A method of duplex cleaning of composite coatings

Abstract

The application provides a composite coating double cleaning method, comprising the following steps: adjusting the output parameters of laser and dry ice; spraying clean water; starting the dust collector; observing whether the area to be cleaned is covered with water; if yes, starting the laser output switch to perform laser ablation, if not, repeating the spraying of clean water until the area to be cleaned is covered with water; then starting the dry ice output switch to perform dry ice particle impact; after the cleaning is completed, first, the laser output switch is closed, then, after a delay of 1 second, the dry ice output switch is closed; and finally, the dust collector is closed. The application adopts the combination of two cleaning principles of laser and dry ice, simultaneous action, interaction and mutual complementation, namely, a double cleaning technology, which can efficiently remove the coating and effectively avoid the damage of the substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite coating cleaning methods, and particularly relates to a double cleaning method for composite coating. BACKGROUND

[0002] In order to reduce weight and improve carrying efficiency, resin-based composite materials are widely used in vehicles such as airplanes, ships and vehicles. In order to give them special protection functions (such as corrosion resistance, wear resistance, radiation resistance, etc.), a thick resin-based protective film is often coated on the surface. This protective film is also a resin-based composite material, and special functional solid particles or fibers are added to the resin matrix, which has high strength and hardness and large thickness. During maintenance, the existing coating needs to be completely removed and then re-coated. The current cleaning methods usually have the following several methods:

[0003] Mechanical polishing, mainly using sandpaper, sand cloth, sand wheel, or manual or machine, its main disadvantage is low efficiency;

[0004] Shot blasting cleaning, mainly by spraying high-speed sand, steel balls or special material particles, using the kinetic energy of these particles to impact and make the coating peel off and fall off. Its main disadvantages are: if the spraying speed is too low, the coating is not easy to remove; if the spraying speed is too high, it is easy to cause impact damage to the composite material substrate and cause delamination defects;

[0005] Plasma cleaning, mainly relying on high temperature, high frequency and high energy external conditions to generate low temperature plasma. The low temperature plasma is an electrically neutral, high energy and partially ionized gaseous substance. The energy of the low temperature plasma is about tens of electron volts, and the active particles such as ions, electrons, free radicals and ultraviolet radiation contained therein are easy to react with the contaminant molecules on the solid surface and make them separate, thereby playing a cleaning role. The disadvantage of the plasma method for cleaning the composite coating is that the energy of the low temperature plasma is much lower than that of the high-energy radiation, so this technology only involves the surface of the material, and the efficiency is relatively low;

[0006] High-pressure water jet cleaning, mainly using the kinetic energy of high-speed and high-pressure water flow to impact and even cut the coating, so that it peels off and falls off. Its main disadvantages are: first, the impact force is large, which is easy to cause delamination damage to the composite material substrate; second, the water flow enters the inside of the composite material or equipment, which has a certain pollution effect;

[0007] The cleaning mechanism of the laser cleaning to the coating mainly has the following three aspects: one is high temperature ablation, that is, the coating absorbs laser and quickly heats to melt, vaporize and oxidize; two is vibration, that is, when the absorption rate of the coating and the substrate to the laser is different and the thermal expansion coefficients are different, the irradiation of the laser will generate thermal stress between the coating and the substrate, so that the coating is peeled off; three is the effect of shock wave, which is divided into two cases, one case is that the laser induces plasma in the air on the surface of the coating to generate a shock wave, and the other case is that a layer of liquid (such as water or ethanol) is first covered on the surface of the coating, and the laser makes the liquid on the surface of the coating vaporize and expand to generate a shock wave. The shock waves generated in the two cases will have a peeling effect on the coating. The main disadvantage of this method for cleaning the composite coating is that the coating and the substrate are both resin-based composites, and the absorption rate and the thermal expansion coefficient of the laser are very close, so it is difficult to selectively act on the coating during cleaning, and the substrate is easily overheated and damaged by heat;

[0008] Dry ice cleaning, the principle of dry ice cleaning mainly has the following aspects: one is the kinetic energy impact of dry ice particles; two is the impact force generated by the rapid expansion of dry ice vaporization; three is the stress generated between the coating and the substrate by the rapid cooling of the coating by dry ice, and the brittleness of the coating. The disadvantage of using dry ice to clean the composite coating is that the kinetic energy impact of dry ice is the main mechanism, and a higher impact speed is required to be effective, which may cause impact damage to the substrate and generate delamination defects.

[0009] Engineering practice shows that the above cleaning and removal work has great difficulty, mainly in the following two aspects: one is the low efficiency of the removal work; two is that the substrate structure is easily damaged, so a safer and more efficient cleaning method is needed to realize the cleaning work of the composite coating. SUMMARY

[0010] Therefore, the present application provides a composite coating dual cleaning method, which combines the principles of laser and dry ice, simultaneously acts, interacts and compensates for each other, that is, a dual cleaning technology, which can efficiently remove the coating and effectively avoid damage to the substrate.

[0011] To solve the above technical problems, the present application provides a composite coating dual cleaning method, comprising the following steps:

[0012] Adjusting the output parameters of the laser and the dry ice, before the cleaning work is implemented, the output parameters of the laser and the dry ice are adjusted by using a test piece;

[0013] Spraying clean water, spraying clean water on the surface of the coating to be removed to ensure that the clean water is evenly attached, and the clean water is sprayed to the surface without flowing;

[0014] Turn on the dust collector, mainly used for cleaning the coating combustion or falling dust during cleaning;

[0015] Observe whether the area to be cleaned is covered with water, the purpose is to make the liquid vaporize and expand rapidly under the action of laser, form a shock wave, "bombard" the coating, and make it loose;

[0016] If the laser output switch is turned on, laser ablation is performed, and if not, the water spraying step needs to be repeated until the area to be cleaned is covered with water. The ablation principle in laser cleaning can make the coating heat up rapidly. In order to minimize the thermal impact on the substrate, the wavelength of the laser used for cleaning is controlled in the "ultraviolet" range, which can better control the heat effect within the coating and reduce the thermal impact on the substrate;

[0017] Turn on the dry ice output switch and perform dry ice particle impact. The kinetic energy of the dry ice particles used in dry ice cleaning can quickly remove the coating that has been softened at high temperature. Since the coating has been softened, a much lower impact speed can be used than ordinary dry ice cleaning, thereby avoiding impact damage to the substrate caused by dry ice particle impact. It should be noted that the laser beam should be in front and the dry ice beam should be behind. In addition, the area to be cleaned should be covered with water during cleaning. If the water layer is found to be dry, it should be resprayed. The surface moisture should meet the requirements before cleaning;

[0018] After cleaning, first turn off the laser output switch, and then turn off the dry ice output switch after a delay of 1 second. The purpose is to cool the cleaned area and avoid possible residual coating;

[0019] Turn off the dust collector. It should be noted that the dust collector should be turned off after the coating debris removed by cleaning is completely adsorbed;

[0020] The time interval between turning on the laser output switch and turning on the dry ice output switch is less than 0.5S to achieve mutual influence and make up for each other's shortcomings. Since the laser acts first, the coating has been loosened to some extent, so the mass and speed of the dry ice can be greatly reduced to prevent impact damage to the substrate. Since the dry ice is used for cooling afterwards, appropriately increasing the power of the laser will not cause thermal damage to the substrate. In this way, the removal efficiency can be greatly improved.

[0021] The amount of water sprayed should be appropriate to prevent the surface from flowing. The shock wave principle in laser cleaning is used to spray a layer of water on the surface to be cleaned before cleaning. The purpose is to make the liquid vaporize and expand rapidly under the action of laser, form a shock wave, "bombard" the coating, and make it loose.

[0022] Wherein, the closing of the dust collector is determined according to whether the removed coating is completely adsorbed as a reference.

[0023] The composite coating duplex cleaning device comprises a main machine integrated with a laser cleaning module and a dry ice cleaning module, a dry ice cleaning head for outputting laser and spraying dry ice for absorbing dust caused by coating combustion or peeling, and a dust collector.

[0024] The laser cleaning module comprises a laser, a laser controller and a water cooling device, wherein the laser is used to generate ultraviolet laser, the laser adopts fiber pulse type with a power of 200 W or more; the water cooling device is used to cool the laser, and forced circulation water cooling is adopted; the controller is used to adjust and control the laser and water cooling parameters, and the parameters of the laser and the parameters of the dry ice are independently adjusted, wherein the adjustment parameters of the laser include power, pulse width and pulse frequency, and the adjustable parameters of the dry ice device include dry ice particle size and jet speed.

[0025] The dry ice cleaning module is used to emit dry ice particles to clean the coating, and comprises an air compressor for compressing dry ice into granular dry ice, a dry ice container for containing dry ice, and a dry ice controller for spraying dry ice particles in the dry ice container.

[0026] The device further comprises a dry ice cleaning head for outputting laser and spraying dry ice, and a dust collector for absorbing dust caused by coating combustion or peeling; the cleaning head comprises a main pipeline connected with the laser through an optical fiber and connected with the dry ice container through a dry ice pipe, a telescopic pipe rotatably arranged on the main pipeline, and the telescopic pipe is rotatably arranged on the main pipeline through a universal knob.

[0027] The output of the laser and the dry ice is independently controlled by a switch. The angle of the dry ice spraying head and the distance from the laser output head can be adjusted, one is to ensure that the laser beam is in front and the dry ice beam is in back during work, two is to adjust the distance between the dry ice beam and the laser beam according to specific conditions, the distance of the two on the coating can be adjusted within the range of 0-10 mm, and three is to adjust the washing angle of the dry ice to the coating, and the adjustment range is 30-90°. In addition, the cleaning head also integrates an infrared temperature measurement function, which can measure the temperature of the cleaning area in real time, so as to monitor whether the substrate structure is damaged by heat in real time.

[0028] The dust collector is used to absorb dust caused by coating combustion or peeling, and prevent it from polluting the environment.

[0029] Compared with the prior art, the present application has at least one of the following beneficial technical effects:

[0030] 1. The method utilizes the advantages of both laser cleaning and dry ice cleaning and avoids their disadvantages. Before cleaning, a layer of water is sprayed on the surface to be cleaned, so that the liquid vaporizes and expands under the action of laser to form a shock wave, which "bombards" the coating and makes it loose. The ablation principle of laser cleaning is used to rapidly heat the coating. In order to minimize the thermal effect on the substrate, an ultraviolet laser is used.

[0031] 2. The dry ice particles impact the coating which has been softened by high temperature to remove it. Since the coating has been softened, the impact speed can be much lower than that of ordinary dry ice cleaning, thereby avoiding impact damage to the substrate. The low temperature of dry ice rapidly cools the cleaning area to avoid thermal damage to the substrate caused by laser ablation.

[0032] 3. The time interval between the "laser action" and "dry ice action" is less than 0.5 seconds to achieve mutual influence and to take advantage of each method and overcome its disadvantages. Since the laser acts first, the coating has been loosened to some extent, so the mass and speed of dry ice can be greatly reduced to prevent impact damage to the substrate. Since the dry ice is used to cool down, the power of the laser can be appropriately increased without causing thermal damage to the substrate, which can greatly improve the cleaning efficiency.

[0033] 4. The angle of the dry ice spray head and the distance from the laser output head can be adjusted. First, it ensures that the laser beam is in front and the dry ice beam is behind. Second, the distance between the dry ice beam and the laser beam can be adjusted according to the specific situation, and the distance of the two beams on the coating can be adjusted within the range of 0-10 mm. Third, the angle of the dry ice on the coating can be adjusted, and the adjustment range is 30-90°. In addition, the cleaning head also integrates an infrared temperature measurement function, which can measure the temperature of the cleaning area in real time to monitor whether the substrate structure is damaged by heat.

[0034] 5. A dust collector is used to absorb the dust generated by the burning or falling of the coating to prevent environmental pollution. BRIEF DESCRIPTION OF DRAWINGS

[0035] Fig. 1 The process flow chart of the composite coating dual cleaning method of the present application;

[0036] Fig. 2 The structure block diagram of the composite coating dual cleaning device of the present application.

[0037] BRIEF DESCRIPTION OF DRAWINGS: 100, mainframe; 110, laser cleaning module; 111, laser; 112, laser controller; 113, water cooling device; 120, dry ice cleaning module; 121, air compressor; 122, dry ice controller; 123, dry ice container; 200, cleaning head; 201, main pipe; 202, telescopic pipe; 203, universal knob; 300, dust collector. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the accompanying drawings of the embodiments of the present application to make a brief description of the technical solutions of the embodiments of the present application. Figs. 1-2 The technical solutions of the embodiments of the present application are described clearly and completely. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0039] As shown in the figure: the embodiment provides a composite coating duplex cleaning method, comprising the following steps: Figs. 1-2 Adjusting the output parameters of the laser and the dry ice, before the implementation of the cleaning work, adjusting the output parameters of the laser and the dry ice by using a test piece;

[0040] Spraying clean water, spraying clean water on the surface to be cleaned of the coating, ensuring that the clean water is evenly attached, and the clean water sprayed to the surface does not flow;

[0041] Turning on the dust collector 300, which is mainly used for collecting the dust generated by the burning or falling of the coating during the cleaning process;

[0042] Observing whether the area to be cleaned is covered with water layer, the purpose is to make the liquid rapidly vaporize and expand under the action of the laser, form a shock wave, and "bombard" the coating, so as to loosen it;

[0043] If the laser output switch is turned on, laser ablation is performed, if not, the clean water spraying step needs to be performed again until the area to be cleaned is covered with water layer, using the ablation principle in the laser cleaning, the coating can be rapidly heated in order to minimize the thermal effect on the substrate, using ultraviolet laser, the wavelength of the laser used for cleaning is controlled in the "ultraviolet" range, which can better control the thermal effect within the coating and reduce the thermal effect on the substrate;

[0044]

[0045] ​The dry ice output switch is opened, dry ice particle impact is carried out, and the kinetic energy of the dry ice particles used for dry ice cleaning is used to impact the coating which has been softened at high temperature, so that the coating is quickly removed. Since the coating has been softened, a much lower impact speed than ordinary dry ice cleaning can be used at this time, thereby avoiding impact damage to the substrate caused by dry ice particle impact. It should be noted that the laser beam should be in front and the dry ice beam should be behind. In addition, the area to be cleaned should be covered with water during cleaning. If the water layer is found to have dried out, it should be resprayed. The surface water should meet the requirements before cleaning is carried out.

[0046] After cleaning is completed, the laser output switch is first closed, and the dry ice output switch is closed after a delay of 1 second. The purpose of this is to cool the cleaned area and avoid possible residual coating.

[0047] The dust collector 300 is turned off. It should be noted that the dust collector 300 should be turned off after the coating debris removed by cleaning is completely adsorbed.

[0048] The time interval between opening the laser output switch and opening the dry ice output switch is less than 0.5S to achieve mutual influence and make up for each other's shortcomings. Since the laser acts first, the coating has been loosened to some extent, so the mass and speed of the dry ice can be greatly reduced to prevent impact damage to the substrate. Since the dry ice is used for cooling afterwards, appropriately increasing the power of the laser will not cause thermal damage to the substrate. In this way, the removal efficiency can be greatly improved.

[0049] The amount of water sprayed should be appropriate so that the surface to be cleaned does not flow. The principle of shock wave action in laser cleaning is used. Before cleaning, a layer of water is sprayed on the surface to be cleaned. The purpose is to make the liquid vaporize and expand rapidly under the action of the laser, forming a shock wave to "bombard" the coating and loosen it.

[0050] The dust collector 300 is turned off according to whether the coating removed is completely adsorbed.

[0051] A composite coating dual cleaning device, comprising a main machine 100 integrated with a laser cleaning module 110 and a dry ice cleaning module 120, a dry ice cleaning head 200 for outputting laser and for absorbing dust generated by burning or falling off of the coating, and a dust collector 300.

[0052] The laser cleaning module 110 comprises a laser 111, a laser controller 112 and a water cooling device 113, wherein the laser 111 is used to generate ultraviolet laser, the laser 111 adopts a fiber pulse type, and the power is above 200 W; the water cooling device 113 is used to cool the laser 111, and forced circulation water cooling is adopted; the controller is used to adjust and control the laser and the water cooling parameters, and the parameters of the laser and the parameters of the dry ice are independently adjusted, wherein the adjustment parameters of the laser 111 include power, pulse width and pulse frequency, and the adjustable parameters of the dry ice device include dry ice particle size and jet speed.

[0053] The dry ice cleaning module 120 is used to emit dry ice particle cleaning coating, and comprises an air compressor 121 used to compress dry ice into granular dry ice, a dry ice container 123 used to store dry ice and a dry ice controller 122 used to spray dry ice particles in the dry ice container 123.

[0054] Further, a dust collector 300 used to absorb dust caused by burning or peeling of the coating is further included; the cleaning head 200 comprises a main pipeline 201 connected with the laser 111 through an optical fiber and connected with the dry ice container 123 through a dry ice pipe, a telescopic pipe 202 is rotationally arranged on the main pipeline 201, and the telescopic pipe 202 is rotationally arranged on the main pipeline 201 through a universal knob 203.

[0055] The output of the laser and the dry ice is independently controlled by a switch. The angle of the dry ice spraying head and the distance from the laser output head can be adjusted, so that the laser beam is in front and the dry ice beam is behind during work, the distance between the dry ice beam and the laser beam can be adjusted according to specific conditions, the distance of the two on the coating can be adjusted in the range of 0-10 mm, and the washing angle of the dry ice to the coating can be adjusted in the range of 30-90°. In addition, the infrared temperature measurement function is integrated in the cleaning head 200, so that the temperature of the cleaning area can be measured in real time, so as to monitor whether the substrate structure is damaged by heat in real time.

[0056] The dust collector 300 is used to absorb dust caused by burning or peeling of the coating, so as to prevent pollution to the environment.

[0057] The cleaning method and the cleaning principle of the present application are as follows:

[0058] The cleaning principle is as follows:

[0059] (1) The shock wave action principle in laser cleaning is used, and before cleaning, a layer of clean water is sprayed on the surface to be cleaned, so that the liquid is rapidly vaporized and expanded under the action of laser to form a shock wave to "bombard" the coating and make it loose.

[0060] (2) The ablation principle in laser cleaning is used to rapidly heat the coating. In order to minimize the thermal influence on the substrate, ultraviolet laser is used.

[0061] (3) The kinetic energy of dry ice particles is used to remove the softened coating. Since the coating has been softened, the impact speed of dry ice particles can be much lower than that of normal dry ice cleaning, thus avoiding impact damage to the substrate.

[0062] (4) The low-temperature rapid cooling effect of dry ice is used to rapidly reduce the temperature of the cleaning area to avoid thermal damage to the substrate caused by laser ablation.

[0063] (5) The time interval between "laser action" and "dry ice action" is less than 0.5 seconds to achieve mutual influence, thus taking advantage of each method and overcoming its shortcomings. Since the laser acts first, the coating has been loosened to some extent, so the mass and speed of dry ice can be greatly reduced to prevent impact damage to the substrate; since the dry ice is used for cooling afterwards, the power of the laser can be appropriately increased without causing thermal damage to the substrate, thus greatly improving the removal efficiency.

[0064] (6) The laser wavelength used in the cleaning process should be controlled in the "ultraviolet" range to better control the thermal effect within the coating and reduce the thermal effect on the substrate.

[0065] The following process steps are used to remove the coating on the surface of a composite material using the "double" method:

[0066] (1) Before the cleaning work is implemented, the output parameters of the laser and dry ice are adjusted using test pieces.

[0067] (2) Before the cleaning is implemented, water is sprayed on the surface of the coating to be removed to ensure uniform adhesion, and the amount of water sprayed is determined by the principle that the surface does not flow.

[0068] (3) Turn on the dust collector 300.

[0069] (4) Turn on the laser output switch, delay for 0.5 seconds, and then turn on the dry ice output switch. When moving the cleaning head 200, ensure that the laser beam is in front and the dry ice beam is behind. In addition, ensure that the area to be cleaned is covered with water. If the water layer is found to have dried up, re-spray and implement cleaning after the surface water meets the requirements.

[0070] (5) After cleaning is completed, first turn off the laser output, delay for 1 second, then turn off the dry ice output, and finally delay to turn off the dust collector 300 according to the situation.

[0071] The specific operation steps are as follows:

[0072] Adjust the output parameters of the laser and dry ice. Before the cleaning work is implemented, the output parameters of the laser and dry ice are adjusted using test pieces.

[0073] Spray clean water, spray clean water on the surface to be cleaned of coating, ensure that clean water is evenly attached, and the amount of spraying is based on the principle that the surface does not flow;

[0074] Turn on the dust collector 300, which is mainly used to burn or remove the dust of the coating washed down during the cleaning process;

[0075] Observe whether the area to be cleaned is covered with a water layer, the purpose of which is to make the liquid rapidly vaporize, expand, form a shock wave, and "bombard" the coating under the action of laser, so as to loosen it;

[0076] If the laser output switch is turned on, laser ablation is performed, and if not, the clean water spraying step needs to be performed again until the area to be cleaned is covered with a water layer. By using the ablation principle in cleaning, the coating can be rapidly heated. In order to minimize the thermal effect on the substrate, the wavelength of the laser used for cleaning is controlled in the "ultraviolet" range, which can better control the thermal effect within the coating and reduce the thermal effect on the substrate;

[0077] Turn on the dry ice output switch and perform dry ice particle impact. The kinetic energy of the dry ice particles used in dry ice cleaning impacts the coating that has been softened at high temperature and rapidly removes it. Since the coating has been softened, a much lower impact speed than ordinary dry ice cleaning can be used at this time to avoid impact damage to the substrate caused by dry ice particle impact. It should be noted that the laser beam should be in front and the dry ice beam should be behind. In addition, the area to be cleaned should be covered with water during cleaning. If it is found that the water layer has dried up, it should be sprayed again. The surface moisture should meet the requirements before cleaning is performed;

[0078] After cleaning is completed, first turn off the laser output switch, and then turn off the dry ice output switch after a delay of 1 second. The purpose of this is to cool the cleaned part and avoid possible residual coating;

[0079] Turn off the dust collector 300. It should be noted here that the dust collector 300 should be turned off after the coating debris washed down is completely adsorbed;

[0080] In addition, it should be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection" and "connection" should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0081] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles described in the present application, can also be made several improvements and refinements, these improvements and refinements should also be considered the scope of protection of the present application.

Claims

1. A method for dual-stage cleaning of composite material coatings, comprising the following steps: S1: Turn on the laser output switch to perform ultraviolet laser ablation; S2: Then turn on the dry ice output switch to perform dry ice particle impact; S3: After cleaning, first turn off the laser output switch, and then turn off the dry ice output switch after a 1-second delay; The time interval between S1 and S2 is less than 0.5S; Turn on the vacuum cleaner (300) before step S1; Spray water before turning on the vacuum cleaner (300), ensuring the water does not drip onto the surface to be cleaned.

2. The method for dual cleaning of composite material coatings as described in claim 1, characterized in that: Adjust the output parameters of the laser and dry ice before spraying water.

3. The method for dual cleaning of composite material coatings as described in claim 2, characterized in that: After turning on the vacuum cleaner (300) and before turning on the laser output switch, observe whether there is a water layer covering the area to be cleaned. If there is, turn on the laser output switch. If not, spray clean water again until the surface to be cleaned does not drip. Then turn on the laser output switch.

4. The method for dual cleaning of composite material coatings as described in claim 3, characterized in that: After turning off the dry ice output switch, turn off the vacuum cleaner (300).

5. The method for dual cleaning of composite material coatings as described in claim 4, characterized in that: The decision to turn off the vacuum cleaner (300) is based on whether the removed coating has been completely absorbed. When the removed coating has been completely absorbed, the vacuum cleaner (300) is turned off. When the removed coating has not been completely absorbed, the vacuum cleaner (300) is turned on until the removed coating has been completely absorbed, and then the vacuum cleaner (300) is turned off.

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