Loudspeaker mesh local shielding paint spraying system and paint spraying process thereof

Abstract

The invention relates to a speaker mesh local shielding paint spraying system and a paint spraying process thereof, and belongs to the technical field of surface coating processing, the speaker mesh local shielding paint spraying system comprises a spraying chamber, a conveying device, a paint spraying device, a shielding device and a control device; the shielding device comprises a shielding mold, a mold driving mechanism, a positioning sensor and a mold cleaning mechanism; the shielding mold is made of a flexible temperature-resistant material, and the working face of the shielding mold is provided with a protruding structure profiling a loudspeaker mesh area and used for being tightly attached to the loudspeaker mesh area to form physical shielding during paint spraying. The paint spraying device comprises a multi-axis linkage mechanical arm and an atomizing spray gun installed on the multi-axis linkage mechanical arm. The invention further provides a paint spraying process based on the system. According to the invention, precise local shielding of the speaker mesh is realized through the profiling shielding mold, the problems of low efficiency and poor positioning precision of a traditional film pasting mode are avoided, paint collection of the mesh is effectively prevented, the acoustic permeability of the speaker mesh is ensured, and the production efficiency and the product quality are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface coating processing, in particular to a local shielding paint spraying system for a horn mesh and a paint spraying process thereof. BACKGROUND

[0002] A horn mesh is a common component in products such as audio, automobile, and consumer electronics, and its main function is to protect the internal loudspeaker while ensuring effective sound transmission. In order to meet the requirements of product appearance beautification and corrosion resistance, surface paint spraying treatment is usually performed on the horn mesh and its surrounding shell. However, the surface of the horn mesh is densely covered with small mesh holes (common aperture is 0.5-1.5mm), and if the entire horn mesh is directly sprayed, the paint is easy to block the mesh holes, causing the sound transmission to be blocked, which seriously affects the acoustic performance. This problem is known as the "paint collection" problem.

[0003] In view of the paint collection problem in the process of spraying the horn mesh, the existing technology mainly explores three technical routes: one is the process parameter control route, such as the Chinese patent with publication number CN102601029B, which discloses a paint spraying and coating process applied to a mobile phone horn mesh. Through a multi-layer process of spraying primer, vacuum coating, spraying intermediate paint, and spraying topcoat, and precisely controlling the thickness of each layer of paint film (primer 7±1um, intermediate paint 5±1um, topcoat 12±1um), the performance and appearance effect of the horn mesh are ensured. This scheme reduces the risk of mesh hole blockage by controlling the film thickness, but it is still a full-surface spraying in essence. For horn meshes with smaller aperture or higher opening rate, even if the film thickness is strictly controlled, paint mist may still enter the mesh holes and cause blockage, and the shielding problem of the mesh hole area cannot be solved from the root cause.

[0004] The second is the material formula route, such as the Chinese patent application with publication number CN119019898A, which discloses a metal horn cover coating for automotive interior and a preparation method thereof. It uses a specific solid content and hydroxyl value of hydroxyl acrylate resin mixed and matched, claiming that "there will be no mesh cover gap paint collection problem after spraying". This scheme relies on a special coating formula to reduce paint collection by improving leveling and reducing viscosity, but for mesh holes with large depth-diameter ratio or complex curved mesh covers, it is difficult to completely eliminate paint collection by improving rheological properties alone. Moreover, this scheme has limited scope of application, and different horn meshes of different materials and different apertures may require different coating formulas, which has poor universality.

[0005] Thirdly, there are optimization approaches for clamps / hangers. For example, Chinese patent CN219785275U discloses a spraying device for car horn covers. By setting an adjustable L-shaped clamping plate and a rotating mechanism, it achieves clamping and spraying angle adjustment for horn covers of different sizes. Another example is Chinese patent CN222428313U, which discloses a spraying hanger structure for uniform oil film thickness. By setting baffles on both sides of the frame, the baffles adsorb paint, avoiding excessive paint accumulation on the outer edges and sharp corners of the horn mesh. These solutions mainly improve spraying quality by improving the clamping method and optimizing the uniformity of film thickness. However, none of them address the problem of local masking in the horn mesh area. They fail to provide a direct and effective solution to the core problem of mesh blockage.

[0006] In actual industrial production, the more common method to solve the painting problem in the speaker grille area is to use manual film application for masking. That is, the protective film is manually applied to the speaker grille area before painting, and then removed after painting. However, this method has the following inherent drawbacks: First, manual film application is inefficient (about 2 minutes per piece), making it difficult to adapt to automated mass production; second, the positioning accuracy of the film application depends on the operator's experience, which can easily lead to problems such as paint seepage at the edges or incomplete masking; third, for irregularly shaped or curved speaker grilles, the protective film is difficult to adhere tightly, resulting in poor masking effect; and fourth, the film application and removal process can easily damage the workpiece surface or the cured paint film.

[0007] Therefore, developing a painting system and process that can achieve precise local masking of the speaker grille area, is suitable for automated production, and can adapt to complex curved shapes has become an urgent technical problem to be solved in this field. Summary of the Invention

[0008] This invention provides a partial masking and painting system for speaker grilles and its painting process, which solves the problems of easy clogging of mesh holes, low masking efficiency, and poor positioning accuracy in the prior art when painting speaker grilles.

[0009] The solution of the present invention to solve the above-mentioned technical problems is as follows: a partial masking spray painting system for speaker grilles and its spray painting process, including a spraying chamber, a conveying device, a spraying device, a masking device, and a control device, wherein the interior of the spraying chamber forms a closed spraying space;

[0010] The conveying device is installed throughout the spraying chamber. The conveying device includes a conveyor chain and workpiece clamps evenly arranged on the conveyor chain, which are used to carry and convey the horn mesh workpieces.

[0011] The painting device is located in the spraying chamber and includes a multi-axis linkage robotic arm and an atomizing spray gun installed at the end of the robotic arm.

[0012] The shielding device is installed in the spraying chamber and located upstream of the working station of the spraying device, and includes a shielding mold, a mold driving mechanism and a positioning sensor;

[0013] The masking mold is made of flexible heat-resistant material, and its working surface is provided with contoured protrusions that match the shape of the speaker mesh area. The mold driving mechanism is connected to the masking mold for driving the masking mold to fit tightly or separate from the speaker mesh area to be sprayed at the masking station. The positioning sensor is used to detect the position of the speaker mesh workpiece.

[0014] The control device is electrically connected to the conveying device, the painting device, and the masking device, and is used to receive signals from the positioning sensor and control the coordinated operation of each device.

[0015] The painting process includes the following steps:

[0016] S1, loading and positioning: the workpiece to be sprayed is fixed on the workpiece clamp of the conveying device and sent into the spraying chamber by the conveying device.

[0017] S2, Automatic Masking: When the positioning sensor detects that the workpiece has reached the masking station, the control device issues a command to drive the mold drive mechanism to move the masking mold toward the speaker mesh workpiece, so that the contour protrusions fit tightly against the speaker mesh hole area to form local physical masking.

[0018] S3, painting. After masking is completed, the workpiece enters the painting station. The control device starts the painting device. The multi-axis linkage robotic arm drives the atomizing spray gun to spray the workpiece surface evenly according to the preset trajectory. During the painting process, the workpiece clamp drives the workpiece to rotate.

[0019] S4, Pre-curing: After spraying, the workpiece passes through the infrared pre-curing zone during transportation, allowing the paint film to initially dry.

[0020] S5, Mold Separation and Cleaning: The workpiece enters the mold separation station, the mold drive mechanism drives the shielding mold to separate from the workpiece and reset, and then the mold cleaning mechanism cleans the working surface of the shielding mold to remove the attached paint mist.

[0021] S6, Overall Curing: The workpiece that has been separated from the masking mold is continued to be transported to the curing oven for overall drying and curing.

[0022] S7, unloading: After curing, the workpiece is output via a conveyor to complete the spraying process.

[0023] Based on the above technical solution, the present invention can be further improved as follows.

[0024] Furthermore, the masking device also includes a mold cleaning mechanism, which is located downstream of the spraying station and beside the reset path of the masking mold. The mold cleaning mechanism includes a cleaning brush and a high-pressure air nozzle, used to remove paint mist adhering to the working surface of the masking mold after it is reset. The mold cleaning mechanism can automatically remove residual paint mist on the surface of the masking mold online, avoiding paint mist accumulation that could lead to a decrease in mold conformation accuracy or difficulty in demolding. This ensures the reusability of the mold in continuous production, extends the mold's service life, and ensures the tightness and positional accuracy of each masking operation, maintaining a stable masking effect and improving production cycle time and yield.

[0025] Furthermore, the masking mold is made of silicone rubber or fluororubber with a Shore hardness of 30-70HA and a temperature resistance of ≥150℃. Using flexible, temperature-resistant materials such as silicone rubber or fluororubber allows the masking mold to undergo appropriate elastic deformation under pressure, achieving a tight fit with the complex curved surface of the speaker mesh area and effectively preventing paint seepage at the edges. The hardness is controlled within the 30-70HA range, ensuring sufficient support to resist the impact of the spraying airflow while also possessing good flexibility to adapt to the microscopic unevenness of the workpiece surface. The temperature resistance of ≥150℃ can withstand the temperatures during spraying and pre-curing processes, preventing mold deformation due to high-temperature aging and ensuring dimensional stability and masking reliability during long-term use.

[0026] Furthermore, the surface of the contoured protrusion is provided with a release layer, which is a Teflon coating or a nano-ceramic coating. The release layer significantly reduces the adhesion between the paint and the mold surface, making the separation of the mold and the workpiece after painting smoother and reducing paint film damage or mold deformation caused by adhesion. The Teflon coating or nano-ceramic coating has excellent wear resistance and chemical inertness, and can withstand repeated cleaning by cleaning brushes and high-pressure airflow without damage, extending the mold life. At the same time, it ensures that the mold surface remains clean after each demolding, eliminating the need for frequent mold replacement and reducing operating costs.

[0027] Furthermore, the workpiece fixture is a rotary fixture, which can drive the horn mesh workpiece to rotate at the spraying station. The rotary fixture causes the workpiece to rotate around its own axis during the spraying process. Combined with the contouring motion of the multi-axis robotic arm, it can achieve uniform coverage of the circumferential surface of the workpiece, eliminate spraying dead corners, and is particularly suitable for cylindrical or horn mesh structures with annular features, ensuring consistent paint film thickness and appearance quality. At the same time, the rotational motion helps the atomized paint droplets to level on the workpiece surface, improving the coating gloss and adhesion.

[0028] Furthermore, the painting device also includes a paint supply unit and an air supply unit, which are respectively connected to the atomizing spray gun. The paint supply unit is equipped with a flow controller. The independent setting of the paint supply unit and the air supply unit, as well as the introduction of the flow controller, enables precise adjustment of the paint output and atomizing air pressure during the spraying process. It can optimize the spraying parameters for horn mesh workpieces of different shapes and materials, ensuring that the paint film thickness is within the set tolerance range (e.g., ±3μm), and avoiding uneven film thickness or sagging defects caused by unstable paint supply. The closed-loop adjustment function of the flow controller can automatically match the paint supply according to the spraying speed, further improving the spraying accuracy and paint utilization rate.

[0029] Furthermore, in step S2, the bonding pressure between the masking mold and the speaker mesh area is controlled at 0.1-0.5 MPa, and the bonding time continues until the spraying process is completed. Controlling the bonding pressure within this range ensures that the mold's contoured protrusions and the mesh edge form an effective seal, preventing paint mist from seeping in, while also preventing workpiece deformation or mold damage due to excessive pressure. Maintaining the pressure until the end of spraying prevents the mold from shifting due to vibration or airflow impact during the spraying process, ensuring the reliability of the masking. This pressure range has been experimentally verified to be applicable to most plastic and metal speaker mesh workpieces, demonstrating good process versatility.

[0030] Furthermore, in step S3, the spraying parameters are set as follows: coating air pressure 2.5-3.5 kg / cm², atomizing air pressure 4-5 kg / cm², spray gun moving speed 200-400 mm / s, and spraying distance 150-250 mm. The above parameter range is based on the comprehensive optimization of paint atomization characteristics, paint film thickness control, and spraying efficiency: the combination of coating air pressure and atomizing air pressure can form a uniform and fine paint mist, reducing orange peel phenomenon; the spray gun moving speed is controlled at 2-4 mm / s (relatively slow), which is conducive to achieving precise film thickness control and complex curved surface contour spraying, ensuring uniform coating in details such as mesh edges; the spraying distance of 150-250 mm takes into account both paint mist scattering loss and coating coverage efficiency, and the best transfer efficiency and coating quality can be obtained within this range.

[0031] Furthermore, in step S4, the pre-curing temperature is 60-80℃ and the time is 3-5 minutes; in step S6, the overall curing temperature is 70-90℃ and the time is 20-30 minutes. The pre-curing stage uses a relatively mild temperature and a short time to allow the paint film to reach a surface-dry state, which ensures that the paint film is not damaged when the mold is separated later, and avoids the paint film from becoming brittle due to over-curing at high temperatures. The overall curing stage uses a slightly higher temperature and a longer time to ensure that the paint film is completely cross-linked and achieves the designed hardness and weather resistance indicators. The two-step curing process optimizes the production line cycle while ensuring the coating performance, and realizes continuous production.

[0032] The beneficial effects of this invention are as follows: This invention provides a partial masking and painting system for speaker grilles and its painting process, which has the following advantages:

[0033] 1. By setting up a flexible masking mold that conforms to the shape of the speaker mesh area, precise local masking of the mesh area is achieved, which effectively prevents the mesh from clogging during the painting process and ensures the acoustic transparency of the speaker mesh.

[0034] 2. By adopting an automated masking mechanism in conjunction with positioning sensors, fully automated operations of masking, painting, separation, and cleaning are achieved, which greatly improves production efficiency and saves labor costs;

[0035] 3. The mold cleaning mechanism ensures the accuracy of repeated use of the shielding mold, extends the mold's service life, and reduces production costs;

[0036] 4. The multi-axis linkage robotic arm, in conjunction with the rotating fixture, enables uniform spraying of complex curved surface speaker grilles, effectively improving coating quality. The design of pre-curing and overall curing in stages ensures both the integrity of the paint film when the mold is separated and the final curing effect of the coating.

[0037] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail in the following embodiments and their accompanying drawings. Attached Figure Description

[0038] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0039] Figure 1 This is a schematic diagram of a speaker grille partial masking spray painting system and its spray painting process provided in an embodiment of the present invention;

[0040] Figure 2 A front view of a speaker grille partial masking spray painting system and its spray painting process provided in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the structure of a speaker mesh partial masking spray painting system and the conveying device in the spray painting process provided in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the structure of a speaker grille partial masking spray painting system and the masking device in the spray painting process provided in an embodiment of the present invention;

[0043] Figure 5This is a schematic diagram of the structure of a speaker grille partial masking spray painting system and the masking mold in the spray painting process, provided as an embodiment of the present invention.

[0044] The attached diagram lists the components represented by each number as follows:

[0045] 1. Spraying chamber; 2. Conveying device; 201. Conveyor chain; 202. Workpiece fixture; 3. Painting device; 301. Multi-axis linkage robotic arm; 302. Atomizing spray gun; 303. Paint supply unit; 3031. Flow controller; 304. Air supply unit; 4. Masking device; 401. Masking mold; 4011. Contouring protrusion; 402. Mold drive mechanism; 403. Positioning sensor; 404. Mold cleaning mechanism; 4041. Cleaning brush; 4042. High-pressure air nozzle; 5. Control device. Detailed Implementation

[0046] The following is in conjunction with the appendix Figures 1-5 The principles and features of the present invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] like Figures 1-5 As shown, the present invention provides a partial masking spray painting system for speaker grilles and its spray painting process, including a spray booth 1, a conveying device 2, a spray painting device 3, a masking device 4 and a control device 5. The spray booth 1 is a closed structure, forming an independent spraying space inside, which is used to isolate paint mist and maintain a stable spraying environment. The side wall of the spray booth 1 is provided with an opening for the conveying device 2 to pass through, and is equipped with an air curtain or sealing curtain to reduce paint mist leakage.

[0049] The conveying device 2 is installed throughout the spraying chamber 1, including a conveyor chain 201 and multiple workpiece clamps 202 evenly spaced on the conveyor chain 201. The conveyor chain 201 is driven by a servo motor and can realize intermittent or continuous conveying with adjustable running speed. The workpiece clamps 202 are used to carry and fix the horn mesh workpieces to be sprayed. In this embodiment, the workpiece clamp 202 is a rotating clamp with a micro motor and transmission mechanism in its base. Under the control of the control device 5, it can drive the workpiece to rotate around its own axis with a speed range of 5-20 rpm to adapt to the spraying requirements of workpieces with different shapes.

[0050] The painting device 3 is located inside the spraying chamber 1 and includes a multi-axis linkage robotic arm 301, an atomizing spray gun 302, a paint supply unit 303, and an air supply unit 304. The multi-axis linkage robotic arm 301 is a six-axis industrial robot with an atomizing spray gun 302 installed at its end, which can achieve precise movement along any trajectory in space. The paint supply unit 303 is connected to the atomizing spray gun 302 through pipelines and is equipped with a flow controller 3031 (such as a mass flow meter or a precision gear pump) inside, which is used to adjust the paint output in real time. The flow control accuracy can reach ±1%. The air supply unit 304 provides compressed air, which is divided into two paths, coating air and atomizing air, after passing through a pressure regulating valve and a filter. These paths are connected to the atomizing spray gun 302 respectively. The coating air pressure and the atomizing air pressure can be adjusted independently.

[0051] The masking device 4 is installed inside the spray booth 1, upstream of the working station of the painting device 3. It includes a masking mold 401, a mold driving mechanism 402, a positioning sensor 403, and a mold cleaning mechanism 404. The positioning sensor 403 is a photoelectric sensor or a machine vision system, installed beside the masking station, used to accurately detect the position of the workpiece on the conveyor chain 201 and identify the workpiece model. The mold driving mechanism 402 is a servo electric cylinder or a pneumatic cylinder, which is connected to the masking mold 401 and can drive the masking mold 401 to move back and forth along the guide rail to achieve contact and separation with the workpiece. The masking mold 401 is made of flexible heat-resistant material. Made of silicone rubber, with a Shore hardness of 50HA and a temperature resistance of ≥200℃, the working surface of which is provided with contoured protrusions 4011 that precisely match the shape of the horn mesh area. The surface of the contoured protrusions 4011 is coated with a Teflon release layer. The mold cleaning mechanism 404 is located downstream of the spraying station and beside the reset path of the shielded mold 401. It includes a rotating cleaning brush 4041 driven by a motor and a set of high-pressure air nozzles 4042. The bristles of the cleaning brush 4041 are made of antistatic nylon material. The high-pressure air nozzles 4042 spray compressed air at a pressure of 0.4-0.6MPa to blow away the paint mist and dust brushed off.

[0052] It should be noted that the contoured protrusion 4011 described in this application is not intended to be embedded inside each tiny mesh opening, but rather designed to form surface contact with the non-perforated skeleton portion (i.e., the ribs between the mesh openings) of the horn mesh area. When the mold drive mechanism (402) applies a bonding pressure of 0.1-0.5 MPa, the contoured protrusion (4011) made of a flexible material (such as silicone rubber) will undergo micron-level elastic deformation, thereby tightly adhering to the surface of the mesh skeleton and forming an effective physical sealing ring that covers the entire mesh area from above. This design avoids demolding difficulties or mold damage that may result from the protrusion embedding into the mesh opening, and also ensures the anti-seepage effect of the paint at the edges through flexible sealing.

[0053] The control device 5 is a PLC controller or industrial control computer, which is electrically connected to the drive motor of the conveying device 2, the robotic arm controller and paint supply unit of the painting device 3, the drive mechanism and sensors of the masking device 4, etc. The control device 5 receives the signal from the positioning sensor 403 and coordinates the action sequence of each device according to the preset program to achieve fully automatic cycle.

[0054] The core control logic of the control device (5) includes: First, receiving the trigger signal from the positioning sensor (403) to lock the real-time position of the current workpiece on the conveyor chain (201); Second, according to the preset rhythm, issuing a command to the mold drive mechanism (402) to synchronize its movement with the conveyor chain (201), pushing the shielding mold (401) to briefly synchronize with the moving workpiece and complete the fitting; Third, at the spraying station, controlling the trajectory of the multi-axis linkage robotic arm (301), the start and stop of the atomizing spray gun (302), and the rotation of the workpiece clamp (202) to achieve contour spraying; Finally, after the mold is separated, triggering the brushing and blowing action of the mold cleaning mechanism (404). The entire process is realized through the closed-loop control module of the PLC to ensure the precise timing coordination of each actuator.

[0055] Example 1: The specific working principle and usage method of the present invention are as follows:

[0056] S1, Loading and Positioning: The operator clamps the plastic speaker mesh workpiece (mesh aperture 0.8mm, opening rate 45%) to be sprayed onto the workpiece fixture 202, starts the conveyor chain 201, and the workpiece enters the spraying chamber 1 at a constant speed (e.g., 2m / min).

[0057] S2, Automatic Masking: When the workpiece moves to the masking station with the conveyor chain 201, the positioning sensor 403 detects the workpiece arrival signal and sends it to the control device 5. The control device 5 immediately issues a command to drive the mold drive mechanism 402 to push the masking mold 401 towards the workpiece, so that the contour protrusion 4011 is tightly attached to the horn mesh area with a pressure of 0.3MPa, forming a local physical seal to prevent paint mist from entering the mesh during subsequent spraying. The attachment pressure is precisely controlled by the output of the mold drive mechanism 402 and maintained until the spraying process is completed.

[0058] S3, Painting: After masking is completed, the workpiece continues to move forward into the painting station. The control device 5 starts the painting device 3. The multi-axis linkage robotic arm 301 drives the atomizing spray gun 302 to uniformly spray the workpiece surface according to the preset trajectory. At the same time, the workpiece clamp 202 drives the workpiece to rotate at a speed of 10 rpm to ensure that the coating on the circumferential surface of the workpiece is uniform. The spraying parameters are set as follows: coating air pressure 3.0 kg / cm², atomizing air pressure 4.5 kg / cm², spray gun moving speed 300 mm / s, spraying distance 200 mm. The paint supply unit 303 stably supplies paint through the flow controller 3031, and the paint film thickness is controlled at 25 ± 3 μm.

[0059] S4, Pre-curing: After the spraying is completed, the workpiece passes through the infrared pre-curing zone downstream of the spraying chamber 1 during the conveying process. The infrared lamp power is adjustable, so that the surface temperature of the workpiece is raised to 70°C and maintained for 4 minutes. The paint film reaches the surface dry state (touch dry), which is convenient for subsequent mold separation without damaging the paint film.

[0060] S5, Mold Separation and Cleaning: When the workpiece enters the mold separation station, the control device 5 issues a command, and the mold drive mechanism 402 drives the masking mold 401 to move backward to separate from the workpiece and reset to the initial position. Subsequently, the mold cleaning mechanism 404 is started, and the rotating cleaning brush 4041 brushes the working surface of the masking mold 401. At the same time, the high-pressure air nozzle 4042 sprays compressed air to blow away residual paint mist, ensuring that the mold surface is clean and ready for the next masking.

[0061] High-pressure air nozzle 4042 ejects compressed air at 0.5 MPa. Since the paint mist is not yet fully cured (it has only undergone pre-curing and is in a surface-dry state), its adhesion to the Teflon release layer is weak. The mechanical brushing force of the rotating cleaning brush 4041 is sufficient to peel it off from the mold surface, where it is then blown away by the high-pressure airflow. Experiments have verified that this cleaning method can remove over 99% of residual paint mist, ensuring that the mold's conformation accuracy decreases by less than 0.05 mm after 500 consecutive production cycles.

[0062] S6, Overall Curing: The workpiece after mold separation continues to be transported to the curing oven. The temperature inside the curing oven is 80℃ and it is kept at that temperature for 25 minutes to allow the paint film to fully cross-link and cure, achieving the final hardness and adhesion.

[0063] S7, Unloading: The cured workpiece is output from the spraying chamber 1 via the conveyor device 2 and removed by the operator or the automatic unloading mechanism, thus completing the entire spraying process.

[0064] Example 2: To adapt to higher temperature spraying environments (such as baking coatings), the material of the masking mold 401 is replaced with fluororubber, the Shore hardness is adjusted to 65HA, the temperature resistance is ≥250℃, and the surface of the contour protrusion 4011 is coated with a nano-ceramic coating to further improve wear resistance and demolding properties.

[0065] In the spraying process, due to the high viscosity of the paint, the coating air pressure is adjusted to 3.5 kg / cm², the atomizing air pressure is 5.0 kg / cm², the spray gun moving speed is reduced to 250 mm / s, and the spraying distance is maintained at 200 mm to ensure atomization effect and film thickness uniformity. The pre-curing temperature is increased to 80°C for 3 minutes; the overall curing temperature is increased to 90°C for 20 minutes, and other steps are the same as in Example 1.

[0066] This embodiment was used to spray a metal speaker mesh workpiece (material: aluminum alloy, mesh diameter 1.2mm). It also achieved good masking effect and coating quality. After 1000 cycles of use, the mold did not show a significant decrease in conformation accuracy and the release layer was intact, which proves that the fluororubber mold combined with the nano-ceramic coating has a longer service life under high temperature conditions.

[0067] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Content not described in detail in this specification is prior art known to those skilled in the art.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any equivalent changes, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A partial masking and painting system for speaker grilles, comprising a spray booth (1), a conveying device (2), a painting device (3), a masking device (4), and a control device (5), characterized in that: The spraying chamber (1) forms a closed spraying space; The conveying device (2) is installed through the spraying chamber (1). The conveying device (2) includes a conveying chain (201) and workpiece clamps (202) uniformly arranged on the conveying chain (201) for carrying and conveying the speaker mesh workpiece. The painting device (3) is set in the spraying chamber (1) and includes a multi-axis linkage robotic arm (301) and an atomizing spray gun (302) installed at the end of the robotic arm (301). The masking device (4) is installed in the spraying chamber (1) and located upstream of the working station of the spraying device (3), including a masking mold (401), a mold driving mechanism (402) and a positioning sensor (403). The masking mold (401) is made of flexible heat-resistant material, and its working surface is provided with contoured protrusions (4011) that match the shape of the speaker mesh area. The mold driving mechanism (402) is connected to the masking mold (401) for driving the masking mold (401) to fit tightly or separate from the speaker mesh area to be sprayed at the masking station. The positioning sensor (403) is used to detect the position of the speaker mesh workpiece. The control device (5) is electrically connected to the conveying device (2), the painting device (3), and the masking device (4), and is used to receive signals from the positioning sensor (403) and control the coordinated actions of each device.

2. The speaker grille partial masking and painting system according to claim 1, characterized in that, The masking device (4) also includes a mold cleaning mechanism (404), which is located downstream of the spraying station and beside the reset path of the masking mold (401). The mold cleaning mechanism (404) includes a cleaning brush (4041) and a high-pressure air nozzle (4042) for removing paint mist adhering to the working surface of the masking mold (401) after it is reset.

3. The speaker grille partial masking and painting system according to claim 1, characterized in that, The shielding mold (401) is made of silicone rubber or fluororubber material, with a Shore hardness of 30-70HA and a temperature resistance of ≥150℃.

4. The speaker grille partial masking and painting system according to claim 1, characterized in that, The surface of the contoured protrusion (4011) is provided with a release layer, which is a Teflon coating or a nano-ceramic coating.

5. The speaker grille partial masking and painting system according to claim 1, characterized in that, The workpiece fixture (202) is a rotating fixture that can drive the speaker mesh workpiece to rotate at the spraying station.

6. The speaker grille partial masking and painting system according to claim 1, characterized in that, The painting device (3) further includes a paint supply unit (303) and an air supply unit (304), which are respectively connected to the atomizing spray gun (302), and the paint supply unit (303) is equipped with a flow controller (3031).

7. A partial masking and painting process for speaker grilles based on the system described in any one of claims 1-6, characterized in that, The steps include: S1, loading and positioning, fixing the workpiece to be sprayed on the workpiece clamp (202) of the conveying device (2), and sending it into the spraying chamber (1) by the conveying device (2); S2, Automatic masking: When the positioning sensor (403) detects that the workpiece has arrived at the masking station, the control device (5) issues a command to drive the mold drive mechanism (402) to move the masking mold (401) toward the speaker mesh workpiece, so that the contour protrusion (4011) fits tightly against the speaker mesh hole area to form a local physical masking. S3, painting. After the masking is completed, the workpiece enters the spraying station. The control device (5) starts the painting device (3). The multi-axis linkage robotic arm (301) drives the atomizing spray gun (302) to spray the workpiece surface evenly according to the preset trajectory. During the spraying process, the workpiece clamp (202) drives the workpiece to rotate. S4, Pre-curing: After spraying, the workpiece passes through the infrared pre-curing zone during transportation, allowing the paint film to initially dry. S5, mold separation and cleaning: the workpiece enters the mold separation station, the mold drive mechanism (402) drives the shielding mold (401) to separate from the workpiece and reset, and then the mold cleaning mechanism (404) cleans the working surface of the shielding mold (401) to remove the attached paint mist; S6, Overall Curing: The workpiece that has been separated from the masking mold is continued to be transported to the curing oven for overall drying and curing. S7, unload the workpiece. After curing, the workpiece is output through the conveying device (2) to complete the spraying process.

8. The partial masking and painting process for speaker grilles according to claim 7, characterized in that, In step S2, the bonding pressure between the masking mold (401) and the speaker mesh area is controlled at 0.1-0.5MPa, and the bonding time continues until the spraying process is completed.

9. The partial masking and painting process for speaker grilles according to claim 7, characterized in that, In step S3, the spraying parameters are set as follows: coating air pressure 2.5-3.5 kg / cm², atomizing air pressure 4-5 kg / cm², spray gun moving speed 200-400 mm / s, and spraying distance 150-250 mm.

10. The partial masking and painting process for speaker grilles according to claim 7, characterized in that, In step S4, the pre-curing temperature is 60-80℃ and the time is 3-5 minutes; in step S6, the overall curing temperature is 70-90℃ and the time is 20-30 minutes.

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