JP7118160B2 - Ignition detection method and ignition detection device - Google Patents

Description

The present invention relates to an ignition detection method and an ignition detection device.

_CO2 lasers are easily absorbed by non-metals. Nearly 100% absorption is achieved by materials such as paper, wood, acrylic, rubber, and leather, making it highly energy efficient and capable of cutting thick workpieces with less laser energy. For example, a 40 W CO ₂ laser can cut an acrylic resin plate with a maximum thickness of 10 mm in one laser cutting process.

For this reason, CO ₂ laser processing machines are used in various fields, and are often used not only in metal processing but also in non-metal processing. In metal processing applications, fires rarely occur because the workpieces are metal, but in non-metal processing applications, especially in the cutting mode (vector mode) that cuts the workpiece into a predetermined shape, laser The energy of the material stays in one place for a long time, and at the same time, non-metallic materials usually have flammable physical properties, so there is a possibility of fire due to ignition of the work piece.

A study was conducted on detection of ignition and fire prevention of workpieces in a general-purpose laser processing machine. For example, Chinese Patent No. CN201822174251.8 describes a laser cutting device with a flame detector. In this application, a flame detector is installed on the workbench of the laser cutting machine in order to realize real-time monitoring of the non-metallic material workpiece. To realize the purpose of warning and notifying workers when flames occur. However, since the design emphasis in this application was on the easy installation and removal of the internal parts of the laser cutting machine, the sensitivity and accuracy of firing detection were not studied. Similarly, China Publication No. CN2513710Y describes the invention of fire alarm device for laser cutting engraving machine. Installed, the heat generated during processing is exhausted by a blower to prevent the occurrence of flames, and when a flame is detected, the worker is warned, and the effect of fire prevention and alarm is demonstrated. Also, from this patent, it can be seen that prior to 2002, there was a way to implement a fire detection function in a laser processing machine.

Chinese Patent No. CN201510311657.4 introduces a laser cutting engraving machine with fire safety mechanism. In this application, a fire safety mechanism is installed inside the processing machine, and the mechanism comprises a fire source detection part, a fire extinguishing part and a control part. In which, the control part is electrically connected to the flame sensing part and the extinguishing part, receives and processes the signal sent by the flame sensing part, determines whether there is ignition in the processing machine, and the extinguishing part control behavior. When the workpiece catches fire, the fire extinguishing part can be operated to extinguish the fire. A smoke sensor, a light sensor of a specific wavelength, a flame sensor, or a specific gas sensor can be used as the flame sensor.

Chinese Patent No. 201822174251.8 Chinese Publication No. 2513710Y Chinese Patent No. 201510311657.4

Although the above Patent Document 3 describes that the purpose of extinguishing the fire quickly can be achieved, an examination of the main configuration reveals the feature that the fire extinguishing section is installed near the processing machine. However, there was no description of how to detect ignition quickly and accurately in the early stages of ignition.

According to the present invention, for laser processing of various non-metal workpieces W, in the laser processing process of a laser processing machine, ignition of the workpiece W is detected as early as possible to suppress the occurrence of fire. A detection method and an ignition detection device can be provided. In addition, the present invention has good versatility because it does not require changes in ignition detection setting methods due to differences in machine size, processing speed, laser output power, type of laser oscillator, and the like.

To achieve the above objectives, the technical methods provided by the present invention are as follows.
The present invention includes a laser output signal acquisition process for acquiring a laser output signal from a laser oscillator during laser processing, and a flame detection process for acquiring a flame detection signal Q obtained by detecting a flame generated by laser irradiation on a workpiece W. and the laser output signal and the flame detection signal Q, and when the laser is output according to the laser output signal, the duration of the single laser output signal and the flame detection signal of the single laser output signal duration. Based on the total number of detections of Q, it is judged whether or not the device is in an abnormal state of ignition and combustion. and an ignition combustion determination step of determining whether or not the device is in an abnormal state of ignition and combustion, based on the total number of detections.
Further, the present invention comprises a laser output signal acquisition unit for acquiring a laser output signal of the laser oscillator during laser processing, a flame detection unit for detecting flame generated by laser irradiation to the workpiece W, and the flame detection unit. a flame detection signal acquisition unit for acquiring a flame detection signal Q obtained by detecting a flame; and a duration of a single laser output signal and a single laser output when the laser is output according to the laser output signal. Based on the total number of flame detection signals Q detected during the duration of the signal, it is determined whether the device is in an abnormal state of ignition and burning, and when the laser output signal is not outputting the laser. and a combustion judgment unit for judging whether or not the device is in an abnormal state of ignition and combustion based on the total number of flame detection signals Q detected during the cumulative detection period TM. is.

By using the technical method provided by the present invention, the following effects can be obtained compared with the existing technology.

(1) The ignition detection method of the present invention utilizes the flame detection signal Q detected when the laser is not output by the laser output signal and when the laser is output by the single laser signal. The characteristics of are accumulated as important grounds and used as the final judgment criteria for ignition combustion. The detection method does not change due to differences in equipment size, processing speed, laser output power, laser type, etc., and has excellent versatility.

(2) In the ignition detection method of the present invention, in the raster mode (engraving mode), it is set that an alarm will not be issued unless the flame detection signal Q is continuously obtained at least at a plurality of line feeds. This makes it possible to correctly determine firing within a few seconds and at the same time rationally cancel the noise signal, thereby fundamentally avoiding erroneous determination. In vector mode (cutting mode), various machining conditions are also monitored. That is, it can detect flames when a single laser signal is on and when the laser is off, detect material ignition both when the laser is on and off, and make an accurate decision within seconds. It can be carried out. According to the above method, in the laser processing of the laser processing machine, it is possible to detect the ignition of the workpiece W as early as possible and suppress the occurrence of the fire. Moreover, by setting the detection exclusion period, the noise signal due to the residual spark can be further canceled, and the detection accuracy can be improved.

(3) In the ignition detection method of the present invention, the material determination period T2 is set, and after the single laser output signal becomes an output state, the flame is detected by the flame detection signal Q during the first material determination period T2. , it is determined that there is a possibility that the workpiece W is likely to generate sparks. With this method, when laser processing is performed on a workpiece W containing a material that easily generates sparks, such as silicon or alumina, the material determination period T2 is used to prevent an erroneous determination that sparks are erroneously detected as ignition combustion. can be avoided.

(4) The ignition detection method of the present invention sets a predetermined period T3, and when the output period of the laser output by a single laser output signal reaches or does not reach the predetermined period T3, the total number of detected flame detection signals Q is It is determined whether or not there is an abnormal state of ignition and combustion depending on whether or not the cumulative predetermined amount C3 has been reached. With this method, even if one laser cutting signal (cutting line segment) is long, for example, even if it takes 10 minutes or more from the start of laser irradiation to the end of irradiation, there is no need to wait until the end of laser irradiation. A flame that causes a fire can be detected by the laser output signal while the laser is being output, and the detection period can be secured without missing the timing of ignition detection.

(5) In the ignition detection method of the present invention, the detection period T4 after processing is set for a problem that is easily overlooked by workers, such as ignition when the laser processing machine enters a standby state or a stop state, and detection is performed. When the time reaches or does not reach the detection period T4 after processing, whether the total detection number of the flame detection signal Q reaches the cumulative predetermined amount C4, whether it is in an abnormal state of ignition and combustion. to judge. With this method, it is possible to effectively avoid the risk of the flame not being detected when the workpiece W ignites at the moment the laser processing ends.

(6) In the ignition detection method of the present invention, when the operator changes the setting of the laser output power during the predetermined period T3, the counter and the timer are reset, and the time when the laser output power changes is used as the start time. start over. By this method, when the laser is output by a single laser output signal, it is possible to avoid erroneously detecting sparks as ignition combustion by changing the laser output power by the operator.

(7) The ignition detection method of the present invention fully considers various ignition situations during use of the laser processing machine. Even if the processing method and laser output signal are different between raster mode (engraving mode) and vector mode (cutting mode), flames that cause ignition combustion (fire) can be accurately detected. This method can avoid erroneous determination that sparks are erroneously detected as ignition combustion, and can avoid malfunction of the fire extinguishing system when it is not ignition combustion. Finally, unattended operation of the laser processing machine can be realized.

(8) In the ignition detection device of the present invention, the intake port and the exhaust port are such that external ultraviolet rays cannot directly reach the flame detection part of the laser processing machine even if the device is irradiated from any angle outside the main body of the device. For this reason, an ultraviolet light shielding wall is provided to shield ultraviolet rays. In addition, the positions of the intake port and the exhaust port are higher than the surface of the object to be processed, and smoke powder and dust generated from the object to be processed W are quickly exhausted by the airflow. At the same time, the direction of the airflow entering the inlet is set so that the airflow entering the apparatus main body flows along the inside of the apparatus main body, forming an annular airflow inside the laser processing machine, which is generated from the workpiece W By guiding the smoke and dust away from the flame detection section, the smoke does not affect the detection sensitivity of the flame sensor, and the flame detection section can correctly detect the ultraviolet rays caused by the flame.

FIG. 1 is a perspective view showing a laser processing machine provided with an ignition detection device according to an embodiment of the present invention. FIG. 2 is a block diagram showing a laser processing apparatus equipped with a laser processing machine having an ignition detection device according to an embodiment of the present invention. FIG. 3 is a schematic side view showing a laser processing machine provided with an ignition detection device according to an embodiment of the present invention. FIG. 4 is a diagram showing a configuration for preventing ultraviolet rays from entering the main body of a laser processing machine provided with an ignition detection device according to an embodiment of the present invention, and a configuration for an annular exhaust gas flow. FIG. 5 is an explanatory diagram showing the operating principle of the ultraviolet phototube sensor of the ignition detection device according to the embodiment of the present invention. FIG. 6 is an explanatory diagram showing the principle of operation of the sensor drive board circuit of the ignition detection device according to the embodiment of the present invention. FIG. 7 is a diagram showing waveforms for fire detection in the ignition detection device according to the embodiment of the present invention. FIG. 8 is an explanatory diagram showing an example of a processing method in raster mode. FIG. 9 is an explanatory diagram showing a machining path in a machining method in vector mode. FIG. 10 is another explanatory diagram showing a machining path in the machining method in the vector mode. FIG. 11 is a diagram illustrating a method of determining ignition combustion when the duration of a single laser output signal is relatively short in an ignition detection device according to an embodiment of the present invention. FIG. 12 is a diagram showing a flame detection signal Q due to residual sparks when the laser output signal is long in the ignition detection device according to the embodiment of the present invention. FIG. 13 is a diagram showing a flame detection signal Q due to residual sparks when the laser output signal is short in the ignition detection device according to the embodiment of the present invention. FIG. 14 is an explanatory diagram showing an effective detection period TA for judging ignition combustion in the ignition detection detector according to the embodiment of the present invention. FIG. 15 is a diagram showing the detection exclusion period TE in the disconnection mode (vector mode) in the ignition detection device according to the embodiment of the present invention. FIG. 16 is a diagram showing the detection exclusion period TE in the engraving mode (raster mode) of the ignition detection device according to the embodiment of the present invention. FIG. 17 is a diagram showing the material determination period T2 when the single laser output signal is relatively long in the ignition detection device according to the embodiment of the present invention. FIG. 18 is a diagram showing an ignition combustion judgment method when a single laser output signal is relatively long in the ignition detection device according to the embodiment of the present invention. 19A and 19B are explanatory diagrams showing classification of the ignition/combustion determination method in each situation in the ignition detection/detection device according to the embodiment of the present invention.

An embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a laser processing machine 1 is a laser processing machine using an infrared region laser, which can perform laser processing on a workpiece W composed of various materials such as paper and acrylic. 1, and constitutes a laser processing apparatus together with a flame detection unit 70 and a combustion determination unit 80 (see FIG. 2) provided in the laser processing machine 1. FIG.

The laser processing machine 1 includes an apparatus main body 10 and an oscillator case that houses a laser oscillator (not shown). In the following description, the direction from the back wall 12 to the front wall 11 of the device main body 10 is defined as the front direction, the opposite direction is defined as the rear direction, and these are defined as the front and rear directions. Also, the direction from the second side wall 16 to the first side wall 15 in FIG. 1 is defined as the left direction, the opposite direction is defined as the right direction, and these are defined as the left and right directions. Further, the direction from the lower wall 14 to the upper wall 13 in FIG. 1 is defined as the upward direction, the opposite direction is defined as the downward direction, and these are defined as the vertical direction.

The apparatus main body 10 has a rectangular parallelepiped shape, and has a front wall 11, a rear wall 12, an upper wall 13, a lower wall 14, a first side wall 15, and a second side wall 16, as shown in FIG. The inner wall 12, the upper wall 13, the lower wall 14, the first side wall 15, and the second side wall 16 are formed by coating metal sheets. In addition, in FIG. 1, the 2nd side wall 16 is made transparent and illustrated for convenience of explanation.

The first side wall 15 and the second side wall 16 face each other, and the upper wall 13 and the lower wall 14 face each other. The lower end of the front wall 11 , the lower end of the rear wall 12 , the lower end of the first side wall 15 , and the lower end of the second side wall 16 are all connected to the lower wall 14 . A main body opening 101 is formed over the upper portion of the front wall 11 in a portion near the front side of the upper wall 13 . A top cover 132 (access panel) is rotatably supported with respect to the top wall 13 via a pair of hinges 131 at the rear portion of the top wall 13 . The upper lid 132 has substantially the same shape as the body opening 101 and can close the body opening 101 .

The inner surface of the front wall 11, the inner surface of the rear wall 12, the inner surfaces of the upper wall 13 and the upper lid 132, the inner surface of the lower wall 14, the inner surface of the first side wall 15, and the inner surface of the second side wall 16 are surrounded by the main body of the apparatus. A machining space 102 inside 10 is formed. A workpiece W to be laser-processed (see FIG. 3) is arranged in the processing space 102 and is laser-processed. An exhaust port is formed in the inner wall 12 . One end of an air hose (not shown) is connected to the outside of the inner wall 12 . An exhaust blower (not shown) is connected to the other end of the air hose, and the exhaust blower is driven during laser processing, sucking air into the processing space 102 by means of the exhaust blower. The smoke, dust, and odor generated in the process space 102 are exhausted to the outside.

As shown in FIG. 4, an air intake port is formed in the front part of the device main body 10 as a housing of the laser processing machine, and an exhaust port is formed in the rear part of the device main body 10, in which the flame detection unit is housed. formed. As indicated by an arrow A, air flows into the processing space 102 inside the apparatus main body 10 through the air intake port, passes through the processing space 102, and is exhausted to the outside of the apparatus main body 10 through the exhaust port. As shown in FIG. 4, the intake port and the exhaust port are composed of two walls serving as ultraviolet shielding walls that are parallel in the vertical direction and the horizontal direction. The wall portion as the ultraviolet shielding wall shields the ultraviolet rays from the outside of the apparatus main body 10 from the intake port and the exhaust port to the processing space 102 within the apparatus main body 10 . The upper lid 132 (access panel) is made of a resin plate that blocks ultraviolet light with a wavelength of 180 nm to 260 nm while transmitting visible light. Due to the above-described features, the apparatus main body 10 realizes that air flows into the processing space 102 in the apparatus main body 10 from the intake port, passes through the processing space 102, and is exhausted to the outside of the apparatus main body 10 from the exhaust port. However, it is possible to shield the ultraviolet rays from all angles outside the device main body 10 and avoid malfunction of the flame detection section 70 due to the detection of the ultraviolet rays outside the device main body 10 .

The smoke and dust particles generated during processing are very small, but they absorb ultraviolet light. If the inside of the main body of the laser processing machine 1 is filled with smoke or dust during processing, the flame detection section 70 cannot detect the flame detection signal Q normally. As shown in FIG. 4, in this embodiment, the laser processing machine 1 is provided with air inlets and air outlets on the front and back sides thereof. At the same time, the height of the intake port and the exhaust port must be higher than the surface of the workpiece W. During processing by the laser processing machine 1, the air flow from the intake port to the exhaust port functions on the workpiece W, and smoke and dust generated from the workpiece W flow from the intake port to the exhaust port. This is because they are caught in the air current and immediately exhausted.

As shown in FIG. 4, in this embodiment, the direction of the airflow entering the apparatus body is set by customizing the angle of the UV shielding wall of the inlet of the apparatus main body 10, so that the airflow entering the apparatus main body lead to flow along the inside of the As a result, the air entering the processing space 102 forms an annular exhaust airflow A inside the laser processing machine 1, and the airflow A entering the device main body 10 from the intake port of the front wall 11 of the laser processing machine directly flows into the flame. It does not flow to the detection unit 70 and the exhaust port, but after passing through the intake port, flows upward along the upper lid 132 to the exhaust port of the back wall 12 . As shown in FIG. 4, the airflow A flows from the front wall 11 to the back wall 12, and the part of the airflow B that is not exhausted from the exhaust port flows toward the workpiece W, along the surface of the workpiece W. It flows to the front wall 11 and merges with the airflow A again. The airflow B entrains smoke and dust generated on the surface of the workpiece W during laser processing, flows to the front wall 11, joins the airflow A near the intake port, and is finally exhausted from the exhaust port.

Due to the circulating airflow A formed in the apparatus main body 10, smoke and dust generated from the surface of the workpiece W during laser processing flow from the back wall 12 toward the front wall 11 and away from the flame detector 70. - 特許庁By such a method, it is possible to effectively avoid deterioration in detection sensitivity of the flame sensor due to smoke and dust flowing toward the flame detection section 70 .

According to the above method, when a flame containing ultraviolet rays is generated in the workpiece W, the ultraviolet rays are not absorbed by smoke or dust, and the flame detection unit 70 can accurately detect the ultraviolet rays emitted from the flame. Fire detection ability can be guaranteed.

A guide rail 30 is provided in the machining space 102 . As shown in FIG. 1, the guide rails 30 extend in the left-right direction so as to bridge the pair of front-rear direction rails 31 (Y-axis rails) disposed at the left and right ends of the machining space 102, respectively. and a left-right direction rail 32 (X-axis rail). The left-right direction rail 32 can move in the front-rear direction with respect to the front-rear direction rail 31 while maintaining a parallel positional relationship in the left-right direction. The left-right rail 32 is provided with a workpiece facing portion (laser head) 33 that can move along the left-right rail 32 . A reflecting mirror that reflects the laser beam is provided on the portion facing the processed portion 33, and reflects the laser beam emitted from a laser oscillator and a laser pointer (not shown) so that the height can be adjusted as shown in FIG. The workpiece W placed on the processing table section 50 is vertically irradiated with the laser. The left-right direction rail 32 and the workpiece facing portion 33 are moved by being driven by a motor 36 so that a predetermined position of the workpiece W is irradiated with the laser beam.

Inside the processing space 102 , near the back wall 12 , there are a lower case 40 each having a rectangular parallelepiped shape made of metal, a radiator 60 , and an oscillator case (not shown) extending upward from the lower wall 14 . They are provided in order along the back wall 12 .

An oscillator case (not shown) accommodates a laser oscillator (not shown). The laser oscillator is composed of, for example, a laser oscillator that emits CO ₂ laser. The laser oscillator is not limited to a _CO2 laser, but may be a visible light laser, a fiber laser, or any laser that reacts to the material to process the material. The illustrated laser oscillator is supported by a pair of pedestals (not shown) inside a metal rectangular parallelepiped oscillator case.

A flame detector 70 including an ultraviolet phototube sensor 71 and a sensor drive board 72 is provided inside the device main body 10 and in the right part of FIG. 3 (the rear part of the laser processing machine 1). The flame detection unit 70 composed of the ultraviolet phototube sensor 71 and the sensor driving board 72 is housed in a closed structure housing made up of a sealed metal box 701 and a front window 702 made of glass. A combustion determination unit 80 (main control board), which will be described later and is not illustrated, is not housed in the housing. The size of the front window 702 is configured to be larger than the detection angle of the ultraviolet phototube sensor 71 without blocking the detection range of the ultraviolet phototube sensor 71 .

The sealed metal box 701 is a part for fixing the ultraviolet phototube sensor 71 and the sensor drive board 72, and the front window 702 made of glass protects the ultraviolet light of a specific wavelength contained in flames or sparks, specifically from 180 nm to 180 nm. It is made of quartz glass that transmits ultraviolet rays with a wavelength of 260 nm. The size of the front window 702 is formed to an appropriate size so that the flame generated at any position in the processing space 102 reaches the ultraviolet phototube sensor 71 .

With this configuration, it is possible to prevent smoke, dust, and tar generated from the material from entering the main body of the processing machine. That is, the ultraviolet phototube sensor 71 and the sensor drive board 72 can be prevented from being exposed to smoke, dust, and tar generated from the material during laser processing, and the flame detection section 70 can perform stable detection and long-term operation. Longevity can be achieved.

The flame detection unit 70, which is composed of the ultraviolet phototube sensor 71 and the sensor drive board 72, is fixed at a position higher than the workpiece W and lower than the laser head in the height direction, and lower than the workpiece W in the front-rear direction. It is fixed at a position behind and forward of the back wall 12, and is fixed at the center of the processing area in the processing space 102 (the center position of the workpiece W) in the left-right direction.

By providing the flame detection unit 70 at this position, the maximum flame detection field can be obtained, and at the same time, the flame generated in the workpiece W, etc. It is configured to prevent detection from being interrupted.

Although the flame detection unit 70 can generate the flame detection signal Q immediately after acquiring the ultraviolet light, electrostatic discharge occurs to some extent between parts in the laser processing machine. Since this non-flame discharge also radiates ultraviolet rays, it is preferable to subject the flame detection signal Q to noise removal processing.

The combustion detection system of the laser processing machine includes a flame detection section 70 and a combustion determination section 80. The flame detection section 70 and the combustion determination section 80 are electrically connected using a signal cable or the like.

The flame detection unit 70 includes an ultraviolet phototube sensor 71 and a sensor drive board 72 and is installed at the top inside the lower case 40 .

The combustion determination unit 80 is incorporated in a main control board (not shown) of the apparatus main body 10, which is provided separately from the sensor drive board 72 housed in a metal sealed metal box 701, and is connected to electrical parts such as electrical wiring and power supply. placed in close proximity. Since the main control board of the apparatus main body 10 also generates a signal for driving the motor 36 that drives the left-right direction rail 32 and the part facing the workpiece 33 and a laser output signal for driving the laser oscillator, the laser output signal acquisition unit can obtain the laser output signal directly from the main control board.

The flame detection unit 70 drives the sensor discharge signal of the ultraviolet phototube sensor 71 obtained by detecting ultraviolet rays of a specific wavelength (ultraviolet rays with a wavelength of 180 nm to 260 nm) contained in the flame generated by the laser irradiation of the workpiece W. Acquired by the substrate 72, an electronic circuit composed of parts such as counters and timers on the sensor driving substrate 72 removes non-flame noise signals (such as ultraviolet rays other than flame properties due to electrostatic discharge), and then outputs the flame detection signal Q ( A flame detection signal Q) in FIG. 7 is generated.

The flame detection signal Q generated by the flame detection unit 70 is transmitted to the combustion determination unit 80 by the sensor drive board 72, and the flame detection signal Q is processed and determined in the combustion determination unit 80 constituting the flame detection signal acquisition unit. done.

According to this embodiment, the flame detection unit 70 detects ultraviolet rays in a sampling period of 25 ms, but after detecting ultraviolet rays in one sampling period, it cannot detect ultraviolet rays until the next period. As shown in FIG. 7, a noise elimination circuit is employed which generates a flame detection signal once when ultraviolet light (sensor discharge signal) is detected three times within one sampling period. According to the detection method, when combustion occurs and ultraviolet rays can be detected continuously, the flame detection signal Q can be generated once every approximately 75 ms at maximum.

Combustion determination unit 80 is configured by a control device such as a CPU, and includes a warning unit 81 configured by a device for telephone and mail transmission, an external device (buzzer, etc.), and a display unit 82 (warning lamp, electronic bulletin board, etc.). ), and is electrically or wirelessly connected to a personal computer PC outside the laser processing machine 1 for controlling the laser processing machine 1 .

Since the non-metal workpiece W is likely to spark or ignite during laser irradiation, the combustion determination unit 80 compares the laser output signal and the flame detection signal Q, and determines when the laser is not output according to the laser output signal. Laser non-output period T1 during which no laser is output by the laser output signal (raster mode: period during which no laser is output in each line and line feed period, vector mode: line segment When a flame is detected by the flame detection signal Q during the period of movement between (objects), the combustion determination unit 80 determines that there is a possibility of an abnormality in which the device ignites and burns. of flame detection signals Q are accumulated. When the cumulative time of the non-output period T1 of the laser reaches the cumulative detection period TM, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount CM, the timer and counter are reset and the cumulative detection period TM is reached. The flame detection signal Q continues to be detected in units of . When the cumulative time of the laser non-output period T1 has not reached or has reached the cumulative detection period TM, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount CM, an abnormal state of ignition and combustion. is determined, and control is performed to issue a warning in at least one of the warning section 81 and the display section 82 .

The warning in the warning unit 81 and the display unit 82 is, for example, a buzzer as the warning unit 81 to warn of a fire due to combustion, and a screen displayed by software as the display unit 82 to display the warning of a fire due to combustion. Further, for example, a telephone as the warning unit 81, an e-mail as the display unit 82, or a warning through an external device is performed. Furthermore, it may be configured to be linked with a fire extinguishing system for extinguishing a fire signal caused by combustion to extinguish the fire.

Next, the ultraviolet phototube sensor 71 and the sensor drive board 72 included in the flame detection section 70 will be described.

The ultraviolet phototube sensor 71 of the flame detector 70 detects weak ultraviolet rays of a specific wavelength in the flame. The ultraviolet phototube sensor 71 operates by power supply from the sensor drive board 72 . A DC/DC converter is provided on the sensor drive board 72, and the DC/DC converter oscillates a voltage of one pulse at intervals of 25 ms (40 Hz), for example, and passes the voltage between the anode and the cathode of the ultraviolet phototube sensor 71 through a step-up transformer. is applied with a voltage of about 400V. (This voltage value is determined by the operating voltage of the UV photoelectric sensor and can be adjusted according to the operating specifications of the sensor.)

The ultraviolet phototube sensor 71, as shown in FIG. 5, is a type of gas-filled discharge tube that discharges when ultraviolet light of a specific wavelength is incident. A voltage is supplied to the ultraviolet phototube sensor 71 between a photocathode (cathode) sensitive only to ultraviolet rays of a specific wavelength and an anode. When ultraviolet light is incident on the cathode of the ultraviolet phototube sensor 71, photoelectrons (electrons) are emitted from the surface of the cathode due to the photoelectron emission effect. Photoelectrons are attracted to the anode by electrolysis.

Here, if the supply voltage is increased to strengthen the electrolysis, the photoelectrons are accelerated and collide with the gas molecules in the tube, until they are ionized. Of the electrons and positive ions generated by ionization, the electrons repeatedly collide with other gas molecules and ionize to reach the anode. On the other hand, positive ions are accelerated toward the cathode and collide with the cathode to generate secondary electrons. By repeating this phenomenon, a large current suddenly flows between the anode and the cathode, resulting in a discharge state. This phenomenon is called gas multiplication. The ultraviolet phototube sensor 71 uses gas multiplication to amplify the current and extract the discharge signal of the sensor.

The UV phototube sensor 71 has multiple voltage states as follows.
Discharge starting voltage V _L :
It is the minimum voltage required to cause discharge when ultraviolet rays of a specific wavelength are incident. If this voltage is not reached, discharge will not occur even if ultraviolet rays are incident.
Discharge sustaining voltage V _S :
This is the minimum voltage required to maintain the discharge phenomenon when ultraviolet light is incident and discharge begins. Discharge stops when the voltage across the ultraviolet phototube sensor 71 drops below the discharge sustaining voltage _VS.

More specifically, when ultraviolet rays of a specific wavelength are incident on the ultraviolet phototube sensor 71, the sensor discharges up to the discharge sustaining voltage _VS. A resistor and a capacitor are placed in the cathode discharge path of the ultraviolet phototube sensor 71. When the sensor discharges, a narrow pulse voltage is generated across the resistor, and the flame detector 70 acquires this pulse voltage as a sensor discharge signal.

The output pulse waveform of the ultraviolet phototube sensor 71 is exactly the same regardless of whether it is caused by incident ultraviolet rays or by noise discharge signals other than flames (such as ultraviolet rays other than flames caused by electrostatic discharge). They cannot be distinguished by the waveform of the discharge signal. Therefore, the noise is removed by paying attention to the pulse generation frequency (pulse interval). Below, T ₁ and T ₂ are defined as follows.
_T1 : Gate timer setting time. (e.g., 2 seconds; you may set it to 1 second, 3 seconds, 4 seconds, 5 seconds, or more)
_T2 : Flame detection signal Q duration. (For example, 10 ms. You can set it to any length)

The sensor drive board 72 has a signal processing circuit shown in FIG. Points a, b, and c in the signal processing circuit are as follows.
Point a: A sensor discharge signal from the ultraviolet phototube sensor 71 enters the gate timer and the counter at the same time. The counter counts pulses sequentially.
Point b: If the gate timer continues to receive pulses at intervals shorter than the set time T1 (for example, ₂ seconds), it continues to maintain the OPEN state, but if the pulse _interval exceeds T1, it closes the gate and resets the counter.
Point c: If pulses are input continuously, the counter accumulates the count. When the set value (for example, three times) is reached, a pulse signal of the flame detection signal Q is generated in the output circuit, and the counter is reset.
Point d: In the output circuit, the output pulse from the counter is widened to a required time width T ₂ (for example, 10 ms), output as a flame detection signal Q, and sent to the combustion determination section 80 .

The setting of the gate timer set time T ₁ (eg, 2 seconds) and the counter set value (eg, 3 times) is merely an example. For example, these settings may be adjusted by the frequency of the noise discharge signal. For example, if the gate timer set time T1 is set to ₁ second and the counter set value is set to 2, the flame detection signal Q will be output by detecting the sensor discharge signal twice in 1 second.

In this embodiment, the drive section of the sensor drive board 72 performs sampling periodically, and detects ultraviolet rays once in one sampling period. A sampling period is 25 ms. In the sensor driving board 72 connected to the ultraviolet phototube sensor 71, when ultraviolet rays are detected three times in two seconds (see the "schematic counter level diagram" in FIG. 7), a 10 ms flame detection signal Q ("flame detection signal" in FIG. 7) is generated. ) is output once, and if the number is less than 3 times in 2 seconds, the timer is reset. This eliminates incidental ultraviolet noise (non-flame ultraviolet light generated by electrostatic discharge) in the space. When the UV phototube sensor 71 continuously senses UV light, the UV phototube sensor 71 detects UV light in every sampling period. In this case, one flame detection signal Q is output to the combustion determination unit 80 at maximum 75 ms (hereinafter referred to as "saturation detection amount"). By changing the gate timer setting time _T1 and the counter setting value in the sensor drive board 72 according to the frequency of occurrence of environmental noise, the sampling period is changed and the saturation detection amount is also changed.

The above steps are to remove non-flame UV noise due to electrostatic discharge. The characteristic of this noise is that it is characteristic of electric discharge and does not generate flames.

Processing modes in laser processing include a raster mode (engraving mode) and a vector mode (cutting mode). In the raster mode, as shown in FIG. 5, laser irradiation is performed so as to paint over a predetermined processing area from the start point to the end point.

More specifically, laser irradiation is performed in a straight line from one end to the other end of the predetermined processing area. Next, it moves (line feed) in a direction perpendicular to the direction connecting the one end and the other end. Next, laser irradiation is performed in a straight line from the other end to one end of the predetermined processing region. Next, it moves (line feed) in a direction perpendicular to the direction connecting the other end and the one end. By repeating the above steps, laser irradiation is performed so as to fill the predetermined processing area from the start point to the end point. In the line feed operation in the raster mode, firing can be detected by obtaining a laser non-output period T1 of a uniform length.

In the vector mode, as shown in FIGS. 9 and 10, laser irradiation is continuously performed from the start point to the end point in a so-called single-stroke drawing, and the workpiece W is cut at the laser-irradiated portion. . Also, there are two types of processing routes in the vector mode. Route 1: A figure composed of continuous line segments, the line segments are connected from the beginning to the end like a single stroke (see FIG. 9). Route 2: A figure composed of a plurality of intermittent line segments, and there is a gap between each figure that does not emit laser light (see FIG. 10).

Among them, the processed figure of route 1 (see FIG. 9) is continuously laser processed, and the laser output signal continues to be output from the starting point to the end point of the laser. Route 2 requires turning off the laser output signal after processing each line segment (object), moving to the start point of the next line segment (object), and then turning on the laser output signal again. That is, even in the same vector mode, the laser output signal of Route 1 may be a signal with a long duration. It can be obtained only after the entire laser processing is completed. Instead, route 2 (see FIG. 10) processes each line segment (object) because it is necessary to turn off the laser output signal once and move a certain distance after processing each line segment (object). The laser non-output period T1 can be acquired each time.

In vector mode processing, when processing a root 1 type figure, the laser output signal is not turned off during processing, so the laser non-output period T1 does not occur during processing. When processing a Route 2 type figure, the laser output signal is turned off when moving between line segments (objects), and a short laser non-output period T1 for flame detection can be obtained.

Details of specific determination of this embodiment in the combustion determination unit 80 in raster mode and vector mode will be described below.

Since the non-metallic workpiece W may ignite and burn due to laser irradiation, the combustion determination unit 80 can continuously detect the flame detection signal Q even if the laser output is stopped by the laser output signal. , determine that ignition or combustion may have occurred. As a result, the combustion determination unit 80 compares the laser output signal and the flame detection signal Q during laser processing, and first detects the flame detection signal Q detected when the laser is not output by the laser output signal. In the laser non-output period T1 (raster mode: period during which laser is not output in each line and line break period, vector mode: movement period between line segments (objects)) during which the laser is not output by the laser output signal during laser processing, When a flame is detected by the flame detection signal Q, the combustion judgment unit 80 judges that there is a possibility that the device is ignited and burns, and uses a counter to detect flame in this situation. Accumulate the signal Q. The combustion determination unit 80 accumulates the laser non-output period T1, and when the accumulated time of the multiple laser non-output periods T1 reaches the accumulated detection period TM (for example, 1000 ms), the total number of detections of the flame detection signal Q is accumulated. If the constant CM is not reached, the timer and counter are reset to continue detecting the flame detection signal Q in units of the accumulated detection period TM. When the cumulative time of the non-output period T1 of multiple lasers has not reached the cumulative detection period TM or has reached the cumulative detection period TM, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount CM, the device is ignited and burned. It is determined that there is an abnormality, and at least one of the warning section 81 and the display section 82 is controlled to issue a warning. That is, since the non-metal workpiece W is likely to ignite and burn due to laser irradiation, first, as the detection period, the period during which the laser is not output by the laser output signal is targeted for ignition detection. As shown in FIG. 11, assuming that the length of each laser non-output period T1 is 100 ms, if one flame detection signal Q is detected during one laser non-output period T1, the tenth laser non-output period Before T1 ends, the total number of detected flame detection signals Q reaches a cumulative predetermined amount of 10, and the combustion determination section 80 determines that the apparatus is in an abnormal state of ignition and combustion.

Next, the situation in which sparks temporarily remain on the surface of the workpiece W immediately after the laser output signal is turned off will be described.

Immediately after the laser output signal is turned off, sparks remain on the surface of the workpiece W for a moment (for example, 0 to 3 ms) due to the laser irradiation, and the ultraviolet rays contained in the sparks are detected by the ultraviolet phototube sensor 71 to generate a flame detection signal Q. occurs. When the flame detection signals Q detected during the period are accumulated, there is a possibility that the combustion determination section 80 will erroneously detect the remaining momentary spark as ignited combustion. Therefore, it is necessary to ignore the flame detection signal Q generated during a certain period immediately after the laser output signal is turned off. Here, a fixed period after the laser output signal is turned off is defined as a detection exclusion period TE, and clocking and counting are not performed during the detection exclusion period TE. In this embodiment, the detection exclusion period TE is set to 10 ms.

The vector mode laser output signal has a relatively long duration of the laser output signal, as shown in FIG. If the workpiece W is a material that easily generates sparks, as long as the output of the laser output signal continues, the ultraviolet phototube sensor 71 continues to detect the flame due to the ultraviolet light contained in the sparks and generate a sensor discharge signal. The flame detector 70 continuously detects the flame detection signal Q while the signal continues. Sparks remain on the surface of the workpiece W for a moment when the laser output signal is turned off. For example, in FIG. 12, since the number of sensor discharge signals reached exactly three in the period from the generation of the second flame detection signal Q until the spark disappeared, the sensor drive board 72 outputs the flame detection signal Q. 1 occurs. At this time, since the laser output signal is already in a non-output state, accumulation of the third flame detection signal Q is likely to cause an erroneous determination.

As for the laser output signal in the raster mode, for example, as shown in FIG. 13, the duration of the laser output signal may be shorter than the sampling period of 25 ms of the sensor drive board 72, so the sensor discharge signal of all the laser output signals is detected. There is no guarantee that it will. For example, as shown in FIG. 13, when the third sensor discharge signal is generated, the laser output signal is already in a non-output state. It is caused by However, at this time, the sensor drive board 72 generates one flame detection signal Q because the number of sensor discharge signals is exactly three. At this time, since the laser output signal is already in a non-output state, accumulation of the third flame detection signal Q is likely to cause an erroneous determination.

For example, in raster mode (engraving mode), the following determination methods are provided. A detection exclusion period TE, which will be described later, is set to 10 ms, a cumulative detection period TM is set to 1000 ms, and a cumulative predetermined amount CM of flame detection signals Q necessary for determining ignition combustion is set to 10.
1. As indicated by (A) in FIG. 14, when laser output is performed for one line of data without gaps, the flame detection signal Q is detected aiming at the laser non-output period at the time of line feed.
2. As shown by (B) in FIG. 14, when there is a gap of 10 ms or less in one row of data, the gaps in the row are not accumulated because the detection exclusion period of 10 ms, which will be described later, is effective. The flame detection signal is detected aiming at the laser non-output period at the time of line feed.
3. As shown by (C) in FIG. 14, if there is a gap of 10 ms or more in one row of data, the flame detection signal Q in the first 10 ms detection exclusion period TE is ignored, and ignition detection starts after 10 ms has passed. do. Specifically, as shown in (C) of FIG. 14, when the gap is 20 ms, the remaining 10 ms excluding the detection exclusion period TE of 10 ms from 20 ms is the detection period (hereinafter referred to as "effective detection period TA"). In the example shown in Fig. 14C, the effective detection period TA accumulated within a row is 55 ms.
Table 1 summarizes the above.

１行のデータに隙間がない場合とある場合との検知のタイミング

Timing of detection when there are no gaps in one row of data and when there are gaps

That is, in the raster mode, not only the line feed period but also the gaps in each line where laser output is not performed are to be detected. When the cumulative time of the effective detection period TA reaches the cumulative detection period TM, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount CM, the device is not ignited and is in a normal state. Then, the timer and counter are reset to continue detecting the flame detection signal Q in units of the accumulated detection period TM. When the cumulative time of the effective detection period TA has not reached the cumulative detection period TM or has reached the cumulative detection period TM, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount CM, the device ignites and burns. , and performs control to issue a warning in at least one of the warning section 81 and the display section 82 .

As shown in FIGS. 15 and 16, the combustion determination unit 80 determines that after a laser non-output period T1 in which laser is not output by a laser output signal during laser processing and after a detection exclusion period TE has passed (for example, 10 ms has passed). After: If a flame is detected by the flame detection signal Q during the effective detection period TA of the "detection exclusion period" shown in FIGS. A counter is used to accumulate the flame detection signal Q in this situation. Among them, the effective detection period TA in the vector mode is the period from the end of each detection exclusion period TE to the start of the next laser output signal in FIG. The flame detection signal Q detected after the period TE ends is accumulated. The effective detection period TA in the raster mode is the period from the end of each detection exclusion period TE to the start of the next laser output signal in FIG. In the example of FIG. 16, the flame detection signals Q detected after the third detection exclusion period TE has ended are accumulated.

Then, the combustion determination section 80 accumulates the flame detection signal Q during the effective detection period TA. When the cumulative time of the effective detection period TA reaches the cumulative detection period TM, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount CM, it is determined that the device is in a normal state without firing. Then, the timer and counter are reset to continue detecting the flame detection signal Q in units of the accumulated detection period TM. When the cumulative time of the effective detection period TA has not reached the cumulative detection period TM or has reached the cumulative detection period TM, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount CM, the device ignites and burns. , and performs control to issue a warning in at least one of the warning section 81 and the display section 82 .

Next, a method for determining ignition combustion when a single laser output signal is longer than a predetermined period will be described.

In the vector mode as shown in FIG. 9, since there is no line feed operation, it is not possible to periodically obtain the effective detection period TA of a stable length. For example, in Route 1 of FIG. 9, since the laser non-output period T1 does not occur from the start to the end of the entire machining, the effective detection period TA for detecting the flame detection signal Q during machining cannot be obtained. Therefore, even if ignition combustion occurs during processing, the flame cannot be detected. For example, in route 2 in FIG. 10, the laser non-output period T1 for detecting the flame detection signal Q can be acquired each time processing of one line segment (object) is completed, but in raster mode, it is fixed for each line. The number and duration of the laser no-output periods T1 obtained in the vector mode are very unstable when compared with the length of the line feed period obtained.

In the detection method described so far, in the vector mode, the flame detection signal Q generated while the laser is being output by the laser output signal is ignored, and the laser non-output period T1 occurs during which the laser is not being output by the laser output signal. Then, the ignition detection is started only after the detection exclusion period TE has passed. In this detection method, when the workpiece W ignites and burns in the vector mode, the effective detection period TA cannot be obtained even after a long time has passed since the ignition occurred, and an abnormal state of ignition and combustion is detected. May not be detected quickly.

In order to solve the problem of special situations in vector mode as described above, not only the period when the laser is not output by the laser output signal is the detection target, but also the period when the laser is output by the laser output signal. It is necessary to create and invent a mechanism to detect ignition and combustion.

However, in the vector mode, the processing speed is slower than in the raster mode, and the laser energy irradiates the workpiece W for a long time. Become. In addition, since the ultraviolet phototube sensor 71 cannot distinguish whether the detected ultraviolet light is due to sparks or ignition/combustion, the above timing/counting method can detect flames generated by both sparks and generation/combustion. When the signal Q is accumulated, an erroneous determination that a spark is erroneously detected as ignition/combustion is likely to occur.

In order to distinguish between sparks and ignition/combustion, the following hypotheses are made. When sparks are generated in the workpiece W during laser irradiation, the flame detection signal Q also stops immediately because the sparks have the property of quickly extinguishing. When the workpiece W ignites and burns, the burning flame continues to spread and the flame detection signal Q continues to be generated. Using the above characteristics, if the flame detection signal Q is continuously detected while the laser is being output by the laser output signal, a detection method can be created that determines that the signal is due to ignition or combustion. .

However, accumulating the periods during which the laser is output with a plurality of laser output signals in the same manner as in the above method results in accumulating not only the laser output signal in the vector mode but also the laser output signal in the raster mode. The duration of the laser output signal in the raster mode is very short, and if the workpiece W is a material that is likely to generate sparks, the combustion determination unit 80 outputs the laser with the multiple laser output signals in the raster mode. If the detected flame detection signal Q is accumulated, it becomes impossible to distinguish whether the detected flame detection signal Q is due to sparks or due to ignition/combustion. Therefore, when the firing detection is performed for the period during which the laser is output by the laser output signal, it should not be accumulated for the period during which the laser is output by the multiple laser output signals. That is, the ignition detection period when the laser is output by the laser output signal is limited to the laser signal. According to the method described above, the quantity of the flame detection signal Q detected during the period in which the laser is output by the laser output signal in the raster mode is reset at the same time when the laser output signal is interrupted. It is limited to the laser non-output period T1 in which the laser is not output by the output signal.

As described above, the combustion determination unit 80 determines that the device ignites and burns when flame detection is detected by the flame detection signal Q during the period in which the laser is being output by the single laser output signal during laser processing. A counter is used to accumulate the flame detection signals Q generated in that situation. When the output period of the laser output by the single laser output signal reaches a predetermined period T3 (e.g., 5000 ms), the total number of detected flame detection signals Q has not reached a cumulative predetermined amount C3 (e.g., 40). , the timer and counter are reset, and ignition detection for the flame detection signal Q is continued until the laser output signal is terminated in units of a predetermined period T3. If the duration of the laser output signal has not reached or has reached the predetermined period T3, and the total number of detections of the flame detection signal Q has reached the cumulative predetermined amount C3, the device is in an abnormal state of ignition and combustion. It is possible to summarize a detection method for performing control to issue a warning in at least one of the warning section 81 and the display section 82 .

Although the theoretical saturation detection amount of the flame detection signal Q in this embodiment is 13 per second, the saturation detection amount per second slightly fluctuates during actual detection. As a result of actual verification, it was found that 10 flame detection signals Q arrive on average per second when combustion continues. Below, the actual saturation detection value is defined as 10 per second. Therefore, in the above detection method, when ignition/combustion occurs while the laser is being output by a single laser output signal, the ignition takes 3.07 seconds theoretically, and about 4 seconds in actual situations. It is possible to determine the abnormal state of burning.

With this setting, even if the maximum detection state of the flame detection signal Q (one at 75 ms intervals) continues, after 3.07 seconds have passed, it will ignite and burn. Short laser output signals (most laser output signals in raster mode) are excluded and are not subject to fire detection.

With this setting, it is possible to solve the problem that the effective sensing period TA of a regular and stable length cannot be obtained in the vector mode. In the vector mode, the flame detection signal Q can be detected not only by using the laser non-output period T1, but also by utilizing the period during which the laser is output by a single laser output signal, so that ignition and combustion can be accurately performed. can be determined.

The above-described detection method covers specific detection methods in raster mode and vector mode, and also considers removal of static electricity noise. However, in laser processing, it is necessary to consider the characteristics of the workpiece W as well.

In the laser processing of the non-metal workpiece W, there are special materials that are likely to generate violent sparks, such as tiles, ceramics, glass, crystals, granite, ceramics, and semiconductor crystals. When the workpiece W is irradiated with the laser, very bright sparks are generated. Since the ultraviolet phototube sensor 71 cannot distinguish whether the flame detection signal Q is due to sparks or ignition/combustion, the flame detection signal Q generated by both sparks and generation/combustion is detected by a normal timing/counting method. Accumulation of , erroneous detection of spark ignition/combustion is likely to occur.

For example, when performing laser processing on a ceramic plate. In the raster mode, during the laser output period T1 during which the laser is output according to the laser output signal, the ceramic plate of the workpiece W is irradiated with the laser, and violent sparks are generated. When entering the laser non-output period T1 in which the laser is not output by the laser output signal, the spark immediately disappears. According to the above detection method, since the period during which the laser is output by the single laser output signal in the raster mode is short (the duration of the single laser output signal is shorter than the predetermined period T3), the laser is output by the laser output signal. The flame detection signal Q is immediately reset when the signal ends. At the same time, the laser non-output period T1 during which the laser is not output by the laser output signal in the raster mode is to be detected. Since the spark disappears immediately after the laser non-output period T1 in which the laser is not output by the laser output signal, the flame is not detected by the flame detection signal Q during the effective detection period TA after the detection exclusion period TE has passed. No misjudgment occurs. Therefore, in the raster mode, even if laser processing is performed on a ceramic plate, for example, there is no false alarm.

However, in the vector mode, the duration of the single laser output signal may reach the predetermined period T3, and during the laser output period when the single laser output signal is lasing, the ceramic plate of the workpiece W , intense sparks are generated by laser irradiation. Therefore, when the detection method described so far is used, the combustion determination unit 80 will erroneously detect the flame detection signal Q due to sparks from the ceramic plate as being due to ignition/flame. When a flame is detected by the flame detection signal Q while the laser is being output by a single laser output signal, when the total number of detected flame detection signals Q reaches a cumulative predetermined amount C3, the combustion determination unit 80 detects sparks. erroneously detected as ignition/combustion.

In order to solve the problem of misjudgment caused by the above-mentioned special circumstances, it is necessary to improve the ignition/combustion detection method during the laser output period with a single laser output signal. Since the erroneous determination as described above occurs only when processing a material that easily generates sparks in the vector mode, it is necessary to improve the ignition detection method in the vector mode.

In the vector mode, when a single laser output signal is applied to a workpiece W, such as a ceramic plate, where sparks are likely to occur, the workpiece W instantaneously generates intense sparks. This feature can be used to perform material determination during the first predetermined period of laser output with a single laser output signal. In this embodiment, the initial predetermined period during which the laser is output by a single laser output signal is defined as the material determination period T2. When the flame detection signal Q is detected immediately after the laser is output by the laser output signal, and the total number of detected flame detection signals Q reaches a cumulative predetermined amount C2 (for example: 3) during the material determination period T2 (for example, 2000 ms). , the workpiece W is determined to be a material that easily generates sparks. Therefore, the flame detection signal Q detected over the entire period of laser output by the laser output signal cannot be used as a basis for determining ignition or combustion, and it is necessary to stop counting and measuring the flame detection signal Q of the laser output signal. There is

That is, the following detection methods can be summarized. As shown in FIG. 17, the combustion determination unit 80 detects flame by the flame detection signal Q during the first material determination period T2 after the state of outputting laser with a single laser output signal during laser processing. In this case, it is determined that there is a possibility that the workpiece W is a material that easily generates sparks, and a counter is used to accumulate the flame detection signal Q in this situation. When the duration of the laser output signal reaches the material determination period T2, if the total number of detected flame detection signals Q reaches a cumulative predetermined amount C2, the workpiece W is determined to be a material that easily generates sparks. , the firing is not detected during the entire period of the laser output signal. As shown in FIG. 18, when the duration of the laser output signal reaches the material determination period T2, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount C2, the workpiece W is sparked. is determined to be a material that is unlikely to generate, and ignition detection for the single laser output signal is performed starting from the end of the material determination period T2.

If the flame detection signal Q detects a flame while the laser output signal continues, the combustion determination unit 80 may determine that the device is ignited and is in an abnormal state of combustion. A counter is used to accumulate the flame detection signals Q generated in this state. When the continuous output period of the laser output by the single laser output signal reaches the predetermined period T3, if the total number of detections of the flame detection signal Q does not reach the cumulative predetermined amount C3, the timer and counter are reset, and the timer and the counter are reset for the predetermined period. Ignition detection for the flame detection signal Q is continued until the laser output by the laser output signal ends in units of T3. When the continuous output period of the laser output by the laser output signal has not reached or reached the predetermined period T3, and the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount C3, the device ignites and burns. It is determined that there is an abnormal state, and control is performed to issue a warning in at least one of the warning section 81 and the display section 82 .

By improving the detection method of a single laser output signal like an anomaly, it is possible to avoid erroneous judgment that sparks are erroneously detected as ignition combustion when laser processing is performed on a workpiece W that easily generates sparks. be able to.

At the same time, in this embodiment, assuming that the components of the workpiece W are uniformly distributed, the total number of flame detection signals Q detected within the material determination period T2 (for example: 2000 ms) is a cumulative predetermined amount. If C2 (for example, 3) is not reached, the total number of detected flame detection signals Q due to flames generated by the material after the start of ignition detection reaches a predetermined cumulative amount C3 (for example, , 40). Therefore, it is considered that the detection method described above does not cause an erroneous determination that a spark is erroneously detected as ignition combustion, and it can be proved that this detection method is effective.

In the raster mode, the firing detection method for line feeds and gaps between lines is that the flame detection signal Q is detected only during the laser non-output period T1 during which no laser is output by the laser output signal. The detection method for the laser output period does not affect the detection process for the laser non-output period T1. Therefore, it can be proved that the detection method described above is effective even in an arbitrary processing state of laser processing.

Next, a situation will be described in which the operator changes the laser output power while the laser is being output with a single laser output signal during laser processing.

In the method for detecting a single laser output signal described above, when the duration of the laser output signal reaches the material determination period T2 after the laser is output by the single laser output signal, the flame detection signal Q is detected. If the total number of detections does not reach the cumulative predetermined amount C2, the combustion determination unit 80 determines that the workpiece W is a material that is unlikely to generate sparks, and sets the end time of the material determination period T2 as the start time. 1. Perform firing detection for the laser output signal. Then, the combustion determination section 80 accumulates all the flame detection signals Q detected.

When the workpiece W is a ceramic plate or other material that easily generates sparks, and the laser output power initially set by the operator is extremely weak, the total number of flame detection signals Q detected during the material determination period T2 is accumulated. If the predetermined amount C2 has not been reached, the combustion determination unit 80 determines that the workpiece W is a material that does not easily generate sparks, and performs ignition detection for the laser output signal from the end of the material determination period T2. . However, when the worker raises the laser output power after this and bright sparks are generated on the surface of the workpiece W, the flame detection signal Q detected while the laser is being output by the laser output signal is accumulated, and combustion occurs. The judging section 80 is likely to make an erroneous judgment that the spark is erroneously detected as ignition/combustion.

When the laser is output by the single laser output signal, the timer and counter are reset to solve the problem caused by the operator changing the laser output power, and the material is judged again from the start of the material judgment period T2. method can be solved.

For example, when the operator changes the laser output power during a predetermined period T3, the counter and timer are reset, and the time when the laser output power is changed is used as the starting point for re-detection from the material determination period T2. When the duration of the laser output signal reaches the material determination period T2, if the total number of detected flame detection signals Q reaches a cumulative predetermined amount C2, the workpiece W is determined to be a material that easily generates sparks. , the firing is not detected during the entire period of the laser output signal. When the duration of the laser output signal reaches the material determination period T2, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount C2, the workpiece W is determined to be a material that is unlikely to generate sparks. Firing detection for the single laser output signal is performed starting from the end of the material determination period T2.

If the flame detection signal Q detects a flame while the laser output signal continues, the combustion determination unit 80 may determine that the device is ignited and is in an abnormal state of combustion. A counter is used to accumulate the flame detection signals Q generated in this state. When the continuous output period of the laser output by the single laser output signal reaches the predetermined period T3, if the total number of detections of the flame detection signal Q does not reach the cumulative predetermined amount C3, the timer and counter are reset, and the timer and the counter are reset for the predetermined period. Ignition detection for the flame detection signal Q is continued until the laser output signal ends in units of T3. When the continuous output period of the laser output by the laser output signal has not reached or reached the predetermined period T3, and the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount C3, the device ignites and burns. It is determined that there is an abnormal state, and at least one of the warning section 81 and the display section 82 is controlled to issue a warning.

By the above method, it is possible to avoid an erroneous determination that sparks are erroneously detected as ignition combustion due to the operator changing the laser output power while the laser is being output by a single laser output signal.

The above content was an analysis of the problems surrounding the vector mode. When analyzing for the raster mode, it is assumed that the flame was detected by the flame detection signal Q during the period when the laser was output by the laser output signal, and the total detection of the flame detection signal Q detected during the material determination period T2. When the number reaches the cumulative predetermined amount C2, the flame detection signals Q detected over the entire period of laser output by the laser output signal are not accumulated. Further, when the operator changes the laser output power after entering the predetermined period T3, the combustion determination unit 80 resets the counter and the timer, and the time when the laser output power changes is set as the starting time, and the workpiece is processed from the material determination period T2. It is determined whether or not the object W is likely to generate sparks. Based on the above assumptions, it can be seen that an erroneous determination that a spark is erroneously detected as ignition combustion does not occur in both the vector mode and the raster mode. Therefore, it can be seen that this detection method is effective.

Next, ignition detection after completion of laser processing will be described.
The laser processing machine 1 starts detection of ignition when an operator starts laser processing, and ends detection of ignition when laser processing ends. Assuming that the workpiece W ignites during laser processing, in both raster mode and vector mode, there is a specific detection method for detecting ignition/combustion when the laser is output or not output by the laser output signal. There is However, if the workpiece W ignites/combusts at the last moment of laser processing, the combustion determination unit 80 cannot detect the ignition/combustion if the ignition detection ends at the end of processing. Therefore, it is necessary to perform ignition detection for a while after the laser processing is completed.

When the laser processing machine changes from the laser processing state to the standby state or the stop state, the ignition detection after the laser processing is performed with the time when the operating state changed as the starting point. When flame is detected by the flame detection signal Q after the start of detection, the combustion determination unit 80 determines that there is a possibility that the device is ignited and is burning, and uses a counter to detect the flame in the situation. of flame detection signals Q are accumulated. When the detection time reaches the post-machining detection period T4 (for example, 40000 ms), if the total number of detected flame detection signals Q has not reached a cumulative predetermined amount C4 (for example, 50), the workpiece W ignites. It judges that it is not, and terminates the ignition detection. When the detection time has not reached or has reached the post-machining detection period T4, if the total number of detections of the flame detection signal Q has reached a cumulative predetermined amount C4, the apparatus is determined to be in an abnormal state of ignition and combustion. It judges and controls to issue a warning in at least one of the warning section 81 and the display section 82 .

If the above detection method is used, when the workpiece W ignites and burns after the end of the laser processing, the actual saturation detection amount (10 pieces/second) will detect an abnormality that ignites and burns in about 5 seconds. state can be determined. When only sparks are generated in the workpiece W after laser processing is completed, the sparks disappear immediately, and when the detection time reaches the post-processing detection period T4, the total number of detected flame detection signals Q reaches a cumulative predetermined amount C4. do not do. Based on the above assumptions, it can be seen that the detection method described above is effective.

Next, the open/closed state of the top lid 132 (access panel) of the laser processing machine 1 will be described.
It can be seen from FIG. 4 that the laser processing machine 1 can block all ultraviolet rays from the outside when the top cover 132 (access panel) is closed. Therefore, when the top cover 132 (access panel) is closed, the ignition detection of the laser processing machine is not affected by the external environment.

However, when the operator opens the upper lid 132 (access panel) of the laser processing machine 1 and operates it, the ultraviolet rays from the outside of the processing machine directly reach the flame detector 70 inside the laser processing machine. For example, things that easily generate ultraviolet rays include cigarettes, sunlight, and the flame of a lighter.

Therefore, when the upper lid 132 (access panel) of the laser processing machine 1 is open, the combustion determination unit 80 does not detect ignition.

According to the above-described embodiment, the following effects can be exhibited.
In this embodiment, the combustion determination unit 80 compares the laser output signal and the flame detection signal Q, detects the flame detection signal Q when the laser is not output by the laser output signal, and determines the laser output. During laser non-output period T1 (raster mode: period during which laser is not output in each line and line feed period, vector mode: movement period between line segments (objects)) when laser is not output by a signal, flame detection signal Q When a flame is detected, the combustion judgment section 80 judges that there is a possibility of an abnormality in which the device ignites and burns, and accumulates the flame detection signal Q in this situation. When the cumulative time of the non-output period T1 of the laser reaches the cumulative detection period TM, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount CM, the timer and counter are reset and the cumulative detection period TM is reached. The flame detection signal Q continues to be detected in units of . When the cumulative time of the laser non-output period T1 has not reached or has reached the cumulative detection period TM, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount CM, an abnormal state of ignition and combustion. We judge that it is.

With this configuration, even if the raster mode (engraving mode) and vector mode (cutting mode) have different laser processing methods and laser output signals, it is possible to detect ignition combustion (fire) by aiming at the timing when the laser is not output. It is possible to correctly detect flames, and to prevent erroneous detection of sparks as flames caused by ignition. Therefore, malfunction of the fire extinguishing system for extinguishing the generated flame can be prevented. As a result, it is possible to realize the laser processing machine 1 that can be operated in an unmanned state.

In addition, since it is possible to detect flames in a very short time after the outbreak of flames, it is necessary to take measures to prevent fires from escalating within a short period of time in the initial stage when fires do not grow from the outbreak of flames. becomes possible. As a result, failure due to ignition combustion in the laser processing machine 1 can be minimized. In addition, the detection system can detect ignition at the fastest speed, so after the fire is extinguished, there is no need to return it to the factory for repair, and it can be used again. At the same time, the ignition detection device is not disposable and can be used repeatedly for ignition detection.

Further, in the present embodiment, the combustion determination unit 80 compares the laser output signal and the flame detection signal Q, detects the flame detection signal Q when the laser output signal is not outputting the laser, and Laser non-output period T1 in which laser is not output by laser output signal during laser processing (raster mode: period in which laser is not output in each line and line feed period, vector mode: period of movement between line segments (objects)) If a flame is detected by the flame detection signal Q during the effective detection period TA after the detection exclusion period TE has passed after the time, it is determined that there is a possibility that the device is ignited and burned. , and a counter is used to accumulate the flame detection signal Q in that situation. When the cumulative time of the effective detection period TA reaches the cumulative detection period TM, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount CM, the timer and counter are reset and the cumulative detection period TM is used as a unit. , the flame detection signal Q continues to be detected. When the cumulative time of the effective detection period TA has not reached the cumulative detection period TM or has reached the cumulative detection period TM, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount CM, the device ignites and burns. It is judged that it is in the state of With this configuration, after entering the non-laser output period T1 in which no laser is output according to the laser output signal, the combustion determination part 80 can avoid erroneous determination that the residual spark is erroneously detected as ignition combustion.

Further, in the present embodiment, the combustion determination unit 80 causes the apparatus to ignite when flame detection is detected by the flame detection signal Q during the period in which the laser is being output by the single laser output signal during laser processing. A counter is utilized to accumulate the flame detection signal Q generated in that situation. When the output period of the laser output by the single laser output signal reaches the predetermined period T3, if the total number of detections of the flame detection signal Q has not reached the accumulated predetermined amount C3, the timer and the counter are reset, and the timer and the counter are reset for the predetermined period T3. The ignition detection for the flame detection signal Q is continued until the laser output signal ends. If the duration of the laser output signal has not reached or has reached the predetermined period T3, and the total number of detections of the flame detection signal Q has reached the cumulative predetermined amount C3, the device is in an abnormal state of ignition and combustion. I judge. With this configuration, even if one laser cutting line segment (object) is long, for example, even if it takes 10 minutes or more from the start to the end of laser irradiation, there is no need to wait until the laser irradiation is finished, and the laser can be cut during laser processing. A flame that causes a fire can be detected by the output signal while the laser is being output, and the detection period can be secured without missing the timing of ignition detection.

Further, in the present embodiment, the combustion determination unit 80 detects flame by the flame detection signal Q during the first material determination period T2 after the state of outputting the laser with a single laser output signal during laser processing. In this case, it is determined that there is a possibility that the workpiece W is a material that easily generates sparks, and a counter is used to accumulate the flame detection signal Q in this situation. When the duration of the laser output signal reaches the material determination period T2, if the total number of detected flame detection signals Q reaches a cumulative predetermined amount C2, the workpiece W is determined to be a material that easily generates sparks. , the firing is not detected during the entire period of the laser output signal. When the duration of the laser output signal reaches the material determination period T2, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount C2, the workpiece W is determined to be a material that is unlikely to generate sparks. Firing detection for the single laser output signal is performed starting from the end of the material determination period T2. If the flame detection signal Q detects a flame while the laser output signal continues, the combustion determination unit 80 determines that there is a possibility that the device is ignited and is in an abnormal state. A counter is used to accumulate the flame detection signals Q generated in this state. When the continuous output period of the laser output by the single laser output signal reaches the predetermined period T3, if the total number of detections of the flame detection signal Q does not reach the cumulative predetermined amount C3, the timer and counter are reset, and the timer and the counter are reset for the predetermined period. Ignition detection for the flame detection signal Q is continued until the laser output by the laser output signal ends in units of T3. When the continuous output period of the laser output by the laser output signal has not reached or reached the predetermined period T3, and the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount C3, the device ignites and burns. It is judged to be in an abnormal state. With this configuration, when laser processing is performed on a workpiece W containing a material that easily generates sparks, such as silicon or alumina, the material determination period T2 is used to prevent an erroneous determination that sparks are erroneously detected as ignition combustion. can be avoided.

Further, in this embodiment, when the laser processing machine changes from the laser processing state to the standby state or the stopped state, the ignition detection after the laser processing is performed with the time point at which the operating state changes as the starting point. When flame is detected by the flame detection signal Q after the start of detection, the combustion determination unit 80 determines that there is a possibility that the device is ignited and is burning, and uses a counter to detect the flame in the situation. of flame detection signals Q are accumulated. When the detection time reaches the post-machining detection period T4, if the total number of detected flame detection signals Q does not reach the cumulative predetermined amount C4, it is determined that the workpiece W is not ignited, and the ignition detection is terminated. . When the detection time has not reached or has reached the post-machining detection period T4, if the total number of detections of the flame detection signal Q has reached a cumulative predetermined amount C4, the apparatus is determined to be in an abnormal state of ignition and combustion. to decide. With this configuration, it is possible to effectively avoid the problem of not being able to detect the ignition when the workpiece W ignites at the moment the laser processing ends.

Further, in this embodiment, a warning unit and a display unit are provided, and when the combustion determination unit determines that an abnormal state of ignition and combustion occurs, at least one of the warning unit 81 and the display unit 82 is displayed. Control to warn in . With this configuration, the warning from the warning unit 81 and the display unit 82 makes it possible for the operator who processes the workpiece W to quickly know the abnormal state of ignition and combustion.

In this embodiment, the flame detection unit 70 includes an ultraviolet phototube sensor 71 and a sensor drive board 72, and the flame detection unit 70 is sealed by a sealed metal box 701 and a front window 702 made of glass. The front window 702 is housed inside a structured housing, and is made of quartz glass that transmits ultraviolet rays with a wavelength of 180 nm to 260 nm. With this configuration, the flame detection section 70 is housed in an airtight space by the sealed metal box and the front window, making it possible to prevent the flame detection section 70 from being exposed to dust.

Further, in the present embodiment, in the processing space 102 inside the apparatus main body 10 as a housing in which the flame detection unit 70 is accommodated, the flame detection unit 70 is located above the workpiece W in the vertical direction, and It is arranged below the workpiece facing portion 33 that irradiates a laser at a predetermined position of the workpiece W, is arranged behind the workpiece W in the front-rear direction, and is located behind the workpiece W in the left-right direction. It is arranged in the central position of W. With this configuration, the flame detection unit 70 can obtain the maximum flame detection field of view, and ultraviolet rays caused by the flame generated by the workpiece W are blocked by parts such as the front and rear rails 31 or the left and right rails 32, making it impossible to detect the flame. can be prevented.

Further, in this embodiment, the combustion determination section 80 as the combustion determination section is incorporated in the main control board that controls the oscillation of the laser oscillator. With this configuration, the combustion determination unit 80 having the laser output signal acquisition unit acquires the laser output signal directly from the main control board, so it can make a determination by comparing the flame detection signal Q and the laser output signal.

Further, in the present embodiment, an intake port is formed in the front portion of the device main body 10 as a housing in which the flame detection section 70 is housed, and an exhaust port is formed in the rear portion of the housing. And the exhaust port is provided with an ultraviolet shielding wall for shielding ultraviolet rays. With this configuration, it is possible to construct a structure in which ultraviolet rays coming toward the apparatus main body 10 from all angles outside the apparatus main body 10 cannot directly reach the flame detection section 70 inside the laser processing machine.

Further, in the present embodiment, the housing in which the flame detection unit 70 is housed has the device main body 10 as a box-shaped main body and the upper lid 132 as a window. It is composed of a resin plate that transmits and blocks ultraviolet rays with a wavelength of 180 nm to 260 nm. With this configuration, ultraviolet rays coming toward the apparatus main body 10 from the outside of the apparatus main body 10 cannot directly reach the flame detection section 70 inside the laser processing machine 1 through the upper lid 132, and the laser processing machine 1 can The operator who performs the processing of (1) can visually recognize how the workpiece W is being processed with visible light.

Further, in the present embodiment, the direction of the airflow entering the inlet is set so that the airflow entering the apparatus main body flows along the inside of the apparatus main body, and an annular airflow is formed inside the laser processing machine 1, By guiding the smoke and dust generated from the workpiece W away from the flame detection section, the smoke does not affect the detection sensitivity of the flame sensor, and the flame detection section 70 can correctly detect the ultraviolet rays caused by the flame. .

Further, in this embodiment, the housing in which the flame detection unit 70 is housed has the device main body 10 as a box-shaped main body and the upper lid 132 as a window. When 132 is open, it is in a judgment pause state in which it is not judged whether the state is normal or abnormal. With this configuration, when the top cover 132 is open, the flame detector 70 detects ultraviolet rays (burning cigarettes, sunlight, flames outside the processing machine, etc.) coming toward the apparatus main body 10 from outside the apparatus main body 10. As a result, it is possible to prevent the combustion determining unit 80 from erroneously determining that there is an abnormal state of ignition and combustion. Therefore, when the upper cover 132 is open during maintenance/repair of the laser processing machine 1, the combustion determination unit 80 can prevent erroneous determination that the laser beam is in an abnormal state of ignition and combustion. becomes possible.

The present invention is not limited to the embodiments described above, and can be implemented in various forms within the scope of the claims. For example, the configuration of each part of the laser processing machine 1, the configuration of each part of the ignition detection device (laser output signal acquisition unit, flame detection signal acquisition unit, combustion determination unit), etc. are the same as those of the laser processing machine 1 in this embodiment. The configuration, the configuration of each part of the flame detection unit 70, and the configuration of each part of the combustion determination unit 80 are not limited.

Moreover, although the flame detection unit 70 has the ultraviolet phototube sensor 71, it is not limited to this configuration. Other types of sensors may also be used for flame detection.

Although the present invention and embodiments have been described above, the description is not limited to the content of the description, and the description in the explanatory diagrams is merely one of the embodiments of the present invention, and the actual configuration is not limited to this. Therefore, if a person skilled in the art is enlightened by this and uncreatively designs a structure and embodiment similar to the present technical method on the premise that it does not deviate from the gist of the present invention, the protection scope of the present invention shall be included in

Q: Flame detection signal TA: Effective detection period TE: Detection exclusion period T2: Material determination period

Claims (14)

a laser output signal acquisition step of acquiring a laser output signal of a laser oscillator during laser processing;
a flame detection step of acquiring a flame detection signal Q obtained by detecting a flame generated by laser irradiation to the workpiece W;
comparing the laser output signal and the flame detection signal Q, and detecting a flame detected during the duration of a single laser output signal and during the duration of the laser output signal when the laser is output according to the laser output signal; Based on the total number of detections of the signal Q, it is determined whether or not the device is in an abnormal state of ignition and combustion, and when the laser output signal is not outputting the laser, the flame detected during the cumulative detection period is detected. an ignition combustion determination step of determining whether or not the device is in an abnormal state of ignition and combustion based on the total number of detected signals Q. In the ignition combustion determination step,
If the flame is detected by the flame detection signal Q during the laser non-output period T1 in which the laser is not output by the laser output signal, it is determined that there is a possibility that the device is ignited and burned. , a counter is used to accumulate the flame detection signal Q in that situation,
When the cumulative time of the laser non-output period T1 reaches the cumulative detection period TM, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount CM, the device is not ignited and is in a normal state. Then, the timer and counter are reset to continue detecting the flame detection signal Q in units of the accumulated detection period TM,
When the cumulative time of the laser non-output period T1 has not reached the cumulative detection period TM or has reached the cumulative detection period TM, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount CM, the device ignites and burns. 2. The ignition detection method according to claim 1, wherein it is determined that the state of In the ignition combustion determination step,
When a flame is detected by the flame detection signal Q during the effective detection period TA after the detection exclusion period TE has passed since the laser non-output period T1 during which the laser is not output by the laser output signal, the device ignites. and determine that there is a possibility of burning abnormality, accumulate the flame detection signal Q in that situation using a counter,
When the cumulative time of the effective detection period TA reaches the cumulative detection period TM, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount CM, it is determined that the device is in a normal state without firing. continue to detect the flame detection signal Q in units of the accumulated detection period TM by resetting the timer and the counter;
When the cumulative time of the effective detection period TA has not reached the cumulative detection period TM or has reached the cumulative detection period TM, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount CM, the device ignites and burns. 3. The ignition detection method according to claim 2, wherein it is determined that the state of In the ignition combustion determination step, when the laser is output by the laser output signal, the duration of the single laser output signal is shorter than the material determination period T2, and the flame is detected by the flame detection signal Q. 4. The ignition detection method according to any one of claims 1 to 3, wherein it is determined that the device is in a normal state without ignition, and all flame detection signals Q during the entire laser output signal period are not accumulated. When the duration of the single laser output signal reaches the material determination period T2, if the flame is detected by the flame detection signal Q during the material determination period T2, the workpiece W may easily generate sparks. and accumulate the flame detection signal Q using a counter,
When the duration of the laser output signal reaches the material determination period T2, if the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount C2, the workpiece W is determined to be a spark-prone material. , without performing the flame detection process during the entire period of the laser output signal,
When the duration of the laser output signal reaches the material determination period T2, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount C2, the workpiece W is considered to be a material that is unlikely to generate sparks. 5. The firing detection method according to claim 4, wherein the firing detection process for the single laser output signal is started at the end of the material determination period T2. With the end of the material determination period T2 as the start time, ignition detection is performed for the single laser output signal,
If a flame is detected by the flame detection signal Q while the laser output signal continues, it is determined that there is a possibility that the device is ignited and burned, and the counter is used. and accumulate the flame detection signal Q in that situation,
When the output period of the laser output by the single laser output signal reaches the predetermined period T3, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount C3, the apparatus is in a normal state without firing. , resetting the timer and the counter to continue firing detection for the laser output signal in units of a predetermined period T3,
When the laser output signal continues and the duration of the laser output signal does not reach or reaches the predetermined period T3, and the total number of detections of the flame detection signal Q reaches the cumulative predetermined amount C3, the device ignites and burns. 6. The ignition detection method according to claim 5, further comprising a flame detection step of determining that an abnormal state exists. 7. The ignition detection method according to claim 6, wherein when the laser output power is changed within the predetermined period T3, the counter and the timer are reset and the ignition combustion determination step is restarted from the time when the laser output power is changed. When the laser processing machine changes from the laser processing state to the standby state or the stop state, the ignition detection after laser processing is performed with the time when the operating state changed as the starting point,
If flame is detected by the flame detection signal Q after the start of detection, the device determines that there is a possibility of ignition and combustion, and uses a counter to detect the flame detection signal Q in that situation. accumulate,
When the detection time reaches the post-machining detection period T4, if the total number of detected flame detection signals Q has not reached the cumulative predetermined amount C4, it is determined that the workpiece W is not ignited, and the ignition detection is terminated. ,
When the detection time has not reached or has reached the post-machining detection period T4, if the total number of detections of the flame detection signal Q has reached a cumulative predetermined amount C4, the apparatus is determined to be in an abnormal state of ignition and combustion. The ignition detection method according to any one of claims 1 to 3, wherein the determination is made. a laser output signal acquisition unit that acquires a laser output signal of the laser oscillator during laser processing;
a flame detection unit that detects a flame generated by irradiating the workpiece with the laser;
a flame detection signal acquisition unit that detects a flame by the flame detection unit and acquires a flame detection signal Q;
comparing the laser output signal and the flame detection signal Q, and detecting a flame during the duration of a single laser output signal and during the output period of the laser output signal when the laser is output according to the laser output signal; Based on the total detection number of the detection signal Q, it is determined whether the device is in an abnormal state of ignition and combustion, and when the laser output signal is not outputting the laser, the flame detected during the cumulative detection period is detected. The ignition detection method according to any one of claims 1 to 8, further comprising a combustion judgment unit for judging whether or not the device is in an abnormal state of ignition and combustion based on the total number of detected signals Q. A fire detection device that uses An intake port is formed in the front part of the housing that houses the flame detection unit, and an exhaust port is formed in the rear surface of the housing, and a light shielding wall that blocks ultraviolet rays is provided in the intake port and the exhaust port,
The light-shielding wall prevents external ultraviolet light from reaching the processing space in the laser processing machine even if it is irradiated from any angle, and the positions of the air inlet and the air outlet are higher than the surface of the workpiece W, and the workpiece W The direction of the airflow entering the intake port is set so that the smoke and dust generated from the W are quickly exhausted by the airflow, and the airflow entering the main body of the device flows along the inside of the main body of the device. 10. The ignition detection device according to claim 9, wherein the flame detection unit forms a . The flame detection unit includes an ultraviolet phototube sensor and a sensor drive board,
The flame detection unit is housed in a case having a sealed structure with a sealed metal box and a glass front window,
11. The ignition detection device according to claim 10, wherein the front window is made of quartz glass that transmits ultraviolet rays having a wavelength of 180 nm to 260 nm. The sensor driving substrate is provided with a DC/DC converter, and the output voltage of the DC/DC converter is applied to the anode and cathode of the ultraviolet phototube sensor via a step-up transformer,
The sensor driving board is provided with a signal processing circuit including a gate timer and a counter, the output side of the ultraviolet phototube sensor is connected to the input side of the gate timer and counter, and the output side of the gate timer is connected to the input side of the counter. 12. The ignition detection device according to claim 11 , wherein an output circuit is provided on the output side of the counter, and the output circuit amplifies the pulse signal output from the counter to a required time width and outputs it as the flame detection signal Q. . A warning unit and a display unit are provided, and when the combustion determination unit determines that there is an abnormal state of ignition and combustion, at least one of the warning unit and the display unit issues an alarm. The ignition detection device according to any one of 1. The housing housing the flame detection unit includes a device main body and an upper lid,
The upper cover is made of a resin plate that transmits visible light and blocks ultraviolet rays with a wavelength of 180 nm to 260 nm, and when the upper cover is open, the combustion determination unit does not detect ignition. The ignition detection device according to .

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