in the housing 24a, and a nozzle 25 attached to the tip of the housing 24a.
The optical system 24b performs predetermined optical processing on the supplied laser light, and irradiates the processing table 21 with laser light from the nozzle 25 onto the axis CL25.
In the optical processing by the optical system 24b, the processing head 24 can set at least a focal position (focus position) of a laser beam to be irradiated (hereinafter referred to as laser beam L) to a predetermined position in the thickness direction of the workpiece W. It is like that. That is, the focal position can be adjusted in the Z-axis direction.
This adjustment operation is controlled by the control unit 30a.

Further, an assist gas blown out from the nozzle 25 for removing a gas or a melt generated along with the laser processing is supplied from the assist gas supply device 41.
Further, in the machining head 24, a liquid that becomes a mist FM to be sprayed from the nozzle 25 to the workpiece W and air (air) for mist-forming the liquid in the opening machining are respectively supplied to the liquid supply device 43 and the air supply device. 42.

  The machining head 24 can move at least two-dimensionally along the workpiece W in a range facing the workpiece W by the cooperative operation of the X-axis carriage 22 and the Y-axis carriage 23. Further, it is possible to perform processing by irradiating a desired processing point Wp of the workpiece W with the laser beam L at a predetermined focal position.

FIG. 2 is a schematic diagram for explaining the machining head 24 in detail.
The machining head 24 is provided with a mist nozzle 1 for injecting mist FM around the irradiation position of the laser light L on the workpiece W.
Further, the machining head 24 is provided with a mist nozzle 2 for injecting a mist FM as a refrigerant in the vicinity of the outer side in the radial direction of the laser beam L to be irradiated, like the mist nozzle 1.
Liquid is supplied to the mist nozzle 1 and the mist nozzle 2 from the liquid supply device 43 through the on-off valves V1 and V2, respectively.
The on-off valve V1 and the on-off valve V2 are controlled to open / close and flow by the control unit 30a.
Therefore, the injection of the mist FM and the mist FM2 from the mist nozzle 1 and the mist nozzle 2 can be selectively executed from the options of having both, not having both, and having only one of them. In addition, it is possible to adjust the injection amount when it is assumed that there is injection.

The mist nozzle 2 injects the mist to a position outside the injection range of the mist FM by the mist nozzle 1, and is integrally attached to a ring gear 3 that is rotatable on a horizontal plane.
The ring gear 3 meshes with a pinion 4 a provided on the output shaft of the motor 4, and is rotated by driving the motor 4. The driving of the motor 4 is controlled by the control unit 30a.
Therefore, the circumferential position of the mist nozzle 2 integrated with the ring gear 3 with respect to the laser light L can be controlled by controlling the driving of the motor 4.
Thereby, the circumferential direction position of the mist nozzle 2 with respect to the laser beam L can be located, for example, in the traveling direction front side of the laser cutting processing position by the processing head 24.

  As described above, when the workpiece W is irradiated with the laser light L to be cut, mist can be injected to a predetermined position.

  The assist gas AG (see FIG. 3) is injected from the nozzle 25 toward the workpiece W together with the laser light L.

FIG. 3 conceptually shows an arrival area when the laser beam L emitted from the mist nozzle 1, the assist gas AG to be ejected, and the mist FM to be ejected reach the work W.
That is, a circular range including the light beam of the laser beam L (hatching is provided) is an arrival region of the assist gas AG, and an arrival region of the ring-like mist FM by the mist nozzle 1 exists outside the arrival region of the assist gas AG. To do. In addition, the arrival area of the mist FM2 in a spot shape by the mist nozzle 2 exists outside the arrival area of the mist FM.

  Next, a description will be given of a processing example in which a hole is formed in the workpiece by the laser processing apparatus 51 including the processing head 24 described above.

  In detail, with reference to FIGS. 4-6, the process example which forms the some square hole W1a in the grid | lattice form in the workpiece | work W1 is demonstrated. This example involves mist injection during laser processing. First, for easy understanding, the movement path of the machining head 24 and the on / off operation of the laser light L will be described with reference to FIGS. 4A and 4B, and then the mist injection operation will be described.

FIG. 4A is a plan view showing a state after the workpiece W1 is processed, that is, a state in which a plurality of square holes W1a are arranged in a lattice shape. In this example, the workpiece W1 is assumed to have nine square holes W1a of 3 rows and 3 columns. Each square hole W1a has the same shape, and is formed with a length D1 of the vertical side (column side) and a length D2 of the horizontal side (row side).
FIG. 4B shows a locus of the position of the laser light L (axis line CL25) with respect to the workpiece W1 in the drilling process of the plurality of square holes W1a. The control unit 30a controls the operations of the X-axis carriage 22 and the Y-axis carriage 23 so that the laser light L moves along this locus.
The solid line is a state in which the irradiation of the laser beam L is turned on by the control unit 30a and the laser beam L is applied to the workpiece W1, and the broken line is turned off and the laser beam L is irradiated to the workpiece W1. It is not in a state.
For the sake of explanation, the sides corresponding to the rows in each square hole are defined in alphabetical order, and the sides corresponding to the columns are defined in alphabetical order.

  First, the processing head 24 turns off the laser from the outside of the workpiece W1 and moves to the processing start point a1a of the side a1 and cuts the sides i1, i2, and i3 corresponding to the row A in this order. To do. When the processing head 24 moves to a position corresponding to each side, the laser beam L is turned on (solid line), and when the machining head 24 moves to a non-corresponding position, it is turned off (broken line).

When the processing head 24 reaches the processing end point A3b of the side A3, the laser light L is turned off and moves along the semi-arc path K1a, and the sides B3, B2. B 1 is processed in this order by executing the same on / off operation as in row B.
When the processing head 24 reaches the processing end point B1b of the side B1, the laser beam L is turned off to move along the semi-arc path K1b, and the side C1, C2, C3 corresponding to the C row are Processing is performed by executing the same on / off operation as in the row A and row B in this order. Hereinafter, similarly, the sides of the second row to the second row are processed.
In the row processing, piercing processing is performed in which the processing start point of each side is opened in a place where there is no hole in the workpiece W1.

When the processing head 24 passes the processing end point 1b of the side 1 to be processed at the end of the side corresponding to the column, the processing head 24 moves along the loop-shaped path K1R and corresponds to the A line of the same square hole as the side 1 The side A3 is processed first, and then the sides A2 and A1 are processed in this order. The path K1R may be set so that the machining head 24 moves along a path where the speed change is as small as possible. The path K1R may be set so as to move not only in a semi-arc path but also in other movement paths.
The machining head 24 is turned on (solid line) when moving the position corresponding to each side, and is turned off (broken line) when moving the non-corresponding position.
After passing the machining end point A1b of the side A1, the laser beam L is turned off to move the semi-arc-shaped a3, and the sides B1, B2, B3 corresponding to the B row are turned on / off in this order as in the A row. Execute the operation and process it. The processing end point A1b is the same point (position) as the processing start point A1a of the side A1.
Hereinafter, similarly, the sides of the C line to the F line are processed.
When the position of the axis CL25 passes the processing end point F3b of the side F3 to be processed at the end of the side corresponding to the row, the processing head 24 turns off the laser light L and retreats out of the workpiece W1. As a result, the processing ends (END).

FIG. 5 is a diagram for explaining a command (hereinafter also referred to as a beam command) for on / off operation of the laser light L by the control unit 30a.
FIG. 5 shows an on / off operation command in the machining example. The beam command Sg1 is a command sent from the control unit 30a to the fiber laser oscillator 10.

The beam command Sg1 is turned ON when the laser beam L is on the path indicated by the solid line arrow shown in FIG. 4B during the movement of the machining head 24, and the position of the axis CL25 is set on the path indicated by the broken line. It is turned off (OFF).
Here, the ON period d1 in the beam command Sg1 is a period corresponding to one side (for example, a2) in the row processing. The on period d2 is a period corresponding to one side (for example, A2) in the row processing.
Therefore, d1 / d2 = D1 / D2.

The off period varies depending on the path length of the broken line shown in FIG. 4B and the like (in FIG. 5, it is shown equally for convenience).
For example, in the beam command Sg1 in FIG. 5, the off period between the on period corresponding to A3 and the on period corresponding to B3 corresponds to the path K1a. An off period between the on period corresponding to F1 and the on period corresponding to A3 corresponds to the path K1R.

A mist command Sg2 shown in FIG. 5 is a command sent from the control unit 30a to the liquid supply device 43.
The mist command Sg2 is turned on in response to each turn-on of the beam command Sg1 in the column processing, and is turned off in the row processing after the column processing is completed.

By this mist command Sg2, the mist FM is jetted before the laser beam L is applied to the part to be pierced by the laser beam L.
By this jetting, a film of liquid (in this example, water) is formed on the surface of the workpiece W1, and the liquid film is irradiated with the laser light L. Thereby, the amount of spatter adhering to the surface of the workpiece W1 is reduced while piercing.
Further, since the sputtering hardly adheres to the nozzle 25, the nozzle 25 can be brought closer to the workpiece W1.
In the row processing performed after the column processing is completed, in the processing example, the processing start point of each side of the row is matched with the processing end point of the side formed in advance by the column processing. As a result, the row processing is not pierced, and the occurrence of spatter is extremely small.
Therefore, the mist FM does not necessarily have to be injected in the row processing.
FIG. 5 shows a mist command Sg2 for stopping the injection of the mist FM in the row machining.

The start time of each ON period in the mist command Sg2 is not simultaneously with the start time of each ON period of the corresponding beam command Sg1, but starts in advance by time Δt1.
In addition, the end time of each on period in the mist command Sg2 is not simultaneous with the end time of each on period of the corresponding beam command Sg1, but ends in advance by time Δt2.
This will be described with reference to FIGS. 6 (a) and 6 (b).

Here, mist is demonstrated as what is ejected | emitted only from the mist nozzle 1. FIG. FIG. 6A is a diagram showing the side LN1 to be processed with the laser light L turned on, the position of the laser light L toward the side LN1, and the ejection range of the mist FM (corresponding to FIG. 3).
The unprocessed portion on the side LN1 is indicated by a white dot-and-dash line, and the processed portion is indicated by a solid black. In addition, an area AR1 sandwiched between parallel two-dot chain lines and an area AR2 surrounded by the injection range are areas where the mist FM has been injected. The same applies to FIG. 6B.

As shown in FIG. 6A, the tip position FM1 in the traveling direction of the ring-shaped injection region reaches before the laser beam L reaches the processing start position of the side LN1.
Since the injection region is ring-shaped, by turning on the mist injection at this time, a liquid film is formed in the vicinity of the processing start position at the start of processing of the side LN1 by the laser light L.
Thus, the time from when the mist injection is turned on until the laser beam L reaches the processing start position of the side LN1 is the time Δt1.

FIG. 6B is a diagram illustrating a state in which the laser beam L is turned on and the side LN1 is being processed, and the tip position FM1 of the injection region has reached the processing end position of the side LN1.
As shown in FIG. 6B, the tip position FM1 in the traveling direction of the ring-shaped injection region reaches before the laser beam L reaches the processing end position of the side LN1.
Therefore, even if the mist injection is turned off at this time, a mist film is already formed up to the processing end position of the side LN1.
Thus, the time from when the mist injection is turned off until the laser beam reaches the processing end position of the side LN1 is the time Δt2.
The control unit 30a sets the time Δt1 and the time Δt2 as predetermined times according to the moving speed of the machining head 24. As the moving speed of the machining head 24 increases, the time Δt1 and the time Δt2 are shortened. When the moving speed of the machining head 24 is constant, Δt1 = Δt2.

By controlling the mist injection in a pulsed manner corresponding to the beam command, the amount of liquid to be used can be minimized. For example, it is desirable to make the time Δt1 equal to the time during which the mist injection is on. That is, by turning off the mist injection after the lapse of time Δt1, the spatter adhesion effect can be obtained with the minimum necessary amount of mist, which is efficient.
In the laser processing apparatus 51, switching between on and off in the beam command Sg1 is executed at a relatively high speed. On the other hand, since the mist injection is liquid discharge control, it is difficult to perform high-speed control of switching, and it is difficult to synchronize with ON / OFF switching of the beam command Sg1.
Therefore, as shown in the mist command Sg3 of FIG. 5, in the row processing, the mist command Sg2 may be continuously turned on from the first on timing to the last off timing without providing an off period.
Further, the timing of turning on when continuously turning on does not have to be the first turning-on timing of the mist command Sg2. Further, the timing of turning off when continuously turning on does not have to be the last timing of turning off the mist command Sg2.
In other words, it may be a mist command that turns on including at least one off period in which the mist command Sg2 is turned off in a plurality of on / off operations.
Further, after the mist is jetted in advance to all positions where piercing is performed, the processing may be performed by turning on / off the laser light L.

As described above, according to the laser processing apparatus and the laser processing method of the embodiment, a liquid film can be formed by ejecting liquid as mist in advance on the surface of a workpiece before irradiation with laser light. Therefore, the spatter adhering to the surface of the workpiece is suppressed, and the appearance quality of the workpiece is improved. Moreover, the adhesion of spatter to the nozzle of the processing head is suppressed.
Further, by using mist injection together, the adhesion of spatter to the workpiece surface and the nozzle is suppressed, so that the shortest machining path including piercing can be set. Thereby, the continuous opening process of a some hole can be performed stably at high speed.

The control unit 30a may include a path setting unit, and based on the machining program, the setting of the continuous drilling machining path and its shortest setting, and the setting of the ON timing of the mist command may be performed.
Alternatively, these settings may be performed on the operator side, the route program may be stored in the storage unit 30b, and the control unit 30a may perform continuous hole drilling with reference to the route program.

  According to the laser processing method of the embodiment, even when piercing has to be performed on a part to be a product of a workpiece, generation of spatter sp can be suppressed by injecting mist. Thereby, high quality processing can be performed regardless of the aperture shape.

  According to the laser processing method described above, when the hole to be formed is a square hole, the control unit 30a virtually divides the shape of the square hole into a plurality of parts (for example, sides) and moves the machining head 24 in the machining procedure. In this case, the step of forming a square hole for sequentially cutting and turning on / off the irradiation of the laser beam L for each part and the processing start point of any of the plurality of parts is pierced, The laser processing apparatus 51 is controlled to include a mist injection step of turning on mist injection before reaching the processing start point.

  The embodiment of the present invention is not limited to the above-described configuration and procedure, and may be modified as long as it does not depart from the gist of the present invention.

The shape of the hole to be drilled is not limited to the square hole described above. For example, a round hole or a hexagonal hole may be used. Moreover, it is not limited to what has two or more holes of the same shape in one workpiece | work, The hole of a different shape may be mixed.
The arrangement of the plurality of holes is not limited to the lattice shape and the staggered shape described above. It may be an irregular array.
The control unit 30a may be disposed outside the laser processing apparatus 51.
The type of laser is not limited to a fiber laser. Another solid-state laser such as a YAG laser may be used, and a gas laser such as a carbon dioxide (CO ₂ ) laser may be used.

DESCRIPTION OF SYMBOLS 1, 2 Mist nozzle 3 Ring gear 4 Motor, 4a Pinion 8 Process fiber 10 Fiber laser oscillator 20 Main-body part 21 Processing table, 21a Mounting surface 22 X-axis carriage, 23 Y-axis carriage 24 Processing head, 24a Case, 24b Optical system 25 nozzle 30 control device, 30a control unit, 30b storage unit 41 assist gas supply device 42 air supply device 43 liquid supply device 51 laser processing device AG assist gas, AR1, AR2 region CL25, CL26 axis D1, D2 length, d1, d2 period FM, FM2 mist, FM1 tip position K1a, K1b, K1R path KD drive unit L laser light, LN1 side SF1 virtual plane Sg1 beam command, Sg2, Sg3 mist command sp Sputter V1, V2 open / close valve W1 work, W1a square hole Δt1, Δt Time

Claims (5)

The workpiece, a machining head for ejecting the mist predetermined injection region definitive near the irradiation position of the irradiation and the laser light of the laser beam,
A moving unit that moves the machining head along the workpiece;
A laser oscillator for supplying the laser beam to the processing head;
A liquid supply device for supplying a liquid to be the mist to the processing head;
A control unit for controlling operations of the moving unit, the laser oscillator, and the liquid supply device;
With
The processing head, when moving, injects the mist to the front side in the moving direction with respect to the irradiation position of the laser beam,
The controller is
While moving the processing head along a predetermined path, when continuously cutting a part of each of a plurality of predetermined shapes on / off of the laser beam,
When the processing of the on-time of the irradiation of the laser light is piercing in the workpiece, definitive the processing head prior to turning on the irradiation of the laser beam moving at said predetermined path, said piercing The mist spraying is turned on when the predetermined spray region reaches a processing position, and the operation of the liquid supply device is controlled so that the liquid film is formed at and near the processing position. Laser processing equipment. The controller is
To form a film of said liquid prior to turning on the irradiation of the laser beam, the timing for turning on the injection of the mist, causes preceded by a predetermined time than the timing of turning on the irradiation of the laser beam The machining head is moving with the laser beam irradiation turned on along the predetermined path, before the laser beam reaches the machining end point and after the mist injection area reaches the machining end point. The laser processing apparatus according to claim 1, wherein an operation of the liquid supply apparatus is controlled to turn off the mist injection .   The laser processing apparatus according to claim 2, wherein the control unit sets the predetermined time according to a moving speed of the processing head.   The control unit continuously turns on the mist injection including at least one off period in which the irradiation is off in the processing of repeating the on / off operation of the laser light irradiation a plurality of times. The laser processing apparatus according to claim 1, wherein an operation of the liquid supply apparatus is controlled. The workpiece, the processing head in a predetermined injection region definitive near the irradiation position of the irradiation and the laser light of the laser beam performing the injection of the mist, a moving unit that moves along the machining head in the workpiece, the processing A laser oscillator for supplying the laser beam to the head, a liquid supply device for supplying the liquid to be the mist to the processing head, a control unit for controlling operations of the moving unit, the laser oscillator, and the liquid supply device; And a laser processing apparatus capable of injecting the mist to at least a front side in the moving direction of the processing head with respect to an irradiation position of the laser light, and forming a plurality of square holes in the workpiece A method,
The shape of the plurality of square holes is virtually divided into a plurality of portions, and the laser beam irradiation is turned on / off continuously by moving one of the plurality of square holes while moving the machining head. A square hole forming step for sequentially cutting and cutting,
When the processing start point of the part is pierced, before the irradiation position of the laser beam with irradiation turned off reaches the processing start point of the part while moving the processing head along the predetermined path A mist injection step of turning on the mist injection when the predetermined injection region reaches the processing start point ;
A laser processing method comprising:

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