JP2021115583A - Laser processing method and laser processing device - Google Patents

Abstract

To provide a laser processing method and a laser processing device which can suppress poor processing.SOLUTION: A laser processing method comprises a processing step SP2 of moving a light condensing spot SP of laser light L on a work-piece 2 to continuously form a plurality of closed regions TrC surrounded by a locus of the light condensing spot SP on the work-piece 2. In the processing step SP2, the light condensing spot SP is scanned so that the light condensing spot SP passes on the already formed closed regions TrC, and then the light condensing spot SP is scanned so as to pass on a region other than the already formed closed regions TrC so that a new closed region TrC is formed, where in forming the new closed region TrC, an average of irradiation energies at the light condensing spot SP at which the work-piece 2 is irradiated in a period of time during which the light condensing spot SP passes on the already formed closed regions TrC is larger than an average of irradiation energies at the light condensing spot SP at which the work-piece 2 is irradiated in a period of time during which the light condensing spot SP passes on the region other than the already formed closed regions TrC.SELECTED DRAWING: Figure 3

Description

The present invention relates to a laser processing method and a laser processing apparatus.

Laser light has advantages such as excellent light-collecting property, high power density, and a small light-collecting spot. Therefore, in recent years, as a means for processing a metal material, a laser processing method of irradiating a laser beam to weld, cut, or modify the metal material may be used.

As such a laser processing method, for example, the method described in Patent Document 1 below is known. In the method described in Patent Document 1, the focused spots are scanned so that the focused spots of the laser light draw a continuous arc locus on one main surface of the work, and a plurality of closed regions are formed. It is formed. In this laser processing method, after a closed region surrounded by the locus of the focused spot is formed on the metal material, the focused spot passes through the closed region when a new closed region is formed. Therefore, the closed regions adjacent to each other partially overlap each other. Patent Document 1 describes that such scanning can increase the processed area and firmly bond the stacked metals to each other.

JP-A-2017-152703

In the laser processing method described in Patent Document 1, it may be preferable to raise the temperature of the work in order to properly process the work. However, if the power of the laser beam is made too strong in order to raise the temperature of the work, the thermal shock applied to the work becomes excessive, and there is a possibility that processing defects such as cracks may occur in the work. On the other hand, if the power of the laser beam is suppressed in order to suppress such processing defects, it is difficult to raise the temperature of the work, and there is a possibility that processing defects of the work may occur due to insufficient temperature.

Therefore, an object of the present invention is to provide a laser processing method and a laser processing apparatus capable of suppressing processing defects.

In order to achieve the above object, the present invention comprises a processing step of moving a focused spot of laser light to continuously form a plurality of closed regions surrounded by loci of the focused spot on the work. In the processing step, the light condensing spot is scanned so as to pass through the already formed closed region, and then the light condensing spot is scanned so as to pass through a region other than the already formed closed region. When the closed region is formed and a new closed region is formed, the average irradiation energy of the focused spot that irradiates the work during the period in which the focused spot passes through the already formed closed region is It is characterized in that it is larger than the average of the irradiation energies of the condensing spot that irradiates the work during the period in which the condensing spot passes through a region other than the already formed closed region.

Further, in order to achieve the above object, the laser processing apparatus of the present invention includes a light source, an emission unit that emits laser light from the light source toward a work, and a moving unit that relatively moves the emission unit and the work. Then, the light-collecting spot of the laser light moving on the work is scanned in a state where the light emitting portion and the work are relatively moving, and a closed region surrounded by the locus of the light-collecting spot is continuously formed on the work. A plurality of scanning units and a control unit are provided, and the control unit controls the moving unit and the scanning unit so that the condensing spot passes through the already formed closed region. When the focused spot is scanned and then the focused spot is scanned so as to pass through a region other than the already formed closed region to form a new closed region and a new closed region is formed. By controlling at least one of the light source and the scanning unit, the average irradiation energy of the focused spot that irradiates the work during the period in which the focused spot passes through the already formed closed region is calculated. It is characterized in that it is made larger than the average of the irradiation energies of the condensing spot that irradiates the work during the period in which the condensing spot passes through a region other than the already formed closed region.

In the laser processing method and the laser processing apparatus as described above, the focused spots of the laser light are moved to continuously form a plurality of closed regions surrounded by the loci of the focused spots on the work. Further, when forming a new closed region, the focused spot is scanned so as to pass through the already formed closed region. Therefore, the period for forming a new closed region in this laser processing method and the laser processing apparatus includes a period during which the condensing spot passes through the already formed closed region and a period during which the condensing spot passes through a closed region other than the already formed closed region. It consists of a passing period. According to this laser processing method and laser processing apparatus, when forming a new closed region, the average irradiation energy during the period in which the condensing spot passes through the already formed closed region is other than the already formed closed region. It becomes larger than the average of the irradiation energy during the period when the focused spot passes through. Therefore, the temperature of the closed region is higher than that in the case where the average of the irradiation energy in the period of passing through the already formed closed region and the average of the irradiation energy in the period of passing through the non-closed region are the same. can do. Therefore, it is possible to suppress processing defects due to insufficient temperature during processing. Further, in such a laser processing method and a laser processing apparatus, the work is preheated by forming a closed region. By preheating the work in this way, it is possible to suppress a sudden rise in the temperature of the work and alleviate the thermal shock to the work. Therefore, processing defects such as cracks due to thermal shock can be suppressed. Further, the case of the laser processing method and the laser processing apparatus of the present invention and the case where the average of the irradiation energy in the period of passing through the closed region and the average of the irradiation energy in the period of forming the closed region are the same. By comparison, when the workpiece is heated to the same temperature and processed, in the former case, the average irradiation energy of the focused spot that irradiates the workpiece during the period in which the focused spot passes through a closed region other than the already formed region is calculated. It can be made smaller, and the impact on the work during this period can be mitigated. As described above, according to the laser processing method and the laser processing apparatus of the present invention, processing defects can be suppressed.

Further, in the laser processing method, when forming a new closed region, the speed of the focused spot moving on the work during the period in which the focused spot passes through the already formed closed region is determined. The average may be slower than the average of the speeds of the focused spots moving on the work during the period in which the focused spots pass other than the already formed closed region.

Further, in the laser processing apparatus, when the control unit forms a new closed region, the control unit controls the scanning unit during a period in which the condensing spot passes through the already formed closed region. The average speed of the condensing spot moving on the work is calculated from the average speed of the condensing spot moving on the work during the period in which the condensing spot passes through a closed region other than the already formed closed region. May be slowed down.

If the speed at which the condensing spot moves on the work is slowed down as described above, the average speed of the condensing spot moving on the work during the period in which the condensing spot passes through the already formed closed region and The time it takes for the focused spot to pass through the closed region is longer than when the average speed of the focused spots moving on the work during the period when the focused spot passes through a closed region other than the already formed closed region is the same. Can be long. Here, the irradiation energy at which the focused spot irradiates the work is proportional to the product of the power of the laser beam forming the focused spot and the time required for the focused spot to advance a unit length on the work. Therefore, if the speed at which the condensing spot moves on the work is set as described above, the irradiation energy during the period of passing through the closed region is increased as compared with the case where the speed of the condensing spot is constant. .. Therefore, the rapid rise in the temperature of the closed region can be suppressed to alleviate the thermal shock to the closed region, and the temperature of the closed region can be raised to a high temperature.

Further, in the laser processing method, when forming a new closed region, the power of the laser light during the period in which the focused spot passes through the already formed closed region is the already formed closed region. Other than that, it may be larger than the power of the laser beam during the period in which the focused spot passes.

Alternatively, in the laser processing apparatus, when the control unit forms a new closed region, the control unit controls the light source to control the light source so that the focused spot passes through the already formed closed region. The power of the laser light may be larger than the power of the laser light during the period in which the focused spot passes through a region other than the closed region where the laser light has already been formed.

If the power of the laser beam is increased as described above, the power of the focused spot during the period of passing through the closed region is the same as the power of the focused spot during the period of forming the closed region. The irradiation energy to be irradiated is increased. Therefore, the rapid rise in the temperature of the closed region can be suppressed to alleviate the thermal shock to the closed region, and the temperature of the closed region can be raised to a high temperature.

Further, the work may be welded by the processing step.

In this case, the work can be welded at a high temperature while mitigating the thermal shock.

Further, the work may be cut by the processing step.

In this case, the work can be cut at a high temperature while mitigating the thermal shock.

Further, the work may be modified by the processing step.

In this case, the work can be modified at a high temperature while mitigating the thermal shock. The reforming means reforming the state of the material forming the work by heat, and examples of such reforming include annealing treatment.

As described above, according to the present invention, there is provided a laser processing method and a laser processing apparatus capable of suppressing processing defects.

It is a perspective view which shows typically an example of the laser processing apparatus which concerns on embodiment of this invention. It is a schematic diagram which mainly shows an example of the internal structure of the laser irradiation apparatus included in the laser processing apparatus shown in FIG. It is a figure which shows an example of the locus drawn by the condensing spot of the laser light emitted from the laser irradiation apparatus shown in FIG. It is a block diagram which includes the control part of the laser processing apparatus shown in FIG. It is a figure for demonstrating the rotation position of a condensing spot in a processing process. It is a figure which shows the relationship between the angular velocity of a condensing spot in a processing process, and the position of a condensing spot on a work. It is a flowchart which shows the process of the laser processing method of this invention. It is a figure which shows another example of the locus drawn by the condensing spot of the laser light emitted from the laser irradiation apparatus shown in FIG.

Hereinafter, a mode for carrying out the laser processing method and the laser processing apparatus according to the present invention will be exemplified together with the attached drawings. The embodiments illustrated below are for facilitating the understanding of the present invention, and are not for limiting the interpretation of the present invention. The present invention can be modified or improved from the following embodiments without departing from the spirit of the present invention. Further, in the present specification, the dimensions of each member may be exaggerated for ease of understanding.

FIG. 1 is a perspective view schematically showing an example of the laser processing apparatus 1 according to the embodiment. As shown in FIG. 1, the laser processing apparatus 1 includes a stage 10, a pair of first guide members 11, a second guide member 12, a laser irradiation apparatus 20, and a control unit 30 as main configurations. ..

The stage 10 is a plate-shaped member, and the work 2 is placed on the main surface 10A on one side of the stage 10. The work 2 of the present embodiment is a stack of two metal plates 2A and 2B. In this embodiment, the metal plates 2A and 2B are welded by the laser processing device 1. The metal plate 2A located above may be, for example, a rolled steel plate SPCC having a thickness of 1 mm, and the metal plate 2B located below may be, for example, an aluminum plate A1050 having a thickness of 1 mm. The lateral direction of FIG. 1 may be referred to as the X direction, and the direction which is the depth direction of FIG. 1 and is perpendicular to the X direction may be referred to as the Y direction.

A pair of first guide members 11 are erected on the respective edges of the main surface 10A of the stage 10 facing each other along the X direction, and each extends in the Y direction. Further, the second guide member 12 extends along the X direction, and both ends of the second guide member 12 in the X direction are placed on the top surface 11T of the first guide member 11.

For example, a rack gear (not shown) is provided on the top surface 11T of the pair of first guide members 11. Further, pinion gears (not shown) that mesh with the rack gear are provided at both ends of the second guide member 12 in the X direction, for example. The second guide member 12 includes a motor (not shown) for rotating these pinion gears. When the motor of the second guide member 12 is driven, the second guide member 12 moves along the Y direction by the rack and pinion mechanism.

The laser irradiation device 20 is attached to the second guide member 12. The laser irradiation device 20 includes, for example, a pinion gear (not shown) and a motor (not shown) for rotating the pinion gear. On the other hand, the second guide member 12 includes, for example, a rack gear (not shown) that meshes with the pinion gear of the laser irradiation device 20. When the motor of the laser irradiation device 20 is driven, the laser irradiation device 20 moves along the X direction by the rack and pinion mechanism.

That is, the laser processing device 1 includes a moving unit that moves the laser irradiation device 20 in the X direction and the Y direction with respect to the work 2. In the laser processing apparatus 1 shown as an example in FIG. 1, the moving portion includes the rack gear provided on the first guide member 11, the pinion gear, the rack gear, and the motor provided on the second guide member 12, and laser irradiation. The pinion gear and the motor provided in the device 20 are included. The moving portion may have another configuration.

FIG. 2 is a schematic view mainly showing an example of the internal structure of the laser irradiation device 20. As shown in FIG. 2, the laser irradiation device 20 includes a housing 21, a light source 22, a plurality of mirrors 23a and 23b, and an emission unit 25 as main configurations.

The housing 21 is a member that internally accommodates the light source 22, a plurality of mirrors 23a, 23b, and the like, and is attached to the second guide member 12 via the rack and pinion mechanism and the like.

The light source 22 is, for example, a fiber laser device, and can emit, for example, a single-mode laser beam L having an output of 1 kW toward the mirror 23a. The laser beam emitted by the light source 22 may be in multi-mode. Alternatively, the light source 22 may be a solid-state laser device, and when the light source 22 is a solid-state laser, it may be, for example, a disk laser device.

The laser beam L is reflected by the plurality of mirrors 23a and 23b and propagates toward the exit portion 25. These plurality of mirrors 23a and 23b are movably attached to the housing 21. Specifically, the mirrors 23a and 23b are attached to an eccentric mechanism 24 configured so that the reflecting surface can be swung and the speed at which the reflecting surface swings can be changed. The eccentric mechanism 24 includes a motor (not shown) attached to the mirrors 23a and 23b, and is attached to the housing 21. The number of the motors of the eccentric mechanism 24 may be one or a plurality. When the eccentric mechanism 24 is driven and the mirrors 23a and 23b are swung, the optical axis LA of the laser beam L emitted from the mirrors 23a and 23b is rotated around a predetermined axis. Further, the angular velocity of the optical axis LA changes as the eccentric mechanism 24 drives and the speed at which the mirrors 23a and 23b oscillate changes. The mirrors 23a and 23b may be composed of one mirror, and the eccentric mechanism 24 may swing the mirror in two directions.

The emitting portion 25 is provided at the lower end portion of the housing 21, and includes a condensing lens. In the present embodiment, the condensing lens condenses the laser light L so that the size of the condensing spot SP on which the laser light L irradiates the work 2 is substantially constant. In the present embodiment, the optical axis LA of the laser beam L rotates about the optical axis 25A of the condensing lens.

In such a laser irradiation device 20, when the light source 22 and the eccentric mechanism 24 are operated without driving the moving portion, the optical axis LA of the laser beam L emitted from the emitting portion 25 causes the optical axis 25A of the condenser lens to operate. Rotate as the center. That is, the condensing spot SP rotates on the work 2 at a predetermined angular velocity, and the locus Tr of the condensing spot SP is drawn on the work 2 in a substantially circular shape. As a result, a closed region TrC surrounded by the locus of the condensing spot SP is formed on the work 2. In the present embodiment, since the size of the condensing spot SP on the work 2 is kept substantially constant by the condensing lens as described above, the line width of the locus of the condensing spot SP is also substantially constant.

The moving unit moves the emitting unit 25 by moving the laser irradiation device 20.

By the way, as described above, according to the laser processing device 1, the laser irradiation device 20, that is, the emitting unit 25 can be moved along the X direction with respect to the work 2. Therefore, by rotating the optical axis LA of the laser beam L and moving the exit portion 25 in the X direction, the locus Tr drawn by the condensing spot SP is stretched in the X direction, and a plurality of closures are made on the work 2. The region TrC is continuously formed along the X direction.

FIG. 3 is a plan view showing an example of the locus of the condensing spot SP in which a plurality of closed region TrCs are continuously formed. In FIG. 3, for ease of understanding, one of the closed region TrCs is shown as an alternate long and short dash line. As described above, in the present embodiment, the optical axis LA of the laser beam L rotates about the optical axis 25A of the condenser lens. That is, in the plan view of FIG. 3, the focused spot SP of the laser beam L rotates about the optical axis 25A. Therefore, by moving the laser irradiation device 20 in the X direction, the optical axis 25A is moved in the X direction at a predetermined sweep speed v, and the condensing spot SP has a predetermined rotational diameter d (see FIG. 2) and a predetermined angular velocity. By rotating with, a locus Tr as shown in FIG. 3 can be formed on the work 2. The plurality of closed region TrCs formed by the locus Tr are continuously formed by overlapping a part of the closed regions adjacent to each other. That is, the locus Tr shown in FIG. 3 is composed of the first section TrA shown by the broken line extending inside each of the plurality of closed region TrCs and the second section TrB shown by the solid line excluding the first section TrA. Become. Each first section TrA extends from the start point A, which is one end, to the end point B, which is the other end, and intersects the second section TrB at each of the start point A and the end point B. ..

The locus Tr is formed by the mirrors 23a and 23b of the eccentric mechanism 24 swinging as described above. That is, the eccentric mechanism 24 in the present embodiment scans the condensing spot SP moving on the work 2 while the emitting unit 25 is moving with respect to the work 2, and is closed surrounded by the locus Tr of the condensing spot SP. It can be understood as a scanning unit in which a plurality of region TrCs are continuously formed on the work 2.

The laser processing device 1 as described above is controlled by the control unit 30. The control unit 30 can use, for example, an integrated circuit such as a microcontroller, an IC (Integrated Circuit), an LSI (Large-scale Integrated Circuit), an ASIC (Application Specific Integrated Circuit), or an NC (Numerical Control) device. Further, when the NC device is used, the control unit 30 may use a machine learning device or may not use a machine learning device.

FIG. 4 is a block diagram including a control unit 30 of the laser processing apparatus 1. As shown in FIG. 4, the control unit 30 is connected to the motor 12M that drives the second guide member 12. The motor 12M is a motor that rotates the pinion gear of the second guide member 12 described above. The control unit 30 controls the operation of the motor 12M to move the second guide member 12 along the Y direction.

Further, the control unit 30 is connected to a motor 21M that drives the housing 21 of the laser irradiation device 20. The motor 21M is a motor that rotates the pinion gear of the rack and pinion mechanism that attaches the housing 21 to the second guide member 12 described above. The control unit 30 controls the operation of the motor 21M to move the housing 21, that is, the laser irradiation device 20 along the X direction.

Further, the control unit 30 is connected to the motor 24M of the eccentric mechanism 24. This motor 24M is a motor attached to the mirrors 23a and 23b described above, and is a stepping motor in this embodiment. The control unit 30 controls the motor 24M to make the plurality of mirrors 23a and 23b swing. Further, the control unit 30 controls the operation of the motor 24M to change the speed at which the plurality of mirrors 23a and 23b are swung. In this way, the control unit 30 rotates the condensing spot SP around the optical axis 25A of the condensing lens and changes the angular velocity of the condensing spot SP.

By the way, the locus Tr shown in FIG. 3 is a locus when the exiting portion 25 moves at a predetermined sweep speed v as described above. Therefore, when the sweep speed v is 0, the locus Tr becomes a circle as shown in FIG. 2, and the positional relationship between the start point A and the end point B in this case is, for example, the positional relationship as shown in FIG. It becomes. Here, in FIG. 5, a predetermined position of the locus is set as a reference point S. In the example of FIG. 5, the reference point S is a position where the condensing spot SP moves parallel to the sweep direction and to the opposite side. In this case, the position of the starting point A of the first segment TrA is a rotational position rotated from the reference point S by the angle theta _1, the position of the end point B of the first section TrA rotational position rotated from the starting point A by an angle theta ₂ be. The rotational position is a reference point S which is rotated by an angle theta ₃ from the end point B.

In the present embodiment, the control unit 30, from the reference point S to the start point A to control the motor 24M as the angular velocity of the focused spot SP is omega _1, the focused spot SP is rotated by an angle theta _1. After that, the motor 24M is controlled so that _{the angular velocity of the condensing spot SP becomes ω 2} slower than _{ω 1} from the start point A to the end point B, and the condensing spot SP rotates by an _{angle θ 2.} After that, the motor 24M is controlled so that _{the angular velocity of the condensing spot SP becomes ω 1} from the end point B to the reference point S. , The control unit 30 repeats this control cycle. That is, according to the control by the control unit 30, the condensing spot SP is scanned in the pattern of the angular velocity shown in FIG.

_{The angles θ 1} , the angle θ ₂ , and the angle θ _{3 with} respect to the reference point S as described above are the following equations (1) to (3) from the above angular velocities ω ₁ , ω _{2, sweep velocity v, and radius of gyration r.} ) Can be calculated.

Next, a laser processing method using the laser processing apparatus 1 of the present embodiment will be described.

FIG. 7 is a flowchart showing the laser processing method. As shown in FIG. 7, this laser machining method includes a mounting step SP1 and a machining step SP2.

(Placement process SP1)
First, in this step, the work 2 is placed on the main surface 10A of the stage 10 of the laser processing apparatus 1 so that the condensing spot SP can irradiate the work 2. In this step, the work 2 in which two metal plates are stacked may be placed on the main surface 10A as described above, or the work 2 in which the two metal plates are arranged is placed on the main surface 10A. You may. In the latter case, it is preferable to place the work 2 on the main surface 10A so that the condensing spot SP irradiates the area where the two arranged metal plates come into contact with each other. In the following, an example in which two metal plates 2A and 2B are overlapped as shown in FIG. 1 and the metal plates 2A and 2B are welded will be described.

(Processing process SP2)
This step is a step of moving the focused spot SP of the laser beam L on the work 2 to continuously form a plurality of closed region TrCs surrounded by the locus Tr of the focused spot SP on the work 2.

In this step, first, the light source 22 is operated by the control unit 30. As a result, the laser beam L is emitted from the emitting portion 25, and the condensing spot SP is irradiated on the metal plate 2A of the work 2. The power of the laser beam L in this embodiment is constant, and may be, for example, 1 kW. Further, the diameter of the condensing spot SP in the present embodiment is constant, and may be, for example, 800 μm.

Further, the control unit 30 controls the motor 21M and the motor 24M to move the exit unit 25 and the work 2 relatively along the X direction at a constant sweep speed v, and sets the condensing spot SP to a predetermined value. Scan at angular velocity. The sweep speed v may be, for example, 50 mm / s. As a result, the condensing spot SP draws the locus Tr shown in FIG. 3, and a plurality of closed region TrCs are continuously formed on the work 2.

By the way, as described above, the control unit 30 determines the condensing spot SP until the condensing spot SP rotates by an angle θ1 from the reference point S, that is, until the condensing spot SP reaches the start point A from the reference point S. Is scanned at an angular velocity of ω _1. Further, the control unit 30 sets the focusing _{spot SP at an angular velocity ω 1 until the focusing spot SP rotates from the angle θ 1} to the angle θ ₂ , that is, until the focusing spot SP reaches the end point A from the end point B. Scan at a slow angular velocity ω _2. Further, the control unit 30 scans the _{condensing spot SP at an angular velocity ω 1 until it rotates from the angle θ 2} to the angle θ ₃ , that is, until the condensing spot SP reaches the reference point S from the end point B. That is, when the control unit 30 forms a new closed region TrC, the control unit 30 slows the angular velocity of the focused spot SP during the period in which the focused spot SP passes through the first section TrA, which is a section within the already formed closed region TrC. Scan with ω _{2. Further, when forming a new closed region TrC, the control unit 30 performs the focused spot SP at a high angular velocity ω 1} during the period in which the focused spot SP passes through the second section TrB, which is a section other than the first section TrA. Scan. In this way, when forming a new closed region TrC, the control unit 30 scans the _{focused spot SP at a high angular velocity ω 1} during the period in which the focused spot SP passes through a region other than the already formed closed region TrC. That is, when forming a new closed region TrC, the control unit 30 controls the moving unit and the scanning unit so that the condensing spot SP passes through the already formed closed region TrC, and the already formed closed region TrC. The speed of the condensing spot SP moving on the work 2 during the period in which the condensing spot SP passes through the TrC moves on the work 2 in the period in which the condensing spot SP passes through a closed region TrC other than the already formed closed region TrC. The scanning unit is controlled so as to be slower than the speed of the focusing spot SP.

As described above, in this step, the angular velocity _{changes from ω 1} to ω ₂ as described above, so that when a new closed region TrC is formed, the condensing spot SP extends from the start point A to the end point B. The speed of the condensing spot SP moving on the work 2 during the period becomes slower than the speed of the condensing spot SP during the period of passing through other than the already formed closed region TrC. That is, it is required for the condensing spot SP to pass through the already formed closed region TrC as compared with the case where the condensing spot SP is scanned at an _{angular velocity ω 1} during the period of passing through the already formed closed region TrC. The time can be long. Here, the irradiation energy that the condensing spot SP irradiates the work 2 is proportional to the product of the power of the laser beam L in the condensing spot SP and the time required for the condensing spot SP to travel on the work 2. As described above, the power of the laser beam L forming the focused spot SP is constant. Therefore, as described above, when forming a new closed region TrC, the speed of the condensing spot SP moving on the work 2 during the period of passing through the already formed closed region TrC is slowed down, so that the speed of the condensing spot SP is already slowed down. Irradiating the closed region TrC as compared with the case where the speed of the condensing spot SP during the period of passing through the formed closed region TrC and the speed of the condensing spot SP during the period of passing through other than the closed region TrC are constant. The irradiation energy to be applied increases.

In this way, as shown in FIG. 3, a plurality of closed region TrCs surrounded by the locus Trs of the condensing spot SP are continuously formed on the work 2.

After drawing the locus Tr, the control unit 30 drives the motor 12M to move the second guide member 12 in the Y direction to move the laser irradiation device 20 in the Y direction, and again performs the processing step SP2. You may go. As a result, another locus can be drawn at a position deviated in the Y direction from the already formed locus Tr. That is, by driving the motor 12M after performing the machining step SP2, a plurality of loci Tr can be drawn on the work 2.

As described above, the laser processing apparatus 1 of the present embodiment moves the light source 22, the emission unit 25 that emits the laser beam L from the light source 22 toward the work 2, and the emission unit 25 with respect to the work 2. A closed region TrC surrounded by the locus Tr of the focused spot SP by scanning the focused spot SP of the laser beam L moving on the work 2 with the moving portion to be moved and the emitting portion 25 moving with respect to the work 2. The work 2 is provided with a scanning unit for continuously forming a plurality of scanning units and a control unit 30. Then, the control unit 30 scans the condensing spot SP so that the condensing spot SP passes through the already formed closed region TrC by controlling the moving unit and the scanning unit, and then the already formed closed area TrC. A new closed region TrC is formed by scanning the condensing spot SP so as to pass through a region other than the region TrC, and the scanning portion is controlled when the new closed region TrC is formed. The speed of the condensing spot SP moving on the work 2 during the period of passing through the closed region TrC is slower than the speed of the condensing spot SP moving on the work 2 during the period of passing through other than the already formed closed region TrC. do.

Further, the laser processing method of the present embodiment can be carried out by using the laser processing apparatus 1. In this laser processing method, the condensing spot SP of the laser beam L is moved on the work 2, and a plurality of closed region TrCs surrounded by the locus Tr of the condensing spot SP are continuously formed on the work 2 in the processing step SP2. It has. Then, in the processing step SP2, after scanning the condensing spot SP so as to pass through the already formed closed region TrC, the condensing spot SP is scanned so as to pass through other than the already formed closed region TrC. When forming a new closed region TrC and forming a new closed region TrC, the speed of the condensing spot SP moving on the work 2 during the period of passing through the already formed closed region TrC has already been formed. It is slower than the speed of the condensing spot SP moving on the work 2 during the period of passing through other than the closed region TrC.

If the speed of the condensing spot SP on the work 2 is slowed down as described above, the speed of the condensing spot SP moving on the work 2 during the period of passing through the already formed closed region TrC and other than the closed region TrC. The time for the condensing spot SP to pass through the already formed closed region TrC can be increased as compared with the case where the speed of the condensing spot SP moving on the work during the period of passing through the work is the same. In this embodiment, as described above, the light power of the condensing spot SP is constant. Therefore, the angular velocity of the condensing spot SP is slowed down to slow down the speed at which the condensing spot SP moves on the work 2, and the time required for the condensing spot SP to pass through the already formed closed region TrC. By lengthening, the work 2 has a larger amount of irradiation energy than the irradiation energy in the period in which the condensing spot SP passes through the already formed closed region TrC and in the period in which the condensing spot passes through other than the already formed closed region TrC. Large irradiation energy is applied. Therefore, the temperature of the closed region TrC is higher than that in the case where the average of the irradiation energy in the period of passing through the already formed closed region TrC and the average of the irradiation energy in the period of forming the closed region TrC are the same. Can be hot. Therefore, it is possible to suppress processing defects due to insufficient temperature during processing.

Further, in the laser processing apparatus 1 and the processing step SP2, the closed region TrC is preheated by forming the closed region TrC. If the work 2 is preheated in this way, even if a large irradiation energy as described above is subsequently applied to the closed region TrC, the temperature in the closed region TrC is suppressed from rising sharply, and the closed region TrC is subjected to. It can mitigate thermal shock. Further, in the case of the laser processing method and the laser processing apparatus 1 of the present embodiment, the average of the irradiation energy in the period of passing through the closed region TrC and the average of the irradiation energy in the period of forming the closed region TrC are the same. Comparing with the case, when the work 2 is heated to the same temperature and processed, in the former case, the light condensing that irradiates the work 2 during the period in which the condensing spot SP passes through a region other than the already formed closed region TrC. The average of the irradiation energies of the spots can be reduced, and the impact on the work during this period can be mitigated. As described above, according to the laser processing method and the laser processing apparatus 1 of the present embodiment, processing defects can be suppressed.

Although the present invention has been described above by taking the above-described embodiment as an example, the present invention is not limited thereto.

For example, in the above embodiment, when forming a new closed region TrC, the speed of the condensing spot SP moving on the work 2 in the period of passing through the closed region TrC is in the period of passing through other than the closed region TrC. An example in which the speed of the condensing spot SP moving on the work 2 is slower than that of the light condensing spot SP has been described. However, when forming a new closed region TrC, the average irradiation energy of the condensing spot SP that irradiates the work 2 during the period of passing through the closed region TrC irradiates the work 2 during the period of passing through other than the closed region TrC. If it is larger than the average of the irradiation energies of the condensing spot SP, the amount of heat applied to the closed region TrC can be increased as compared with the case where the average of the irradiation energies in both of these periods is the same. Can be hot.

Specifically, when forming a new closed region TrC, the power of the light of the focused spot SP during the period of passing through the closed region TrC is the power of the light of the focused spot SP during the period of passing through other than the closed region TrC. It may be larger than the power. By doing so, the irradiation energy applied to the closed region is increased as compared with the case where the light power of the focused spot SP is the same in both of these periods. Therefore, the work 2 can be heated to a high temperature. In this case, the output of the light source 22 may be increased by the control of the control unit 30. Further, the irradiation energy can be further increased by increasing the light power of the condensing spot SP and slowing down the angular velocity of the condensing spot SP.

Further, in the above embodiment, the example in which the exiting portion 25 moves with respect to the fixed work 2 has been described, but the work 2 and the emitting portion 25 may move relative to each other. For example, a moving unit that moves the work 2 with respect to the fixed emitting unit 25 may be configured.

Further, in the above embodiment, the angular velocity ω ₁ of the condensing spot SP during the period of passing through the closed region TrC is constant, and the angular velocity ω _{2 of the} condensing spot SP during the period of passing through the closed region TrC is also constant. .. However, when forming a new closed region TrC, the average speed of the condensing spot SP moving on the work 2 during the period of passing through the closed region TrC is on the work 2 during the period of passing through other than the closed region TrC. _{The value of ω 1} may be changed or the value of _{ω 2} may be changed as long as it is slower than the average speed of the condensing spot SP moving. In short, as described above, when forming a new closed region TrC, the average irradiation energy of the condensing spot SP that irradiates the work 2 during the period of passing through the closed region TrC is the period during which it passes through other than the closed region TrC. If it is larger than the average irradiation energy of the condensing spot SP that irradiates the work 2 in the above, the amount of heat applied to the closed region TrC by the condensing spot SP can be increased, and the work 2 can be heated to a high temperature.

Further, in the above embodiment, an example in which the work 2 is welded by the processing step SP2 has been described, but the work 2 may be cut or modified by the processing step SP2. By doing so, the work 2 can be cut or modified by raising the temperature of the work 2 while alleviating the thermal shock.

Further, the locus of the condensing spot SP drawn in the processing step SP2 is not limited to that shown in FIG. 3, and when the condensing spot passes through the closed region already formed when forming a new closed region, the condensing spot passes through the closed region. The locus may be such that a plurality of closed regions are continuously formed on the work. For example, the locus Tr2 as shown in FIG. 8 may be used. This locus Tr2 is a locus of a repeating pattern of the 8-shaped closed region drawn by the condensing spot SP passing through the already formed 8-shaped closed region. Alternatively, although not shown, it may be a locus of a repeating pattern of an ∞-shaped closed region.

Further, the control of the angular velocity by the control unit 30 described above is an example, and the angular velocity of the condensing spot may be controlled by another method. For example, a laser processing device is equipped with a camera capable of photographing the surface to be processed of the work. This camera outputs image data of the surface to be machined to the control unit. Further, the image data of the surface to be processed irradiated to the condensing spot is stored in advance in the memory connected to the control unit. According to such a configuration, the control unit can control the angular velocity by image recognition. Specifically, when the condensing spot reaches a locus forming a closed region, the camera images the surface to be processed irradiated on the condensing spot and outputs the captured image data to the control unit. .. The control unit compares the image data output from the camera with the image data stored in the memory, and when both image data match to the extent that the predetermined threshold value is not exceeded, the condensing spot SP is set at the start point A. You may judge that it has been reached. Then, the control unit may slow down the angular velocity of the condensing spot SP in this case. Further, when the two image data match again as described above, it may be determined that the condensing spot SP has reached the end point B, and the angular velocity of the condensing spot SP may be increased.

Further, the mirror described in the above embodiment may be a MEMS mirror. In this case, the eccentric mechanism 24 may be, for example, a piezo element or a magnetic field generating element.

According to the present invention, a laser processing method and a laser processing apparatus capable of suppressing processing defects are provided, and can be used in a field such as metal processing.

1 ... Laser processing device 2 ... Work 11 ... First guide member (moving part)
12 ... Second guide member (moving part)
20 ... Laser irradiation device 24 ... Eccentric mechanism (scanning unit)
25 ... Emission unit 30 ... Control unit A ... Start point B ... End point L ... Laser beam SP ... Condensing spot Tr ... Trajectory TrA ... First section TrB ...・ Second section TrC ・ ・ ・ Closed area

Claims (9)

A processing step of moving a focused spot of laser light on a work to continuously form a plurality of closed regions surrounded by loci of the focused spot on the work is provided.
In the processing step, the condensing spot is scanned so as to pass through the already formed closed region, and then the condensing spot is scanned so as to pass through a region other than the already formed closed region. Forming the closed region
When forming the new closed region, the average of the irradiation energies of the focused spot that irradiates the work during the period in which the focused spot passes through the already formed closed region is the already formed closed region. A laser processing method characterized in that it is larger than the average irradiation energy of the focused spot that irradiates the work during the period in which the focused spot passes through a region other than the region. When forming the new closed region, the average speed of the focused spots moving on the work during the period in which the focused spots pass through the already formed closed regions is the average of the speeds of the focused spots already formed. The laser processing method according to claim 1, wherein the laser processing method is slower than the average speed of the focused spots moving on the work during the period in which the focused spots pass other than the closed region. When forming a new closed region, the power of the laser beam during the period in which the focused spot passes through the already formed closed region allows the focused spot to pass through a region other than the already formed closed region. The laser processing method according to claim 1 or 2, wherein the power of the laser beam is larger than that of the laser beam during the period. The laser processing method according to any one of claims 1 to 3, wherein the work is welded by the processing step. The laser processing method according to any one of claims 1 to 3, wherein the work is cut by the processing step. The laser processing method according to any one of claims 1 to 3, wherein the work is modified by the processing step. Light source and
An exit portion that emits laser light from the light source toward the work,
A moving part that moves the emitting part and the work relative to each other,
The focused spot of the laser beam moving on the work is scanned while the emitting portion and the work are relatively moving, and a closed region surrounded by the locus of the focused spot is continuously formed on the work. Multiple scanning units and
Control unit and
With
By controlling the moving unit and the scanning unit, the control unit scans the condensing spot so that the condensing spot passes through the closed region that has already been formed, and then the condensing spot is already formed. When the focused spot is scanned so as to pass through a region other than the closed region to form a new closed region and the new closed region is formed, at least one of the light source and the scanning portion is controlled. As a result, the average irradiation energy of the condensing spot that irradiates the work during the period in which the condensing spot passes through the already formed closed region is such that the condensing spot passes through a region other than the already formed closed region. A laser processing apparatus characterized in that the irradiation energy of the condensing spot for irradiating the work during the period is larger than the average of the irradiation energies. When the control unit forms a new closed region, the control unit controls the scanning unit to move on the work during the period in which the condensing spot passes through the already formed closed region. It is characterized in that the average of the speeds of the light spots is slower than the average of the speeds of the focused spots moving on the work during the period in which the focused spots pass other than the already formed closed region. The laser processing apparatus according to claim 7. By controlling the light source when forming the new closed region, the control unit has already formed the power of the laser beam during the period in which the focused spot passes through the already formed closed region. The laser processing apparatus according to claim 7 or 8, wherein the power of the laser beam is increased in a period other than the closed region in which the focused spot passes.

Images