Coating film removal method and coating film removal apparatus

Abstract

To provide a coating film removal method and a coating film removal device that can remove a coating film of a coating applied to a surface of a structural member in an existing structure and can reduce changes in shape or composition acting on a base adjustment surface even when a laser beam is irradiated on the base adjustment surface of the structural member.SOLUTION: The coating film removal device includes: a laser oscillator 2; a laser head 4 for irradiating a steel material W with a laser beam L supplied from the laser oscillator 2; a scanning mechanism 6 for scanning a surface of the steel material W with the laser beam L from the laser head 4; and a control unit 10 for controlling the output and spot diameter of the laser beam L irradiated from the laser head 4 and the scanning speed of the laser beam L by the scanning mechanism 6. The control unit 10 controls the laser head 4 and the scanning mechanism 6 under laser conditions set to leave unevenness existing in a base adjustment surface Wa of the steel material W.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a coating film removal method and a coating film removal device suitable for removing a coating film applied to the surface of a structural member in an existing structure such as a bridge or a building.

Background Art

[0002] In order to safely use the above-mentioned existing structures such as bridges and buildings over a long period of time, it is necessary to periodically peel off and remove the coating film applied to the surface of the steel material (structural member) to prevent corrosion of the steel material and then reapply the coating.

[0003] Conventionally, as a method for removing the coating film on the surface of a steel material, for example, there is a coating film removal method described in Patent Document 1. In this coating film removal method, the coating film is removed by moving the laser head horizontally with respect to the steel material while circularly scanning the irradiation point of the laser light irradiated from the laser head.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the coating film removal method using laser light as described above, relatively high-power laser light is adopted in order to improve the peelability of the coating film.

[0006] However, if the high-power laser light is continuously irradiated on the portion where the coating film has been removed, the minute irregularities of several micrometers existing on the substrate adjustment surface of the steel material before coating will almost disappear.

[0007] Thus, when the minute unevenness on the surface conditioning surface of the steel material disappears, at the stage of repainting after the coating film is removed, the adhesion of the newly applied coating film to the surface conditioning surface becomes weak, and there is a risk that the durability of the painted surface may decrease.

[0008] Therefore, even if laser light is irradiated on a portion where the coating film has been removed, it is desired to construct laser conditions that can minimize excessive shape changes such as the disappearance of minute unevenness on the surface conditioning surface of the steel material and changes in the composition of the surface conditioning surface, and solving this has been a conventional problem.

[0009] The present disclosure has been made to solve the above-described conventional problems, and can not only remove the coating film applied to the surface of the structural member in the existing structure, but also minimize the changes in shape and composition exerted on the surface conditioning surface of the structural member even when laser light is irradiated on the surface conditioning surface of the structural member. An object is to provide a coating film removing method and a coating film removing apparatus.

Means for Solving the Problems

[0010] A first aspect of the present disclosure is a coating film removing method for removing a coating film applied on a surface conditioning surface of a structural member of an existing structure is bridge beam or is steel constituting a steel tower material When scanning while irradiating the coating film with laser light under laser conditions set to leave the unevenness present on the surface conditioning surface of the structural member, the laser conditions are such that the output of the laser light is 1000 W or less, and the fluence, which is the amount obtained by dividing the output of the laser light by the product of the spot diameter of the laser light and the scanning speed of the laser light, is 0.13 to 0.15 J / mm 2 For this purpose, the scanning speed of the laser light is set to 9.0 to 15.0 m / s.

[0011] Further, a second aspect of the present disclosure is configured to linearly scan while irradiating the coating film with laser light.

[0014] On the other hand, the first of the present disclosure3 The aspect is the structural member of the existing structure is Bridge beam or is the steel that constitutes the iron tower material A coating film removing device for removing a coating film applied on a base adjustment surface in, comprising a laser oscillator, a laser head that irradiates the structural member with laser light supplied from the laser oscillator, a scanning mechanism that scans the laser light from the laser head on the surface of the structural member, and a control unit that controls the output, spot diameter of the laser light irradiated from the laser head, and the scanning speed of the laser light by the scanning mechanism. The control unit controls the laser head and the scanning mechanism under laser conditions set to leave unevenness existing on the base adjustment surface of the structural member. The laser conditions are that the output of the laser light is 1000 W or less, and the fluence, which is the amount obtained by dividing the output of the laser light by the product of the spot diameter of the laser light and the scanning speed of the laser light, is 0.13 to 0.15 J / mm 2 In order to make it, the scanning speed of the laser light is set to 9.0 to 15.0 m / s.

[0015] In the coating film removing method and the coating film removing device according to the present disclosure, although it is common to use a fiber laser, a semiconductor laser, a YAG laser, etc. for the laser, it is not limited to these lasers.

Effect of the Invention

[0016] According to the coating film removing method and the coating film removing device according to the present disclosure, it goes without saying that the coating film of the coating applied to the surface of the structural member in the existing structure can be removed. Even when the base adjustment surface of the structural member is irradiated with laser light, a very excellent effect is brought about that it is possible to suppress a decrease in the shape and composition changes exerted on the base adjustment surface.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 shows a laser coating removal apparatus used for the coating removal method according to an embodiment of the present disclosure.

[0019] As schematically shown in FIG. 1, this laser coating removal apparatus 1 is for peeling and removing a coating film Wm applied to the surface of a steel material (structural member) W constituting a bridge, and includes a laser oscillator 2, a laser head 4 that condenses the laser light L supplied from the laser oscillator 2 by the built-in optical system 3 and irradiates the surface of the steel material W, an optical fiber 5 that guides the laser light L from the laser oscillator 2 to the laser head 4, a scanning mechanism 6 that scans the laser light L from the laser head 4 on the surface of the steel material W, and a control unit 10 that controls the output of the laser light L irradiated from the laser head 4, the spot diameter of the laser light L, the scanning speed of the laser light L by the scanning mechanism 6, and the like.

[0020] The scanning mechanism 6 is held in the case 9 together with the laser head 4, and includes a scanner mirror 6a that reflects the laser light L from the laser head 4 and a scanner motor 6b that rotates the scanner mirror 6a within a predetermined range.

[0021] In this embodiment, the laser beam L from the laser head 4 is reflected by the scanner mirror 6a toward the steel material W, and by rotating this scanner mirror 6a within a predetermined range, as shown in FIG. 2, the laser beam L is linearly scanned (reciprocated in a zigzag pattern) on the surface of the steel material W to remove the coating film Wm.

[0022] In this case, the control unit 10 controls the laser head 4 and the scanner motor 6b of the scanning mechanism 6 under laser conditions set such that even when the laser beam L irradiates the base adjustment surface Wa of the steel material W, the unevenness present on the base adjustment surface Wa remains.

[0023] When determining the above laser conditions, first, if the output of the laser beam L is set too high, the minute unevenness of the base adjustment surface Wa will disappear regardless of other conditions. Therefore, the upper limit of the output of the laser beam L is set to 1000 W.

[0024] The energy density (W / mm 2 ) obtained by dividing the output of the laser beam L by the area SA of the spot S of the laser beam L shown in FIG. 3 increases as the spot diameter D becomes smaller, and the heat input per unit time increases. Therefore, the spot diameter D is set to 0.15 mm and the energy density is set to be on the larger side to ensure reliable removal of the coating film.

[0025] Also, the fluence, which is the amount obtained by dividing the output of the laser beam L by the product of the spot diameter D of the laser beam L and the scanning speed V (m / s) of the laser beam L shown in FIG. 3 (scanning area A (m 2 / s)), is desirably 0.2 J / mm 2 or less, more desirably 0.15 J / mm 2 or less, and even more desirably 0.13 J / mm 2 or less.

[0026] Here, the relationship between the output of the laser beam L corresponding to various fluences and the scanning area A of the laser beam L is shown in FIG. 4. As can be seen from the graph of FIG. 4, in the relationship between the output of the laser beam L and the scanning area A of the laser beam L, the fluence is represented as the slope of each of the reference lines I to III. In the present embodiment, the fluence is 0.13 J / mm 2 Taking the reference line I with a slope of as an index, the energy density and the scanning speed V of the laser beam L are set so that the output of the laser beam L and the scanning area A of the laser beam L are respectively located on or near this reference line I.

[0027] Thereby, in order to make the fluence 0.13 to 0.15 J / mm 2 the scanning speed V of the laser beam L is desirably set to 9.0 m / s or more, more desirably 12.0 m / s or more, and even more desirably 15.0 m / s or more.

[0028] Thus, in the present embodiment, the control unit 10 sets the upper limit of the output of the laser beam L to 1000 W and the spot diameter D to 0.15 mm, and then, in order to make the fluence 0.13 to 0.15 J / mm 2 the scanner motor 6b of the scanning mechanism 6 is controlled so that the scanning speed of the laser beam becomes 9.0 to 15.0 m / s.

[0029] Therefore, under the condition No. 1 shown in Table 1 set with the reference line I as an index and the condition No. 2 set with the reference line II as an index, the coating film Wm applied to the surface of the steel material W constituting the bridge was removed. As an example in which minute unevenness on the substrate adjustment surface disappears regardless of various conditions, the case of condition No. 3 set based on the reference line III is also described in Table 1 (surface state (×) in Table 1).

[0030]

Table 1

[0031] In the removal of the coating film according to Condition No. 1, the results shown in Fig. 5 were obtained. On the other hand, in the removal of the coating film according to Condition No. 2, the results shown in Fig. 6 were obtained.

[0032] As can be seen from Fig. 5, in the removal of the coating film according to Condition No. 1, the degree of shading of the substrate adjustment surface is "dark". This indicates that a large number of minute irregularities existing on the substrate adjustment surface remain (surface state (〇) in Table 1). In contrast, as can be seen from Fig. 6, in the removal of the coating film according to Condition No. 2, the degree of shading of the substrate adjustment surface is "light". This indicates that the minute irregularities existing on the substrate adjustment surface have almost disappeared (surface state (△) in Table 1).

[0033] Therefore, according to the coating film removal method and the coating film removal apparatus according to the present embodiment, it has been demonstrated that the coating film Wm of the coating applied to the surface of the steel material W can be removed while suppressing as little as possible the changes in shape and composition exerted on the substrate adjustment surface Wa.

[0034] In the above-described embodiment, the case where the coating film Wm applied to the surface of the steel material (structural member) W constituting the bridge is removed by the coating film removal method and the coating film removal apparatus according to the present disclosure has been shown. However, the present disclosure is not limited thereto, and it is naturally possible to apply the coating film removal method and the coating film removal apparatus according to the present disclosure to, for example, the removal of the coating film of the steel material constituting the iron tower.

[0035] The configurations of the coating film removal method and the coating film removal apparatus according to the present disclosure are not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present disclosure.

Description of Reference Numerals

[0036] 1 Laser coating film removal apparatus (coating film removal apparatus) 4 Laser head 6 Scanning mechanism 6a Scanner mirror 6b Scanner motor 10 Control unit L Laser light W Steel material (structural member) Wa Substrate adjustment surface Wm coating film

Claims

1. A method for removing a coating film applied on a substrate adjustment surface of a steel material constituting a bridge or a tower, which is a structural member of an existing structure, comprising: When scanning while irradiating the coating film with laser light under laser conditions set to leave irregularities existing on the substrate adjustment surface of the structural member, The laser conditions are such that the output of the laser light is 1000 W or less, and the fluence, which is the amount obtained by dividing the output of the laser light by the product of the spot diameter of the laser light and the scanning speed of the laser light, is 0.13 to 0.15 J / mm ２ A coating film removal method in which the scanning speed of the laser light is set to 9.0 to 15.0 m / s in order to achieve the above conditions.

2. The coating film removing method according to claim 1, wherein scanning is performed linearly while irradiating the coating film with laser light.

3. A coating film removing device for removing a coating film applied on a substrate adjustment surface of a steel material constituting a bridge or a tower, which is a structural member of an existing structure, comprising: A laser oscillator; A laser head for irradiating the structural member with laser light supplied from the laser oscillator; A scanning mechanism for scanning the laser light from the laser head on the surface of the structural member; A control unit for controlling the output, spot diameter of the laser light irradiated from the laser head, and the scanning speed of the laser light by the scanning mechanism, The control unit controls the laser head and the scanning mechanism under laser conditions set to leave irregularities existing on the substrate adjustment surface of the structural member. The laser conditions are such that the output of the laser beam is 1000 W or less, and the fluence, which is the amount obtained by dividing the output of the laser beam by the product of the spot diameter of the laser beam and the scanning speed of the laser beam, is 0.13 to 0.15 J / mm ２ A coating film removing apparatus in which the scanning speed of the laser beam is set to 9.0 to 15.0 m / s in order to achieve the above conditions.

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