Laser processing method and laser processing apparatus

Abstract

A method of laser processing a workpiece composed of at least one metal foil, including the steps of supplying excitation energy in a pulse form to a laser medium and generating laser light, the laser light including a pulsed light component and a continuous light component which is temporally successive to the pulsed light component, and irradiating the surface of the workpiece with the laser light, the method further including the step of limiting the duration of the continuous light component in such a manner that the ratio of the energy of the continuous light component to the energy of the pulsed light component becomes below a prescribed value.

Description

Technical Field

[0001] This invention relates to laser processing methods and laser processing apparatus. Background Technology

[0002] As a method for processing an object using a fiber laser device, the following method is disclosed: irradiating the object with a giant pulse to increase the temperature of the object and thus increase the laser absorption rate; after the giant pulse is generated, irradiating the object with a stably output laser to process the object (Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 6347676 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, in the method disclosed in Patent Document 1, the object is processed by irradiating it with a laser with a stable output. Therefore, when processing an object made of a thin metal foil, there is room for improvement, for example, when scum or discoloration sometimes occurs in the processed part.

[0008] The present invention was made in view of the above, and its object is to provide a laser processing method and a laser processing apparatus suitable for processing objects made of metal foil.

[0009] Solution for solving the problem

[0010] To achieve the above objectives, one aspect of the present invention is a laser processing method for processing an object composed of at least one metal foil. The laser processing method includes: supplying pulsed excitation energy to a laser medium to generate a laser beam; and irradiating the surface of the object with the laser beam. The laser beam includes a pulsed light component and a continuous light component that follows the pulsed light component in time. The laser processing method further includes a step of limiting the duration of the continuous light component by such that the ratio of the energy of the continuous light component to the energy of the pulsed light component is below a predetermined value.

[0011] Alternatively, the ratio may be 40 or less.

[0012] Alternatively, the ratio may be 5 or less.

[0013] Alternatively, the time width of the laser may be less than 12 μs.

[0014] Alternatively, the time width may be less than 2.3 μs.

[0015] Alternatively, the laser processing method may further include the step of supplying pulsed power to the excitation source and generating excitation light as the excitation energy.

[0016] Alternatively, the electrical pulse may be rectangular in shape and have a duration of less than 10 μs.

[0017] Alternatively, the electrical pulse can be rectangular in shape, and the time width can be set to be greater than or equal to the shortest on-time. The shortest on-time is the value by which the peak power of the pulsed light component decreases when the time width is narrower than the shortest on-time.

[0018] Alternatively, the repetition frequency of the electrical pulses may be 5 kHz or higher.

[0019] Alternatively, the repetition frequency of the electrical pulses may be above 50 kHz and below 300 kHz.

[0020] Alternatively, the laser processing method may further include a step of moving the laser irradiation position on the surface of the workpiece relative to the workpiece.

[0021] One aspect of the present invention is a laser processing apparatus for laser processing an object, wherein the laser processing apparatus comprises: a laser device that supplies pulsed excitation energy to a laser medium and generates a laser; an optical head that irradiates the laser onto the surface of the object being processed; and a control device that controls the laser device, wherein the control device controls the laser to include, in the initial stage of laser generation, a pulsed light component generated by relaxation oscillation and a continuous light component that follows the pulsed light component in time, and limits the duration of the continuous light component to a predetermined value such that the ratio of the energy of the continuous light component to the energy of the pulsed light component is below a predetermined value.

[0022] Invention Effects

[0023] According to the present invention, a laser processing method and a laser processing apparatus are available for processing objects made of metal foil. Attached Figure Description

[0024] Figure 1 This is a schematic structural diagram of the laser processing apparatus according to Embodiment 1.

[0025] Figure 2 yes Figure 1 The diagram shows a schematic structural representation of the laser device.

[0026] Figure 3 yes Figure 2 The diagram shows a schematic structural diagram of the drive unit.

[0027] Figure 4 This is a diagram showing the waveform of a laser pulse.

[0028] Figure 5 yes Figure 4 A magnified view of a portion of the time range.

[0029] Figure 6 This is a diagram illustrating the time width of the laser beam.

[0030] Figure 7 This is a graph illustrating an example of the relationship between repetition frequency and shortest on-time.

[0031] Figure 8 This is a schematic structural diagram of the laser processing apparatus according to Embodiment 2. Detailed Implementation

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to these embodiments. Furthermore, in each drawing, the same or corresponding elements are appropriately labeled with the same reference numerals, and repeated descriptions are omitted. Additionally, in some drawings, the XYZ orthogonal coordinate system is used to represent directions.

[0033] (Implementation Method 1)

[0034] Laser processing equipment

[0035] Figure 1 This is a schematic structural diagram of the laser processing apparatus according to Embodiment 1. The laser processing apparatus 100 includes a laser device 110, an optical head 120, an optical fiber 130 connecting the laser device 110 and the optical head 120, and a control device 140.

[0036] The laser processing device 100 is a device for laser cutting in laser processing such as welding, piercing, and cutting.

[0037] The object W to be processed by the laser processing device 100 is made of metallic material. The metallic material is, for example, copper-based materials such as copper or copper alloys, or aluminum-based materials such as aluminum or aluminum alloys.

[0038] Furthermore, the object being processed, W, consists of at least one sheet of metal foil. For example, the object being processed, W, may consist of a single sheet of metal foil or multiple sheets of metal foil stacked together. Here, the metal foil may be, for example, an aluminum-based rolled material with a thickness of 6 μm to 200 μm as specified in JIS H 4160, but the thickness is not limited to this; for example, it may be 500 μm or less, or 250 μm or less. The same applies when the metal foil is made of other metallic materials.

[0039] Alternatively, the workpiece W can also be an electrode of a battery such as a lithium-ion battery. In this case, an active material such as manganese dioxide or lithium can be coated onto the workpiece W. Alternatively, a material different from the active material can be coated onto the workpiece W, or a surface layer or film can be formed on the entire surface or partially.

[0040] Laser device 110, as an example, is configured to output a single-mode laser with a power of several kW. Laser device 110 will be described in detail later.

[0041] Fiber 130 guides the laser output from laser device 110 to optical head 120. When laser device 110 outputs single-mode laser, fiber 130 is configured to propagate the single-mode laser. In this case, the M-mode laser... 2 The beam quality is set to 1.2 or less. Furthermore, when the laser device 110 outputs multimode laser light, the optical fiber 130 is configured to propagate multimode laser light.

[0042] The optical head 120 is an optical device for irradiating the workpiece W with laser light input from the laser device 110. The optical head 120 has a collimating lens 121 and a condenser lens 122. It should be noted that the optical head 120 may also have optical components other than the collimating lens 121 and the condenser lens 122.

[0043] Collimating lens 121 collimates the input laser. Condensing lens 122 focuses the collimated laser and directs it as laser L (output light) onto the workpiece W.

[0044] With this structure, the optical head 120 irradiates the surface Wa of the object being processed with laser L in the negative direction of the Z-axis.

[0045] It should be noted that the irradiation position of the laser L on the surface of the workpiece W can be moved relative to the workpiece W. Such relative movement can be achieved by moving the optical head 120 relative to the workpiece W, moving the workpiece W, or moving both the optical head 120 and the workpiece W. For example, when the workpiece W is fixed and the optical head 120 is moved along the positive X-axis, the irradiation position of the laser L on the surface of the workpiece W is moved along... Figure 1 The scanning direction is SD scanning. To achieve such relative movement, the optical head 120 has a moving mechanism that can move in the XY direction, or the workpiece W is supported on a stage that allows the workpiece to move in the XY direction.

[0046] However, in the case of laser processing for perforation, the aforementioned relative movement is not necessary. Even in cutting and welding, such as spot welding or cutting of thin metal foils, there are cases where relative movement is not required.

[0047] The control device 140 controls the operation of the laser device 110 and the operation of the drive mechanism of the stage that supports the optical head 120 or the workpiece W. The control device 140 may, for example, be composed of a personal computer and its peripherals.

[0048] Figure 2 yes Figure 1 The diagram shows a schematic structural view of the laser device 110. The laser device 110 is configured as a CW laser device capable of outputting continuous wave (CW) laser light. Therefore, it is not necessary to have a Q-switching mechanism for outputting pulsed laser light.

[0049] The laser device 110 is a fiber laser and includes multiple semiconductor excitation sources 1, multiple optical fibers 2, an optical combiner 3, a fiber Bragg grating (FBG) 4, an amplification fiber 5, an FBG 7, an optical combiner 8, multiple optical fibers 9, multiple semiconductor excitation sources 6, an output fiber 11, and a drive unit 20. All components are appropriately connected via optical fibers. The output fiber 11 and... Figure 1 The optical fiber 130 shown is either an optically coupled component or a portion of the optical fiber 130 (input end). Each semiconductor excitation source 1 and 6 is an example of an excitation source and is configured as a laser diode module (LDM).

[0050] Each semiconductor excitation source 1 outputs excitation light to the amplification fiber 5. The amplification fiber 5 is an example of a laser medium, and the excitation light is an example of excitation energy. The excitation light has a wavelength capable of optically exciting the amplification fiber 5, for example, 915 nm. Multiple fibers 2 transmit the excitation light output from each semiconductor excitation source 1 to the optical combiner 3.

[0051] In this embodiment, the optical combiner 3 is composed of a TFB (Tapered Fiber Bundle). The optical combiner 3 combines the excitation optical waves input from each fiber 2 into the signal optical port of the fiber and outputs them to the amplification fiber 5.

[0052] The amplifying fiber 5 is a YDF (Ytterbium Doped Fiber) with ytterbium (Yb) ions added as an amplifying material to the core made of quartz glass. It is a double-clad fiber with an inner cladding made of quartz glass and an outer cladding made of resin or the like sequentially formed around the core. It should be noted that the NA of the core of the amplifying fiber 5 is, for example, 0.08, and the core is configured to transmit Yb ion emission in single mode, for example, light at a wavelength of 1070 nm. The absorption coefficient of the core of the amplifying fiber 5 is, for example, 200 dB / m at a wavelength of 915 nm. Furthermore, the power conversion efficiency from the excitation light input to the core to the laser oscillation light is, for example, 70%. However, the absorption coefficient and power conversion efficiency are not limited to these values.

[0053] The FBG4, serving as the back-end reflector, is connected between the optical fiber at the signal port of the optical combiner 3 and the amplification optical fiber 5. The FBG4 has a center wavelength of, for example, 1070 nm, and a reflectivity of approximately 100% in a band approximately 2 nm wide around the center wavelength, with most light at wavelength 915 nm transmitted. The FBG7, serving as the output-end reflector, is connected between the optical fiber at the signal port of the optical combiner 8 and the amplification optical fiber 5. The FBG7 has a center wavelength approximately the same as the FBG4, for example, 1070 nm, a reflectivity of 10% to 30% at the center wavelength, a full width at half maximum (FWHM) of approximately 1 nm in the reflected band, and most light at wavelength 915 nm transmitted.

[0054] FBG4 and 7 are respectively configured at both ends of the amplification fiber 5 to form an optical fiber resonator for light with a wavelength of 1070 nm.

[0055] Each semiconductor excitation source 6 outputs excitation light to the amplification fiber 5. The excitation light has a wavelength capable of optically exciting the amplification fiber 5, for example, 915 nm. Multiple optical fibers 9 transmit the excitation light output from each semiconductor excitation source 6 to the optical combiner 8.

[0056] Like optical combiner 3, optical combiner 8 is constructed using a TFB in this embodiment. Optical combiner 8 combines the excitation optical waves input from each optical fiber 9 into the optical fiber at the signal optical port and outputs them to the amplification optical fiber 5.

[0057] In the amplifying fiber 5, the Yb ions in the core are photoexcited by excitation light, emitting light in a frequency band including a wavelength of 1070 nm. The emission at a wavelength of 1070 nm is amplified by the amplifying fiber 5 and oscillated by the optical resonator composed of FBG4 and 7, thus generating laser light in the laser device 110.

[0058] The output fiber 11 is positioned on the opposite side of FBG7 and is connected to the optical fiber of the signal optical port of the optical combiner 8. The oscillated laser (laser oscillation light) is output from the output fiber 11.

[0059] The drive unit 20 supplies drive current to each semiconductor excitation light source 1 and 6 according to the instruction voltage signal input from the control device 140.

[0060] Figure 3 yes Figure 2 The diagram shows a schematic structural diagram of the drive unit. The drive unit 20 is mainly composed of analog circuits and includes a power supply device 21, an electric field-effect transistor (FET) 22, a shunt resistor 23, an operational amplifier 24, and a feedback circuit 25.

[0061] The power supply device 21 is a known DC power supply connected to each of the semiconductor excitation light sources 1 and 6 in a manner that supplies current. For example, each of the semiconductor excitation light sources 1 is connected in series, and each of the semiconductor excitation light sources 6 is connected in series separately from each of the semiconductor excitation light sources 1. Alternatively, all of the semiconductor excitation light sources 1 and each of the semiconductor excitation light sources 6 may be connected in series.

[0062] FET22 is connected downstream of each semiconductor excitation light source 1, 6 in the power line from power supply device 21 to ground. FET22 adjusts the amount of current supplied from power supply device 21 to each semiconductor excitation light source 1, 6 via the power line according to the applied gate voltage.

[0063] Shunt resistor 23 is connected downstream of FET 22 in the power supply line. Shunt resistor 23 has the function of extracting information about the amount of current flowing in the power supply line as a voltage value.

[0064] Operational amplifier 24 inputs the indicator voltage signal to the non-inverting input, inputs the voltage value of the shunt resistor 23 to the inverting input, and connects its output to the gate of FET 22.

[0065] The feedback circuit 25 is configured as an integrating circuit including a capacitor and forms a feedback path from the output of the operational amplifier 24 to the inverting input.

[0066] With the above structure, the drive unit 20 can perform constant current control to supply constant current to each semiconductor excitation light source 1, 6. The constant current is a current value corresponding to the level of the indicator voltage signal.

[0067] Laser processing methods

[0068] Next, we will take laser cutting as an example to illustrate a laser processing method using the laser processing device 100.

[0069] Initially, in the laser processing apparatus 100, the step of supplying pulsed excitation energy to the laser medium and generating laser light is performed. Specifically, firstly, the control device 140 performs the step of outputting a pulsed indicator voltage signal with a predetermined repetition period to the drive unit 20 of the laser device 110. As a result, the drive unit 20 performs the step of supplying pulsed driving power (driving current) to each of the semiconductor excitation light sources 1 and 6 and generating pulsed excitation light as excitation energy. Here, the pulse of driving power is, for example, rectangular in shape. Afterwards, in the laser device 110, each of the semiconductor excitation light sources 1 and 6 supplies pulsed excitation light to the amplification optical fiber 5, and generates pulsed laser light with a predetermined repetition period.

[0070] Next, the process involves irradiating the surface Wa of the workpiece W with laser light from the optical head 120, which has been input with laser light, and then moving the irradiation position of the laser light on the surface Wa of the workpiece W relative to the workpiece W. It should be noted that the step of moving the irradiation position of the laser light relative to the workpiece W can be performed by driving the stage supporting the workpiece W via the control device 140. This results in laser cutting of the workpiece W.

[0071] At this time, the laser L initially includes a pulsed light component generated by relaxation oscillation and a continuous light component that follows the pulsed light component in time. Furthermore, in the laser L, for example, when the energy ratio of the continuous light component to the pulsed light component is below a predetermined value, and the duration of the laser L is below a predetermined value, laser cutting that suppresses the generation of scum and discoloration can be performed. It should be noted that this energy ratio and duration can be controlled by the control device 140 to control the laser device 110.

[0072] Thus, by performing the steps of supplying pulsed excitation energy to the laser medium and generating laser light, the laser device 110 can generate pulsed light components without a Q-switching mechanism, for example, by using drive control of a general control circuit. Furthermore, the inventors have discovered that this pulsed light component, due to its sharp peaks generated by relaxation oscillations, can be applied to the processing of metal foils, which was previously difficult. The inventors have also discovered that if the power or energy of the continuous light component following the pulsed light component is too strong, the heat input to the metal foil is excessive, which is detrimental to the metal foil processing. Therefore, the inventors conceived of the following technical idea: by controlling the duration of the continuous light component to limit the ratio of the energy of the continuous light component to the energy of the pulsed light component to a predetermined value, the heat input can be adjusted to achieve appropriate metal foil processing. Furthermore, the inventors have also discovered that the desired energy ratio adjustment can be easily achieved by adjusting the pulse width of the pulsed power supplied to each semiconductor excitation light source 1, 6.

[0073] The energy ratio is 40 or less, and the laser wavelength L is 12 μs or less. Furthermore, the duration of the continuous light component is defined as described later. Figure 5 , 6 The time from time t3 to time t9 is used, but it is not particularly limited as long as it is a definition representing the length of time during which a continuous light component has power.

[0074] The following provides a more detailed explanation of the waveforms and experimental examples using the laser's time axis. Figure 4 This is a diagram showing the waveform of one pulse of laser L. Figure 5 yes Figure 4 A magnified view of a portion of the time range. Figure 4 , 5 In the diagram, the horizontal axis represents time [μs], and the vertical axis represents power [W]. The time on the horizontal axis is defined as the time before the generation of a pulse of laser L, set to 0 μs. For example... Figure 4 As shown, laser L consists of a pulsed light component PC and a continuous light component CC in one pulse.

[0075] In the laser device 110, pulsed excitation light is supplied from each of the semiconductor excitation sources 1 and 6 to the amplification fiber 5, thereby generating a pulsed light component PC caused by relaxation oscillation based on the upright shape of the excitation light. The pulsed light component PC has a sharp peak shape with high power and short pulse width. Subsequently, a continuous light component CC is generated sequentially after the pulsed light component PC, but the power of the continuous light component CC decreases earlier due to the decline of the excitation light. It should be noted that line L1 represents the time t1 before the generation of the pulsed light component PC, and line L2 represents the position of the time t2 after the decay of the continuous light component CC. At any given time, the power of the light is 0W.

[0076] Line L3 represents the position of t3, the moment when the power of the pulsed light component PC in laser L first reaches its minimum after reaching its peak. In this specification, the position of this minimum is defined as the boundary between the pulsed light component PC and the continuous light component CC. It should be noted that... Figure 4 In the process, after time t3, a vibrational component with a power smaller than that of the pulsed light component PC is also generated, but in this specification, this component is also included in the continuous light component CC. Therefore, the energy of the pulsed light component PC is obtained by integrating the power of the pulsed light component PC over time, for example, from time t1 to time t3. The unit of energy is, for example, joules. Similarly, the energy of the continuous light component CC is obtained by integrating the power of the continuous light component CC over time from time t3 to time t2. It should be noted that time t1 is not limited to this value as long as the power of the pulsed light component PC is 0W, and time t2 is not limited to this value as long as the power of the continuous light component CC is 0W.

[0077] In addition, in this embodiment, the time width of the laser L is 12 μs or less. Figure 6This is an illustration of the laser's time width. Line L4 represents the peak power level of the pulsed light component PC, and line L5 represents 50% of the peak power level. Additionally, line L6 represents the maximum power level of the continuous light component CC, and line L7 represents 50% of the maximum power level. In this specification, the laser's time width TW is defined using the time width from the moment t8 (represented by line L8) when the pulsed light component PC reaches 50% of its peak value to the moment t9 (represented by line L9) when the continuous light component CC decreases and reaches 50% of its maximum value.

[0078] In this embodiment, the energy ratio of the continuous light component CC to the pulsed light component PC is set to, for example, 40 or less, and the laser pulse width TW is set to, for example, 12 μs or less. Therefore, a thin workpiece W made of metal foil can be processed using the pulsed light component PC, which has higher power and a shorter pulse width, and excessive heat input to the workpiece W by the continuous light component CC is suppressed by appropriately reducing its power. As a result, defects such as scum and discoloration at the processed portion can be suppressed.

[0079] Furthermore, when the energy ratio is less than 5 or the time width (TW) is less than 2.3 μs, the heat input generated by the continuous light component (CC) is further suppressed, thus further suppressing the occurrence of adverse conditions caused by the heat input.

[0080] The values ​​of energy ratio and time width TW can also be appropriately set according to the characteristics of the processed object W, such as the material, thickness, and number of sheets of the metal foil.

[0081] It should be noted that the waveform and power of laser L vary depending on the waveform of the excitation light pulses output by each semiconductor excitation light source 1 and 6. The waveform of the excitation light pulses varies depending on the waveform of the drive power pulses from the drive unit 20. Furthermore, the waveform of the drive power pulses can be controlled using the waveform of the pulses of the indicator voltage signal from the control device 140. Therefore, the waveform and power of laser L can be controlled by changing the waveform of the pulses of the indicator voltage signal from the control device 140.

[0082] Furthermore, the repetition frequency of the driving power pulse is not particularly limited, but is, for example, 5 kHz or higher. If the repetition frequency is 5 kHz or higher, it is easy to obtain the preferred waveform for the laser L, which has an energy ratio of 40 or less and a time width TW of 12 μs or less. The on-time of the driving power pulse is the time width of the driving power pulse.

[0083] Furthermore, while a relatively narrow pulse width of the driving power is suitable for reducing the energy of the continuous light component (CC), according to the present invention, the peak power of the pulsed light component (PC) decreases when the pulse width is too narrow. Therefore, in order to efficiently utilize the energy of the pulsed light component (PC) in laser processing, a narrow pulse width that does not reduce the peak power of the pulsed light component (PC) is preferable. Thus, in this specification, a minimum on-time is defined as one of the indicators of the pulse width of the driving power. The minimum on-time is the value at which the peak power of the pulsed light component decreases when the pulse width of the driving power is narrower than this minimum on-time. In this case, if the pulse width of the power is set to be greater than or equal to the minimum on-time, the energy of the pulsed light component (PC) can be efficiently utilized in laser processing.

[0084] Figure 7 This is a graph showing the relationship between the repetition frequency and the shortest on-time in a laser device with the same structure as the laser device 110 in Embodiment 1. The horizontal axis represents the repetition frequency of the driving power pulses, and the vertical axis represents the shortest on-time. Furthermore, the values ​​from "104" to "1002" in the example represent the average power [W] in a steady state under the conditions of each indicated value set for the laser device 110. Here, the indicated value is the voltage value of the indicated voltage signal. It should be noted that the laser device 110 is configured with a rated laser output of 1000W.

[0085] like Figure 7 As shown, the shortest on-time increases as the repetition frequency decreases. Furthermore, the shortest on-time increases as the average power decreases. To ensure the time width TW of the laser L waveform is set to 12 μs or less, the on-time of the driving power pulse is preferably set to 10 μs or less. In this case, if the repetition frequency is set to 5 kHz or higher, the on-time can be set to the shortest possible duration for various average power values.

[0086] It should be noted that although the laser device 110 is configured as a CW laser device, it can generate a pulsed light component PC with a sharp peak using relaxation oscillation. Therefore, it can be configured as a simpler and lower-cost device compared to a pulsed laser device with a Q-switching mechanism.

[0087] (Processing Experiment)

[0088] A laser processing apparatus with the same structure as the laser processing apparatus 100 in Embodiment 1 was fabricated, and a cutting experiment was conducted on a workpiece made of metal foil. The workpiece was a copper foil with a thickness of 8 μm. The driving power was set such that the average power in a stable state under various indicated values ​​was 1000 W. The repetition frequency of the driving power pulses was set to various values ​​from less than 5 kHz to 300 kHz. Furthermore, the on-time of the driving power pulses was set to various values ​​from 0.5 μs to 100 μs.

[0089] Table 1 shows the processing results. Regarding processing quality, visual inspection using a microscope was conducted from the perspective of scum and discoloration (such as the formation of oxide layers), and grades were assigned according to prescribed evaluation criteria. Here, quality with unacceptably large scum size was rated as "poor," quality with acceptable scum size and a large but tolerable oxide layer size was rated as "good," quality with a small scum size and a moderately large oxide layer size but higher quality was rated as "excellent," and quality with both scum and oxide layer small size and the highest quality was rated as "best." Additionally, "-" indicates conditions where no experiment was conducted. As shown in Table 1, "good" or "excellent" results were obtained when the energy ratio R was 40 or less and the laser time width TW was 12 μs or less, and "excellent" or "best" results were obtained when the energy ratio R was 5 or less and the laser time width TW was 2.3 μs or less. In particular, when the repetition frequency is 5 kHz or higher and 50 kHz, a "good" result is obtained when the laser time width (TW) exceeds 2.3 μs and is less than 12 μs, and a "superior" result is obtained when it exceeds 0.1 μs and is less than 2.3 μs. Furthermore, when the repetition frequency is 50 kHz or higher and less than 300 kHz, a "superior" result is obtained when the laser time width (TW) exceeds 2.3 μs and is less than 12 μs, and a "optimal" result is obtained when it exceeds 0.1 μs and is less than 2.3 μs.

[0090] [Table 1]

[0091] (Table 1)

[0092]

[0093] (Implementation Method 2)

[0094] Figure 8This is a schematic structural diagram of the laser processing apparatus according to Embodiment 2. In this embodiment, the optical head 120 has an electrical scanner 126 between the collimating lens 121 and the condenser lens 122. The electrical scanner 126 has two reflectors 126a. By changing the orientation of these two reflectors 126a, the irradiation direction and position of the laser L are changed. That is, the laser processing apparatus 100A can move the irradiation position of the laser L without moving the optical head 120 and scan the laser L. The control device 140 can control the operation of the motors 126b corresponding to each reflector 126a in a manner that changes the angle (or orientation) of the reflectors 126a. Through this embodiment, the same function and effect as in Embodiment 1 can also be obtained.

[0095] It should be noted that in the above embodiment, the amplifying optical fiber 5 is YDF, but it can also be an amplifying optical fiber with other rare earth elements such as erbium and neodymium added as the amplification medium. In this case, the wavelength of the excitation light and the wavelength of the generated laser are set to wavelengths corresponding to the type of amplification medium.

[0096] In addition, in the above embodiment, the laser device 110 is a fiber laser, but it may also be a laser device that uses other types of lasers such as semiconductor lasers and solid-state lasers.

[0097] Furthermore, in the above embodiment, the pulse of driving power is rectangular in shape, but the ratio of the energy of the continuous light component to the energy of the pulsed light component is 40 or less. As long as a laser with a laser duration of 12 μs or less can be generated, the shape is not limited to rectangular. The shape of the excitation light pulse is also not limited.

[0098] Furthermore, the present invention is not limited to the embodiments described above. Embodiments constructed by appropriately combining the aforementioned constituent elements are also included in the present invention. In addition, further effects and modifications can be readily derived by those skilled in the art. Therefore, the broader scope of the present invention is not limited to the embodiments described above, and various modifications are possible.

[0099] Industrial applicability

[0100] As described above, the present invention is preferably applied to laser processing methods and laser processing apparatus.

[0101] Explanation of reference numerals in the attached figures:

[0102] 1, 6: Semiconductor excitation source

[0103] 2, 9, 130: Fiber optic

[0104] 3, 8: Optical wave combiner

[0105] 5: Fiber optic cable for amplification

[0106] 11: Output optical fiber

[0107] 20: Drive Unit

[0108] 21: Power supply device

[0109] 22: FET

[0110] 23: Shunt resistor

[0111] 24: Operational amplifier

[0112] 25: Feedback Circuit

[0113] 100, 100A: Laser processing equipment

[0114] 110: Laser device

[0115] 120: Optical head

[0116] 121: Collimating Lens

[0117] 122: Condensing Lens

[0118] 126: Electronic Scanner

[0119] 126a: Reflector

[0120] 126b: Motor

[0121] 140: Control device

[0122] CC: Continuous light component

[0123] L: Laser

[0124] PC: Pulsed light component

[0125] SD: Scan direction

[0126] TW: Time Width

[0127] W: Processing object

[0128] Wa: surface.

Claims

1. A laser processing method for processing an object consisting of at least one metal foil, wherein, The laser processing method includes: The step of supplying pulsed power to a semiconductor excitation light source to generate pulsed excitation light; The steps of supplying the excitation light to the amplification fiber of the fiber laser and generating laser light by optical excitation; and The step of irradiating the surface of the object being processed with the laser. The laser includes a pulsed light component generated in the initial stage of laser generation due to relaxation oscillations in the fiber laser, and a continuous light component that follows the pulsed light component in time. The laser processing method further includes the step of limiting the duration of the continuous light component in such a way that the ratio of the energy of the continuous light component to the energy of the pulsed light component is below a predetermined value.

2. The laser processing method according to claim 1, wherein, The ratio of the energy of the continuous light component to the energy of the pulsed light component is less than 40.

3. The laser processing method according to claim 2, wherein, The ratio of the energy of the continuous light component to the energy of the pulsed light component is 5 or less.

4. The laser processing method according to any one of claims 1 to 3, wherein, The time width of the laser is less than 12 μs.

5. The laser processing method according to claim 4, wherein, The time width is less than 2.3 μs.

6. The laser processing method according to any one of claims 1 to 3, wherein, The electrical pulses are rectangular in shape and have a duration of less than 10 μs.

7. The laser processing method according to any one of claims 1 to 3, wherein, The electrical pulses are rectangular in shape, and their duration is set to be greater than or equal to the minimum on-time. The shortest on-time is the reduction in peak power of the pulsed light component when the time width is narrower than the shortest on-time.

8. The laser processing method according to any one of claims 1 to 3, wherein, The repetition frequency of the electrical pulses is above 5 kHz.

9. The laser processing method according to claim 8, wherein, The repetition frequency of the electrical pulses is above 50 kHz and less than 300 kHz.

10. The laser processing method according to any one of claims 1 to 3, wherein, The laser processing method further includes the step of moving the laser irradiation position on the surface of the workpiece relative to the workpiece.

11. A laser processing apparatus for laser processing an object consisting of at least one metal foil, wherein, The laser processing apparatus includes: A laser device, which is a fiber laser, includes a semiconductor excitation source and an amplification fiber. Pulsed power is supplied to the semiconductor excitation source to generate pulsed excitation light. Pulsed excitation light is supplied from the semiconductor excitation source to the amplification fiber and laser is generated through optical excitation. An optical head that irradiates the surface of the object being processed with the laser; and Control device, which controls the laser device The control device performs the following control: the laser includes a pulsed light component generated in the early stage of laser generation due to relaxation oscillation in the fiber laser and a continuous light component that follows the pulsed light component in time, and the duration of the continuous light component is limited such that the ratio of the energy of the continuous light component to the energy of the pulsed light component is below a predetermined value.

Images