Coating method

Abstract

The invention discloses a coating method. The method comprises the steps that S101, the surface of a workpiece is coated with decorative paint to obtain a decorative coating, the range of the decorative coating is larger than that of a decorative area of the surface of the workpiece, and the surface of the workpiece is one of metal, a high polymer material, a composite material, an electrophoretic coating, a primer coating, a floating coat coating, a colored paint coating or a varnish coating; s102, the surface of the workpiece is coated with main color paint to obtain a main color coating, and the main color coating covers the whole surface of the workpiece; s103, the workpiece is heated and dried; s104, laser cleaning equipment is used for removing the main color coating on the decoration area and part of the decoration coating on the decoration area; s105, the surface of the workpiece is coated with varnish to obtain a varnish coating, and the varnish coating covers the whole surface of the workpiece; and S106, the workpiece is heated and dried. According to the invention, the problems of low automation degree and use of a large amount of consumables in the coating of decorative coatings with colors different from those of the vehicle body in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of coating, in particular to a coating method. Background Art

[0002] During the painting process of automobile bodies, there are demands for appearances with multiple colors, such as decorative strips, special patterns, etc. in certain areas of the body outer panel, which require decorative coating effects with colors different from the main color of the body.

[0003] At present, one method to achieve this decorative coating is to mask the non-decorative area with materials such as tape and masking film to form a mask after the primary color coating and clear coating are applied to the entire workpiece and baked. Then, the decorative coating is applied to the decorative area, the masking material is removed, and the clear coating is applied to the entire workpiece and baked. In this method, the masking process requires manual operation, the operation time is long, the degree of automation is low, a large amount of consumables are used, and the entire vehicle needs to be coated with clear coating twice. There are disadvantages such as low production cycle, unstable quality and high cost.

[0004] Another method of achieving this decorative coating is to use a device similar to a print head to apply the decorative coating without overspray on the decorative area after applying the main color coating to the entire workpiece, and then low-temperature bake the decorative area, and then apply the clear coating to the entire workpiece and bake it. This method requires the redevelopment of the equipment structure, and the maintenance method is complicated. The coating effect is poor on the high curvature areas of the workpiece surface, such as A-pillars and ridges, and the current conventional coatings containing aluminum powder or pearlescent powder with special appearance effects cannot be used. It is necessary to use specially developed plain color coatings that do not contain aluminum powder or pearlescent powder. There are disadvantages such as high investment and operating costs, limited decorative coating areas, limited types of decorative coatings, and limited decorative effects.

[0005] Another possible method of achieving such a decorative coating is to attach a film with a decorative color and shape to the main color coating or the clear coating after the entire workpiece is coated and baked with the main color coating or the clear coating, and then the entire workpiece is coated with the clear coating and baked. In this method, the film attachment process requires manual operation, the operation time is long, the degree of automation is low, and it can only be operated on a flat area, which has the disadvantages of low production cycle, unstable quality, and limited decorative coating area. Summary of the invention

[0006] The purpose of the present invention is to provide a coating method to solve the problems in the related art of low automation and use of a large amount of consumables in coating decorative coatings of different colors from the vehicle body.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The coating method comprises: step S101, applying decorative paint to the surface of a workpiece to obtain a decorative coating, wherein the range of the decorative coating is larger than the range of a decorative area on the surface of the workpiece, wherein the surface of the workpiece is one of metal, polymer material, composite material, electrophoretic coating, primer coating, intermediate coating, color paint coating or varnish coating; step S102, applying primary color paint to the surface of the workpiece to obtain a primary color coating, wherein the primary color coating covers the entire surface of the workpiece; step S103, heating and drying the workpiece; step S104, removing the primary color coating on the decorative area and part of the decorative coating on the decorative area using a laser cleaning device; step S105, applying varnish to the surface of the workpiece to obtain a varnish coating, wherein the varnish coating covers the entire surface of the workpiece; step S106, heating and drying the workpiece.

[0009] It is further configured as follows: using atomizing coating equipment to apply decorative paint, primary color paint and varnish, the atomizing coating equipment includes a rotary cup atomizer and an air atomizing spray gun; the multi-axis robotic arm guides the atomizing coating equipment to move along a preset trajectory, atomizes the paint into paint mist, and transfers it to the workpiece surface.

[0010] It is further configured that: heating and drying the workpiece includes: hot air heating or infrared heating of the workpiece.

[0011] It is further configured as follows: the drying equipment is one of a fixed drying furnace, a fixed infrared baking lamp, and an infrared baking lamp driven by a multi-axis robotic arm.

[0012] The further settings are: for water-based paint and 3C1B mid-coat, the drying temperature is set to 60℃~80℃; for the composite coating after spraying low-temperature varnish, the drying temperature is set to 70℃~90℃; for 3C2B mid-coat and the composite coating after spraying high-temperature varnish, the drying temperature is set to 130℃~150℃.

[0013] It is further configured that: the drying range is the wet film coating area or the entire workpiece, wherein the wet film coating area is the area sprayed with decorative paint, main color paint and varnish.

[0014] It is further configured as follows: the multi-axis robotic arm guides the laser cleaning equipment to move along a preset trajectory, and the laser cleaning equipment controls the laser beam to move within a set width range perpendicular to the moving direction, wherein the coating removal thickness of the laser cleaning equipment is greater than the maximum film thickness of the main color coating in the decorative area.

[0015] It is further configured as follows: adjusting the parameters of the laser cleaning equipment to control the coating removal thickness, wherein the parameters include power and moving speed, and the coating removal thickness is greater than the maximum film thickness of the main color coating in the decorative area.

[0016] It is further configured as follows: when the width of the decoration area perpendicular to the movement direction of the laser cleaning equipment is greater than the maximum width of the laser beam movement, the decoration area is divided into at least two areas in the width direction, and then the laser cleaning equipment is used for cleaning, wherein one area corresponds to one cleaning path.

[0017] It is further configured as follows: an overlap width is set in the boundary area between two adjacent cleaning paths, and when cleaning is performed, the removal thickness is linearly reduced to zero within the overlap width.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are: through a fully automated process, from the coating of decorative paint to the main color paint and then to the varnish, as well as the subsequent laser cleaning and re-drying, the entire process does not require manual intervention, significantly improving the production cycle and ensuring the efficiency and stability under large-scale production. This process does not require the development of special coating equipment or materials, reducing the initial equipment investment cost. Laser cleaning technology only consumes electricity, and does not require chemical solvents or a large amount of water resources required for traditional cleaning. It is both environmentally friendly and economical, further reducing operating costs. By first applying a larger decorative coating on the surface of the workpiece, and then using a laser to accurately remove the excess coating in the non-decorated area, not only the precise definition of the decorative area is achieved, but also the effect pigments such as aluminum powder and pearlescent powder can be flexibly used to enhance the decorative effect and meet the diverse and personalized aesthetic needs. This process is suitable for workpiece surfaces of various materials, including metals, polymer materials, composite materials and different coating stages (such as electrophoretic coatings, primers to varnish layers), showing a wide range of material compatibility and process flexibility, and is suitable for a variety of industrial coating scenarios.

[0019] In summary, this technical solution not only greatly improves production efficiency and quality stability, but also maximizes economic benefits through resource conservation and cost control, while ensuring the diversity and high-end nature of decorative effects. It is an important technological innovation in the field of modern industrial coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a flow chart of the coating method of the present invention;

[0022] Figure 2A Front view of the decorative coating being applied;

[0023] Figure 2BTop view of the decorative coating being applied;

[0024] Figure 3A Front view of the main color coating;

[0025] Figure 3B Top view of the main color coating;

[0026] Figure 4A This is the front view of laser removal;

[0027] Figure 4B A top view of laser removal;

[0028] Figure 5A This is the main view after laser removal;

[0029] Figure 5B This is a top view after laser removal;

[0030] Fig. 6A This is the front view of the varnish application;

[0031] Figure 6B This is a top view of the application of clear coat;

[0032] Fig. 7A A front view of laser cleaning for a first cleaning path width and a second cleaning path width;

[0033] Figure 7B A top view of laser cleaning for a first cleaning path width and a second cleaning path width;

[0034] Fig. 8A A schematic diagram of the coating removal effect of the first cleaning path and the coating removal of the second cleaning path;

[0035] Figure 8B A front view of the coating removal effect of the first cleaning path and the coating removal effect of the second cleaning path;

[0036] Fig. 9A is a schematic diagram of the cleaning effect when the distance between two adjacent cleaning paths is smaller than the theoretical distance;

[0037] Fig. 9B This is a front view of the cleaning effect when the distance between two adjacent cleaning paths is smaller than the theoretical distance;

[0038] Fig. 10A is a schematic diagram of the cleaning effect when the distance between two adjacent cleaning paths is greater than the theoretical distance;

[0039] Fig. 10B This is a front view of the cleaning effect when the distance between two adjacent cleaning paths is greater than the theoretical distance;

[0040] Fig.11AA front view showing the overlap width between the first cleaning path width and the second cleaning path width;

[0041] Fig. 11B A top view of the overlap width between the first cleaning path width and the second cleaning path width;

[0042] Fig. 12A A schematic diagram showing that the coating removal effect of the first cleaning path and the coating removal effect of the second cleaning path gradually decrease to zero within the overlap width;

[0043] Fig. 12B A front view showing that the coating removal effect of the first cleaning path and the coating removal effect of the second cleaning path gradually decrease to zero within the overlap width;

[0044] Fig.13A is a schematic diagram of the cleaning effect when the distance between two adjacent cleaning paths is smaller than the theoretical distance;

[0045] Fig. 13B This is a front view of the cleaning effect when the distance between two adjacent cleaning paths is smaller than the theoretical distance;

[0046] Fig.14A is a schematic diagram of the cleaning effect when the distance between two adjacent cleaning paths is greater than the theoretical distance;

[0047] Fig. 14B This is a front view of the cleaning effect when the distance between two adjacent cleaning paths is greater than the theoretical distance;

[0048] Fig.15 The schematic diagram of the device principle of the print head;

[0049] Fig.16 is a schematic diagram of the second coating process steps;

[0050] Fig.17 Schematic diagram of the third coating process step.

[0051] Figure numerals: 201, workpiece; 202, decorative coating; 203, primary color coating; 204, varnish coating; 206, decorative area; 207, coating removal thickness; 301, atomizing coating equipment; 302, paint mist; 401, laser cleaning equipment; 402, laser beam; 403, first cleaning path width; 404, second cleaning path width; 405, overlap width; 406, first cleaning path coating removal effect; 407, second cleaning path coating removal effect; 408, combined coating removal effect; 409, repeat positioning error; 501, print head; 502, micropore; 503, paint jet. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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 present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0054] In the description of the present invention, 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 the present invention can be understood according to specific circumstances.

[0055] Example

[0056] Reference Figure 1 , is a coating method disclosed in the present invention, which includes: step S101, applying decorative paint to the surface of a workpiece 201 to obtain a decorative coating 202, the range of the decorative coating 202 is larger than the range of a decorative area 206 on the surface of the workpiece 201, wherein the surface of the workpiece 201 is one of metal, polymer material, composite material, electrophoretic coating, primer coating, intermediate coating, color paint coating or varnish coating 204; step S102, applying primary color paint to the surface of the workpiece 201 to obtain a primary color coating 203, the primary color coating 203 covers the entire surface of the workpiece 201; step S103, heating and drying the workpiece 201; step S104, using a laser cleaning device 401 to remove the primary color coating 203 on the decorative area 206 and part of the decorative coating 202 on the decorative area 206; step S105, applying varnish to the surface of the workpiece 201 to obtain a varnish coating 204, the varnish coating 204 covers the entire surface of the workpiece 201; step S106, heating and drying the workpiece 201.

[0057] Specifically, this solution solves the following technical problems: solving the problems of long operation time and unstable quality caused by manual operation; solving the problem of high operating costs caused by additional consumables such as masking films or tapes, and the need to specially develop coatings; solving the problem of limited decorative effects caused by only being able to use plain paints that do not contain aluminum powder or pearlescent powder.

[0058] It is further configured as follows: using an atomizing coating device 301 to apply decorative paint, primary color paint and varnish, the atomizing coating device 301 includes a rotary cup atomizer and an air atomizing spray gun; the multi-axis robotic arm guides the atomizing coating device 301 to move along a preset trajectory, atomizes the paint into paint mist 302, and transfers it to the surface of the workpiece 201.

[0059] The coating uses atomizing coating equipment 301, which includes a rotary cup atomizer and an air atomizing spray gun, which are commonly used equipment in the industry. Figure 2A , Figure 3A as well as Fig. 6A A rotary cup atomizer is shown as an example. The atomizing coating device 301 is guided by a multi-axis robot (not shown in the figure). The atomizing coating device 301 is guided by a multi-axis robot to move along a preset trajectory, atomizing the coating material used in the coating into a paint mist 302 and transferring it to the surface of the workpiece 201.

[0060] The range of the decorative coating 202 should be completely covered and larger than the graphic range of the decorative area 206. Figure 2B As shown, the dotted line in the figure is used to indicate that the decorative layer finally presents the pattern of the decorative area 206. Since the film thickness within the range of the paint mist 302 atomized by the currently commonly used atomizing coating equipment 301 is uneven, a uniform coating can only be obtained by overlapping spraying at a certain distance. The film thickness of the outer periphery of the spraying area where overlapping spraying is not possible is gradually reduced. Therefore, the spraying range of the decorative coating 202 must be larger than the graphic range of the decorative area 206 to ensure that the decorative area 206 obtains a uniform film thickness. The range of the decorative coating 202 coating may also cover the entire surface of the workpiece 201.

[0061] Decorative paint and primary color paint are both commonly used materials. Decorative paint and primary color paint belong to the same type of materials, only the color or appearance effect is different. It can be a solid color paint, or the appearance effect can be enhanced by adding aluminum powder or pearl powder.

[0062] The coating range of the primary color coating 203 covers the entire surface of the workpiece 201. Figure 2B , Figure 3B As shown, after the main color is applied, the coating range of the decorative coating 202 and the surface of the workpiece 201 that may not be coated with the decorative coating 202 are all covered by the main color coating 203 .

[0063] Varnish coating is a commonly used material at present. The varnish coating 204 is basically transparent, and the color and appearance of the coating below the varnish coating 204 can be presented. Fig. 6A and Figure 6B As shown, the primary color coating 203 below and the decorative coating 202 exposed after cleaning in the decorative area 206 can be seen through the varnish coating 204. The varnish coating 204 covers the entire surface of the workpiece 201. After the varnish is applied, the composite coating generally needs to be dried.

[0064] It is further configured as follows: heating and drying the workpiece 201 includes: hot air heating or infrared heating of the workpiece 201. The drying equipment is one of a fixed drying furnace, a fixed infrared baking lamp, and an infrared baking lamp driven by a multi-axis robotic arm. For water-based paint and 3C1B mid-coat, the drying temperature is set to 60℃~80℃; for the composite coating after spraying low-temperature varnish, the drying temperature is set to 70℃~90℃; for 3C2B mid-coat and the composite coating after spraying high-temperature varnish, the drying temperature is set to 130℃~150℃. The drying range is the wet film coating area or the entire workpiece 201, wherein the wet film coating area is the area sprayed with decorative paint, primary color paint and varnish.

[0065] Specifically, the volatile components in the coating are removed by heating to obtain a uniform and dense coating. The drying method can be hot air heating or infrared heating. The drying equipment can be a fixed drying furnace, an infrared baking lamp, etc., or a mobile equipment, such as an infrared baking lamp driven by a multi-axis robot arm, which can achieve the effect of heating and drying the coating by moving on the surface of the workpiece 201.

[0066] The drying temperature varies according to different processes and different coating requirements. For water-based paint, 3C1B mid-coat, etc., the general drying temperature is 60℃~80℃. For composite coatings after spraying low-temperature varnish, the general drying temperature is 70℃~90℃. For 3C2B mid-coat and composite coatings after spraying high-temperature varnish, the drying temperature is generally in the range of 130℃~150℃. With the development of coating processes and materials, as well as carbon emission requirements, drying temperatures outside the above-described temperature range may be developed in the future.

[0067] The drying range may cover only the wet film coating area, or cover the entire workpiece 201. For the workpiece 201 coated with the primary color coating 203 or the clear coating 204, the wet film coating covers the entire workpiece 201, and the drying range is therefore also the entire workpiece 201. Fig.16 An optional drying step is performed after the decorative color painting step. At this time, only the decorative coating 202 wet film is on the workpiece 201 . The drying range can be selected to cover only the decorative coating 202 wet film area or the entire workpiece 201 .

[0068] It is further configured as follows: the multi-axis robot arm guides the laser cleaning device 401 to move along a preset trajectory, and the laser cleaning device 401 controls the laser beam 402 to move within a set width range perpendicular to the moving direction, wherein the coating removal thickness 207 of the laser cleaning device 401 is greater than the maximum film thickness of the primary color coating 203 in the decorative area 206. The parameters of the laser cleaning device 401 are adjusted to control the coating removal thickness 207, wherein the parameters include power and moving speed, and the coating removal thickness 207 is greater than the maximum film thickness of the primary color coating 203 in the decorative area 206.

[0069] Specifically, FIG. 4A to FIG. 5B An embodiment of the laser removal step S105 is shown.

[0070] The laser cleaning device 401 is a type of laser ablation device, and is a processing device that removes material from the surface of the workpiece 201 by irradiating it with a laser beam 402. The laser cleaning device 401 is guided by a multi-axis robot arm (not shown in the figure). The laser cleaning device 401 is guided by a multi-axis robot arm to move along a preset trajectory. The laser cleaning device 401 can control the laser beam 402 to move within a set width range perpendicular to the moving direction. With the movement of the laser cleaning device 401 and the adjustment of the width of the movement of the laser beam 402, the decorative area 206 with different patterns can be cleaned. Figure 4B , Figure 5B FIG. 4 shows that when the width of the laser beam 402 is not adjusted, a rectangular decoration area 206 can be cleaned.

[0071] By adjusting the parameters of the laser cleaning device 401 , including but not limited to power, moving speed, etc., the coating removal thickness 207 can be controlled.

[0072] Under the condition that the coating process parameters remain unchanged, the thickness of the primary color coating 203 coated by the atomizing coating equipment 301 is not completely consistent, and the maximum error may reach more than 20%. In order to ensure that the decorative coating 202 is completely exposed after cleaning, the coating removal thickness 207 must be greater than the maximum film thickness of the primary color coating 203 in the decorative area 206. Figure 4A , Figure 5A shows a cross-sectional view of the composite coating before and after cleaning, Figure 4A The film thickness of the middle primary color coating 203 does not reach the maximum film thickness. Figure 5A The middle portion of the decorative coating 202 is also removed.

[0073] It is further configured that: when the width of the decoration area 206 perpendicular to the movement direction of the laser cleaning device 401 is greater than the maximum width of the movement of the laser beam 402, the decoration area 206 is divided into at least two areas in the width direction, and then the laser cleaning device 401 is used for cleaning, wherein one area corresponds to one cleaning path. An overlap width 405 is set in the boundary area between two adjacent cleaning paths, and when cleaning is performed, the removal thickness is linearly reduced to zero within the overlap width 405.

[0074] Specifically, when the width of the decoration area 206 perpendicular to the movement direction of the laser cleaning device 401 is greater than the maximum width of the laser beam 402, the decoration area 206 needs to be divided into several areas in the width direction and cleaned multiple times using the laser cleaning device 401. Fig. 7A , Figure 7B As shown, the width of the decoration area 206 is divided into a first cleaning path width 403 and a second cleaning path width 404 .

[0075] like Fig. 8A , Figure 8B As shown, the first cleaning path coating removal effect 406 and the second cleaning path coating removal effect 407 are originally uniform in the width range of the base coating removal thickness 207, and the combined coating removal effect 408 after the combination of the two is also uniform in the width range of the coating removal thickness 207.

[0076] There is an error between the actual position and the theoretical position of the multi-axis robot during movement, and the general repeated positioning error 409 is greater than 0.05mm.

[0077] Fig. 9A , Fig. 9B It shows the cleaning effect when the spacing between two adjacent cleaning paths is smaller than the theoretical spacing. When the spacing between the cleaning paths becomes smaller and the repeated positioning error 409 occurs, some cleaning areas will overlap. The combined coating removal effect 408 shows that the coating removal thickness 207 in this area is twice that of other non-overlapping areas, and a slender depression with a width equal to the repeated positioning error 409 and a depth equal to the coating removal thickness 207 will be formed on the decorative coating 202.

[0078] Fig. 10A , Fig. 10B The cleaning effect is shown when the spacing between two adjacent cleaning paths is greater than the theoretical spacing. When the spacing between the cleaning paths increases and the repeat positioning error 409 increases, the combined coating removal effect 408 is partially 0 in the adjacent area, and a thin and long protrusion with a width equal to the repeat positioning error 409 and a height equal to the coating removal thickness 207 is formed on the decorative coating 202. The thin and long protrusion looks like a hair, which is considered a coating defect.

[0079] One way to solve the above problem is to set a certain overlap width 405 in the boundary area between two adjacent cleaning paths, and the cleaning path coating removal thickness 207 is linearly reduced to 0 within the overlap width 405.

[0080] like Fig.11A , 11B As shown, the decoration area 206 is divided into two cleanings, and the first cleaning path width 403 and the second cleaning path width 404 have an overlapping width 405 of a certain distance.

[0081] like Fig. 12A , 12B As shown, the first cleaning path coating removal effect 406 and the second cleaning path coating removal effect 407 gradually decrease to 0 within the overlap width 405. When the spacing between two adjacent cleaning paths is equal to the theoretical spacing, the combined coating removal effect 408 has a uniform coating removal thickness 207 within the width range.

[0082] Fig.13A , Fig. 13B It shows the cleaning effect when the spacing between two adjacent cleaning paths is smaller than the theoretical spacing. When the spacing between the cleaning paths becomes smaller and the repeated positioning error 409 is reduced, the combined coating removal effect 408 decreases the coating removal thickness 207 within a certain width range, and a thickness bulge will be formed on the decorative coating 202.

[0083] Fig.14A , Fig. 14B It shows the cleaning effect when the spacing between two adjacent cleaning paths is greater than the theoretical spacing. When the spacing between the cleaning paths increases and the repeated positioning error 409 occurs, the combined coating removal effect 408 increases the coating removal thickness 207 within a certain width range, and a depression of thickness Y is formed on the decorative coating 202.

[0084] The following is the calculation formula for the thickness of a convex or concave area: Wherein, Y is the protrusion or depression thickness, H is the coating removal thickness 207, L is the overlap width 405, and X is the repeat positioning error 409.

[0085] For example, if the coating removal thickness 207 is 20 μm, the repeatability error 409 is 50 μm, and the overlap width 405 is 950 μm, the convex or concave thickness Y = 1 μm is calculated. The thickness becomes 1 / 20 of the convex or concave thickness of 20 μm before the above solution is adopted, and such a small difference cannot be detected visually.

[0086] Fig.15The device principle of the print head 501 involved in the second possible method for applying the decorative coating 202 is shown, and the coating is ejected from the micropore 502 array to form a continuous or intermittent coating jet 503, which falls on the surface of the workpiece 201 to form a coating. The size of the micropore 502 is generally below 100μm, while the diameter of the aluminum powder or pearl powder in the common coating for the car body is 10-75μm. The size difference between the two is not large, which can easily lead to the blockage of the micropore 502. Therefore, the print head 501 cannot directly use the coating commonly used for the car body, and special coating needs to be developed.

[0087] Fig.16 The second coating process step is shown. The coating method of the decorative coating 202 of the present invention is combined with the conventional non-color 3C2B or 3C1B process to realize the co-production of non-color and color body of the 3C2B or 3C1B coating process. The process route on the left is the process step of the non-color body, and the process route on the right is the process step of the color body. One optimization option is to add a drying step after the decorative color coating step.

[0088] Fig.17 The third coating process step is shown. Combining the coating method of the decorative coating 202 of the present invention with the conventional non-color B1B2 process can realize the co-production of non-color and color-coated body in the B1B2 coating process. The process route on the left is the process step of the non-color body, and the process route on the right is the process step of the body. One optimization option is to add a drying step after the decorative color coating step. Another optimization option is to add a drying step after the BC1 spraying step.

[0089] The working principle and beneficial effects of the present invention are as follows: through a fully automated process, from the coating of decorative coatings to primary color coatings to varnishes, as well as subsequent laser cleaning and re-drying, the entire process does not require manual intervention, significantly improving the production cycle and ensuring efficiency and stability under large-scale production. The process does not require the development of special coating equipment or materials, reducing the initial equipment investment cost. Laser cleaning technology only consumes electricity, and does not require chemical solvents or a large amount of water resources required for traditional cleaning. It is both environmentally friendly and economical, and further reduces operating costs. By first coating a larger decorative coating 202 on the surface of the workpiece 201, and then using a laser to accurately remove the excess coating of the non-decorated area 206, not only the precise definition of the decorative area 206 is achieved, but also the effect pigments such as aluminum powder and pearl powder can be flexibly used to enhance the decorative effect and meet the diverse and personalized aesthetic needs. The process is applicable to the surfaces of workpieces 201 of various materials, including metals, polymer materials, composite materials and different coating stages (such as electrophoretic coatings, primers to varnish layers), showing a wide range of material compatibility and process flexibility, and is applicable to a variety of industrial coating scenarios.

[0090] In summary, this technical solution not only greatly improves production efficiency and quality stability, but also maximizes economic benefits through resource conservation and cost control, while ensuring the diversity and high-end nature of decorative effects. It is an important technological innovation in the field of modern industrial coatings.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coating method, characterized in that: include: Step S101, applying a decorative coating to the surface of a workpiece (201) to obtain a decorative coating (202), wherein the range of the decorative coating (202) is larger than the range of a decorative area (206) on the surface of the workpiece (201), wherein the surface of the workpiece (201) is one of metal, polymer material, composite material, electrophoretic coating, primer coating, mid-coat coating, color paint coating or clear coat (204); Step S102, applying a primary color coating to the surface of the workpiece (201) to obtain a primary color coating (203), wherein the primary color coating (203) covers the entire surface of the workpiece (201); Step S103, heating and drying the workpiece (201); Step S104, using a laser cleaning device (401) to remove the primary color coating (203) on the decorative area (206) and a portion of the decorative coating (202) on the decorative area (206); Step S105, applying varnish to the surface of the workpiece (201) to obtain a varnish coating (204), wherein the varnish coating (204) covers the entire surface of the workpiece (201); Step S106, heating and drying the workpiece (201).

2. The coating method according to claim 1, characterized in that: include: The decorative paint, the primary color paint and the clear varnish are applied using an atomizing coating device (301), wherein the atomizing coating device (301) comprises a rotary cup atomizer and an air atomizing spray gun; The multi-axis mechanical arm guides the atomization coating device (301) to move along a preset trajectory, atomizes the coating into paint mist (302), and transfers the paint mist to the surface of the workpiece (201).

3. The coating method according to claim 1, characterized in that: Heating and drying a workpiece (201), comprising: Heating and drying the workpiece (201) includes: heating the workpiece (201) with hot air or infrared heating.

4. The coating method according to claim 1, characterized in that: Heating and drying a workpiece (201), comprising: The drying equipment is a fixed drying furnace, a fixed infrared baking lamp, and an infrared baking lamp driven by a multi-axis robotic arm.

5. The coating method according to claim 1, characterized in that: Heating and drying a workpiece (201), comprising: For water-based paint and 3C1B midcoat, the drying temperature is set at 60℃~80℃; For composite coatings after spraying low-temperature varnish, the drying temperature is set at 70℃~90℃; For the composite coating of 3C2B intermediate coating and high temperature clear coating, the drying temperature is set at 130℃~150℃.

6. The coating method according to claim 1, characterized in that: Heating and drying a workpiece (201), comprising: The drying range is the wet film coating area or the entire workpiece (201), wherein the wet film coating area is the area sprayed with the decorative paint, the main color paint and the clear paint.

7. The coating method according to claim 1, characterized in that: Using a laser cleaning device (401) to remove the primary color coating (203) on the decorative area (206) and a portion of the decorative coating (202) on the decorative area (206), comprising: The multi-axis robot arm guides the laser cleaning device (401) to move along a preset trajectory, and the laser cleaning device (401) controls the laser beam (402) to move within a set width range perpendicular to the moving direction, wherein the coating removal thickness (207) of the laser cleaning device (401) is greater than the maximum film thickness of the main color coating (203) in the decorative area (206).

8. The coating method according to claim 7, characterized in that: The multi-axis mechanical arm guides the laser cleaning device (401) to move along a preset trajectory, and the laser cleaning device (401) controls the laser beam (402) to move within a set width range perpendicular to the moving direction, including: The parameters of the laser cleaning device (401) are adjusted to control the coating removal thickness (207), wherein the parameters include power and moving speed, and the coating removal thickness (207) is greater than the maximum film thickness of the primary color coating (203) in the decorative area (206).

9. The coating method according to claim 8, characterized in that: Using a laser cleaning device (401) to remove the primary color coating (203) on the decorative area (206) and a portion of the decorative coating (202) on the decorative area (206), comprising: When the width of the decoration area (206) perpendicular to the movement direction of the laser cleaning device (401) is greater than the maximum width of the movement of the laser beam (402), the decoration area (206) is divided into at least two areas in the width direction and then cleaned using the laser cleaning device (401), wherein one area corresponds to one cleaning path.

10. The coating method according to claim 9, characterized in that: When the width of the decoration area (206) perpendicular to the movement direction of the laser cleaning device (401) is greater than the maximum width of the movement of the laser beam (402), the decoration area (206) is divided into at least two areas in the width direction, and then the laser cleaning device (401) is used for cleaning, comprising: An overlap width (405) is provided in the boundary area between two adjacent cleaning paths, and when cleaning is performed, the removal thickness is linearly reduced to zero within the overlap width (405).

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