JP4757557B2 - Laser processing head - Google Patents

Description

The present invention relates to an optical fiber and a laser processing apparatus using a laser processing head that receives laser light from an optical fiber and irradiates a workpiece .

  In recent years, high-power lasers have been widely used in the field of processing industries such as welding, cutting or surface treatment. In particular, laser welding is becoming more and more important because it enables high-precision and high-speed machining, low thermal strain on the workpiece, and high-level automation. Further, remote laser welding using an optical fiber is possible, and it is not uncommon for welding to be performed at a remote location, for example, 30 m to 50 m away from the laser oscillator. A general laser welding machine has a function to monitor the laser output of the laser light oscillated and output from the built-in laser oscillator. If there is an abnormality in the laser oscillator, the situation is detected immediately by monitoring the laser output. It can be done.

  However, in remote laser processing, the laser beam oscillated and output from the laser oscillator is irradiated to the workpiece at a remote location via an optical system such as an incident unit, an optical fiber, and a laser processing head. Even if the laser output at the processing point of the workpiece is abnormally lowered due to dirt, damage, or deterioration of some optical parts on the laser beam path, the main body cannot grasp it. For this reason, it is necessary to discover defects only after the inspection after processing (appearance inspection, destructive inspection, nondestructive inspection, etc.), and there is a problem in production management (such as frequent occurrence of defective products). Moreover, the maintenance method (checking, cleaning, repair, parts replacement, etc.) of each part regularly in a short cycle has to stop the production line frequently for maintenance work, and in terms of production efficiency There's a problem. Conventionally, the output state of the laser light emitted from the laser processing head is also monitored by measurement with a laser power meter. However, this method is also performed with laser processing stopped, and there is a disadvantage that productivity is lowered.

The present invention has been made in view of the above-described problems of the prior art. In an optical fiber transmission system, the output state of laser light, the state of optical components that allow laser light to pass through, and the state of the workpiece are in-line. It is an object to provide a laser processing apparatus that accurately monitors and improves the production control, quality control, and production efficiency of laser processing .

In order to achieve the above object, the laser processing apparatus of the present invention transmits a laser beam oscillated and output from a laser oscillation unit to a laser processing head via an optical fiber for laser transmission, and receives the laser beam from the laser processing head. A laser processing apparatus for performing desired laser processing by condensing and irradiating the laser beam toward a workpiece, wherein a laser emission port is provided on a first surface facing a processing point of the workpiece, and the first An optical fiber connecting portion for attaching the end portion of the optical fiber to the second surface opposite to the surface, and the laser beam emitted from the end surface of the optical fiber is used as a processing point of the workpiece. A head main body that contains an optical lens for condensing and attaches a protective glass to the laser emission port, a laser output measurement unit for measuring the output of the laser light before entering the optical fiber, A laser beam measuring unit attached to the head body for measuring the light intensity of the laser beam emitted from the end face of the optical fiber, and reflected from the processing point of the workpiece into the laser emission port. A reflected light measuring unit attached to the head body for measuring the light intensity of the reflected light, a measured value of the laser light output obtained from the laser output unit, and the laser light obtained from the laser light measuring unit. A first monitor unit that monitors whether the optical fiber is normal based on a measured value of light intensity, a measured value of the laser light intensity obtained from the laser light measuring unit, and the reflection Based on the measured value of the light intensity of the reflected light obtained from the light measuring unit, it is monitored whether the surface state of the workpiece is normal or whether the protective lens is abnormally dirty. Second And a monitor unit.

In the above-described configuration, the laser output before the laser beam is incident on the optical fiber is measured by the laser output measuring unit on the laser oscillator unit side, and the light intensity (laser output) immediately before the laser beam is emitted in the laser processing head Is measured by the laser light measurement unit, and the light intensity of the reflected light from the processing point of the workpiece is measured by the reflected light measurement unit, and each measurement value is combined and analyzed by the first and second monitor units. Therefore, it is possible to accurately monitor in-line the state of the laser optical system including the optical fiber, the laser output state before and after the processing point of the workpiece is irradiated, the surface state of the workpiece, or the contamination state of the protective lens. it can. That is, if an abnormality is detected from the measurement result of the laser beam measurement unit even though there is no abnormality in the measurement result of the laser output measurement unit, the cause is damage or deterioration of the optical system in front of the laser irradiation unit, that is, the optical fiber. Monitoring information can be obtained, and when no abnormality is detected from the measurement of the laser light measurement unit, and when an abnormality is detected from the measurement of the reflected light measurement unit, the protective lens is considerably dirty or the workpiece Monitoring information can be obtained.

According to a preferred aspect of the present invention, the laser beam oscillated and output from the laser oscillation unit is a pulsed laser beam, and the reflected light measurement unit starts from a first time point a predetermined time after the rising edge of the pulsed laser beam. The period from the falling edge of the pulsed laser beam to the second time before the predetermined time is used as the calculation interval, and the average value, integral value, maximum value, or peak value of the reflected light intensity obtained in this calculation interval is used as the measurement value. To do. According to such a configuration, accurate monitoring can be performed even if the pulse waveform of the reflected light is considerably corrupted or the overshoot waveform is included in the rise of the pulse laser beam.
In another preferable aspect, the second monitor unit calculates a ratio of the light intensity measurement value of the reflected light to the light intensity measurement value of the laser light, and monitors how the ratio decreases with time. This makes it possible to display and output a determination result that prompts inspection or inspection in a timely manner.

  According to a preferred aspect of the present invention, the laser light measurement unit and / or the reflected light measurement unit is also attached to the second surface of the head body. As described above, in the configuration in which the optical fiber, the laser light measurement unit, and / or the reflected light measurement unit are connected to or attached to the upper surface of the laser processing head, the optical fiber and the signal line are concentrated above the head and are laid over or laid. Therefore, the mounting or mounting of the machining head is easy, the space efficiency near the machining site and the usability are improved, and the maintenance performance of the machining head itself and the safety at the time of laser leakage are also improved.

  According to a preferred aspect of the present invention, the optical fiber connection portion is provided at a position offset from the optical axis passing through the optical lens and the laser emission port, and the laser light emitted from the end surface of the optical fiber is reflected toward the optical lens. For this purpose, the head main body has one or a plurality of first mirrors, and at least one of the first mirrors is arranged coaxially with the optical lens when viewed from the laser emission port side. In such a configuration, the optical fiber connection portion, the laser light measurement portion, and the reflected light measurement portion can be arranged side by side in an efficient layout on the upper surface of the head. Preferably, the reflected light measurement unit may be arranged coaxially with the optical lens when viewed from the laser emission port side.

  According to a preferred aspect, a collimating lens is provided between the terminal surface of the optical fiber and the first mirror for converting the laser light emitted from the terminal surface of the optical fiber into parallel light. In addition, a second mirror for reflecting the light leaking to the back side of the first mirror corresponding to the laser beam toward the laser beam measurement unit is provided in the head body.

  As a preferred aspect, the laser beam measurement unit includes a first photoelectric conversion element that receives the leakage light from the first mirror and generates a first electric signal that represents the light intensity. The reflected light measurement unit includes a second photoelectric conversion element that receives reflected light from a processing point of the workpiece and generates a second electric signal representing the light intensity. In this case, the electrical signal output from the first and / or second photoelectric conversion element may be transmitted to a remote monitor device via the signal line.

  As another preferable aspect, the laser light measurement unit includes a first monitoring optical fiber that receives leakage light from the first mirror on one end surface and transmits the leakage light to a remote first photoelectric conversion element. The reflected light measuring unit also includes a second monitoring optical fiber that receives reflected light from a processing point of the workpiece on one end surface and transmits the received light to a remote second photoelectric conversion element. In this case, the laser processing head and the remote monitoring device are connected by the first and / or second monitoring optical fibers.

According to the laser processing apparatus of the present invention, with the configuration and operation as described above, in the optical fiber transmission system, the output state of the laser light, the state of the optical component that passes the laser light, and the state of the workpiece are accurately in-line. Monitoring can improve production control, quality control, and production efficiency of laser processing .

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows the overall configuration of a laser processing apparatus according to an embodiment of the present invention. This laser processing apparatus has, as a basic configuration, a laser processing machine main body 10 including a laser oscillator 10a that oscillates and outputs laser light for laser processing (for example, pulsed laser light) LB, and laser processing disposed at a desired processing location. Controls the head 12, the optical fiber 14 that optically connects the laser processing machine main body 10 and the laser processing head 12, the monitor main body 16 that performs necessary signal processing and display output for monitoring, and the entire system sequence. Controller 18.

In this laser processing apparatus, the laser beam LB generated or oscillated and output by the laser oscillator 10 a in the laser processing machine main body 10 is transmitted to the remote laser processing head 12 through the optical fiber 14, and the workpiece from the laser processing head 12. (Workpiece) Condensed and irradiated toward the processing point WP of W. For example, in the case of welding, at the processing point WP of the workpiece W, two members that are overlapped (or abutted) with each other are melt-bonded by the laser energy of the laser beam LB. The monitor main body 16 is an electric signal (light intensity detection signal) S _L generated from two monitoring photodetectors, that is, a laser photodetector 26 and a reflected photodetector 28, which are provided in the laser processing head 12 described later. , S _R , the measured values and pass / fail judgments regarding the state of the optical components on the laser transmission path, the laser output state of the laser beam LB at the processing point WP, the processing quality, and the like are displayed and output.

  The laser oscillator 10a has, for example, a laser oscillator of a solid laser such as a YAG laser, a fiber laser, or a disk laser, or a laser oscillator of a gas laser such as a carbon dioxide gas laser. In the laser processing machine main body 10, an incident unit (not shown) for condensing and incident the laser beam LB emitted from the laser oscillator 10 a onto one end surface of the optical fiber 14, or the laser beam LB immediately before entering the optical fiber 14. A laser output measuring unit (not shown) for measuring the laser output is also provided. The optical fiber 14 may be an arbitrary multimode optical fiber, for example.

  The laser processing head 12 has a hollow housing or head main body 20 made of, for example, aluminum, and an optical lens, a mirror, etc., which will be described later, are arranged at a predetermined position in the head main body 20. In the head main body 20, a laser emission port 22 is provided on the lower surface of the main body facing the processing point WP of the workpiece W, and a terminal portion of the optical fiber 14 can be attached to and detached from the upper surface of the main body opposite to the laser emission port 22. An optical fiber connecting portion 24 for attachment, the laser light detector 26 for monitoring and the reflected light detector 28 are attached.

  FIG. 2 shows a specific configuration of the laser processing head 12 in this embodiment. A cylindrical portion 29 extending downward from the central portion of the lower surface of the head main body 20 is formed, and a protective glass 30 is attached to the laser emission port 22 located at the lower end portion of the cylindrical portion 29, and is focused near the inner depth of the protective glass 30. A lens 32 is arranged.

A vent mirror 34 is disposed immediately above the focusing lens 32 at a substantially central position inside the head main body 20 with its reflecting surface 34a inclined downward at an angle of 45 °, for example, and further directly above it, the reflected light detector 28. Is arranged with its light receiving surface facing vertically downward. Here, the reflected light detector 28 is attached to a sensor attachment opening provided on the upper surface of the head main body 20. An optical filter 35 is disposed between the vent mirror 34 and the reflected light detector 28. The optical filter 35 selects light having a specific wavelength (for example, the same wavelength as the laser light LB) from the reflected light R _LB transmitted from the processing point WP of the workpiece W through the protective glass 30, the focusing lens 32, and the vent mirror 34. Includes a filter that automatically passes.

  On the upper surface of the head body 20, a position shifted laterally from the reflected light detector 28 on the head center axis line, that is, a position offset laterally (right side in FIG. 2) from the optical axis passing through the vent mirror 34 and the focusing lens 32. Thus, the cylindrical optical fiber mounting portion 24 extends vertically upward. At the upper end of the optical fiber mounting portion 24, a connector or receptacle 36 for receiving the terminal portion of the optical fiber 14 in a detachable manner is provided.

  A collimating lens 38 for making the laser beam LB emitted radially from the end surface 14 a of the optical fiber 14 into parallel light is disposed inside the optical fiber mounting portion 24, and a vent mirror is provided directly below the collimating lens 38. 40 is arranged with its reflecting surface 40a inclined obliquely upward at an angle of 45 °, for example. Here, the reflecting surface 40a of the vent mirror 40 is optically opposed to the reflecting surface 34a of the vent mirror 34, and the laser light LB from the end surface 14a of the optical fiber 14 is horizontally routed from the vertical direction by the vent mirror 40. The light beam is incident on the bent mirror 32 after being bent at right angles to the direction, and is incident on the focusing lens 32 by bending the optical path perpendicularly downward from the horizontal direction. The focusing lens 32 focuses the laser beam LB on the processing point WP of the workpiece W.

On the upper surface of the head main body 20, the laser light detector 26 is disposed with its light receiving surface facing vertically downward at a position offset to the opposite side of the optical fiber mounting portion 24 along with the reflected light detector 28. Here, the laser light detector 26 is attached to a sensor attachment opening provided on the upper surface of the head main body 20. A vent mirror 42 is disposed directly below the laser light detector 26 with its reflecting surface 42a facing obliquely upward at an angle of 45 °, for example. Here, the reflecting surface 42 a of the vent mirror 42 is optically opposed to the reflecting surface 40 a of the vent mirror 40 via the vent mirror 34, and the laser light LB from the end surface 14 a of the optical fiber 14 is transmitted from the vent mirror 34. The light _MLB leaked to the rear (left side) of the vent mirror 34 upon reflection is incident on the vent mirror 42, and the vent mirror 42 bends the optical path from the horizontal direction to the vertical upper direction at a right angle to receive the laser light detector 26. It is incident on the surface. Between the vent mirror 34 and the vent mirror 42, an optical filter 44 including a filter that selectively passes the wavelength of the laser light LB, an ND filter for attenuation, and the like is disposed.

Laser beam detector 26 has a photoelectric conversion element, for example a photodiode, an electric signal representing the light intensity from the bent mirror 34 and receives leaked light M _LB of the laser beam LB leaking horizontally backward S _L Is generated. Here, the light intensity of the leakage light M _LB is the light intensity or laser power P _L of the laser beam LB immediately after being emitted from the end face of the optical fiber 14 in a fixed proportional relationship. The output signal (laser light intensity detection signal) S _L of the laser light detector 26 is sent to the monitor device main body 16 via the signal line 46.

The reflected light detector 28 has a photoelectric conversion element, for example, a photodiode, and receives the reflected light R _LB passing through the vent mirror 34 vertically upward from the optical lens 32 and represents an electric signal S _R representing the light intensity. Is generated. Here, the light intensity of the reflected light beam R _LB depends on the surface reflectance at the processing point WP of the workpiece W, the degree of penetration, etc., but at least has a certain proportional relationship with the laser output at the processing point WP. The output signal (reflected light intensity detection signal) S _R of the reflected light detector 28 is sent to the monitor device main body 16 via the signal line 48.

  In FIG. 1, a monitor device body 16 includes a panel input unit 16a including keys or buttons on a front panel and a panel display unit 16b such as a liquid crystal screen, and performs various arithmetic processes necessary for monitoring according to the present embodiment. Built-in electronic circuit. The electronic circuit built in the monitor device body 16 includes, for example, a microcomputer, and functionally includes a control unit 50, a laser light measurement calculation unit 52, a reflected light measurement calculation unit 54, and comparison units 56 and 58 as shown in FIG. The monitor section setting section 60, the calculation section setting section 62, and the like. The control unit 50 performs a man-machine interface with the user through the panel input unit 16a and the panel display unit 16b, and also synchronizes timing signals from the main unit 10 every time the laser beam LB is oscillated and output from the laser welding machine main unit 10. The controller 18 receives a laser processing condition or condition number from the controller 18 and gives a necessary control signal or data to each part in the unit.

In FIG. 3, a laser beam measurement calculation unit 52 terminates the optical fiber 14 in the laser processing head 12 based on the light intensity detection signal S _L sent from the laser beam detector 26 mounted on the laser irradiation unit 12. A light intensity measurement value P _L of the laser beam LB immediately after being emitted from the surface is obtained. In general, the laser beam LB for laser welding is oscillated and output as a pulsed laser beam having a substantially rectangular laser output waveform as shown in FIG. When such a pulse laser beam LB is passed through the optical fiber 14, the amplitude or light intensity (laser output) is attenuated during fiber transmission as shown in FIG. The substantially rectangular laser output waveform is generally maintained. The laser light measurement calculation unit 52 obtains a peak value or an average value of the light intensity detection signal S _L from the laser light detector 26 and multiplies it by a predetermined coefficient to obtain a light intensity measurement value P immediately after the laser light LB is emitted from the fiber. _{Find L.} The laser light intensity measurement value P _L obtained by the laser light measurement calculation unit 50 is given to the control unit 50 and also to both the comparison units 56 and 58. The control unit 50 may display and output the laser beam intensity measurement value P _L from the laser beam measurement calculation unit 50 as it is on the panel display unit 16b.

The comparison unit 56 is given a comparison reference value AP _L and a determination reference value J from the control unit 50. Here, the comparison reference value AP _L corresponds to the laser output setting value of the laser beam LB given from the controller 18 or the laser output measurement value of the laser beam LB given from the laser output measuring unit of the laser processing machine body 10. Yes. The comparison / determination unit 56 obtains a ratio or ratio (P _L / AP _L ) of the laser light intensity measurement value P _{L to} the comparison reference value AP _L and compares the ratio (P _L / AP _L ) with the determination reference value J. To do. The control unit 50 receives the comparison result from the comparison unit 56, and when the ratio (P _L / AP _L )> J, the laser beam LB immediately after being emitted from the end surface of the optical fiber 14 in the laser processing head 12 is obtained. When the laser output exceeds the reference value, that is, it is determined to be normal, and the ratio (P _L / AP _L ) ≦ J, the laser output of the laser beam LB is lower than the reference value, that is, is abnormal. Is determined.

  When the laser light detector 26 detects an abnormal drop in the laser output in this way, any optical component on the laser transmission path from the laser oscillator 10a as the laser oscillation source to the vent mirror 32 in the laser processing head 12 is selected. This is when there is dirt, damage, deterioration, etc. exceeding the tolerance. If there is an abnormality around the laser oscillator 10a, it is detected by monitoring by a laser output measuring unit in the laser processing machine body 10. Unless it is abnormal on the main body 10 side, the bent mirrors 40 and 32 are usually hardly contaminated / damaged / deteriorated, so it is determined that there is a cause (mainly damaged / deteriorated) of the optical fiber 14. Can be estimated. The control unit 50 may display and output the determination result through the panel display unit 16a, and may issue an appropriate alarm or message when the abnormality determination result is output. Furthermore, the determination result can also be sent to the controller 18.

Based on the light intensity detection signal S _R sent from the reflected light detector 42 mounted on the laser processing head 12, the reflected light measurement calculation unit 54 performs processing from the processing point WP of the workpiece W to the processing head 12 side during laser welding. obtaining a light intensity measurements P _R of the reflected light R _LB emitted to. In general, this type of reflected light R _LB is detected as a laser output waveform that is considerably deformed from a rectangle as shown in FIG. In this embodiment, a monitor interval setting unit 56 and a calculation interval setting unit 58 are provided, and the user can arbitrarily set and input a desired monitor interval T _M and calculation interval T _C through the panel input unit 16a. Yes.

Monitor interval T _M is, for example, FIGS. 5 and one as shown in FIG. 6 to be set to a period including only the pulse laser light (single shot) also possible, as shown in FIGS. 7 and 8 It is also possible to set a period including a plurality (multiple shots) of pulsed laser light. In the latter case (multiple shots), it is possible to evaluate pass / fail judgment for the entire pulse train (collective). The computation interval T _C is a second time point (t _c ) before the falling edge (t _d ) from the first time point (t _b ) after the desired time after the rising edge (t _a ) of the pulse laser beam. ) Can be set as _a section (t _{a to} t _b ). Actually, the reflected light R _LB from the workpiece W shows an unstable overshoot waveform due to the influence of the workpiece surface state at the time of rising of the pulse laser beam, and after it settles, the reflected light intensity corresponding to the original laser output Indicates. The reflected light measurement computation unit 54, in accordance with an instruction from the control unit 50 (or the user), in order to obtain the light intensity measurements P _R of the reflected light R _LB, a calculation interval T _C eg integral value E _R or the average value _PAV is calculated. The integral value E _R corresponds to the laser energy (joule) of the pulse laser beam. The average value P _AV may be an arithmetic average obtained by sampling the light intensity detection signal S _R at an appropriate period. Although not illustrated, it may be a light intensity measurements P _R with the maximum value or peak value in the calculation interval T _C. The monitoring and multiple shots of monitoring each pulse is basically only the length of the monitoring interval T _M to set the user is different, requires no special switching algorithm or hardware or software.

The light intensity measurement value P _R obtained by the reflected light measurement calculation unit 54 is given to the control unit 50 and also to the comparison unit 58. Control unit 50 may display output as it is a display panel 16b of the light intensity measurements P _R from the reflected light measurement computation unit 54. The comparison unit 58 is provided with the light intensity measurement value P _LB from the laser beam measurement calculation unit 52 as described above, and the control unit 50 determines the determination reference value D for normality / abnormality of the processing portion and the welding quality determination. A judgment reference value F and a required coefficient K are given. Here, the coefficient K is set according to the laser processing conditions (particularly the material of the workpiece W, etc.). The determination reference value D for determining the quality of welding corresponds to the laser output setting value of the laser beam LB given from the controller 18 or the laser output measurement value of the laser beam LB given from the laser output measuring unit of the welding machine body 10. in well, it may be set as the upper limit F _H and the lower limit value F _L.

For processing unit normal / abnormal determination, comparison unit 58 obtains the ratio or proportion of the reflected light intensity measurement P _R with respect to the laser beam intensity measurements P _LB immediately after the optical fiber emission (P _R / P _LB), the The ratio (P _R / P _LB ) is compared with the criterion value D. The control unit 50 receives the comparison result from the comparison unit 58, and when the ratio (P _R / P _LB )> D, the laser output at the processing point WP of the laser beam LB exceeds the reference value or threshold, that is, processing. Is determined to be normal (no abnormality), and when the ratio (P _R / P _LB ) ≦ D, the laser output of the laser beam LB at the processing point WP is lower than the reference value or threshold value, that is, processing It is determined that there is an abnormality in the part.

  As described above, when it is determined that there is an abnormality in the processing portion, there is an abnormality in the state of the workpiece W (particularly the surface state), or the optical components on the optical path in the laser processing head 12, that is, the vent mirrors 40 and 34, the focusing. This is a case where either the lens 32 or the protective lens 30 has dirt, damage, deterioration, etc. exceeding the tolerance. In any case, it is a scene where the laser processing should be stopped once and the processing portion should be inspected.

When an abnormality on the workpiece W side cannot be assumed, it can be determined or estimated that there is a cause on the optical component side. Usually, the vent mirrors 40 and 34 incorporated in the processing head 12 and the focusing lens 32 rarely have a cause (dirt, damage, deterioration, etc.), and the protective lens 30 facing the workpiece W is dirty. Most of them. In general, the contamination of the protective lens 30 increases with time. Therefore, it is also possible to monitor how the ratio (P _R / P _LB ) decreases with time. The control unit 50 may display and output a determination result urging inspection or inspection through the panel display unit 16a, and may issue an appropriate alarm or message when outputting the determination result of abnormality. Further, the determination result may be sent to the controller 18.

For welding quality determination, comparing unit 58 compares the reflected light intensity measurement P _R and the determination reference value F (upper limit F _H and the lower limit value F _L). Control unit 50 receives the comparison result from the comparison unit 58 determines that F _L <P _R <laser output at the processing point WP of the laser beam LB when the F _H is within the normal range welding good, P _R When ≦ F _L or P _R ≧ F _H, the laser output at the processing point WP of the laser beam LB is outside the normal range, and it is determined that the welding is defective. The control unit 50 displays and outputs the determination result about the quality of welding through the panel display unit 16 a or sends it to the controller 18. Furthermore, it is also possible to send the determination result or the reflected light intensity measurement values P _R for the laser output feedback control in the laser welding machine body 10.

In the monitor device body 16 described above, for processing unit normal / abnormal determination, the ratio between the laser light intensity measurements P _LB immediately after the optical fiber emission and the reflected light intensity measurement P _R in the comparison unit 58 (P _R / P _LB ) was obtained and compared with the criterion value D. However, as another approach, none of the laser light intensity measurements P _LB and the reflected light intensity measurement P _R by utilizing a certain point in a certain relationship between the laser power state at the processing point WP of the laser beam LB, the laser beam it is also possible from both sides of the intensity measurements P _LB and the reflected light intensity measurement P _R to evaluate the laser power condition of the work point comprehensively or complex.

As described above, in the laser processing apparatus of this embodiment, the two photodetectors 26 and 28 are attached to the laser processing head 12, and the laser processing apparatus 12 immediately after the light is emitted from the end face 14a of the optical fiber 14 in the processing head 12. The light intensity of the laser light LB is measured using the light detector 26 of the laser light measuring unit, and the light intensity of the light R _LB reflected from the workpiece W to the laser processing head 12 is measured by the light detector of the reflected light measuring unit. 28 was measured using a optical components through which a laser beam LB on the basis of the laser beam LB light intensity measurements P _LB and the light intensity measurement values P _R of the reflected light R _LB state, the workpiece W state, the laser output Optical measurement and pass / fail judgment can be made in-line regarding the status and the like, and useful monitoring information with high reliability can be provided to the user in terms of production management or quality control. In addition, since abnormalities and failures are discovered and reported in a timely manner, it is possible to minimize the time required to stop the production line for maintenance such as replacement of protective glass.

  Further, in the laser processing head 12 of this embodiment, the optical fiber 14, the laser light detector 26, and the reflected light detector 28 are all connected to or attached to the upper surface of the laser processing head 12, so that the optical fiber 14 and All of the signal lines 46 and 48 can be aggregated above the head and laid over or laid. This simplifies the mounting or mounting of the machining head 12 on a head support unit or robot arm (not shown), improves the space efficiency near the machining location and ease of use, and improves the maintainability of the machining head 12 itself. . Even if the laser light detector 26 or the reflected light detector 28 is opened for some reason and laser light is emitted from the processing head 12 to the outside, it leaks upward rather than to the side of the processing head 12. There is no fear of irradiating nearby workers, and it is excellent in terms of safety.

  Next, another embodiment of the present invention will be described with reference to FIGS.

  FIG. 9 shows the overall configuration of the laser processing apparatus according to the second embodiment. This apparatus is mainly suitable for use in welding copper or gold, and includes a YAG fundamental pulse laser beam having a fundamental wavelength (1064 nm) and a harmonic such as a YAG harmonic pulse laser beam having a second harmonic (532 nm). Is a laser processing apparatus of a type that irradiates the processing point WP of the workpiece W by superimposing. The main part different from the first embodiment described above is provided with two YAG pulse laser oscillators 66 and 68 that oscillate and output the YAG fundamental laser beam LA and the YAG harmonic laser beam SHG, respectively, to the laser processing machine body 64. And an optical system for superimposing the YAG fundamental laser beam LA and the YAG harmonic laser beam SHG in the laser processing head 70 is incorporated.

  Both YAG pulse laser oscillators 66 and 68 and the laser processing head 70 are optically connected by optical fibers 72 and 74, respectively. The laser processing head 70 has a hollow housing or head main body 76 made of, for example, aluminum, and an optical lens, a mirror, etc., which will be described later, are arranged at a predetermined position in the head main body 76. In the head main body 76, a laser emission port 78 is provided on the lower surface of the main body facing the processing point WP of the workpiece W, and the end portions of both optical fibers 72 and 74 are provided on the upper surface of the main body opposite to the laser emission port 78. Optical fiber connection portions 80 and 82 for removably attaching and laser light detectors 84, 86 and 88 for monitoring are attached.

  10 to 12 show a specific configuration of the laser processing head 70. 10 is a top view, FIG. 11 is a longitudinal sectional view taken along line XX in FIG. 10, and FIG. 12 is a longitudinal sectional view taken along line YY in FIG.

  As shown in FIGS. 11 and 12, a cylindrical portion 90 extending downward from the center of the lower surface of the head main body 76 is formed, and a protective glass 92 is attached to the lower end portion of the cylindrical portion 90, that is, the laser emission port 78. A focusing lens 94 is disposed in front of the glass 92.

  A YAG fundamental wave system bent mirror 96 is disposed immediately above the focusing lens 94 at a substantially central position inside the head main body 76 with its reflecting surface 96a facing obliquely downward in the X direction at an angle of 45 °, for example (FIG. 11). ), A YAG harmonic system bent mirror 98 is disposed immediately above it with its reflecting surface 98a inclined downward in the Y direction at an angle of 45 °, for example (FIG. 12), and a reflected light detector 88 is disposed immediately above it. The light receiving surface is arranged vertically downward. Here, the reflected light detector 88 is attached to a sensor attachment opening provided on the upper surface of the head main body 76 (FIGS. 11 and 12). An optical filter (not shown) similar to the optical filter 35 in FIG. 2 may be disposed between the YAG harmonic system bent mirror 98 and the reflected light detector 88. In this case, the optical filter may include a filter that selectively transmits the wavelength of the YAG fundamental wave that is the main laser light.

  On the upper surface of the head main body 76, a cylindrical optical fiber mounting portion 80 extends vertically upward at a position offset in the X direction from the reflected light detector 88 on the head central axis. At the upper end of the optical fiber attachment portion 80, a connector or receptacle 106 for receiving the terminal portion of the optical fiber 72 in a detachable manner is provided.

  As shown in FIG. 11, a collimating lens 108 for making the laser light LB emitted radially from the end surface 72 a of the optical fiber 72 into parallel light is disposed inside the optical fiber mounting portion 80. A bent mirror 110 is arranged directly below the lens 108 with its reflecting surface 110a inclined upward at an angle of 45 ° in the −X direction, for example. Here, the reflecting surface 110 a of the bent mirror 110 is optically opposed to the reflecting surface 96 a of the bent mirror 96, and the YAG fundamental pulse laser light LA from the end surface 72 a of the optical fiber 72 passes through the optical path through the bent mirror 110. The light beam is bent at a right angle from the vertical direction to the horizontal direction (−X direction) and then incident on the vent mirror 96. It is like that. The converging lens 94 condenses the YAG fundamental wave pulse laser beam LA at the processing point WP of the workpiece W.

On the upper surface of the head main body 76, the YAG fundamental wave laser light detector 84 is offset from the reflected light detector 88 to the opposite side (-X direction) from the YAG fundamental wave fiber optic mounting portion 80. The light receiving surface is arranged vertically downward. Here, the laser light detector 84 is attached to a sensor attachment opening provided on the upper surface of the head main body 76. Bent mirror 112 is arranged directly below laser light detector 84 with its reflecting surface 112a facing obliquely upward at an angle of 45 ° in the X direction, for example. The reflecting surface 112 a of the bent mirror 112 is optically opposed to the reflecting surface 110 a of the bent mirror 110 via the vent mirror 96, and the YAG fundamental wave laser light LA from the end surface 72 a of the optical fiber 72 is the bent mirror 96. Light _MLA leaked to the rear (−X direction) of the vent mirror 96 when reflected vertically downward (on the focusing lens 94 side) is incident on the vent mirror 112, and the optical path of the vent mirror 112 is perpendicular to the vertical direction from the horizontal direction. And is incident on the light-receiving surface of the YAG fundamental wave laser beam detector 84. An optical filter (not shown) similar to the optical filter 44 of FIG. 2 may be disposed between the vent mirror 96 and the vent mirror 112.

YAG fundamental wave laser beam detector 84 has a photoelectric conversion element, for example a photodiode, an electric signal representing the light intensity by receiving the leaked light M _LA of the YAG fundamental leaking from the bent mirror 96 in the X direction S Generate _LA . Here, the light intensity of the leaked light M _LA has a certain proportional relationship with the light intensity of the YAG fundamental wave laser light LA immediately after being emitted from the end face 72 a of the optical fiber 72 or the laser output P _LA . Output signal (YAG fundamental wave laser beam intensity detection signal) S _LA of the laser beam detector 84 is sent to the monitor device body 16 via the signal line 114.

  Further, as shown in FIG. 12, a cylindrical optical fiber mounting portion 82 extends vertically upward on the upper surface of the head body 76 at a position offset in the Y direction from the reflected light detector 88 on the head central axis. ing. A connector or receptacle 118 that detachably receives the terminal end of the optical fiber 74 is provided at the upper end of the optical fiber attachment portion 82.

  A collimating lens 120 for making the YAG harmonic pulse laser beam SHG emitted radially from the end surface 74 a of the optical fiber 74 into parallel light is disposed inside the optical fiber mounting portion 82. Bent mirror 122 is arranged directly below the reflecting surface 122a at an angle of, for example, 45 ° in the Y direction. Here, the reflecting surface 122 a of the vent mirror 122 is optically opposed to the reflecting surface 98 a of the vent mirror 98, and the YAG harmonic pulse laser light SHG from the end surface 74 a of the optical fiber 74 passes through the optical path by the vent mirror 122. The light beam is bent at a right angle from the vertical direction to the horizontal direction (−Y direction) and then incident on the vent mirror 98. The light enters the focusing lens 94. The converging lens 94 focuses the YAG harmonic pulse laser beam SHG on the processing point WP of the workpiece W.

In FIG. 12, on the upper surface of the head main body 76, YAG harmonic laser light detection is performed at a position offset from the reflected light detector 88 on the opposite side (−Y direction) from the YAG harmonic optical fiber mounting portion 82. A device 86 is arranged with its light receiving surface facing vertically downward. Here, the laser light detector 86 is attached to a sensor attachment opening provided on the upper surface of the head main body 76. Bent mirror 124 is arranged directly below laser light detector 86 with its reflecting surface 124a facing obliquely upward at an angle of 45 ° in the Y direction, for example. Here, the reflecting surface 124a of the vent mirror 124 is optically opposed to the reflecting surface 122a of the vent mirror 122 via the vent mirror 98, and the YAG harmonic laser beam SHG from the end surface 74a of the optical fiber 74 is vented. The light M _SHG leaked to the rear (−Y direction) of the vent mirror 98 when reflected by the mirror 98 vertically downward (on the focusing lens 94 side) is incident on the vent mirror 124, and the optical path is changed in the horizontal direction (− The YAG harmonic laser beam detector 86 is incident on the light receiving surface of the YAG harmonic laser beam detector 86 by bending it vertically upward from the Y direction. An optical filter (not shown) similar to the optical filter 44 of FIG. 2 may be disposed between the vent mirror 98 and the vent mirror 124.

The YAG harmonic laser light detector 86 has a photoelectric conversion element such as a photodiode, and receives YAG harmonic leaked light M _SHG leaking rearward (−Y direction) from the vent mirror 96, and the light intensity thereof is _measured. An electrical signal S _SHG is generated. Here, the light intensity of the leaked light M _SHG is in a certain proportional relationship with the light intensity of the YAG harmonic laser light SHG immediately after being emitted from the end face 74 a of the optical fiber 74 or the laser output P _SHG . The output signal (YAG harmonic laser beam intensity detection signal) S _SHG of the laser beam detector 86 is sent to the monitor device main body 16 via the signal line 126.

The reflected light detector 88 has a photoelectric conversion element, for example a photodiode, an electric signal representing the light intensity by receiving the reflected light R _LA coming exit from the optical lens 94 a bent mirror 96, 98 vertically upwards S _{R ′} is generated. Here, the light intensity of the reflected light R depends on the surface reflectance at the machining point WP of the workpiece W, the degree of penetration, etc., but at least has a certain proportional relationship with the laser output (particularly the YAG fundamental wave) at the machining point WP. It is in. The output signal (reflected light intensity detection signal) S _{R ′} of the reflected light detector 88 is sent to the monitor device main body 16 via the signal line 128.

The monitor device main body 16 includes a YAG fundamental wave laser beam intensity detection signal S _LA sent from the three photodetectors 84, 86, and 88 attached to the laser processing head 70 via signal lines 114, 126, and 128. Based on the YAG harmonic laser light intensity detection signal S _SHG and the reflected light intensity detection signal S _{R ′} , the state of the optical components through which the YAG fundamental laser beam LA and the YAG harmonic laser beam SHG pass, the state of the workpiece W, and the laser output state Optical measurement and pass / fail judgment can be performed in-line.

  Also in this embodiment, the same effect as the first embodiment described above can be obtained. In particular, in the laser processing head 70, all of the optical fibers 72 and 74, the YAG fundamental wave laser light detector 84, the YAG harmonic laser light detector 86, and the reflected light detector 88 are connected to or attached to the upper surface of the head. The optical fibers 72 and 74 and the signal lines 114, 126, and 128 can be aggregated above the head and laid over or laid, so that the space efficiency, ease of use, maintenance, and safety are further increased. There are advantages.

In the above-described embodiment, the laser beam measurement unit 26 (84, 86) and the reflected light measurement unit 28 (88) attached to the upper surface of the laser processing head 12 (70) are configured by photoelectric conversion elements, and these photoelectric conversion elements. The electric signals S _L (S _LA , S _SHG ), SR (S _{R ′} ) output from the signal line 46 (114, 126), 48 (128) are sent to the monitor device main body 16 via the signal lines 46 (114, 126), 48 (128). However, for example, as shown in FIG. 13, in the laser processing head 12, the laser light measurement unit 26 and / or the reflected light measurement unit 28 can be configured by optical fibers 130 and 132.

More specifically, one end of the optical fiber 130 is attached to the attachment position of the laser light detector 26 (FIG. 2), and the leaked light M _LB of the laser light LB reflected vertically upward from the vent mirror 42 is one of the optical fibers 130. The light is incident on the end surface (light receiving surface) 130a. One end of the optical fiber 132 is attached to the attachment position of the reflected light detector 28 (FIG. 2), and the leaked light R _LB of the reflected light transmitted vertically upward from the vent mirror 34 is one end surface (light receiving surface) of the optical fiber 132. ) So that it is incident on 132a. The other end portions (terminal portions) of both optical fibers 130 and 132 are connected to a monitor device main body (not shown), and the laser leakage light M _LB emitted from the other end surfaces of both optical fibers 130 and 132 on the monitor device main body side. The reflected leakage light R _LB is converted into electrical signals S _L and S _R by photoelectric conversion elements (not shown), respectively.

  Also in this configuration example, the same effect as that of the first embodiment described above can be obtained. In particular, in the laser processing head 12, all of the optical fibers 14, 130, and 132 can be aggregated over the head and laid overhead, which is a further advantage in terms of space efficiency, ease of use, maintainability, and safety.

It is a figure which shows the whole structure of the laser processing apparatus in one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the specific structure of the laser processing head in embodiment. It is a block diagram which shows the functional structure of the signal processing part in the monitor apparatus main body in the laser processing apparatus of embodiment. It is a wave form diagram which shows the waveform of the pulse laser beam in each part of the monitoring apparatus for laser processing of embodiment. It is a figure which shows the monitoring area with respect to a single pulse laser beam, a calculation area, and the light intensity measurement calculation method (an example) in embodiment. It is a figure which shows the monitoring area with respect to a single pulse laser beam, a calculation area, and the light intensity measurement calculation method (an example) in embodiment. It is a figure which shows the monitoring section with respect to a series (a plurality of shots) pulsed laser beam, a calculation section, and the light intensity measurement calculation method (an example) in the embodiment. It is a figure which shows the monitoring section with respect to a series (a plurality of shots) pulsed laser beam, a calculation section, and the light intensity measurement calculation method (an example) in the embodiment. It is a figure which shows the whole structure of the laser processing apparatus in another embodiment. It is a top view which shows the structure of the ray processing head in another embodiment. It is a longitudinal cross-sectional view about the XX line of FIG. It is a longitudinal cross-sectional view about the YY line of FIG. It is a longitudinal cross-sectional view which shows the structure of the laser processing head in another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser processing machine main body 10a Laser oscillator 12 Laser processing head 14 Optical fiber 16 Monitor apparatus main body 18 Controller 20 Head main body 22 Laser emission port 24 Optical fiber attachment part 26 Laser light detector 28 Reflected light receiver 30 Protective glass 32 Focusing lens 34 , 40, 42 Vent mirror 38 Collimator lens 46, 48 Signal line 66 YAG fundamental laser oscillator 68 YAG harmonic laser oscillator 70 Laser processing head 76 Head body 78 Laser exit port 80, 82 Optical fiber mounting portion 84 Laser light detector 86 Reflected light receiver 96, 98, 110, 112 Vent mirror 104, 116
108,120 Collimating lens

Claims (6)

The laser beam oscillated and output from the laser oscillation unit is transmitted to a laser processing head via an optical fiber for laser transmission, and the laser beam is focused and irradiated from the laser processing head toward the workpiece. A laser processing apparatus for processing,
A laser emission port on the first surface facing the processing point of the workpiece, and an optical fiber connection portion for attaching the end portion of the optical fiber to the second surface opposite to the first surface, respectively. A head main body for accommodating an optical lens for condensing the laser light emitted from the end face of the optical fiber at a processing point of the workpiece, and attaching a protective glass to the laser emission port;
A laser output measuring unit for measuring the output of the laser light before entering the optical fiber;
A laser beam measurement unit attached to the head body for measuring the light intensity of the laser beam emitted from the end face of the optical fiber;
A reflected light measurement unit attached to the head body to measure the light intensity of light reflected from the processing point of the workpiece into the laser emission port;
Based on the measured value of the laser beam output obtained from the laser output unit and the measured value of the laser beam intensity obtained from the laser beam measuring unit, it is monitored whether or not the optical fiber is normal. A first monitor unit that
Based on the measurement value of the light intensity of the laser light obtained from the laser light measurement unit and the measurement value of the light intensity of the reflected light obtained from the reflected light measurement unit, the surface state of the workpiece is normal. A second monitor unit for monitoring whether or not the protective lens is abnormally soiled;
A laser processing apparatus. The laser beam is a pulsed laser beam,
The reflected light measurement unit sets a calculation interval from a first time after a predetermined time after the rising edge of the pulsed laser light to a second time before a falling time of the pulsed laser light as the calculation interval. The average value, integrated value, maximum value, or peak value of the light intensity of the reflected light determined in the measurement value,
The laser processing apparatus according to claim 1. The second monitor unit calculates a ratio of the light intensity measurement value of the reflected light to the light intensity measurement value of the laser light, and monitors how the ratio decreases with time. 2. The laser processing apparatus according to 2. The laser processing apparatus according to claim 1, wherein the laser light measurement unit is attached to a second surface of the head main body . A second mirror provided in said head body light leaking to the back side of the first mirror corresponding to the laser beam to reflect toward the laser light measurement unit, according to claim 4 Laser processing equipment. The reflected light measuring unit is attached to the second surface of the head body, the laser processing apparatus according to any one of claims 1-5.

Images