JP2005081399A - Method and apparatus for preventing contamination inside optical axis in laser machining apparatus and accident control method for laser machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent fume emitted by burning of a lens from giving bad effects such as contamination to each member inside an optical axis when a condenser lens burns out. <P>SOLUTION: When the condenser lens 9 inside a laser machining head 5 burns out during laser machining, the fume emitted during burning inside the laser machining head 5 disposed on the laser entry side to the condenser lens 9 is detected by a lens burning detector 15. Responding to the lens burning detection signal, while emission of the laser beam LB passing through the condenser lens 9 is interrupted by a laser cut-off device 21, a cooling unit 23 to cool the condenser lens 9 is stopped and then the fume inside the laser machining head 5 on the laser entry side is exhausted by a gas exhausting unit 33. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical axis contamination prevention method and its apparatus in a laser processing apparatus, and an accident processing method for a laser processing apparatus.

  The condensing lens used in the laser processing head of the laser processing machine is a transmissive lens used for the purpose of increasing the energy density by condensing the laser beam toward the processing point of the workpiece W. The condensing lens is selected from a material having good transparency so as not to be affected by the heat of the laser beam. For example, common optical glass (BK7, SK16, LF1, etc.) used in the visible light region (0.82 μm to 0.38 μm) as a base material for transmission optical elements such as condensing lenses is a problem with wavelength transmission characteristics. Since it cannot be used, crystals of special substances such as ZnSe (Zinc Selenide) and KCl (Potassium Chloride) are used.

  ZnSe described above is widely used as a condensing lens for carbon dioxide laser processing machines and the like because it does not have the deliquescent property of absorbing and destroying moisture in the atmosphere like KCl and has excellent mechanical strength.

  However, the condensing lens loses its transparency due to deterioration or the like, and heat absorption and focal length change occur, resulting in burning. In ZnSe (Zinc Selenide), the gas generated when overheated is toxic, so the laser beam irradiation must be stopped immediately upon burning.

In particular, dust generated on the incident side when the condensing lens burns out diffuses and adheres to the optical axis of the laser processing head, so that the bellows, the reflection mirror, and the like constituting the optical axis are damaged. Even if the condensing lens is burned out, the emission of the laser beam cannot be stopped unless the burning is detected. Therefore, a method for detecting light emission and smoke generation at the time of burning has been developed as a method for detecting burning of the condenser lens (for example, see Patent Document 1).
JP 2003-129777 A

  By the way, in the conventional burnout detection of the condenser lens, when a phenomenon such as smoke generation or a product is detected as a result of the burnout, smoke generated by the burnout diffuses in the optical axis of the laser processing head. For this reason, there is a problem that the contamination inside the optical axis due to the smoke generated by the above burning cannot be prevented only by detecting the above burning.

  The present invention has been made to solve the above-described problems.

  The method for preventing contamination within the optical axis in the laser processing apparatus according to the present invention is such that when the condensing lens in the laser processing head burns out during laser processing, the laser processing head on the laser beam incident side with respect to the condensing lens during the burning out The smoke generated inside is detected, and the laser burning through the condenser lens is stopped by this lens burnout detection signal, and the cooling device for cooling the condenser lens is stopped, and laser processing on the laser light incident side is stopped. It is characterized by discharging smoke in the head.

  An optical axis contamination preventing method in a laser processing apparatus according to the present invention is the same as in the optical axis contamination preventing method in the laser processing apparatus, in the laser processing head on the laser beam incident side with respect to the condenser lens by the lens burnout detection signal. To seal.

  The anti-pollution device in the optical axis of the laser processing apparatus according to the present invention includes a laser processing head provided with a condensing lens for condensing laser light, and laser light incident on the condensing lens when the condensing lens is burned out. A lens burnout detecting device for detecting smoke generated in the laser processing head on the side, a laser light blocking device for stopping emission of laser light passing through the condensing lens, a cooling device for cooling the condensing lens, Control for causing the laser light blocking device, the cooling device, and the gas discharge device to be controlled by a gas discharge device for discharging smoke in the laser processing head on the laser light incident side and a lens burnout detection signal of the lens burnout detection device And an apparatus.

  An optical axis contamination prevention device in a laser processing apparatus according to the present invention is the optical machining contamination prevention device in the laser processing device, wherein the laser processing head is disposed inside the laser processing head on the laser beam incident side with respect to the condenser lens. A processing head shut-off device for sealing is provided.

  An optical axis contamination prevention apparatus in a laser processing apparatus according to the present invention is the optical axis contamination prevention apparatus in the laser processing apparatus, wherein the gas discharge device includes a dust removal apparatus having a dust removal capability of 0.1 μm or less.

  This laser beam machine accident processing method does not open the optical axis for a predetermined time until exhaust of pollutant gas is completed when the anti-pollution device in the optical axis in the laser processing apparatus of the invention of claim 4, 5 or 6 is activated. The alarm cannot be canceled unless a predetermined time has passed. In addition, after automatic or manual cancellation, the status of the condenser lens is displayed and requested, and the confirmation of the status of the condenser lens is a removal signal. It is made for the first time, and the status confirmation display is erased and a series of alarms are released.

  As can be understood from the means for solving the above problems, according to the present invention, the emission of the laser light passing through the condenser lens is stopped by the lens burnout detection signal of the condenser lens, and Since the cooling device for cooling the optical lens is stopped, there is an effect of slowing the diffusion of smoke into the optical axis. In addition, since the smoke in the laser processing head on the laser beam incident side is discharged, there is an effect of preventing the natural diffusion of the smoke. As a result, it is possible to prevent damage such as the smoke contaminating each member in the optical axis.

  Further, by sealing the inside of the laser processing head on the laser beam incident side by the processing head blocking device by the lens burnout detection signal, there is an effect of further preventing the diffusion of smoke into the optical axis.

  Further, when the optical axis contamination prevention device in the laser processing apparatus is activated, a warning is issued so as not to open the optical axis for a predetermined time until the exhaust of the pollutant gas is completed. Is possible. In addition, after automatic or manual release, the status of the condenser lens is displayed and requested, and the status confirmation of the condenser lens is made for the first time with a detachment signal, the status confirmation display is erased, and a series of alarms can be released. it can.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIG. 1, a laser processing apparatus 1 according to this embodiment includes a laser oscillator 3 that oscillates a laser beam LB, and the laser beam LB oscillated by the laser oscillator 3 is an intensity adjusting device (not shown). Then, the laser beam is reflected in a vertically downward direction via a bend mirror 7 provided in the upper part of the laser processing head 5 provided in the laser processing apparatus 1. This laser beam LB is condensed by a condenser lens 9 provided at the lower part in the laser processing head 5. For example, the focal point of the laser beam LB is focused on the workpiece W that has been transferred and positioned by a numerically controlled workpiece transfer positioning device (not shown), for example, with respect to the irradiation optical axis of the focused laser beam LB. Laser processing such as cutting into a shape is performed.

  The laser processing head 5 has a condensing lens 9 mounted in the tip (lower end) of a housing 11 that forms a cylindrical body, and a nozzle 13 is provided on the exit side of the condensing lens 9.

  In addition, the housing 11 on the incident side with respect to the condenser lens 9 is provided with, for example, a reflective optical sensor 15 as a lens burnout detection device that detects smoke generated when the condenser lens 9 is burnt. As the reflection type optical sensor 15, a coaxial two-core optical fiber is provided on the optical axis in the housing 11 on the incident side (upper part in FIG. 1) of the condenser lens 9, one of which is light from the sensor amplifier 17. Light for detection is emitted into the optical axis through the fiber, and the amount of light reflected from the inner wall of the optical axis is returned to the sensor amplifier 17 and detected by the other optical fiber. In this case, for example, the particle diameter of the smoke is 2 to 3 μm, and the detection light is reflected by the smoke particles due to the smoke, and the increase in the amount of reflected light is amplified by the sensor amplifier 17 using an optical fiber. Thus, burning of the condenser lens 9 is detected. The laser oscillator 3 and the sensor amplifier 17 are connected to the control device 19.

  Further, for example, an oscillator shutter 21 serving as a laser beam blocking device that blocks or opens the emitted laser beam LB is provided at the emission port of the laser oscillator 3. The opening / closing operation of the oscillator shutter 21 is performed according to a command from the control device 19.

  Further, the condenser lens 9 is provided with a cooling device 23 for cooling the condenser lens 9 for the purpose of preventing the focal position fluctuation due to heat. As this cooling device 23, an air supply line 25 for air-cooling by blowing, for example, purge air as a gas on the surface of the condenser lens 9 is provided between the air supply source 27 for supplying purge air and the laser processing head 5. It has been. In the middle of the air supply pipe 25, for example, a switching valve 29 (electromagnetic valve) is provided as a cooling opening / closing device for controlling ON / OFF of purge air supply. This switching valve 29 is connected to the control device 19. The air supply line 25 between the switching valve 29 and the laser processing head 5 constitutes a purge air blowing circuit 31 for blowing gas onto the condenser lens 9.

  Further, the laser processing head 5 is provided with a gas discharge device 33 for discharging smoke generated in the housing 11 on the laser beam incident side with respect to the condenser lens 9. As the gas discharge device 33, a gas discharge pipe 35 for sucking a gas containing smoke inside the optical axis close to the condenser lens 9 communicates with the housing 11 of the laser processing head 5. Is in communication with a vacuum generator 37. That is, the smoke in the housing 11 of the laser processing head 5 is sucked by the vacuum generator 37 via the gas discharge pipe 35 and discharged from the vacuum generator 37 to the outside.

  In this embodiment, the vacuum generator 37 is connected to the switching valve 29 of the cooling device 23 by the air supply pipe 25 to form a vacuum generation circuit 39, and the condenser lens 9 is When the reflection optical sensor 15 detects that the burnout has occurred, the switching valve 29 shuts off the purge air blowing circuit 31 and switches to the vacuum generation circuit 39 simultaneously with the lens burnout detection signal, so that, for example, air is contained in the vacuum generator 37. In this way, the gas discharge pipe 35 is sprayed to the outside so as to have a negative pressure, so that the negative pressure in the gas discharge pipe 35 causes a discharge from the discharge port 40 provided on the side wall of the housing 11 of the processing head 5. Gas such as smoke in the optical axis is sucked and exhausted to the outside.

  Note that the vacuum generator 37 may be connected to the control device 19 so as to operate independently without being operated by the switching valve 29 described above. Moreover, you may be another form of vacuum generator.

  Further, for example, a filter 41 as a dust removing device having a dust removing performance of 0.1 μm or less is provided in the gas exhaust line 35 between the optical axis in the housing 11 and the vacuum generator 37 in order to remove smoke. The filter element of this embodiment is 0.01 μm. Thereby, for example, after the toxic gas of smoke is removed by the filter 41, it is exhausted to the outside.

  Further, the laser processing head 5 is provided with, for example, a processing head shutter 43 as a processing head blocking device that seals the inside of the laser processing head 5 on the laser beam incident side with respect to the condenser lens 9. This processing head shutter 43 is connected to the control device 19 to detect that the condenser lens 9 has been burned out, and at the same time, to seal the inside of the laser processing head 5, smoke and vapor are mainly emitted from the bend mirror 7 and bellows, for example. It is possible to prevent it from diffusing towards the axis.

  Referring to FIG. 2, in the control device 19, an input device 47 such as a keyboard and a display device 49 such as a CRT or LCD are connected to a CPU 45 serving as a central processing unit.

  The CPU 45 is connected to a memory 51 for storing data such as the size and shape of the workpiece W inputted from the input device 47 and a machining program including a laser machining instruction.

  Further, the CPU 45 operates the oscillator shutter 21 to stop the emission of the laser beam LB and the switching valve 29 according to the lens burnout detection signal of the reflective photosensor 15 as a lens burnout detection device, for example. A command unit 53 is connected to give a command to stop cooling the condenser lens 9 and to discharge smoke on the laser beam incident side in the laser processing head 5.

  The command unit 53 can also give a command to the alarm 55 shown in FIG. 2 so as to issue a warning to the operator by a lens burnout detection signal.

  With the above configuration, when the condensing lens 9 in the laser processing head 5 is burned out during laser processing, the smoke generated at the time of this burning is detected by the reflective optical sensor 15. By this lens burnout detection signal, a command is given from the command unit 53 of the control device 19 to each device.

  That is, since the oscillator shutter 21 is operated to block the laser beam LB emitted from the laser oscillator 3, the laser beam LB passing through the condenser lens 9 is stopped. In addition, alarm 55 is activated to alert the operator. In addition, the switching valve 29 of the purge air spray circuit 31 is operated to switch the purge air supplied from the air supply source 27 to the vacuum generator circuit 39 from the purge air spray circuit 31 that cools the condenser lens 9 to the vacuum generator 37. It is done. Accordingly, the supply of purge air to the condensing lens 9 is stopped, and at the same time, the pressure in the gas discharge pipe 35 becomes negative, so that smoke on the laser beam incident side in the laser processing head 5 is discharged from the discharge port 40 to the gas discharge pipe 35. After the smoke is removed by the filter 41 on the way, clean air is discharged to the outside by the vacuum generator 37.

  Accordingly, the supply of purge air to the condenser lens 9 is stopped, so that the diffusion of smoke into the optical axis can be delayed, and the smoke in the laser processing head 5 is immediately discharged. Can be prevented. As a result, it is possible to prevent adverse effects such as contamination of the optical axis members such as the bend mirror 7 and the bellows in the optical axis.

  Further, in addition to the above-described operation, sealing the inside of the laser processing head 5 on the laser beam incident side with the processing head shutter 43 by the lens burnout detection signal prevents smoke from diffusing into the optical axis. There is a further effect.

  According to the actual test results, the lens burnout was detected about 1 second after the condenser lens 9 was burned out, and smoke discharge started almost simultaneously. After passing through the filter 41, the smoke was removed without being visually recognized.

The laser processing head 5, the reflective optical sensor 15 as a lens burnout detection device, the oscillator shutter 21 as a laser light blocking device, the cooling device 23, the gas discharge device 33, the processing head shutter 43 as a processing head blocking device, and dust removal The filter 41 and the control device 19 as a device constitute an optical axis contamination prevention device in the laser processing machine, and when the optical axis contamination prevention device in the laser processing machine is activated, a predetermined time until exhausting of the contaminated gas, An alarm is issued not to open the optical axis. The alarm cannot be canceled unless a predetermined time has elapsed. Further, after the automatic or manual release, the state of the condenser lens 9 is displayed / requested on the display device 49, and the state confirmation of the condenser lens 9 is made for the first time with the detachment signal. Cleared and a series of alarms can be released.

  In addition, this invention is not limited to embodiment mentioned above, It can implement in another aspect by making an appropriate change. The present invention is widely used not only for a simple laser processing apparatus but also for a composite processing apparatus for plate materials provided with a laser processing apparatus.

It is a schematic explanatory drawing of the laser processing apparatus of embodiment of this invention. It is a block block diagram of a control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 3 Laser oscillator 5 Laser processing head 7 Bend mirror 9 Condensing lens 15 Reflection type optical sensor (lens burnout detection apparatus)
19 Control device 21 Oscillator shutter (laser light blocking device)
23 Cooling device 29 Switching valve (Cooling switch)
33 Gas exhaust device 37 Vacuum generator 41 Filter (dust removal device)
43 Processing head shutter (processing head shut-off device)
53 Command section 55 Alarm

Claims (6)

  When the condensing lens in the laser processing head burns out during laser processing, smoke generated in the laser processing head on the laser beam incident side with respect to the condensing lens is detected at the time of this burning, and this lens burnout detection signal A laser processing apparatus that stops emission of laser light passing through the condenser lens, stops a cooling device that cools the condenser lens, and discharges smoke in the laser processing head on the laser light incident side. To prevent contamination in the optical axis.   2. A method for preventing contamination in an optical axis in a laser processing apparatus according to claim 1, wherein the laser processing head on the laser beam incident side with respect to the condensing lens is sealed by the lens burnout detection signal. A laser processing head having a condensing lens for condensing laser light therein, and a lens burnout for detecting smoke generated in the laser processing head on the laser beam incident side with respect to the condensing lens when the condensing lens burns out A detection device, a laser light blocking device that stops emission of laser light that passes through the condenser lens, a cooling device that cools the condenser lens, and smoke in the laser processing head on the laser light incident side is discharged. A gas discharge device, and a control device that controls the laser light blocking device, the cooling device, and the gas discharge device according to a lens burnout detection signal of the lens burnout detection device;
An optical axis contamination prevention device in a laser processing apparatus comprising:   4. The laser processing apparatus according to claim 3, wherein the laser processing head is provided with a processing head blocking device that seals the inside of the laser processing head on the laser beam incident side with respect to the condenser lens. apparatus.   5. The apparatus for preventing contamination in an optical axis in a laser processing apparatus according to claim 3, wherein the gas discharging device is provided with a dust removing device having a dust removing ability of 0.1 [mu] m or less.   When the anti-pollution device in the optical axis in the laser processing apparatus of claim 4, 5 or 6 is activated, an alarm is issued not to open the optical axis for a predetermined time until the exhaust of pollutant gas is completed, and the alarm has passed for a predetermined time. Otherwise, after the automatic or manual release, the status of the condenser lens is displayed and requested, and the status confirmation of the condenser lens is made for the first time with the removal / desorption signal, and the status confirmation display is erased, A laser beam machine accident handling method, wherein a series of alarms are released.

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