JP6311039B1 - Fire detecting method for laser beam machine and laser beam machine - Google Patents

Abstract

The present invention provides a fire occurrence detection method and a laser processing machine in a laser processing machine in which a laser processing head moves in the X, Y, and Z axis directions. A method for detecting a fire occurrence of a laser beam machine having a laser beam machining head that can be moved and positioned in the X, Y, and Z axis directions with respect to a plate-like workpiece supported on a work table or a pallet, A part of the machine body 3 in the laser processing machine 1 is provided with infrared cameras 19 and 21 as fire occurrence detection means, and the infrared camera 19 and 21 and the farthest laser processing position are partitioned into a plurality of detection areas. A fire occurs when the detection values of the infrared cameras 19 and 21 are corrected with a preset emissivity for each detection area and a temperature equal to or higher than a preset temperature is continuously detected for a preset time. Detect as. [Selection] Figure 5

Description

  The present invention relates to a fire detection method for a laser beam machine and a laser beam machine in which a laser beam machining head is relatively movable in an X axis direction, a Y axis direction, and a Z axis direction with respect to a workpiece located in a laser machining region. . More specifically, the present invention relates to a fire detection method for a laser beam machine and a laser beam machine having a function of detecting the occurrence of a fire around a laser beam machining head in a space above the laser beam machining area.

  For example, when laser processing of a plate-shaped workpiece is performed by a laser processing machine, for example, laser processing may occur due to a fire occurring on the protective sheet attached to the workpiece, spatter scattered from the laser processing position, or reflected laser light. A fire may occur in combustible materials around the head. Therefore, a sensor is arranged at a place where a fire is likely to occur in the laser processing machine, and the occurrence of the fire is detected by this sensor (see, for example, Patent Documents 1 and 2).

JP 11-123581 A JP 2004-202005 A

  The configuration described in Patent Document 1 is a configuration in which a machining head cover surrounding the laser machining head is provided so as to be movable up and down. When a fire occurs in the processing head cover, the fire is detected by a fire detection sensor provided in the processing head cover. The configuration described in Patent Document 2 is a configuration that detects the occurrence of a fire in a dust collector in a laser processing apparatus, and includes a fire detection sensor in a portion through which hot air passes when a fire occurs.

  The fire detection sensors in Patent Documents 1 and 2 are temperature sensors, and are configured to detect a fire as the occurrence of a fire when the temperature around the installation portion of the temperature sensor rises above a predetermined temperature due to the occurrence of a fire. Therefore, there is a large time difference from the beginning of the fire until the fire is detected. In other words, the occurrence of a fire is not detected until a fire occurs and the ambient temperature rises to some extent. That is, there is a problem that the occurrence of a fire is not detected until the fire has progressed to a certain size.

  By the way, by using a thermography (infrared camera), it is possible to detect a wide range of temperature changes including the periphery of the laser processing head and a temperature rise in the laser processing head. However, the infrared camera has a function of detecting infrared energy radiated from a fire occurrence site as a detection target, converting it into temperature data, and imaging an energy distribution. Therefore, in order to detect infrared energy, it is necessary to know the emissivity of the detection object.

  Here, in order to accurately measure the temperature of the detection target with the infrared camera, for example, 9 pixels (3 vertical pixels × 3 horizontal pixels) are required as the minimum unit of detection. That is, the infrared camera can detect that the temperature has risen only when the entire detection area of 3 × 3 pixels is covered with a hot spot (for example, 100 ° C. or more). Therefore, due to the viewing angle of the infrared camera, for example, if it is about 1 m away, it will be detected by a hot spot of 9.9 mm × 9.9 mm, but if it is about 5 m away, it is as wide as 52.5 mm × 52.5 mm If the area does not become a hot spot, it cannot be detected. That is, the size of the hot spot that can be detected varies depending on the distance from the infrared camera to the detection target.

  Therefore, when the distance increases, a large detection area including a fire occurrence point is detected. That is, if the distance is small, detection is possible even if the fire occurrence spot (hot spot) is narrow, but if the distance is large, not only the fire occurrence spot (hot spot) but also the surrounding area is incident on the infrared camera. Therefore, it cannot be immediately detected as a fire, and it is detected as a fire only after spreading around. Therefore, there may be a delay in detection due to a difference in distance from the infrared camera to the detection target, and it is desired to accurately detect the occurrence of a fire.

  The present invention has been made in view of the above-described problems, and includes a laser machining head that can be moved and positioned in the X, Y, and Z axis directions with respect to a plate-like workpiece supported on a work table or a pallet. A method for detecting the occurrence of a fire in a laser processing machine, comprising an infrared camera as a fire occurrence detection means in a part of the machine body of the laser processing machine, and a plurality of detection areas between the infrared camera and the farthest laser processing position. When the detection value of the infrared camera is corrected with a preset emissivity for each of the detection areas, and a temperature equal to or higher than a preset temperature is detected continuously for a preset time, a fire occurs. Detect as outbreak.

  In the fire detection method of the laser processing machine, the laser processing head is provided on a guide beam that can be moved and positioned in the X-axis direction, and can be moved and positioned in the Y-axis direction. A second infrared camera for detecting the occurrence of a fire around the laser processing head is provided on one end side, and when a temperature preset by the second infrared camera is detected continuously for a preset time, Detect as a fire outbreak.

  In the fire detection method of the laser beam machine, the set temperature is 100 ° C. and the set time is 10 seconds.

  A laser processing machine having a laser processing head that can be moved and positioned in the X, Y, and Z axis directions with respect to a plate-like work supported on a work table or a pallet, An infrared camera as a fire occurrence detection means for detecting the occurrence of fire on the upper side is provided in a part of the body of the laser processing machine, and for each of a plurality of detection areas between the infrared camera and the farthest laser processing position. A parameter table storing correction parameters for emissivity set in advance, and calculating means for correcting the detection value of the infrared camera with reference to the parameters stored in the parameter table;

  According to the present invention, the infrared camera provided in a part of the machine body of the laser processing machine and the farthest laser processing position are partitioned into a plurality of detection areas, and with a preset emissivity for each detection area. The occurrence of fire is detected by correcting the detection value of the infrared camera. Therefore, it is possible to quickly detect the occurrence of a fire around the laser processing area and the laser processing head in the laser processing machine.

It is perspective explanatory drawing which showed the whole structure of the laser processing machine roughly. In a laser beam machine, it is the perspective explanatory view which showed roughly the attachment position of the 1st, 2nd infrared camera, and arranging in the direction which the 1st, 2nd infrared camera crosses. . It is explanatory drawing which shows the whole structure of an infrared camera. It is explanatory drawing of the emissivity correct | amended corresponding to the distance from an infrared camera to a fire outbreak location. It is a functional block diagram of a fire occurrence detection device.

  Hereinafter, a laser processing machine according to an embodiment of the present invention will be described with reference to the drawings. The overall configuration of a laser processing machine is known. However, in order to facilitate understanding, the overall configuration of the laser processing machine will be schematically described.

  Referring to FIG. 1, a laser beam machine 1 according to an embodiment of the present invention includes a machine base 3. As shown schematically in FIG. 1, the overall configuration of the machine base 3 has a rectangular parallelepiped shape that is long in the X-axis direction. A work table 5 is provided on the upper surface of the machine base 3. The work table 5 is provided with dust collection chambers 7A to 7D that are divided into a plurality of portions in the X-axis direction. On the upper side of the dust collection chambers 7A to 7D, a pallet or a sword mountain table (not shown) supporting a plate-like workpiece is carried in and out in the X-axis direction.

  The upper side of the dust collection chambers 7A to 7D is a laser processing region for performing laser processing on the workpiece. In order to perform laser processing on the workpiece carried into the laser processing area, a laser processing head 9 is provided so as to be relatively movable in the X, Y, and Z axis directions. That is, guide rails 11 in the X-axis direction are provided on both sides of the machine base 3 in the Y-axis direction. The guide rail 11 supports both ends of a guide beam (carriage) 13 that is long in the Y-axis direction so as to be movable. The guide beam 13 is provided with a slider 15 that can be moved and positioned in the Y-axis direction. The slider 15 is provided with the laser processing head 9 so as to be movable up and down. That is, the laser processing head 9 is provided so as to be movable relative to the workpiece in the X, Y, and Z axis directions.

  Therefore, the guide beam 13 is moved and positioned in the X-axis direction under the control of a control device (not shown). Further, by moving and positioning the slider 15 in the Y-axis direction and positioning the laser processing head 9 up and down, laser processing can be performed on the workpiece positioned at the pass line height position in the laser processing region. .

  By the way, when laser processing of a workpiece is performed, the hose connected to the laser processing head 9 or its joint (not shown) is combustible by sputtering scattered from the laser processing position or reflected light of the laser beam from the laser processing position. Fire may occur on objects. Therefore, in the present embodiment, fire detection means is provided for detecting the occurrence of fire in the space above the upper surface of the workpiece in the laser processing region.

  That is, as schematically shown in FIG. 2, when the guide beam 13 is located at the reference position in the X-axis direction (position in the state shown in FIG. 2), the entire guide beam 13 is imaged. A first infrared camera 19 serving as a fire occurrence detection means is provided so as to be oriented in the horizontal direction (the direction in which the intensity of light incident on the camera at the horizontal angle is maximized). More specifically, the first infrared camera 19 is located at one end side in the X-axis direction away from the reference position in the X-axis direction of the guide beam 13 and away from the reference position in the Y-axis direction. It is provided at a position on one end side in the Y-axis direction (position shown in FIGS. 1 and 2). The first infrared camera 19 is provided at a height position that captures the periphery of the laser processing head 9 while avoiding spatter scattered from the laser processing position during laser processing of the workpiece.

  By the way, the viewing angle of the visual field 19A in the first infrared camera 19 is small as shown in FIG. 2 as a characteristic of the infrared camera 19, so that the guide beam 13 is far away from the infrared camera 19. The entire guide beam 13 can be imaged. However, when the guide beam 13 moves to one end side in the X-axis direction so as to be away from the reference position and the guide beam 13 comes close to the infrared camera 19, as is understood from FIG. That is, since the reference position side in the Y-axis direction deviates from the viewing angle 19A, it is difficult to capture the entire image. That is, when the guide beam 13 comes close to the infrared camera 19, the reference position side in the Y-axis direction of the guide beam 13 may deviate from the viewing angle due to the installation position of the infrared camera 19, resulting in a blind spot.

  Therefore, in the present embodiment, a second infrared camera 21 serving as a fire occurrence detection unit is provided in the horizontal direction on the reference side of the guide beam 13 in the Y-axis direction. The second infrared camera 21 images the periphery of the laser processing head 9 from one end side in the Y-axis direction. When the laser processing head 9 is raised after the laser processing is stopped, It is provided at a position higher than the highest rising position of the provided laser nozzle.

  As already understood, the periphery of the laser processing head 9 in the laser processing machine 1 is imaged from the X-axis direction by the first infrared camera 19 (the optical axis of the first infrared camera 19 is parallel to the X-axis direction). The image is taken from one end side in the Y-axis direction by the two infrared cameras 21 (the optical axis of the second infrared camera is parallel to the Y-axis direction). In this case, the first infrared camera 19 can image both sides of the laser machining head 9 in the Y-axis direction.

  However, when the guide beam 13 is close to the first infrared camera 19, the reference position side in the Y-axis direction of the guide beam 13 becomes a blind spot, and imaging becomes difficult. However, the second infrared camera 21 is provided on the reference position side (one end side) of the guide beam 13 in the Y-axis direction. Therefore, the blind spot of the first infrared camera 19 is covered by the second infrared camera 21. In the second infrared camera 21, the opposite side of the laser processing head 9 and the other end side in the Y-axis direction which is a shadow of the second infrared camera 21 (the Y axis on the side provided with the second infrared camera 21). The other side of the direction is a blind spot. However, this blind spot range is covered by the first infrared camera 19.

  As already understood, the periphery of the laser processing head 9 can be monitored by the first and second infrared cameras 19 and 21 without a blind spot. In other words, when a fire occurs around the laser processing head 9, the first and second infrared cameras 19, 21 can immediately detect the fire.

  By the way, as shown in FIG. 3, the first and second infrared cameras 19 and 21 are configured such that a rectangular parallelepiped housing 23 is provided with an infrared camera 25 and a visible light digital camera 27. The configurations of the infrared cameras 19 and 21 are already known, but have the following functions. That is, the infrared cameras 19 and 21 have a function of switching and displaying an infrared image from the infrared camera 25, a visible light image from the visible light digital camera 27, and an image obtained by combining both images on a monitor of a personal computer (not shown), for example. . In addition, when the detected temperature exceeds a preset temperature threshold, the alarm is automatically activated. Further, the display screen of the monitor is divided into a plurality of detection areas so as to easily detect a fire occurrence point.

  Therefore, the periphery of the laser processing head 9 is constantly monitored by the infrared cameras 19 and 21, and when it is detected that a certain area is at a temperature equal to or higher than a preset temperature threshold, it can be detected as a fire occurrence. Then, by looking at a plurality of detection areas, it is possible to immediately know the location of the fire.

  By the way, the laser processing position of the workpiece by the laser processing head 9 as well as the laser nozzle of the laser processing head 9 is extremely high during laser processing of the workpiece. Therefore, if the laser processing position and the laser nozzle are imaged by the infrared cameras 19 and 21 at the time of laser processing of the workpiece, a malfunction of fire detection is caused. Therefore, the display screen of the monitor is divided vertically and the upper screen is set as a detection area. In other words, the lower screen is set as a non-detection area.

  The screen partition means for partitioning the display screen of the monitor up and down is set using a mouse, for example. That is, for example, a visible light screen is displayed on the display screen of the monitor, and the laser processing head 9 is moved toward and away from the infrared cameras 19 and 21. Then, on the display screen, the position where the laser nozzle is displayed is marked with a mouse or the like. The display screen is vertically divided by entering a horizontal line at the marking position.

  Therefore, the laser nozzle is not displayed on the divided upper display screen. In other words, the upper screen divided vertically in the display screen is a detection area for detecting a fire, and is set to a screen that always excludes the laser processing position regardless of the movement position of the laser processing head 9. Therefore, the laser processing position of the workpiece and the temperature of the laser nozzle of the laser processing head 9 are not detected at the time of laser processing of the workpiece, and a malfunction of fire detection does not occur.

  Now, when a fire occurs around the laser processing head 9 during laser processing of the workpiece, the first and second infrared cameras 19 and 21 detect the fire. Incidentally, a flame-retardant material is used around the laser processing head 9 in the laser processing machine 1. Therefore, even if the spatter during laser processing adheres to the surrounding material, a fire does not immediately occur. In addition, fire extinguishing may occur due to self-extinguishing.

  By the way, when the machine oil (lubricating oil) used for moving the laser processing head 9, for example, for a ball screw adheres to, for example, a bellows or the like covering the ball screw, a bellows or the like made of a flame-retardant material is used. A fire may occur. In this case, combustion may continue without exhibiting a self-extinguishing function. Therefore, in order to detect that a fire has occurred around the laser processing head 9, when a temperature equal to or higher than a preset temperature is continuously detected for a preset time, it is detected as a fire occurrence.

  By the way, the flash point of machine oil is 106 ° C. to 270 ° C. Therefore, the preset temperature is preferably set to 100 ° C., for example. And in a flame-retardant material, it is desired that the fire duration is 10 seconds or less. Therefore, the preset time is preferably 10 seconds. Therefore, in this embodiment, when a preset temperature (for example, 100 ° C.) or higher is continuously detected for a preset time (for example, 10 seconds), a fire is detected.

  By the way, in the infrared cameras 19 and 21, a hot spot (100 ° C. or higher) is detected using, for example, 3 pixels × 3 pixels (9 pixels) as a minimum unit of detection in an area of 45 degrees horizontally and 35 degrees vertically. Therefore, a hot spot of about 9.9 mm × 9.9 mm or more can be detected at a position about 1 m away from the infrared cameras 19 and 21. And the hot spot of the position about 5 m away can be detected only when it becomes a hot spot of 52.5 mm × 52.5 mm or more.

  That is, as the distance from the infrared cameras 19 and 21 increases, the field of view of the nine pixels increases. Therefore, not only the infrared rays radiated from the combustion position where the fire has occurred but also the vicinity of the combustion position, for example, are incident on the infrared cameras 19 and 21. Therefore, even if the size of the combustion area is the same, in the case of a near field, even if the fire spread is small, it can be detected early. And if it is far away, it will be detected only after the spread of fire has increased and the danger has increased. Therefore, when the combustion area is the same, it is desirable to detect the occurrence of the same level of fire with no delay in detection even when the combustion position is close or far.

  Therefore, in each area of area 1 (X0 mm to X1500 mm), area 2 (X1500 mm to X3000 mm), area 3 (X3000 mm to X4000 mm), and area 4 (X4000 mm to X5300 mm) corresponding to the dust collection chambers 7A to 7D, an infrared camera is used. In order for 19 to detect 100 ° C., it was experimentally determined in advance how to correct the emissivity ε in each of the areas 1 to 4. Specifically, the infrared camera 19 is positioned at a distance of 2.0 m, 3.0 m, 4.0 m, and 5.0 m from the burned material, and the emissivity is sequentially decreased from 1 at each distance, and the measurement temperature is 100 ° C. As a result, the results as shown in FIG. 4 were obtained.

  That is, as understood from FIG. 4, when the emissivity ε is corrected to about 0.95 when the distance is 2 m, the infrared cameras 19 and 21 can detect the occurrence of fire as 100 ° C. or higher. Therefore, in order to perform the detection in the area 1 more quickly, the emissivity ε is corrected to 0.9 in advance. When the emissivity ε at a distance of 3 m is corrected to about 0.7, the infrared cameras 19 and 21 can detect the occurrence of a fire as 100 ° C. or higher. Therefore, it is desirable to correct the emissivity ε in the area 2 to 0.7 beforehand.

  Similarly, when the distance is 4 m, the occurrence of fire can be detected as 100 ° C. or higher by correcting the emissivity ε to about 0.35. Therefore, it is desirable to correct the emissivity ε in the area 3 to 0.3 in advance. In the case of a distance of 5 m, by correcting the emissivity ε to about 0.11, the occurrence of a fire can be detected as 100 ° C. or higher. Therefore, it is desirable to correct emissivity ε in area 4 to 0.1 in advance.

  By the way, the radiation and reflection of infrared rays from the laser processing head 9 and its periphery vary depending on the configuration of the laser processing machine. Therefore, it is desirable to determine the data indicating the relationship between the distance and the emissivity as shown in FIG. 4 for each model of the laser processing machine.

  The movement position of the guide beam 13 in the X-axis direction is, for example, a position command value for moving the guide beam 13 in the X-axis direction or a ball screw mechanism for moving the guide beam 13. It can be known by position detecting means such as a rotary encoder provided in the servo motor for the purpose. Therefore, the distance from the infrared camera 19 to the guide beam 13 can be calculated by the calculation means.

  Therefore, the fire occurrence detection device 29 for detecting the occurrence of fire in the laser beam machine 1 is configured as follows. That is, the fire occurrence detection device 29 is composed of, for example, a computer, and includes a parameter table 31 that stores the emissivity ε corrected in advance for each of the areas 1 to 4 as a correction parameter. The fire detection device 29 is connected to the infrared cameras 19 and 21 as fire detection means. Further, the fire detection device 29 is connected to position detection means 33 such as a rotary encoder for detecting the position of the guide beam 13 in the X-axis direction and the position of the laser machining head 9 in the Y-axis direction. is there.

  The fire occurrence detection device 29 is provided with calculation means 35. The calculation means 35 searches the parameter table 31 for the emissivity ε as a correction parameter corresponding to the detected position of the position detection value 33. And it has a function which calculates the temperature of a fire occurrence position based on the detected value of the said infrared cameras 19 and 21, and the said emissivity (epsilon).

  Further, the fire occurrence detection device 29 is provided with a comparison means 37. The comparison unit 37 has a function of comparing the set temperature (100 ° C.) stored in advance in the set value memory 39 with the detected temperature calculated by the calculation unit 35. The comparing means 37 has a function of comparing a set time (10 seconds) stored in the set value memory 39 in advance with a duration when the detected temperature calculated by the calculating means 35 is equal to or higher than the set temperature. It is what has.

  The comparison result by the comparison means 37 is displayed on the display means 41 connected to the fire occurrence detection device 29. As a result of comparison by the comparison means 37, when the detected temperature is 100 ° C. or higher and the duration is 10 seconds or longer, the alarm stop means 43 is notified of the occurrence of a fire. When the alarm stop means 43 is notified of the occurrence of a fire, the operation of the laser beam machine 1 is stopped via a control device (not shown) that controls the laser beam machine 1.

  Further, when a fire occurrence is detected as a result of the comparison by the comparison means 37, the notification means 45 is notified. Therefore, the notification means 45 notifies the worker of the occurrence of a fire, for example, by sound or light. Therefore, the worker performs fire extinguishing work.

  As can be understood from the above description, in this embodiment, the infrared cameras 19 and 21 are used as fire occurrence detection means for detecting the occurrence of a fire around the laser machining head 9 in the laser machining machine. And between the positions where the laser processing head 9 is farthest from the positions of the infrared cameras 19, 21 is partitioned in advance into a plurality of detection areas. The emissivity is corrected in advance for each detection area, and the detection of the fire is detected by correcting the detection values of the infrared cameras 19 and 21 with the precorrected emissivity.

  Therefore, even when the distance between the infrared cameras 19 and 21 and the location of the fire occurrence changes due to the movement of the laser processing head 9, the occurrence of the fire can be detected quickly and accurately.

DESCRIPTION OF SYMBOLS 1 Laser processing machine 3 Machine stand 5 Work table 7A-7D Dust collection chamber 9 Laser processing head 13 Guide beam 19 1st infrared camera 21 2nd infrared camera 25 Infrared camera 27 Visible light digital camera 29 Fire occurrence detection apparatus 31 Parameter Table 33 Position detection means 35 Calculation means 37 Comparison means 39 Set value memory 41 Display means 43 Alarm stop means 45 Notification means

Claims (4)

  A method for detecting fire occurrence of a laser beam machine having a laser beam machining head that can be moved and positioned in the X, Y, and Z axis directions with respect to a plate-like workpiece supported on a work table or a pallet. A part of the airframe is equipped with an infrared camera as a fire detection means, and is divided into a plurality of detection areas between the infrared camera and the farthest laser processing position, and radiation set in advance for each of the detection areas. Correcting the detection value of the infrared camera at a rate and detecting a fire occurrence when a temperature equal to or higher than a preset temperature is detected continuously for a preset time period .   2. The fire detection method for a laser beam machine according to claim 1, wherein the laser beam machining head is provided on a guide beam that can be moved and positioned in the X-axis direction, and can be moved and positioned in the Y-axis direction. A second infrared camera for detecting the occurrence of fire around the laser processing head is provided on one end side in the axial direction, and a preset temperature is continuously detected by the second infrared camera for a preset time. A method for detecting a fire of a laser beam machine, characterized in that it is detected as a fire occurrence.   3. The fire detection method for a laser beam machine according to claim 1, wherein the set temperature is 100 ° C. and the set time is 10 seconds.   A laser processing machine having a laser processing head that can be moved and positioned in the X, Y, and Z axis directions with respect to a plate-like work supported on a work table or a pallet, An infrared camera as a fire detection means for detecting the occurrence of a fire is provided in a part of the machine body of the laser processing machine, and preset for each of a plurality of detection areas between the infrared camera and the farthest laser processing position. A laser processing machine comprising: a parameter table storing a correction parameter for the emissivity obtained; and a calculation means for correcting the detection value of the infrared camera with reference to the parameter stored in the parameter table .

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