JP6519211B2 - Laser cutting apparatus and laser cutting method - Google Patents

Description

  The present invention relates to a laser cutting apparatus that irradiates high-power laser beams and cuts metal, and more particularly to a laser cutting apparatus and a laser cutting method that cuts metal by a remote device.

  When laser cutting is performed at a factory etc., it is common practice to install a light shielding plate, a water tank, etc. in front of the processing point of the object to be cut so that the object to be protected located behind the object is not cut. is there.

  However, in places where workers do not enter, such as in a nuclear facility, it may not be possible to install a light shield or a water tank behind the object to be cut. In this case, the worker visually recognizes the object to be cut with a camera or the like. However, it has been necessary to adjust the irradiation direction and output of the laser beam so as not to damage other protected objects by remote control.

  Also, conventionally, a protected area centered on the processing head end of the remotely operated laser cutting apparatus is set, and it is confirmed whether or not a structure other than the object to be cut exists in the protected area, and the protected area is In the case where there is a structure other than the object to be cut, there are cases in which the movement of the processing head is restricted, or the restriction of the cutting process is performed.

  However, the conventional protection area is spherical around the tip of the processing head, directions other than the irradiation direction of the laser beam are set as the protection area, and the size of the protection area is constant regardless of the laser beam output. Even if there is no risk that the protective object will be damaged by the laser beam, it is considered that the structure has interfered with the protected area, so it was not a practical system.

  It is noted in U.S. Pat. No. 5,075,095 that an hourglass-shaped nominally dangerous area is provided around the laser beam centered on the focal point of the laser beam, and the safety device waits for the intensity of the laser beam when the hand is within the nominally dangerous area. An arrangement to reduce to the level is disclosed.

JP 2007-61910 A

  SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a laser cutting apparatus and a laser cutting method for improving the working efficiency of a laser cutting process by remote control.

  According to the present invention, a laser processing head for irradiating a laser beam to an object to be cut, a laser oscillation control unit for controlling irradiation and stop of the laser beam, and an output value, and position information for acquiring position information of the laser processing head An acquisition unit, a protection region setting unit which is concentric with the optical axis of the laser beam and sets a conical protection region including the laser beam, a storage unit in which position information of a protection target is stored, and the protection The detection unit detects an intrusion of the protection object into the area, and an operation control unit, and the operation control unit outputs the detection signal to the laser oscillation control unit when the detection signal is output from the detection unit. The present invention relates to a laser cutting device for stopping the irradiation of the laser beam from the processing head.

  Further, the present invention relates to a laser cutting apparatus in which the protected area is set to be larger than the irradiation range of the laser beam.

  Further, the present invention relates to the laser cutting apparatus in which the protection area is set to be scaled based on increase and decrease of the output value of the laser beam.

  Further, according to the present invention, the setting conditions of the protected area include the spread angle of the laser beam, the output value of the laser beam, and the moving speed of the laser processing head, and the protected area is the laser beam. A laser cutting apparatus in which the output value of the laser beam and the moving speed of the laser processing head are set such that the rising temperature ΔT of the protection object is less than a predetermined value when the protection object is directly irradiated. Pertaining to

  Further, according to the present invention, the setting condition of the protected area includes the spread angle of the laser beam and the distance from the tip of the laser processing head, and the protected area directly corresponds to the protected object. The present invention relates to a laser cutting apparatus in which the distance from the tip of the laser processing head is set such that the temperature increase ΔT of the object to be protected is less than a predetermined value when it is irradiated.

  Furthermore, the present invention is directed to a laser cutting method for irradiating a laser beam of a predetermined spread angle to cut an object to be cut, which comprises a conical protective area including the laser beam concentrically with the optical axis of the laser beam. The present invention relates to a laser cutting method in which the irradiation with the laser beam is stopped when the object to be protected enters the protected area.

  According to the present invention, a laser processing head for irradiating a laser beam to a cutting object, a laser oscillation control unit for controlling irradiation and stop of the laser beam, and an output value, and position information of the laser processing head are acquired. A position information acquisition unit, a protection region setting unit concentric with the optical axis of the laser beam, and setting a conical protection region including the laser beam, and a storage unit in which position information of a protection target is stored; A detection unit that detects the entry of the protection object into the protection area, and an arithmetic control unit are provided, and the arithmetic control unit outputs the detection signal to the laser oscillation control unit when the detection unit outputs the detection signal. Since the irradiation of the laser beam from the laser processing head is stopped, the cutting process is interrupted by the protection target located at a position unrelated to the laser cutting, such as the side or proximal side of the laser processing head. It is no, the movable range of the laser processing head is widened, it is possible to improve the work efficiency.

  Further, according to the present invention, there is provided a laser cutting method for irradiating a laser beam of a predetermined spread angle to cut an object to be cut, wherein a conical protective region including the laser beam concentrically with the optical axis of the laser beam. Is set, and the irradiation of the laser beam is stopped when the object to be protected enters the protected area, so that the cutting process may be interrupted by the object to be protected located at a place unrelated to the laser cutting. In addition, the movable range of the laser processing head is expanded, and the excellent effect that the working efficiency can be improved is exhibited.

It is a schematic block diagram which shows the laser cutting device which concerns on the Example of this invention. It is an explanatory view showing a protection field concerning an example of the present invention. It is an explanatory view showing cutting processing by a laser cutting device concerning an example of the present invention.

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

  First, referring to FIG. 1, a laser cutting apparatus 1 according to an embodiment of the present invention will be described.

  The laser cutting apparatus 1 includes a laser processing head 3, a drive unit 4, a laser oscillation control unit 5, a position information acquisition unit 6, a protected area setting unit 7, a storage unit 8, a detection unit 9, and calculation. A control unit 11, a display unit 12, an input unit 13, and an operation unit 14 are provided.

  The laser processing head 3 irradiates the object to be cut with a high power laser beam 2 to cut the object to be cut, and can be moved in three axial directions by a moving mechanism such as a crane (not shown), or is required It is provided rotatably in the direction of. The drive unit 4 has, for example, a motor as an actuator for each axis. The motor of each axis cooperates to move or rotate in a three-dimensional direction through the moving mechanism.

  The laser oscillation control unit 5 controls irradiation and stop of the laser beam 2 emitted from the laser processing head 3 and controls an output value of the laser beam 2 and the like, and the detection unit described later The irradiation of the laser beam 2 is stopped on the basis of the detection signal from 9.

  The position information acquisition unit 6 has, for example, a sensor that detects the drive amount of the drive unit 4, and on a three-dimensional reference coordinate, which will be described later, based on the drive amount of the drive unit 4 detected by the sensor. It is possible to acquire the position of the laser processing head 3 with respect to a known position, for example, the origin.

  The protective area setting unit 7 sets the laser processing head based on the spread angle of the laser beam 2, the output value of the laser beam 2 input from the operation unit 14, the material of the object to be protected, the moving speed, and the like. A conical protection area 15 (see FIG. 2) which spreads in the irradiation direction of the laser beam 2 from the tip end of 3 is set. The axial center of the protective area 15 is concentric with the optical axis of the laser beam 2 and has a spread angle θ '(see FIG. 2).

  Further, the storage unit 8 stores, for example, a three-dimensional coordinate system having an initial position of the laser processing head 3 as an origin, and coordinate data on the three-dimensional coordinate system of various structures to be protected. Are stored, and the position information of the laser processing head 3 acquired by the position information acquisition unit 6 is stored.

  The detection unit 9 stores the position information of the laser processing head 3 detected by the position information acquisition unit 6, the protected area 15 set by the protected area setting unit 7, and the storage unit 8. An intrusion of the protection object into the protection area 15 is detected based on three-dimensional coordinate data of the protection object, and a detection signal is output.

  The display unit 12 displays an image of a camera for photographing the laser processing head 3, an object to be cut, etc., the protected area 15 formed at the tip of the laser processing head 3, and the like. Further, the input unit 13 is used to set the protective area 15 such as an output value of the laser beam 2 irradiated from the laser processing head 3, a moving speed of the laser processing head 3, a material of an object to be protected, It is possible to input various information. Furthermore, the operation unit 14 is, for example, a keyboard, a touch panel or the like, and outputs a drive instruction to the drive unit 4 to operate the laser processing head 3.

  Next, referring to FIG. 2, a method of setting the protection area 15 will be described. In FIG. 2, La represents the height of the protective area 15, r represents the radius of the bottom of the protective area 15, r ′ represents the beam diameter of the laser beam 2, and θ represents the protective area 15. Represents the spread angle of the laser beam 2. Θ ′ is determined by an optical system incorporated in the laser processing head 3 and is known.

  In the present embodiment, the material of the object to be protected is SUS (stainless steel). The height La of the protective area 15 is set such that the surface temperature of the object to be protected does not reach 300 ° C. when the object to be protected is irradiated for 10 seconds with the laser beam 2 having a predetermined output value. . Also, the radius r of the protective area 15 is larger than the beam diameter r 'of the laser beam 2 determined by the spread angle θ' of the optical system incorporated in the laser processing head 3, eg, radius r ' It is set to be 1.2 times of. The relationship between the irradiation time of the laser beam 2, the surface temperature of the object to be protected, the radius r of the protective area 15 and the beam diameter r 'of the laser beam 2 is limited to the above values. For example, according to the material etc. of a protection subject, it sets suitably.

  Here, the temperature rise ΔT of the surface of the object to be protected can be expressed by the following equation.

ΔT = (2H / K) (κt / π) ^1/2

  In the above equation, H represents a heat flux, K represents a thermal conductivity of SUS (W / m · K), κ represents a thermal diffusion coefficient of SUS, and t represents an elapsed time (s). The elapsed time t is the irradiation time of the laser beam 2 to the object to be protected per unit area, and can be obtained from the beam diameter r 'of the laser beam 2 and the moving speed of the laser processing head 3. The moving speed of the laser processing head 3 may be constant or may be set for each process. Further, from the viewpoint of safety, it is desirable to set the elapsed time t longer than the actual elapsed time in setting the protection area 15.

  The heat flux H and the thermal diffusion coefficient κ can be expressed by the following equations.

  H = I (1-RS)

  κ = K / ρC

In the above equation, I represents the beam intensity (W / m ² ) obtained by dividing the output value of the laser beam 2 by the cross-sectional area of the laser beam 2, RS represents the surface reflectivity of SUS, and ρ represents The density (kg / m ³ ) of SUS is shown, and C shows the specific heat (kJ / kg · K) of SUS. The beam intensity I of the laser beam 2 is a non-uniform distribution in which the intensity is concentrated at the center of the beam, but in the present embodiment, the beam intensity I will be described as being uniform in the irradiation surface.

  Further, among the above formulas, the thermal conductivity K, the density ρ, the specific heat C, the surface reflectance RS, that is, the thermal diffusion coefficient κ and the surface reflectance RS are known values determined by the material of the object to be protected The rising temperature ΔT is a known value obtained by subtracting the current surface temperature of the object to be protected from the set temperature set to less than 300 ° C.

  Therefore, the amount of heat input to the object to be protected such that the temperature rise is ΔT is determined by the beam intensity I and the elapsed time t, so the output value of the laser beam 2 or the laser via the input unit 13 The beam diameter r ′ of the laser beam 2 is determined by inputting the output value of the light beam 2 and the moving speed of the laser processing head 3.

  By determining the beam diameter r 'of the laser beam 2, the radius r of the protective area 15 is determined. Also, the height La of the protective region 15 is determined from the relationship of tan θ ′ / 2 = r ′ / La, based on the beam diameter r ′ and the known spread angle θ ′. Further, the spread angle θ of the protective area 15 is determined from the relationship of tan θ / 2 = r / La by the height La and the radius r of the protective area 15, and the size of the protective area 15 is determined.

  The relationship between the output value of the laser beam 2 and the beam diameter r 'of the laser beam 2 is associated in advance to form a database, and when the output of the laser beam 2 is input, the laser is used using the database. The beam diameter r 'of the light beam 2 may be determined. Processing time can be shortened by using a database.

  Further, by reducing the output of the laser beam 2, the cross-sectional area of the bottom of the protective region 15 can be reduced, and as shown in FIG. 3, the output of the laser beam 2 is increased or decreased. The protection area 15 can be scaled.

  The object to be protected 16 (see FIG. 3) is based on the known spread angle θ ′ of the laser beam 2 and the distance La from the tip of the laser processing head 3 so that the beam intensity I becomes equal to or less than a predetermined value. You may set the said protection area | region 15 of the magnitude | size which does not enter.

  Next, the operation of the laser cutting device 1 will be described with reference to FIG.

  First, by setting the output value of the laser beam 2 from the input unit 13, the protective area setting unit 7 sets the spread angle of the laser beam 2, the output value of the laser beam 2, the protection object 16. The conical protection area 15 which spreads in the irradiation direction of the laser beam 2 from the tip of the laser processing head 3 is set based on the material and the like of the above.

  After setting the protection area 15, the operator refers to the camera image or the like displayed on the display unit 12 and moves the laser processing head 3 to a position where the object 17 to be cut can be cut through the operation unit 14 Let

  At this time, positional information of the laser processing head 3 is acquired in real time by the positional information acquisition unit 6 and stored in the storage unit 8.

  When the irradiation instruction of the laser beam 2 is output from the laser oscillation control unit 5, the laser beam 2 is irradiated from the laser processing head 3, and the cutting of the object to be cut 17 is performed.

  During the cutting process, the position of the laser processing head 3 is calculated in real time, the position of the protection area 15 is calculated, and position information of the protection area 15 formed at the tip of the laser processing head 3 by the detection unit 9 And the position information of the protection object 16 are compared in real time, and when the intrusion of the protection object 16 into the protection area 15 is detected, a detection signal is output from the detection unit 9 Be done.

  When a detection signal is output from the detection unit 9, the calculation control unit 11 causes the laser oscillation control unit 5 to output a stop instruction of the laser beam 2, and the laser beam 2 emitted from the laser processing head 3. Is stopped.

  In this state, when the cutting process of the object to be cut 17 is continued, the output value of the laser beam 2 is decreased via the input unit 13, and the object to be protected 16 enters the protective area 15. The protective area 15 is reduced so as to form a protective area 15 '. Accordingly, the moving speed of the laser processing head 3 is decreased via the input unit 13 to increase the elapsed time t, that is, the irradiation time of the laser beam 2 to the object 17 to be cut is increased. The heat input necessary for cutting can be secured, and the cutting process of the object to be cut 17 can be continued.

  As described above, in the present embodiment, the shape of the protection area 15 for preventing the erroneous cutting of the protection object 16 is directed from the tip of the laser processing head 3 in the irradiation direction of the laser beam 2. It is in the form of an expanding cone and is limited to a range substantially including the laser beam 2.

  Therefore, the cutting process is not interrupted by the protection target 16 located at a position unrelated to the laser cutting, such as the side or proximal side of the laser processing head 3, and the movement of the laser processing head 3 is not performed. The possible range can be expanded, the range and frequency of cutting stop can be reduced, and the working efficiency can be improved.

  Further, since the protective area 15 is set based on the spread angle θ ′ of the optical system incorporated in the laser processing head 3 and the beam diameter r ′ of the laser beam 2, the tip side of the laser processing head 3 is Even in this case, it is possible to prevent the cutting process from being interrupted by the protection target 16 located at a place regardless of the cutting process.

  Further, the radius r of the bottom surface of the protective area 15 is set to be larger than the beam diameter r ′ of the laser beam 2, and the protective area 15 is larger than the irradiation range of the actual laser beam 2. When the object to be protected 16 intrudes into the protected area 15, the laser beam 2 can be prevented from being irradiated to the object to be protected 16.

  When setting the protection area 15, the elapsed time t is made longer than the actual time. That is, by estimating the irradiation time of the laser beam 2 to the object to be protected longer, even if the laser beam 2 is irradiated to the object to be protected longer than the setting due to some problems, Erroneous cutting can be suppressed and safety can be improved.

  Furthermore, since the protection area 15 can be expanded or shrunk by increasing or decreasing the output value of the laser beam 2, the protection target is protected even when the protection target 16 can not move, such as fixed piping. The cutting process can be continued without intruding the object 16 into the protected area 15.

DESCRIPTION OF SYMBOLS 1 laser cutting device 2 laser beam 3 laser processing head 4 drive part 5 laser oscillation control part 6 position information acquisition part 7 protected area setting part 8 storage part 9 detection part 11 arithmetic control part 15 protected area 16 protected object 17 cut object

Claims (6)

  A laser processing head for irradiating a laser beam to the object to be cut, a laser oscillation control unit for controlling the irradiation and stop of the laser beam, and an output value, and a position information acquisition unit for acquiring position information of the laser processing head; A protection area setting unit which is concentric with the optical axis of the laser beam and sets a conical protection area including the laser beam, a storage unit in which position information of the object to be protected is stored, and the protection area A detection unit for detecting intrusion of a protection target and an arithmetic control unit are provided, and the arithmetic control unit outputs the detection signal to the laser oscillation control unit from the laser processing head when the detection signal is output from the detection unit. A laser cutting apparatus characterized by stopping irradiation of the laser beam.   The laser cutting device according to claim 1, wherein the protective area is set to be larger than the irradiation range of the laser beam.   The laser cutting device according to claim 1 or 2, wherein the protected area is set to be scaled based on increase or decrease of the output value of the laser beam.   The setting conditions of the protected area include the spread angle of the laser beam, the output value of the laser beam, and the moving speed of the laser processing head, and in the protected area, the laser beam is directly the protected object The laser beam output value and the moving speed of the laser processing head are set such that the temperature T of the object to be protected is less than a predetermined value when the laser beam is irradiated to The laser cutting device according to any one of the above.   The setting condition of the protected area includes the spread angle of the laser beam and the distance from the tip of the laser processing head, and the protected area is the case where the object to be protected is directly irradiated with the laser beam. The laser cutting apparatus according to any one of claims 1 to 3, wherein the distance from the tip of the laser processing head is set such that the temperature increase ΔT of the object to be protected is less than a predetermined value. . A laser cutting method of irradiating a laser beam of a predetermined spread angle to cut a cutting object, setting a conical protective area including the laser beam concentrically with the optical axis of the laser beam, and operating in real time Intrusion of the protected object into the protected area is detected based on comparison between the position information of the protected area and the position information of the protected object acquired in advance, and the protected object intrudes into the protected area And stopping the irradiation of the laser beam when it occurs.

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