LASER IRRADIATION STATE DIAGNOSIS METHOD, LASER IRRADIATION STATE DIAGNOSIS PROGRAM, LASER IRRADIATION STATE DIAGNOSIS DEVICE, AND LASER IRRADIATION DEVICE

Abstract

Disclosed is a laser irradiation state diagnosing method which allows accurately diagnosing a laser irradiation state. When irradiating a laser beam so that an irradiation spot scans the surface of the irradiation object, acoustic information in vicinity of the irradiation spot is acquired. And based on characteristics of the acoustic information, such as an intensity of a component of a specific frequency band or a frequency band distribution, a state of peeling of the adhered substances existing on the surface of the irradiation object is determined.

Claims

1. A laser irradiation state diagnosis method, wherein when irradiating a laser beam so that an irradiation spot scans the surface of the irradiation object, acoustic information in vicinity of the irradiation spot is acquired, and based on characteristics of the acoustic information, a state of peeling of adhered substances existing on the surface of the irradiation object is determined, and wherein the acoustic information is acquired while changing the irradiation condition of the laser beam at a predetermined period, and a signal synchronized with the period is extracted.

2-10. (canceled)

11. A laser irradiation state diagnosis method, wherein when a laser beam is irradiated so that an irradiation spot scans a surface of an irradiation object along a predetermined pattern, acoustic information near the irradiation spot is acquired, and an inclination state of the irradiation head relative to the object is determined based on a periodic change in the acoustic information.

12. (canceled)

13. A laser irradiation state diagnosis program which causes a computer including an acoustic information acquisition unit for acquiring acoustic information to execute the laser irradiation state diagnosis method of claim 1.

14. A laser irradiation state diagnosis apparatus comprising: an acoustic information acquisition unit for acquiring acoustic information in the vicinity of an irradiation spot when irradiating a laser beam so that the irradiation spot scans a surface of an irradiation object; and a peeling state determining unit which determines a peeling state of adhered substances existing on a surface of the irradiation object based on characteristics of the sound information, wherein the acoustic information acquisition unit acquires the acoustic information while changing the irradiation condition of the laser beam at a predetermined period, and extracts a signal synchronized with the period.

15-25. (canceled)

26. A laser irradiation state diagnosis apparatus comprising an acoustic information acquisition unit for acquiring acoustic information in the vicinity of an irradiation spot when irradiating a laser beam so that the irradiation spot scans a surface of an irradiation object along a predetermined pattern, and an inclination state determination unit which determines an inclination state of an irradiation head to an irradiation object based on a periodic change of the sound information.

27. (canceled)

28. A laser irradiation state diagnosis apparatus according to claim 14, wherein the sound information acquisition unit includes a sound collection device provided in an irradiation head that emits the laser beam.

29. A laser irradiation state diagnosis apparatus according to claim 28, wherein a plurality of sound collection devices are provided, and the sound information acquisition unit generates the sound information based on outputs of the plurality of sound collection devices.

30. The laser irradiation state diagnosis apparatus according to claim 14, wherein the sound information acquisition unit includes a sound collection device that is disposed at a position spaced apart from the irradiation head.

31. The laser irradiation state diagnosis apparatus according to claim 14, wherein the sound information acquisition unit includes a sound collection device attached to the irradiation object.

32. A laser irradiation apparatus comprising: an irradiation head which emits a laser beam so that an irradiation spot scans a surface of an irradiation object, and a laser irradiation state diagnosis apparatus comprising: an acoustic information acquisition unit for acquiring acoustic information in the vicinity of an irradiation spot when irradiating a laser beam so that the irradiation spot scans a surface of an irradiation object; and a peeling state determining unit which determines a peeling state of adhered substances existing on a surface of the irradiation object based on characteristics of the sound information.

33. The laser irradiation apparatus according to claim 32, wherein the irradiation head includes a driving unit that drives a moving optical system that changes an optical path of the laser beam, and includes an abnormality determination unit that determines an abnormality of the driving unit based on the acoustic information.

34. The laser irradiation apparatus according to claim 32, wherein the irradiation head includes a driving unit that drives a moving optical system that changes an optical path of the laser beam, and a speed detection unit that detects a driving speed of the driving unit based on the acoustic information.

35. The laser irradiation apparatus according to claim 32, further comprising a sound recognition unit which recognizes a specific sound having predetermined characteristics from the acoustic information, and when the sound recognition unit recognizes the specific sound, the irradiation condition of the laser beam to be emitted is changed or the emission of the laser beam is stopped, and wherein the specific sound is a sound generated by a sound generator disposed around an operator or outside of an irradiated area of an irradiation object.

36. (canceled)

37. The laser irradiation apparatus according to claim 32, further comprising a sound recognition unit which recognizes a specific sound having predetermined characteristics from the acoustic information, and when the sound recognition unit recognizes the specific sound, the irradiation condition of the laser beam to be emitted is changed or the emission of the laser beam is stopped, and wherein the specific sound is a voice of an operator.

38. (canceled)

39. A laser irradiation state diagnosis program which causes a computer including an acoustic information acquisition unit for acquiring acoustic information to execute the laser irradiation state diagnosis method of claim 11.

40. A laser irradiation state diagnosis apparatus according to claim 26, wherein the sound information acquisition unit includes a sound collection device provided in an irradiation head that emits the laser beam.

41. The laser irradiation state diagnosis apparatus according to claim 26, wherein the sound information acquisition unit includes a sound collection device that is disposed at a position spaced apart from the irradiation head.

42. The laser irradiation state diagnosis apparatus according to claim 26, wherein the sound information acquisition unit includes a sound collection device attached to the irradiation object.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0082] FIG. 1 is a cross-sectional view of an irradiation head according to a first embodiment of a laser irradiation state diagnosis method and a laser irradiation apparatus to which the present invention is applied.

[0083] FIG. 2 is a block diagram schematically showing a system configuration of a laser irradiation apparatus according to a first embodiment.

[0084] FIG. 3 is a diagram showing an example of a frequency spectrum of acoustic information at the time of laser irradiation in the laser irradiation apparatus of the first embodiment.

[0085] FIG. 4 is a diagram showing an example of the intensity transition of sound information for each frequency band in the case of performing the rust removal work in the laser irradiation apparatus of the first embodiment.

[0086] FIG. 5 is a diagram showing an example of a spectrogram of acoustic information according to the focus and or defocus at the time of laser irradiation in the laser irradiation apparatus of the first embodiment.

[0087] FIG. 6 is a diagram showing an example of acoustic information expressed in a frequency domain at the time of inclination and non-inclination of an irradiation head in the laser irradiation apparatus according to the first embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The 1st Embodiment

[0088] Hereinafter, a laser irradiation state diagnosis method, a laser irradiation state diagnosis program, a laser irradiation state diagnosis apparatus, and a laser irradiation apparatus according to the 1st embodiment of the present invention will be described.

[0089] In the laser irradiation apparatus according to the 1st embodiment of the present invention for performing the laser irradiation state diagnosis method, there is provided an irradiation head 1 to which a beam of laser light supplied from a laser oscillator via a fiber is applied and the head irradiates the beam to the object O, and an irradiation point (beam spot BS) scans a surface of an irradiation object O along an arc scanning pattern, thus performing various cleaning processes such as removal of rust, peeling of an old paint coating and removal of adhered foreign substances. The irradiation object O is, for example, a metal structure of such as general steel, stainless steel, or an aluminum-based alloy, but is not particularly limited.

[0090] In the cleaning process, an irradiation spot (beam spot BS) is scanned on the surface of an irradiation object O by turning along a circular arc of a relatively large diameter of about 10 mm or more for example. By this laser processing (surface treatment), cleaning for various films such as rust, old paint coating (coating film to be peeled off), oxide film, and the like, and dust, soot etc. which have adhered to the surface of an irradiation object O are cleaned.

[0091] FIG. 1 is a cross-sectional view of an irradiation head in the laser irradiation apparatus according to the 1st embodiment.

[0092] The irradiation head 1 irradiates a laser beam R of continuous wave (CW) transmitted from a laser oscillator 110 (see FIG. 2) through a fiber (not shown) onto an irradiation object O.

[0093] While the irradiation head 1 is, for example, of a handy type which allows an operator to carry out the work, it is also possible to use the irradiation head 1 by attaching it to a robot which can move the irradiation head 1 along a predetermined path.

[0094] The irradiation head 1 is provided with a focus lens 10, a wedge prism 20, a protective glass 30, a rotating cylinder 40, a motor 50, a motor holder 60, a protection glass holder 70, a housing 80, and a duct 90, etc.

[0095] The focus lens 10 is an optical element in which a laser beam R transmitted from a laser oscillator 110 via a fiber to an irradiation head 1 enters after passing through a collimator lens (not shown).

[0096] The collimator lens is an optical element that parallelizes (collimates) a laser beam emitted from an end of a fiber into a substantially parallel beam.

[0097] The focus lens 10 is an optical element which converges (focuses) a laser beam R emitted from a collimator lens at a predetermined focal position.

[0098] As the focus lens 10, for example, a convex lens having positive power can be used.

[0099] Note that the beam spot BS, which is an irradiation point on the surface of the irradiation object O by the laser beam R, is arranged in a close state in the vicinity of the focal point or within the depth of focus (focusing state) or a state separated from the focus position (defocus state) .

[0100] The depth of focus means a range in an optical axis direction in which the beam diameter is less than or equal to a diameter of a predetermined allowable circle of confusion.

[0101] The wedge prism 20 is an optical element which deflects the laser beam R emitted from the focus lens 10 by a predetermined deflection angle θ (see FIG. 1) and makes the optical axis angles of the incident side and the exit side different.

[0102] The wedge prism 20 is formed in a plate shape in which the thickness thereof is continuously changed so that one of the thicknesses in the direction perpendicular to the optical axis direction of the incident side becomes larger than the thickness of the other.

[0103] The protective glass 30 is an optical element made of a flat glass or the like which is disposed close to the wedge prism 20 in the focus position side (the irradiation object O side and the beam spot BS side) along the optical axis direction.

[0104] The protective glass 30 is a protective member which prevents foreign matter, such as a peeled material scattered from the irradiation object O side, spatters, dust, or the like, from adhering to other optical elements such as the wedge prism 20.

[0105] The protective glass 30 is an optical element disposed closest to the focal point position along the optical axis direction of the optical system of the irradiation head 1, and is exposed to the object O side through the space S and the duct 90 which are explained later.

[0106] The focus lens 10, the wedge prism 20, and the protective glass 30 are formed by coating a surface of a member made of a transparent material such as an optical glass, for example, with a coating for preventing reflection and surface protection.

[0107] The rotary cylinder 40 is a cylindrical member that holds the focus lens 10 and the wedge prism 20 on the inner diameter side.

[0108] The rotary cylinder 40 is formed concentrically with an optical axis of the focus lens 10 and an optical axis of the laser beam R (an optical axis of the collimator lens) which is incident on the focus lens 10.

[0109] The rotary cylinder 40 is rotatably supported by a bearing (not shown), with respect to the housing 80, around a rotation center axis coinciding with an optical axis of the focus lens 10.

[0110] The rotary cylinder 40 is made of a metal such as an aluminum alloy or an engineering plastic.

[0111] The motor 50 is an electric actuator which rotationally drives the rotary cylinder 40 around a rotation center axis with respect to the housing 80. For example, the motor 50 is configured as an annular motor that is concentric with the rotary cylinder 40 and is provided on an outer diameter side of the rotary cylinder 40.

[0112] A stator (not shown) of the motor 50 is fixed to the housing 80 via a motor holder 60.

[0113] A rotor (not shown) of the motor 50 is fixed to the rotary cylinder 40.

[0114] The motor 50 is controlled by a motor drive unit 120 (see FIG. 2) so that the rotational speed of the rotary cylinder 40 substantially coincides with a desired target rotational speed.

[0115] To maintain a posture of an irradiation head 1 so that a rotation center axis of a rotary cylinder 40 is orthogonal to a surface near an irradiation part of an irradiation object O, and the motor 50 rotates a wedge prism 20 together with a rotary cylinder 40. Thus the beam spot BS is circularly scanned along the surface of the irradiation object O in an arc shape around the rotation center axis of the rotary cylinder 40.

[0116] When the irradiation head 1 is moved translationally along the surface of the irradiation object O in this state, the beam spot BS scans the surface of the object O while rotating in an arc shape.

[0117] Thus, when attention is paid to an arbitrary point on the irradiation object O, the laser beam R is incident in a pulse form only for a short time, and rapid heating and rapid cooling are sequentially performed in a short time.

[0118] At this time, a cleaning object (adhered matter) such as an old painting film, rust, a coating film etc. formed on the surface of the irradiation object O, or an adhered foreign substances, are crushed and scattered.

[0119] The motor holder 60 is a support member that holds the stator of the motor 50 in a predetermined position inside the housing 80.

[0120] The main body of the motor holder 60 is formed in a cylindrical shape and is fixed to the housing 80 in a state of being inserted into the inner diameter side of the housing 80.

[0121] An inner peripheral surface of the motor holder 60 is disposed facing an outer peripheral surface of the motor 50 and is fixed to a stator of the motor 50.

[0122] A purge gas channel 61 through which a purge gas PG flows is formed in a portion between an outer peripheral surface and an inner peripheral surface of the motor holder 60.

[0123] The purge gas PG is a gas that is ejected from the space S in contact with the irradiation object O side surface of the protective glass 30, which will be described later, in the inner cylinder 91 of the duct 90 when the irradiation head 1 is used (during irradiation). A surface portion of the protective glass 30 on the irradiation object O side is disposed so as to be exposed inside the space portion S.

[0124] The purge gas PG has a function of preventing dust, such as an old paint coating, rust, or a fragment of a film, which scatters from the irradiation object O side, or foreign matter, such as sputtering, from flying into the housing 80 and adhering to the protective glass 30.

[0125] The purge gas channel 61 is an opening formed through a portion of the motor holder 60 in an axial direction of the motor 50.

[0126] The purge gas PG discharged from the purge gas channel 61 is introduced into the inner diameter side of the inner cylinder 91 of the duct 90 via a channel provided in the housing 80.

[0127] The protective glass holder 70 is a member fixed to the inner diameter side of the housing 80 while holding the protective glass 30.

[0128] The protective glass holder 70 is formed in a disk shape, for example, in which a circular opening is formed in a central portion.

[0129] The laser beam R passes through an aperture from the wedge prism 20 side toward the irradiation object O side.

[0130] A recessed portion into which a protective glass 30 is fitted is formed on a surface portion of the protective glass holder 70 on the irradiation object O side.

[0131] The protective glass 30 is held inside the housing 80 in a state in which it is fitted into this recess.

[0132] The protective glass 30 is detachably attached to the protective glass holder 70 so as to be replaceable when contamination or burnout occurs.

[0133] A surface portion of the protective glass holder 70 on the side opposite to the irradiation object O side is opposed to an end surface of the motor holder 60 on the irradiation object O side with a space.

[0134] This space constitutes a part of a flow path (a part of the fluid supply unit) which introduces the purge gas PG introduced from the purge gas flow path 61 of the motor holder 60 into the space S on the irradiation object O side of the protective glass 30.

[0135] The housing 80 is a cylindrical member constituting a casing of the main body of the irradiation head 1.

[0136] In the inside of the housing 80, the focus lens 10, the wedge prism 20, the protective glass 30, the rotary cylinder 40, the motor 50, the motor holder 60, the protection glass holder 70, etc. which were mentioned above are stored. Also, the end on the irradiation head 1 side of the fiber and the collimate lens, which is not illustrated, are stored.

[0137] The duct 90 is a double cylindrical member which is provided so as to protrude from an end portion of the housing 80 on the irradiation object O side.

[0138] The duct 90 includes an inner cylinder 91, an outer cylinder 92, a dust collector connecting cylinder 93 etc.

[0139] The motor holder 60, the protective glass holder 70, and the housing 80 described above are made of a metal such as an aluminum alloy or an engineering plastic etc.

[0140] The inner cylinder 91 is formed in a cylindrical shape.

[0141] The laser beam R passes through the inner diameter side of the inner cylinder 91 and is emitted to the irradiation object O side.

[0142] At an end of the inner cylinder 91 on the side of the housing 80, a small diameter portion 91a is formed in a stepped shape with respect to the other portion.

[0143] A purge gas PG is introduced from the inside of the housing 80 into the space S inside the small diameter portion 91a.

[0144] At an end portion of the inner cylinder 91 on the irradiation object O side, there is formed a tapered portion 91b which is tapered so as to have a smaller diameter of the irradiation object O side.

[0145] The tapered portion 91b has a function of reducing the flow the purge gas PG and increasing the flow speed while allowing the passage of the laser beam R.

[0146] The outer cylinder 92 is a cylindrical member arranged concentrically with the inner cylinder 91 and is provided on an outer diameter side of the inner cylinder 91.

[0147] Between the inner peripheral surface of the outer cylinder 92 and the outer peripheral surface of the outer cylinder 91, a continuous gap is formed over the entire circumference.

[0148] At an end of the outer cylinder 92 on the side of the housing 80, a small diameter portion 92a formed in a stepped shape with respect to the other portion is formed.

[0149] The small diameter portion 92a is fixed in a state of being fitted in an end portion of the housing 80 on the side of the irradiation object O.

[0150] An edge of an end 92b of the outer cylinder 92 on the irradiation object O side is formed to be inclined with respect to a rotation center axis of rotation of the rotary cylinder 40, so that an upper side becomes a housing 80 side relative to the lower side, at the time of normal use of irradiation with the rotation center axis of the rotary cylinder 40 being horizontal.

[0151] The dust collector connecting tube 93 is a cylindrical tube body which protrudes from the outer cylinder 92 toward the outer diameter side and is connected in a state of communicating with the inner diameter side of the outer cylinder 92.

[0152] The dust collector connecting tube 93 is provided below the outer cylinder 92 during the aforementioned normal use.

[0153] The dust collector connecting tube 93 is disposed to be inclined with respect to the outer cylinder 92 so as to depart (separate) from the outer cylinder 92 as approaching to the housing 80 side from the irradiation object O side.

[0154] One end of the dust collector connecting tube 93 is connected to the outer cylinder 92 in the vicinity of an end of the outer cylinder 92 on the irradiation object O side so as to communicate with the inside of the outer cylinder 92.

[0155] The end of another side of the dust collector connection tube 93 is connected to the dust collector 140 (refer to FIG. 2), and vacuum suction is carried out so that an inside may serve as negative pressure.

[0156] In the 1st embodiment, while emitting the laser beam R, by rotating the rotating cylinder 40 and the wedge prism 20, the beam spot BS rotates on an arc of a predetermined radius along the surface of the irradiation object O.

[0157] In this state, by moving the irradiation head 1 parallel along the surface of the irradiation object O, it is possible to perform a cleaning process in which the beam spot BS scans the surface of the irradiation object O.

[0158] Further, in the 1st embodiment, an inert gas such as nitrogen gas, which also functions as a shield gas, can be used as the purge gas PG.

[0159] In this inert gas, a region including the beam spot BS and its turning radius (within the scanning pattern) is made into an atmosphere filled with nitrogen, and is blocked from oxygen.

[0160] FIG. 2 is a block diagram schematically showing a system configuration of the laser irradiation apparatus according to the 1st embodiment.

[0161] The laser irradiation device includes a laser oscillator 110, a motor driving device 120, a purge gas supplying device 130, a dust collecting device 140, an irradiation condition diagnosing part 200, and etc.

[0162] The laser oscillator 110 generates a laser beam which is irradiated as a laser beam R onto an irradiation object, and supplies the laser beam to an irradiation head 1 via a fiber.

[0163] As the laser oscillator 110, for example, a CW laser having an average power of about 1 kW can be used, but the present invention is not limited thereto as will be described later.

[0164] The motor driving device 120 is a power supply device that supplies driving electric power to the motor 50.

[0165] The motor driving device 120 has a function of adjusting a rotational speed of the motor 50.

[0166] A motor driving device 120 performs feedback control so that an actual rotation speed of a motor 50 detected by an irradiation condition diagnosing part 200 coincides with a predetermined target rotation speed.

[0167] In the 1st embodiment, a function of detecting the rotational speed of the motor 50 based on the acoustic information is provided. This will be described in detail later.

[0168] The purge gas supply unit 130 supplies a purge gas PG such as nitrogen gas to the purge gas flow path 61.

[0169] As the purge gas supply device 130, for example, a container in which a purge gas is stored in a compressed state or a nitrogen gas generator can be used.

[0170] The dust collecting device 140 collects a peeled substances or the like scattered from an irradiation object when the laser beam R is irradiated.

[0171] The dust collector 140 is connected to the dust collector connecting tube 93, and has a negative pressure generating source for sucking negative pressure, and a dust collecting means such as a cyclone for collecting the scattered matter.

[0172] The irradiation state diagnosis unit 200 acquires the acoustic information generated by the beam spot BS or the irradiation head 1 itself, and diagnoses the irradiation state of the beam spot BS and the state of the irradiation head 1 based on the acoustic information.

[0173] The irradiation state diagnosis unit 200 is configured as a computer including an information processing unit such as a CPU, a storage unit such as a RAM and a ROM, an input/output interface, and a bus connecting these components etc.

[0174] The irradiation state diagnosis unit 200 executes a laser irradiation state diagnosis program for performing the laser irradiation state diagnosis method of the 1st embodiment.

[0175] A 1st microphone 201, a 2nd microphone 202, a process end indicator 203, a defocus indicator 204, an inclination indicator 205, an emergency stop indicator 206 etc. are connected to the irradiation state diagnosis unit 200.

[0176] The 1st microphone 201 and the 2nd microphone 202 are sound collecting devices for acquiring acoustic information in the vicinity of the beam spot BS.

[0177] For example, a unidirectional microphone may be used as the 1st microphone 201 and the 2nd microphone 202.

[0178] As shown in FIG. 1, for example, the 1st microphone 201 and the 2nd microphone 202 are arranged in the vicinity of an end portion on the irradiation object side of the irradiation head 1 so as to be directed to the vicinity of the beam spot BS in a state of being separated toward a radial direction of the duct 90.

[0179] Thus, the acoustic information around the beam spot BS can be acquired with high sensitivity, and the sound generated by the irradiation head 1 can be acquired to a certain extent.

[0180] The process end indicator 203 is an informing means for indicating to the user that the peeling process has finished, when the irradiation condition diagnosing unit 200 determines that the peeling of the deposit does not occur substantially from the surface of the irradiation object.

[0181] The defocus indicator 204 is an informing means which indicates to the user that a defocus state is arising and indicates a method of moving the irradiation head 1 (i.e., a direction of moving away from the irradiation object or approaching thereto) for changing into a focus state, when the irradiation state diagnostic section 200 determines that the beam spot BS is in the defocus state in which the beam spot BS deviates from the depth of focus of the laser beam R.

[0182] The inclination indicator 205 is an informing means which indicates to the user that an inclined state has occurred and indicates an operation direction of an irradiation head 1 for eliminating an inclined state, when the irradiation condition diagnostic part 200 determines that the axial direction of the irradiation head 1 (the rotation center axis direction of the rotary cylinder 40) is inclined by a predetermined value or more relative to the normal-line direction of the surface of the irradiation object.

[0183] An emergency stop indicator 206 is an informing means for indicating to the user that the emergency stop is performed, when the irradiation condition diagnosis unit 200 detects that the laser beam R is irradiated in a state of being deviated from the irradiation object and the irradiation is urgently stopped.

[0184] Each of these indicators includes, for example, a warning lamp, an image display device, a sound output device, and the like.

[0185] The irradiation state diagnosis unit 200 includes an average calculation unit 210, a fast Fourier transform unit 220, an acoustic feature extraction unit 230, and a sound recognition unit 240.

[0186] The irradiation state diagnosis unit 200 has a function of an acoustic information acquisition unit, a peeling state determination unit, a focus state determination unit, an inclination state determination unit, an abnormality determination unit, a speed detection unit, and a sound recognition unit.

[0187] These functions will be described in detail later.

[0188] The average value calculation unit 210 calculates an average value of sound data collected by the 1st microphone 201 and the 2nd microphone 202, and transmits the average value to the fast Fourier transform unit 220. In the fast Fourier transform unit 220, to the acoustic information transmitted from the average value calculation unit 210, a known fast Fourier transform (FFT) process is performed and data is converted from the time domain into the frequency domain.

[0189] The acoustic feature extraction unit 230 extracts a component of a predetermined frequency band from the acoustic information of the frequency domain generated by the fast Fourier transform unit 220, and determines the irradiation state of the laser beam R at the beam spot BS based on intensity (amplitude) thereof and the like.

[0190] The sound recognition unit 240 recognizes a component having a predetermined characteristic (such as a specific sound described later) from the acoustic information.

[0191] Hereinafter, the function of the irradiation state diagnosis unit 200 will be described in detail.

<Peeling State Determining Function>

[0192] The irradiation state diagnosis unit 200 has a function of determining whether or not adhered substances which are the object to be processed such as rust or an old paint coating, are crushed and peeled from on the surface of the irradiation object O, which is scanned by the beam spot BS of the laser beam R.

[0193] Conventionally, confirmation of the degree of rust removal in a rust-removing work using a laser has been performed principally by visual inspection.

[0194] However, visual confirmation depends on subjective judgment of an operator, and it is difficult to eliminate individual differences between operators.

[0195] Thus, for example, in JIS Z 2358, it is defined that the degree of rust removal is evaluated by a color sample or a color meter. However, this method is suitable for final evaluation after execution, but requires time for evaluation, so that it is difficult to immediately feed-back the measurement result to the execution condition.

[0196] In addition, during actual execution, it is difficult to determine in real time whether or not an appropriate execution state (such as whether or not an irradiation head is held at an appropriate distance and an angle to an irradiation object) is performed.

[0197] On the other hand, in the 1st embodiment, by discriminating the peeling state using the acoustic information, it is possible to diagnose the peeling state independent of the subjectivity of the operators . In addition, such a diagnosis can be made in real time and can be immediately fed back to the execution conditions.

[0198] FIG. 3 is a diagram showing an example of a frequency spectrum of acoustic information at the time of laser irradiation in the laser irradiation apparatus according to the 1st embodiment.

[0199] In FIG. 3, a horizontal axis represents frequency, and a vertical axis represents amplitude (intensity and sound pressure).

[0200] The inventors of the present invention have found that in a cleaning process in which rust, which is an adhered substance on the surface of an irradiation object, is peeled off by irradiation with a laser beam R, the frequency distribution characteristic of acoustic information changes with the progress of the peeling process.

[0201] FIG. 4 is a diagram showing an example of the intensity transition of acoustic information for each frequency band when removing (cleaning) the rust in the laser irradiation apparatus of the 1st embodiment.

[0202] In FIG. 4, a horizontal axis represents time, and a vertical axis represents an average value of an acoustic signal intensity in a predetermined frequency band.

[0203] Data from 900 Hz to 1100 Hz is shown in a solid line.

[0204] Data from 3 kHz to 6 kHz are indicated by a dashed line (dotted line).

[0205] Data from 9.9 kHz to 10.1 kHz are shown by a 1 dot chain line.

[0206] Data from 14 kHz to 16 kHz is shown by a 2 dot chain line.

[0207] As shown in FIG. 4, in the band of 900 Hz to 1100 Hz indicated by a solid line, it can be seen that, when the irradiation processing is repeated, the intensity decreases sequentially.

[0208] It is considered that this frequency band includes sound generated when the rust adhering to the surface of an irradiation object is crushed by the rapid heat input and subsequent cooling when the beam spot BS passes during the scanning.

[0209] Therefore, based on the absolute value of the sound signal intensity of the specific frequency band or the decrease of the relative value relative to the other frequency band, it is determined whether or not the peeling state has been settled (peeled substances has reduced).

[0210] For example, when such an intensity becomes equal to or lower than a predetermined threshold value, the end of the peeling process is determined, the emission of the laser beam R is stopped, or the intensity is reduced, and the end of the peeling process is notified to the user by the process end indicator 203.

<A Focus Judgment>

[0211] The irradiation state determination unit 200 has a function of determining whether the focus position of the laser beam R is in a focus state in which the focus position of the laser beam R substantially coincides with the surface of the irradiation object O or in a defocus state in which the focus position is apart from the surface of the irradiation object O based on the acoustic information.

[0212] FIG. 5 is a diagram showing an example of a spectrogram according to the focus and defocus of acoustic information at the time of laser irradiation in the laser irradiation apparatus of the 1st embodiment.

[0213] In FIG. 5, a horizontal axis represents time, and a vertical axis represents frequency. Further, it is shown that the intensity of the acoustic signal is higher as the dark color becomes darker.

[0214] In FIG. 5, the upper portion shows data in a focus state, and the lower portion shows data in a defocus state.

[0215] FIG. 5 shows data when 3 irradiations are intermittently performed.

[0216] At this time, at the time of focusing shown in the upper stage, it is found that the signal intensity in the predetermined frequency band A is significantly larger at the irradiation time than at the non-irradiation time, but this phenomenon is not observed at the time of defocus.

[0217] Therefore, by comparing the intensity of such frequency band A with a preset threshold value, it is possible to determine the focus state.

[0218] Alternatively, a configuration may be adopted in which reference data (reference sound data) for the intensity of each of the audio signals at the time of focus is held in advance, and the defocus state is determined based on the deviation of the intensity distribution of the actually acquired sound data from the reference data.

<Inclination Judging>

[0219] The irradiation state diagnosis unit 200 has a function of determining whether the rotation center axis of the wedge prism 20 in the irradiation head 1 is in a rightly facing state in which the rotation center axis coincides with a normal-line direction of the surface of the irradiation object, or in an inclined state in which the irradiation head 1 is inclined with respect thereto.

[0220] FIG. 6 is a diagram showing an example of acoustic information expressed in a frequency domain at the time of tilting and non-tilting of an irradiation head in the laser irradiation apparatus of the 1st embodiment.

[0221] In FIG. 6, a horizontal axis represents a frequency, and a vertical axis represents an intensity of acoustic information.

[0222] When the irradiation head 1 is in the rightly facing positive facing state (non-inclined state), the state of focus at the beam spot BS becomes constant regardless of the position at which the beam spot BS is rotated.

[0223] On the other hand, in the inclined state, the distance from the focus lens 10 varies depending on the position of the beam spot BS, so that the focus state and the defocus state change periodically. This variation period coincides with the rotation period of the wedge prism 20.

[0224] Therefore, in the inclined state, the intensity of the regular peak train, which appears in correlation with the rotation period of the wedge prism 20, increases with respect to the rightly facing state, as indicated by an ellipse indicated by a broken line in the drawing.

[0225] Based on an increase in intensity of such a peak, it is possible to determine an inclination state, and it is also possible to estimate a degree of inclination based on the intensity.

[0226] If the state of inclination is determined, the irradiation state diagnosis unit 200 activates the inclination indicator 205 and urges the operator to correct the posture of the irradiation head 1.

<Motor Rotation Speed Judging>

[0227] The irradiation state diagnosis unit 200 has a function for detecting a rotation speed of the motor 50 (equal to the rotation speed of the wedge prism 20 and the rotation cylinder 40) based on a specific frequency component included in the sound information.

[0228] The acoustic information includes a component of a specific frequency band proportional to the rotational speed of the motor 50.

[0229] The irradiation state diagnosis unit 200 can detect the rotation speed of the motor 50 based on the transition of the frequency band caused by the motor 50.

[0230] The detected rotational speed can be used, for example, for controlling the rotational speed of the motor 50 by the motor drive device 120.

<Motor, Bearing Abnormality Determination>

[0231] The irradiation state diagnosis unit 200 has a function of detecting an abnormality of the motor 50 and a bearing supporting the rotation cylinder 40 based on the acoustic information.

[0232] The irradiation state diagnosis unit 200 holds the sound information acquired when the motor 50 and the rotation cylinder 40 are normal as reference data. When there is a specific frequency band not included in the reference data and a component having an intensity equal to or higher than a predetermined value, it is determined that an acoustic signal related to this component is an abnormal sound due to the failure of the motor 50 and the bearing.

[0233] When an abnormal sound is detected, an irradiation state diagnosing unit 200 determines that some trouble has occurred in an irradiation head 1, and stops the emission of a laser beam R and the driving of a motor 50, and actuates an emergency stop indicator 206.

<The Emergency Stop by Specific Sound>

[0234] When the irradiation condition diagnosing unit 200 recognizes a specific sound having characteristics set in advance in the sound information, it has a function of stopping the emission of the laser beam R or changing the irradiation condition such as lowering the intensity.

[0235] As a specific sound, for example, a sound generator such as a speaker, a buzzer, or the like that outputs a specific sound having a specific frequency, a sound generation pattern (e.g., an intermittent sound, a frequency change, or the like) is arranged around an operator (including an operator carrying the sound generator), thereby preventing the irradiation head 1 from being erroneously irradiated to an operator or the like. Here, the worker is not limited to a operator who operates the irradiation head 1, and includes all persons existing in the work area.

[0236] Further, by arranging such a sound generating body around the irradiation object O, it is possible to recognize that the light emitting body is close to the sound generating body or that the irradiation head 1 is directed, and thus it is possible to prevent an object other than the irradiation object O from being erroneously irradiated.

[0237] Further, by generating a specific sound by an active behavior such as blowing a whistle by an operator, an emergency stop can be performed without operating the direct irradiation device.

[0238] Further, the specific sound may be a voice of an operator.

[0239] For example, a configuration may be adopted in which the irradiation apparatus is urgently stopped when the user has recognized a word (e.g., “dangerous”) indicating a shout or a risk.

[0240] According to the 1st embodiment described above, the following effects can be obtained. [0241] (1) Based on the characteristics of the sound generated when the adhered substances such as rust is peeled off from the surface of the irradiation object O, the peeling state such as the peeling amount of the adhered substances by the irradiation of the laser beam R is discriminated, and when the peeling process is finished, it is possible to accurately determine this state in real time. [0242] (2) In a focus state in which the focal position of the laser beam R is close to the surface of the irradiation object O, and, in a defocus state in which the focus position is relatively spaced from the surface of the irradiation object O compared to the focus state, the peeling state such as rust on the surface of the irradiation object changes, and thus, the characteristics such as the sound pressure and the frequency of the sound generated by the peeling of the rust or the like change.

[0243] Using this characteristics, it is possible to determine the focus state and the defocus state based on the intensity of the specific frequency band A.

[0244] (3) If the irradiation head 1 inclines to the irradiation object O when beam-spot BS rotates in a circle and scans the surface of the irradiation object O, responding to the position of beam-spot BS on a circle, a change in the focus state results in a periodic sound change having the same period as the rotation period.

[0245] According to the 1st embodiment, by determining the inclination state of the irradiation head 1 based on the periodic change of the acoustic information (the peak of a specific frequency), it is possible to appropriately detect the inclination of the irradiation head 1 with a simple configuration without providing a position sensor, an acceleration sensor, or the like for detecting, for example, the position and the posture of the irradiation head 1.

[0246] (4) By providing the 1st and 2nd microphones 201,202 on the irradiation head 1, it is unnecessary to install and remove the sound collecting device provided separately from the irradiation head 1, and the process can be simplified.

[0247] Further, each microphone 201,202 can be held in a state of being directed to the vicinity of the beam spot BS reliably.

[0248] (5) By processing the output of the plurality of microphones 201,202 to generate acoustic information, it is possible to improve the quality of the signal and to improve the diagnostic accuracy of the irradiation state. Specifically, by using an average of outputs of the microphones 201,202, directivity toward the vicinity of the beam spot BS can be enhanced.

[0249] (6) By using the acoustic information acquired by each microphone 201,202, it is possible to discriminate the rotational speed and abnormality of the drive unit such as the motor 50 etc., together with the laser irradiation state, without using any other dedicated sensor or the like.

[0250] (7) It is possible to improve the safety and convenience by stopping the emission of the laser beam in response to the detection of the specific sound indicating that the emission of the laser beam should not be continued, in such as a dangerous state.

The 2nd Embodiment

[0251] Next, a laser irradiation state diagnosis method, a laser irradiation state diagnosis program, a laser irradiation state diagnosis apparatus, and a laser irradiation apparatus according to the 2nd embodiment of the present invention will be described.

[0252] In each of the embodiments described below, portions substantially common to the previous embodiments will be denoted by the same reference numerals, and description thereof will be omitted, and mainly differences will be described.

[0253] In the 2nd embodiment, instead of the 1st microphone 201 and the 2nd microphone 202 provided in the irradiation head 1 in the 1st embodiment, a sound collecting device (a microphone) is provided independently from the irradiation head 1 is provided in proximity to the irradiation object to obtain acoustic information.

[0254] According to the 2nd embodiment described above, in addition to the effects similar to those of the 1st embodiment described above (except for those described in the paragraph (4)), noise generated in the acoustic information in the motor and the like is hardly included in the acoustic information, and diagnosis of the irradiation state can be performed more accurately.

The 3rd Embodiment

[0255] Next, a laser irradiation state diagnosis method, a laser irradiation state diagnosis program, a laser irradiation state diagnosis apparatus, and a laser irradiation apparatus according to the 3rd embodiment of the present invention will be described.

[0256] In the 3rd embodiment, instead of the 1st microphone 201 and the 2nd microphone 202 provided in the irradiation head 1 in the 1st embodiment, a sound collection device (an acoustic pickup) provided independently from the irradiation head 1 is attached to an irradiation object to obtain acoustic information.

[0257] In the 3rd embodiment described above, by obtaining the acoustic information by the solid propagation from the irradiation object, in addition to the effects similar to those of the 1st embodiment described above (except for those described in the paragraph (4)), the noise and the like of the surrounding environment are not easily picked up by the sound collecting device, accordingly it is possible to further improve the accuracy of the diagnosis of the irradiation state.

The 4th Embodiment

[0258] Next, a laser irradiation state diagnosis method, a laser irradiation state diagnosis program, a laser irradiation state diagnosis apparatus, and a laser irradiation apparatus according to the 4th embodiment of the present invention will be described.

[0259] In the 4th embodiment, irradiation conditions of the irradiation head 1, by modulating at least one of the intensity of laser light (oscillator output), the rotation speed of the wedge prism and the focus position for example, in a period T, and by performing a noise elimination process called a lock-in amplifier, quality of sound (S/N) is improved.

[0260] The lock-in amplifier is a technique suitable for extracting a small repetitive signal from a signal including noise.

[0261] When the irradiation condition is modulated at a period T, if the acoustic signal or a function S (t) of a time t of a frequency spectrum is changed in a period T,

S(t)×sin (2πt/T), and, S(t)×cos (2πt/T).

is integrated in time, noise is canceled and only a signal synchronized with a period T is left, so that only signals resulting from irradiation of the laser beam R can be detected with high accuracy.

[0262] According to the 4th embodiment described above, it is possible to extract only the signal synchronized with a predetermined period, to improve the S/N ratio, and to diagnose the laser irradiation state with higher accuracy.

The 5th Embodiment

[0263] Next, a laser irradiation state diagnosis method, a laser irradiation state diagnosis program, a laser irradiation state diagnosis apparatus, and a laser irradiation apparatus according to the 5th embodiment of the present invention will be described.

[0264] In the 5th embodiment, the irradiation head 1 has an autofocus mechanism for changing the position of the focus with respect to the irradiation head 1 by, for example, driving the focus lens 10 in the optical axis direction.

[0265] In the 5th embodiment, while the focus position relative to the irradiation object O in the optical axis direction of the focus lens 10 is continuously or intermittently changed by an autofocus mechanism, the aforementioned focus state is determined. Thus, an autofocus control is performed and the position of the focus lens 10 is automatically set so as to obtain a focus state.

[0266] According to the 5th embodiment described above, in addition to the effects similar to those of the 1st embodiment described above, it is possible to reliably detect the position of the irradiation head which can obtain the focus state and to ensure the processing quality.

(Modification)

[0267] The present invention is not limited to the above described embodiments, and various modifications and changes can be made without departing from the scope of the present invention.

[0268] (1) The configuration of the laser irradiation state diagnosis method, the laser irradiation state diagnosis program, the laser irradiation state diagnosis apparatus, and the laser irradiation apparatus is not limited to the above-described embodiments. It can be modified as appropriate.

[0269] For example, the shapes, the structures, the materials, the manufacturing method, the arrangement, quantity and the like of the respective members constituting the laser irradiation state diagnosis apparatus, the laser irradiation apparatus, and the like can be appropriately changed.

[0270] In addition, even in the type of laser, such as a fiber laser, a YAG laser, and a CO.sub.2 laser, and in an oscillation method such as the pulse laser and the QCW laser etc. can be appropriately selected.

[0271] (2) In the laser irradiation apparatus of each of the embodiments, the laser beam R is rotated by rotating the wedge prism, but the present invention is not limited thereto, and the irradiation position may be scanned along a predetermined pattern by another method.

[0272] For example, a galvanometer scanner may be used to scan an irradiation object. Also, the scanning pattern is not limited to circular rotation, and may be, for example, a turn along a polygonal trajectory or another pattern.

[0273] (3) The arrangement of the sound collecting device in the sound information acquiring unit shown in each embodiment is an example, and can be changed as appropriate.

[0274] For example, in the 1st embodiment, for example, a pair of microphones is used as a sound collecting device, however, the number of sound collecting devices used is not particularly limited and may be changed as appropriate.

[0275] (4) A method of calculating and determining an acoustic signal in each embodiment is an example, and can be changed as appropriate.

[0276] (5) Although each of the embodiments has been described as an example of removing rust (laser cleaning), the present invention can be applied to, for example, peeling of an old painting film and cleaning of foreign matters. Further, the determination of the focus state and the tilt state is applicable not only to laser cleaning but also to other applications such as substrate adjustment.

TABLE-US-00001 [Explanation of letters or numerals]  1 irradiation head  10 focus lens  20 wedge prism  30 protective glass  40 rotary cylinder  50 motor  60 motor holder  61 purge gas passage  70 protection glass holder  80 housing  90 duct  91 inner cylinder  91a small diameter portion  91b tapered portion  92 outer cylinder  92a small diameter portion  92b end  93 dust collector connecting tube 110 laser oscillator 120 motor driving device 130 purge gas supplying device 140 dust collector 200 irradiation state diagnostic unit 201 1st microphone 202 2nd microphone 203 process end indicator 204 defocus indicator 205 inclination indicator 206 emergency stop indicator 210 average value 220 fast Fourier calculation unit transform unit 230 acoustic feature 240 sound recognition unit extraction unit