JP2014079664A - Coating film removal method and laser beam application device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating film removal method for efficiently removing a coating film on a surface of a structure, and a laser beam application device.SOLUTION: This invention provides a coating film removal method for removing a coating film on a surface 20 of a structure, the method including preliminary treatment to form slits 23 on the coating film, and peeling treatment to apply a laser beam 30 to the coating film in an area including the slits and peel at least part of the coating film.

Description

  The present invention relates to a technique for removing a coating film on the surface of a structure by laser irradiation. In particular, the structure is portable for fixed or large structures such as bridges, buildings, and ships. The present invention relates to a coating film removing method and apparatus for removing a relatively thick coating film by irradiating a laser with a laser head.

  The surface of the base material (steel) is used to prevent corrosion in order to safely use structures that are difficult to move, such as bridges, highways, railway elevated tracks, buildings, tanks, and machinery, for a long period of time. It is necessary to periodically remove, remove, and repaint the paint film applied to. Conventionally, as a method for removing a coating film, there have been a method by blasting such as sand blasting for removing the coating film by spraying sand, a method using a coating film removing agent, and a method using a mechanical tool.

  In the blasting method, a large amount of secondary waste is generated. This secondary waste is a mixture of dust from coatings containing harmful substances such as lead, hexavalent chromium, and PCB, and abrasives such as silica sand and garnet. Is also big. Moreover, since the abrasive is blown with compressed air, there is a risk that even the base material under the coating layer may be damaged. In addition, there is a problem that a large noise is generated when the abrasive material collides. Each of the methods using the coating film remover and the machine tool has a problem that the processing area per hour is low and is not efficient, and each has a problem that a waste of chemicals is generated and noise is high. is there.

  And, when removing the coating on the outer panel of an aircraft or the like, conventionally, a highly toxic chemical was sprayed on the painted surface and the coating film was scraped off manually. In order to avoid the danger, a method for removing a coating film by a laser processing apparatus is disclosed. The laser processing apparatus described in Patent Document 1 includes a lens that irradiates a surface of a processing target with a laser, a lens support mechanism that supports the lens and can adjust the height from the processing target surface to the lens, and a laser irradiation portion. Gas ejection means for blowing gas is provided. Further, it is described that the gas suction port arranged in the box-shaped container exhausts the gas in the box-shaped container and discharges the removed matter scattered from the laser irradiation portion.

  A first deflector that is disposed in the optical path of the laser incident on the lens and moves the laser irradiation position in a first direction within the surface of the object to be processed by changing a traveling direction of the laser; A second laser beam is disposed in the optical path of the laser incident on the lens and moves the laser irradiation position in a second direction intersecting the first direction in the surface of the object to be processed by changing the laser traveling direction. It is described that a sweeping process of sweeping the laser irradiation position in a first direction using a deflector is performed a plurality of times while shifting in a second direction intersecting with the first direction.

  In such a laser processing apparatus, the laser irradiation head is attached to the tip of a manipulator arm, and the manipulator arm is controlled by the manipulator body to move and support the laser irradiation head to a desired position on the surface of the processing object. Has been.

Japanese Patent Laid-Open No. 10-309899

  According to the technique described in Patent Document 1, the coating film on the surface of the processing object can be removed by laser ablation without using chemicals. However, in Patent Document 1, a first deflector such as a galvanometer mirror or a polygon mirror is used for the scanning optical system, and the laser irradiation position is scanned linearly (hereinafter referred to as “linear scanning”). In such a method of repeating linear scanning, it is difficult to efficiently process a wide range in a short time, and it is not possible to process a wide range surface of a structure such as a bridge at a low cost.

  In particular, in the case of a thick coating film, the layer of the coating film has to be scraped from the surface little by little.

  Further, since the laser irradiation head described in Patent Document 1 is supported by a manipulator arm and moved to a desired position, it can be used for an environment where a sufficient work space cannot be secured or a complex-shaped structure. Difficult to use. It is also difficult for the operator to carry around while carrying it. In the first place, the laser processing apparatus described in Patent Document 1 is a laser processing apparatus for applying to removal of a coating film of an aircraft or the like stored in a factory, and consideration is given to moving the laser processing apparatus itself. Absent. That is, the method for removing a coating film described in Patent Document 1 cannot be applied to the removal of a coating film on a structure that is difficult to move (for example, a bridge, a highway, an elevated railway line, a building, or the like).

  An object of this invention is to provide the coating-film removal method which can solve at least one part of the problem mentioned above, and the laser irradiation apparatus used for it.

In order to solve the above-described problems, the present invention provides a coating film removing method for removing a coating film on the surface of a structure, which includes a pretreatment for forming a cut in the coating film, and a coating film in a region including the cut. And a peeling treatment for peeling at least a part of the coating film. Moreover, it is preferable to form a segment by the notch containing at least one of a straight line and a curve in the pretreatment. The area of the segment is preferably in the range of 9 to 2500 mm ² .

  In the coating film removing method, at least a part of the layer of the coating film may be left. Moreover, it is preferable that the film thickness of a coating film is 0.3 mm or more. Moreover, it is preferable to have the acceleration | stimulation process for accelerating | stimulating peeling of the coating film of the area | region containing a notch simultaneously or after a peeling process.

  In the coating film removing method, the acceleration treatment may spray a fluid on the coating film. The acceleration treatment may give a physical force to the coating film.

  In the coating film removing method, the laser irradiation apparatus includes a laser oscillator, a fiber that transmits a laser output from the laser oscillator, and a laser head that irradiates a laser transmitted through the fiber. The head may perform at least one of the pretreatment and the peeling treatment by using a laser irradiation apparatus including a wedge prism that deflects the laser with respect to the optical axis and a driving unit that rotates the wedge prism.

  Further, in the coating film removing method, a laser irradiation apparatus comprising: a laser oscillator; a fiber that transmits a laser output from the laser oscillator; and a laser head that irradiates a laser transmitted through the fiber, A first wedge prism for deflecting the laser with respect to the optical axis; a second wedge prism for further deflecting the laser deflected by the first wedge prism with respect to the optical path; a first wedge prism and a second wedge; You may perform at least one of a pre-process and a peeling process using the laser irradiation apparatus provided with the drive means to rotate a prism.

  In addition, in the coating film removal method described above, by controlling the rotation direction and rotation speed of each wedge prism, and the distance between each wedge prism and the phase difference in the rotation direction, the laser irradiation point is linear and curved. Alternatively, the preprocessing may be performed by scanning.

  Alternatively, in the coating film removing method, the first and second wedge prisms are rotated in substantially the same rotational speed in the same direction, while changing the distance between the wedge prisms or the phase difference in the rotational direction, In the pretreatment, circular or annular cuts having different sizes may be formed. Alternatively, the first and second wedge prisms may be rotated in opposite directions at substantially the same rotational speed to form a substantially straight cut in the pretreatment. A blade may be used in the pretreatment.

  The present invention relates to a laser oscillator, a fiber for transmitting a laser output from the laser oscillator, and a portable laser for focusing the laser transmitted through the fiber and irradiating the coating film on the surface of the structure. A laser irradiation apparatus including a head, wherein the scanning optical system rotates a wedge prism that deflects the laser with respect to the optical axis, and the wedge prism about the optical axis at a predetermined rotational speed and rotational direction. And driving means for causing the laser to scan, forming a cut in the coating film, and then irradiating the coating film in a region including the cut in a circle to peel at least a part of the coating film. It is characterized by.

  In the laser irradiation apparatus, it is preferable to have fluid spraying means for spraying fluid onto the coating film in the region including the cut. Moreover, it is preferable that an attachment or a hood is provided at the tip of the laser head, and the attachment or the hood has an accelerating means for accelerating the peeling of the coating film.

  According to the present invention, a relatively thick coating film (0.3 mm or more, particularly 1.0 mm or more) can be efficiently peeled off, and the surface of a wide range of structures can be processed at low cost. In addition, according to the method for removing a coating film of the present invention, the laser marks on the base material after removing the coating film can be made inconspicuous compared with the case where the pretreatment is not performed. Furthermore, using a transportable and movable laser irradiation device including a small and light laser head, the coating film on the surface can be efficiently peeled off at the site of a structure that is difficult to move. Other effects will be described in the mode for carrying out the invention.

Explanatory drawing which shows the outline of the coating-film removal method of this invention (A) (B) (C) (D) is explanatory drawing which shows the example of the shape of a notch. (A) (B) is explanatory drawing which shows the example of the shape of the cross section of a notch Example of first scanning optical system of laser irradiation apparatus of the present invention Explanatory drawing which shows the locus | trajectory of the laser irradiation point by the example of a 1st scanning optical system Example of configuration of second scanning optical system (A) (B) is explanatory drawing which shows the locus | trajectory of the laser irradiation point by the example of a 2nd scanning optical system. (A) (B) is explanatory drawing which shows the example of a 3rd scanning optical system, and the example of the locus | trajectory of a laser irradiation point by it. (A) (B) is explanatory drawing which shows the example of a 4th scanning optical system, and the example of the locus | trajectory of a laser irradiation point by it. (A) (B) is explanatory drawing which shows the example of a 5th scanning optical system, and the example of the locus | trajectory of a laser irradiation point by it.

  Conventionally, when a coating film on the surface of a structure is repainted, much labor, cost, and time are required to remove the thick coating film. As a result of earnest research, the applicant of the present application, after forming a cut in the coating film on the surface of the structure, irradiating the cut coating film with a laser efficiently and in a short time. It was found that it can be peeled off. In particular, in the case of a thick coating film (for example, 0.3 mm or more, particularly 1.0 mm or more), it was possible to peel a coating film in a certain region at a time along the cut depending on the place.

  As shown in FIG. 1, in the coating film removing method of the present invention, first, an appropriate cut 23 is formed in the coating film on the surface 20 to be processed of the structure (hereinafter referred to as “pretreatment”). The segment 28 may be formed by this cut. Here, the “segment” is an area defined by cutting. The segment is preferably formed by a region (for example, a rectangle, a sector, a circle, or the like) closed by a cut (reference numeral 28 in FIGS. 2A and 2B), but a partially open region (open region). , The segment may be partitioned by virtual notches due to the periodicity of the notches). In other words, the cuts do not have to be continuous, for example, straight cuts may be arranged in parallel at equal intervals, or a shape in which a plurality of crosses are arranged (FIGS. 2C and 2D). Reference numeral 28). In the case of FIG. 2 (C), strip-shaped segments are formed, and in the case of FIG. 2 (D), rectangular segments are formed that are divided by virtual cuts obtained by extending cross cuts. Thus, the size and shape of the segment can be set as appropriate.

  “Structures” include those that are fixed at installation locations such as bridges, highways, railway overhead tracks, large tanks, large equipment, etc., and difficult to move. Including those that can be moved to maintenance places such as vehicles. In this pretreatment, various machine tools (for example, a blade, a laser processing machine, an electric discharge machine, etc.) can be used.

  After the pretreatment, the laser irradiation apparatus (1 to 4) is then used to irradiate the coating film in the region including the cuts or segments with the laser 30 to peel at least a part of the coating film (hereinafter referred to as “peeling process”). "). In addition, a region including a cut or a segment that has been subjected to pretreatment and is a surface region to be subjected to a peeling treatment is referred to as a “peeling treatment region”.

  In this coating film removing method, the coating film can be peeled for each segment depending on the laser irradiation conditions, the coating film mode, the surface mode, and the like. For example, in a thick coating film having a thickness of about 1.0 mm, the coating film could be peeled segment by segment at a relatively severely deteriorated portion. Peeling for each segment includes not only peeling by a single segment along the cut made in the pretreatment but also peeling by a segment group consisting of a plurality of segments. Furthermore, depending on the shape and size of the segment or the laser irradiation conditions, the coating film may be separated into smaller pieces than the segment. In this coating film removing method, if necessary, using a suction device (7 to 9), a removed product (including the generated gas, smoke, dust, etc. in addition to the coating film peeled off from the surface 20)). Aspiration and collection may be performed.

  Moreover, you may perform the process (henceforth an "acceleration process") for accelerating | stimulating peeling of a coating film simultaneously or after a peeling process. In the acceleration treatment, for example, vibration is applied to the separation treatment area of the structure by an ultrasonic generator or the like, a physical impact is imparted by a brush or the like, or a fluid such as water or air is ejected. The impact can be applied and the peeling of the coating film can be promoted.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following examples.

[Preprocessing]
In the present invention, first, as a pretreatment, a notch having a predetermined depth (see, for example, symbol d in FIG. 3) is formed in the coating film. Segments may be formed by these cuts. In the example of FIG. 1, the rectangular segment is formed by forming a grid-like cut, but the present invention is not limited to this.

Segments in coating film mode (type of coating film, thickness, ratio of deteriorated layer and active film layer, etc.), surface mode (degree of curvature, type of base material under coating film, etc.), and peeling treatment Depending on the laser irradiation conditions (energy density, focal position, beam width, scanning shape, etc.), an arbitrary shape combining at least one of a straight line and a curved line may be set. Moreover, although it is based also on the aspect of the said coating film, etc., it is preferable to form a notch so that each segment may become an area of the range of about 9-2500 mm < ² >.

  FIG. 2 is an example of notches and segment shapes formed in the coating film in the pretreatment. FIG. 2A is an example in which rhombic segments are formed by combining oblique straight cuts. FIG. 5B is an example in which a fan-shaped segment is formed by forming a plurality of concentric cuts and radial straight cuts around a protrusion 90 (for example, a bolt) on the surface 20. . In some cases, a cut that does not form a closed region may be made. FIG. 6C shows an example in which a plurality of linear cuts are arranged in a certain direction to form a strip shape. FIG. 4D shows an example in which a plurality of cross-shaped cuts are arranged. In addition, the notch | incision or the shape of a segment of the figure is only an example, Comprising: Various deformation | transformation are possible.

  FIG. 3 is an example of the cross-sectional shape of the cut formed in the coating film in the pretreatment. As shown in FIG. 2A, when the notch 23 having a predetermined depth d is formed in the pretreatment, a plurality of segments 28 are formed in the coating film 22 by the notch 23. The predetermined depth d can be set as appropriate. For example, the predetermined depth d is preferably 2/3 or more of the thickness of the coating film. According to the present coating film removal method, at least a part of the coating film in the peeling treatment region can be removed or completely removed in the subsequent peeling treatment. This coating film removing method is preferably applied, for example, to the removal of a coating film having a thickness of 0.3 mm or more, and particularly applicable to the removal of a coating film having a thickness of 1.0 mm or more.

  By the way, as shown to the same figure (B), a coating film may contain the layer from which several (at least 2 or more) property differs. For example, the upper layer 24 on the surface side is a paint layer, and the lower layer 26 on the steel material base side is a coating layer made of a rust inhibitor, a base treatment agent, a resin, a polymer protective film, or the like. In some cases, the paint layer may have a laminated structure by applying the paint repeatedly during application, and after several years after application, the paint layer is further overcoated from the top of the paint layer as a repair work. Thus, there may be a laminated structure of paint layers having different properties. For example, the coating film 22 formed on the base material (steel substrate) 21 of the structure may include a deteriorated layer as the upper layer 24 and an active film layer as the lower layer 26 depending on the state of deterioration over time. The deteriorated layer is a layer on the surface side that has been deteriorated by outside air or ultraviolet rays and is losing adhesive force. The active film layer is a layer on the steel material base side where a sufficient adhesion force remains. The ratio between the deteriorated layer and the active film layer varies depending on the degree of deterioration over time, and the portion corresponding to the active film layer does not remain, that is, when all of the coating film 22 is a deteriorated layer. is there.

  The upper layer 24 and the lower layer 26 can be distinguished by contact or non-contact inspection means based on the difference in properties (water content, impedance, dielectric constant, magnetic permeability, etc.). For example, means for measuring the impedance of a coating film by contacting an electrode, electromagnetic induction type, eddy current type or ultrasonic type measurement means, measurement means using a terahertz electromagnetic wave pulse or a near infrared ultrashort pulse laser, which will be described later Each layer can be identified using various sensors and a combination thereof.

  Further, the deterioration layer and the active film layer can be distinguished depending on whether or not they have an adhesive force required as a paint for the structure. The required adhesion force varies depending on the structure, the purpose of the paint, the environment, etc., and is determined by the use of each structure. The degree of adhesion may be determined by, for example, a tape peel test, a cross cut test, or the like. In general, when the coating film deteriorates, the molecular structure in the coating film is destroyed, and moisture easily penetrates. For this reason, the amount of moisture may be measured using the impedance measuring means described above, and the measured result may be compared with a predetermined reference value to distinguish the deteriorated layer and the active film layer in the coating film. In addition, a system that evaluates deterioration phenomena of rust, crack (coating film) and peeling (coating peeling) from image information on the surface of the coating film has been proposed (“Steel Bridge Coating Film Degradation System” (Ishikawajima Harima) Technical Report Vol. 44 No. 1 (2004-1) pages 34-37), the degree of deterioration of the coating film is measured by such a system, and the measured result is compared with a predetermined reference value. The deteriorated layer and the active film layer may be distinguished.

  The predetermined depth d can be set as appropriate, but is desirably 2/3 or more of the thickness corresponding to the upper layer (for example, a deteriorated layer) or the entire thickness of the coating film 22. In the example shown in FIG. 5B, the predetermined depth d is described so as to correspond to the thickness of the deteriorated layer, but is not limited thereto. The depth of the cut may be shallower or deeper than the thickness of the deteriorated layer. Moreover, you may make the notch | incision of the depth which reaches the steel material base 21. FIG. In the subsequent peeling process, it is preferable to set the predetermined depth d so that energy by laser irradiation is efficiently transmitted by cutting.

  When the coating film on the surface of the structure is repainted, if a method of forming a new coating film after completely removing the coating film on the steel material base is adopted, a great deal of cost and working time are required. On the other hand, if the method of overcoating the new coating after removing only the judged part that has been visually deteriorated is not removed completely, the cost and labor can be reduced. it can. However, in the latter case, the new overcoated film sometimes peeled off with a deteriorated portion that could not be visually determined within a few years after repainting.

  In this coating film removal method, the coating film (active film layer and deteriorated layer) can be completely removed, but in one embodiment of this coating film removal method, at least the upper layer (degraded layer) of the coating film is efficiently peeled off. You can also That is, since at least a part of the lower layer (coating layer or active film layer) can be left, application of the present coating film removing method is preferable for the above problems.

[Peeling treatment]
After carrying out the pretreatment, the coating film 22 in the peeling treatment region is irradiated with a laser in an appropriate scanning shape by a laser irradiation device to be described later. It is considered that the energy by laser irradiation propagates not only from the surface of the coating film but also from notches in the region irradiated with laser. Thereby, at least a part of the coating film is efficiently peeled off. Further, although depending on the form of the coating film, the shape and depth of the cut, and the laser irradiation conditions, the deteriorated layer can be peeled while at least a part of the active film layer remains in the coating film.

  The scanning shape of the laser may be, for example, a circle or an annulus, although it depends on the relationship with the shape or size of the segment. Alternatively, a planar shape in which the locus of a circle or ring is continuous and the laser irradiation energy is distributed substantially uniformly within a certain range may be used. After the peeling process, the removed product may be sucked and collected by a suitable suction means.

[Laser irradiation equipment]
Hereinafter, the laser irradiation apparatus used for peeling treatment (or pretreatment and acceleration treatment) will be described. FIG. 1 shows a schematic configuration of a laser irradiation apparatus used in the coating film removing method of the present invention. This laser irradiation apparatus is configured such that irradiation conditions such as laser output, focal position, beam width, scanning shape (pattern), and scanning speed can be appropriately set according to the type and nature of the surface.

  The laser irradiation apparatus includes a laser oscillator 1 and a laser head 3 connected to the laser oscillator 1 via a fiber 2. The laser head 3 includes a scanning optical system 4 for scanning an irradiation point of the laser, and is configured to be able to irradiate the surface 20 of the structure with the laser. The laser head 3 is preferably small, light, and portable so that the operator can operate it at the work place. The housing of the laser head is preferably configured in a small shape with excellent grip so that the operator can easily grip it.

  Moreover, in this embodiment, you may use the suction device which sucks a removal thing as needed. The suction device includes a suction means (nozzle) 7, a suction hose 8, and a suction source 9. The laser oscillator 1 and the suction source 9 are preferably devices configured to be transportable and movable, and may be mounted on various vehicles 100 (including carts, vehicles, trolleys, monoracks, monorails, conveyors, etc.). Good.

The laser oscillator 1 includes an excitation source, a laser medium, an optical resonator (mirror), and the like. The excitation source may be either a continuous oscillation (CW) type or a pulse oscillation type, and an arc lamp, a flash lamp, or the like can be used. Moreover, you may provide the drive means for adding an excitation current etc. and driving according to the light source to be used. The laser medium is preferably a solid laser (ruby laser, YAG laser, etc.) or a semiconductor laser (laser diode). In particular, it is preferable to use a fiber laser as the solid laser. The laser medium is not particularly limited, and a gas laser (CO ₂ laser, excimer laser, etc.), a liquid laser (dye laser), or the like may be employed. The laser output from the laser oscillator 1 is transmitted to the laser head 3 through the transmission fiber 2.

  In this coating film removing method, the laser oscillator 1 itself is transported to the vicinity of the surface (working place) of the structure, and the surface is irradiated with a laser by a laser head 3 that can be handled while moving appropriately, thereby removing the coating film. Can be implemented. The laser oscillator 1 itself may be disposed within the reach of the fiber 2.

  The purpose of this laser irradiation device is not to drill holes in the workpiece, but to remove the surface coating or to form cuts in the surface coating. Even if it is not obtained, it is sufficient that the coating film can be removed by laser irradiation a plurality of times or an energy density sufficient to cut the coating film can be obtained. Therefore, a low-power laser oscillator can be used in this process. However, a high-power laser oscillator may be used so that a large energy density can be obtained by a single laser irradiation.

  Further, either a CW type laser or a pulse type laser may be selected depending on the structure to be processed, the type of coating film, the overall configuration of the apparatus, and the like. In particular, the CW type laser requires a larger electric power than the pulse type laser to obtain a desired irradiation energy, but is preferable because it is low in cost. Further, according to the present inventors, it was confirmed that the surface after removal of the coating film was smoother with the CW type laser than with the pulse type laser in laser irradiation per unit time and unit area. Thus, it is preferable to employ a CW type laser because the coating process after the coating film removal may be facilitated. However, the present embodiment is not limited to the CW type laser, and either the CW type laser or the pulse type laser is selected according to the target structure, type of coating film, overall configuration of the apparatus, etc. Also good.

  The laser head 3 is a device that irradiates the surface 20 of the structure with the laser output from the laser oscillator 1 and transmitted through the fiber 2 and removes the coating film on the surface 20. The laser head itself can be handled at the work place. The laser head 3 can appropriately set the intensity of laser irradiation and the like by changing the output of the laser oscillator 1. Further, the laser head 3 is configured such that the scanning optical system 4 can appropriately set irradiation conditions such as a focal position, a beam width, and a scanning shape according to the structure and surface state and properties.

In the peeling process, the laser 30 irradiated from the laser head 3 preferably has an output of 100 to 2000 W and a wavelength of 500 nm or more, and particularly preferably has an output of 500 to 1000 W and a wavelength of 1060 to 1100 nm. The energy density per unit time at the focal point can be appropriately designed according to the surface material, state and irradiation time, but it is 3.13 × 10 ⁻⁴ to 1 × 10 ⁻³ J / μm ² . It is preferable to be in the range. The laser spot diameter may be set as appropriate in relation to the energy density and the dimension of the workpiece, but is preferably in the range of 20 to 200 μm in diameter.

  The scanning optical system 4 is composed of, for example, a combination of a condensing element, a reflecting element, a refracting element, a driving unit, and the like. The irradiation point of the laser 30 on the surface 20 can be scanned linearly or curvedly. Although an appropriate configuration can be adopted for the scanning optical system 4, it is preferable to use a configuration in which the laser is deflected using a transmissive refracting element in order to make the laser head small and simple.

  The suction means 7 sucks the removed material generated from the laser irradiation point by the negative pressure applied by the suction source 9. The suction source 9 is, for example, a pump that applies a suction force, and may include a processing chamber that processes the suctioned removed material, an exhaust filter, and the like. The removed matter sucked from the suction means 7 may be collected by the suction source 9 via the suction hose 8, and the other harmless air may be discharged via the exhaust filter. The fiber 2, the suction hose 8, the power cable (not shown), and the like may be bundled into one cable so that the operator can easily handle the laser head 3 at the work place.

  In the peeling process, if the removed material enters the laser head 3 and adheres to the optical system, the optical system may be damaged. For this reason, it is preferable to blow away the removed material in an appropriate direction or to guide the suction means 7 using an appropriate fluid spraying means (not shown). Moreover, you may provide the shielding means (for example, code | symbol 48 of FIG. 4) for preventing a removal thing adhering to an optical system.

  The fluid spraying unit includes, for example, a nozzle that sprays fluid, a fluid supply source, a supply hose, and the like. The nozzle can be disposed at an appropriate position, and may be disposed inside or outside of the laser head 3. Alternatively, the nozzle may be separated from the laser head 3 in a direction different from the optical axis direction of the laser head. You may comprise so that it may spray with respect to all or one part of peeling process area | regions. Alternatively, the laser head 3 may be filled with a gas having a pressure higher than that of the outside air so that the removed material does not enter the laser head.

  The fluid supply source pumps fluid to the nozzle via a supply hose. The fluid supply source includes, for example, a tank, a cylinder, and a compressor, and may be mounted on the vehicle 100 together with the laser oscillator 1 and the suction source 9. Moreover, if it is set as the structure provided with a some nozzle and a some fluid supply source, the fluid of a different kind and a different pressure can also be separately supplied to all or one part of the peeling process area | region from a different direction. For this reason, this fluid spraying means can be used also for the acceleration process mentioned later.

  As the fluid, it is possible to select at least one of an appropriate gas and liquid according to the working environment and the state of the processing surface. As this gas, dry air, nitrogen, carbon dioxide, inert gas (for example, helium, neon, argon, etc.), and vapor can be appropriately selected. In particular, when there is a possibility of generating a toxic reaction gas (for example, chlorine) from the treatment surface, it is preferable to supply nitrogen or an inert gas in order to reduce these generations. As the liquid (including mist (steam)), chemicals such as water (including hot water), a processing agent for promoting peeling, and a base protecting agent after removing the coating film can be selected.

  If such fluid spraying means is used, the laser head can be protected not only from the peeled coating film but also from dust, minute fragments, smoke and the like generated from the treated surface. Moreover, the peeled coating film etc. can be guide | induced to the direction of the suction means 7 efficiently.

  Moreover, for the acceleration process described later, the present laser irradiation apparatus may include an acceleration unit that applies physical force to the peeling process region on the structure surface to promote peeling. Specifically, as the promoting means, in addition to the fluid spraying means, means for irradiating the peeling treatment area with ultrasonic waves, heat, etc. (ultrasonic irradiation device, ultrasonic heater, heater, etc.), vibration Means for direct transmission (vibration generator), scraper for scraping off the membrane, brush, roller, adhesive tape, etc., or some combination of these can be used. In addition, the laser head may have an attachment at the tip thereof, or a hood that covers at least a part of the casing, and may be configured to be able to contact the peeling treatment region. Then, physical force (vibration, impact, etc.) may be directly applied to the surface of the peeling process via this attachment or hood (provided with a brush or the like at the contact portion with the peeling process area).

  Further, the laser irradiation apparatus may include a control unit (not shown). The control unit has a function of controlling the scanning mechanism, variable focus mechanism, suction device, and the like of the scanning optical system 4. The control unit may be configured to realize various processes by cooperating hardware and a program, or may be configured by a dedicated processing circuit. The control unit may be provided in the laser head main body, or may be provided separately from the laser head main body. For example, a terminal connected wirelessly or by wire may be used as a control unit, which may control the laser head 3.

  Further, the laser irradiation apparatus may include an operation unit (not shown). The operation unit has a function of receiving the operation from the worker and outputting the operation content to the control unit. Moreover, you may have a function which displays the operation result, the coating-film removal condition, a laser parameter, etc. The operation unit includes, for example, various switches, knobs, a software keyboard, a display device, and the like.

  Furthermore, the laser irradiation apparatus may include various sensors (for example, a surface state sensor, a monitoring sensor, a surface-to-surface distance measurement sensor, etc.) according to the purpose. The surface condition sensor (not shown) includes the base material of the surface 20 (steel plate, aluminum, etc.), the state of the coating film (floating, thickness, ratio of deteriorated layer and active film layer), rust state (area, degree), It can detect corrosive substances, dirt, and the state of adhesion of oils and fats. Specifically, a radiation temperature sensor, a visible spectral image sensor, a near infrared camera, a general camera, or the like can be employed.

  The surface state sensor may detect the material of the base, the state of the coating film, the state of rust, the corrosive substance, the dirt, the state of adhesion of oil and the like, and notify the control unit or the like. Moreover, when employ | adopting a general camera as a surface state sensor, the said camera image | photographs the coating-film surface, You may pass the image information to a control part (an image processing means is included). The image processing means extracts a deteriorated portion (for example, rust, crack, peeled portion) in the acquired image information by various image processing (binarization processing, density morphology processing, etc.), and the area ratio of the deteriorated portion to the image May be calculated to determine the degree of progress of the coating film deterioration. Moreover, you may distinguish the deterioration layer and active film layer in the coating film of the object surface according to this determination result. By these, it is possible to determine the depth of cut in the “pretreatment” or the laser irradiation conditions in the “peeling treatment”.

  The monitoring sensor (not shown) is, for example, a CCD camera or a CMOS camera. The inter-surface distance measurement sensor (not shown) is a sensor that measures the distance to the surface with infrared rays or the like. The control unit can set the focal point at a position suitable for removing the coating film based on the distance between the surfaces detected by the sensor. Specifically, the variable focus mechanism of the optical system can be controlled so that the focal length of the laser is equal to or longer than the measured distance between the surfaces.

  When the pre-treated coating film is irradiated with a laser using the above laser irradiation apparatus, the region receiving energy by laser irradiation becomes a high temperature and high pressure state and ablation (transpiration) occurs. It is considered that heat or the like due to this laser ablation propagates not only from the surface of the coating film in the irradiation region but also from notches in the irradiation region. By this action, all the layers of the coating film or at least a part of the layers (deteriorated layer) are efficiently removed. Moreover, depending on the laser irradiation conditions and the mode of the coating film, at least a part of the coating film may be peeled off in segment units along the cuts made by the pretreatment.

  Thus, in the present invention, at least a part (for example, a deteriorated layer) of a thick coating film can be efficiently peeled, and another part of the layer (for example, an active film layer) can be left. For this reason, the cost required for repainting and repairing the structure can be greatly reduced.

  In addition, according to the transportable and movable laser irradiation apparatus of the present invention, at least a part of the coating film on the surface can be peeled off at the work place, and the removed material can be collected as necessary. In addition, since a portable laser head that can be routed and connected to a laser oscillator via a fiber is used, an operator can easily remove the coating film.

  Hereinafter, the specific structure inside the laser head of the laser irradiation apparatus used for this coating film removal method is demonstrated. The scanning optical system inside the laser head may employ a wedge prism that can rotate around the optical axis and a rotation driving means that rotates the wedge prism (example of the first scanning optical system). According to this, it is possible to irradiate the laser so as to have a conical shape with a wider tip. When the target surface area is generally flat and the optical axis is substantially perpendicular to the surface, the continuous trajectory of the laser irradiation point on the surface is centered on the intersection of the optical axis and the surface. The wedge prism has a circular shape with the radius of deflection. Here, scanning the laser irradiation point in a circle is referred to as “circular scanning” in contrast to the conventional linear scanning. An operator can remove a specific range or a wide range of coating efficiently in a short time by holding this laser head for a certain period of time or by reciprocating up and down or left and right as required. Can do.

  In addition, the scanning optical system of the laser head may employ a first wedge prism and a second wedge prism that can rotate around the optical axis, and the laser is conically shaped with a widened tip (may be partially hollow). (Example of second scanning optical system). According to this, the continuous trajectory of the laser irradiation point on the surface is the deflection of the second wedge prism with the moving point on the circumference of the first circle having the radius of the deflection amount of the first wedge prism as the center. A second circle having a radius as the amount is continuously rolled. If the laser irradiation point is continuously scanned for a certain time while the optical axis is fixed with respect to the surface, the continuous trajectory can be regarded as a ring or a plane of a circle. However, the present invention is not limited to the following examples.

[Example of first scanning optical system]
In the first example, as the scanning optical system, a wedge prism that can rotate around the optical axis and a driving means that rotates the wedge prism are used, and the laser is irradiated onto the conical shape (side surface) that has been expanded. The continuous trajectory of the laser irradiation point on the surface is a circle C1 centered on the intersection of the optical axis and the surface and the deflection amount of the wedge prism being a radius r1.

  In the peeling process, the operator may hold the laser head for a certain period of time and scan the laser in a circular pattern with respect to the coating film, or reciprocate the laser head vertically or horizontally as necessary. Thus, the laser may be irradiated substantially uniformly on the coating film.

  FIG. 4 is a schematic configuration diagram of a first example of the scanning optical system. The scanning optical system 4 </ b> A includes a fiber connection portion 41, a condensing unit 42, a first wedge prism 43, a support member 44, and a driving unit 49.

  The fiber connection portion 41 is an optical element (laser emission collimator (for example, quartz lens)) attached to the emission end of the fiber 2, and directs the laser beam transmitted through the fiber 2 toward the condensing means 42. To be emitted.

  The condensing means 42 is a condensing optical system composed of one or a plurality of lenses, condenses the laser output from the fiber connection portion 41 to a high energy density, and irradiates the surface 20 as the laser 30. . The condensing unit 42 can appropriately set the focal length, the focal depth, and the beam spot diameter of the laser 30.

  The first wedge prism 43 is an optical element that deflects an incident laser at a deflection angle θ with respect to the optical axis L. The first wedge prism 43 (and the condensing means 42) are supported by the support member 44. In this example, a wedge prism is employed as an optical member for deflecting the optical path of the laser. As a result, the optical path of the laser becomes simple without repeating reflection, compared with the case where an optical member such as a galvano mirror is used, so that the configuration of the laser head can be made small and simple.

  The drive unit 49 rotates the first wedge prism 43 by rotating the support member 44 around the optical axis L at a predetermined rotation speed ω. The drive means 49 can employ an appropriate configuration such as a motor or a rotary actuator, but preferably employs a hollow motor that can be arranged around the optical axis in order to make the laser head small and simple. .

  According to the scanning optical system 4A, the irradiation point P (including the irradiation spot) of the laser 30 appears on the surface 20 at a distance r from the optical axis intersection point O. The distance r is a deflection amount based on the deflection angle θ of the first wedge prism 43 and the distance from the first wedge prism 43 to the surface 20.

  In addition, a shielding plate 48 that protects the first wedge prism 43 can be employed in order to shield the removed matter generated from the vicinity of the laser irradiation point. The shielding plate 48 is fixed to the first wedge prism 43 or the support member 44, is configured to be rotatable with the first wedge prism 43 or the support member 44, and has an opening through which the laser 30 deflected according to the deflection angle of the wedge prism passes. . As a result, the wedge prism can be protected from the removed material that peels off from the surface 20 and flies. Further, a conductive member may be provided on at least a part of the shielding plate 48 so as to positively remove a statically removed fine object. Further, as a countermeasure against static electricity, static electricity may be removed by supplying a gas containing ions in accordance with the charge amount of the removed matter.

  In this example, when removing the coating film, it is only necessary to give an energy density sufficient to remove the coating film by a plurality of circular scans. Therefore, conventional lasers for metal drilling, spot welding, etc. Unlike the processing apparatus, the focal point does not have to coincide with the actual irradiation point of the laser. In the circular scanning, the optical path length of the laser 30 is substantially the same at each point of the substantially circular locus. Therefore, unlike the case of the linear scanning, the distance between the focal point and the actual irradiation point is the same as that during the rotational scanning. It is possible to irradiate with a constant irradiation energy without changing. Further, in order to effectively use the energy of the laser, it is preferable to set the focal point position behind the surface (defocus to the minus side). Further, the depth of focus may be set to a certain degree. As a result, it is possible to remove the coating film even on the surface of a structure having a protrusion, a step, or a depth.

  FIG. 5 is an explanatory diagram showing the locus of the laser irradiation point according to the example of the first scanning optical system. When the optical axis L and the surface 20 are substantially perpendicular and the surface 20 is substantially flat without curvature or irregularities, the first wedge prism 43 rotates at the rotational speed ω around the optical axis L. The irradiation point P is a moving point that moves at the rotational speed ω on the circumference of a circle having a radius r centered on the optical axis intersection point O on the surface 20.

  In other words, the irradiation point P describes a locus of a circle C (including a substantially circular shape) having a radius r centered on the optical axis intersection point O. Therefore, when the laser 30 is irradiated on the peeling treatment region using the scanning optical system 4A, energy is applied to the coating film along the circumference of the circle C on the surface 20. It is considered that the energy due to laser irradiation propagates not only from the surface of the coating film but also from notches in the irradiation region, so that the coating film can be efficiently removed. In order to simplify the description, the circumference of the circle C is represented as a line having no width in the figure, but in reality, the laser 30 has a spot diameter width. The radius r is preferably set to be 5 to 200 mm.

  When the laser head 3 is moved in a vertical direction or a horizontal direction at a constant speed in parallel with the surface 20 while performing circular scanning like the shape of the circle C, or by an operator's operation, The locus of P is substantially band-shaped. In this case, since the irradiation point P is scanned substantially uniformly with respect to the surface 20, it is possible to irradiate the coating film in the peeling treatment region substantially uniformly. In this case, the coating film may be peeled off in segment units or smaller units along the cuts made in the pretreatment, or in segment groups.

  In the figure, in order to simplify the description, a shape in which a circle C continues in the moving direction of the laser head is schematically shown. However, in actuality, the irradiation point is scanned in a circular shape while moving the laser head (that is, the intersection of the optical axes), and therefore the locus of the irradiation point P is not continuous with the circle C, which is a closed curve, but is an open curve. It becomes a shape like a coil. More precisely, the locus of the irradiation point P is the locus of the end point of the radial vector r that rotates at the rotational speed ω.

  Specifically, for example, when the irradiation point P is on the Y-axis at the time t = 0 and rotation starts at the angular velocity ω (circular scanning only), the locus (Px, Py) of the irradiation point at the time t ) Is represented by the following equation.

Px = rsinωt
Py = rcos ωt
Further, for example, when the operator moves the laser head in the direction of a vector having an angle φ with respect to the X axis at a constant speed V, the locus (Px, Py) of the irradiation point at time t is as follows: It is expressed by a formula.

Px = rsinωt + Vtcosφ
Py = rcosωt + Vtsinφ
In particular, when the laser head is moved in the horizontal direction (X-axis direction), the following occurs.

Px = rsin ωt + Vt
Py = rcos ωt
The figure shows a case where the optical axis L and the surface 20 are substantially perpendicular, the surface 20 is flat, and the locus of the irradiation point P is substantially circular. When the laser head is held tilted with respect to the surface normal (that is, when the optical axis L and the surface 20 are not substantially perpendicular), the locus of the irradiation point P is an ellipse (including a substantially elliptical shape). Become.

  When the surface 20 is uneven or has a curvature, the locus of the irradiation point P becomes a distorted circle or ellipse. When the locus of the irradiation point P is elliptical, strictly speaking, the optical path lengths of the lasers at the respective irradiation points on the locus are different from each other, and the preset focal point may deviate from a desired position. . In this case, it is preferable to set the depth of focus to a certain extent in advance (the range of the change amount of the optical path length). According to the plurality of rotation scans, a desired energy density for removing the coating film can be accumulated, so that there is no problem even if the optical path length changes to some extent.

  As described above, according to the scanning optical system of the present example, the laser irradiation point is rotationally scanned in a circle around the optical axis intersection point, so that a substantially planar scan can be obtained by appropriately moving the laser head. In addition, the coating film can be irradiated with laser substantially uniformly.

  In addition, since a wedge prism is used as a scanning element for deflecting the optical path of the laser, the optical path of the laser is simple and repeats less than when an optical element such as a galvanometer mirror is used. It can be small and simple. As a result, a small laser head that can be handled at the work place can be realized at low cost. Further, in such circular scanning, the optical path length does not change, so that the configuration of the laser head can be simplified.

  Further, the depth of focus may be set to be large to some extent, which makes it possible to remove the coating film on the projections, the steps, the surface of the deep structure, and the corners of the structure. Moreover, the required energy density for laser ablation can be given by multiple times of circular scanning, and energy can be efficiently given to the coating film. Further, according to such circular scanning, even if the laser is reflected from the surface, there is no possibility that the return light enters the laser head and damages the fiber 2.

[Example of Second Scanning Optical System]
In the first example, one wedge prism is used for the scanning optical system. On the other hand, in the second example, a wedge prism that can rotate around the optical axis and a deflecting unit are used as the scanning optical system, and the laser is conically shaped like a tip (partially hollow). ). The deflecting unit may be a reflective optical element such as a mirror, but preferably employs a transmissive optical element such as a wedge prism. Hereinafter, a case where a wedge prism is used as the deflection unit will be described. The continuous trajectory of the laser irradiation point on the surface is the second centered on the moving point on the circumference of the first circle whose radius is the deflection amount of the first wedge prism (first wedge prism). The second circle whose radius is the deflection amount of the wedge prism (second wedge prism) is a shape that rolls continuously. If the laser irradiation point is continuously scanned for a certain period of time while the optical axis is fixed with respect to the surface, the continuous trajectory can be regarded as a ring or a plane of a circle. Irradiation is possible.

  FIG. 6 is a schematic configuration diagram of an example of the second scanning optical system. The scanning optical system 4B includes a second wedge prism 45, a support member 46, and a transmission unit 47 as an additional configuration to the first example. In this example, the same components as those in the first example are denoted by the same reference numerals, and detailed description thereof is omitted.

  The second wedge prism 45 further passes the laser optical path with respect to the laser optical path M (hereinafter also referred to as the rotation reference axis M) deflected by the first wedge prism 43 with the deflection angle θ1 with respect to the optical axis L. Deflection is performed with a deflection angle θ2. The second wedge prism 45 is supported by the support member 46.

  The transmission unit 47 connects the support member 44 including the first wedge prism 43 and the support member 46 including the second wedge prism 45, and transmits the driving force from the driving unit 49. As the driving means 49, for example, a gear mechanism capable of setting an appropriate rotation ratio can be used.

  In this example, the driving member 49 rotates the support member 44 around the optical axis L, thereby rotating the first wedge prism 45 at the rotational speed ω1 and further via the transmission means 47 connected to the support member 46. By rotating the support member 46 about the optical axis L, the second wedge prism 45 is rotated at the rotational speed ω2.

  Further, when considering the surface 20 substantially perpendicular to the optical axis L, when the two wedge prisms are rotated around the optical axis L, the intersection Q between the surface 20 and the rotation reference axis M becomes the optical axis intersection O. Appears on the surface at a distance r1. An irradiation point R (including an irradiation spot) appears at a distance r2 on the surface from the intersection Q.

  The distance r1 is a deflection amount based on the deflection angle θ1 of the first wedge prism 43 and the distance from the first wedge prism 43 to the surface 20, and the distance r2 is the deflection angle θ2 of the second wedge prism 45 and the first angle. 2 A deflection amount based on the distance from the wedge prism 45 to the surface 20.

  In the figure, the configuration in which the driving unit 49 directly applies the rotational driving force to the first wedge prism 43 and the transmission unit 47 indirectly applies the rotational driving force by the driving unit 49 to the second wedge prism 45 has been described. However, the present invention is not limited to this. Different rotational driving forces may be separately applied to each wedge prism by the two driving means, or a rotational driving force applied directly from the driving means to the transmission means may be applied to each wedge prism. Any configuration is possible as long as the first wedge prism 43 and the second wedge prism 45 can rotate at different rotational speeds.

  FIGS. 7A and 7B are explanatory views showing the locus of the laser irradiation point according to the example of the second scanning optical system. FIG. 4A is a trajectory while the first wedge prism makes one round, and FIG. 4B is a trajectory when the first wedge prism rotates a plurality of times. In each figure, the optical axis L and the surface 20 are substantially perpendicular, and the surface 20 is a substantially flat surface having no curvature or unevenness.

  In FIG. 5A, the rotation reference axis M is a moving radius that rotates around the optical axis L at the rotation speed ω1, and therefore the intersection point Q between the rotation reference axis M and the surface 20 is centered on the optical axis intersection point O. The moving point moves on the circumference of the circle C1 having the radius r1 at the rotational speed ω1 (hereinafter also referred to as the moving point Q). The laser irradiation point R is a moving point that moves at a rotational speed ω2 on the circumference of a circle C2 having a radius r2 centered on the moving point Q.

  In the figure, for explanation, the locus of the circle C2 when the rotation reference axis M makes a round, that is, when the moving point Q on the circle C1 makes a round, is schematically shown. C2 has a continuous shape centered on each point on the circle C1. However, in practice, the moving point Q moves on the circle C1, and the irradiation point R moves around the circle C1, so that the locus of the irradiation point R is not continuous with the individual circles C2 that are closed curves. The shape is like a ring of a coil that is an open curve. More precisely, the trajectory of the irradiation point R is the trajectory of the end point of the radial vector r2 that further rotates at the rotational speed ω2 around the end point of the radial vector r1 that rotates about the optical axis intersection O at the rotational speed ω1 ( That is, the locus of the end point of the vector r (r1 + r2).

  The rotational speed ω2 is preferably set sufficiently higher than the rotational speed ω1, and the ratio of the rotational speed ω1 and the rotational speed ω2 (rotational ratio ω2 / ω1) is preferably at least greater than 9/2.

  Furthermore, it is preferable to set the rotation ratio (ω2 / ω1) so that the initial position of the irradiation point R does not coincide with the position of the irradiation point R when the rotation reference axis M makes one or several turns. Then, even if the rotation reference axis M rotates several times, C2 which is the locus of the irradiation point R does not overlap on the surface 20, so that substantially uniform scanning is possible.

  Further, when the scanning optical system 4B (laser head) is moved parallel to the surface 20 at a constant speed in the vertical and horizontal directions while scanning the shape of the circle C2, automatically or by the operator's operation. The irradiation point R can be scanned substantially uniformly with respect to a specific range of the surface 20, and energy can be efficiently applied to a wide range of the coating film on the surface 20.

  In FIG. 5B, since the scanning of the shape of the circle C2 is performed without moving the optical axis intersection point O for a certain period of time, the set of irradiation points becomes a region of an annulus C3 having the circle C1 as a central curve, The region of the ring C3 is irradiated with the laser substantially uniformly.

  Thus, according to this example, in addition to the effect of the first example, the laser irradiation point is scanned with an annular or circular surface, so even if the laser head is fixed to the surface of the structure, The coating film can be irradiated with laser substantially uniformly. In this case, at least a part of the coating film may be peeled off by a unit of segment or a smaller unit of fragments or a group of segments by the energy transmitted from the coating film surface and the cut. Further, since the radius of the center curve C1 and the width of the ring C3 depend on r1 and r2 corresponding to the deflection amount by each wedge prism, r1 and r2, that is, the deflection angle θ1 of the first wedge prism and By appropriately setting the deflection angle θ2 of the second wedge prism, it is possible to set an irradiation area of an annular of various sizes and shapes. It is also possible to set a circular shape without an irradiation area at the center.

  For example, when the coating film around a circular projection on the processing plane is peeled off, irradiation is performed with the deflection angle θ1 and the deflection angle θ2 set so that | r2-r1 | becomes the radius of the circular projection. If an area is provided, only the periphery of the circular protrusion can be scanned substantially uniformly. Further, if r2 ≧ r1 is set, it is possible to scan not in an annular shape but in a shape of the entire surface of the circle having no irradiation area in the center.

  As described above, when the laser irradiation apparatus provided with the scanning optical system according to the first and second examples is used in the peeling process, the coating film can be irradiated with a laser beam over a wide range. Due to the cuts, at least a part of the coating film can be easily and efficiently peeled off.

  In the first or second example, the mode in which the laser irradiation point is scanned in a circular shape has been described. However, in this scanning optical system, the wedge prism is not rotated and the laser is fixed in a circular shape. Irradiation can be performed without scanning in the shape. Therefore, the laser irradiation apparatus according to the first or second example can be used not only for the peeling process but also for the pretreatment. In this case, if the laser head itself is appropriately moved, or if the stage on which the processing target is placed is appropriately moved with respect to the laser head, an arbitrary cut of a straight line or a curved line can be formed in the coating film. You may change the output of a laser suitably according to the aspect of a coating film.

  Further, since the laser irradiation apparatus is configured so that the laser irradiation intensity, scanning shape, and the like can be set as appropriate, for example, when a part of the setting of the scanning optical system of the second example is changed, the laser irradiation apparatus is changed. It can also be used to perform a pretreatment to form a cut to a predetermined depth of the coating. The depth and shape of the cut can be arbitrarily set by appropriately setting the irradiation intensity of the laser, the number of scans, the scan shape, and the like.

In the pretreatment, the laser 30 irradiated from the laser head 3 preferably has an output of 100 to 2000 W and a wavelength of 500 nm or more, and particularly preferably has an output of 500 to 1000 W and a wavelength of 1060 to 1100 nm. The energy density per unit time at the focal point is preferably in the range of 3.13 × 10 ⁻⁴ to 1 × 10 ⁻³ J / μm ² . The spot diameter of the laser is preferably in the range of 20 to 200 μm. Thus, in the pretreatment of this coating film removing method, if the laser irradiation device used for the peeling treatment is used, the pretreatment and the peeling treatment can be carried out with the same device, so the cost and time required for the work Can be reduced.

[Example of third scanning optical system]
FIG. 8B is a schematic configuration diagram of an example of the third scanning optical system, and FIG. 8A is an explanatory diagram illustrating a locus of a laser irradiation point according to the third example. In the second example, the rotational speed ω2 of the second wedge prism 45 is set sufficiently higher than the rotational speed ω1 of the first wedge prism 43 (ω2 >> ω1). In this example, in the scanning optical system 4D, The rotational speed ω1 and the rotational speed ω2 are set so that the difference does not increase (ω2≈ω1). For example, the rotation ratio ω2 / ω1 can be set in the range of 9/10 to 11/10.

  Then, the deflection angle θ2 of the second wedge prism 45 is set to be sufficiently smaller than the deflection angle θ1 of the first wedge prism 43 so that r2 is sufficiently smaller than r1 (θ2 << θ1). As a result, as shown in FIG. 5A, the set of laser irradiation points becomes a ring with a sufficiently small width (for example, about 1 to 3 mm) defined by 2 × r2. For this reason, according to the present example, energy by a plurality of times of laser irradiation concentrates on the annular region, so that a substantially circular cut having a predetermined depth can be formed in the coating film. That is, it is possible to form a circular segment. In addition, the laser irradiation apparatus provided with the scanning optical system according to the present example can be applied to the peeling process if the laser irradiation conditions are appropriately set.

[Example of Fourth Scanning Optical System]
FIG. 9B is a schematic configuration diagram of an example of a fourth scanning optical system, and FIG. 9A is an explanatory diagram illustrating a locus of a laser irradiation point according to the fourth example. In the second or third example, a difference is provided between the rotational speed ω1 and the rotational speed ω2, but in this example, each rotational speed is set to be the same in the scanning optical system 4D. In this case, since the first wedge prism 43 and the second wedge prism 45 rotate together, the locus of the laser irradiation point is not a ring but a simple circle having no width. Further, in the scanning optical system 4D, the relative phase difference between the rotation surfaces of the first wedge prism and the second wedge prism (the reference point on the outer edge of the first wedge prism and the outer edge of the second wedge prism). The displacement with respect to the reference point may be set as appropriate. In this case, as shown in FIG. 6A, a circle trajectory from a circle C4 having a radius r1-r2 to a circle C5 having a radius r1 + r2 can be formed between the wedge prisms. If the distance is changed, the size of r1 or r2 can be changed, so that the diameter of the circle can be set arbitrarily. For this reason, according to this example, for example, circular cuts having various sizes can be formed on the coating film around the protrusion 90 on the surface 20. In addition, the laser irradiation apparatus provided with the scanning optical system according to the present example can be applied to the peeling process if the laser irradiation conditions are appropriately set.

[Fifth Example of Scanning Optical System]
FIG. 10B is a schematic configuration diagram of an example of the fifth scanning optical system, and FIG. 10A is an explanatory diagram illustrating a locus of a laser irradiation point according to the fifth example. In this example, in the scanning optical system 4E, the first wedge prism 43 and the second wedge prism 45 have the same shape, material, and characteristics, and are inclined so that the extension lines of the central axes thereof coincide with each other. The other flat circular surfaces are aligned so as to face each other. That is, the deflection angles of the wedge prisms have the same magnitude, but are different in sign from the optical axis.

  When the first wedge prism 43 and the second wedge prism 45 are rotated in the opposite direction at the same rotational speed, the irradiation point is the rotation of the first wedge prism 43 and the second wedge prism 45 while each prism makes a round. As shown in FIG. 4A, a closed circular locus is shown. The length of the closed ring in the longitudinal direction corresponds to 2 × r depending on the deflection angle of the wedge prism. When the distance from the exit surface to the plane of the scanning optical system is long to some extent, the annular locus can be regarded as a substantially straight line. That is, according to the optimal setting in this example, a straight cut having a predetermined depth can be formed in the coating film, and a segment having a shape combining straight lines can be formed. In the case of this example, it is necessary to reassemble the second wedge prism so that the flat surface of the second wedge prism faces the first wedge prism side. For this reason, it is preferable that the orientation of the second wedge prism can be easily exchanged or can be exchanged during the pretreatment and the peeling treatment. Alternatively, separate laser heads having different scanning optical system configurations may be prepared in advance, and the laser head itself to be used may be selected according to the work.

  As described above, when the laser irradiation apparatus including the scanning optical system according to the third and fourth examples is used in the preprocessing, a circular segment having a desired diameter can be generated. In particular, when there is a protrusion on the surface of the structure, a circular or annular segment having a desired diameter can be formed according to the size of the protrusion, and the coating film can be efficiently peeled off. it can. In addition, if a laser irradiation apparatus provided with the scanning optical system according to the fifth example is used in the pretreatment, it is possible to form a linear cut while the laser head is fixed. Thereby, a straight line and a cut of a curve can be combined, and segments of various shapes can be formed.

[Promotion processing]
In this coating film removal method, the laser irradiation conditions (irradiation energy, scanning shape, etc.) and the mode of the coating film (thickness, ratio of active film layer and deteriorated layer, etc.) are taken into consideration at the same time or after the peeling treatment. Acceleration treatment for accelerating the peeling of the coating film can also be performed.

  In the acceleration treatment, vibrations, impacts, and the like are applied to the coating film in the peeling treatment region by the various means described above. For example, when using a fluid spraying means, peeling may be promoted by applying a gas pressure from one direction or multiple directions to the coating film in the peeling treatment region. Further, for example, by applying a finely squeezed shot-like gas or liquid lump to the peeling treatment region, an appropriate vibration or impact may be applied to the coating film to promote peeling of the coating film. When irradiating ultrasonic waves, heat, etc. or using a vibration generator, apply ultrasonic waves, heat, or vibrations to multiple points in the peeling process area, or apply ultrasonic waves, heat, or vibrations evenly. Or may promote the peeling of the coating film. Furthermore, simultaneously with laser irradiation, a physical force (vibration, impact, etc.) is directly applied to the surface of the peeling process via an attachment or hood at the tip (provided with a brush or the like in contact with the peeling process area). May be. Further, some of these acceleration treatments may be used in combination. In addition to the various means provided in the laser irradiation device, the acceleration treatment uses various tools (hammer, scraper, etc.) as appropriate while the operator holding the laser head observes the state of peeling of the coating film. And you may carry out by hand. In this way, the coating film can be efficiently peeled by using the acceleration treatment together with the peeling treatment by laser irradiation.

  As described above, according to the present coating film removing method, after forming slits or segments of various shapes in the coating film by the pretreatment, and performing the peeling treatment by laser irradiation, a wide range of coating films can be efficiently processed. Can be removed. In addition, a part of the coating film can be peeled off. Further, in one aspect of the laser irradiation apparatus of the present invention, a pretreatment for forming various shapes of cuts or segments on the coating film by a simple setting change or an operation of an operator holding the laser head, and the coating film The peeling treatment for peeling off can be carried out continuously with one apparatus. Moreover, if a promotion process is used together, a coating film can be peeled more efficiently. For this reason, the cost of the equipment required for coating film removal can be reduced.

[Example]
Hereinafter, the Example of the coating-film removal method of this invention is described. A sample of a part of the structure having a coating film formed on the surface was prepared. Such a sample has a steel material having a thickness of about 10 to 20 mm as a base material, and a coating film having a thickness of about 1.0 to 1.2 mm is formed on the surface thereof. The coating film has deteriorated over time, and some rust is observed on the surface of the base material under the coating film.

First, the sample was pretreated. Specifically, using the laser irradiation apparatus of the present invention, a plurality of straight cuts are made in the vertical and horizontal directions at intervals of about 3 to 10 mm in width, and lattice segments (area about 9 to 100 mm ^2). ) Was formed. The power of the laser is about 200 W, and the linear scanning speed of the laser is about 20 mm / s. The depth of the cut is about 1.0 to 1.2 mm and reaches the base material. In this example, in order to remove a relatively thick coating film that has deteriorated over time, the area of the segment during the pretreatment is set to be relatively small. However, the present invention is not limited to this. The shape and area of the segment can be set as appropriate according to the state of the coating film, and the mode of laser irradiation can also be set as appropriate according to the mode of the segment.

And the peeling process was implemented with respect to the sample in which this segment was formed. Specifically, using the laser irradiation apparatus of the present invention, a laser beam of about 20 mm is applied to the peeling treatment area while irradiating a laser with an output of about 500 W in a circular form (rotation drive means 3000 RPM) with a diameter of about 14 mm. It was moved at a speed of / s (see FIG. 5). In this example, the 30 mm × 35 mm peeling treatment area (1050 mm ² ) could be peeled off in about 22 seconds. Moreover, compared with the normal coating film removal which does not implement pre-processing, there were few irradiation marks of the circular laser in the base material after a process, and it became a smooth finish.

DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Fiber 3 Laser head 4 Scanning optical system 20 Surface 23 Notch 28 Segment 30 Laser

Claims (17)

A method of removing a coating film on the surface of a structure,
Pretreatment to form a cut in the coating film;
A coating film removing method comprising: irradiating a coating film in a region including the cuts with a laser to remove at least a part of the coating film.   The coating film removing method according to claim 1, wherein in the pretreatment, a segment is formed by the cut including at least one of a straight line and a curved line. Film removal method according to claim 1 or 2, characterized in that the area of the segments is in the range of 9～2500Mm ^2.   The method for removing a coating film according to any one of claims 1 to 3, wherein at least a part of the layer of the coating film is left.   The method of removing a coating film according to any one of claims 1 to 4, wherein the coating film has a thickness of 0.3 mm or more.   6. The coating film removing method according to claim 1, further comprising an accelerating process for accelerating the peeling of the coating film in the region including the notch simultaneously with or after the peeling process.   The coating film removing method according to claim 6, wherein the accelerating treatment sprays fluid onto the coating film.   The coating film removing method according to claim 6 or 7, wherein the accelerating treatment applies a physical force to the coating film.   A laser irradiation apparatus comprising: a laser oscillator; a fiber that transmits a laser output from the laser oscillator; and a laser head that irradiates a laser transmitted through the fiber, wherein the laser head transmits the laser The at least one of the pretreatment and the peeling treatment is performed using a laser irradiation apparatus including a wedge prism that deflects with respect to an optical axis and a driving unit that rotates the wedge prism. The coating film removing method according to any one of 8.   A laser irradiation apparatus comprising: a laser oscillator; a fiber that transmits a laser output from the laser oscillator; and a laser head that irradiates a laser transmitted through the fiber, wherein the laser head transmits the laser A first wedge prism that deflects with respect to the optical axis; a second wedge prism that deflects the laser beam deflected by the first wedge prism further with respect to its optical path; and the first wedge prism and the second wedge prism. The coating film removing method according to any one of claims 1 to 8, wherein at least one of the pretreatment and the peeling treatment is performed using a laser irradiation device including a driving means for rotating.   By controlling the rotation direction and rotation speed of each wedge prism, and the distance between the wedge prisms and the phase difference in the rotation direction, the laser irradiation point is scanned linearly and curvedly to perform the preprocessing. The coating film removing method according to claim 10, wherein:   In the preprocessing, the first and second wedge prisms are rotated in substantially the same rotational speed in the same direction while changing the distance between the wedge prisms or the phase difference in the rotational direction. The method of removing a coating film according to claim 10, wherein a notch of a different circle or annulus is formed.   10. The coating film according to claim 9, wherein the first and second wedge prisms are rotated in opposite directions at substantially the same rotational speed to form a substantially linear cut in the pretreatment. Removal method.   The coating film removing method according to any one of claims 1 to 8, wherein a blade is used in the pretreatment. A laser oscillator, a fiber for transmitting a laser output from the laser oscillator, and a portable laser head for focusing the laser transmitted through the fiber and irradiating the coating film on the surface of the structure; A laser irradiation device including:
The laser head is
The scanning optical system includes a wedge prism that deflects the laser with respect to the optical axis, and a drive unit that rotates the wedge prism around the optical axis at a predetermined rotational speed and direction.
After the laser is scanned to form a cut in the coating film, the laser is applied to the coating film in a region including the cut in a circle to peel off at least a part of the coating film. Irradiation device.   The laser irradiation apparatus according to claim 15, further comprising a fluid spraying unit that sprays a fluid onto the coating film in the region including the cut.   17. The laser irradiation apparatus according to claim 15, wherein an attachment or a hood is provided at a tip of the laser head, and the attachment or the hood includes an accelerating unit for accelerating the peeling of the coating film.