JP7852866B2 - Unmanned aerial vehicle (UAV) for spray coating resin materials - Google Patents

Description

This invention relates to an apparatus for spray-coating the surface of structures with resins, polymer cements, etc., using an unmanned aerial vehicle.

The surfaces of wind turbine blades, towers, and other structures inevitably deteriorate over time due to continuous exposure to wind and rain, and are damaged by collisions with birds and lightning strikes. Similarly, elevated bridge girders, piers, and various other concrete structures also experience cracking, delamination, spalling, and rebar corrosion due to carbonation, salt damage, freeze-thaw damage, fatigue, and weathering. Therefore, regular inspections of structural surfaces are conducted. If inspections reveal peeling of the protective coating or rust on metal parts, the peeled or rusted areas are removed, followed by the application of resin, injection into cracks, and further repairs to form a protective coating on the surface.

Repair work using resin coatings is typically performed by workers, making it particularly dangerous and inefficient at high altitudes. Furthermore, the work period, including preparatory work such as scaffolding assembly or the installation of suspension gondolas, was long and costly.

Therefore, for example, Patent Document 1 proposes a device in which a support body equipped with a discharge unit is suspended by a suspension unit (unmanned aerial vehicle), and a coating agent sent from the ground via a hose is sprayed onto the wall surface of a structure from the discharge unit.

Japanese Patent Publication No. 2023-83932

In the technology proposed in Patent Document 1, the paint is delivered from the ground via a hose, thus limiting the working range to the length of the hose. Furthermore, when using a paint with a melting point above room temperature, the hose needs to be heated and maintained to prevent the paint from solidifying, making it practically difficult to extend the hose length.

Therefore, the object of the present invention is to provide an apparatus that can safely and reliably perform spray coating of polyurethane resin or polyurea resin, which uses raw materials with a melting point above room temperature, onto the surface of structures, within a short preparation period and over a wide work area.

One embodiment of the spray coating apparatus for structural surfaces according to the present invention, which achieves the above objective, is an apparatus for spray coating a polyurethane resin or polyurea resin onto a structural surface using an unmanned aerial vehicle, characterized by comprising: an unmanned aerial vehicle; two or more replaceable containers mounted on the unmanned aerial vehicle, each storing a first liquid consisting of a polyisocyanate compound and a second liquid consisting of a polyol compound or polyamine compound; a heat-insulating member for keeping the containers warm; an actuator for supplying the first and second liquids stored in the containers to a mixer; and a nozzle for spraying the mixed liquid from the mixer onto the structural surface.

In the spray painting apparatus with the above configuration, it is preferable that the actuator comprises an accumulator filled with compressed gas, a cylinder to which compressed gas is supplied from the accumulator, and a piston slidably mounted axially within the cylinder. When compressed gas is supplied to the cylinder, the piston slides axially within the cylinder, causing the piston rod to protrude outward from the cylinder and push out and supply the first and second liquids in the container to the mixer.

Furthermore, in the spray painting apparatus with the above configuration, it is preferable that a camera is further mounted on the unmanned aerial vehicle.

Furthermore, in the spray painting apparatus with the above configuration, it is preferable that the mixer is a static mixer.

According to the spray coating apparatus of the present invention, spray coating of polyurethane resin or polyurea resin, which uses raw materials with a melting point above room temperature, onto the surface of structures can be performed safely and reliably with a short preparation period and over a wide work area.

This is a side view showing one embodiment of a spray painting apparatus according to the present invention. Figure 1 is a top view of the spray painting apparatus. Figure 1 is a schematic diagram of the actuator, container, static mixer, nozzle, and cover of the spray painting apparatus. This is an example block diagram of a spray painting apparatus according to the present invention. This flowchart shows an example of control for a spray painting apparatus according to the present invention.

The following describes in more detail, with reference to the figures, examples of embodiments relating to the spray coating apparatus of the present invention. However, the present invention is not limited in any way to these embodiments.

Figures 1 and 2 show a side view and a top view illustrating one embodiment of a spray painting apparatus according to the present invention. The spray painting apparatus D shown in these figures comprises an unmanned aerial vehicle 1, two containers 2a and 2b (shown in Figure 3) covered with a heat-insulating member 3 mounted on the unmanned aerial vehicle 1, a static mixer (mixer) 4 for mixing a first liquid _L1 and a second liquid _L2 (shown in Figure 3) stored in the containers 2a and 2b respectively, an air-operated actuator 5 for pushing and supplying the first liquid _L1 and the second liquid _L2 from the containers 2a and 2b to the static mixer 4, a nozzle 6 attached to the end of the static mixer 4, and a cover member 7 attached to the nozzle 6. The individual components of the spray painting apparatus D will be described below.

(Unmanned aerial vehicle)
One of the major features of this invention is the use of an unmanned aerial vehicle (UAV) 1 as a means of transport for spray painting repair areas of structures. This eliminates the need for preparatory work such as assembling scaffolding or setting up suspended gondolas, and significantly reduces working time compared to conventional methods. There are no particular limitations on the UAV 1 that can be used in this invention as long as it can carry the containers 2a and 2b (shown in Figure 3) and actuator 5 described later, and commercially available models can be used. The unmanned aerial vehicle 1 shown in Figure 1 comprises a main body 10, four rod-shaped support parts 12a to 12d extending outward from the outer circumference of the main body 10 at approximately equal angular intervals in a plan view, four rotary motors 13a to 13d (hereinafter sometimes collectively referred to as "rotary motors 13") provided at the tip of each of the four support parts 12a to 12d with their rotation axes oriented vertically, four rotor blades 14a to 14d (hereinafter sometimes collectively referred to as "rotary blades 14") attached to the rotation axes of each of the four rotary motors 13, a control unit 15 (shown in Figure 4) for controlling the rotation of the four rotary motors 13, a communication unit 16 (shown in Figure 4), and a power supply 17 (shown in Figure 4). The main body 10 houses the control unit 15, the communication unit 16, and the power supply 17. Furthermore, although the unmanned aerial vehicle 1 is a so-called quadcopter in this embodiment, it is not limited to this, and may be a helicopter or another multicopter with one, three, six, or eight rotors 14. If the battery cannot sufficiently supply the power required for the rotors of the unmanned aerial vehicle, the unmanned aerial vehicle can be suspended from a power cable and receive power from the ground. If the rotor power is obtained from an engine, the unmanned aerial vehicle may be equipped with a generator and receive power from the generator.

The rotation of the rotor blades 14 generates lift for the unmanned aerial vehicle 1. The rotation speed of each rotor blade 14 is individually controlled by each rotary motor 13 via a control signal from the control unit 15. This enables the unmanned aerial vehicle 1 to perform forward, backward, left, right, up, down, turning, and hovering maneuvers.

The unmanned aerial vehicle (UAV) 1 flies under remote control by a pilot, with the communication unit 16 receiving instruction signals and the control unit 15 controlling the drive of multiple rotary motors 13. Alternatively, the UAV 1 may determine its current position and fly using signals from GPS (Global Positioning System) and/or from a ground station. Furthermore, to achieve stable flight, the UAV 1 may be equipped with sensors such as acceleration sensors, angular velocity sensors, barometric pressure sensors, altitude sensors, wind direction and speed sensors, and gyroscope sensors (not shown). In addition, to improve the stability and accuracy of position control, it may be equipped with rotor pitch control.

As shown in Figure 1, a camera 8 is rotatably mounted on the lower surface of the main body 10. Four rod-shaped legs 9a to 9d are attached to the main body 10, extending downwards. A base 90 is fixed to the vertical portion of the four legs 9a to 9d. A heat-insulating member 3 containing the containers 2a and 2b (described later) and an actuator 5 are attached to the upper surface of the base 90.

Camera 8's shooting direction is controlled based on commands from the control unit 15, and it captures images of the structure's surface before and/or after spray painting. The spray painting conditions can also be optimized based on the images of the structure's surface before and/or after spray painting captured by camera 8.

(Containers, heat-insulating materials)
As shown in Figure 3, two containers 2a and 2b mounted on the unmanned aerial vehicle 1 are filled with a polyisocyanate compound as the first liquid _L1 in container 2a and a polyol compound or polyamine compound as the second liquid L2 in container _2b . The two containers 2a and 2b are identical cylindrical in shape and are partially joined together when placed side by side, and are handled as a single unit. The axial ends of the two containers 2a and 2b are connected to a common supply port 22. The rear walls 21a and 21b at the axial rear ends of the two containers 2a and 2b are made movable in the axial direction while maintaining liquid-tightness. As will be described later, when the rods 54a and 54b of the actuator 5 protrude, the rear walls 21a and 21b of the containers 2a and 2b move toward the axial end, and the first liquid _L1 and the second liquid _L2 are pushed out from the containers 2a and 2b to the static mixer 4. Containers 2a and 2b are interchangeable, and when the first liquid _L1 and second liquid _L2 in containers 2a and 2b are used up, they are replaced with new ones. Note that the two containers 2a and 2b do not need to be joined together and may be separate.

Containers 2a and 2b, filled with the first liquid _L1 and the second liquid _L2 , are heated by a heater (not shown) on the ground before being mounted on the unmanned aerial vehicle 1. Once they reach a set temperature (e.g., 75°C), they are kept warm and mounted on the unmanned aerial vehicle 1 immediately before flight. Since the internal temperature of containers 2a and 2b is affected by the ambient temperature, the outer periphery of containers 2a and 2b is covered with an insulating member 3. Containers 2a and 2b may be mounted on the unmanned aerial vehicle 1 while covered with the insulating member 3, or the insulating member 3 may be provided at the mounting points for containers 2a and 2b on the unmanned aerial vehicle 1. Considering the working time, heating elements such as heaters H (shown in Figure 4) may be attached around containers 2a and 2b in addition to the insulating member 3.

When a polyol compound is used as the second liquid _L2 , it reacts with the polyisocyanate compound of the first liquid _L1 to form a polyurethane resin, which is then spray-painted onto the surface of the structure. When a polyamine compound is used as the second liquid _L2 , it reacts with the polyisocyanate compound of the first liquid _L1 to form a polyurea resin, which is then spray-painted onto the surface of the structure.

Polyisocyanate compounds are those having two or more isocyanate groups in a single molecule. Examples of low molecular weight isocyanate compounds that can be used include diphenylmethane-4,4'-diisocyanate (MDI), carbodiimide-modified diphenylmethane diisocyanate (liquid MDI), polymethylene polyphenyl isocyanate (crude MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate, and 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI).

Polyol compounds have two or more alcoholic hydroxyl groups in one molecule; for example, polyether polyols, polyester polyols, and polytetramethylene glycols can be used.

Polyamine compounds are those containing an amino group, and examples include aliphatic polyamines such as triethylenetetramine, aromatic polyamines such as metaphenylenediamine, and alicyclic polyamines such as isophoronediamine.

(Static mixer)
The static mixer 4 has a cylindrical member 41 and an element 42, such as a curved plate, inserted into the cylindrical member 41. As the first liquid _L1 and the second liquid _L2 pass through the static mixer 4, actions such as division and merging, local shearing, stretching and folding occur, and the first liquid _L1 and the second liquid _L2 are mixed. Note that the mixer used in the present invention is not limited to the static mixer 4, and conventionally known mixers can be used, but the use of the static mixer 4 is preferable because of its simple structure and the fact that it does not require power. It is preferable that the static mixer 4 be replaceable, and it is preferable to replace it with a new one after each spray painting operation is completed. That is, it is preferable to replace the static mixer 4 at the same time as replacing the containers 2a and 2b.

(nozzle)
The nozzle 6 sprays the mixed liquid, prepared in the static mixer 4, onto the surface of the structure. Specifically, the nozzle 6 mixes the mixed liquid discharged from the static mixer 4 with air supplied from the accumulator 51 and sprays the mixture. In this embodiment, the spray shape of the mixed liquid is conical, but it is not limited to this and may be a square pyramidal shape, spiral shape, linear shape, etc. The nozzle 6 is detachably attached to the axial end of the static mixer 4. As mentioned above, the static mixer 4 is replaced along with the used containers 2a and 2b, and it is preferable to replace the nozzle 6 in the same manner.

(Actuator)
Figure 3 shows a schematic diagram of the actuator 5. The actuator 5 shown in Figure 3 pushes and supplies the first liquid _L1 and the second liquid _L2 stored in containers 2a and 2b to the static mixer 4. The actuator 5 has an accumulator 51 filled with compressed air, a cylinder 52 to which compressed gas is supplied from the accumulator 51, and a piston 53 that is axially slidable within the cylinder 52. An on-off valve 55, a pressure reducer 56, and a flow control valve 57 are provided between the accumulator 51 and the cylinder 52. A branch pipe is also provided between the pressure reducer 56 and the flow control valve 57, and air at a predetermined pressure is also sent to the nozzle 6.

The pressure of the air filling the accumulator 51 is determined appropriately based on factors such as the spraying time of the mixed liquid sprayed from the nozzle 6, but is usually in the range of 1 MPa to 5 MPa. The pressure after adjustment by the pressure reducer 56 is determined appropriately based on factors such as the spraying speed and spray volume, but is usually in the range of 0.1 MPa to 1 MPa.

When air adjusted to a predetermined pressure by the pressure reducer 56 is supplied from the accumulator 51 to the cylinder 52, the piston 53 slides axially forward within the cylinder 52, causing the rods 54a and 54b of the piston 53 to protrude axially forward from the cylinder 52, moving the rear walls 21a and 21b of the containers 2a and 2b axially forward. As a result, the first liquid _L1 and the second liquid _L2 in the containers 2a and 2b are pushed out and supplied to the static mixer 4.

(Cover component)
The cover member 7 is intended to prevent the mixed liquid ejected from the nozzle 6 from being disturbed by the airflow from the rotor blades 14 of the unmanned aerial vehicle 1. The cover member 7 is detachably attached to the nozzle 6. The shape of the cover member 7 can be appropriately determined according to the ejection shape of the mixed liquid. For example, if the ejection shape of the mixed liquid is conical, as shown in Figures 1 and 2, the shape of the cover member 7 should also be conical. The cover member 7 may be in contact with the surface of a structure. That is, the cover member 7 may be designed to cover the entire flight path from where the mixed liquid is ejected from the nozzle 6 to the surface of a structure. A flexible material is preferred for the cover member 7.

Figure 4 shows a block diagram of a spray painting apparatus D according to one embodiment of the present invention. The spray painting apparatus D includes a communication unit 16 that receives remote instructions from the pilot of the unmanned aerial vehicle 1 and transmits images from the camera 8 to a remote control device (not shown), and a control unit 15 that controls the operation of the rotary motor 13 and the opening and closing of the on-off valve 55 for the supply of compressed air based on the instruction information received from the pilot.

(Spray painting operation)
Figure 5 shows a flowchart illustrating an example of the control of the spray painting apparatus D according to the present invention. The unmanned aerial vehicle 1 flies from a ground base to the repair area of a structure surface that requires spray painting, based on remote instructions from the pilot (step S101). Specifically, the pilot inspects the structure surface for peeling paint, rust on metal parts, cracks or peeling on concrete surfaces, etc., while viewing images transmitted from the camera 8 mounted on the unmanned aerial vehicle 1. Alternatively, if the repair area has been identified and its location information has been entered in a prior inspection, the unmanned aerial vehicle 1 flies to the identified location using a GPS system or the like.

When the unmanned aerial vehicle 1 reaches the repair area on the surface of the structure, the unmanned aerial vehicle 1 performs a hovering operation so that the mixed liquid from the nozzle 6 is sprayed onto the repair area (step S102). Then, the on-off valve 55 is opened and the air supplied from the accumulator 51 is reduced to a predetermined pressure by the pressure reducer 56. The reduced pressure air is then supplied to the cylinder 52 and nozzle 6 of the actuator 5. When air is supplied to the cylinder 52, the piston 53 inside the cylinder 52 moves forward, and the two rods 54a and 54b connected to the piston 53 also move forward. The two rods 54a and 54b then move the rear walls 21a and 21b of the two containers 2a and 2b forward, pushing the first liquid _L1 and the second liquid L2 inside the two containers 2a and _2b into the static mixer 4.

The first liquid _L1 and the second liquid _L2 are mixed as they pass through the static mixer 4 and supplied to the nozzle 6. The mixed liquid is then sprayed outward from the tip of the nozzle 6 along with air supplied from the accumulator 51 (step S103).

While the mixed liquid is being sprayed from the nozzle 6, the unmanned aerial vehicle 1 is controlled automatically or remotely so that the sprayed coating film on the repair area reaches the desired thickness. The thickness of the sprayed coating film on the repair area is calculated from the quotient V/A (mm) between the sprayed coating amount V ( ^mm³ /s) of the mixed liquid and the sprayed area A ( ^mm² /s). The sprayed coating amount V ( ^mm³ /s) of the mixed liquid is determined by the amount of air supplied to the cylinder per unit time. The amount of air supplied to the cylinder per unit time can be adjusted in advance. The sprayed area A ( ^mm² /s) of the mixed liquid is determined by the spray shape from the nozzle (including the spread angle), the distance between the nozzle and the repair area, and the speed of the unmanned aerial vehicle 1. Therefore, the unmanned aerial vehicle 1 is controlled to fly at a predetermined speed at a predetermined distance from the repair area so that the sprayed coating film on the repair area reaches the desired thickness.

Next, it is determined whether the first liquid _L1 or the second liquid _L2 has been consumed (step S104). If it is determined that the first liquid _L1 or the second liquid _L2 has been consumed before the spray painting of the mixed liquid to the repair area is completed ("Y" in step S104), the spray painting operation is temporarily terminated. The unmanned aerial vehicle 1 returns to the ground base and replaces the empty container with a new one. At this time, the static mixer and nozzle are also replaced with new ones. After that, it flies back to the repair area and resumes spray painting (steps S101 to S103).

On the other hand, if it is determined that the first liquid _L1 or the second liquid _L2 has not been consumed ("N" in step S104), then it is determined by the image from the camera whether the spray painting of the repair area has been completed (step S105). If the spray painting of the mixed liquid on the repair area has not been completed ("N" in step S105), the spraying of the mixed liquid continues until the spray painting of the repair area is completed.

In this embodiment, even if the first liquid _L1 and second liquid _L2 remain in the container, the aircraft will return to the ground base after spray painting the replenished section, exchange the container for a new one, and then fly to the next repair section. This is because the first liquid _L1 and second liquid _L2 react and solidify immediately upon mixing, causing the container's supply port, static mixer, and nozzle to become blocked during transit to the next repair section.

Furthermore, without departing from the spirit of the present invention, the components in the embodiments described above can be replaced with well-known components as appropriate, and the various modifications described above can be combined as appropriate.

According to the spray painting apparatus of the present invention, spray painting of structural surfaces can be performed safely and reliably with a short preparation period.

1. Unmanned aerial vehicle 2a, 2b. Container 3. Heat-insulating material 4. Static mixer (mixer)
5 Actuator 6 Nozzle 7 Cover 8 Camera 51 Accumulator 52 Cylinder 53 Piston 54a, 54b Rod D Spray painting apparatus H Heater L ₁ First liquid L ₂ Second liquid

Claims (5)

An apparatus for spray-painting polyurethane resin or polyurea resin onto the surface of a structure using an unmanned aerial vehicle,
Unmanned aerial vehicles and
Two or more replaceable containers, each storing a first liquid consisting of a polyisocyanate compound and a second liquid consisting of a polyol compound or a polyamine compound, are mounted on the aforementioned unmanned aerial vehicle.
A heat-insulating member for keeping the aforementioned container warm,
An actuator supplies the first liquid and the second liquid stored in the container to a mixer,
A nozzle for spraying the mixed liquid, which has been mixed in the aforementioned mixer, onto the surface of the structure,
A spray painting apparatus characterized by being equipped with [a specific feature]. The actuator,
An accumulator filled with compressed gas,
A cylinder supplied with compressed gas from the aforementioned accumulator,
The cylinder has a piston that is slidably mounted in the axial direction,
The spray painting apparatus according to claim 1, wherein compressed gas is supplied to the cylinder, causing the piston to slide axially within the cylinder, and the rod of the piston protrudes outward from the cylinder, pushing out and supplying the first liquid and the second liquid in the container to the mixer. The spray painting apparatus according to claim 1 or 2, wherein the mixer is a static mixer. The spray painting apparatus according to claim 1 or 2, further comprising a camera. The spray coating apparatus according to claim 1 or 2, further comprising a cover member that covers the outer circumference of the mixed liquid sprayed from the nozzle.