Laser irradiation method for roughening surfaces

Abstract

Even if the device configuration and processing parameters differ for each laser irradiation device, processing conditions can be easily determined and processing can be performed. [Solution] The present invention provides a laser irradiation method for forming a rough surface, comprising the steps of: roughening a test piece made of steel by laser irradiation; obtaining the surface roughness, roughening depth, and rough surface peak spacing of the roughened test piece; determining whether the ratio Sm / Rz, which is the ratio of the average surface roughness Rz, which indicates the roughening depth at any 10 roughened points, to the average rough surface peak spacing Sm, satisfies a predetermined value; determining the type and content of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, based on the ratio determination result; and outputting the determined instruction content. In the determination step, the present invention provides a laser irradiation method for forming a rough surface, which determines whether the ratio Sm / Rz ≤ 5.

Description

Technical Field

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

Background Art

[0002] Conventionally, for example, in order to deal with the deterioration due to aging of galvanized steel materials used in steel towers for power transmission equipment and the like, rust prevention painting is generally performed as a measure for extending the life. In particular, when the deterioration progresses significantly and the galvanization has disappeared, the steel material has to be replaced. Therefore, in order to avoid replacing the steel material, a metal sprayed film having a rust prevention ability equal to or higher than that of hot-dip galvanization is formed on site. In such a metal spraying method, in order to adhere the metal film to the sprayed base material, roughening of the surface of the steel material is performed. For example, there is known a method of performing rust prevention spraying in which a blasting material (abrasive) is sprayed at high speed to remove rust, corrosion products, etc., then a surface roughness is formed, and then a metal melted by an arc welder is sprayed to regenerate the rust prevention ability.

[0003] As a blasting treatment for projecting a blasting material for roughening the surface of a steel material, a spraying blasting method is known (for example, see Patent Document 1). In the spraying blasting method, a hard abrasive is directly used for the sprayed base material, and the blasting abrasive is projected with strong pressure to form a roughening in order to firmly adhere the sprayed film to the sprayed base material. As a result, large irregularities and scratches are formed on the sprayed base material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, with the conventional blast treatment described above, the abrasive material generated by the process scatters into the surrounding area, requiring thorough protection of the work site, which increases costs. In particular, when the application involves work at heights such as steel towers, as mentioned above, setting up protective equipment requires considerable time and effort. Furthermore, the generated abrasive material also needs to be collected.

[0006] Incidentally, a method is known in which a laser irradiation device is used to irradiate the surface of steel with a laser to remove only the rust on the surface of the steel. Although it is conceivable to roughen the surface of steel by irradiating it with a laser using such a laser irradiation device, a high-power laser irradiation device is required because it creates deep irregularities on the steel material that is the substrate to be thermal sprayed. In other words, when roughening the surface using laser irradiation in the surface roughening process before anti-corrosion spraying, the equipment configuration and processing parameters differ for each laser irradiation device used. This makes it time-consuming to pre-determine processing conditions for all laser irradiation devices, and it is difficult to perform irradiation treatment with appropriate processing conditions. There was room for improvement in this respect.

[0007] This invention has been made in consideration of these circumstances, and its purpose is to provide a laser irradiation method for forming rough surfaces that allows for easy determination of processing conditions and processing, even when the device configuration and processing parameters differ for each laser irradiation device. [Means for solving the problem]

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

[0009] According to the laser irradiation surface roughening method of the present invention, by irradiating a test piece with a laser using a laser irradiation device to perform surface roughening, the average surface roughness Rz and the average spacing between rough surface peaks Sm are obtained. It is then determined whether the ratio of this average surface roughness Rz to the average spacing between rough surface peaks Sm (Sm / Rz) satisfies a predetermined value, and based on this determination result, the type and content of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, can be determined. By following this procedure, processing conditions suitable for each laser irradiation device can be easily determined, so that even if the device configuration and processing parameters differ for each laser irradiation device, the processing conditions for forming the optimal rough surface necessary for anti-corrosion spraying can be set in advance for all laser irradiation devices. Furthermore, the laser irradiation surface roughening method according to the present invention allows surface roughening to be performed by laser irradiation, eliminating the need for time-consuming tasks such as installing protective equipment to prevent the scattering of abrasive material, as in conventional blast treatment methods, and collecting the abrasive material. This reduces costs and improves work efficiency.

[0010] (2) Aspect 2 of the present invention may be characterized in that, in the laser irradiation method for forming a rough surface according to aspect 1, the determination step involves determining whether the ratio satisfies formula (1).

[0011]

number

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

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

[0014] In this case, if formula (1) is not satisfied in the determination process, the type and content of the parameters, which are the processing conditions for laser irradiation instructed to the operator, can be determined specifically and reliably 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) Aspect 4 of the present invention is a method for forming a rough surface by laser irradiation according to aspect 2, in which, 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, by adjusting at least one of the laser irradiation output and focal length, the average surface roughness Rz value can be adjusted, making it easy to determine processing conditions suitable for the laser irradiation device being used.

[0017] (5) In aspect 5 of the present invention, in the laser irradiation method for forming a rough surface according to 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 laser irradiation speed and width.

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

Advantages of the Invention

[0019] According to the rough surface formation method by laser irradiation according to the present invention, even when the device configuration and processing parameters differ for each laser light irradiation apparatus, the processing conditions can be easily determined and processing can be performed.

Brief Description of the Drawings

[0020] [Figure 1] It is a perspective view showing a rough surface formation method by laser irradiation according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view of a steel material in a state where rust preventive coating is applied by the rough surface formation method. [Figure 3] (a) to (d) are diagrams showing the construction procedure up to rust preventive coating including the rough surface formation method by laser irradiation. [Figure 4] It is a diagram showing a flowchart of the rough surface formation method by laser irradiation. [Figure 5] It is a diagram for explaining the average interval between rough surface peaks. [Figure 6] It is a diagram for explaining the average surface roughness.

Modes for Carrying Out the Invention

[0021] Hereinafter, embodiments of the rough surface formation method 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 visible.

[0022] The rough surface formation method by laser irradiation in this embodiment is adopted for the construction of rust preventive coating, which is generally used as a life extension measure against the deterioration of galvanized steel materials used in iron towers such as power transmission facilities over time.

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

[0024] The metal spray coating layer 21 is formed by spraying molten metal using an arc welding machine. The sealing layer 22 is provided so as to cover the surface of the metal spray coating layer 21, and is treated to protect the surface of the metal spray coating layer 21 and to fill minute voids on the surface. The rust-preventive coating layer 23 (primer layer 23A and topcoat layer 23B) has been treated to enhance rust prevention and weather resistance.

[0025] Figures 3(a) to 3(d) show the construction procedure, including the method of roughening the surface by laser irradiation, up to the application of rust-preventive coating. As shown in Figure 3(a), first, a surface roughening process is performed using a laser irradiation device 1 to roughen the entire surface 2a of the existing steel material 2 to be coated with rust-preventive paint. The laser irradiation device 1 is moved so that the laser beam 1a is irradiated onto the entire surface 2a of the steel material 2. The reference numeral 2b in Figure 3(a) indicates the roughened surface formed by laser irradiation. The specific method of roughening the surface by laser irradiation will be described later.

[0026] Next, as shown in Figure 3(b), a rust-preventive spraying process is performed to form a metal spray coating layer 21 by applying rust-preventive spraying to the rough surface 2b of the steel material 2. In the rust-preventive spraying process, the metal spray coating layer 21 is formed by spraying molten metal 3a, obtained from an arc welding machine 3, onto the rough surface 2b of the steel material 2. Here, the electric arc spraying used in the anti-corrosion spraying process is performed at low voltage and low temperature, and a metal coating of, for example, aluminum (Al)-magnesium (Mg) alloy (Al: 95%, Mg: 5%) is used. The standard spray coating thickness is, for example, 150 μm. In addition to the electric arc spraying described above, metal spraying can also be performed using other spraying equipment and methods such as gas flame spraying and plasma wire spraying in the anti-corrosion spraying process.

[0027] Subsequently, as shown in Figure 3(c), a sealing treatment step is performed to provide a sealing treatment layer 22 that covers the surface of the metal spray coating layer 21. In the sealing treatment step, the sealing treatment layer 22 is formed by applying a sealing treatment material to protect the surface of the metal spray coating layer 21 and fill minute voids on the surface.

[0028] Next, as shown in Figure 3(d), a rust-preventive coating process is performed to apply a rust-preventive coating layer 23 so as to cover the surface of the sealing treatment layer 22. In the rust-preventive coating process, the rust-preventive coating layer 23 is formed by applying a rust-preventive treatment material to enhance rust prevention and weather resistance.

[0029] Next, we will specifically explain the method for roughening surfaces using laser irradiation. Figure 4 shows a flowchart of the laser irradiation roughening method. The roughening method is a method for carrying out the roughening treatment process described above. First, in step S1, the test piece made of steel is subjected to rough, uneven surface processing by laser irradiation using the laser light irradiation device 1 (see Figure 3(a)).

[0030] The laser irradiation in this case may be either a pulsed wave or a continuous wave. A high-power laser irradiation device 1 is used, and pulsed waves make it easier to create deep irregularities with less power, and shorter irradiation distances also make it easier to create deep irregularities. Examples of laser irradiation devices 1 used for roughening include laser cleaning devices, laser cleaners, laser scrapers, and laser blasters. For example, when the laser light irradiation output is 100W to 500W, a pulsed wave is preferred. For high-power laser light irradiation outputs of 500W to 3000W or more, both pulsed and continuous wave waveforms are possible, but a continuous wave allows for faster and easier surface roughening of irregularities.

[0031] Next, the surface roughness, roughening depth, and the resulting surface ridge spacing of the roughened specimen are obtained (Step S2). These surface roughness values ​​are measured using a surface roughness meter (surface roughness measuring instrument). For example, a "compact surface roughness measuring instrument" (SURFTEST SJ-310 series, manufactured by Mitutoyo Corporation) with a measurement range of 16 mm on the X axis and 360 μm [-200 to +160] on the Z1 axis (surface roughness), can be used as the roughness meter.

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

[0033]

number

[0034] Here, the average spacing Sm between rough surface peaks is calculated by summing the lengths of the average lines (Sm1, Sm2, ..., Smi, Smn) corresponding to one peak and one adjacent valley in the reference length, as shown in Figure 5. The arithmetic mean of these many irregularities is called Sm(μm) (see formula (2)). However, there are minimum height and minimum length requirements. If the height (depth) is 10% or less of the maximum value, or the length is 1% or less of the calculation interval, these are considered noise and are treated as part of the preceding and succeeding peaks and valleys.

[0035]

number

[0036] The average surface roughness Rz is the 10-point average surface roughness. 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) for each reference length, and the average of the absolute values ​​of the lowest valley bottoms Yv1 to the fifth valley bottom Yv5.

[0037]

number

[0038] In equation (1), if the value of Sm / Rz is greater than 5, the adhesion strength between the metal spray coating layers is very high, and cohesive failure of the spray layers does not occur. Therefore, in the vertical tensile strength test of the spray coating, interfacial failure will always occur first between the substrate to be sprayed and the spray coating, resulting in delamination. In other words, if the value of Sm / Rz is 5 or less, an ideal uneven surface condition for the metal spray coating can be created on the substrate to be sprayed, the adhesion strength of the metal spray coating is reliably improved, and stable adhesion strength of the coating can be ensured.

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

[0040] If the result of step S3 satisfies formula (1) (Sm / Rz ≤ 5, step S3: Yes), the process proceeds to step S4, and metal spraying is performed based on the determined instructions. If formula (1) is not satisfied and Sm / Rz is greater than 5 (Sm / Rz > 5, step S3: No), proceed to step S5 and adjust at least one of the average surface roughness Rz and the average spacing between rough surface peaks Sm.

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

[0042] In step S5, when adjusting the value of the average spacing Sm between rough surfaces (step S7), at least one of the laser irradiation speed and width is adjusted. For example, to increase the value of the average spacing Sm between rough surfaces, the laser irradiation speed is increased or the laser irradiation width is widened. On the other hand, to decrease the value of the average spacing Sm between rough surfaces, the laser irradiation speed is decreased or the laser irradiation width is narrowed.

[0043] Then, after adjusting the Sm and Rz values ​​in steps S6 and S7, the process returns to step S1.

[0044] Furthermore, the laser irradiation method for roughening the surface described above can be realized by using a computer calculation program. Specifically, the calculation program for the roughening method performs the following steps: step S1, which involves roughening a steel specimen with an uneven surface by laser irradiation using the laser light irradiation device 1; step S2, which involves obtaining the surface roughness, roughening depth, and rough surface peak spacing of the roughened specimen; step S3, which involves determining whether the average surface roughness Rz and average peak spacing Sm, which indicate the roughening depth at any 10 roughened points, satisfy formula (1); and step S4, which involves determining the type and content of the parameters that are the processing conditions for laser irradiation to be instructed to the operator, based on the determination result from formula (1), and outputting the determined instructions. In this case, the system includes a computer (CPU or MPU) (not shown) that stores and executes the calculation program for the laser irradiation surface roughening method described above.

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

[0046] According to this embodiment, by performing surface roughening on a test piece using a laser irradiation device 1 to be used in advance, the average surface roughness Rz and the average spacing between rough surface peaks Sm are obtained. It is then determined whether the ratio of this average surface roughness Rz to the average spacing between rough surface peaks Sm (Sm / Rz) satisfies a predetermined value, and based on this determination result, the type and content of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, can be determined. By following this procedure, it is possible to easily determine processing conditions suitable for each laser irradiation device 1 used. Therefore, even if the device configuration and processing parameters differ for each laser irradiation device 1, the processing conditions for forming the optimal rough surface necessary for anti-corrosion spraying can be set in advance for all laser irradiation devices 1. Furthermore, in this embodiment, surface roughening can be performed by laser irradiation, eliminating the need for time-consuming tasks such as installing protective equipment to prevent the scattering of abrasive material, as in conventional blasting methods, and collecting the abrasive material. This reduces costs and improves work efficiency.

[0047] Furthermore, in this embodiment, the determination step involves determining whether the ratio Sm / Rz satisfies formula (1). Therefore, by determining that the ratio of the average surface roughness Rz to the average spacing between rough surface peaks Sm (Sm / Rz) is 5 or less, the type and content of the parameters that constitute the laser irradiation processing conditions to be instructed to the operator can be determined specifically and reliably.

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

[0049] Furthermore, in the laser irradiation method for roughening surfaces according to this embodiment, when adjusting the average surface roughness Rz value, at least one of the laser irradiation output and focal length is adjusted. Therefore, by adjusting at least one of the laser irradiation output and focal length, the average surface roughness Rz value can be adjusted, and processing conditions suitable for the laser irradiation device 1 being used can be easily determined.

[0050] Furthermore, in the laser irradiation method for roughening surfaces according to this embodiment, when adjusting the value of the average spacing Sm between rough surface peaks, at least one of the laser irradiation speed and width is adjusted. Therefore, by adjusting at least one of the laser irradiation speed and width, the average spacing Sm between rough surface peaks can be adjusted, making it easy to determine processing conditions suitable for the laser irradiation device 1 being used.

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

[0052] Although 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. 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. Embodiments and their modifications include, for example, those that can be easily imagined by those skilled in the art, those that are substantially the same, and those that are equivalent.

[0053] For example, in the laser irradiation surface roughening method of the above embodiment, the determination step involves determining whether the ratio (Sm / Rz) satisfies the above formula (1), but it is not limited to formula (1). In other words, it is not limited to the ratio (Sm / Rz) being 5 or less, but any predetermined value that corresponds to the laser irradiation device used is acceptable. [Explanation of Symbols]

[0054] 1. Laser beam irradiation device 2. Steel material (test piece) 2a surface Rz average surface roughness Sm Average interval between rough surfaces and mountains

Claims

1. A process of roughening the surface of a test piece made of steel by laser irradiation, A process to obtain the surface roughness, roughening depth, and roughening ridge spacing of the roughened test piece, A step of determining whether the ratio Sm / Rz, which is the ratio of the average surface roughness Rz, which indicates the roughening depth at any 10 points that have been roughened, to the average spacing between roughened surface peaks Sm, satisfies a predetermined value, A step of determining the type and content of the parameters, which are the processing conditions for laser irradiation to be instructed to the operator, based on the result of the ratio determination, The process of outputting the determined instructions, A method for roughening a surface by laser irradiation, comprising the characteristics of a laser irradiation.

2. The method for forming a rough surface by laser irradiation according to claim 1, wherein in the step of determining whether the ratio satisfies formula (1). [Math 1]

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

4. When adjusting the value of the average surface roughness Rz, The method for roughening a 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 distance Sm between rough surfaces and mountains, The method for roughening a surface by laser irradiation according to claim 3 or 4, wherein at least one of the speed and width of the laser irradiation is adjusted.

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