A peeling device and peeling method for peeling the surface of an artificial structure.

Abstract

To provide a device and method to detach the surface of a hard artificial structure made of asphalt, concrete, mortar, etc. by applying a plasma arc to the hard artificial structure.SOLUTION: A device that detaches the surface of a hard artificial structure made of asphalt, concrete, mortar, etc. has a plasma generating part, a liquid supply part that supplies an electrolyte to the surface of the artificial structure, and an electrode part made of a conductive material and arranged so as to be in contact with the electrolyte; the detachment device and detachment method bring about electric discharge between the electrolyte applied to the surface of the artificial structure and the plasma generating part, and detach the surface of the artificial structure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a peeling device and a peeling method for peeling a surface portion of an artificial structure.

Background Art

[0002] Traffic marking is performed by applying a thermoplastic coating material containing a pigment of any color, a synthetic resin such as rosin ester, any filler and the like to the surface of an artificial structure such as a road surface of a road and a wall surface of a tunnel. Due to circumstances such as structural changes of existing structures, such as road relocation and changes to parking sections in parking lots, existing traffic markings may be peeled off and new traffic markings applied. In addition, the surface of an artificial structure may be peeled for the purpose of roughening the surface of a portion to be constructed before applying a coating material to improve the adhesion of the coating material.

[0003] Patent Document 1 discloses an apparatus for peeling off existing road markings. In this apparatus, water is injected at high pressure against existing road markings to peel off the existing road markings. It is described that the residue of the peeled road marking is sucked under negative pressure.

[0004] Patent Document 2 also discloses an apparatus for peeling off existing road markings. In this apparatus, it is described that a laser is irradiated onto existing road markings to remove the road markings.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described in Patent Document 1, a method for removing road markings by spraying water at high pressure requires, in addition to the device itself, a vehicle to transport the device to the construction site, a tank for storing a large amount of water and a vehicle carrying the tank, and a tank for storing the water containing the sucked-up residue and a vehicle carrying the tank. Including the vehicles accompanying the device, the entire system is large-scale and requires a large number of personnel for operation.

[0007] As described in Patent Document 2, the method of removing road markings with a laser is time-consuming. A laser focuses light onto a small area using a focusing lens and then irradiates it. To process a large area like road markings, a laser takes too long.

[0008] On the other hand, when using plasma, the characteristics differ from those of a laser, which means it may be possible to process a larger area in a shorter time. However, when applying plasma to an insulator such as asphalt, concrete, or mortar, it is difficult to directly pass current through the insulator, so it is necessary to use a method of blowing a plasma jet onto the object. In this method, as shown in Figure 8, the discharge is completed inside the plasma generation unit 1b, and only the plasma jet 21b, which is a hot gas, is blown onto the object, while the plasma arc 22b does not act on the object. On the other hand, if a plasma arc can be applied to an artificial structure 8 made of an insulator such as concrete, the efficiency of peeling can be increased.

[0009] The present invention aims to provide an apparatus and method for peeling off the surface of a hard artificial structure made of asphalt, concrete, mortar, or the like by applying a plasma arc to the structure. [Means for solving the problem]

[0010] The present invention relates to a device for peeling off the surface of hard artificial structures made of asphalt, concrete, mortar, etc. The device comprises a plasma generating unit, a liquid supply unit for supplying an electrolyte to the surface of the artificial structure, and an electrode unit made of a conductive material and arranged in contact with the electrolyte. The device generates a discharge between the electrolyte applied to the surface of the artificial structure and the plasma generating unit to peel off the surface of the artificial structure, thereby solving the above problem.

[0011] The present invention relates to a method for peeling off the surface of a hard artificial structure made of asphalt, concrete, or mortar, and the method comprises the steps of supplying an electrolyte to the surface of the artificial structure so as to be in contact with an electrode made of a conductive material, and generating a discharge between the electrolyte applied to the surface of the artificial structure and a plasma generating unit, thereby solving the above problem.

[0012] In the aforementioned peeling apparatus and peeling method, a plasma arc can be applied to the artificial structure by using an electrolyte solution applied to the surface of the artificial structure. This allows for efficient peeling of the surface of the artificial structure.

[0013] The peeling device is equipped with a traveling mechanism and, while traveling, generates a discharge between the electrolyte applied to the surface of the artificial structure and a plasma generating unit to peel off the surface of the artificial structure.

[0014] The peeling device may be equipped with a sliding mechanism that reciprocates the plasma generating unit in a direction intersecting the direction of travel. By reciprocating the plasma generating unit in a direction intersecting the direction of travel using the sliding mechanism, the surface portion of an artificial structure can be peeled off in a region with a width in the direction intersecting the direction of travel.

[0015] In the peeling apparatus described above, the configuration may be such that the moving speed of the plasma generating unit when it reciprocates can be changed. For example, reducing the moving speed of the plasma generating unit prolongs the duration for which the plasma arc acts on any arbitrary location, increases the energy load at the arbitrary location, and makes it easier to peel off the surface portion. Further, for example, increasing the moving speed of the plasma generating unit reduces the energy load, and can reduce damage to the surface portion of an artificial structure.

[0016] In the peeling apparatus described above, the liquid supply unit may be a pipe-shaped member that supplies the electrolytic solution stored in the tank.

[0017] In the peeling apparatus described above, the electrode unit may be formed in a shape extending toward the surface portion of an artificial structure. Effects of the Invention

[0018] According to the present invention, there can be provided an apparatus and a method for peeling off a surface portion of a hard artificial structure made of asphalt, concrete, mortar, or the like by causing a plasma arc to act on the artificial structure. Brief Description of the Drawings

[0019] [Figure 1] It is a side view showing an example of the peeling apparatus. [Figure 2] It is a side view showing a state where a part of a front frame portion of the peeling apparatus in FIG. 1 is cut away. [Figure 3] It is an enlarged view of part A in FIG. 2. [Figure 4] It is a perspective view showing a state where a part of the peeling apparatus in FIG. 1 is viewed from diagonally above. [Figure 5] It is a perspective view showing an example of a slide mechanism. [Figure 6] It is a plan view showing an example of a mechanism for switching a moving direction. [Figure 7] It is an explanatory view showing a state where peeling treatment using plasma is performed on an artificial structure in the peeling apparatus of FIG. 1. [Figure 8] It is an explanatory diagram showing how plasma treatment using a plasma jet is performed. MODE FOR CARRYING OUT THE INVENTION

[0020] Hereinafter, an embodiment of a peeling apparatus for peeling a surface portion of an artificial structure according to the present invention (hereinafter sometimes simply referred to as a peeling apparatus or an apparatus) and a peeling method will be described. Each embodiment and use example shown below are merely limited examples of the present invention, and the technical scope of the present invention is not limited to the illustrated embodiments.

[0021] Figures 1 to 6 show an embodiment of the peeling apparatus 1. This peeling apparatus 1 peels a surface portion of a hard artificial structure 8 made of asphalt, concrete, mortar or the like. The peeling apparatus 1 includes a plasma generation unit 2, a liquid supply unit 3 that supplies an electrolytic solution 31 to the surface portion of the artificial structure 8, and an electrode unit 4 that is made of a conductive material and disposed so as to be in contact with the electrolytic solution 31. As will be described later, discharge is caused between the electrolytic solution 31 applied to the surface portion of the artificial structure 8 and the plasma generation unit 2 to peel the surface portion of the artificial structure 8.

[0022] The peeling apparatus 1 includes a plurality of wheels 51 as traveling means, and while traveling, causes discharge between the electrolytic solution 31 applied to the surface portion of the artificial structure 8 and the plasma generation unit 2 to peel the surface portion of the artificial structure 8. The plasma generation unit 2 and the electrolytic solution 31 are separated by gas, and discharge is generated in the gas. The traveling means is not limited to wheels as long as it can move the peeling apparatus. Examples of the traveling means include, in addition to wheels, endless tracks and the like.

[0023] The wheels 51 are fixed to the frame portion 5. Members including the plasma generation unit 2, a power supply unit 6 for the plasma generation unit 2, the liquid supply unit 3, a tank 7 connected to the liquid supply unit 3, a slide mechanism 9 (Figure 5) for reciprocating the plasma generation unit 2 in a direction intersecting the traveling direction, and a motor 914 which is a power source for reciprocating the plasma generation unit 2 left and right are attached to the frame portion 5.

[0024] A handle 52 is fixed to the frame 5. The operator grips the handle 52 and pushes the stripping device 1 to move it. The stripping device 1 may also be configured to be self-propelled by being equipped with a power source and power transmission mechanism for movement.

[0025] Figure 3 shows an enlarged side view of the plasma generation unit 2, the liquid supply unit 3, and the electrode unit 4. Figure 7 shows an example of the internal structure of the plasma generation unit.

[0026] The plasma generation unit 2 has a structure similar to that of a general plasma torch used for arc welding and metal plate processing. In this embodiment, as shown in Figure 7, the plasma generation unit 2 has a cylindrical electrode 21 and a jacket portion 22 for cooling the electrode 21. The jacket portion 22 is provided on the outside of the electrode 21. The electrode 21 is provided with a working gas supply hole 23. A known working gas is supplied to the supply hole 23, and while the working gas is ejected from the tip of the plasma generation unit 2 toward the surface of the artificial structure 8, a voltage is applied to the electrode 21 to generate a discharge between the electrode 21 and the electrolyte 31 applied so as to be in contact with the electrode portion 4, which will be described later. As a result, a plasma arc 24, which is a current path, is generated between the electrode 21 and the electrolyte 31, and a plasma jet 25 is generated around the plasma arc 24. The plasma jet 25 is the working gas ionized by the discharge. Examples of working gases include air, oxygen, a mixture of argon and hydrogen, nitrogen, or a mixture of these gases. Cooling water is supplied to the jacket section 22 to cool the plasma generation section 2. Alternatively, air cooling may be used instead of cooling.

[0027] The configuration of the plasma generation unit is not limited to the above example; for example, a known plasma torch used for metalworking by plasma may be used, which has an electrode made of tungsten or the like placed in the center of a cylindrical hollow tube.

[0028] As shown in Figure 3, the plasma generation unit 2 is fixed to a support unit 26 which has a mechanism for changing the angle of the plasma generation unit 2 and a lifting mechanism for adjusting the distance of the plasma generation unit 2 from the artificial structure 8. The plasma generation unit 2 and the power supply unit 6 are connected by a cable 53.

[0029] By rotating the first operating section 263 of the support section 26, the screw rod connected to the first operating section 263 moves up and down, and in conjunction with the screw rod, the plasma generating section 2 moves up and down. More specifically, the support section 26 consists of a first support section 261 and a second support section 262. The position of the first support section 261 is fixed, and by operating the first operating section 263, the second support section 262 moves up and down relative to the first support section 261. Since the plasma generating section 2 is fixed to the second support section 262, when the second support section 262 is moved up and down, the plasma generating section 2 moves in the vertical direction.

[0030] By operating the second operating section 264 of the support section 26, the second support section 262 rotates around the shaft section 265, and the angle of the plasma generating section 2 can be changed. As described above, the position of the first support section 261 is fixed, so by operating the second operating section 264, the second support section 262 rotates relative to the first support section 261.

[0031] The support portion 26 has a vertically elongated shape that extends along the direction of travel of the peeling device 1. One end of the support portion 26 is supported on a rail portion 54 provided on the frame portion 5, as shown in Figures 3 and 4, so as to be slidable in a direction intersecting the direction of travel of the device 1. The other end of the support portion 26 is fixed to a bracket 32 ​​for the liquid supply portion 3. The rail portion 54 is a rod-shaped member spanning the frame portion 5, and is composed of, for example, a member with an L-shaped cross-section.

[0032] As shown in Figure 3, the liquid supply section 3 is a pipe-shaped member that supplies the electrolyte stored in the tank 7. The liquid supply section branches into a Y-shape at its tip, supplying the electrolyte 31 to the surface of the artificial structure 8 from two locations: the left side of the plasma generation section 2 and the right side of the plasma generation section 2. The material constituting the liquid supply section 3 is not particularly limited, but is from the plasma generation section 2 or and others It is preferable to construct the unit from metal so that it can withstand the heat generated. Suitable metals include copper, which is easy to process, and stainless steel, which has excellent corrosion resistance. A known pump may be connected to the liquid supply unit 3 for the purpose of pressurizing the electrolyte 31 in the tank 7.

[0033] When supplying electrolyte from the fluid supply unit 3 to the surface of the artificial structure 8, it is preferable to drop the electrolyte 31 from the fluid supply unit 3. By supplying in this manner, it is possible to prevent a large amount of electrolyte from adhering to the plasma generation unit 2 when supplying the electrolyte 31 to the artificial structure 8, and to prevent substances contained in the electrolyte from solidifying on the plasma generation unit 2.

[0034] The fluid supply unit 3 is fixed to the bracket 32 ​​for the fluid supply unit 3 as described above. The bracket 32 ​​is plate-shaped. One end of the bracket 32 ​​is fixed to the support unit 26 as described above. The other end of the bracket 32 ​​is connected to the operating unit 92 of the slide mechanism 9, which will be described later.

[0035] The electrode portion 4 is made of a conductive material and, as shown in Figure 3, is positioned to be in contact with the electrolyte 31 applied to the surface of the artificial structure 8. The electrode portion 4 has a shape that extends toward the surface of the artificial structure 8. The conductive material constituting the electrode portion 4 can be, for example, easily processed copper or stainless steel with excellent corrosion resistance.

[0036] As shown in Figure 3, a linear member 41 made of a conductive material is fixed to the tip of the electrode portion 4. By bending the linear member 41 so that it comes into contact with the electrolyte 31, the electrode portion 4 can be made to come into contact with the electrolyte 31. In this way, when the electrode portion is arranged to come into contact with the electrolyte, it is assumed that the configuration includes making the electrode portion come into contact with the electrolyte via a conductive member such as a linear member. If the linear member 41 wears down due to contact with an artificial structure 8 or the like, the linear member 41 can be easily bent to adjust the electrode portion 4 so that it comes into contact with the electrolyte 31. If the linear member 41 becomes short, it can be replaced.

[0037] The base end of the electrode section 4 is fixed to the support section 26. The electrode section 4 is connected to the power supply section 6 via a cable 53 supported by the support section 26, forming a DC circuit. In this configuration, current flows from the power supply section 6, cable 53, electrode of the plasma generation section 2, electrolyte 31, electrode section 4, cable 53, and back to the power supply section 6. The circuit configuration is not limited to this; other configurations may be adopted as long as the power supply section, the electrode of the plasma generation section, and the electrode section form a circuit.

[0038] The peeling device 1 is equipped with a slide mechanism 9 that reciprocates the plasma generating unit 2 in a direction intersecting the direction of travel. The slide mechanism 9 is mounted on the frame 5 and, as shown in Figure 5, has a shaft 91 with a helical screw groove, an operating unit 92 that is screwed onto the shaft 91, and a support unit 93 that supports the shaft 91 and the operating unit 92. The operating unit 92 is connected to the bracket 32 ​​of the fluid supply unit 3.

[0039] As shown in Figure 5, the support portion 93 has multiple protrusions 931 corresponding to the grooves 921 provided in the operating portion 92. The operating portion 92 is roughly plate-shaped and has two grooves 921 on its back surface. There are also two protrusions 931. Plate-shaped projections 932 are fixed to both ends of the protrusions 931 in a direction intersecting the protrusions 931. A through hole is provided in the middle of the plate-shaped projection 932, supporting both ends of the shaft 91 in a rotatable state. The bottom of the support portion 26 is closed with a plate-shaped member 933. This plate-shaped member 933 is in contact with the protrusions 931 and projections 932.

[0040] A first pulley 911 is fixed to one end of the shaft 91 as a driven part. As shown in Figure 2, a drive belt 912 is wound around the first pulley 911. The other end of the belt 912 is wound around a second pulley 913, which is a drive part. The output shaft of a motor 914, which is a power source, is fixed to the second pulley 913. When the motor 914 is operated, the shaft 91 rotates via the second pulley 913, belt 912, and first pulley 911, causing the operating part 92 to move in a direction intersecting the direction of travel of the peeling device 1. The pulleys may be replaced with sprockets or bevel gears. The belt may also be replaced with a chain or a shaft connected to a bevel gear. In this way, the power source and the shaft 91 can be connected by various power transmission means.

[0041] The bracket 32 ​​for the liquid supply unit 3 is fixed to the operating unit 92. When the operating unit 92 moves, the bracket 32, the plasma generating unit 2, and the support unit 26 move together with it. As described above, the end of the support unit 26 is supported in a slidable manner on the rail unit 54 provided on the frame unit 5, so the plasma generating unit 2 moves smoothly in a direction intersecting the direction of travel of the device 1.

[0042] The plasma generating unit 2 moves together with the operating unit 92, which moves along the shaft 91. In order to make the plasma generating unit 2 reciprocate, it is necessary to switch the direction of movement of the plasma generating unit 2. Switching the direction of movement of the plasma generating unit 2 can be achieved by switching a physical switch, or a worm shaft may be used instead of the shaft 91, with two spiral grooves intersecting in an X shape on the circumferential surface of the shaft. Of the two spiral grooves provided on the worm shaft, the operating unit moves in one direction using one spiral groove, and moves in the other spiral groove. That is, by fitting a protrusion provided on the operating unit into the spiral groove and rotating the worm shaft in one direction, the operating unit changes direction at both ends of the shaft.

[0043] Figure 6 shows a mechanism 50 that switches the direction of movement of the plasma generation unit 2 by switching a physical switch. This mechanism has a pair of support parts 58 fixed to the frame part 5 and having through holes, a pair of shafts 591 that are slidably inserted through the through holes of the support parts 58, rod-shaped connecting parts 592 fixed to the left and right ends of the pair of shafts 591, and a switch part 57 fixed to the support part 58. The rod-shaped connecting parts 592 and the pair of shafts 591 are pushed by the plasma generation unit 2 and move together in the direction of movement of the plasma generation unit 2. The shafts 591 are fixed to protrusions 59 fixed to the connecting parts 592.

[0044] In Figure 6, the components indicated by diagonal lines, namely the support portion 58 and the switch portion 57, are fixed in position relative to the frame portion 5 and are immovable. When the plasma generating portion 2 moves to the right, as shown in the upper part of Figure 6, the plasma generating portion 2 contacts the end of the right shaft 591, causing the rod-shaped connecting portion 592 and the shaft 591 to move to the right, as indicated by the arrow. The connecting portion 592 is provided with a number of protrusions 571 that sandwich the operating portion of the switch portion 57. When the connecting portion 592 moves to the right, the protrusions 571 touch the operating portion, and the rotation direction of the motor, which is the power source, is switched. As a result, the plasma generating portion 2 changes direction to the left, that is, in the direction of arrow A in Figure 6.

[0045] When the plasma generating unit 2 moves to the left, it contacts the end of the left shaft 591, as shown in the lower part of Figure 6, and moves the rod-shaped connecting unit 592 and the shaft 591 to the left, as indicated by the arrow. The connecting unit 592 is provided with multiple protrusions 571 that sandwich the operating part of the switch unit 57. When the connecting unit 592 moves to the left, the protrusions 571 touch the operating part 92, and the rotation direction of the motor, which is the power source, is switched. As a result, the plasma generating unit 2 changes direction to the right, that is, in the direction of arrow B in Figure 6.

[0046] By repeating the above operation, the plasma generation unit 2 reciprocates from left to right. In the example shown in Figure 6, the support unit 58 is composed of a rod-shaped member that extends vertically through the device 1, with its end fixed to the frame unit 5. As a result, the mechanism 50 is positioned above or below the slide mechanism 9.

[0047] In the apparatus 1, the movement speed of the plasma generation unit 2 when it reciprocates can be changed. The movement speed can be changed by changing the rotation speed of the motor, which is the power source. In addition, the apparatus 1 is configured to allow the energy from the discharge to be changed. The energy from the discharge can be changed, for example, by controlling the voltage or current applied to the electrode 21. In the apparatus 1, these settings can be set on the control panel 915. By adjusting these settings, the strength of the peeling of the surface of the artificial structure 8 can be changed. The discharge type is preferably an arc discharge. In an arc discharge, strong light is emitted.

[0048] In the apparatus 1 described above, the plasma generating unit 2 reciprocates in a direction intersecting the direction of travel of the apparatus 1. The plasma generating unit 2 and the power supply unit 6 are connected by a cable 53. In the apparatus 1, a guide mechanism 56 for the cable 53 is provided, as shown in Figure 4, to prevent the cable 53 from becoming excessively taut when the plasma generating unit 2 reciprocates.

[0049] As shown in Figure 4, the guide mechanism 56 includes an arm-shaped member 561, one end of which is pivotally supported on the frame 5 in a rotatable manner, and the other end of which is provided with a holding portion 562 for holding the cable 53. When the cable 53 held by the holding portion 562 at the other end of the arm-shaped member 561 swings from side to side, the arm-shaped member 561 rotates from side to side around an axis provided at one end. This guides the cable 53 from side to side, preventing the cable 53 from getting caught on the device 1 or excessive tension from being applied to the cable. The holding portion has an arc-shaped plate-like portion formed to conform to the outer shape of the cable 53 and a slit hole for inserting the cable.

[0050] In the apparatus 1 described above, an electrolyte 31 is applied to an artificial structure 8 made of an insulator such as asphalt or concrete, and an electrode part 4 is provided that is in contact with the electrolyte 31, making it possible to pass an electric current through the electrolyte applied to the surface of the insulator. This generates a discharge between the electrolyte 31 applied to the surface of the artificial structure 8 and the plasma generating part 2, and by acting a plasma arc and plasma jet on the artificial structure 8, the surface of the artificial structure 8 can be efficiently peeled off.

[0051] In the stripping process, the amount of electrolyte supplied is less compared to the method of spraying water onto the artificial structure at high pressure. Therefore, the equipment and personnel required for the stripping process can be reduced, thereby saving labor.

[0052] Artificial structures are not particularly limited, but examples include road surfaces made of asphalt, ceilings, walls, or ground made of concrete or mortar. The surface of an artificial structure may or may not have paint attached to it, such as for traffic markings. If paint is attached, the existing paint can be removed. If paint is not attached, the surface of the artificial structure may be roughened by peeling the paint off in order to improve the adhesion of the paint.

[0053] The above-described peeling device 1 is configured to be driven by an operator pushing it. It may also be equipped with an automatic driving mechanism so that the device itself can move on its own. Furthermore, although the above-described peeling device is used to peel off traffic markings and other signs laid on the ground, its structure may be modified to peel off traffic markings and other signs installed on other artificial structures such as tunnel walls and building walls.

[0054] The electrolyte can be any liquid that conducts electricity. Examples of electrolytes include liquids containing any ions. The solvent is not particularly limited, but for example, water can be used. The solute is also not particularly limited, but for example, sodium chloride can be used. Seawater is preferably used as the electrolyte.

[0055] The above-described apparatus provides a method for peeling off the surface of a hard artificial structure made of asphalt, concrete, or mortar, and this method includes the steps of supplying an electrolyte to the surface of the artificial structure so as to be in contact with an electrode made of a conductive material, and generating a discharge between the electrolyte applied to the surface of the artificial structure and a plasma generating unit. [Explanation of Symbols]

[0056] 1. Peeling device 2 Plasma generation unit 3 Liquid supply section 4 Electrode part 8 Artificial structures 31 Electrolyte 9. Slide mechanism 7 tanks

Claims

1. This is a device for removing paint applied to the surface of hard artificial structures made of asphalt, concrete, or mortar, etc. The device comprises a plasma generation unit and A liquid supply unit that supplies electrolyte to the surface of an artificial structure, It has an electrode portion made of a conductive material and arranged to be in contact with the electrolyte, The electrodes of the plasma generating unit are not in contact with the electrolyte and are separated from the surface of the hard artificial structure. The stripping device is equipped with a traveling mechanism and, while traveling over an artificial structure, generates a plasma arc and a plasma jet through discharge between the electrolyte applied to the surface of the artificial structure and the electrodes of a plasma generating unit separated from the electrolyte and the hard surface of the artificial structure, thereby stripping the paint applied to the surface of the artificial structure. The plasma jet is formed by ionizing the working gas supplied into the plasma generation unit, and is ejected from the plasma generation unit toward the surface of an artificial structure as a peeling device.

2. The peeling apparatus according to claim 1, further comprising a sliding mechanism that reciprocates a plasma generating unit in a direction intersecting the direction of travel.

3. The peeling apparatus according to claim 2, wherein the movement speed of the plasma generating unit when it moves back and forth can be changed.

4. The peeling device according to claim 1, wherein the liquid supply section is a pipe-shaped member that supplies electrolyte stored in a tank.

5. The peeling apparatus according to claim 1 or 2, wherein the electrode portion has a shape that extends toward the surface of the artificial structure.

6. A method for removing paint applied to the surface of a hard artificial structure made of asphalt, concrete, or mortar, etc. The method includes the step of supplying an electrolyte solution to the surface of an artificial structure so as to come into contact with an electrode made of a conductive material, The process involves running a peeling device having a plasma generating unit over an artificial structure, while generating a plasma arc and a plasma jet by discharge between an electrolyte applied to the surface of the artificial structure and the electrodes of the plasma generating unit separated from the electrolyte and the hard surface of the artificial structure. The aforementioned plasma jet is generated when the working gas supplied to the plasma generation unit is ionized and ejected from the plasma generation unit toward the surface of the artificial structure. A method for removing paint applied to the surface of an artificial structure, wherein the electrodes of the plasma generating unit are not in contact with the electrolyte and are not in contact with the surface of the hard artificial structure.

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