JP2012024808A - Scanning type laser beam machining apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the consistent function of a galvano mirror by simply monitoring the temperature of a mirror holder of a galvano scanner to reliably prevent any excessive temperature rise.SOLUTION: A temperature monitoring unit in a laser beam machining apparatus has a bar-shaped or probe-shaped X-axis thermal interlocking unit 90and Y-axis thermal interlocking unit 90which are arranged in a scanner casing 60 close to an X-axis mirror holder 78and a Y-axis mirror holder 78, respectively, so as not to interfere in their rotating (oscillating) motions. The X-axis thermal interlocking unit 90(the Y-axis thermal interlocking unit 90) accommodates a thermal switch as a temperature-sensing element deeply inside a cylindrical casing to electrically connect the internal thermal switch to an external control circuit via an electric cable 96(96).

Description

  The present invention relates to a scanning laser processing apparatus that performs desired laser processing by irradiating a workpiece with laser light using a galvano scanner.

  In scanning laser processing, a laser beam is irradiated on the surface of the work piece while momentarily evaporating, discoloring, or melting a minute portion (work point) of the work piece surface to which the laser beam spot hits. This is a processing technique that scans (scans) a spot in a desired pattern. Marking is typical, but it is also used for seam welding (see Patent Documents 1 and 2).

  In general, a scanning laser processing apparatus includes a laser oscillator that oscillates and outputs laser light, a galvano scanner that irradiates a workpiece while scanning the laser light output from the laser oscillator, and a laser oscillator and a galvano scanner. And a control unit for controlling each operation (laser oscillation operation, scanning operation).

  In the past, a Q-switch pulse YAG laser has been frequently used for marking processing, and a long pulse or continuous (CW) oscillation YAG laser has been frequently used for seam welding. Recently, YAG lasers are being replaced by higher power fiber lasers.

  The galvano scanner is also called a scanning head or the like, and an X-axis galvano mirror and a Y-axis galvano mirror for two-dimensionally scanning laser light are arranged in a box-shaped scanner housing, and a desired scanning is performed by a control unit. In response to the coordinate position command signal or the mirror deflection angle command signal corresponding to the position, each galvanometer mirror is driven to rotate (swing) by an electric rotation drive unit. A laser emission port for emitting laser light to the outside is formed on one wall surface (usually the bottom wall) of the scanner housing, and laser light scanned by an X-axis galvanometer mirror and a Y-axis galvanometer mirror is formed in this window. An optical lens (fθ lens) for condensing the light at a processing point of the workpiece is attached.

JP2002-210573 JP2007-12752

  In the scanning laser processing apparatus as described above, the X-axis galvanometer mirror and the Y-axis galvanometer mirror of the galvano scanner are respectively coupled to the rotation axes of the X-axis rotation drive unit and the Y-axis rotation drive unit via individual mirror holders. Has been. In general, the X-axis galvanometer mirror, the Y-axis galvanometer mirror, and each individual mirror holder are coupled by an adhesive.

  However, when a galvano scanner is used to irradiate the workpiece with laser light, part of the light reflected by the workpiece returns into the scanner housing and strikes the mirror holder, thereby absorbing the reflected light (that is, absorbing the reflected light). E) The temperature of the mirror holder rises. Depending on the power of the reflected light and the irradiation duration, the temperature of the mirror holder may exceed the heat resistance temperature (usually about 60 ° C. to 80 ° C.) of the adhesive fixing the galvanometer mirror to the mirror holder. When this happens, the adhesive softens and the galvanometer mirror wobbles, thereby reducing the accuracy of the deflection angle of the galvanometer mirror and thus the scanning accuracy of the laser beam.

  In particular, when seam welding is performed by irradiating a workpiece made of a material having high reflectivity (for example, aluminum) with laser light to be used by continuous (CW) oscillation laser light, reflection from the workpiece is performed. Since a large amount of light continuously enters the scanner housing, the mirror holder tends to be over-heated as described above and the galvanometer mirror is wobbled due to the softening of the adhesive. Further, when the temperature rises due to the heat generated by the mirror holder or the like, the reflectance of the galvano mirror may change, and the laser beam may not be scanned accurately.

  The present invention solves the problems of the prior art as described above, and when the reflected light from the workpiece hits the mirror holder that holds and holds the galvanometer mirror, the temperature of the mirror holder is simply monitored. The present invention provides a scanning laser processing apparatus that reliably prevents overheating and maintains the function of a galvano mirror stably.

  A scanning laser processing apparatus according to a first aspect of the present invention is a scanning laser processing apparatus that scans a processing point of a workpiece with a laser beam and processes the workpiece with the energy of the laser beam. A laser oscillation unit that oscillates and outputs the laser beam; a galvano mirror that reflects the laser beam from the laser oscillation unit toward the processing point; a mirror holder that holds the galvano mirror; and the mirror holder A galvano scanner having a galvano mirror coupled to the mirror holder with an adhesive, and at least the galvano mirror and the mirror of the galvano scanner. Covering and accommodating the holder, and having a laser emission window for emitting the laser beam to the outside A temperature sensor disposed within the scanner housing, and when the temperature of the temperature sensor exceeds a predetermined monitoring temperature, a predetermined interlock signal is output based on the output of the temperature sensor. A temperature monitoring unit that generates, and a control unit that stops oscillation output of the laser light in the laser oscillation unit in response to the interlock signal generated by the temperature monitoring unit.

  In the laser processing apparatus having the above configuration, during laser processing, most of the light reflected by the workpiece irradiated with the laser light propagates in the opposite direction to the laser light and enters the scanner housing, and part of it. Hits the mirror holder. The mirror holder rises in temperature when exposed to reflected light. In the present invention, when the reflected light from such a workpiece is absorbed and the temperature of the mirror holder is likely to exceed the predetermined monitoring temperature, or when it exceeds, the temperature monitoring unit Generates an interlock signal, and in response to this, the control unit stops the laser oscillation output. As a result, the galvanometer mirror does not wobble due to the softening of the adhesive that holds and holds the mirror mirror in the mirror holder.

  A scanning type laser processing apparatus according to a second aspect of the present invention is a scanning type laser processing apparatus that performs a desired laser processing by irradiating a processing point of a workpiece with a laser beam. A laser oscillation unit that oscillates and outputs; a first galvanomirror that reflects the laser light from the laser oscillation unit toward a second galvanometer mirror; and a first mirror holder that holds the first galvanometer mirror; A first rotation driving unit that rotationally drives the first galvanometer mirror in a first direction via the first mirror holder, and the first galvanometer mirror is used as the first mirror holder. A first galvano scanner coupled using an adhesive, and the second galvano that reflects the laser light from the first galvano scanner toward the processing point. And a second mirror holder that holds the second galvanometer mirror, and the second galvanometer mirror is driven to rotate in a second direction orthogonal to the first direction via the second mirror holder. And a second galvano scanner for bonding the second galvanometer mirror to the second mirror holder using an adhesive, and the first and second galvanometers. A scanner housing which covers and accommodates at least the first and second galvanometer mirrors and the first and second mirror holders of a scanner and has a laser emission port for emitting the laser beam to the outside; and the scanner A first and a second temperature sensing element disposed in a position relatively close to the first mirror holder and the second mirror holder in the housing, respectively, and the temperature of the first temperature sensing element; Based on the output of the first temperature sensing element or the second temperature sensing element when the first monitoring temperature is exceeded or when the temperature of the second temperature sensing element exceeds the second monitoring temperature. A temperature monitoring unit that generates an interlock signal; and a control unit that stops the oscillation output of the laser light in the laser oscillation unit in response to the interlock signal generated by the temperature monitoring unit.

  In the second aspect, since the first and second temperature sensitive elements respectively disposed at positions relatively close to the first mirror holder and the second mirror holder operate independently, In addition to the same effect as the first aspect, a more reliable interlock mechanism can be obtained by the double interlock generation source (temperature sensing element).

  In a preferred aspect of the present invention, the first mirror holder is disposed at a position where the first mirror holder directly receives a part of light entering the scanner housing from the workpiece through the laser emission port. The temperature sensitive element is arranged at a position where a part of the light entering the scanner casing from the workpiece through the laser emission port is directly exposed. Further, the second mirror holder is disposed at a position where the second mirror holder is directly exposed to a part of light entering the scanner casing from the workpiece through the laser emission port, and the second temperature sensing element is disposed on the workpiece. It is arranged at a position where a part of light entering the scanner casing through the laser emission port from the workpiece is directly exposed.

  In another preferred embodiment, the temperature monitoring unit covers the temperature sensitive element with a casing made of a material having a light absorption rate higher than that of the mirror holder with respect to light from the workpiece. Preferably, the mirror holder is made of aluminum and the casing is made of stainless steel.

  In a preferred embodiment, the temperature sensitive element comprises a thermal switch that turns on or off the contact of the electric circuit when the temperature reaches a preset temperature. In this case, when the temperature of the mirror holder exceeds the monitoring temperature, the thermal switch is turned on or off to generate an interlock signal.

  In another preferred embodiment, the temperature sensitive element is a temperature sensor that generates an electric signal having a magnitude corresponding to the ambient temperature. In this case, the temperature monitoring unit includes an interlock signal generation circuit that compares the electrical signal from the temperature sensor with a predetermined reference value and outputs an interlock signal when the electrical signal exceeds the reference value.

  According to the scanning type laser processing apparatus of the present invention, when the reflected light from the workpiece hits the mirror holder that holds and holds the galvano mirror through the adhesive, the mirror holder of the mirror holder is applied by the above configuration and operation. The temperature can be easily monitored to reliably prevent overheating, and the function of the galvanometer mirror can be kept stable. As a result, the scanning accuracy and reliability of the laser beam can be stably maintained.

It is a figure which shows the structure of the laser processing apparatus of the scanning system in one Embodiment of this invention. It is a side view which shows the structure inside and outside the scanner housing | casing in the laser processing apparatus of embodiment. It is a bottom view which shows the structure inside and outside the scanner housing | casing in the laser processing apparatus of embodiment. It is a perspective view which shows the structure around the mirror holder in the laser processing apparatus of embodiment. It is a top view which shows the positional relationship of the mirror holder and thermal interlock part in the laser processing apparatus of embodiment. It is a top view which shows the positional relationship of the mirror holder and thermal interlock part in the laser processing apparatus of embodiment. It is a perspective view which shows the external appearance structure of the thermal interlock part in the laser processing apparatus of embodiment. It is sectional drawing which shows the internal structure of the thermal interlock part in the laser processing apparatus of embodiment. It is the figure which overlapped and showed the position of the laser irradiation pattern (test pattern 1) in one experiment of embodiment on the laser emission port of a scanner housing | casing. It is a waveform diagram of the temperature of each part obtained in the test pattern 1 experiment. It is the figure which showed the position of the laser irradiation pattern (test pattern 2) in one experiment of embodiment overlaid on the laser emission port of the scanner housing. It is a waveform diagram of the temperature of each part obtained in the test pattern 2 experiment. It is the figure which overlapped and showed the position of the laser irradiation pattern (test pattern 3) in one experiment of embodiment on the laser emission port of a scanner housing | casing. It is a waveform diagram of the temperature of each part obtained in the test pattern 3 experiment. It is the figure which overlapped and showed the position of the laser irradiation pattern (test pattern 4) in one experiment of embodiment on the laser emission port of a scanner housing | casing. It is a waveform diagram of the temperature of each part obtained in the test pattern 4 experiment. It is the figure which showed the position of the laser irradiation pattern (test pattern 5) in one experiment of embodiment overlaid on the laser emission port of the scanner housing. It is a waveform diagram of the temperature of each part obtained in the test pattern 5 experiment. It is the figure which showed the position of the laser irradiation pattern (test pattern 6) in one experiment of embodiment overlaid on the laser emission port of the scanner housing. It is a waveform diagram of the temperature of each part obtained by the test pattern 6 experiment. It is the figure which showed the position of the laser irradiation pattern (test pattern 7) in one experiment of embodiment overlaid on the laser emission port of the scanner housing. It is a waveform diagram of the temperature of each part obtained by the experiment of the test pattern 7. It is the figure which overlapped and showed the position of the laser irradiation pattern (test pattern 8) in one experiment of embodiment on the laser emission port of a scanner housing. FIG. 6 is a waveform diagram of the temperature of each part obtained in the test pattern 8 experiment.

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

  FIG. 1 shows the configuration of a scanning laser processing apparatus according to an embodiment of the present invention. This laser processing apparatus is a laser processing machine applicable to laser processing using a galvano scanner, for example, seam welding, and includes a fiber laser oscillator 10, a laser power source 12, a laser transmission system 14, a laser emitting unit 16, a main control unit 18, a touch panel. 20 is provided.

  The fiber laser oscillator 10 includes an oscillation optical fiber (hereinafter referred to as “oscillation fiber”) 22, an electro-optical excitation unit 24 that irradiates one end surface of the oscillation fiber 22 with pumping excitation light MB, and an oscillation fiber. And a pair of optical resonator mirrors 26 and 28 that are optically opposed to each other via 22, and an electro-optic conversion unit that converts electrical energy supplied from the laser power source 12 into laser energy of laser light in the entire oscillator. Is configured.

The electro-optic excitation unit 24 includes a laser diode (LD) 30 as an excitation light source and a condensing optical lens 32. When the seam welding is performed by the continuous (CW) oscillation laser beam FB, the LD 30 is supplied or injected with the LD drive current _ID of CW having a desired current value from the laser power source 12, and the CW excitation light (LD Light) MB is generated. The optical lens 32 condenses and enters the excitation light MB from the LD 30 onto one end surface of the oscillation fiber 22. The optical resonator mirror 26 disposed between the LD 30 and the optical lens 32 transmits the excitation light MB incident from the LD 30 side, and totally reflects the oscillation light incident from the oscillation fiber 22 side on the optical axis of the resonator. Is configured to do.

  Although not shown, the oscillation fiber 22 has a core doped with, for example, rare earth element ions as a light emitting element, and a clad surrounding the core coaxially. The core is used as an active medium, and the clad is used as the propagation of excitation light. The light path. The pulse excitation light MB incident on one end face of the oscillation fiber 22 as described above propagates in the oscillation fiber 22 in the axial direction while being confined by total reflection at the cladding outer peripheral interface. Across the core, photoexcites rare earth ions in the core. In this way, an oscillating light beam having a predetermined wavelength is emitted in the axial direction from both end faces of the core, and this oscillating light beam travels back and forth between the optical resonator mirrors 26 and 28 and is resonantly amplified. The CW laser beam FB having the predetermined wavelength is extracted from the optical resonator mirror 28.

  In the optical resonator, the optical lenses 32 and 34 collimate the oscillating light beam emitted from the end face of the oscillating fiber 22 into parallel light and pass it to the optical resonator mirrors 26 and 28. The oscillation light beam reflected and returned by 28 is condensed on the end face of the oscillation fiber 22. The excitation light MB that has passed through the oscillating fiber 22 passes through the optical lens 34 and the optical resonator mirror 28 and is then folded back toward the side laser absorber 38 by the folding mirror 36. The CW laser beam FB output from the optical resonator mirror 28 passes straight through the folding mirror 36, and then passes out of the fiber splitter 10 through the beam splitter 40.

The beam splitter 40 reflects a small portion (for example, 1%) of the incident laser beam FB in a predetermined direction, that is, the power monitor photosensor (PD) 42 side, and transmits the remaining most (99%) straightly. . A condensing lens 44 that condenses the reflected light from the beam splitter 40 or the monitor light R _FB is disposed in front of the photo sensor (PD) 42.

The photosensor (PD) 42 photoelectrically converts the monitor light R _FB from the beam splitter 40 and outputs an electrical signal (laser output measurement signal) representing the laser output (power) of the laser light FB. The laser output measurement circuit 46 obtains the laser output measurement value M _FB of the laser beam FB by analog signal processing based on the output signal of the photosensor 42. The laser output measurement value M _FB obtained by the laser output measurement circuit 46 is given to the laser power source 12 as a feedback signal.

  The laser beam FB that passes straight through the beam splitter 40 and exits the fiber laser oscillator 10 enters the laser transmission system 14, is first turned back in a predetermined direction by the vent mirror 48, and then is condensed in the incident unit 50. The light is condensed by 52 and is incident on one end surface of a transmission optical fiber (hereinafter referred to as “transmission fiber”) 54. The transmission optical fiber 52 is made of, for example, an SI (step index) type fiber, and transmits the laser light FB incident in the incident unit 50 to the laser emitting unit 16.

The laser emitting unit 16 includes an X-axis galvano scanner 56 _X and a Y-axis galvano scanner 56 _{Y, which} will be described later with reference to FIGS. And a scanner control unit 62 for individually controlling the rotation (swinging) operation of the X-axis galvano scanner 56 _X and the Y-axis galvano scanner 56 _Y in accordance with the scanning control signal.

On one side wall of the scanner housing 60, a laser introduction port 60a to which an end of the transmission optical fiber 52 is attached is provided, and a collimator lens 64 is disposed in the vicinity thereof. The laser beam FB emitted from the exit end of the transmission optical fiber 52 at a predetermined divergence angle is collimated by the collimator lens 64 and sequentially enters the galvano scanners 56 _X and 56 _Y.

  Further, a laser emission port 60b for emitting the laser beam FB to the outside is provided on the bottom wall of the scanner housing 60. An fθ lens 65 for condensing the laser beam FB at a processing point of the workpiece W on the processing stage 66 is attached to the laser emission port 60b.

  On the workpiece W, machining points are continuously set in a line shape as a desired seam welding line. At each processing point where the beam spot of the laser beam FB is condensed and irradiated, the workpiece W is melted by the laser energy, and solidifies after the beam spot leaves to form a nugget.

  The main control unit 18 includes a CPU (microcomputer), and controls the operation of the entire apparatus or each unit according to various programs (software) stored in the program memory, and the input unit 20a and the display unit 20b of the touch panel 20 are controlled. And exchanges information (setting values, monitor information, etc.) with users (operators, maintenance personnel, etc.).

  2 and 3 show the main part of the laser emitting section 16 in this embodiment. 2 is a side view seen from the laser introduction port 60a side, and FIG. 3 is a bottom view seen from the laser emission port 60b side.

As shown in FIG. 2, the X-axis galvanometer mirror 70 _X of the X-axis galvano scanner 56 _X faces the laser introduction port 60a on the side wall of the scanner housing 60 in an inclined posture of about 45 °. The laser beam FB emitted from the exit end of the transmission optical fiber 52 is incident on the X-axis galvanometer mirror 70 _X immediately after passing through the collimator lens 64. The rotation drive unit 72 _X of the X-axis galvano scanner 56 _X is housed in a cylindrical X-axis galvano casing 74 _X that protrudes outside the scanner housing 60 and extends through the electric cable 76 _X. 62 (FIG. 1).

On the other hand, as shown in FIG. 3, the Y-axis galvano mirror 70 _Y of the Y-axis galvano scanner 56 _Y faces the laser emission port 60b on the bottom wall of the scanner housing 60 in an inclined posture of about 45 °. Among the scanner housing 60 faces obliquely at an angle X-axis galvanometer mirror 70 _X and Y-axis galvanometer mirror 70 _Y together also predetermined cross each other. The rotation drive unit 72 _Y of the Y-axis galvano scanner 56 _Y is housed in a cylindrical Y-axis galvano casing 74 _Y that protrudes outside the scanner housing 60 and extends through the electric cable 76 _Y. 62 (FIG. 1).

As shown in FIGS. 2 and 4, in the X-axis galvano scanner 56 _X , the X-axis galvanometer mirror 70 _X has a base end tapered (tapered) and has a longitudinal section U shape at the edge. It is coupled to the rotating shaft 80 _X of the rotation drive unit 72 _X via the X-axis mirror holder 78 _X. Here, the X-axis mirror holder 78 _X is integrally coupled to the rotary shaft 80 _X , and the X-axis galvano mirror 70 _X is coupled to the mirror holding groove of the X-axis mirror holder 78 _X via an adhesive. The rotary shaft 80 _X is rotatably held by a clamp member 82 _X.

  A groove extending in the lateral direction is formed on the U-shaped inner surface of the X-axis mirror holder 78x and on the adhesive surface with the X-axis galvanometer mirror 70x. This groove is designed to allow excess adhesive to flow in when the X-axis galvanometer mirror 70x is bonded with an adhesive. Thereby, since excess adhesive agent does not leak out of the adhesive surface, it is possible to prevent a problem that the adhesive agent burns by reflected light.

A stopper pin 84 _X penetrating in one horizontal direction is attached to the rotary shaft 80 _X. As shown in FIGS. 5A and 5B, when the X-axis galvanometer mirror 70 _X is greatly swung, the stopper pin 84 _X hits the side surfaces 86 _L and 86 _R of the fan-shaped protrusion 86 _X adjacent to the rotation shaft 80 _X , and more It cannot be rotated. Thus, a physical upper limit is provided for the rotation angle (swing angle) of the X-axis galvanometer mirror 70 _X.

As shown in FIGS. 3 and 4, also in the Y-axis galvano scanner 56 _Y , the holding structure of the Y-axis galvano mirror 70 _Y is the same as the holding structure of the X-axis galvano mirror 70 _X described above. That, Y-axis galvanometer mirror 70 _Y has its base end portion is formed in a tapered (tapered), the rotation of the edge portion in longitudinal section U-shaped in the Y-axis mirror holder 78 via a _Y rotation driving unit 72 _Y It is coupled to the shaft 80 _Y. Here, the Y-axis mirror holder 78 _Y is integrally coupled to the rotary shaft 80 _Y , and the Y-axis galvanometer mirror 70 _Y is coupled to the mirror holding groove of the Y-axis mirror holder 78 _Y via an adhesive. The rotary shaft 80 _Y is rotatably held by a clamp member 82 _Y. The Y-axis galvanometer mirror 70 _Y is also provided with the same swing stopper structure (84 _Y , 86 _Y ) as described above.

The material of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y is preferably lightweight and excellent in workability, and has a low absorptance with respect to laser light, and usually aluminum is used. Further, highly reflective plating (for example, gold plating) can be applied to the surfaces of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y. By so doing, absorption of the laser beam can be suppressed, and an excessive temperature rise of the mirror holder can be prevented. Further, the temperature rise can be suppressed by blowing air to the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y.

As shown in FIGS. 3 to 5, the temperature monitoring unit 58 in this embodiment is arranged so as to rotate (swing the head) close to the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y in the scanner housing 60. ) A rod-shaped or probe-type X-axis thermal interlock portion 90 _X and a Y-axis thermal interlock portion 90 _Y are provided so as not to interfere with the movement.

As shown in FIGS. 6A and 6B, the X-axis thermal interlock portion 90 _X (Y-axis thermal interlock portion 90 _Y ) is a thermal switch as a temperature sensitive element located inside the cylindrical casing 92 _X (92 _Y ). 94 _X (94 _Y ) is accommodated, and an internal thermal switch 94 _X (94 _Y ) and an external control circuit (main control unit 18) are electrically connected via an electric cable 96 _X (96 _Y ). Yes.

The material of the casing 92 _X (92 _Y ) is preferably higher in light absorption than the material (aluminum) of the mirror holder 78 _X (78 _Y ) with respect to the laser beam FB. In this embodiment, stainless steel SUS304 is used. Used. The casing 92 _X (92 _Y ) preferably has a shape that covers the thermal switch 94 _X (94 _Y ) with almost no gap, and the covering wall is preferably as thin as 1 mm.

The proximal end of the casing 92 _X (92 _Y), the flange 100 _X marked with a bolt hole _{98 X (98 Y) (100} Y) are formed integrally, the flange 100 _X (100 _Y) scanner housing It is fixed to the outer wall of the body 60 with bolts.

In the X-axis thermal interlock section 90 _X (Y-axis thermal interlock section 90 _Y ), the thermal switch 94 _X (94 _Y ) has a switch function that turns on and off according to the ambient temperature, and is set in advance. It is configured to maintain an on (closed) state below the operating temperature and to an off (open) state when the operating temperature is exceeded.

Here, the operating temperature of the thermal switch 94 _X in the X-axis thermal interlock portion 90 _X is usually relative to the X-axis mirror holder 78 _{X in} relation to the heat resistance temperature of the adhesive that fixes and holds the X-axis galvanometer mirror 70 _X. It corresponds to the monitoring temperature set. On the other hand, the operating temperature of the thermal switch 94 _Y in the Y-axis thermal interlock unit 90 _Y is typically the Y-axis mirror holder 78 _Y in relation to the guaranteed temperature of the adhesive material for fixing and holding the Y-axis galvanometer mirror 70 _Y Corresponds to the set monitoring temperature.

Of course, the operating temperature of the thermal switch 94 _X on the X axis side may correspond not only to the monitoring temperature of the X axis mirror holder 78 _X but also to the monitoring temperature of the Y axis mirror holder 78 _Y. Alternatively, the operating temperature of the thermal switch 94 _Y on the Y-axis side may correspond to the monitoring temperature of the X-axis mirror holder 78 _{X as well as} the monitoring temperature of the Y-axis mirror holder 78 _Y.

The main control unit 18 can determine the on (closed) / off (open) state of the thermal switch 94 _X (94 _Y ) via the electric cable 96 _X (96 _Y ). When the thermal switch 94 _X (94 _Y ) is turned off in one or both of the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y , the switch output is received as an interlock signal, The laser oscillation operation of the fiber laser oscillator 10 is immediately stopped through the laser power source 12. Further, when such an interlock is applied, the scanning operation of both the galvano scanners 56 _X and 56 _Y is also stopped through the scanner control unit 62.

As described above, the laser processing apparatus according to this embodiment includes the X-axis mirror holder 78 _X and the Y-axis mirror for fixing and holding the scanning X-axis galvano mirror 70 _X and the Y-axis galvano mirror 70 _Y using an adhesive. A temperature monitoring unit 58 for monitoring the temperature of the holder 78 _Y is provided. The temperature monitoring unit 58 includes probe-type X-axis thermal interlock units 90 _X and Y-axis thermal interlock units in positions close to the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y in the scanner housing 60. 90 _Y is arranged. When either the temperature of the X-axis mirror holder 78 _X or the temperature of the Y-axis mirror holder 78 _Y exceeds a predetermined monitoring temperature due to the heat of reflected light entering the scanner housing 60 from the workpiece W At the same time or before and after that, the temperature sensing element in the X-axis thermal interlock unit 90 _X or the Y-axis thermal interlock unit 90 _Y , that is, the thermal switch 94 _X (94 _Y ) is switched to generate an interlock signal. In response to this, the main controller 18 stops the fiber laser oscillator 10 through the laser power source 12.

Therefore, in seam welding, for example, when the workpiece W is an aluminum material, strong reflected light from the workpiece W enters the scanner housing 60 continuously for a long time, and the X-axis mirror holder 78. _X and Y-axis mirror holder 78 _Y becomes hot, and even if one of the temperatures exceeds the monitored value, the above-described interlock function immediately operates to stop the emission of the laser beam FB. _{In X} (Y-axis mirror holder 78 _Y ), the X-axis galvano mirror 70 _X (Y-axis galvano mirror 70 _Y ) does not wobble due to the softening of the adhesive.

The inventor conducted an experiment to change the scanning position of the laser irradiation pattern with respect to the workpiece W in eight ways in the laser processing apparatus of this embodiment, and the temperature of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y. And the temperature of the X-axis thermal interlock portion 90 _X and the temperature of the Y-axis thermal interlock portion 90 _Y were examined.

  In this experiment, a 94 mm × 94 mm square area AR is set on the surface of an aluminum plate as a sample, and about 449 W (watts) of CW laser light FB is irradiated into the area AR at a scanning speed of 80 mm / sec. As a pattern, a rectangular irradiation pattern PA of 90 mm × 12 mm was repeatedly drawn (shot) several times. The interlock function was kept off.

  FIGS. 7A to 14A show the positions of the laser irradiation patterns PAn (n = 1... 8) selected as the test patterns so as to overlap the laser emission port 60b of the scanner pair 60, and FIGS. 7B to 14B show the lasers. The waveform of the temperature of each part obtained by the experiment concerning the irradiation pattern PAn is shown.

As can be seen from FIGS. 7A to 14A, all of the X-axis mirror holder 78 _X , the Y-axis mirror holder 78 _Y , the X-axis thermal interlock unit 90 _X, and the Y-axis thermal interlock unit 90 _Y pass through the laser emission port 60b. The light from the workpiece W can be directly bathed. In particular, the X-axis mirror holder 78 _{X not} only exposes the light that has passed through the side of the X-axis galvano mirror 70 _{X in} the axial direction out of the light entering the scanner pair 60 from the laser emission port 60 b to the upper surface of the holder. Then, a part of the light reflected by the Y-axis galvanometer mirror 70 _Y falls on the side of the holder. On the other hand, the Y-axis mirror holder 78 _Y irradiates, on the upper surface of the holder, light that travels straight toward the Y-axis mirror holder 78 _Y out of the light that enters the scanner pair 60 from the laser emission port 60b.

7B to 14B, “X holder” and “Y holder” correspond to the X axis mirror holder 78 _X and Y axis mirror holder 78 _Y , respectively, and “X thermal” and “Y thermal” are X axis thermal interlocks. Respectively corresponding to the portion 90 _X and the Y-axis thermal interlock portion 90 _Y. Each temperature of “X holder”, “Y holder”, “X thermal”, and “Y thermal” was measured using a thermocouple. For example, in FIG. 7B, “22 shots / about 110 seconds” means that the test pattern (laser irradiation pattern) PA ₁ was repeatedly drawn 22 times in about 110 seconds.

[Test pattern 1]

7A and 7B show a case where the laser irradiation pattern PA ₁ is drawn horizontally at the center of the area AR so as to overlap the Y coordinate axis (X = 0). In this case, the temperature of the X-axis mirror holder 78 _X easily exceeded 60 ° C. and rose to a maximum of 71 ° C. On the other hand, the temperature of the X-axis thermal interlock portion 90 _X exceeded 80 ° C. and increased to a maximum of 86.4 ° C. (estimated value). On the other hand, the temperature of the Y-axis mirror holder 78 _Y did not reach 60 ° C. and was a maximum of 33.5 ° C. On the other hand, the temperature of the Y-axis thermal interlock part 90 _Y has easily exceeded 80 ° C. and increased to a maximum of 110 ° C. (estimated value).

Therefore, for example, the monitoring temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both set to 60 ° C., and the operating temperatures of the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y are both set. When set to 80 ° C., when the laser processing of the laser irradiation pattern PA ₁ like this time is executed, the temperature of the X-axis mirror holder 78 _X exceeds the monitoring temperature (60 ° C.), but almost simultaneously with the X-axis thermal. The interlock unit 90 _X performs a switch operation to apply the interlock. However, in this case, the Y-axis thermal interlock unit 90 _Y performs the switching operation before the X-axis thermal interlock unit 90 _X to apply the interlock. When the interlock is applied, laser processing stops at that point.

[Test pattern 2]

8A and 8B show the case where the laser irradiation pattern PA ₂ is drawn horizontally at the bottom of the area AR. In this case, the temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y did not reach 60 ° C., and the maximum temperatures were 38.8 ° C. and 33.2 ° C., respectively. On the other hand, the temperatures of the X-axis thermal interlock part 90 _X and the Y-axis thermal interlock part 90 _Y did not reach 80 ° C., and the maximum temperatures were 57 ° C. and 55.6 ° C., respectively.

Therefore, as described above, the monitoring temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both set to 60 ° C., and the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y operate. When both temperatures are set to 80 ° C., no interlock is applied during the laser processing of the laser irradiation pattern PA ₂ as in this case, and there is no problem at all. That is, laser processing is performed safely and normally.

[Test pattern 3]

9A and 9B show a case where the laser irradiation pattern PA ₃ is drawn horizontally at the top of the area AR. Also in this case, the temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y did not reach 60 ° C., and the maximum temperatures were 43 ° C. and 35.5 ° C., respectively. On the other hand, the temperatures of the X-axis thermal interlock part 90 _X and the Y-axis thermal interlock part 90 _Y did not reach 80 ° C., and the maximum temperatures were 44 ° C. and 43 ° C., respectively.

Therefore, as described above, the monitoring temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both set to 60 ° C., and the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y operate. When both temperatures are set to 80 ° C., no interlock is applied during the laser processing of the laser irradiation pattern PA ₃ as in this case, and there is no problem at all.

[Test pattern 4]

10A and 10B show a case where the laser irradiation pattern PA ₄ is vertically drawn at the center of the area AR so as to overlap the X coordinate axis (Y = 0). Also in this case, the temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y did not reach 60 ° C., and the maximum temperatures were 55.8 ° C. and 54 ° C., respectively. In contrast, the temperatures of the X-axis thermal interlock portion 90 _X and the Y-axis thermal interlock portion 90 _Y did not reach 80 ° C., and the maximum temperatures were 65 ° C. and 47 ° C., respectively.

Therefore, as described above, the monitoring temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both set to 60 ° C., and the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y operate. When both temperatures are set to 80 ° C., no interlock is applied during the laser processing of the laser irradiation pattern PA ₄ as in this case, and there is no problem at all.

[Test pattern 5]

11A and 11B show a case where the laser irradiation pattern PA ₅ is vertically drawn at the left corner of the area AR. Also in this case, the temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y did not reach 60 ° C., and the maximum temperatures were 51.5 ° C. and 32.8 ° C., respectively. In contrast, the temperatures of the X-axis thermal interlock portion 90 _X and the Y-axis thermal interlock portion 90 _Y did not reach 80 ° C., and the maximum temperatures were 74.8 ° C. and 55 ° C., respectively.

Therefore, as described above, the monitoring temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both set to 60 ° C., and the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y operate. When both temperatures are set to 80 ° C., the laser irradiation pattern PA ₅ is not interlocked during the laser processing of the laser irradiation pattern PA ₅ as in this case, and there is no problem at all.

[Test pattern 6]

12A and 12B show the case where the laser irradiation pattern PA ₆ is vertically drawn at the right corner of the area AR. Also in this case, the temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y did not reach 60 ° C., and the maximum temperatures were 34.6 ° C. and 33.5 ° C., respectively. On the other hand, the temperature of the X-axis thermal interlock part 90 _X did not reach 80 ° C., and the maximum temperature was 38.2 ° C. However, for some reason, the temperature of the Y-axis thermal interlock portion 90 _Y exceeded 80 ° C., and the maximum temperature was 88 ° C.

Therefore, as described above, the monitoring temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both set to 60 ° C., and the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y operate. When both temperatures are set to 80 ° C., the temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both monitored temperatures (60 ° C.) during the laser processing of the laser irradiation pattern PA ₆ as in this time. In spite of not reaching, the interlock is applied from the Y-axis thermal interlock portion 90 _Y , and the laser processing is stopped halfway. Although this is not an original form, the viewpoint of giving top priority to the stability of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y that holds the X-axis galvano mirror 70 _X and the Y-axis galvano mirror 70 _Y with an adhesive. Therefore, it is not a problem.

[Test pattern 7]

13A and 13B show a case where the laser irradiation pattern PA ₇ is drawn at the center of the area AR in a 45 ° oblique direction substantially orthogonal to the surface of the X-axis galvano mirror 70 _X. In this case, the temperature of the X-axis mirror holder 78 _X slightly exceeded 60 ° C. and increased to a maximum of 60.2 ° C. In contrast, the temperature of the X-axis thermal interlock portion 90 _X does not reach 80 ° C., and the maximum temperature is 56.5 ° C., whereas the temperature of the Y-axis mirror holder 78 _Y does not reach 60 ° C. The maximum was 42.2 ° C. On the other hand, for some reason, the temperature of the Y-axis thermal interlock portion 90 _{Y well} exceeded 80 ° C., and the maximum temperature was 110 ° C. or higher.

Therefore, as described above, the monitoring temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both set to 60 ° C., and the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y operate. When both temperatures are set to 80 ° C., during the laser processing of the laser irradiation pattern PA ₇ like this time, the Y-axis thermal interlock unit 90 _{Y is} interlocked, and the laser processing is stopped halfway. . As a result, the adhesive fixing and holding of the X-axis galvanometer mirror 70 _{X in} the X-axis mirror holder 78 _X is protected by this, and it can be said that there is no particular problem.

[Test pattern 8]

14A and 14B show the case where the laser irradiation pattern PA ₈ is drawn at the center of the area AR in a 45 ° oblique direction substantially parallel to the surface of the X-axis galvanometer mirror 70 _X. In this case, the temperature of the X-axis mirror holder 78 _X exceeded 60 ° C. and increased to a maximum of 62.2 ° C. On the other hand, the temperature of the X-axis thermal interlock portion 90 _X exceeded 80 ° C. and increased to a maximum of 94.5 ° C. (estimated value). On the other hand, the temperature of the Y-axis mirror holder 78 _Y did not reach 60 ° C., and the maximum temperature was 42.8 ° C. On the other hand, the temperature of the Y-axis thermal interlock portion 90 _Y did not reach 80 ° C. and was a maximum of 66.2 ° C.

Therefore, as described above, the monitoring temperatures of the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y are both set to 60 ° C., and the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y operate. When both the temperatures are set to 80 ° C., when the laser processing of the laser irradiation pattern PA ₈ as in this time is executed, the temperature of the X-axis mirror holder 78 _X exceeds the monitoring temperature (60 ° C.). In addition, the X-axis thermal interlock unit 90 _X performs the switching operation to apply the interlock, and there is no problem at all.

As described above, the monitoring temperature set for the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y and the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y are set. Although there is some irregularity with the operating temperature, there is a universal correlation as a whole, and it can be experimentally verified that the present invention provides an accurate interlock mechanism with few malfunctions. It was.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above does not limit this invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

For example, in the above embodiment, the thermal switches 94 _X and 94 _Y are used as the temperature sensitive elements of the X-axis thermal interlock unit 90 _X and the Y-axis thermal interlock unit 90 _Y. It is also possible to replace it with a temperature sensor that outputs an electrical signal corresponding to it. In this case, an interlock signal generation circuit that compares the electrical signal from the temperature sensor with a predetermined reference value and outputs an interlock signal when the electrical signal exceeds the reference value (toward the main control unit 18). Is provided in the temperature monitoring unit 58.

  In the scanning laser processing apparatus according to the above-described embodiment, various modifications and changes can be made for each part. For example, the fiber laser oscillator 10 can be replaced with other types or types of laser oscillators (eg, YAG lasers). Laser processing is not limited to seam welding, and the present invention can also be applied to marking processing and the like. Therefore, a Q-switch laser oscillator can be used as the laser oscillator.

Although the accuracy or reliability of the interlock operation is reduced, the temperature monitoring unit 58 may include only one of the X-axis thermal interlock unit 90 _X or the Y-axis thermal interlock unit 90 _Y. When such a single thermal interlock portion is provided, the arrangement position may be further arbitrarily selected. For example, it may be arranged between the X-axis mirror holder 78 _X and the Y-axis mirror holder 78 _Y. is there.

DESCRIPTION OF SYMBOLS 10 Fiber laser oscillator 12 Laser power supply 14 Laser transmission system 16 Laser emission part 18 Main control part 56 _X X-axis galvano scanner 56 _Y X-axis galvano scanner 58 Temperature monitoring part 60 Scanner housing | casing 70 _X X-axis galvanometer mirror 70 _Y Y-axis galvano Mirror 78 _X X-axis mirror holder 78 _Y Y-axis mirror holder 90 _X X-axis thermal interlock 90 _Y Y-axis thermal interlock

Claims (11)

A scanning laser processing apparatus for performing desired laser processing by irradiating a laser beam to a processing point of a workpiece,
A laser oscillation section for oscillating and outputting the laser beam;
A galvano mirror that reflects the laser light from the laser oscillation unit toward the processing point, a mirror holder that holds the galvano mirror, and a rotation drive unit that rotationally drives the galvano mirror via the mirror holder. A galvano scanner with
A scanner casing having a laser emission port for covering and accommodating at least the galvano mirror and the mirror holder of the galvano scanner and emitting the laser beam to the outside;
A temperature monitoring unit having a temperature sensing element disposed in the scanner housing and generating a predetermined interlock signal based on the output of the temperature sensing element when the temperature of the temperature sensing element exceeds a predetermined monitoring temperature When,
A laser processing apparatus comprising: a control unit that stops the oscillation output of the laser beam in the laser oscillation unit in response to the interlock signal generated from the temperature monitoring unit.   The laser processing apparatus according to claim 1, wherein the temperature sensitive element is disposed at a position close to the mirror holder. The mirror holder is disposed at a position where a part of the light entering the scanner casing from the workpiece through the laser emission port is directly exposed,
The temperature sensitive element is disposed at a position where a part of light entering the scanner casing directly from the workpiece through the laser emission port is directly exposed.
The laser processing apparatus according to claim 1 or 2. A scanning laser processing apparatus for performing desired laser processing by irradiating a laser beam to a processing point of a workpiece,
A laser oscillation section for oscillating and outputting the laser beam;
A first galvanometer mirror that reflects the laser light from the laser oscillation section toward a second galvanometer mirror; a first mirror holder that holds the first galvanometer mirror; and the first mirror holder. A first galvano scanner having a first rotation drive unit for rotating the first galvanometer mirror in a first direction via
The second galvanometer mirror that reflects the laser light from the first galvanometer scanner toward the processing point, a second mirror holder that holds the second galvanometer mirror, and the second mirror holder A second galvano scanner having a second rotation driving unit for rotating the second galvano mirror in a second direction orthogonal to the first direction via
A laser emission port for covering and accommodating at least the first and second galvanometer mirrors and the first and second mirror holders of the first and second galvano scanners and emitting the laser beam to the outside; A scanner housing having,
The first and second temperature sensing elements are disposed in the scanner casing at positions relatively close to the first mirror holder and the second mirror holder, respectively. When the temperature exceeds the first monitoring temperature or when the temperature of the second temperature sensing element exceeds the second monitoring temperature, the output of the first temperature sensing element or the second temperature sensing element is set. A temperature monitoring unit for generating an interlock signal based on,
A laser processing apparatus comprising: a control unit that stops the oscillation output of the laser beam in the laser oscillation unit in response to the interlock signal generated from the temperature monitoring unit. The first mirror holder is disposed at a position where a part of the light entering the scanner casing from the workpiece through the laser emission port is directly exposed;
The first temperature sensing element is disposed at a position where a part of the light entering the scanner casing from the workpiece through the laser emission port is directly exposed.
The laser processing apparatus according to claim 4. The second mirror holder is disposed at a position where a part of light entering the scanner casing directly from the workpiece through the laser emission port is exposed;
The second temperature sensitive element is disposed at a position where a part of the light entering the scanner casing from the workpiece through the laser emission port is directly exposed.
The laser processing apparatus according to claim 4 or 5.   The temperature monitoring unit covers the temperature sensing element with a casing made of a material having a light absorption rate higher than that of the mirror holder with respect to light from the workpiece. The laser processing apparatus according to item.   The laser processing apparatus according to claim 7, wherein the mirror holder is made of aluminum and the casing is made of stainless steel. The temperature sensing element comprises a thermal switch that turns on or off a contact of an electric circuit when a preset temperature is reached,
When the temperature of the mirror holder exceeds the monitoring temperature, the thermal switch is turned on or off to generate the interlock signal;
The laser processing apparatus as described in any one of Claims 1-8. The temperature sensing element comprises a temperature sensor that generates an electrical signal having a magnitude corresponding to the ambient temperature,
The temperature monitoring unit includes an interlock signal generation circuit that compares the electrical signal from the temperature sensor with a predetermined reference value and outputs the interlock signal when the electrical signal exceeds the reference value.
The laser processing apparatus as described in any one of Claims 1-8. The laser oscillation unit continuously oscillates the laser beam,
The laser processing according to any one of claims 1 to 10, wherein seam welding is performed by scanning and irradiating the laser beam of a continuous wave to a processing point on a predetermined straight line or a curve set on the workpiece. apparatus.