Laser scraping process applied to metal surface

Abstract

The invention relates to the technical field of metal surface treatment, in particular to a laser scraping process applied to a metal surface, which is characterized in that a laser beam is emitted by a laser head of a laser system to act on the metal surface to be treated and is used for simultaneously cleaning and texturing the metal surface; the laser device for realizing the process is simple in structure, can be designed in a miniaturized manner, is better in applicability, and has more obvious advantages especially in complex application scenes such as bridge steel structures; before metal welding, welding while cleaning can be realized by using the laser scraping process, so that the construction efficiency is greatly improved, especially in bridge welding operation needing quick response and high precision; before the metal is painted, the laser scraping process is used, so that not only can anti-corrosion paint and a corrosion layer on the surface be thoroughly removed, but also uniform roughness can be formed on the surface, and an ideal base material strip is provided for coating.

Description

Technical Field

[0001] The present application belongs to the technical field of metal surface treatment, and in particular, relates to a laser scraping process applied to metal surfaces. Background Art

[0002] Metal surfaces usually need to be cleaned and pre-treated before painting or welding to ensure the quality of painting or welding. For example, there will be rust on the surface of steel components of infrastructure. Traditional rust removal methods mostly use physical or chemical methods. After cleaning, in order to enhance the adhesion of paint, roughening treatment is also required, such as the commonly used sandblasting roughening process. Traditional processes are not only inefficient, but also easy to damage the metal surface and pollute the environment.

[0003] Chinese patent 201910277672.X discloses a laser cleaning-texturing composite processing method, which divides the laser emitted by the laser into two beams, one for laser cleaning and the other for laser texturing, thereby realizing the composite processing of laser cleaning-texturing of materials; or uses two lasers to generate two laser beams respectively, one before and one after acting on the surface of the workpiece, with the cleaning laser in front and the texturing laser in the back, thereby realizing the composite processing of laser cleaning-texturing of materials. The technical solution of this invention patent (201910277672.X) has improved efficiency compared with traditional processes, but in essence it is still two processes spliced ​​together (laser cleaning, texturing) and operated separately to achieve the cleaning and texturing effect. The device structure to realize this process is complex and large in size, and is easily restricted by the use space and environment, and the production cost and use cost are high. Summary of the invention

[0004] The technical problem to be solved by the present invention is: to solve the deficiencies in the prior art, thereby providing a laser scraping process applied to metal surfaces, by which a laser beam acts on the metal surface to be processed, so as to simultaneously clean and roughen the metal surface, aiming to solve at least one of the above-mentioned technical problems.

[0005] The technical solution adopted by the present invention to solve its technical problem is: A laser scraping process applied to a metal surface, wherein a laser head of a laser system emits a laser beam to act on the metal surface to be processed, and is used for cleaning and texturing the metal surface at the same time; The laser system comprises an optical path system, which is used to guide and shape the laser beam and make the modulated laser beam act on the surface of the metal material; The power density of the laser beam modulated by the optical path system is 50-200 MW / cm 2 , the spot size of the laser beam is 50-200um; The laser system also includes a feedback system, which is used to collect workpiece surface temperature information, laser beam angle and position information, and feed the collected information back to the processing unit of the laser system to adjust the emission power, angle and position of the laser head.

[0006] Preferably, in a laser scraping process applied to a metal surface of the present invention, the optical path system comprises a collimating mirror, a first galvanometer mirror, a second galvanometer mirror and a lens group.

[0007] Preferably, in a laser scraping process applied to a metal surface of the present invention, the feedback system comprises a temperature management unit, and the temperature management unit comprises a temperature sensor for detecting temperature information of the surface of the metal workpiece.

[0008] Preferably, in the laser scraping process applied to metal surfaces of the present invention, the feedback system further comprises a gyroscope disposed on the laser head for detecting the angle and position information of the laser beam.

[0009] Preferably, a laser scraping process applied to a metal surface of the present invention also processes tail waste materials through a protection system, and the protection system includes a protective cover, an air blowing device and a dust suction device. The protective cover is used to enclose the working space, the air blowing device is used to blow away the peeling materials on the surface of the workpiece, and the dust suction device is used to absorb the peeling materials and waste gas in the protective cover.

[0010] Preferably, in a laser scraping process applied to metal surfaces of the present invention, before the laser scraping operation, the substrate to be retained and the dirt and coating to be removed are clearly identified based on the material properties, shape and size, surface quality of the steel structure workpiece to be scraped and the painting requirements after scraping, and the process parameters are determined based on the equipment and the properties of the laser beam.

[0011] Preferably, in a laser scraping process applied to a metal surface of the present invention, the parameter selection of the laser scraping process comprises the following steps: a) Establishing the energy density threshold range by scratching the material properties; b) Through the scratching experiment, the energy density parameters are adjusted and the damage threshold is tested; c) Find the relationship between damage threshold and surface topography and performance; When the energy density exceeds the damage threshold corresponding to the desired morphological characteristics, the energy density boundary of laser scratching is determined; d) According to the results of the scratching experiment, the process parameters of laser wavelength, power density, laser duty cycle, scratching efficiency and spot diameter are selected and optimized. The calculation formula of laser power density is: Pd=P / S; Where: Pd—laser power density, unit MW / cm 2 ; P—laser average power, unit MW; S—spot area, unit: cm 2 .

[0012] Preferably, in the laser scraping process for metal surface of the present invention, the process parameters during the scraping operation also include: the laser wavelength is 1.0-1.1 μm, the processing speed is 3-14 m / s, and the processing speed is 1.0-1.1 μm. 2 / h.

[0013] Preferably, in a laser scraping process applied to a metal surface of the present invention, the workpiece needs to be protected during and after the scraping operation, and the workpiece needs to be inspected after the scraping operation. The inspection items include the workpiece appearance, surface roughness, coating adhesion and surface hardness.

[0014] Preferably, in the laser scraping process for metal surface of the present invention, the metal to be processed includes steel and its alloys, aluminum and its alloys, titanium and its alloys.

[0015] The beneficial effects of the present invention are: (1) The laser scraping process of the present invention is to use a laser beam to act on the metal surface to be processed, and is used to clean and roughen the metal surface at the same time. The laser device for realizing this process has a simple structure and can be designed in a miniaturized manner, and has better applicability. In particular, in complex application scenarios such as bridge steel structures, the advantages of the laser scraping process of the present invention are more obvious; (2) Before metal welding, the laser scraping process can be used to achieve cleaning and welding, which greatly improves the construction efficiency, especially in bridge welding operations that require fast response and high precision; (3) Before painting the metal, the laser scraping process can not only completely remove the anti-corrosion paint and rust layer on the surface, but also form a uniform roughness on the surface, providing ideal substrate conditions for painting. Compared with traditional grinding or chemical cleaning methods, this laser scraping has the advantages of high efficiency and no pollution, which is more in line with modern environmental protection requirements; (4) This laser scraping process technology is pollution-free and can be precisely controlled, meeting the development requirements of more refined and green cleaning operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The technical solution of the present application is further described below in conjunction with the accompanying drawings and embodiments.

[0017] Figure 1 It is a schematic diagram of the process flow of an embodiment of the present application; Figure 2 is a schematic diagram of the structure of a laser system according to an embodiment of the present application; Figure 3 is a schematic diagram of the structure of a laser head according to an embodiment of the present application; Figure 4 This is a comparison diagram of the appearance of common steel after multiple groups of laser scratching experiments in the embodiment of the present application; Figure 5 It is an enlarged view of the surface and cross section of ordinary steel before and after laser scraping in an embodiment of the present application.

[0018] The reference numerals in the figure are: A collimating mirror 11 , a first galvanometer mirror 12 , a second galvanometer mirror 13 and a lens group 14 , a laser head 21 , a protective cover 22 , an air blowing knife 23 , a dust suction pipe 24 , and a laser beam 25 . DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0020] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0021] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0022] The technical solution of the present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0023] Embodiment: This embodiment provides a laser scraping process applied to metal surfaces. Figure 2 and Figure 3In the scraping process of this embodiment, a laser head 21 of the laser system emits a laser beam 25 to act on the metal surface to be processed, so as to clean and roughen the metal surface at the same time. The metal to be processed includes steel and its alloys, aluminum and its alloys, titanium and its alloys. In this embodiment, the metal to be processed is an ordinary steel plate (Q370qe steel plate).

[0024] Reference Figure 2 The laser system includes a laser for emitting laser light, an optical path system (scanning actuator), a control system and a cooling device.

[0025] The optical path system is used to guide and shape the laser beam and make the modulated laser beam act on the surface of the metal material. Specifically, refer to Figure 3 The optical path system includes a collimating mirror 11, a first galvanometer mirror 12, a second galvanometer mirror 13 and a lens group 14, wherein the lens group 14 includes at least one convex lens. In this embodiment, the lens group 14 includes 5 lenses arranged in parallel.

[0026] The laser emitted by the laser passes through the collimating mirror 11, is reflected by the first galvanometer 12 onto the second galvanometer 13, is reflected by the second galvanometer 13 onto the first convex lens, is initially focused by the first convex lens, and is projected onto the second convex lens. The laser is then focused again to reduce the spot size and is used as a laser scraping beam on the surface of the metal material to be processed.

[0027] Preferably, a laser scraping process applied to a metal surface in this embodiment is as follows: Figure 1 Before the laser scraping operation, the substrate that needs to be retained and the dirt and coating that need to be removed should be clearly identified based on the material properties, shape and size, surface quality of the steel structure workpiece to be scraped and the painting requirements after scraping, and the process parameters should be determined based on the equipment and the properties of the laser beam.

[0028] Preferably, in a laser scraping process applied to a metal surface in this embodiment, parameter selection of the laser scraping process includes the following steps: a) Establishing the energy density threshold range by scratching the material properties; b) Through the scratching experiment, the energy density parameters are adjusted and the damage threshold is tested; c) Find the relationship between damage threshold and surface topography and performance; When the energy density exceeds the damage threshold corresponding to the desired morphological characteristics, the energy density boundary of laser scratching is determined; d) According to the results of the scratching experiment, the process parameters of laser wavelength, power density, laser duty cycle, scratching efficiency and spot diameter are selected and optimized. The calculation formula of laser power density is: Pd=P / S; Where: Pd—laser power density, unit MW / cm 2 ; P—laser average power, unit MW; S—spot area, unit: cm 2 .

[0029] In the embodiment, multiple sets of experimental tests are also conducted for the selection of laser scraping process parameters for ordinary steel surfaces. Figure 4 , the experimental process and results are as follows: Experimental group 1: The laser wavelength in the process parameters is 1.0-1.1μm, the duty cycle is 80-100%, and the processing speed is 10-14m 2 / h, the power density of the laser beam after modulation by the optical path system is 0.6-25MW / cm 2 , the spot size of the laser beam is 50-200um. At this time, the rust cleaning effect on the steel surface is completed, that is, after laser surface scraping, it is observed with the naked eye or a magnifying glass. There is no residue on the surface of the workpiece to be removed (metal oxides and plating layers, coatings, pollutants, etc.) after laser scraping, but the roughening effect is not obvious. The surface roughness is measured by a probe-type profile measuring instrument or a three-dimensional optical profile measuring instrument. The roughness after roughening is approximately equal to 0. The bonding strength of the re-prepared coating after laser scraping is tested. The bonding strength between the substrate surface after laser scraping and the re-prepared coating is equal to or approximately equal to the bonding strength before the coating is removed, that is, the increased adhesion is approximately equal to 0MPa.

[0030] Experimental group 2: laser wavelength is 1.0-1.1μm, duty cycle is 50-80%, processing speed is 5-10m 2 / h, the power density of the laser beam after modulation by the optical path system is 25-60MW / cm 2 , the spot size of the laser beam is 50-200um. At this time, according to the test method of experimental group 1, the rust cleaning effect on the surface of ordinary steel is visually completed, and the roughening effect is obvious. The surface roughness test of the steel after roughening is 20-50μm, and the adhesion test is greater than 3MPa.

[0031] Experimental group 3: laser wavelength is 1.0-1.1μm, duty cycle is 10-50%, processing speed is 3-8m 2 / h, the power density of the laser beam after modulation by the optical path system is 50-76MW / cm 2 The spot size of the laser beam is 50-200um. According to the same test method of experimental groups one and two, the rust cleaning effect on the surface of ordinary steel is visually completed, and the roughening effect is very obvious. The surface roughness test of the steel after roughening is 50-100μm, and the adhesion test is greater than 5.9MPa.

[0032] The laser system in this embodiment also includes a feedback system, which is used to collect workpiece surface temperature information, laser beam angle and position information, and feed the collected information back to the processing unit of the laser system to adjust the emission power, angle and position of the laser head.

[0033] Specifically, the feedback system includes a temperature management unit, which includes a temperature sensor for detecting the surface temperature information of the metal workpiece and setting a temperature range according to the properties of the material. When the temperature of the surface of the metal workpiece exceeds the upper limit of the temperature range, during laser scraping, the processing unit of the laser system will reduce the power of the laser beam or increase the duty cycle, thereby reducing the temperature of the surface of the metal workpiece and preventing damage to the workpiece.

[0034] Preferably, in a laser scraping process applied to metal surfaces of the present embodiment, the feedback system also includes a gyroscope arranged on the laser head, which is used to detect the angle and position information of the laser beam, and set a laser beam rotation angle range according to the shape characteristics of the material and the working space. When the laser beam deflection angle exceeds the set range, the processing unit of the laser system will correct the rotation angle of the laser beam to ensure the operation quality and safety of laser scraping.

[0035] Preferably, in a laser scraping process applied to a metal surface in the present embodiment, the laser system also includes a protection system, the protection system includes a protective cover 22, an air blowing device and a dust suction device. In the present embodiment, the protective cover 22 is configured as a shell structure with a hollow bottom. When working, it covers the surface of the workpiece to close the working space. The laser head is arranged on the top of the protective cover 22, and the air blowing device is configured as an air blowing knife 23. The air blowing knife 23 blows out a high-speed air flow or an oxygen flow or a nitrogen flow to act on the scraped metal surface, so that the metal surface stripping material after the laser scraping operation is blown away from the working surface in time, thereby improving the scraping effect. The dust suction device adopts a vacuum cleaner connected to the protective cover 22 through a dust suction pipe 24, and the dust suction pipe mouth is arranged opposite to the air blowing knife 23, thereby increasing the discharge speed of the stripping material and exhaust gas.

[0036] A laser scraping process applied to a metal surface in this embodiment is described in detail in Figure 1 and Figure 5 , the specific steps are: Start the equipment to check whether the laser head, motion mechanism and laser operation are normal, adjust the red light mark to determine the surface treatment position, wear laser protective glasses, and ensure that there are no personnel, equipment or other dangerous goods on the laser transmission path. Perform a comprehensive inspection of the workpiece to be processed to confirm its surface condition, material type and structural integrity to ensure that it is suitable for laser scraping treatment.

[0037] Before the laser scraping work is carried out, it is carried out according to the process specification documents. According to the different surface roughness requirements of steel beams, supports and auxiliary steel structures before painting, the laser scraping process parameter range is determined using Appendix Table 1 combined with the existing experimental data of the steel substrate. The laser scraping process parameters are determined after verification.

[0038]

[0039] When performing laser scraping operations, the following processing requirements must be followed: The principle of step-by-step processing from the near end to the far end or from the upper end to the lower end of the workpiece should be followed; When processing thin-walled workpieces and mesh workpieces, the processing power should be controlled, and low power and multiple processing should be used to avoid deformation of the workpiece; When the oil stain on the workpiece is thick, the oil stain can be pre-treated, and the power can be adjusted during treatment to avoid generating open flames; Workpieces with rust or uneven coating thickness should be scraped with high power single treatment to form the surface structure in one go to avoid thermal damage accumulation and structural destruction; The smoke and exhaust gas generated by scraping should be removed and collected on the surface by side-blowing airflow and vacuum cleaning; Before painting, it is necessary to remove the attachments on the surface of the workpiece to avoid affecting the coating performance.

[0040] During laser scraping, the workpiece surface should be protected to prevent bumps; The workpiece after laser scraping should be stored in a dry place; the workpiece should be painted within 6 hours after laser scraping to prevent surface rust.

[0041] After laser scraping is completed, it needs to be tested and evaluated according to the quality standards in Table 2.

[0042]

[0043] Among them, for appearance inspection, observe with the naked eye or a magnifying glass. After laser scraping, there should be no obvious dirt or residual removal on the surface of the workpiece, and there should be no new cracks, scars, pits and other defects. When the user has cleanliness requirements for the workpiece, the cleanliness inspection is carried out according to the user's requirements, and the qualified cleanliness measurement result range is: Sa2-Sa3.

[0044] For surface roughness testing, the surface roughness of laser-scratched workpieces shall be evaluated according to the provisions of GB / T 1031. When laser scraping is the pre-painting process, the surface roughness test after treatment should be carried out according to the process requirements of the subsequent process. The surface roughness can be measured using a probe-type profilometer or a three-dimensional optical profilometer. The range of qualified surface roughness measurement results is: Ra20-Ra100.

[0045] For coating adhesion testing, when laser scraping is used to remove sprayed coatings and surface deposited layers, as well as other coating removals with special requirements for bonding strength, the bonding strength of the re-prepared coating after laser scraping should be tested. The bonding strength between the substrate surface after laser scraping and the re-prepared coating should not be lower than the bonding strength before coating removal, and should comply with the provisions in Table 2. The qualified adhesion result is: Level 0.

[0046] For hardness testing, the hardness after laser scratching and painting should meet the user's requirements, and the specimen, surface hardness measuring instrument and test steps should comply with the requirements of GB / T 6739. Hardness measurement result range: 1B-9B, HB, F, 1H-9H.

[0047] Based on the above ideal embodiments of this application, the relevant staff can make various changes and modifications without departing from the technical concept of this application through the above description. The technical scope of this application is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A laser scraping process applied to metal surfaces, characterized in that: The scraping process is to use a laser head of a laser system to emit a laser beam to act on the metal surface to be processed, so as to simultaneously clean and roughen the metal surface; The laser system comprises an optical path system, which is used to guide and shape the laser beam and make the modulated laser beam act on the surface of the metal material; The power density of the laser beam modulated by the optical path system is 50-200 MW / cm 2 , the spot size of the laser beam is 50-200um; The laser system also includes a feedback system, which is used to collect workpiece surface temperature information, laser beam angle and position information, and feed the collected information back to the processing unit of the laser system to adjust the emission power, angle and position of the laser head.

2. The laser scraping process for metal surface according to claim 1, characterized in that: The optical path system comprises a collimating mirror (11), a first galvanometer mirror (12), a second galvanometer mirror (13) and a lens group (14).

3. The laser scraping process for metal surface according to claim 2, characterized in that: The feedback system includes a temperature management unit, and the temperature management unit includes a temperature sensor for detecting surface temperature information of the metal workpiece.

4. The laser scraping process for metal surface according to claim 3, characterized in that: The feedback system also includes a gyroscope arranged on the laser head for detecting the angle and position information of the laser beam.

5. A laser scraping process for metal surface according to any one of claims 1 to 4, characterized in that: The laser scraping process also processes waste materials through a protection system, which includes a protective cover, an air blowing device and a dust suction device. The protective cover is used to enclose the working space, the air blowing device is used to blow away the peeling materials on the surface of the workpiece, and the dust suction device is used to absorb the peeling materials and waste gas in the protective cover.

6. The laser scraping process for metal surface according to claim 5, characterized in that: Before the laser scraping operation, the substrate that needs to be retained and the dirt and coating that need to be removed should be clearly identified based on the material properties, shape and size, surface quality of the steel structure workpiece to be scraped and the painting requirements after scraping, and the process parameters should be determined based on the equipment and the properties of the laser beam.

7. The laser scraping process for metal surface according to claim 6, characterized in that: The parameter selection of the laser scraping process includes the following steps: a) Establishing the energy density threshold range by scratching the material properties; b) Through the scratching experiment, the energy density parameters are adjusted and the damage threshold is tested; c) Find the relationship between damage threshold and surface topography and performance; When the energy density exceeds the damage threshold corresponding to the desired morphological characteristics, the energy density boundary of laser scratching is determined; d) According to the results of the scratching experiment, the process parameters of laser wavelength, power density, laser duty cycle, scratching efficiency and spot diameter are selected and optimized. The calculation formula of laser power density is: Pd=P / S; Where: Pd—laser power density, unit MW / cm 2 ; P—laser average power, unit MW; S—spot area, unit: cm 2 .

8. The laser scraping process for metal surface according to claim 7, characterized in that: During the scraping operation, the process parameters also include: laser wavelength is 1.0-1.1μm, processing speed is 3-14m 2 / h.

9. The laser scraping process for metal surface according to claim 7, characterized in that: The workpiece needs to be protected during and after the scraping operation. The workpiece also needs to be inspected after the scraping operation. The inspection items include workpiece appearance, surface roughness, coating adhesion and surface hardness.

10. The laser scraping process for metal surface according to claim 1, characterized in that: The metals to be processed include steel and its alloys, aluminum and its alloys, titanium and its alloys.

Images