Roughening method by laser irradiation

Abstract

Even if the device configuration and processing parameters differ for each laser light irradiation device, processing conditions can be easily determined and processing can be performed. [Solution] A method for roughening a surface by laser irradiation is provided, which includes the steps of: roughening a test piece made of steel by laser irradiation; acquiring the surface roughness, roughening depth, and rough surface peak spacing of the roughened test piece; determining whether Sm / Rz, which is the ratio of the average surface roughness Rz, which indicates the rough surface depth at any 10 points of the roughened surface, to the average spacing Sm between rough surface peaks, satisfies a predetermined numerical value; determining the type and content of parameters, which are processing conditions for laser irradiation, to be instructed to an operator based on the results of the ratio determination; and outputting the determined instructions, in which the determination step determines whether the ratio satisfies Sm / Rz≦5.

Description

[Technical Field]

[0001] The present invention relates to a method for forming a rough surface by laser irradiation. [Background technology]

[0002] Conventionally, zinc-plated steel materials used in steel towers, such as those used in power transmission facilities, have been subjected to anti-rust coating as a general lifespan measure to combat wear and tear over time. In particular, when the zinc plating has disappeared due to significant deterioration, the steel material must be replaced. To avoid this, metal spray coatings with anti-rust properties equivalent to or greater than those of hot-dip galvanization are formed on-site. In these metal spraying methods, the surface of the steel material is roughened to create an uneven surface to ensure adhesion of the metal coating to the substrate. For example, a known anti-rust spraying method involves spraying abrasive material (abrasive) at high speed to remove rust and corrosion products, creating a rough surface, and then spraying molten metal from an arc welder onto the surface to restore the anti-rust properties.

[0003] Thermal spray blasting is a known blasting method in which a blasting material is projected onto the surface of steel to roughen it (see, for example, Patent Document 1). In the thermal spray blasting method, a highly hard abrasive is used directly onto the substrate to be thermally sprayed, and the blast abrasive is projected with great pressure to create a rough surface that firmly adheres the thermal spray coating to the substrate. This results in large irregularities and scratches on the substrate to be thermally sprayed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 07-000825 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of the conventional blasting process described above, the abrasives generated by the process scatter around, so the work site needs to be sufficiently protected, which increases costs. In particular, when the work is performed at high altitudes such as on steel towers, it takes time and effort to install the protection equipment. In addition, the generated abrasives also need to be collected.

[0006] A method is known in which a laser beam is used to irradiate the surface of a steel material with a laser to remove only the rust on the surface of the steel material. Although it is conceivable to roughen the surface of the steel material by irradiating the laser with such a laser beam irradiation device, a high-output laser beam irradiation device is required to form deep irregularities in the steel material, which is the substrate to be thermally sprayed. In other words, when roughening is performed by laser irradiation in the roughening process before rust prevention thermal spraying, the device configuration and processing parameters differ depending on the laser light irradiation device used, so it is time-consuming to determine in advance the processing conditions that are suitable for all laser light irradiation devices, and it is difficult to perform the irradiation process under appropriate processing conditions, so there is room for improvement in this regard.

[0007] The present invention has been made in consideration of these circumstances, and its purpose is to provide a method for roughening a surface by laser irradiation that allows processing conditions to be easily determined and processing to be performed, even if the device configuration and processing parameters differ for each laser light irradiation device. [Means for solving the problem]

[0008] (1) Aspect 1 of the method for forming a rough surface by laser irradiation according to the present invention is characterized by comprising the steps of: roughening a test piece made of steel by laser irradiation; acquiring the surface roughness, roughening depth, and rough surface peak spacing of the roughened test piece; determining whether Sm / Rz, which is the ratio of the average surface roughness Rz indicating the rough surface depth at any 10 points of the roughened surface to the average spacing Sm between rough surface peaks, satisfies a predetermined numerical value; determining the type and content of parameters, which are processing conditions for laser irradiation to be instructed to an operator, based on the determination result of the ratio; and outputting the determined instructions.

[0009] According to the method for forming a roughened surface by laser irradiation of the present invention, the average surface roughness Rz and the average spacing between roughened surface peaks Sm are obtained by previously roughening a test piece by irradiating a laser with a laser beam irradiation device to be used, and it is determined whether the ratio of the average surface roughness Rz to the average spacing between roughened surface peaks Sm (Sm / Rz) satisfies a predetermined value. Based on this determination result, the types and contents of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, can be determined. This procedure makes it easy to determine processing conditions suitable for each laser beam irradiation device to be used, so even if the device configuration and processing parameters differ for each laser beam irradiation device, processing conditions for forming the optimal roughened surface required for rust-preventive thermal spraying can be set in advance for each laser beam irradiation device. Furthermore, according to the method for roughening a surface by laser irradiation of the present invention, the roughening process can be performed by laser irradiation, which eliminates the need for time-consuming work such as installing protective equipment to prevent abrasives from scattering, or recovering the abrasives, as in conventional blasting methods, thereby reducing costs and improving work efficiency.

[0010] (2) A second aspect of the present invention may be characterized in that in the method for forming a rough surface by laser irradiation according to the first aspect, the determining step determines whether the ratio satisfies mathematical formula (1).

[0011]

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[0012] In this case, by determining that the ratio (Sm / Rz) of the average surface roughness Rz to the average spacing between rough surface peaks Sm is 5 or less, the types and contents of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, can be specifically and reliably determined.

[0013] (3) In a third aspect of the present invention, in the method for forming a rough surface by laser irradiation according to the second aspect, if the evaluation result satisfies the formula (1), metal spraying is carried out based on the determined instructions, and if the formula (1) is not satisfied and Sm / Rz is greater than 5, it is preferable to adjust at least one of the values ​​of the average surface roughness Rz and the average spacing between rough surface peaks Sm.

[0014] In this case, if the formula (1) is not satisfied in the judgment process, the type and content of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, can be specifically and reliably determined by adjusting at least one of the values ​​of the average surface roughness Rz and the average spacing between rough surface peaks Sm.

[0015] (4) In a fourth aspect of the present invention, in the method for forming a rough surface by laser irradiation of the second aspect, when adjusting the value of the average surface roughness Rz, it is preferable to adjust at least one of the output and focal length of the laser irradiation.

[0016] In this case, the value of the average surface roughness Rz can be adjusted by adjusting at least one of the output power and focal length of the laser irradiation, and processing conditions suitable for the laser light irradiation device to be used can be easily determined.

[0017] (5) In aspect 5 of the present invention, in the method for forming a rough surface by laser irradiation of aspect 3 or aspect 4, when adjusting the value of the average spacing Sm between rough surface peaks, it is preferable to adjust at least one of the speed and width of the laser irradiation.

[0018] In this case, by adjusting at least one of the speed and width of the laser irradiation, the value of the average spacing Sm between rough surface peaks can be adjusted, and processing conditions suitable for the laser light irradiation device to be used can be easily determined. [Effects of the Invention]

[0019] According to the method for roughening a surface by laser irradiation of the present invention, even if the device configuration and processing parameters differ for each laser light irradiation device, processing conditions can be easily determined and processing can be performed. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view showing a method for forming a rough surface by laser irradiation according to an embodiment of the present invention. [Figure 2] FIG. 1 is a cross-sectional view of a steel material that has been coated with an anti-rust coating by a surface roughening method. [Figure 3] 1(a) to 1(d) are diagrams showing a construction procedure up to rust prevention coating, including a method of roughening a surface by laser irradiation. [Figure 4] FIG. 1 is a flowchart showing a method for forming a rough surface by laser irradiation. [Figure 5] FIG. 10 is a diagram illustrating the average spacing between rough surface peaks. [Figure 6] FIG. 2 is a diagram illustrating average surface roughness. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the method for roughening a surface by laser irradiation according to the present invention will be described with reference to the drawings. Note that in each drawing, the scale of each component may be appropriately changed as necessary to make each component large enough to be visible.

[0022] The method of roughening a surface by laser irradiation according to this embodiment is generally adopted for applying anti-rust coating as a life extension measure to prevent wear and deterioration over time of galvanized steel materials used in steel towers for power transmission facilities, etc.

[0023] Figure 1 shows a state in which a surface 2a of a steel material 2 (test piece) is roughened by laser irradiation using a laser beam irradiation device 1. Figure 2 shows a cross section of the steel material after it has been coated with an anti-rust coating by the surface roughening method. As shown in Fig. 2, a processed portion 20 of a steel material 2 that has been anti-rust coated by the surface roughening method according to this embodiment is processed on a roughened surface 20a that has been irradiated with a laser beam using a laser beam irradiation device 1. In this embodiment, an L-shaped steel is used as the steel material 2. The anti-rust coating is applied to the entire surface of the steel material 2. The processed portion 20 has a metal spray coating layer 21, a sealing treatment layer 22, an undercoat paint layer 23A, and a topcoat paint layer 23B laminated in this order from the roughened surface 20a.

[0024] The metal spray coating layer 21 is formed by spraying molten metal with an arc welder. The sealing treatment layer 22 is provided so as to cover the surface of the metal sprayed coating layer 21, and is treated to protect the surface of the metal sprayed coating layer 21 and fill minute voids on the surface. The anti-rust coating layer 23 (undercoat paint layer 23A and topcoat paint layer 23B) has been treated to enhance anti-rust and weather resistance.

[0025] Figures 3(a) to (d) show the construction procedure up to the application of anti-rust coating, including the method of roughening the surface by laser irradiation. As shown in Figure 3(a), first, a laser beam irradiation device 1 is used to perform a roughening treatment step in which the entire surface 2a of an existing steel material 2 to be subjected to anti-rust coating is irradiated with a laser beam to roughen the surface. The laser beam irradiation device 1 moves so that the laser beam 1a is irradiated onto the entire surface 2a of the steel material 2. The reference symbol 2b shown in Figure 3(a) indicates the roughened surface formed by laser irradiation. A specific method for forming a roughened surface by laser irradiation will be described later.

[0026] 3(b), an anti-rust spraying step is performed in which anti-rust spraying is performed on the rough surface 2b of the steel material 2 to form a metal sprayed coating layer 21. In the anti-rust spraying step, metal 3a melted by an arc welder 3 is sprayed onto the rough surface 2b of the steel material 2 to form the metal sprayed coating layer 21. The electric arc spraying used in the anti-corrosion thermal spraying process is low voltage and low temperature, and uses a metal coating, for example, an aluminum (Al)-magnesium (Mg) alloy (Al: 95%, Mg: 5%). The standard spray coating thickness is, for example, 150 μm. In the rust prevention thermal spraying process, metal spraying can be performed using spraying equipment and methods such as gas flame spraying and plasma wire spraying in addition to the electric arc spraying described above.

[0027] 3(c), a sealing step is performed in which a sealing layer 22 is provided so as to cover the surface of the metal spray coating layer 21. In the sealing step, the sealing layer 22 is formed by applying a sealing material that protects the surface of the metal spray coating layer 21 and fills minute voids on the surface.

[0028] 3(d), an anti-rust coating step is performed in which an anti-rust coating layer 23 is provided so as to cover the surface of the sealing treatment layer 22. In the anti-rust coating step, the anti-rust coating layer 23 is formed by applying an anti-rust treatment material to enhance rust prevention and weather resistance.

[0029] Next, the method for forming a rough surface by laser irradiation will be specifically described. Fig. 4 shows a flowchart of the method for forming a rough surface by laser irradiation. The method for forming a rough surface is a method for carrying out the above-mentioned surface roughening treatment step. First, in step S1, a test piece made of steel is roughened to have an uneven surface by irradiating laser light using a laser light irradiation device 1 (see FIG. 3(a)).

[0030] The laser irradiation in this case may be a pulsed wave or a continuous wave. A high-output laser beam irradiation device 1 is used, and a pulsed wave is more likely to form deep irregularities with less output, and a shorter irradiation distance makes it easier to create deep irregularities. Examples of the laser beam irradiation device 1 used for roughening include a laser cleaning device, laser cleaner, laser scraper, and laser blaster. When the laser light irradiation output is, for example, 100 W to 500 W, a pulse wave is preferred, and when the laser light irradiation output is high, such as 500 W to 3000 W or more, both pulse wave and continuous wave waveforms are possible, but continuous waves can more quickly and easily roughen the uneven surface.

[0031] Next, the surface roughness, roughening depth, and rough surface peak spacing of the roughened test piece are obtained (Step S2). These surface roughnesses are measured using a roughness meter (surface roughness measuring instrument). As a roughness meter, for example, a "small surface roughness measuring instrument" (SURFTEST SJ-310 series, manufactured by Mitutoyo Corporation) with a measurement range of the X axis (16 mm) and Z1 axis (surface roughness 360 μm [-200 to +160]) can be used.

[0032] Next, in step S3, it is determined whether the average surface roughness Rz and the average spacing Sm between roughened surface peaks, which indicate the depth of the roughened surface at any 10 points on the roughened surface, satisfy the formula (1).

[0033]

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[0034] Here, the mean spacing between peaks on the rough surface, Sm, is calculated by adding up the lengths of the mean lines (Sm1, Sm2, ... Smi, Smn) corresponding to one peak and one adjacent valley in the reference length, as shown in Figure 5, and the arithmetic mean value of these many peaks and valleys is called Sm (μm) (see formula (2)). However, if there are regulations regarding the minimum height and minimum length, and the height (depth) is 10% or less of the maximum value, or the length is 1% or less of the calculation range, it is considered to be noise and part of the peak or valley before and after.

[0035]

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[0036] The average surface roughness Rz is the 10-point average surface roughness, and as shown in Figure 6, the measurement curve is divided into reference lengths, and Rz is calculated by summing the average of the absolute values ​​from the highest peak Yp1 to the fifth peak Yp5 from the average line (m) at each reference length and the average of the absolute values ​​of the heights from the lowest valley bottom Yv1 to the fifth valley bottom Yv5.

[0037]

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[0038] In formula (1), if the value of Sm / Rz is greater than 5, the adhesive strength between the metal spray coating layers is very high and cohesive failure of the sprayed layer does not occur, so that in a normal tensile strength test of the sprayed coating, interfacial failure always occurs first between the substrate to be sprayed and the sprayed coating, leading to peeling. In other words, if the value of Sm / Rz is 5 or less, an ideal uneven, rough surface condition for the metal spray coating can be created on the substrate to be sprayed, which reliably improves the adhesive strength of the metal spray coating and ensures stable coating adhesive strength.

[0039] Then, in step S4, the type and content of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, are determined based on the determination result of the formula (1), and the determined instruction content is output.

[0040] If the determination result in step S3 satisfies formula (1) (Sm / Rz≦5, step S3: Yes), the process proceeds to step S4, where metal spraying is carried out based on the determined instructions. If Sm / Rz is greater than 5 (Sm / Rz>5, step S3: No) without satisfying formula (1), proceed to step S5, where at least one of the average surface roughness Rz and the average spacing between rough surface peaks Sm is adjusted.

[0041] Specifically, when adjusting the value of the average surface roughness Rz in step S5 (step S6), at least one of the output of the laser irradiation and the focal length is adjusted. For example, when increasing the value of the average surface roughness Rz, the output of the laser light irradiation device is adjusted to be increased, or the focal length is adjusted to be shortened by changing the lens. On the other hand, when decreasing the value of the average surface roughness Rz, the output of the laser light irradiation device is adjusted to be decreased, or the focal length is adjusted to be longer by changing the lens.

[0042] In step S5, when the value of the rough surface mean inter-peak spacing Sm is adjusted (step S7), at least one of the speed and width of the laser irradiation is adjusted. For example, when the value of the rough surface mean inter-peak spacing Sm is increased, the speed of the laser irradiation is adjusted to be faster or the width of the laser irradiation is adjusted to be wider. On the other hand, when the value of the rough surface mean inter-peak spacing Sm is decreased, the speed of the laser irradiation is adjusted to be slower or the width of the laser irradiation is adjusted to be narrower.

[0043] Then, after the Sm value and Rz value are adjusted in steps S6 and S7, the process returns to step S1.

[0044] The above-described method for roughening a surface by laser irradiation can be realized by using a calculation program executed by a computer. That is, the calculation program for the method for roughening a surface executes the following steps: Step S1: roughening a steel test piece by laser irradiation using a laser beam irradiation device 1 to form an irregular surface; Step S2: acquiring the surface roughness, roughening depth, and rough surface peak spacing of the roughened test piece; Step S3: determining whether the average surface roughness Rz and the average peak spacing Sm, which indicate the roughening depth at any 10 points of the roughened surface, satisfy Formula (1); and Step S4: determining the types and contents of parameters, which are the processing conditions for laser irradiation to be instructed to the operator, based on the determination result of Formula (1), and outputting the determined instructions. In this case, a computer (CPU or MPU) (not shown) is provided that stores and executes a calculation program for the method of forming a rough surface by laser irradiation.

[0045] Next, the effect of the method for forming a rough surface by laser irradiation will be described in detail. The method for forming a rough surface by laser irradiation according to this embodiment includes the steps of roughening a test piece made of steel 2 by laser irradiation, acquiring the surface roughness, roughening depth, and rough surface peak spacing of the roughened test piece, determining whether Sm / Rz, which is the ratio of the average surface roughness Rz indicating the rough surface depth at any 10 points of the roughened surface to the average spacing Sm between rough surface peaks, satisfies a predetermined numerical value, determining the type and content of parameters, which are the processing conditions for laser irradiation to be instructed to an operator, based on the determination result of the ratio (Sm / Rz), and outputting the determined instruction content.

[0046] According to this embodiment, the average surface roughness Rz and the average spacing between rough surface peaks Sm are obtained by previously roughening a test piece by irradiating the test piece with a laser using the laser beam irradiation device 1 to be used, and it is determined whether the ratio (Sm / Rz) of the average surface roughness Rz to the average spacing between rough surface peaks Sm satisfies a predetermined value. Based on this determination result, the types and contents of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, can be determined. This procedure makes it easy to determine the processing conditions suitable for each laser beam irradiation device 1 to be adopted, so even if the device configuration and processing parameters differ for each laser beam irradiation device 1, the processing conditions for forming the optimal roughened surface required for rust-preventive thermal spraying can be set in advance for each laser beam irradiation device 1. Furthermore, in this embodiment, the roughening process can be performed by laser irradiation, which eliminates the need for time-consuming work such as installing protective equipment to prevent abrasives from scattering, as in conventional blasting methods, and recovering the abrasives, thereby reducing costs and improving work efficiency.

[0047] In this embodiment, in the determining step, it is determined whether the ratio Sm / Rz satisfies the formula (1). Therefore, by determining that the ratio (Sm / Rz) of the average surface roughness Rz to the average spacing between rough surface peaks Sm is 5 or less, the types and contents of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, can be specifically and reliably determined.

[0048] Furthermore, in the method for forming a rough surface by laser irradiation according to this embodiment, if the judgment result satisfies formula (1), metal spraying is carried out based on the determined instructions, and if formula (1) is not satisfied and Sm / Rz is greater than 5, at least one of the values ​​of the average surface roughness Rz and the average spacing between rough surface peaks Sm is adjusted. Therefore, if the formula (1) is not satisfied in the judgment process, the type and content of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, can be specifically and reliably determined by adjusting at least one of the values ​​of the average surface roughness Rz and the average spacing between rough surface peaks Sm.

[0049] In the method for forming a rough surface by laser irradiation according to this embodiment, when adjusting the value of the average surface roughness Rz, at least one of the output power and focal length of the laser irradiation is adjusted. Therefore, by adjusting at least one of the output power and focal length of the laser irradiation, the value of the average surface roughness Rz can be adjusted, and processing conditions suitable for the laser beam irradiation device 1 to be used can be easily determined.

[0050] In the method for forming a rough surface by laser irradiation according to this embodiment, when adjusting the value of the mean inter-peak spacing Sm of the rough surface, at least one of the speed and width of the laser irradiation is adjusted. Therefore, by adjusting at least one of the speed and width of the laser irradiation, the value of the mean spacing Sm between rough surface peaks can be adjusted, and processing conditions suitable for the laser light irradiation device 1 to be used can be easily determined.

[0051] In the method for forming a rough surface by laser irradiation according to this embodiment configured as described above, even if the device configuration and processing parameters differ for each laser light irradiation device 1, processing conditions can be easily determined and processing can be performed.

[0052] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments and their modifications include, for example, those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are equivalent.

[0053] For example, in the method for roughening a surface by laser irradiation according to the above embodiment, the determining step determines whether the ratio (Sm / Rz) satisfies the above formula (1), but it is not limited to this formula (1). That is, the ratio (Sm / Rz) is not limited to 5 or less, and may be any predetermined value that is set in advance according to the laser light irradiation device used. [Explanation of symbols]

[0054] 1. Laser light irradiation device 2 Steel (test piece) 2a surface Rz Average surface roughness Sm Average spacing between rough surface peaks

Claims

1. A step of roughening a surface of a test piece made of steel by laser irradiation; a step of acquiring the surface roughness, the roughening depth, and the rough surface crest spacing of the roughened test piece; a step of determining whether Sm / Rz, which is the ratio of the average surface roughness Rz indicating the depth of the roughened surface at any 10 points on the roughened surface to the average spacing Sm between the roughened surface peaks, satisfies a predetermined value; a step of determining the types and contents of parameters, which are processing conditions for laser irradiation to be instructed to an operator, based on the determination result of the ratio; a step of outputting the determined instruction content; A method for forming a rough surface by laser irradiation, comprising:

2. 2. The method for forming a roughened surface by laser irradiation according to claim 1, wherein in the determining step, it is determined whether the ratio satisfies mathematical formula (1). [Equation 1]

3. In the determination result, If the formula (1) is satisfied, metal spraying is carried out based on the determined instruction content; 3. The method for forming a roughened surface by laser irradiation according to claim 2, wherein when the formula (1) is not satisfied and Sm / Rz is greater than 5, at least one of the average surface roughness Rz and the average spacing Sm between rough surface peaks is adjusted.

4. When adjusting the value of the average surface roughness Rz, 4. The method for forming a rough surface by laser irradiation according to claim 3, wherein at least one of the output and focal length of the laser irradiation is adjusted.

5. When adjusting the value of the average spacing Sm between rough surface peaks, 5. The method for forming a rough surface by laser irradiation according to claim 3, wherein at least one of the speed and width of the laser irradiation is adjusted.

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