A dual-source composite laser cleaning method and apparatus

Abstract

This invention relates to a dual-source composite laser cleaning method and apparatus, comprising: determining the area to be cleaned; setting the incident angle, reciprocating oscillation angle, and cleaning parameters of a pulsed laser head and a continuous laser head incident on the layer to be cleaned; based on the single pulse spot formed by the pulsed laser, scanning and overlapping the single pulse spot into a pulse spot array under the action of a scanning galvanometer, the pulse spot array forming a pulsed laser scanning area under the reciprocating oscillation of the pulsed laser head; based on the continuous laser spot formed by the continuous laser, scanning and overlapping the continuous laser spot into a continuous laser scanning matrix under the action of a scanning galvanometer, the continuous laser scanning matrix forming a continuous laser scanning area under the reciprocating oscillation of the continuous laser head; and performing composite laser cleaning along the scanning path according to the cleaning parameters, wherein, during composite laser cleaning, the pulsed laser scanning area and the continuous laser scanning area at least partially overlap to avoid ablation of the workpiece substrate.

Description

Technical Field

[0001] This invention pertains to laser cleaning technology, utilizing a composite light source of continuous laser and pulsed laser to clean the surface coating of metal workpieces. Specifically, it relates to a dual-light source composite laser cleaning method and apparatus. Background Technology

[0002] Laser cleaning technology, as a highly efficient and environmentally friendly industrial cleaning technique, does not damage the properties of the surface being cleaned, does not produce toxic gases or noise, and is harmless to humans and the environment. It boasts advantages such as high efficiency, flexibility, and ease of automation, and is gradually being promoted and applied in the industrial field. Currently, laser cleaning methods on the market are mainly divided into two categories based on their working mode.

[0003] The first type is continuous laser cleaning, which uses a continuous laser as the light source and a continuous laser cleaning head for laser cleaning. The advantages of this type of cleaning equipment are its lower cost and higher cleaning efficiency. The disadvantage is that the large heat input of the continuous laser can easily cause micro-melting of the substrate, thus damaging it. Continuous laser cleaning is currently mainly used in civilian applications such as rust removal and dirt removal where there are no strict requirements regarding substrate damage.

[0004] The second type is pulsed light cleaning, which uses a pulsed laser and a pulsed light cleaning head for laser cleaning. The advantage of this type of equipment is that the pulsed laser has low heat input and is less likely to damage the substrate. The disadvantage is that the pulsed laser uses a multi-point overlapping scanning method for cleaning, which can easily lead to gaps and repeated overlapping in the overlapping areas, resulting in low cleaning efficiency. This inefficiency is particularly pronounced when cleaning difficult-to-clean materials such as titanium alloy platings and coatings. For example, when cleaning a 1mm thick absorbing coating on a titanium alloy substrate using a 500W nanosecond pulsed cleaning device, it is necessary to scan the same location of the absorbing coating 5 to 15 times to completely remove the coating, resulting in extremely low efficiency. Summary of the Invention

[0005] This invention addresses the above-mentioned problems by proposing a dual-source composite laser cleaning method and apparatus, which aims to prevent overheating caused by continuous laser irradiation of the same location and effectively avoid ablation of the workpiece substrate.

[0006] To achieve the above objectives, the present invention provides a dual-source composite laser cleaning method, comprising the following steps:

[0007] Identify the area to be cleaned;

[0008] Based on the area to be cleaned, the incident angle, reciprocating swing angle, and cleaning parameters of the pulsed laser head and the continuous laser head are set for the layer to be cleaned.

[0009] Based on the single pulse spot formed by the pulsed laser, the single pulse spot is scanned and overlapped into a pulse spot array under the action of the scanning galvanometer. The pulse spot array forms a pulsed laser scanning area under the reciprocating oscillation of the pulsed laser head. Based on the continuous laser spot formed by the continuous laser, the continuous laser spot is scanned and overlapped into a continuous laser scanning matrix under the action of the scanning galvanometer. The continuous laser scanning matrix forms a continuous laser scanning area under the reciprocating oscillation of the continuous laser head.

[0010] Composite laser cleaning is performed along the scanning path according to the cleaning parameters, wherein, during composite laser cleaning, the pulsed laser scanning area and the continuous laser scanning area at least partially overlap.

[0011] Furthermore, the oscillation direction of the pulsed laser head is opposite to that of the continuous laser head.

[0012] Furthermore, the cleaning parameters include: wavelength, pulse width, frequency, rated power, scanning speed, and reciprocating oscillation frequency.

[0013] Furthermore, the reciprocating oscillation angles of the pulsed laser head and the continuous laser head are both within the range of ±15 degrees; the scanning beams emitted by the pulsed laser head and the continuous laser head form an angle of 45° to 75° with the layer to be cleaned.

[0014] Furthermore, the length of the pulsed light spot array is equal to the length of the continuous laser scanning matrix.

[0015] Furthermore, the length of the pulsed laser scanning area is equal to the length of the continuous laser scanning area.

[0016] Furthermore, before determining the cleaning area, the process also includes pre-treating the coating on the surface of the workpiece to be cleaned to remove adhesive foreign matter from the coating surface.

[0017] Furthermore, during the composite laser cleaning process, a monitoring device is activated to detect the cleaning process, and laser cleaning is repeated for any items that fail the detection.

[0018] To achieve the above objectives, the present invention provides a dual-source composite laser cleaning device, the device comprising a pulsed laser cleaning head, a continuous laser cleaning head, two rotating connecting plates, a connecting base, and two rotating motors; the two rotating connecting plates are respectively disposed on the connecting base, the rotating motors are disposed on the connecting base, the rotating motors are connected to the rotating connecting plates, and are used to drive the rotating connecting plates to swing; the pulsed laser cleaning head and the continuous laser cleaning head are respectively disposed on the two rotating connecting plates.

[0019] Furthermore, the device also includes a monitoring device, which is fixedly connected to the connecting base and located between the pulsed laser cleaning head and the continuous laser cleaning head, for detecting the cleaning process.

[0020] The technical solution of this invention has the following advantages: It utilizes both continuous and pulsed laser light sources for laser cleaning, employing a combined effect. The high peak power of the pulsed laser penetrates the coating at multiple points, creating a micropore-like destructive effect. Simultaneously, the continuous laser causes the substrate to absorb energy, generating a vapor cloud that creates thermal expansion pressure between the metal and the substrate, reducing their bonding force. Finally, the vibrational shock waves generated by the continuous and pulsed lasers cause the coating to peel off, thus achieving rapid laser cleaning. This method combines the advantages of both continuous and pulsed lasers, significantly improving laser cleaning efficiency and preventing overheating caused by continuous irradiation of the same location by two laser beams, effectively avoiding ablation of the workpiece substrate. Attached Figure Description

[0021] Figure 1 This is a flowchart of a dual-source composite laser cleaning method disclosed in an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of a dual-source composite laser cleaning structure disclosed in an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of a rectangular pulsed light spot array and a pulsed scanning area disclosed in an embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of a continuous laser scanning matrix and scanning area disclosed in an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the structure of a composite light source spot scanning coating disclosed in an embodiment of the present invention.

[0026] Figure 6 This is a flowchart of a composite light source coating laser cleaning process disclosed in an embodiment of the present invention.

[0027] In the figure: 1. Pulsed laser cleaning head; 2. Continuous laser cleaning head; 3. Rotating connecting plate; 4. Base; 5. Substrate to be cleaned; 6. Layer to be cleaned; 7. Monitoring device; 8. Rotary motor; 1-1. Pulsed laser scanning beam; 1-2. Pulsed spot array; 2-1. Continuous laser scanning beam; 2-2. Continuous laser scanning matrix. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0031] like Figure 2 As shown, the laser cleaning apparatus for implementing the laser cleaning method of the present invention comprises: a pulsed laser cleaning head 1 for emitting a pulsed laser scanning beam 1-1; a continuous laser cleaning head 2 for emitting a continuous laser scanning beam 2-1; two rotating connecting plates 3 for mounting the pulsed laser cleaning head 1 and the continuous laser cleaning head 2 respectively; a connecting base 4 for mounting the two rotating connecting plates 3 at both ends; a worktable for placing the substrate 5 to be cleaned; a monitoring device 7 for monitoring the coating cleaning thickness; and a rotary motor 8 for driving the pulsed laser cleaning head 1 and the continuous laser cleaning head 2 to rotate on the rotating connecting plates 3.

[0032] In this example, various laser heads supplied and sold by laser manufacturers can be used as pulsed laser cleaning head 1 and continuous laser cleaning head 2.

[0033] In this example, the rotating connecting plate 3 is made of brass 62. It is used to adjust and fix the laser incident angles α and β of the pulsed laser scanning beam 1-1 and the continuous laser scanning beam 2-1, and is mounted on the connecting base 4 to form a whole. During laser cleaning, it moves as a whole along the cleaning direction of the pulsed laser cleaning head 1 and the continuous laser cleaning head 2.

[0034] In this example, the connecting base 4 is made of brass 62 and serves as a mounting base. The pulsed laser cleaning head 1 and the continuous laser cleaning head 2 are connected by the connecting base 4 to form a whole, and the whole moves along the cleaning direction during laser cleaning.

[0035] In this example, monitoring device 7 uses a CCD infrared camera, along with post-processing software, to monitor the coating cleaning thickness.

[0036] As a rotary motor 8, it is used to drive the pulsed laser cleaning head 1 and the continuous laser cleaning head 2 to reciprocate.

[0037] Next, the laser cleaning method using a laser cleaning device will be explained, such as... Figure 1 As shown. The laser cleaning method includes the following steps:

[0038] Step S100: Determine the area to be cleaned;

[0039] Step S200: Based on the area to be cleaned, set the incident angle, reciprocating oscillation angle, and cleaning parameters of the pulsed laser head and the continuous laser head into the layer to be cleaned;

[0040] Step S300: Based on the single pulse spot formed by the pulsed laser, the single pulse spot is scanned and overlapped into a pulse spot array under the action of the scanning galvanometer. The pulse spot array forms a pulsed laser scanning area under the reciprocating oscillation of the pulsed laser head. Based on the continuous laser spot formed by the continuous laser, the continuous laser spot is scanned and overlapped into a continuous laser scanning matrix under the action of the scanning galvanometer. The continuous laser scanning matrix forms a continuous laser scanning area under the reciprocating oscillation of the continuous laser head.

[0041] Step S400: Perform composite laser cleaning along the scanning path according to the cleaning parameters, wherein, during composite laser cleaning, the pulsed laser scanning area and the continuous laser scanning area at least partially overlap.

[0042] In the above embodiment, the pulsed laser cleaning head 1 serves as the source of the pulsed laser, and its main function is to emit the pulsed laser cleaning source. Its preferred parameters are a wavelength of 1064 nm, a pulse width of 130 ns, a frequency of 0–50 kHz, a rated power of 500 W, and a scanning speed of 1000 mm–10000 mm. The pulsed scanning beam 1-1 emitted by the pulsed laser cleaning head 1 forms an angle β with the layer 6 to be cleaned. During the composite laser cleaning operation, the pulsed laser cleaning head 1 reciprocates under the drive of the rotary motor 8, with the angle β oscillating within a range of ±15 degrees, and the oscillation frequency being 3–50 times per second.

[0043] The pulsed scanning beam 1-1 is emitted from the pulsed laser cleaning head 1, and the pulsed scanning beam 1-1 forms an angle β with the layer 6 to be cleaned. The pulsed scanning beam 1-1 passes through the scanning galvanometer inside the pulsed laser cleaning head 1, and the individual pulse spots are quickly overlapped to form a pulse spot array 1-2 with a length of D1 and a width of H.

[0044] A single pulse spot is rapidly scanned and overlapped by a scanning galvanometer to form a pulse spot pattern with a length of D1 and a width of H, as shown below. Figure 3 As shown. At the same time, the rectangular pulsed spot array 1-2 forms a pulsed laser scanning area with a width of D1 and a length of L1 under the reciprocating oscillation of the pulsed laser cleaning head 1.

[0045] like Figure 4 As shown, the continuous laser cleaning head 2 serves as the source of continuous laser light, its main function being to emit continuous laser cleaning light. The preferred parameters are a wavelength of 1064 nm, a rated power of 1000 W, and a scanning speed of 1000 mm to 10000 mm. The continuous laser scanning beam 2-1 emitted by the continuous laser cleaning head 2 forms an angle α with the layer 6 to be cleaned. During the composite laser cleaning operation, the continuous laser cleaning head 2 reciprocates under the drive of the rotary motor 8, with the angle α oscillating within a range of ±15 degrees, and the oscillation frequency being 3 to 50 times per second.

[0046] A continuous laser scanning beam 2-1 is emitted from the continuous laser cleaning head 2, and the continuous laser scanning beam 2-1 forms an angle α with the coating 6 to be cleaned. The continuous laser scanning beam 2-1 passes through a scanning galvanometer inside the continuous laser cleaning head 2, rapidly scanning the continuous laser spot into a continuous laser scanning matrix 2-2 with a length D2 and a width K, as shown below. Figure 4 As shown.

[0047] A scanning galvanometer rapidly scans and overlaps continuous laser spots to form a scanning pattern with length D and width K. Simultaneously, the continuous laser scanning matrix 2-2, under the reciprocating oscillation of the continuous laser cleaning head 2, forms a continuous laser scanning area with width D2 and length L2.

[0048] During laser cleaning, the pulsed laser scanning area formed by the reciprocating motion of the pulsed spot array 1-2 and the continuous laser scanning area formed by the reciprocating motion of the continuous laser scanning matrix 2-2 at least partially overlap. When they completely overlap, D1 = D2 and L1 = L2. At this time, the high peak power of the pulsed spot array 1-2 causes multi-point deep damage to the coating, forming a small hole damage effect with a certain depth. At the same time, the continuous laser scanning matrix 2-2 causes the adhering material to absorb energy and generate a vapor cloud, forming thermal expansion pressure between the metal material and the adhering material, reducing the bonding force between them. Finally, the vibration shock wave generated by the continuous laser scanning matrix 2-2 and the pulsed spot array 1-2 causes the coating to peel off, thereby achieving rapid laser cleaning and forming an effect of 1+1>2.

[0049] It should be noted that, compared with the composite laser technology in the prior art, this embodiment uses dual-beam laser oscillation, which can prevent the laser from continuously irradiating the same position and causing overheating, and can effectively avoid the ablation of the workpiece substrate.

[0050] For continuous laser cleaning and pulsed laser cleaning of thick coatings (≥1mm) on metal substrates, the composite light source coating laser cleaning process is as follows: Figure 6 As shown, it includes:

[0051] Step S1: Pre-treat the coating on the surface of the workpiece to be cleaned. The pre-treatment method includes cleaning the adhesive on the coating surface with alcohol or acetone to remove the adhesive foreign matter on the coating surface.

[0052] Step S2: Adjust the initial angle of laser incident angle α to 60 degrees, the initial angle of β to 60 degrees, the swing angle of α and β to ±3 degrees, and the swing frequency of α and β to 20 times.

[0053] Step S3: Set the continuous laser parameters as follows: power 500W, D1=D2 = 80mm, K = 6mm, scanning speed 8000mm / s; pulsed laser parameters: power 400W, D = 80mm, H = 3mm, L1=L2 = 10mm, scanning speed 6000mm / s, frequency 45kHz. Overall travel cleaning speed 2400mm / s.

[0054] Step S4: Perform laser cleaning according to the set parameters.

[0055] Step S5: During the cleaning process, turn on the monitoring device 7 to detect the cleaning process.

[0056] Step S6: If the inspection is passed, the laser cleaning process is complete. If the inspection fails, the laser cleaning process is repeated.

[0057] The following section will provide a detailed explanation of a dual-source composite laser cleaning method using specific examples.

[0058] according to Figure 2 A dual-source composite laser cleaning device was constructed. It consists of one pulsed laser with a rated power of 500W, a wavelength of 1064nm, a pulse width of 130ns, a frequency of 0–50kHz, and a scanning speed of 1000mm–10000mm. It also includes one continuous laser with a wavelength of 1064nm, a rated power of 1000W, and a scanning speed of 1000mm–10000mm. The rotating connecting plate 3 and the connecting base 4 are made of 62 brass.

[0059] The objects to be cleaned are: a TC4 titanium alloy substrate (i.e., substrate 5 to be cleaned) with a thickness of 3mm and a NiCrW coating with a thickness of 1mm (i.e., coating 6 to be cleaned).

[0060] Cleaning tests were conducted according to Tables 1 and 2 respectively.

[0061] Table 1

[0062]

[0063]

[0064] Table 2

[0065]

[0066] After testing, cleaning was performed according to Tables 1 and 2 respectively, and the coating thickness removal on the titanium alloy substrate surface was measured after cleaning. The tests showed that cleaning according to Table 1, repeated twice, removed 1 mm of coating. Cleaning according to Table 2, repeated three times, removed 1 mm of coating.

[0067] Compared to simple continuous laser cleaning, the thickness removed by repeating the process 6 times under the same parameters reaches 1mm. The cleaning efficiency is increased by about 300% by using a composite laser source, and the substrate is undamaged after surface cleaning.

[0068] Compared to simple pulsed laser cleaning, the thickness removed by repeating the process 11 times under the same parameters reaches 1mm, which is about 500% more efficient, and the substrate is not damaged after surface cleaning.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual-source composite laser cleaning method, characterized in that, The following steps are involved: Identify the area to be cleaned; Based on the area to be cleaned, the incident angle, reciprocating swing angle, and cleaning parameters of the pulsed laser head and the continuous laser head are set for the layer to be cleaned. Based on the single pulse spot formed by the pulsed laser, the single pulse spot is scanned and overlapped into a pulse spot array under the action of the scanning galvanometer. The pulse spot array forms a pulsed laser scanning area under the reciprocating swing of the pulsed laser head. Based on the continuous laser spot formed by the continuous laser, the continuous laser spot is scanned and overlapped into a continuous laser scanning matrix under the action of the scanning galvanometer. The continuous laser scanning matrix forms a continuous laser scanning area under the reciprocating swing of the continuous laser head. Composite laser cleaning is performed along the scanning path according to the cleaning parameters. The high peak power of the pulsed laser array causes multi-point deep damage to the coating, forming a small hole damage effect with a certain depth. At the same time, the continuous laser scanning matrix causes the adhering material to absorb energy and generate a vapor cloud, forming thermal expansion pressure between the metal material and the adhering material, reducing the bonding force between the two. Finally, the vibration shock wave generated by the continuous laser scanning matrix and the pulsed laser array causes the coating to peel off. In the composite laser cleaning, the pulsed laser scanning area and the continuous laser scanning area overlap at least partially.

2. The dual-source composite laser cleaning method as described in claim 1, characterized in that, The pulsed laser head swings in the opposite direction to the continuous laser head.

3. The dual-source composite laser cleaning method as described in claim 1, characterized in that, The cleaning parameters include: wavelength, pulse width, frequency, rated power, scanning speed, and reciprocating oscillation frequency.

4. The dual-source composite laser cleaning method as described in claim 1, characterized in that, The reciprocating oscillation angles of the pulsed laser head and the continuous laser head are both within the range of ±15 degrees; the scanning beams emitted by the pulsed laser head and the continuous laser head form an angle of 45° to 75° with the layer to be cleaned.

5. The dual-source composite laser cleaning method as described in claim 1, characterized in that, The length of the pulsed spot array is equal to the length of the continuous laser scanning matrix.

6. The dual-source composite laser cleaning method as described in claim 5, characterized in that, The length of the pulsed laser scanning area is equal to the length of the continuous laser scanning area.

7. The dual-source composite laser cleaning method as described in claim 1, characterized in that, Before determining the cleaning area, the process also includes pre-treating the coating on the surface of the workpiece to be cleaned to remove any sticky foreign matter from the coating surface.

8. The dual-source composite laser cleaning method as described in claim 1, characterized in that, During the composite laser cleaning process, a monitoring device is activated to detect the cleaning process. If the process fails the test, the laser cleaning is repeated.

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