Laser processing equipment

Abstract

To enhance the machining quality and machining speed of work-piece.SOLUTION: A laser machining head 20 emits a first laser beam L1 of short wavelength, and a second laser beam L2 of long wavelength. A dichroic mirror 26 overlaps the first laser beam L1 and the second laser beam L2. An fθ lens 27 condenses the first laser beam L1 and the second laser beam L2 overlapped by the dichroic mirror 26 toward work-piece W. A first adjusting mechanism 24 adjusts an incident position of the first laser beam L1 to the dichroic mirror 26.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a laser processing apparatus.

Background Art

[0002] Patent Document 1 discloses a laser processing optical apparatus including an optical system that guides two lasers having different wavelengths onto a coaxial optical path and superimposes them, and a condenser lens that condenses the output beams of the two lasers superimposed on the coaxial optical path onto a workpiece (work to be processed).

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, although the laser light with a short wavelength has a high laser absorption rate for workpieces made of high-reflectivity materials such as copper and aluminum, the maximum output of the laser light is low, resulting in a slow processing speed.

[0005] On the other hand, although the maximum output of the laser light with a long wavelength is higher than that of the laser light with a short wavelength, the laser absorption rate for workpieces made of high-reflectivity materials is low. Therefore, it is difficult to keep the melting depth of the workpiece constant with the laser light having a long wavelength, and there is a risk of deterioration in processing quality.

[0006] The present invention has been made in view of such points, and its object is to improve the processing quality and processing speed of workpieces.

Means for Solving the Problems

[0007] The first invention is a laser processing apparatus for processing a workpiece by emitting laser light, comprising: a first laser oscillator that emits a first laser beam; a second laser oscillator that emits a second laser beam having a longer wavelength than the first laser beam; and a laser processing head that emits the first laser beam and the second laser beam incident from the first and second laser oscillators toward the workpiece, wherein the laser processing head comprises: a first collimating lens that parallelizes the first laser beam; a second collimating lens that parallelizes the second laser beam; a first optical member that superimposes the first and second laser beams that have passed through the first and second collimating lenses; a second optical member that focuses the first and second laser beams superimposed by the first optical member toward the workpiece; and a first adjustment mechanism that adjusts the incident position of the first laser beam toward the first optical member to relatively change the emission position of the first laser beam toward the second laser beam. The laser processing system includes a detection unit that detects data indicating the melting state at the processing position of the workpiece, and a control unit that controls the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit, wherein the detection unit includes a first detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the first laser beam, and by oscillating the first laser oscillator while stopping the second laser oscillator, the first laser beam is emitted from the laser processing head, the first detection unit detects the amount of scattered light of the first laser beam reflected by the workpiece, and the control unit causes the second laser oscillator to oscillate and emit the second laser beam from the laser processing head to the processing position of the workpiece if the amount of scattered light detected by the first detection unit is lower than a predetermined threshold, It is characterized by the following:

[0009] In this way, by adjusting the incident position of the first laser beam on the first optical element and relatively changing the emission position of the first laser beam relative to the second laser beam, the processing quality and processing speed of the workpiece can be improved. Furthermore, the detection unit detects data indicating the melting state at the workpiece processing location. Based on the data detected by the detection unit, the laser beam emission position and timing can be controlled. Additionally, by first roughening the surface of the workpiece with a short-wavelength first laser beam, and then determining that the workpiece has melted based on the amount of scattered light from the first laser beam detected by the first detection unit, the workpiece can be finished with a long-wavelength second laser beam, thereby improving the processing quality and speed of the workpiece.

[0020] The 2 The invention is A laser processing apparatus for processing a workpiece by emitting laser light, comprising: a first laser oscillator that emits a first laser beam; a second laser oscillator that emits a second laser beam having a longer wavelength than the first laser beam; and a laser processing head that emits the first laser beam and the second laser beam incident from the first laser oscillator and the second laser oscillator onto the workpiece, wherein the laser processing head includes a first collimating lens that parallelizes the first laser beam, a second collimating lens that parallelizes the second laser beam, and the first laser beam and the front laser beam that have passed through the first collimating lens and the second collimating lens. The laser processing device comprises a first optical member for superimposing a second laser beam, a second optical member for focusing the first and second laser beams superimposed by the first optical member toward the workpiece, and a first adjustment mechanism for adjusting the incident position of the first laser beam toward the first optical member to relatively change the emission position of the first laser beam toward the second laser beam; a detection unit for detecting data indicating the melting state at the processing position of the workpiece; and a control unit for controlling the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit. The detection unit includes a second detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the second laser beam. The first laser beam and the second laser beam are emitted from the laser processing head by oscillating the first laser oscillator and the second laser oscillator. The second detection unit detects the amount of scattered light of the second laser beam reflected by the workpiece. The control unit controls the operation of the second laser oscillator so as to gradually or stepwise increase the output of the second laser beam when the amount of scattered light detected by the second detection unit is lower than a predetermined threshold.

[0021] The 2 In this invention, In this way, by adjusting the incidence position of the first laser beam onto the first optical element and relatively changing the emission position of the first laser beam relative to the second laser beam, the processing quality and processing speed of the workpiece can be improved. Furthermore, data indicating the melting state at the workpiece processing position is detected by the detection unit. Based on the data detected by the detection unit, the laser beam emission position and emission timing can be controlled.After emitting a second long-wavelength laser beam at low power, the second detection unit determines that the workpiece has melted based on the amount of scattered light from the second laser beam detected by the second detection unit. By increasing the output of the second laser beam to process the workpiece, the processing quality and processing speed of the workpiece can be improved.

[0022] The 3 The invention is A laser processing apparatus for processing a workpiece by emitting laser light, comprising: a first laser oscillator that emits a first laser beam; a second laser oscillator that emits a second laser beam having a longer wavelength than the first laser beam; and a laser processing head that emits the first laser beam and the second laser beam incident from the first laser oscillator and the second laser oscillator onto the workpiece, wherein the laser processing head includes a first collimating lens that parallelizes the first laser beam, a second collimating lens that parallelizes the second laser beam, and the first laser beam and the front laser beam that have passed through the first collimating lens and the second collimating lens. The laser processing device comprises a first optical member for superimposing a second laser beam, a second optical member for focusing the first and second laser beams superimposed by the first optical member toward the workpiece, and a first adjustment mechanism for adjusting the incident position of the first laser beam toward the first optical member to relatively change the emission position of the first laser beam toward the second laser beam; a detection unit for detecting data indicating the melting state at the processing position of the workpiece; and a control unit for controlling the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit. The detection unit includes a second detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the second laser beam. The first laser beam and the second laser beam are emitted from the laser processing head by oscillating the first laser oscillator and the second laser oscillator. The second detection unit detects the amount of scattered light from the second laser beam reflected by the workpiece. The control unit controls the operation of the laser processing head so that the first laser beam is emitted at the processing position of the workpiece when the amount of scattered light detected by the second detection unit is higher than a predetermined threshold.

[0023] The 3 In this invention, In this way, by adjusting the incidence position of the first laser beam onto the first optical element and relatively changing the emission position of the first laser beam relative to the second laser beam, the processing quality and processing speed of the workpiece can be improved. Furthermore, data indicating the melting state at the workpiece processing position is detected by the detection unit. Based on the data detected by the detection unit, the laser beam emission position and emission timing can be controlled. After emitting a long-wavelength second laser beam onto the workpiece, the second detection unit determines that the workpiece is not sufficiently melted based on the amount of scattered light from the second laser beam detected. By emitting a short-wavelength first laser beam onto the workpiece at the processing position, the melting of the workpiece can be promoted.

[0024] The 4 The invention is A laser processing apparatus for processing a workpiece by emitting laser light, comprising: a first laser oscillator that emits a first laser beam; a second laser oscillator that emits a second laser beam having a longer wavelength than the first laser beam; and a laser processing head that emits the first laser beam and the second laser beam incident from the first laser oscillator and the second laser oscillator onto the workpiece, wherein the laser processing head includes a first collimating lens that parallelizes the first laser beam, a second collimating lens that parallelizes the second laser beam, and the first laser beam and the front laser beam that have passed through the first collimating lens and the second collimating lens. The laser processing device comprises a first optical member for superimposing a second laser beam, a second optical member for focusing the first and second laser beams superimposed by the first optical member toward the workpiece, and a first adjustment mechanism for adjusting the incident position of the first laser beam toward the first optical member to relatively change the emission position of the first laser beam toward the second laser beam; a detection unit for detecting data indicating the melting state at the processing position of the workpiece; and a control unit for controlling the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit. The detection unit includes a second detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the second laser beam. The first laser beam and the second laser beam are emitted from the laser processing head by oscillating the first laser oscillator and the second laser oscillator. The second detection unit detects the amount of scattered light of the second laser beam reflected by the workpiece. The control unit controls the operation of the first laser oscillator so as to gradually or stepwise increase the output of the first laser beam when the amount of scattered light detected by the second detection unit is higher than a predetermined threshold.

[0025] In the invention of 4 , after the second laser beam with a long wavelength is emitted to the workpiece, it is determined based on the amount of scattered light of the second laser beam detected by the second detection unit that the workpiece is not sufficiently melted, and the preheating of the workpiece is sufficiently performed by further increasing the output of the first laser beam with a short wavelength, and the melting of the workpiece can be promoted. In this way, by adjusting the incidence position of the first laser beam onto the first optical element and relatively changing the emission position of the first laser beam relative to the second laser beam, the processing quality and processing speed of the workpiece can be improved. Furthermore, data indicating the melting state at the workpiece processing position is detected by the detection unit. Based on the data detected by the detection unit, the laser beam emission position and emission timing can be controlled.

[0026] In the invention of 5 , A laser processing apparatus for processing a workpiece by emitting laser light, comprising: a first laser oscillator that emits a first laser beam; a second laser oscillator that emits a second laser beam having a longer wavelength than the first laser beam; and a laser processing head that emits the first laser beam and the second laser beam incident from the first laser oscillator and the second laser oscillator onto the workpiece, wherein the laser processing head includes a first collimating lens that parallelizes the first laser beam, a second collimating lens that parallelizes the second laser beam, and the first laser beam and the front laser beam that have passed through the first collimating lens and the second collimating lens. The laser processing device comprises a first optical member for superimposing a second laser beam, a second optical member for focusing the first and second laser beams superimposed by the first optical member toward the workpiece, and a first adjustment mechanism for adjusting the incident position of the first laser beam toward the first optical member to relatively change the emission position of the first laser beam toward the second laser beam; a detection unit for detecting data indicating the melting state at the processing position of the workpiece; and a control unit for controlling the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit. the detection unit includes a second detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the second laser beam. By oscillating the first laser oscillator and the second laser oscillator, the first laser beam and the second laser beam are emitted from the laser processing head. In the second detection unit, the amount of scattered light of the second laser beam reflected by the workpiece is detected. The control unit controls the operation of the second laser oscillator so as to stop the output of the second laser beam when the amount of scattered light detected by the second detection unit is higher than a predetermined upper limit value.

[0027] In the invention of 5 , In this way, by adjusting the incidence position of the first laser beam onto the first optical element and relatively changing the emission position of the first laser beam relative to the second laser beam, the processing quality and processing speed of the workpiece can be improved. Furthermore, data indicating the melting state at the workpiece processing position is detected by the detection unit. Based on the data detected by the detection unit, the laser beam emission position and emission timing can be controlled. it is possible to prevent the laser processing head from being damaged by irradiating the laser processing head with the scattered light of the high-output second laser beam reflected by the workpiece.

Advantages of the Invention

[0030] According to the present invention, the processing quality and processing speed of the workpiece can be improved.

Brief Description of the Drawings

[0031] [Figure 1] It is a side view showing a schematic configuration of a laser processing apparatus according to Embodiment 1. [Figure 2] It is a graph showing the relationship between the wavelength and reflectivity of a laser beam. [Figure 3] It is a plan view showing a state where the first laser beam is emitted at the laser start position. [Figure 4] ​This is a plan view showing the state after the second laser beam has been emitted from the laser starting position. [Figure 5] This is a plan view showing the state of the workpiece during laser processing. [Figure 6] This is a side view showing the schematic configuration of the laser processing apparatus according to this second embodiment. [Figure 7] This graph shows the relationship between the scattered light intensity of the second laser beam and the elapsed time. [Modes for carrying out the invention]

[0032] Embodiments of the present invention will be described below with reference to the drawings. The following description of preferred embodiments is essentially illustrative and is not intended to limit the present invention, its applications, or its uses.

[0033] Embodiment 1 As shown in Figure 1, the laser processing apparatus 1 comprises a first laser oscillator 11, a second laser oscillator 12, a first transmission fiber 15, a second transmission fiber 16, a laser processing head 20, a robot 2, and a control unit 5.

[0034] The first laser oscillator 11 outputs a first laser beam L1 based on a command from the control unit 5. The first laser beam L1 is a short-wavelength laser beam. The short-wavelength first laser beam L1 is a blue laser beam or a green laser beam with a wavelength of 600 nm or less (for example, 266 nm to 600 nm).

[0035] The first laser oscillator 11 and the laser processing head 20 are connected by a first transmission fiber 15. The first laser beam L1 is transmitted from the first laser oscillator 11 to the laser processing head 20 via the first transmission fiber 15.

[0036] The second laser oscillator 12 outputs a second laser beam L2 based on a command from the control unit 5. The second laser beam L2 is a long-wavelength laser beam with a longer wavelength than the first laser beam L1. The long-wavelength second laser beam L2 is an infrared laser beam with a wavelength of 800 nm or more (for example, around 800 nm to 16000 nm).

[0037] The second laser oscillator 12 and the laser processing head 20 are connected by a second transmission fiber 16. The second laser light L2 is transmitted from the second laser oscillator 12 to the laser processing head 20 via the second transmission fiber 16.

[0038] The laser processing head 20 emits the first laser beam L1 and the second laser beam L2, which are incident from the first transmission fiber 15 and the second transmission fiber 16, to the workpiece W.

[0039] The laser processing head 20 includes a first collimating lens 21, a second collimating lens 22, a first mirror 23, a first adjustment mechanism 24, a second adjustment mechanism 25, a dichroic mirror 26 (first optical element), an fθ lens 27 (second optical element), and a first detection unit 28.

[0040] The first collimating lens 21 parallelizes the first laser beam L1 emitted from the exit end of the first transmission fiber 15. The second collimating lens 22 parallelizes the second laser beam L2 emitted from the exit end of the second transmission fiber 16. The first mirror 23 reflects the first laser beam L1, which has been parallelized by the first collimating lens 21, and guides it to the first adjustment mechanism 24.

[0041] The first adjustment mechanism 24 is composed of a two-axis MEMS (Micro Electro Mechanical Systems) mirror. The first adjustment mechanism 24 further reflects the first laser beam L1 reflected by the first mirror 23 and guides it to the dichroic mirror 26. The first adjustment mechanism 24 changes the incident position of the first laser beam L1 on the dichroic mirror 26 by changing the angle of the mirror. The first adjustment mechanism 24 may also be configured using a two-axis galvanometer (galvanometer mirror).

[0042] The second adjustment mechanism 25 is composed of a two-axis MEMS mirror. The second adjustment mechanism 25 reflects the second laser beam L2, which has been parallelized by the second collimating lens 22, and guides it to the dichroic mirror 26. The second adjustment mechanism 25 changes the incident position of the second laser beam L2 on the dichroic mirror 26 by changing the angle of the mirror. The second adjustment mechanism 25 may also be configured using a two-axis galvanometer.

[0043] The dichroic mirror 26 transmits the second laser beam L2 and reflects the first laser beam L1. The dichroic mirror 26 superimposes the first laser beam L1 and the second laser beam L2 and guides them to the fθ lens 27.

[0044] The fθ lens 27 focuses the first laser beam L1 and the second laser beam L2 at their respective incident positions so that they become beams that are incident perpendicularly to the surface (image plane) of the workpiece W. The first laser beam L1 and the second laser beam L2 focused by the fθ lens 27 are emitted to the workpiece W as parallel light (in other words, parallel light whose principal rays are parallel to the optical axis).

[0045] Here, the incident positions of the first laser beam L1 and the second laser beam L2 on the fθ lens 27 are moved by changing the angles of the first adjustment mechanism 24 and the second adjustment mechanism 25, respectively. This allows the first adjustment mechanism 24 and the second adjustment mechanism 25 to relatively change the emission positions of the first laser beam L1 and the second laser beam L2 on the workpiece W.

[0046] Furthermore, by moving the first collimating lens 21 and the second collimating lens 22 in the optical axis direction, the beam diameters of the first laser beam L1 and the second laser beam L2 can be increased or decreased, respectively.

[0047] The first detection unit 28 is composed of, for example, a photodiode. The first detection unit 28 detects data indicating the melting state at the processing position of the workpiece W. Here, the data indicating the melting state is the amount of scattered light from the first laser beam L1 reflected by the workpiece W.

[0048] A first filter 29 is placed between the first detection unit 28 and the workpiece W. The first filter 29 blocks the scattered light of the second laser beam L2 reflected by the workpiece W, while allowing the scattered light of the first laser beam L1 to pass through.

[0049] The first detection unit 28 detects the amount of scattered light from the first laser beam L1 that has passed through the first filter 29. The detection result from the first detection unit 28 is sent to the control unit 5.

[0050] The control unit 5 determines that the workpiece W has been sufficiently preheated by the first laser beam L1 when the amount of scattered light from the first laser beam L1 is less than a predetermined threshold.

[0051] Specifically, the amount of scattered light from the first laser beam L1 changes depending on the melting state of the workpiece W surface. For example, if the surface of the workpiece W is not sufficiently preheated by the first laser beam L1 and the amount of melted workpiece W is small, the amount of scattered light from the first laser beam L1 will be large. On the other hand, if the surface of the workpiece W is sufficiently preheated by the first laser beam L1 and the amount of melted workpiece W is large, the amount of scattered light from the first laser beam L1 will be small.

[0052] Robot 2 has a robotic arm 3. A laser processing head 20 is attached to the tip of the robotic arm 3. The robotic arm 3 has multiple joints 4.

[0053] Based on commands from the control unit 5, the robot 2 moves the laser processing head 20 along a predetermined processing direction, changing the position of the laser processing head 20 relative to the workpiece W. This changes the positions of the first laser beam L1 and the second laser beam L2 relative to the workpiece W, thereby performing laser processing.

[0054] The control unit 5 is connected to the first laser oscillator 11, the second laser oscillator 12, the laser processing head 20, and the robot 2. The control unit 5 controls the operation of the first laser oscillator 11, the second laser oscillator 12, the laser processing head 20, and the robot 2.

[0055] In addition to controlling the movement speed of the laser processing head 20, the control unit 5 also has functions to control the start and stop of the output of the first laser beam L1 and the second laser beam L2, and the output intensity of the first laser beam L1 and the second laser beam L2. Although the control unit 5 is shown as a single unit here, it may be configured as multiple units.

[0056] The workpiece W has a first member W1 and a second member W2. The first member W1 and the second member W2 are formed in a plate shape. The first member W1 is superimposed on the upper surface of the second member W2.

[0057] Workpiece W is composed of a highly reflective material with low laser absorption. Specifically, as shown in Figure 2, the reflectivity of laser light differs depending on the material of workpiece W. For example, using infrared laser light with a long wavelength of 800 nm or more as a reference, copper (Cu), aluminum (Al), gold (Au), and silver (Ag) have a higher reflectivity (%) at the wavelength of laser light compared to iron (Fe), meaning they are highly reflective materials with low laser absorption. On the other hand, iron (Fe) has a relatively low reflectivity (%) at the wavelength of laser light, meaning it is a low-reflectivity material with high laser absorption.

[0058] Therefore, in this embodiment, the workpiece W is made of copper, which is a highly reflective material with low laser absorption. Alternatively, the workpiece W may be made of gold or silver.

[0059] <Operation of the laser processing machine> Incidentally, the short-wavelength first laser beam L1 has a high laser absorption rate for workpieces W made of highly reflective materials such as copper, but its maximum laser output is low. Therefore, in order to obtain the required weld bead width, the beam diameter must be increased, but this reduces the power density, so the processing speed must be slowed down.

[0060] On the other hand, the long-wavelength second laser beam L2 has a higher maximum output than the short-wavelength first laser beam L1, but it has a lower laser absorption rate for the highly reflective workpiece W. Therefore, it is difficult to maintain a constant penetration depth of the workpiece W with the long-wavelength second laser beam L2, which may lead to a decrease in processing quality.

[0061] Therefore, in this embodiment, the processing quality and processing speed of the workpiece W can be improved by devising the emission positions of the first laser beam L1 and the second laser beam L2.

[0062] As shown in Figure 3, the laser processing head 20 emits a short-wavelength first laser beam L1 to the workpiece W. At the laser start position, the laser processing head 20 emits the short-wavelength first laser beam L1 in a pulsed manner. In this way, even though the first laser beam L1 has a low power density, by repeatedly emitting it in a pulsed manner to increase the total output, the workpiece W is sufficiently preheated. As a result, a preheated area 30 is formed at the laser start position where a portion of the workpiece W is molten.

[0063] Specifically, the laser processing head 20 emits a first laser beam L1, which has a high laser absorption rate for highly reflective materials, onto the surface of the workpiece W in advance, thereby performing surface modification such as oxidizing the surface of the workpiece W or partially melting the surface of the workpiece W beforehand.

[0064] The first detection unit 28 detects the amount of scattered light from the short-wavelength first laser beam L1 at the laser start position. The detection result from the first detection unit 28 is sent to the control unit 5. The control unit 5 determines that the workpiece W has been sufficiently preheated and the preheating unit 30 has been formed when the amount of scattered light from the first laser beam L1 is less than a predetermined threshold.

[0065] As shown in Figure 4, the laser processing head 20 changes the emission position of the first laser beam L1 by adjusting the angle of the first adjustment mechanism 24 (see Figure 1). Specifically, the first laser beam L1 is emitted forward in the processing direction (to the left in Figure 4) from the laser start position. A preheating section 30 is formed on the workpiece W along the emission path of the first laser beam L1.

[0066] The laser processing head 20 emits a second laser beam L2 at the laser starting position. Since the laser starting position is preheated by the first laser beam L1, the second laser beam L2 is easily absorbed by the workpiece W. A molten pool 31 is formed at the laser starting position by the second laser beam L2.

[0067] Specifically, when the amount of scattered light from the first laser beam L1 is less than a predetermined threshold, the laser processing head 20 determines that the workpiece W has been sufficiently preheated and that the preheating section 30 has been formed. The laser processing head 20 then immediately follows the portion of the workpiece W whose surface has been modified by the short-wavelength first laser beam L1, which has a high laser absorption rate for the workpiece W made of high reflectivity material, and emits a long-wavelength second laser beam L2 with high power density. This makes it easier for the second laser beam L2, which has a low laser absorption rate for the workpiece W made of high reflectivity material, to be absorbed by the workpiece W made of high reflectivity material.

[0068] As shown in Figure 5, the laser processing apparatus 1 moves the laser processing head 20 in the processing direction. The laser processing head 20 continuously emits a first laser beam L1 and a second laser beam L2 onto the workpiece W.

[0069] The laser processing head 20 emits a first laser beam L1, which has a high laser absorption rate for highly reflective materials, onto the surface of the workpiece W in advance. The emission of the first laser beam L1 preheats the workpiece W, forming a preheating section 30.

[0070] The laser processing head 20 emits a second laser beam L2 with high power density to the preheating section 30 of the workpiece W. This makes the second laser beam L2 more easily absorbed by the workpiece W, allowing the molten pool 31 to be created in a short time. When the molten pool 31 solidifies, a weld bead 32 is formed, and the first member W1 and the second member W2 of the workpiece W are welded together.

[0071] In this manner, the laser processing head 20 forms a preheating section 30 by emitting at least a portion of the first laser beam L1 ahead of the second laser beam L2 in the direction of movement, thereby making the second laser beam L2 more easily absorbed. The laser processing head 20 modifies the surface of the workpiece W with the first laser beam L1 prior to the second laser beam L2, and then laser processes the surface of the workpiece W by emitting the second laser beam L2. This improves the processing quality and processing speed of the workpiece.

[0072] Here, even while the laser processing head 20 is moving, the first detection unit 28 detects the amount of scattered light from the short-wavelength first laser beam L1, so that after the preheating unit 30 is sufficiently formed, the long-wavelength second laser beam L2 can be emitted to the preheating unit 30 in a timely and stable manner.

[0073] As shown in Figure 5, the laser processing head 20 emits the first laser beam L1 and the second laser beam L2 to the workpiece W, and adjusts the angle of the first adjustment mechanism 24 (see Figure 1) to change the emission position of the first laser beam L1 relative to the second laser beam L2, so that at least a portion of the first laser beam L1 is emitted forward in the processing direction (movement direction) compared to the second laser beam L2. The first laser beam L1 is emitted forward in the processing direction compared to the second laser beam L2, and the second laser beam L2 is emitted at least following the first laser beam L1 in the processing direction.

[0074] More specifically, the laser processing head 20 changes the emission position of the first laser beam L1 between a forward position and a backward position. In the forward position, the first laser beam L1 is positioned in front of the second laser beam L2 in the processing direction. In the backward position, the first laser beam L1 is positioned behind the second laser beam L2 in the processing direction.

[0075] In this way, at the forward position, the surface of the workpiece W is roughened by partially melting it as a surface modification using the first short-wavelength laser beam L1, and then the workpiece W is finished with the second long-wavelength laser beam L2, thereby improving the processing quality and processing speed of the workpiece W.

[0076] Furthermore, at the rear position, by emitting the short-wavelength first laser beam L1 behind the long-wavelength second laser beam L2, the processed surface of the workpiece W processed by the second laser beam L2 can be cleaned. For example, by emitting the first laser beam L1 onto the weld bead 32 that has solidified after welding with the second laser beam L2, slag can be removed and the appearance of the weld bead 32 can be made smooth. Also, at the laser termination position, by emitting the first laser beam L1 behind the second laser beam L2, the generation of craters can be suppressed.

[0077] In this embodiment, the case of laser welding the workpiece W has been described, but it can also be applied to the case of laser cutting the workpiece W. For example, by emitting the first laser beam L1 onto the cut surface cut by the second laser beam L2, the cut surface can be made cleaner.

[0078] Embodiment 2 In the following description, the same reference numerals are used for parts that are the same as those in Embodiment 1, and only the differences will be described.

[0079] As shown in Figure 6, the laser processing head 20 has a first detection unit 28 and a second detection unit 38. The first detection unit 28 detects the amount of scattered light from the short-wavelength first laser beam L1 that has been reflected by the workpiece W and passed through the first filter 29. The detection result from the first detection unit 28 is sent to the control unit 5.

[0080] The second detection unit 38 is composed of, for example, a photodiode. The second detection unit 38 detects data indicating the melting state at the processing position of the workpiece W. Here, the data indicating the melting state detected by the second detection unit 38 is the amount of scattered light from the long-wavelength second laser beam L2 reflected by the workpiece W.

[0081] A second filter 39 is placed between the second detection unit 38 and the workpiece W. The second filter 39 blocks the scattered light of the short-wavelength first laser beam L1 reflected by the workpiece W, while allowing the scattered light of the long-wavelength second laser beam L2 to pass through.

[0082] The second detection unit 38 detects the amount of scattered light from the long-wavelength second laser beam L2 that has passed through the second filter 39. The detection result from the second detection unit 38 is sent to the control unit 5.

[0083] The control unit 5 controls the operation of the second laser oscillator 12 to increase the output of the second laser beam L2 when the amount of scattered light from the long-wavelength second laser beam L2 detected by the second detection unit 38 is less than a predetermined threshold.

[0084] Specifically, the amount of scattered light from the long-wavelength second laser beam L2 changes depending on the melting state of the workpiece W's surface. For example, if the surface of the workpiece W is not sufficiently melted by the second laser beam L2, the amount of scattered light from the second laser beam L2 increases. On the other hand, if the surface of the workpiece W is sufficiently melted by the second laser beam L2, the amount of scattered light from the second laser beam L2 decreases.

[0085] Therefore, after emitting a long-wavelength second laser beam L2 at low power, the second detection unit 38 determines that the workpiece W has melted based on the amount of scattered light from the long-wavelength second laser beam L2 detected by the second detection unit 38. By gradually increasing the output of the second laser beam L2 in stages to process the workpiece W, sputter generation can be suppressed, and the processing quality and processing speed of the workpiece W can be improved.

[0086] -Modification 1 of Embodiment 2- In the laser processing apparatus 1 shown in Figure 6, the control unit 5 controls the operation of the laser processing head 20 so that when the amount of scattered light from the long-wavelength second laser beam L2 detected by the second detection unit 38 is higher than a predetermined threshold, the first laser beam L1 is emitted to the processing position of the workpiece W.

[0087] As a result, after emitting a long-wavelength second laser beam L2 to the workpiece W, the second detection unit 38 determines that the workpiece W is not sufficiently melted based on the amount of scattered light from the long-wavelength second laser beam L2 detected by the second detection unit 38. By emitting a short-wavelength first laser beam L1 to the processing position of the highly reflective workpiece W, the melting of the highly reflective workpiece W can be promoted.

[0088] -Modification 2 of Embodiment 2- In the laser processing apparatus 1 shown in Figure 6, the control unit 5 controls the operation of the first laser oscillator 11 so as to gradually or stepwise increase the output of the short-wavelength first laser beam L1 when the amount of scattered light from the long-wavelength second laser beam L2 detected by the second detection unit 38 is higher than a predetermined threshold.

[0089] As a result, after emitting a long-wavelength second laser beam L2 to a workpiece W made of highly reflective material, the second detection unit 38 determines that the workpiece W is not sufficiently melted based on the amount of scattered light from the long-wavelength second laser beam L2 detected by the second detection unit 38. Then, by emitting a short-wavelength first laser beam L1 at high power to sufficiently preheat the workpiece W, sputtering can be suppressed and the melting of the highly reflective workpiece W can be promoted.

[0090] -Modification 3 of Embodiment 2- In the laser processing apparatus 1 shown in Figure 6, the control unit 5 controls the operation of the second laser oscillator 12 so as to stop the output of the second laser beam L2 when the amount of scattered light of the long-wavelength second laser beam L2 detected by the second detection unit 38 is higher than a predetermined upper limit (see Figure 7).

[0091] This prevents the scattered light of the high-power second laser beam L2 reflected by the workpiece W from irradiating the laser processing head 20, thus preventing damage to the laser processing head 20.

[0092] Furthermore, the first laser oscillator 11 can be kept oscillating and preheating the workpiece W with the short-wavelength first laser light L1 to promote the melting of the highly reflective workpiece W.

[0093] Other embodiments The above embodiment may also have the following configuration.

[0094] In this embodiment, the first detection unit 28 and the second detection unit 38 are composed of photodiodes, but the embodiment is not limited to this configuration. For example, a camera, a temperature sensor, an optical interferometer, etc., may be used as the first detection unit 28 and the second detection unit 38.

[0095] For example, when using a camera, the data indicating the melting state of the workpiece W is image data of the contour of the preheating section 30 or molten pool 31 formed at the processing position of the workpiece W. Then, if the outer diameter of the preheating section 30 or molten pool 31 is greater than a predetermined threshold (for example, the beam diameter of the second laser beam L2), it can be determined that the workpiece W is sufficiently melted.

[0096] Furthermore, when using a temperature sensor, the data indicating the molten state of the workpiece W is the temperature at the processing location of the workpiece W. If the temperature at the processing location of the workpiece W is greater than a predetermined threshold (for example, the melting point of the workpiece W), it can be determined that the workpiece W is sufficiently molten.

[0097] Furthermore, when using an optical interferometer, the data indicating the molten state of the workpiece W is the penetration depth of the keyhole in the molten pool 31 formed at the processing position of the workpiece W. If the keyhole penetration depth is not very deep, the surface vibration of the molten pool 31 is measured. Then, if the keyhole penetration depth or the surface vibration of the molten pool 31 is greater than a predetermined threshold, it can be determined that the workpiece W is sufficiently molten.

[0098] In this embodiment, the robot 2 moves the laser processing head 20 to change its position relative to the workpiece W, but the embodiment is not limited to this. For example, the workpiece W may be mounted on a moving table (not shown), and the workpiece W may be moved relative to the laser processing head 20.

[0099] Alternatively, the laser processing head 20 and the mobile table on which the workpiece W is mounted may be moved relative to each other, and the first laser beam L1 and the second laser beam L2 may be moved relative to the workpiece W to perform processing.

[0100] In this embodiment, a configuration has been described in which a short-wavelength first laser beam L1 and a long-wavelength second laser beam L2 are emitted from a single laser processing head 20, but the embodiment is not limited to this configuration. For example, a configuration in which a laser processing head that emits the short-wavelength first laser beam L1 and a laser processing head that emits the long-wavelength second laser beam L2 are provided separately may also be used. [Industrial applicability]

[0101] As described above, the present invention is extremely useful and has high industrial applicability because it provides highly practical effects such as improving the machining quality and machining speed of the workpiece. [Explanation of symbols]

[0102] 1. Laser processing device 5. Control Unit 11. First Laser Oscillator 12. Second laser oscillator 20 Laser processing heads 21. First collimating lens 22. Second collimating lens 24 1st adjustment mechanism 25 Second adjustment mechanism 26 Dichroic mirror (first optical component) 27 fθ lens (second optical element) 28 First detection unit 38 Second detection unit L1 First laser beam L2 Second laser beam Double job

Claims

1. A laser processing device that processes a workpiece by emitting laser light, A first laser oscillator that emits a first laser beam, A second laser oscillator that emits a second laser beam having a longer wavelength than the first laser beam, The system comprises a laser processing head that emits the first laser beam and the second laser beam, which are incident on the workpiece, from the first laser oscillator and the second laser oscillator, The aforementioned laser processing head is A first collimating lens that parallelizes the first laser beam, A second collimating lens that parallelizes the second laser beam, A first optical member that superimposes the first laser beam and the second laser beam that have passed through the first collimating lens and the second collimating lens, A second optical member that focuses the first laser beam and the second laser beam, which are superimposed by the first optical member, toward the workpiece, The system includes a first adjustment mechanism that adjusts the incident position of the first laser beam on the first optical member to relatively change the emission position of the first laser beam relative to the second laser beam, and further includes a detection unit that detects data indicating the melting state at the processing position of the workpiece. The system includes a control unit that controls the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit, The detection unit includes a first detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the first laser beam. By oscillating the first laser oscillator while stopping the second laser oscillator, the first laser beam is emitted from the laser processing head. The first detection unit detects the amount of scattered light from the first laser beam reflected by the workpiece. The laser processing apparatus is characterized in that the control unit causes the second laser oscillator to oscillate when the amount of scattered light detected by the first detection unit is lower than a predetermined threshold, and emits the second laser light from the laser processing head to the processing position of the workpiece.

2. A laser processing apparatus that processes a workpiece by emitting laser light, A first laser oscillator that emits a first laser beam, A second laser oscillator that emits a second laser beam with a longer wavelength than the first laser beam, The system comprises a laser processing head that emits the first laser beam and the second laser beam, which are incident on the workpiece, from the first laser oscillator and the second laser oscillator, The aforementioned laser processing head is A first collimating lens that parallelizes the first laser beam, A second collimating lens that parallelizes the second laser beam, A first optical member that superimposes the first laser beam and the second laser beam that have passed through the first collimating lens and the second collimating lens, A second optical member that focuses the first laser beam and the second laser beam, which are superimposed by the first optical member, toward the workpiece, The system includes a first adjustment mechanism that adjusts the incident position of the first laser beam on the first optical member to relatively change the emission position of the first laser beam relative to the second laser beam, and further includes a detection unit that detects data indicating the melting state at the processing position of the workpiece. The system includes a control unit that controls the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit, The detection unit includes a second detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the second laser beam. By oscillating the first laser oscillator and the second laser oscillator, the first laser beam and the second laser beam are emitted from the laser processing head. The second detection unit detects the amount of scattered light from the second laser beam reflected by the workpiece. The laser processing apparatus is characterized in that the control unit controls the operation of the second laser oscillator so as to increase the output of the second laser light stepwise or gradually when the amount of scattered light detected by the second detection unit is lower than a predetermined threshold.

3. A laser processing apparatus that processes a workpiece by emitting laser light, A first laser oscillator that emits a first laser beam, A second laser oscillator that emits a second laser beam with a longer wavelength than the first laser beam, The system comprises a laser processing head that emits the first laser beam and the second laser beam, which are incident on the workpiece, from the first laser oscillator and the second laser oscillator, The aforementioned laser processing head is A first collimating lens that parallelizes the first laser beam, A second collimating lens that parallelizes the second laser beam, A first optical member that superimposes the first laser beam and the second laser beam that have passed through the first collimating lens and the second collimating lens, A second optical member that focuses the first laser beam and the second laser beam, which are superimposed by the first optical member, toward the workpiece, The system includes a first adjustment mechanism that adjusts the incident position of the first laser beam on the first optical member to relatively change the emission position of the first laser beam relative to the second laser beam, and further includes a detection unit that detects data indicating the melting state at the processing position of the workpiece. The system includes a control unit that controls the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit, The detection unit includes a second detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the second laser beam. By oscillating the first laser oscillator and the second laser oscillator, the first laser beam and the second laser beam are emitted from the laser processing head. The second detection unit detects the amount of scattered light from the second laser beam reflected by the workpiece. The laser processing apparatus is characterized in that the control unit controls the operation of the laser processing head so that the first laser beam is emitted to the processing position of the workpiece when the amount of scattered light detected by the second detection unit is higher than a predetermined threshold.

4. A laser processing apparatus that processes a workpiece by emitting laser light, A first laser oscillator that emits a first laser beam, A second laser oscillator that emits a second laser beam with a longer wavelength than the first laser beam, The system comprises a laser processing head that emits the first laser beam and the second laser beam, which are incident on the workpiece, from the first laser oscillator and the second laser oscillator, The aforementioned laser processing head is A first collimating lens that parallelizes the first laser beam, A second collimating lens that parallelizes the second laser beam, A first optical member that superimposes the first laser beam and the second laser beam that have passed through the first collimating lens and the second collimating lens, A second optical member that focuses the first laser beam and the second laser beam, which are superimposed by the first optical member, toward the workpiece, The system includes a first adjustment mechanism that adjusts the incident position of the first laser beam on the first optical member to relatively change the emission position of the first laser beam relative to the second laser beam, and further includes a detection unit that detects data indicating the melting state at the processing position of the workpiece. The system includes a control unit that controls the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit, The detection unit includes a second detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the second laser beam. By oscillating the first laser oscillator and the second laser oscillator, the first laser beam and the second laser beam are emitted from the laser processing head. The second detection unit detects the amount of scattered light from the second laser beam reflected by the workpiece. The laser processing apparatus is characterized in that the control unit controls the operation of the first laser oscillator so as to increase the output of the first laser light stepwise or gradually when the amount of scattered light detected by the second detection unit is higher than a predetermined threshold.

5. A laser processing apparatus that processes a workpiece by emitting laser light, A first laser oscillator that emits a first laser beam, A second laser oscillator that emits a second laser beam with a longer wavelength than the first laser beam, The system comprises a laser processing head that emits the first laser beam and the second laser beam, which are incident on the workpiece, from the first laser oscillator and the second laser oscillator, The aforementioned laser processing head is A first collimating lens that parallelizes the first laser beam, A second collimating lens that parallelizes the second laser beam, A first optical member that superimposes the first laser beam and the second laser beam that have passed through the first collimating lens and the second collimating lens, A second optical member that focuses the first laser beam and the second laser beam, which are superimposed by the first optical member, toward the workpiece, The system includes a first adjustment mechanism that adjusts the incident position of the first laser beam on the first optical member to relatively change the emission position of the first laser beam relative to the second laser beam, and further includes a detection unit that detects data indicating the melting state at the processing position of the workpiece. The system includes a control unit that controls the operation of at least one of the laser processing head, the first laser oscillator, and the second laser oscillator based on the data detected by the detection unit, The detection unit includes a second detection unit that detects data indicating the melting state at the processing position of the workpiece corresponding to the second laser beam. By oscillating the first laser oscillator and the second laser oscillator, the first laser beam and the second laser beam are emitted from the laser processing head. The second detection unit detects the amount of scattered light from the second laser beam reflected by the workpiece. The laser processing apparatus is characterized in that the control unit controls the operation of the second laser oscillator so as to stop the output of the second laser light when the amount of scattered light detected by the second detection unit is higher than a predetermined upper limit.

6. In any one of claims 1 to 5, A laser processing apparatus characterized by comprising a second adjustment mechanism for adjusting the incident position of the second laser beam on the first optical member, thereby relatively changing the emission position of the second laser beam relative to the first laser beam.

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