JP7750754B2 - Pulse laser irradiation device - Google Patents

Description

The present invention relates to a pulsed laser irradiation device.

In recent years, replacement work (specific renewal work) has been carried out on the concrete decks placed on top of steel girders of road bridges and other bridges that have been in service for a long time. Furthermore, since many bridges in Japan have been in service for over 50 years, or are within the next few years, many bridges are in need of the above-mentioned concrete deck replacement work.

Generally, when replacing a bridge's concrete deck, the steel bridge girders placed underneath the existing deck are often reused without replacement if there are no strength or durability issues due to corrosion or other factors. In this case, after the existing deck is removed, the upper flange surface of the bridge girder on which the existing deck rests may still have attached debris, such as pieces of concrete that were removed when the existing deck was removed. Furthermore, the existing paint film may peel off from the upper flange surface, leaving the bridge girder surface exposed for a long period of time, causing rust to form.

For this reason, the typical method for replacing concrete decks is to remove the existing deck, then remove any adhesions, rust, and existing paint from the upper flange surface, perform a surface preparation to level the upper flange surface, and then paint the prepared upper flange surface anew before installing the new deck. The type of surface preparation method for the upper flange surface and the type of surface cleaning that specifies the level of surface finish are Type 1 or Type 2 cleaning, as it is necessary to ensure that no impurities remain between the new deck and the upper flange and that the new deck is firmly fixed.

Conventionally, surface preparation methods for the upper flange surface have mainly been based on a type 2 scraping method, in which remaining concrete fragments, rust, and existing paint films are manually removed from the upper flange surface using power tools such as disc sanders and grinders, or hand tools (see, for example, Patent Document 1). Furthermore, remaining concrete fragments, rust, and existing paint films removed from the upper flange surface during surface preparation and scattered around the surface preparation area are manually collected using a broom or similar tool, similar to the removal work described above.

Another surface preparation method uses a vacuum blasting device, which sprays fine abrasives such as sand onto the upper flange surface to remove remaining concrete fragments, rust, and existing paint, and then uses a vacuum to suck up and collect the material removed from the upper flange surface. Non-Patent Document 1 proposes a vacuum blasting device that can be manually moved over bridge girders and is equipped with an automatically swinging blasting device and a vacuum to automatically collect the abrasives sprayed by the blasting device and the removed cleaning chips. The surface preparation method using the vacuum blasting device described above is classified as Type 1 cleaning.

Japanese Patent Application Laid-Open No. 2020-176420

Obayashi Corporation, Flange Blaster TM, September 20, 2019, [Retrieved September 3, 2021], Internet <URL https://www.obayashi.co.jp/solution_technology/detail/tech_d222.html>

However, existing bridge girder coatings may contain hazardous substances such as lead, chromium, and PCBs. In such cases, there are concerns about exposure to the existing coating through the use of power and hand tools during the surface preparation work, and the resulting impact on worker health. In relation to these concerns, the Industrial Safety and Health Act also stipulates that safety and health measures be implemented for workers in painting operations. Furthermore, the use of power and hand tools and the spraying of abrasives during surface preparation work can generate dust that may spread to the surrounding area, raising concerns about the impact on worker health and the safety of the work environment. Therefore, there is a need for a surface preparation method that protects worker health from the hazardous substances contained in the existing coating, protects worker health from dust that may be generated at the work site, and ensures a safe working environment.

Conventional manual surface preparation methods require the manual collection of remaining concrete fragments, rust, existing paint, and other materials scattered around the surface preparation area after completion of the surface preparation. Furthermore, conventional manual surface preparation methods generate loud noises when scraping the upper flange surface with power tools, so the number of hours that can be worked per day is limited due to concerns about noise pollution for neighbors. These issues result in longer construction times for deck replacement work.

In addition, traditional manual surface preparation methods require each worker to perform the work by hand, which poses the issue of potential variations in the quality of the surface preparation due to differences in the skills of each worker.

The surface preparation method using a vacuum blasting device has the problem that abrasive material sprayed onto the upper flange surface can bounce back, or material removed from the upper flange surface can scatter around, requiring additional time and effort to collect this debris.

Furthermore, when using a vacuum blasting machine to condition the surface, depending on the state of deterioration of the upper flange, spraying abrasive material onto the corners of the upper flange surface may cause the sprayed area to break due to the force of the spray. This creates a work load, such as having to adjust the amount of spray depending on the sprayed area, which can also increase work time.

The above issues pose a risk to the health and safety of workers performing surface preparation work during deck replacement work, as well as a potential reduction in the efficiency of surface preparation work and a decline in the quality of the surface preparation surface.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a pulsed laser irradiation device that can ensure a safe working environment and a highly efficient and high-quality surface preparation.

To achieve the above objective, the pulsed laser irradiation device of the present invention comprises a pulsed laser irradiation unit that irradiates a target object attached to a structure with a pulsed laser, a scraper that is inserted between the target object that has been peeled off from the structure by irradiation with the pulsed laser and the structure, and a recovery unit that recovers the target object that has been removed from the structure.

With the above configuration, the pulsed laser irradiation unit irradiates a pulsed laser, breaking down the target material that absorbs the laser light into fine fumes and removing them from the structure. Even target material that adheres to the structure and does not decompose into fumes can be easily removed by irradiating it with the pulsed laser and scraping it off with the vibration of a scraper. The removed target material can be collected by the collection unit without scattering into the surrounding area. Furthermore, because the laser irradiation is a surface preparation process that does not involve projectiles, cleaning up scattered material after the surface preparation process can be omitted, improving the efficiency of the surface preparation process. Furthermore, because the target material is collected without scattering into the surrounding area, a safe working environment can be ensured and the desired surface preparation can be performed, even if the target material contains hazardous substances. Furthermore, surface preparation can be performed simply by irradiating the target material with a pulsed laser and scraping off the peeled material with the vibration of a scraper, eliminating quality differences between workers involved in manual surface preparation processes and resulting in a uniform, high-quality surface.

In addition, in the pulsed laser irradiation device according to the present invention, the pulsed laser irradiation unit may include an air injection unit that injects air onto the bottom of the peeled object to be removed, forming a gap below the object to be removed into which the scraper can be inserted.

The above configuration allows the scraper to be easily inserted beneath the removed material. Therefore, even if the material has been decomposed into fumes and there is concrete fragments or other material attached to it that has not yet decomposed into fumes, it can be easily removed from the structure. Furthermore, by scraping off the material directly, it is possible to reduce the amount of material that is left unremoved or recovered, improving the quality of the finished surface.

Furthermore, in the pulsed laser irradiation device according to the present invention, the pulsed laser irradiation unit may be equipped with a vibration unit that vibrates the scraper.

With the above configuration, the scraper can be easily inserted underneath to remove material adhering to a structure, facilitating removal. Furthermore, even if the surface to be adjusted is rough, such as uneven, the scraper can be inserted underneath the material to be adjusted without the pulsed laser irradiation device getting caught on the surface, allowing for the desired surface adjustment to be carried out. Therefore, a high-quality finished surface can be achieved regardless of the shape of the surface to be adjusted.

Furthermore, in the pulsed laser irradiation device according to the present invention, the irradiation angle of the pulsed laser may be between 5° and 15° relative to the vertical.

The above configuration can prevent breakdowns of the various components of the pulsed laser irradiation device caused by the reflected pulsed laser when a pulsed laser is irradiated onto a structure having a substrate surface with a high reflectivity of laser light. Furthermore, because the pulsed laser is irradiated onto the object to be removed at an angle close to a right angle, the energy of the irradiation acting on the focal point (object to be removed) where the laser light is irradiated can be increased. This makes it possible to effectively achieve the desired peeling effect. Furthermore, because it is easier to irradiate the pulsed laser onto the bottom of the object to be removed, which makes it easier to create gaps due to peeling, it is easier to insert a scraper underneath the object to be removed.

Furthermore, in the pulsed laser irradiation device according to the present invention, the recovery unit may be equipped with a classification mechanism that classifies the recovered removal target material according to particle size.

With the above configuration, when the materials to be removed collected by the collection unit include large particles that do not decompose into fumes, such as concrete debris, the collected fume-like materials can be easily separated from other materials. This makes disposal of the materials to be removed easier and more efficient.

In addition, in the pulsed laser irradiation device according to the present invention, the structure may be the upper flange of a bridge girder, the surface of which is exposed by removing the bridge deck and is painted with an existing paint film.

As a result of the above, it is possible to improve the efficiency of surface preparation work and shorten construction times in bridge deck replacement work, which requires shorter construction times due to shorter traffic restriction periods.

Furthermore, in the pulsed laser irradiation device according to the present invention, the object to be removed may include concrete pieces that adhere when the deck slab is removed, rust that occurs on the upper flange, and the existing paint film.

As a result of the above, concrete pieces adhering to the upper flange, sandwiching the existing coating, can be peeled off from the upper flange by irradiating the existing coating with a pulsed laser. The peeled concrete pieces can then be easily removed from the upper flange by scraping them off with the vibration of a scraper, completing the surface preparation.

According to the present invention, it is possible to provide a pulsed laser irradiation device that can ensure a safe working environment and a highly efficient and high-quality surface preparation.

1 is an explanatory diagram showing an example of the overall configuration of a pulsed laser irradiation device according to an embodiment of the present invention. 1 is a partial perspective view showing an example of a pulsed laser irradiation device according to an embodiment of the present invention. 2 is a partial cross-sectional view taken along the line AA in FIG. 1 ;

The pulsed laser irradiation device 1 according to an embodiment of the present invention will be described below with reference to Figures 1 to 3.

As shown in Figures 1 to 3, the pulsed laser irradiation device 1 has a pulsed laser irradiation unit 11, a storage unit 12, a scraper 13, an air injection unit 14, a vibration unit 15, a recovery unit 16, and a power supply unit 17. The pulsed laser irradiation device 1 removes a removal target 25 from the surface 21 of a structure 2, including an existing paint film 22, deposits 23, rust 24, etc. The power supply unit 17 is a known generator that can be installed at the construction site. The surface 21 has a high reflectivity for the pulsed laser 11a, and the removal target 25 includes material that absorbs the irradiated pulsed laser 11a.

The pulsed laser irradiation unit 11 has a scanner head 111, a transmission tube 112, and a laser oscillation unit 113. The laser oscillation unit 113 is electrically connected to the power supply unit 17.

The scanner head 111 has an upper end connected to one end of the transmission tube 112 and a lower end connected to the upper end of the storage section 12. The scanner head 111 is equipped with a lens 111a and a dustproof section 111b. The lens 111a is provided at the lower end of the scanner head 111, and the dustproof section 111b is provided above the lens 111a. The lens 111a has a specific focal length. The lens 111a is selected depending on the distance to the irradiation target, the shape of the irradiation target, etc. When the focal length of the lens 111a and the distance from the lens 111a to the irradiation target match, the heating effect by irradiating the laser light is maximized.

The transmission tube 112 is connected to the upper end of the scanner head 111 and the laser oscillation unit 113, and transmits the pulsed laser 11a emitted from the laser oscillation unit 113. The transmission tube 112 is, for example, a known fiber cable for laser transmission.

The laser oscillation unit 113 oscillates the laser light 11a in a pulsed manner. Hereinafter, the laser light 11a oscillated by the pulse laser irradiation unit 11 will be referred to as the pulse laser 11a. The laser oscillation unit 113 is equipped with a control unit 113a that adjusts the start and end of irradiation and the irradiation intensity of the pulse laser 11a, making it easy to adjust the irradiation of the pulse laser 11a.

The storage unit 12 comprises a cylindrical portion 121, a handle portion 122, and legs 123. The cylindrical portion 121 has a cylindrical shape that is circular in plan view, with its upper end connected to the lower end of the scanner head 111 and its upper end closed except for the connection point with the scanner head 111. The storage unit 12 is made of a material that has high reflectivity for the pulsed laser 11a and is highly resistant to temperature increases due to laser irradiation. For example, a known steel material with high laser reflectivity can be used.

The handle portion 122 protrudes outward from the outer periphery 124 of the cylindrical portion 121 and has a generally U-shape when viewed from the front. A pair of legs 123 are provided at opposing positions on the outer periphery 124. Each leg 123 comprises a first connection portion 123a connected to the outer periphery 124 and protruding downward from the lower end of the cylindrical portion 121 by several millimeters to several centimeters, and a grounding portion 123b extending from the lower end of the first connection portion 123a to the outside of the cylindrical portion 121. The first connection portion 123a and the grounding portion 123b are formed as a single unit. The grounding portion 123b is grounded to the surface 21, stably positioning the storage portion 12. The pair of legs 123, 123 are connected to the outer periphery 124 at two locations approximately 90° from the installation position of the handle portion 122 when viewed from above. The first connecting portion 123a protrudes from the lower end of the cylindrical portion 121, forming a small opening 125 at the bottom. The pulsed laser irradiation device 1 includes portions made of known steel materials, and is heavy, so it can be used by placing it on the surface 21 and placing it on the surface 21.

The scraper 13 has a second connection portion 131 connected to the outer periphery 124, and a scraped-off portion 132 extending from the lower end of the second connection portion 131 toward the interior of the storage section 12. The second connection portion 131 and the scraped-off portion 132 are formed as a single unit. The upper surface 132a of the scraped-off portion 132 slopes downward toward the tip 132b. The tip 132b forms the tip of the triangular shape of the scraped-off portion 132 in a side view. The second connection portion 131 is located opposite the handle portion 122 in a plan view of the outer periphery 124. The second connection portion 131 is connected to the outer periphery 124 at a position opposite the handle portion 122 and protrudes slightly from the lower end of the cylindrical portion 121. The scraped-off portion 132 extends toward the interior of the storage section 12 through the opening 125.

The air injection unit 14 comprises a pair of moving pipes 141, 141 and an air pressure delivery unit 142. The moving pipe 141 is connected to the outer periphery 124 and the air pressure delivery unit 142, and is engaged with the suction head 165 of the recovery hose unit 161 (described below). The pair of moving pipes 141, 141 are connected to the cylindrical portion 121 on the left and right of the second connection unit 131, and are positioned so that their tips are adjacent to the scraping-off portion 132 inside the cylindrical portion 121. Air compressed by the air pressure delivery unit 142 moves through the moving pipe 141. The air pressure delivery unit 142 is connected to the power supply unit 114 and connected to the moving pipe 141. This is a known air compressor. The air pressure delivery unit 142 is, for example, a known air compressor.

The vibration unit 15 is connected to the second connection part 131. The vibration unit 15 has a power source 151 and vibrates the scraper 13. The vibration unit 15 is, for example, a known vibrator, and the power source 151 is, for example, a known compressor and battery.

The recovery unit 16 includes a recovery hose portion 161, a classification mechanism 162, and a dust collector 163. One end of the recovery hose portion 161 is connected to the outer periphery 124, and the other end is connected to the dust collector 163. The recovery unit 16 sucks in and collects the objects to be removed 25 removed from the surface 21. The classification mechanism 162 classifies and collects the collected objects to be removed 25 according to particle size. The classification mechanism 162 is provided in the middle of the recovery hose portion 161. The classification mechanism 162 includes a gravel removal unit 162a and a small piece sorting unit 162b. The dust collector 163 collects fine dust and other particles from the objects to be removed 25 that have passed through the classification mechanism 162. The dust collector 163 is electrically connected to the power supply unit 17.

The recovery hose section 161 comprises a hose 164 and a suction head 165. One end of the hose 164 is connected to the dust collector 163, and the other end is connected to the suction head 165. One end of the suction head 165 is connected to the outer periphery 124, and the other end is connected to the hose 164.

The suction head 165 comprises a third connection portion 165a, a branch portion 165b, and a pair of dust collection portions 165c, 165c. One end of the third connection portion 165a is connected to the hose 164, and the other end is connected to the branch portion 165b. The branch portion 165b has one end connected to the third connection portion 165a and the other end connected to each of the pair of dust collection portions 165c, 165c, thereby branching the recovery hose portion 161. Each of the pair of dust collection portions 165c, 165c is connected to the branch portion 165b at one end and to the outer periphery portion 124 at the other end. The pair of dust collection portions 165c, 165c, like the pair of legs 123, 123, are connected to two locations on the outer periphery portion 124 at approximately 90° from the installation position of the handle portion 122 in a plan view. The connection portions between the pair of dust collection sections 165c, 165c and the outer periphery 124 are located close to both ends of the scraping section 132 in a direction perpendicular to the extension direction in plan view. As described above, the recovery unit 16 can use the pair of dust collection sections 165c, 165c to suck and recover the objects to be removed 25 from both ends of the scraping section 132 in one direction. This prevents the objects to be removed 25 from being missed during the surface adjustment work.

The dust collection unit 165c has a bracket portion 165d at its upper portion that engages the moving pipe 141. The pair of bracket portions 165d, 165d each protrude toward the surrounding portion 165e, which is surrounded by the cylindrical portion 121, the branch portion 165b, and the pair of dust collection units 165c, 165c in a plan view, and engages the pair of moving pipes 141, 141 within the surrounding portion 165e. The pair of moving pipes 141, 141 are connected to the outer periphery 124 within the surrounding portion 165e. The pair of moving pipes 141, 141 are arranged so that their positioning within the cylindrical portion 121 does not shift by being engaged with the bracket portions 165d, 165d, respectively.

Multiple gravel removal units 162a are provided between the suction head 165 and the small piece sorting unit 162b. The multiple gravel removal units 162a classify and collect large particle sizes of the objects to be removed 25 sucked and collected from the suction head 165 multiple times. The objects to be removed 25 that have passed through the multiple gravel removal units 162a are sent to the small piece sorting unit 162b. The gravel removal unit 162a is, for example, a trap that separates and classifies objects passing through the collection hose section 161 based on their weight.

The small piece sorting unit 162b separates the objects to be removed 25 that have passed through the gravel removal unit 162a into dust particles within the objects to be removed 25 and small pieces within the objects to be removed 25 that have passed through the gravel removal unit 162a, and collects the small pieces. The objects to be removed 25 that have passed through the small piece sorting unit 162b are sent to the dust collector 163 and collected.

A method for removing an object to be removed 25 using a pulsed laser irradiation device 1 in this embodiment will be described below. Hereinafter, the structure 2 to which the pulsed laser irradiation device 1 is applied will be described as the upper flange of a bridge girder (H-shaped steel) on a road bridge where deck replacement work is being carried out. The bridge girder extends along the direction of travel of the road bridge. In this case, the surface 21 corresponds to the upper surface of the upper flange, and the attachment 23 corresponds to the remaining concrete pieces remaining after the existing deck has been removed (hereinafter, "surface 21" will be referred to as "upper surface 21" and "attachment 23" will be referred to as "remaining concrete pieces 23").

The object to be removed 25 remaining at the edge of the upper surface 21 is the object to be removed by the pulsed laser irradiation device 1. The edge of the upper surface 21 is an area where the removed object to be removed 25 may scatter into the surrounding area if a conventional surface preparation method, such as a blasting device, is applied. The object to be removed 25 has remaining concrete pieces 23 located above the existing paint film 22 and rusted area 24. The surface preparation using the pulsed laser irradiation device 1 in this embodiment is a type 1 cleaning process.

The scraper 13, air injection unit 14, vibration unit 15, and recovery unit 16 are each connected to the outer periphery 124 of the storage section 12, and the scanner head 111 is connected to the upper end of the storage section 12, thereby providing the pulsed laser irradiation device 1 as an integrated device.

During surface preparation, the storage unit 12 is tilted at an irradiation angle α relative to the upper surface 21. The irradiation angle α is in the range of 5° to 15°. In this embodiment, the irradiation angle α is set to 5° by tilting the storage unit 12 5° from the vertical. The pulsed laser irradiation device 1 directly irradiates the target object 25 on the upper surface 21 with the pulsed laser 11a generated by the laser oscillation unit 113, passing through the transmission tube 112, and emitted from the scanner head 111 at an inclined irradiation angle α. Furthermore, since the upper surface 21 is made of steel, it has a high reflectivity for laser light. Therefore, a portion of the reflected pulsed laser 11a further irradiates the heated target object 25, easily heating the target object 25. The above mechanism promotes absorption of the pulsed laser 11a by portions of the target object 25 that absorb laser light. Because the storage unit 12 is located above the target object 25, the pulsed laser 11a is irradiated, preventing the emitted or reflected pulsed laser 11a from leaking to the outside, allowing for safe operation. By continuing to irradiate the object to be removed 25 with the pulsed laser 11a, the irradiated object to be removed 25 begins to peel off from the upper surface 21.

The mechanism for removing the existing coating film 22 and rusted portions 24 from the upper surface 21 of the object to be removed 25 at locations where the remaining concrete pieces 23 are not attached will be described below.
The removal target 25, which has begun to peel off due to the continuous irradiation of the pulsed laser 11a, continues to be heated by further continuous irradiation of the pulsed laser 11a. Thereafter, due to the difference in thermal expansion between the removal target 25 and the upper surface 21, wrinkles form at the adhesive surface between them, and the removal target 25 peels off from the upper surface 21. Furthermore, the removal target 25 peeled off as described above further absorbs the light reflected from the upper surface 21. As a result, thermal energy is continuously applied to the removal target 25 that has absorbed the laser light, and laser ablation causes it to sublimate, generating instantaneously evaporated plasma and particles (hereinafter referred to as "fumes 26") that are finer than dust, and the removal target 25 is peeled off and removed from the upper surface 21.

The mechanism for removing the existing coating 22 and rusted portions 24 from the upper surface 21 of the object 25 to be removed, where the remaining concrete pieces 23 are attached, will be described below.
The pulsed laser irradiation device 1 irradiates the pulsed laser 11a at the lower part of the remaining concrete fragments 23 of the removal target 25 at an irradiation angle α, thereby removing the existing coating film 22 underneath the remaining concrete fragments 23 and partially peeling off the remaining concrete fragments 23. With the remaining concrete fragments 23 in a partially peeled state, the air injection unit 14 forms a gap below the remaining concrete fragments 23 (between the upper surface 21 and the remaining concrete fragments 23) into which the scraping part 132 can be inserted. The vibration unit 15 then vibrates the scraping part 132 while the storage unit 12 is moved horizontally, inserting the scraping part 132 below the remaining concrete fragments 23. The inserted scraping part 132 is further moved horizontally while being vibrated by the vibration unit 15, thereby crushing and peeling off the remaining concrete fragments 23 and removing them from the upper surface 21. Based on the above mechanism, the remaining concrete fragments 23 are peeled off from the upper surface 21 by applying additional force in addition to the irradiation of the pulsed laser 11a. When the existing coating 242 and rusted portion 244 underneath the remaining concrete pieces 23 are removed by irradiation with the pulsed laser 11a, the remaining concrete pieces 23 are removed and collected in the form of concrete shells without being decomposed into fumes.

The area of the upper surface 132a is smaller than the planar area of the cylindrical portion 121 and is formed taking into account the remaining area of the remaining concrete pieces 23, etc. The tip 132b is formed in a shape that will not cause damage to the upper surface 21 due to horizontal movement of the storage portion 12.

The heating effect of the pulsed laser 11a is greatest when the focal length of the lens 111a matches the distance from the lens 111a to the object 25 to be removed, onto which the laser light is irradiated, and is small when they do not. Therefore, at distances where the laser light is out of focus, work can be carried out safely even if, for example, a worker's hand is irradiated.

The dustproof section 111b closes the scanner head 111 from the storage section 12, preventing the removed object 25 from entering the transmission tube 112.

The fumes 26 and the detached remaining concrete fragments 23 are sucked through the suction head 165 and collected in the collection unit 16. The collected fumes 26 and remaining concrete fragments 23 pass through the collection hose section 161 and reach the classification mechanism 162. The gravel removal unit 162a captures and collects the remaining concrete fragments 23 by particle size. The fumes 26 that pass through the classification mechanism 162 reach the dust collector 163 and are collected. The collection unit 16 is always in operation during the removal work of the object to be removed 25, and removal of the object to be removed 25 from the top surface 21 and suction and collection by the collection unit 16 are carried out continuously.

The suction head 165 collects the fumes 26 and the remaining concrete fragments 23 by pulling them, and the storage section 12 is always kept under negative pressure when removing the object 25. Therefore, the fumes 26 and remaining concrete fragments 23 removed from the upper surface 21 are collected without being released outside the storage section 12.

Fumes 26 generated by irradiation with the pulsed laser 11a must not be exposed to the environment, regardless of whether they are metallic, chemical, or other types. Therefore, the pulsed laser irradiation device 1 uses the storage unit 12 to surround the area irradiated by the pulsed laser 11a, suppressing the diffusion of the laser light while also preventing exposure to the fumes 26, allowing the fumes 26 to be sucked in and collected without scattering into the surrounding area.

Surface preparation using the pulsed laser irradiation device 1 involves directly irradiating the object 25 with a pulsed laser 11a, removing the object 25, and then suctioning and collecting the fumes 26 and the remaining concrete fragments 23 that have been removed. Therefore, compared to other surface preparation methods that use a blasting mechanism, this method results in fewer objects being scattered during the surface preparation process.

The pulsed laser irradiation device 1 is positioned so that the handle 122 faces the direction of progress of the surface preparation, and performs surface preparation along the direction of travel of the road bridge (the direction in which the upper flange extends). Furthermore, when performing surface preparation work, the worker 3 holds the cylindrical portion 121 and handle 122 while moving the storage unit 12 horizontally in the direction of travel of the road bridge.

Next, the operation and effects of the pulsed laser irradiation device 1 according to the embodiment of the present invention described above will be explained using the drawings.

The pulsed laser irradiation device 1 according to this embodiment decomposes the target object 25, which absorbs laser light, into fumes 26, partially peels off the remaining concrete fragments 23, which have a high reflectivity to laser light, from the upper surface 21, creating a gap below into which the scraper 13 can be inserted. The scraper 13 then vibrates to scrape off and remove the fragments, which are then collected in the collection unit 16 almost simultaneously with the removal. As a result, surface preparation work, including the desired surface treatment and cleaning of the upper surface 21, can be carried out without scattering or generating substances that affect the work environment, such as the target object 25 or dust associated with the surface preparation work. In addition, because no tangible substance, such as blasting material, is required to be projected onto the upper surface 21, cleaning up scattered debris after the surface preparation work can be omitted, improving the efficiency of the surface preparation work.

The pulsed laser irradiation device 1 can reduce the amount of debris generated during surface preparation work, ensuring a safe working environment for the worker 3 even if the existing coating film 22 contains harmful substances.

The pulsed laser irradiation device 1 irradiates the object to be removed 25 with a pulsed laser 11a, and any peeled material is scraped off by horizontally moving the storage unit 12 and vibrating the scraper 13, allowing for surface preparation through a simple process. This eliminates quality differences between workers on the surface preparation, resulting in a uniform, high-quality surface.

In addition, by injecting air from the air injection unit 14 between the upper surface 21 and the remaining concrete pieces 23, a gap is formed below the remaining concrete pieces 23 into which the scraping part 132 can be inserted. As a result, the scraper 13 can be easily inserted below the remaining concrete pieces 23. Even the remaining concrete pieces 23, which are deposits that do not decompose into fumes when irradiated with a pulsed laser, can be easily removed from the structure. Furthermore, by directly scraping off the material to be removed, it is possible to reduce the amount of material that is left unrecovered, improving the quality of the finished surface.

In addition, during the surface preparation work, the scraper 13 is moved horizontally while being vibrated by the vibration unit 15. As a result, the scraper 13 can be easily inserted under the remaining concrete pieces 23, further facilitating the removal of the remaining concrete pieces 23. Furthermore, even if the upper surface 21 is an uneven, rough surface, the pulsed laser irradiation device 1 does not get caught on the upper surface 21 when moved horizontally, allowing for smooth surface preparation work. Therefore, the quality of the finished surface can be improved regardless of the shape of the upper surface 21.

The pulsed laser irradiation device 1 also irradiates the pulsed laser 11a at an inclined irradiation angle α from the top surface 21. This prevents equipment failures, such as the scanner head 111, caused by the pulsed laser 11a being reflected from the top surface 21, which is a steel surface with high laser reflectivity. Furthermore, by irradiating the pulsed laser 11a from a position inclined at an irradiation angle α, the energy of the irradiation acting on the object 25 to be removed when irradiated with the pulsed laser 11a can be increased. This effectively prevents equipment failures, such as those of the pulsed laser irradiation device 1, while achieving the desired removal effect. Furthermore, the configuration of irradiating the pulsed laser 11a at an irradiation angle α makes it easier to irradiate the adhesion areas at the bottom of the remaining concrete fragments 23. This makes it easier to remove the remaining concrete fragments 23, which have a high laser reflectivity and are less likely to absorb laser light, and create gaps at the bottom. This allows the scraper 13 to be easily inserted below the remaining concrete fragments 23.

In addition, the remaining concrete pieces 23 collected in the collection unit 16 are classified and collected multiple times in the gravel removal unit 162a of the classification mechanism 162, with larger particle sizes. Smaller particle sizes that pass through the gravel removal unit 162a are collected by the small particle sorting unit 162b. Fine particles such as dust that are not collected by the small particle sorting unit 162b are collected in the dust collector 163 together with the fumes 26. This makes it easy to separate and process the remaining concrete pieces 23 and the fumes 26. It also makes disposal more efficient when the existing paint film contains harmful substances.

Although the embodiment of the pulsed laser irradiation device according to the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate within the scope of the invention.
For example, in the above embodiment, the pulsed laser irradiation device 1 is equipped with an air injection unit 14, but it may be configured without the air injection unit 14 if the scraper 13 can be easily inserted under the remaining concrete pieces 23.

In the above embodiment, the pulsed laser irradiation device 1 is equipped with a vibration unit 15, but if the scraper 13 can be easily inserted under the remaining concrete pieces 23 and the remaining concrete pieces 23 can be easily removed, the device may be configured without the vibration unit 15.

In the above embodiment, the pulsed laser irradiation device 1 irradiates the pulsed laser 11a at an angle of irradiation α, but it may also be configured so that the irradiation angle is not tilted unless the reflected pulsed laser 11a is irradiated onto equipment such as the scanner head 111.

In the above embodiment, the pulsed laser irradiation device 1 is equipped with a classification mechanism 162, but if classification is not required, the device may be configured without the classification mechanism 162.

For example, in the above embodiment, the pulsed laser irradiation device 1 performs the surface preparation work by moving the storage unit 12 horizontally, but the lower end of the cylindrical portion 121 may be provided with a movement mechanism that allows the storage unit 12 to move freely while surrounding the irradiation area. Examples of the movement mechanism include well-known casters for movement.

In the above embodiment, the target of irradiation with the pulsed laser is the upper surface of the upper flange of a bridge girder during deck replacement work, but the pulsed laser irradiation device 1 may also be applied to surface preparation work in other construction projects. For example, this can be used to prepare the surface of a base material that absorbs laser light, such as removing existing paint from a painted wooden structure.

1. Pulse laser irradiation device 2. Structure (upper flange of bridge girder)
11 Pulse laser irradiation unit 11a Pulse laser (laser light)
13 Scraper 14 Air injection unit 15 Vibration unit 16 Recovery unit 22 Existing coating film 23 Remaining concrete pieces (concrete pieces)
24 Rust part 25 Object to be removed 162 Classification mechanism α Irradiation angle

Claims (6)

a pulse laser irradiation unit that irradiates a target object attached to the structure with a pulse laser;
a scraper inserted between the structure and the object to be removed that has been peeled off from the structure by irradiation with the pulsed laser;
a recovery unit that recovers the removal target removed from the structure;
Equipped with
The recovery unit includes a recovery hose portion and a classification mechanism that classifies the recovered objects to be removed according to particle size,
The recovery hose portion includes a hose and a suction head.
The classification mechanism includes a gravel removal unit and a small piece sorting unit,
The gravel removal unit is provided in plurality between the suction head and the small piece sorting unit,
The small piece sorting unit is a pulsed laser irradiation device that classifies the objects to be removed that have passed through the multiple gravel removal units into dust and small pieces and recovers the small pieces . The pulsed laser irradiation unit includes an air injection unit that injects air onto a lower portion of the peeled removal object to form a gap into which the scraper is inserted at the lower portion of the removal object.
The pulsed laser irradiation device according to claim 1 . The pulsed laser irradiation unit includes a vibration unit that vibrates the scraper.
The pulsed laser irradiation device according to claim 1 or 2. The irradiation angle of the pulsed laser is 5° or more and 15° or less with respect to the vertical.
The pulsed laser irradiation device according to any one of claims 1 to 3. The structure is an upper flange of a bridge girder whose surface, exposed by removing the bridge deck, is painted with an existing paint film.
The pulsed laser irradiation device according to any one of claims 1 to 4 . The objects to be removed include concrete pieces that adhere when the deck is removed, rust that occurs on the upper flange, and the existing paint film.
The pulsed laser irradiation device according to claim 5 .