Laser processing system

Abstract

A first detector 51 detects the light intensity of laser light L emitted from a laser processing machine 10. A second detector 52 detects the light intensity of emitted light 60 emitted from a workpiece W during laser processing. A first determination apparatus 30 determines, on the basis of the light intensities detected by the first detector 51 and the second detector 52, whether or not there is a failure in either or both of the states of the laser processing machine 10 and the workpiece W.

Description

Laser Processing System

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

[0002] Patent Document 1 discloses a method for determining the state of laser processing, which detects defects in processing of a workpiece by detecting reflected light, plasma light, or thermal radiation light emitted from the workpiece (workpiece) during welding and monitoring the welding state of the workpiece.

[0003] International Publication No. 2021 / 182582

[0004] However, even if a processing defect in a workpiece is detected, it is not possible to distinguish and determine whether the main cause is on the workpiece side, such as due to dirt on the workpiece, or on the laser processing machine side, such as due to deterioration of optical components.

[0005] Specifically, when a problem occurs in processing a workpiece, the worker first checks the condition of the workpiece (scratches, dents, dirt, etc.) and then checks the condition of the laser processing machine (deterioration of the optical components of the processing head, etc.).

[0006] In this way, in order to identify the cause of a processing defect in a workpiece, it is necessary to check the condition of the workpiece and the condition of the laser processing machine in stages, which increases the number of work steps and takes time.

[0007] The present invention has been made in view of the above points, and its object is to make it possible to easily identify the cause of a problem when the problem occurs during laser processing.

[0008] The first aspect comprises a laser processing machine that emits laser light onto a workpiece, a first detector that detects the light intensity of the laser light emitted from the laser processing machine, a second detector that detects the light intensity of the light emitted from the workpiece during laser processing, and a first judgment device that judges whether there is a problem with the laser processing machine or the condition of the workpiece based on the light intensities detected by the first detector and the second detector, respectively.

[0009] In the first aspect, whether there is a problem with the laser processing machine or the state of the workpiece is determined based on the light intensities detected by the first detector and the second detector, respectively. This makes it possible to easily identify the cause of a problem when a problem such as poor penetration of the workpiece occurs during laser processing.

[0010] Specifically, if the light intensity of the laser light detected by the first detector is lower than the light intensity of the laser light during normal operation, it can be determined that, for example, the optical components of the laser processing machine have deteriorated and there is a malfunction in the laser processing machine.

[0011] On the other hand, if the light intensity of the emitted light detected by the second detector fluctuates significantly compared to the light intensity of the emitted light during normal operation, it can be determined that the workpiece has a defect, for example, scratches, dents, dirt, etc.

[0012] In a second aspect, in the laser processing system of the first aspect, the laser processing machine has a laser oscillator that oscillates the laser light, and a processing head that emits the laser light oscillated by the laser oscillator toward the workpiece, and is equipped with a third detector that detects the light intensity of the laser light oscillated by the laser oscillator, and a fourth detector that detects the light intensity of scattered light on the emission side of the processing head, and is equipped with a second judgment device that judges whether there is a malfunction in the laser oscillator or the processing head based on the light intensities detected by the first detector, the third detector, and the fourth detector, respectively.

[0013] In the second aspect, it is determined whether there is a problem with the laser oscillator or the processing head based on the light intensities detected by the first detector, the third detector, and the fourth detector, respectively.

[0014] Specifically, if the light intensity of the laser light detected by the third detector is lower than the light intensity of the laser light during normal operation, it can be determined that, for example, the optical components of the laser oscillator have deteriorated and there is a malfunction in the laser oscillator.

[0015] Furthermore, if the light intensity of the scattered light detected by the fourth detector is greater than the light intensity of the laser light during normal operation, it can be determined that there is a problem with the processing head, for example, due to the focusing lens of the processing head being dirty.

[0016] A third aspect is a laser processing system according to the second aspect, wherein the laser processing machine has a transmission fiber that transmits the laser light oscillated by the laser oscillator to the processing head, and is equipped with a fifth detector that detects the light intensity of scattered light on the incident side of the transmission fiber and a sixth detector that detects the light intensity of scattered light on the exit side of the transmission fiber, and the second determination device determines whether or not there is a defect in the transmission fiber based on the light intensities detected by the fifth detector and the sixth detector, respectively.

[0017] In the third aspect, it is determined whether or not there is a defect in the transmission fiber based on the light intensities detected by the fifth detector and the sixth detector.

[0018] Specifically, if the light intensity of the scattered light detected by the fifth or sixth detector is greater than the light intensity of the scattered light during normal operation, it can be determined that the input or output end of the transmission fiber has deteriorated and there is a problem with the transmission fiber.

[0019] According to aspects of the present disclosure, when a malfunction occurs during laser processing, the cause of the malfunction can be easily identified.

[0020] FIG. 1 is a block diagram showing the configuration of a laser processing system according to this embodiment. FIG. 2 is a side cross-sectional view showing the schematic configuration of a processing head. FIG. 3 is a side cross-sectional view showing the schematic configuration of a spectroscopic device. FIG. 4 is a diagram showing the waveform of reflected light measured by the spectroscopic device. FIG. 5 is a diagram showing the waveform of plasma light measured by the spectroscopic device. FIG. 6 is a diagram showing the waveform of thermal radiation light measured by the spectroscopic device. FIG. 7 is a flowchart showing the process of determining an abnormality location. FIG. 8 is a flowchart showing the process of identifying a defective location. FIG. 9 is a diagram showing the relationship between factors of various defects in the laser processing system and the light intensity detected by each detector. FIG. 10 is a side cross-sectional view showing the schematic configuration of a processing head according to a modified example of this embodiment.

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses.

[0022] As shown in FIG. 1, the laser processing system 1 includes a laser processing machine 10, a first determination device 30 serving as a workpiece determination device, and a second determination device 40 serving as a monitoring device.

[0023] The laser processing machine 10 has a laser oscillator 11 , a transmission fiber 12 , an oscillator control unit 13 , a processing head control unit 14 , and a processing head 20 .

[0024] The laser oscillator 11 oscillates laser light L. For example, a solid-state laser light source, a gas laser light source, or a fiber laser light source can be used as the laser oscillator 11. The laser oscillator 11 may also be a semiconductor laser light source that directly uses light emitted from a semiconductor laser, or a semiconductor laser array that includes a plurality of laser light emitters.

[0025] The laser oscillator 11 is connected to an input end of a transmission fiber 12. The processing head 20 is connected to an output end of the transmission fiber 12. The laser light L emitted from the laser oscillator 11 is transmitted to the processing head 20 via the transmission fiber 12.

[0026] As will be described in more detail later, the laser processing machine 10 has a first detector 51 (see Figure 2), a second detector 52 (see Figure 3), a third detector 53, a fourth detector 54 (see Figure 2), a fifth detector 55, and a sixth detector 56.

[0027] The laser oscillator 11 has a third detector 53. The third detector 53 is arranged on the output side inside the laser oscillator 11. The third detector 53 is configured with, for example, a photodiode. The third detector 53 is an oscillator output PD sensor that detects the light intensity of the laser light L oscillated by the laser oscillator 11. The oscillator output PD value, which is a value indicating the light intensity detected by the third detector 53, is transmitted to the oscillator control unit 13.

[0028] A fifth detector 55 is disposed at the incident end of the transmission fiber 12. The fifth detector 55 is configured by, for example, a photodiode. The fifth detector 55 is a fiber incident scattered light PD sensor that detects the light intensity of scattered light generated on the incident side of the transmission fiber 12. A fiber incident scattered light PD value, which is a value indicating the light intensity detected by the fifth detector 55, is transmitted to the oscillator control unit 13.

[0029] A sixth detector 56 is disposed at the exit end of the transmission fiber 12. The sixth detector 56 is configured, for example, by a photodiode. The sixth detector 56 is a fiber exit scattered light PD sensor that detects the light intensity of scattered light generated at the exit side of the transmission fiber 12. The fiber exit scattered light PD value, which is a value indicating the light intensity detected by the sixth detector 56, is transmitted to the machining head control unit 14.

[0030] As shown in Figure 2, the processing head 20 has a collimating lens 21, a dichroic mirror 22, a first condensing lens 23, a reflecting mirror 24, a second condensing lens 25, a first detector 51, and a fourth detector 54.

[0031] The collimating lens 21 collimates the laser light L transmitted through the transmission fiber 12 .

[0032] The dichroic mirror 22 reflects most of the laser light L collimated by the collimator lens 21 toward the first condenser lens 23, while transmitting a portion of the laser light L.

[0033] The first detector 51 is configured by, for example, a photodiode. The first detector 51 is a head output PD sensor that detects the light intensity of the laser light L emitted from the laser processing machine 10.

[0034] The first detector 51 is disposed at a position where it can detect the laser light L transmitted through the dichroic mirror 22. The head output PD value, which is a value indicating the light intensity detected by the first detector 51, is transmitted to the machining head control unit 14 and a machining defect determiner 35 (described later) of the first determination device 30.

[0035] It is preferable that the first detector 51 is configured not to reflect the laser light L. This is to prevent the laser light L reflected by the first detector 51 from unintentionally entering the spectrometer 31 and affecting the accuracy of workpiece determination.

[0036] The first condenser lens 23 condenses the laser light L reflected by the dichroic mirror 22. The laser light L condensed by the first condenser lens 23 is emitted toward the workpiece W.

[0037] The fourth detector 54 is configured by, for example, a photodiode. The fourth detector 54 is a head scattered light PD sensor that detects the light intensity of scattered light on the exit side of the processing head 20.

[0038] The fourth detector 54 is disposed on the output side of the first condenser lens 23. Specifically, the fourth detector 54 is disposed near the first condenser lens 23 and along the inner wall surface of the housing of the machining head 20. This prevents the laser light L from being directly irradiated onto the fourth detector 54. The head scattered light PD value, which is a value indicating the light intensity detected by the fourth detector 54, is transmitted to the machining head control unit 14.

[0039] 2, only one fourth detector 54 is disposed in the machining head 20, but the present invention is not limited to this. For example, three or more fourth detectors 54 may be disposed around the periphery of the first condenser lens 23. In this way, it is possible to estimate the location of deterioration in the first condenser lens 23 based on the difference in light intensity of the scattered light detected by each of the multiple fourth detectors 54.

[0040] 1 , the machining head control unit 14 controls the operation of the machining head 20. The fiber-emitted scattered light PD value, the head output PD value, and the head scattered light PD value are input to the machining head control unit 14. The machining head control unit 14 transmits the fiber-emitted scattered light PD value, the head output PD value, and the head scattered light PD value to the oscillator control unit 13.

[0041] The oscillator control unit 13 controls the operation of the laser oscillator 11. The oscillator output PD value and the fiber-entered scattered light PD value are input to the oscillator control unit 13 from the laser oscillator 11. The oscillator control unit 13 transmits the oscillator output PD value, the fiber-entered scattered light PD value, the fiber-emitted scattered light PD value, the head output PD value, and the head scattered light PD value to a malfunction determiner 41 (described later) of the second determination device 40.

[0042] The oscillator control unit 13 and the machining head control unit 14 are configured by a microcomputer, a computer that combines hardware and software, or the like, and are realized, for example, by combining an AD board and a computer.

[0043] 2, when laser light L is emitted from the machining head 20 toward the workpiece W, emitted light 60 is emitted from the workpiece W. The emitted light 60 passes through the dichroic mirror 22. The emitted light 60 that has passed through the dichroic mirror 22 is reflected by the reflecting mirror 24 and then focused by the second focusing lens 25. The emitted light 60 focused by the second focusing lens 25 enters the spectrometer 31 of the first determination device 30 via the transmission fiber 12a.

[0044] 1, the first determination device 30 includes a spectroscopic device 31 and a processing defect determiner 35. The spectroscopic device 31 separates the emitted light 60 into predetermined wavelengths. Specifically, the emitted light 60 includes reflected light 61, plasma light 62, and thermal radiation light 63 (see FIG. 3).

[0045] The reflected light 61 tends to be easily affected by the penetration of the workpiece W and conforms to the wavelength of the laser light L. The wavelength of the reflected light 61 is, for example, 445±20 nm, 975±30 nm, or 1070 nm.

[0046] The plasma light 62 tends to react easily to the bead width, dirt on the surface of the workpiece W, spatter, etc., and the wavelength emitted varies depending on the material of the workpiece W. The plasma light 62 is emitted when plasma is generated in the workpiece W. The wavelength of the plasma light 62 is, for example, 400 to 700 nm.

[0047] The thermal radiation light 63 tends to be sensitive to the laser power output from the laser oscillator 11, and the wavelength emitted varies depending on the melting temperature of the workpiece W. The wavelength of the thermal radiation light 63 is distributed widely, for example, from 1000 to 1500 nm.

[0048] 3, the spectroscopic device 31 has a plurality of second detectors 52. The second detectors 52 are configured, for example, with photodiodes. The second detectors 52 detect the light intensity of emitted light 60 emitted from the workpiece W. The second detectors 52 include a thermal radiation light detector 52a, a reflected light detector 52b, and a plasma light detector 52c.

[0049] The thermal radiation light detector 52a is a thermal radiation light PD sensor that detects the light intensity of the thermal radiation light 63. The reflected light detector 52b is a reflected light PD sensor that detects the light intensity of the reflected light 61. The plasma light detector 52c is a plasma light PD sensor that detects the light intensity of the plasma light 62.

[0050] The spectroscopic device 31 has a collimating lens 32, a first mirror 33a, a second mirror 33b, a third mirror 33c, a first condenser lens 34a, a second condenser lens 34b, and a third condenser lens 34c.

[0051] The collimating lens 32 collimates the emitted light 60 transmitted to the spectrometer 31 via the transmission fiber 12a. The emitted light 60 collimated by the collimating lens 32 is incident on a first mirror 33a.

[0052] The first mirror 33a transmits the thermal radiation light 63 while reflecting the reflected light 61 and plasma light 62. The first condenser lens 34a condenses the thermal radiation light 63 that has transmitted through the first mirror 33a. The thermal radiation light 63 condensed by the first condenser lens 34a is incident on the thermal radiation light detector 52a. The thermal radiation light detector 52a detects a thermal radiation light PD value, which is a value indicating the light intensity of the thermal radiation light 63. The thermal radiation light PD value is sent to the processing defect determiner 35.

[0053] The second mirror 33b transmits the plasma light 62 and reflects the reflected light 61. The reflected light 61 reflected by the second mirror 33b is focused by the second focusing lens 34b. The reflected light 61 focused by the second focusing lens 34b is incident on the reflected light detector 52b. The reflected light detector 52b detects a reflected light PD value, which is a value indicating the light intensity of the reflected light 61. The reflected light PD value is sent to the processing defect determiner 35.

[0054] Third mirror 33c reflects plasma light 62. Plasma light 62 reflected by third mirror 33c is focused by third condenser lens 34c. Plasma light 62 focused by third condenser lens 34c is incident on plasma light detector 52c. Plasma light detector 52c detects the plasma light PD value, which is a value indicating the light intensity of plasma light 62. The plasma light PD value is sent to processing defect determiner 35.

[0055] In this embodiment, the first mirror 33 a, the second mirror 33 b, and the third mirror 33 c are used to separate the emitted light 60 into three wavelengths: reflected light 61, plasma light 62, and thermal radiation light 63, but the present invention is not limited to this configuration.

[0056] For example, instead of the first mirror 33a, the second mirror 33b, and the third mirror 33c, a prism or a grating plate may be used to separate the emitted light 60 into three wavelengths: reflected light 61, plasma light 62, and thermal radiation light 63.

[0057] The order in which the first mirror 33a, the second mirror 33b, and the third mirror 33c are arranged is not limited to this form, and can be changed to any order, for example, by appropriately adjusting the settings of the optical films of the mirrors.

[0058] The machining defect determiner 35 determines machining defects of the workpiece W. Specifically, the reflected light PD value, the plasma light PD value, and the thermal radiation light PD value are input to the machining defect determiner 35 from the spectroscopic device 31 side.

[0059] Here, in order to ensure traceability, the laser processing machine 10 assigns a workpiece ID to the workpiece W for each processing. The head output PD value and the workpiece ID are input to the processing defect determiner 35 from the laser processing machine 10 side.

[0060] In this way, the head output PD value, which is an output closer to the machining point of the workpiece W than the laser oscillator 11, is used to determine machining defects, rather than the oscillator output PD value detected within the laser oscillator 11. Furthermore, the machining head 20 is relatively easy to position close to the first determination device 30. Therefore, noise can be reduced when the head output PD value is input to the first determination device 30.

[0061] The processing defect determiner 35 determines whether there is a defect in the state of the laser processing machine 10 or the workpiece W based on the reflected light PD value, the plasma light PD value, the thermal radiation light PD value, and the head output PD value.

[0062] Specifically, as shown in Figure 4, if the signal strength indicating the light intensity of the laser light L remains stable at a predetermined value (8 V in Figure 4), while the signal strength of the reflected light 61 remains within a predetermined allowable range (4 to 6 V in Figure 4), the processing quality of the workpiece W is determined to be normal.

[0063] In contrast, if the signal strength of the laser light L remains stable at a predetermined value (8 V in Figure 4) while the signal strength of the reflected light 61 remains above the upper limit of a predetermined tolerance range (4 to 6 V in Figure 4), it is determined that a processing defect has occurred in the workpiece W.

[0064] Specifically, compared to normal laser processing, there is a tendency for less energy to be absorbed by the workpiece W, and the reflected light 61 increases accordingly. In other words, by using the rate of increase from the value of the reflected light PD during normal laser processing as an index, it is possible to detect processing defects in the workpiece W. The type of problem in this case is insufficient penetration of the workpiece W.

[0065] In the example of a processing defect shown in Figure 4, the signal strength of the laser light L is stable, and the reflected light from the workpiece W exceeds the allowable range, so it can be determined that there is a defect in the condition of the workpiece W.

[0066] Furthermore, as shown in Figure 5, if the signal strength indicating the light intensity of the laser light L remains stable at a predetermined value (8 V in Figure 5), while the signal strength of the plasma light remains within a predetermined allowable range (4 to 6 V in Figure 5), the processing quality of the workpiece W is determined to be normal.

[0067] In contrast, if the signal strength of the laser light L remains stable at a predetermined value (8 V in Figure 5), while the signal strength of the plasma light alternately exceeds the upper limit of a predetermined tolerance range (4 to 6 V in Figure 5) and falls below the lower limit, it is determined that a processing defect has occurred in the workpiece W.

[0068] Specifically, when contamination occurs on the welded surface of the workpiece W due to spatter, which are tiny particles of molten metal that scatter during laser processing, or ripples, which are cracks that occur along the wave pattern of the weld bead, the amount of plasma light 62 generated at the welded portion of the workpiece W tends to increase or decrease. In other words, by using the increase in the amplitude of the waveform of the plasma light 62 compared to normal laser processing as an indicator, it is possible to detect processing defects in the workpiece W. The types of trouble in this case are the occurrence of spatter or ripples.

[0069] In the example of a processing defect shown in Figure 5, the signal strength of the laser light L is stable, and the plasma light from the workpiece W exceeds the allowable range, so it can be determined that there is a defect in the condition of the workpiece W.

[0070] Furthermore, as shown in Figure 6, if the signal strength indicating the light intensity of the laser light L remains stable at a predetermined value (8 V in Figure 6), while the signal strength of the thermal radiation light 63 remains within a predetermined allowable range (4 to 6 V in Figure 6), the processing quality of the workpiece W is determined to be normal.

[0071] In contrast, if the signal strength of the laser light L remains stable at a predetermined value (8 V in Figure 6) while the signal strength of the thermal radiation light 63 remains below the lower limit of a predetermined allowable range (4 to 6 V in Figure 6), it is determined that a processing defect has occurred in the workpiece W.

[0072] Specifically, when two workpieces W are overlapped and welded together, if a gap occurs between the two workpieces W, the surface temperature of the workpieces W decreases due to the gap, and the thermal radiation light 63 tends to decrease. In other words, by using the rate of decrease from the thermal radiation light PD value during normal laser processing as an index, it is possible to detect processing defects in the workpieces W. The type of trouble in this case is the occurrence of a gap between the two workpieces W.

[0073] In the example of a processing defect shown in Figure 6, the signal strength of the laser light L is stable, and the thermal radiation light 63 from the workpiece W is below the lower limit of the allowable range, so it can be determined that there is a defect in the condition of the workpiece W.

[0074] In this way, by monitoring the emitted light 60, it is possible to perform quality control, for example, quantify the degree of reproducibility of the welding state, and further determine what kind of defect is causing the trouble.

[0075] Specifically, processing defects are detected from the increase or decrease in the waveform or the occurrence of peaks compared to normal laser processing, and the type of problem, such as focus position deviation, burn-through, or spatter, is determined.

[0076] Here, the method for determining defects may be, for example, a threshold determination method set by an operator, a determination method using an AI algorithm using machine learning in which learning data is prepared in advance, or a determination method using deep learning in which the method is updated based on the determination results of the learning data.

[0077] In the examples shown in FIGS. 4 to 6, the voltage range is set to 0 to 10 V, but the voltage range may be set to an appropriate range depending on the S / N ratio.

[0078] Furthermore, when detecting processing defects using a threshold judgment method, the welding waveform during normal laser processing is detected multiple times, and upper and lower threshold values ​​shown by the dashed lines in FIGS. 4 to 6 are set taking into consideration the waveform variation and the processing tolerance of the workpiece W, and waveforms that fall within this tolerance range are deemed to be non-defective.

[0079] 4 to 6, a normal value is about ±1 V from when the laser stabilizes, but this set value differs depending on the processing conditions and required processing accuracy of the workpiece W. Also, the above-mentioned changes in the waveforms of the reflected light 61, plasma light 62, and thermal radiation light 63 are merely examples, and the response of the waveforms differs depending on the object to be processed, welding conditions, etc.

[0080] The second determination device 40 has a defect determiner 41 and a display terminal 45. The defect determiner 41 determines the location of a defect in the laser processing machine 10.

[0081] The defect determiner 41 receives the oscillator output PD value, the fiber incident scattered light PD value, the fiber exit scattered light PD value, the head output PD value, and the head scattered light PD value from the laser processing machine 10.

[0082] The malfunction determiner 41 receives the workpiece ID, the reflected light PD value, the plasma light PD value, the thermal radiation light PD value, the determination result, and information indicating the type of trouble from the first determination device 30 side.

[0083] The various data input to the malfunction determiner 41 is stored in a storage unit (not shown) within the malfunction determiner 41. When storing the various data in the malfunction determiner 41, calculations such as taking a moving average of the various data or the maximum value per fixed time period may be performed. The malfunction determiner 41 accumulates the various data that are monitoring information and analyzes trends.

[0084] The fault determiner 41 is highly customizable and may be on-premises, where hardware is installed and managed within the user's facility, or may be cloud-based, where hardware management is not required.

[0085] The data stored in the defect determiner 41 may be either analog or digital data. The data transmission method may be a relatively simple serial transmission method or a parallel method with a high communication speed and a large communication volume.

[0086] If the stored judgment result is NG, the malfunction judger 41 judges the malfunction location by monitoring the relative ratio and time change of the oscillator output PD value, the head output PD value, and the head scattered light PD value. Note that the judgment criteria for the judgment result being NG are merely examples, and the reference values ​​change depending on the maximum output of the laser oscillator 11 and the usage environment.

[0087] The failure determiner 41 stores the maximum fiber-entered scattered light PD value and the maximum fiber-exited scattered light PD value at which the transmission fiber 12 may fail, and the maximum head scattered light PD value at which the processing head 20 may fail.

[0088] The display terminal 45 is configured by, for example, a monitor. The display terminal 45 displays the determination result determined by the defect determiner 41. The determination result displays the location that the worker should investigate with priority.

[0089] The second judgment device 40 simultaneously monitors the condition of the workpiece W, the processing head 20, and the laser oscillator 11 in association with each other, making it possible to detect processing defects in the workpiece W and to confirm at a glance where the cause is occurring.

[0090] Furthermore, the welding state of the workpiece W, the state of the processing head 20, and the state of the laser oscillator 11 are linked to the workpiece ID and stored in the second determination device 40, and trends are analyzed. This makes it possible to manage maintenance schedules and prevent malfunctions before they occur.

[0091] <Determination of Abnormal Location> Hereinafter, a case where a processing defect occurs due to poor penetration of the workpiece W during laser processing will be considered.

[0092] As shown in FIG. 7, in step S10, laser processing of the workpiece W is completed, and the process proceeds to step S11.

[0093] In step S11, a determination is made as to whether the workpiece W is defectively machined, and the process proceeds to step S12.

[0094] In step S12, various data detected by the laser processing machine 10 and the first determination device 30 are transmitted to the second determination device 40, and the process proceeds to step S13.

[0095] In step S13, it is determined whether the determination result is OK. If the determination in step S13 is "YES", the process branches to step S14. If the determination result is NG, that is, if the determination in step S13 is "NO", the process branches to step S15.

[0096] In step S14, the next workpiece W is processed, and the process ends.

[0097] In step S15, since the determination result is NG, the defective part is identified, and the process proceeds to step S16.

[0098] Specifically, the reflected light 61 tends to increase when there is insufficient penetration of the workpiece W. On the other hand, it is known that the reflected light 61 also increases when the optical components in the machining head 20 deteriorate, regardless of the degree of penetration of the workpiece W.

[0099] Therefore, simply detecting an increase in the reflected light 61 in the spectroscopic device 31 does not allow one to determine whether the increase in the reflected light 61 is due to a processing defect in the workpiece W or to deterioration of the optical components in the processing head 20.

[0100] Therefore, the first determination device 30 monitors the transition of the head scattered light PD value for each processing. The head scattered light PD value increases in accordance with the deterioration of the optical components (e.g., the collimator lens 21, the dichroic mirror 22, the first condenser lens 23, etc.) in the processing head 20. Therefore, when the reflected light PD value and the head scattered light PD value both increase, it is considered that the increase is due to the deterioration of the optical components in the processing head 20.

[0101] Furthermore, for example, by arranging a plurality of fourth detectors 54 so as to surround the first condenser lens 23, it is possible to suppress variations in scattered light due to deteriorated parts of the first condenser lens 23.

[0102] On the other hand, when only the reflected light PD value is increasing, it is considered that a processing defect in the workpiece W has occurred.

[0103] The process of identifying the defective part in step S15 will be described in detail with reference to the flowchart shown in FIG.

[0104] In step S16, the evaluation result of the work W and the defect identification result are displayed on the display terminal 45, and the process ends.

[0105] <Identifying the defective area> When a processing defect due to insufficient penetration of the workpiece W is detected, it is determined based on the head output PD value whether the cause of the processing defect is due to the workpiece W or the laser processing machine 10.

[0106] Specifically, when the head output PD value of the processing head 20 in the laser processing machine 10 has decreased and it is determined that the processing defect is caused by the laser processing machine 10, the defective location in the laser processing machine 10 is identified from the oscillator output PD value, the fiber incident scattered light PD value, the fiber exit scattered light PD value, the head output PD value, and the rate of change of the head scattered light PD value.

[0107] As shown in FIG. 8, in step S20, the defect determiner 41 starts defect determination for identifying the defect location, and the process proceeds to step S21.

[0108] In step S21, it is determined whether the output of the processing head 20 has decreased. If the determination in step S21 is "YES," the process branches to step S22. In other words, if the head output PD value has decreased, it can be determined that the processing defect is caused by the laser processing machine 10.

[0109] If the determination in step S21 is "NO", the process branches to step S23. In other words, if the head output PD value has not decreased, it can be determined that the machining defect is caused by the workpiece W side.

[0110] In step S22, the condition of the workpiece W is investigated. That is, since a machining defect has occurred even though the output of the machining head 20 has not decreased, it is presumed that the condition of the workpiece W is the cause of the machining defect, and the result is displayed on the display terminal 45. This prompts the worker to investigate the workpiece W. If, as a result of investigating the workpiece W, an abnormality is found in the workpiece W or the surrounding jigs, the workpiece W is replaced or repaired.

[0111] In step S23, a malfunction of the laser processing machine 10 is estimated. The malfunction of the laser processing machine 10 is estimated based on the table shown in Fig. 9. If the detection results of each detector correspond to judgment item No. A in Fig. 9, the process branches to step S24. If the detection results correspond to judgment item No. B in Fig. 9, the process branches to step S25. If the detection results correspond to judgment item No. C or No. D in Fig. 9, the process branches to step S26. If the detection results correspond to judgment item No. E in Fig. 9, the process branches to step S27.

[0112] In this way, by comparing the rate of decrease in the head output PD value on the output side of the laser light L with the rate of decrease in the oscillator output PD value on the input source side of the laser light L, it is possible to isolate the location within the laser processing machine 10 where the output decrease has occurred.

[0113] In step S24, since there is a high possibility that a malfunction has occurred in the laser oscillator 11, the laser oscillator 11 is inspected, and the process proceeds to step S28.

[0114] Specifically, if the output reduction rate of the head output PD value and the oscillator output PD value is the same, it can be assumed that the cause of the output reduction is the laser oscillator 11. Therefore, a message indicating that the laser oscillator 11 should be investigated is displayed on the display terminal 45.

[0115] In step S28 after branching to step S24, it is determined whether there is a margin for increasing the output of the laser oscillator 11. If the determination in step S28 is "YES," the process branches to step S29, where the worker increases the output of the laser oscillator 11 by the amount that was reduced. If the determination in step S28 is "NO," that is, if the output of the laser oscillator 11 cannot be increased any further, the process branches to step S30, where the laser oscillator 11 is replaced.

[0116] In step S25, since there is a high possibility that a malfunction has occurred in the laser oscillator 11 and the transmission fiber 12, the laser oscillator 11 and the transmission fiber 12 are inspected, and the process proceeds to step S28.

[0117] Specifically, if the head output PD value is lower than the oscillator output PD value, it can be assumed that the cause of the output drop exists in both the laser oscillator 11 and the transmission fiber 12, as well as in the surrounding area.

[0118] Furthermore, the location of the cause of the output reduction can be further identified from the rate of change of the PD value of the scattered light incident on the fiber and the PD value of the scattered light emitted from the fiber.

[0119] For example, if the value of the scattered light PD incident on the fiber increases, it is possible that the coupling efficiency of the laser light L emitted from the laser oscillator 11 to the transmission fiber 12 is reduced.

[0120] At this time, a message is displayed on the display terminal 45 indicating that the coupling portion between the laser oscillator 11 and the transmission fiber 12 should be inspected.

[0121] The worker adjusts the optical axis between the laser oscillator 11 and the transmission fiber 12 and checks whether the rate of decrease in the head output PD value is restored to the same level as the rate of decrease in the oscillator output PD value.

[0122] In step S28 after branching to step S25, if the head output PD value does not recover to the same extent as the oscillator PD value, it is determined whether there is a margin for increasing the output of the laser oscillator 11.

[0123] For example, if the fiber incident scattered light PD value increases by 1.2 times from the initial value and increases to 2.0 times, the risk of failure of the laser oscillator 11 or the transmission fiber 12 becomes so high that it becomes unusable.

[0124] In this case, if it is allowed that the value of the scattered light PD incident on the fiber may increase up to 1.8 times the initial value with some margin, the determination in step S28 becomes "YES" and the process branches to step S29. In step S29, since there is some margin in the upper threshold value of the scattered light PD incident on the fiber, the output of the laser oscillator 11 is increased.

[0125] If the determination in step S28 is "NO," that is, if the output of the laser oscillator 11 cannot be increased any further, the process branches to step S30, where replacement of the transmission fiber 12 and the laser oscillator 11 is performed.

[0126] In step S26, since there is a high possibility that a problem has occurred in the transmission fiber 12, the transmission fiber 12 is inspected, and the process proceeds to step S28.

[0127] Specifically, if the fiber output scattered light PD value increases, deterioration of the optical components at the output end of the transmission fiber 12 is considered.

[0128] At this time, a message indicating that the output end of the transmission fiber 12 should be inspected is displayed on the display terminal 45.

[0129] In step S28 after branching to step S26, it is determined whether there is a margin for increasing the output of the laser oscillator 11.

[0130] For example, it is assumed that the fiber output scattered light PD value has increased by 1.2 times from the initial value, and if it increases to 2.0 times, the risk of failure of the transmission fiber 12 becomes so great that it becomes unusable.

[0131] In this case, if it is allowed that the value of the scattered light PD emitted from the fiber may increase up to 1.8 times the initial value with some margin, the determination in step S28 becomes "YES" and the process branches to step S29. In step S29, since there is some margin in the upper threshold value of the scattered light PD emitted from the fiber, the output of the laser oscillator 11 is increased.

[0132] If the determination in step S28 is "NO", that is, if the output of the laser oscillator 11 cannot be increased any further, the process branches to step S30, where the transmission fiber 12 is replaced.

[0133] In step S27, since there is a high possibility that a malfunction has occurred in the machining head 20, the machining head 20 is inspected, and the process proceeds to step S28.

[0134] Specifically, if the head scattered light PD value increases, deterioration of the optical components of the processing head 20 may be the cause.

[0135] However, since the head scattered light PD value depends on the magnitude of the laser incident light, it is evaluated based on the increase or decrease when normalized with the head output PD value.

[0136] If the normalized head scattered light PD value has increased, a message indicating that the processing head 20 should be inspected is displayed on the display terminal 45 .

[0137] In step S28 after branching to step S27, it is determined whether there is a margin for increasing the output of the laser oscillator 11.

[0138] For example, it is assumed that the head scattered light PD value has increased by 1.2 times from the initial value, and if it increases to 2.0 times, the risk of failure of the machining head 20 increases and it becomes unusable.

[0139] In this case, if there is a margin for increasing the output of the laser oscillator 11 and the head-scattered light PD value is allowed to increase by up to 1.8 times its initial value, the determination in step S28 becomes "YES" and the process branches to step S29. In step S29, when the normalized head-scattered light PD value does not recover, if there is a margin for error in the upper limit threshold of the head-scattered light PD value, the output of the laser oscillator 11 is increased.

[0140] If the determination in step S28 is "NO," that is, if the output of the laser oscillator 11 cannot be increased any further, the operator replaces the processing head 20. For example, the operator cleans or replaces the protective glass of the processing head 20.

[0141] As described above, if the investigation reveals that replacement work is necessary, the worker will perform the replacement work in the following order, taking into account the required work time and cost: workpiece W and peripheral jigs, machining head 20, transmission fiber 12, and laser oscillator 11.

[0142] The worker replaces parts or performs maintenance on the area that is presumed to be the cause of the machining defect, and then performs test machining.

[0143] For example, waveform data that can be evaluated as a non-defective product is detected 10 times, and the reflected light PD value, plasma light PD value, thermal radiation light PD value, and head output PD value at that time are transmitted to and stored in the first determination device 30. Meanwhile, the oscillator output PD value, fiber incident scattered light PD value, fiber exit scattered light PD value, head output PD value, and head scattered light PD value are transmitted to and stored in the second determination device 40. This sets a new determination reference value.

[0144] The number of times the waveform data is detected is merely an example, and varies depending on the workpiece W and the user's wishes.

[0145] When an operator investigates the cause of a processing defect based on the judgment result of the second judgment device 40, by linking the workpiece ID, construction time, judgment result, type of trouble, output of the laser oscillator 11, output of the processing head 20, and degree of deterioration of the processing head 20, it becomes possible to determine at a glance which workpiece W the processing defect occurred for, when, and how.

[0146] Furthermore, the output waveform of the laser light L at that time, the waveform of the reflected light 61, the waveform of the plasma light 62, and the waveform of the thermal radiation light 63 can be easily accessed, enabling quick cause analysis.

[0147] In this embodiment, the judgment information of the workpiece W (judgment result and type of trouble) and information of the laser processing machine 10 (output of the laser oscillator 11, output of the processing head 20, and degree of deterioration of the optical components of the processing head 20) can be stored simultaneously in the second judgment device 40, so it is possible to clarify how much the laser output at which part of the laser processing machine 10 needs to decrease will cause processing defects.

[0148] Therefore, it is possible to set processing conditions with appropriate tolerances, and to manage the maintenance schedule for the laser processing machine 10 to prevent malfunctions before they occur.

[0149] --Modification of this embodiment-- Hereinafter, the same parts as those in the above embodiment will be denoted by the same reference numerals, and only the differences will be described.

[0150] As shown in Figure 10, the processing head 20 has a collimator lens 21, a first condenser lens 23, a reflecting mirror 24, a second condenser lens 25, a transmitting mirror 26, a first detector 51, and a fourth detector 54.

[0151] The collimating lens 21 collimates the laser light L transmitted through the transmission fiber 12 .

[0152] The transmission mirror 26 transmits most of the laser light L collimated by the collimator lens 21, while reflecting a portion of the laser light L.

[0153] The first detector 51 is disposed at a position where it can detect the laser light L reflected by the transmission mirror 26. The first detector 51 is a head output PD sensor that detects the light intensity of the laser light L emitted from the laser processing machine 10.

[0154] The first condenser lens 23 condenses the laser light L that has passed through the transmission mirror 26. The laser light L condensed by the first condenser lens 23 is emitted toward the workpiece W.

[0155] The fourth detector 54 is disposed on the output side of the first condenser lens 23. Specifically, the fourth detector 54 is disposed near the first condenser lens 23 and along the inner wall surface of the housing of the machining head 20. The fourth detector 54 is a head scattered light PD sensor that detects the light intensity of scattered light on the output side of the machining head 20.

[0156] When laser light L is emitted from the machining head 20 toward the workpiece W, emitted light 60 is emitted from the workpiece W. The emitted light 60 is reflected by the transmission mirror 26. The emitted light 60 reflected by the transmission mirror 26 is reflected by the reflection mirror 24 and then focused by the second focusing lens 25. The emitted light 60 focused by the second focusing lens 25 enters the spectrometer 31 of the first determination device 30 via the transmission fiber 12.

[0157] Other Embodiments The above-described embodiment may be configured as follows.

[0158] In this embodiment, the first detector 51, the second detector 52, the third detector 53, the fourth detector 54, the fifth detector 55, and the sixth detector 56 are configured with photodiodes, but the present invention is not limited to this. For example, instead of photodiodes, a CCD (Charge Coupled Device) sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor, a spectrometer, or an acoustic sensor may be used.

[0159] As described above, the present invention has the highly practical effect of making it possible to easily identify the cause of a problem when it occurs during laser processing, and is therefore extremely useful and has high industrial applicability.

[0160] REFERENCE SIGNS LIST 1 Laser processing system 10 Laser processing machine 11 Laser oscillator 12 Transmission fiber 12a Transmission fiber 20 Processing head 30 First determination device 40 Second determination device 51 First detector 52 Second detector 53 Third detector 54 Fourth detector 55 Fifth detector 56 Sixth detector 60 Emitted light L Laser light W Workpiece

Claims

1. A laser processing system comprising: a laser processing machine which emits laser light toward a workpiece; a first detector which detects the light intensity of the laser light emitted from said laser processing machine; a second detector which detects the light intensity of light emitted from said workpiece during laser processing; and a first judgment device which judges whether there is a problem with the laser processing machine or the condition of the workpiece based on the light intensities detected by said first detector and said second detector, respectively.

2. A laser processing system according to claim 1, wherein the laser processing machine has a laser oscillator which oscillates the laser light, and a processing head which emits the laser light oscillated by the laser oscillator towards the workpiece, and is further equipped with a third detector which detects the light intensity of the laser light oscillated by the laser oscillator, and a fourth detector which detects the light intensity of scattered light on the emission side of the processing head, and a second determination device which determines whether or not there is a malfunction in the laser oscillator or the processing head based on the light intensities detected by the first detector, the third detector and the fourth detector, respectively.

3. A laser processing system according to claim 2, wherein the laser processing machine has a transmission fiber that transmits the laser light oscillated by the laser oscillator to the processing head, and is equipped with a fifth detector that detects the light intensity of scattered light on the incident side of the transmission fiber, and a sixth detector that detects the light intensity of scattered light on the exit side of the transmission fiber, and the second determination device determines whether or not there is a defect in the transmission fiber based on the light intensities detected by the fifth detector and the sixth detector, respectively.

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