Valve spraying device enabling air to flow stably and using method

Abstract

The invention discloses a valve spraying device enabling air to flow stably and a using method, and belongs to the technical field of valve spraying. Comprising the steps that a rotatable C-shaped mechanical arm is supported through a portal frame, a paint spraying unit and a coaxial air curtain generation structure surrounding a nozzle of the paint spraying unit are arranged at one end of the mechanical arm, and the structure generates a high-speed laminar flow air curtain through pressurization of an impeller to wrap a paint mist beam; a negative pressure recovery cover and a fan are symmetrically arranged at the other end of the mechanical arm, so that the nozzle, the center of the workpiece and a recovery cover suction port form a three-point one-line layout, and directional negative pressure field constraint airflow is generated. According to the scheme, the problems that a paint mist track is unstable, paint waste is serious, spraying is missed at the complex structure of a valve body and a coating is uneven due to vortex turbulence of a common spray gun are effectively solved. The spraying device has the beneficial effects that the paint adsorption rate is remarkably increased, spraying dead angles are eliminated, the uniformity of a coating is ensured, overspray paint mist is efficiently recycled, pollution is reduced, and the spraying device is suitable for high-quality spraying of various valve bodies in complex geometrical shapes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of valve spraying, in particular to a valve spraying device with stable air flow and a use method. BACKGROUND

[0002] The conventional compressed air spray gun technology is generally used for valve spraying. However, this technology has significant defects in the interior of the spray gun and the outlet area of the nozzle. When the compressed air flows through the narrow channel in the interior of the spray gun and the suddenly expanded outlet, it is prone to generate intense vortex and turbulent flow. This unstable air flow state causes the movement trajectory of the atomized paint particles to be unpredictably deflected and scattered, which destroys the concentration and directionality of the paint mist beam.

[0003] The instability of the movement trajectory of the paint mist particles directly leads to two major problems. First, a large number of paint particles cannot effectively reach the surface of the workpiece, resulting in a serious waste of paint and significantly reducing the adsorption utilization rate of the paint. Second, and more importantly, when spraying complex valve workpieces, such as uneven valve disc surfaces or deep recessed valve rod slots, the unstable paint mist beam cannot effectively cover the leeward surface or recessed areas of these regions, resulting in the so-called "shadow effect". This leads to quality defects such as missed spraying or excessively thin coating in local areas, especially in recesses and corner back surfaces.

[0004] In addition, turbulence and vortex can also cause disturbances on the surface of the wet paint film that has been deposited but not yet solidified. This disturbance may, on the one hand, cause the sprayed air flow to bounce irregularly on the surface of the valve body, forming patches with uneven coating thickness; on the other hand, the high-speed turbulent air flow can interfere with the leveling process of the wet paint film, which is prone to induce surface defects such as "orange peel", seriously affecting the apparent quality and protective performance of the coating. SUMMARY

[0005] The purpose of the present application is to provide a valve spraying device with stable air flow and a use method, which significantly improves the paint adsorption rate, eliminates spraying dead angles to ensure uniform coating, and efficiently recovers oversprayed paint mist to reduce pollution. It is suitable for high-quality spraying of various complex geometric shape valve bodies, and solves the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A valve spraying device with stable air flow, comprising a conveyor belt for conveying a valve workpiece to be sprayed, a gantry is arranged transversely above the conveyor belt, a C-shaped mechanical arm is arranged in the middle of the gantry, and the open end of the C-shaped mechanical arm faces downward; a paint spraying device is arranged on the outer side of one end of the C-shaped mechanical arm, and a spray gun pipe connected with the paint spraying device is arranged on the inner side of the end of the C-shaped mechanical arm; a spray gun nozzle is arranged at the end of the spray gun pipe; after high-pressure air is input into the paint spraying device, the paint is crushed and atomized, and then sprayed out through the spray gun nozzle towards the orientation of the valve workpiece.

[0008] The inner wall of the other end of the C-shaped mechanical arm is provided with an airflow guide cover, the opening side of the airflow guide cover faces the valve workpiece direction, and the outer wall of the end of the C-shaped mechanical arm is further provided with a negative pressure fan in communication with the airflow guide cover.

[0009] The outer periphery of the spray gun nozzle is coaxially sleeved with an air curtain ring, the inside of the air curtain ring is a hollow structure and forms an annular air chamber; the inner periphery of the air curtain ring has an air outlet gap, the air outlet gap is formed by a staggered outer edge and an inner edge, the outer edge is connected to a curved air guide plate, and an air outlet channel with equal spacing is formed between the curved air guide plate and the inner edge, the opening of the air outlet channel faces the valve workpiece direction; the airflow flows in the annular air chamber and is sprayed out through the air outlet gap, and is sprayed out at high speed to the direction of the valve workpiece through the guidance of the air outlet channel, so that the air forms a circular cylindrical air curtain with stable speed and direction;

[0010] The left and right sides of the air curtain ring are symmetrically provided with a taper seat, the inside of the taper seat is a hollow structure and is in communication with the annular air chamber, and the inside of the taper seat is provided with a second driving motor, and the output end of the second driving motor is connected to an impeller in the inside of the taper seat.

[0011] Preferably, the outer periphery of the spray gun pipe is sleeved with a guide cylinder matched with the gap therebetween, the guide cylinder is connected to the spray gun pipe through buckling, the upper and lower sides of the taper seat and the air curtain ring are connected to the guide cylinder through connecting rods, and the air curtain ring is installed on the spray gun pipe through the guide cylinder and the connecting rods; the guide cylinder and the air curtain ring are coaxially distributed.

[0012] Preferably, the taper seat is connected to the air curtain ring at the narrower end, accommodates the second driving motor and the impeller at the wider end, and the outer wall of the taper seat is provided with an air inlet grille.

[0013] Preferably, the first driving motor is fixedly installed at the center of the top of the gantry, and the output end of the first driving motor penetrates downward through the gantry and is connected to the center position of the C-shaped mechanical arm.

[0014] Preferably, the airflow guide cover is horn-shaped, the flared end of the airflow guide cover faces the valve workpiece direction, and the suction port of the tail part is directly connected to the negative pressure fan through a short pipe.

[0015] Preferably, the axes of the spray gun pipe and the spray gun nozzle both extend in the horizontal direction, and the spray gun pipe and the spray gun nozzle are coaxially connected.

[0016] Preferably, the spray gun nozzle and the suction port of the airflow guide cover are coaxially distributed, and the center point of the valve workpiece is located at the midpoint of the axes of the spray gun nozzle and the suction port.

[0017] Preferably, the bottom ends of the paint spraying device, the spray gun pipe, the spray gun nozzle, the airflow guide cover, the negative pressure fan, the air curtain ring, and the taper seat are all higher than the bottom end of the C-shaped mechanical arm, and the bottom end of the C-shaped mechanical arm is higher than the surface of the conveying belt, so as to ensure rotation without interference.

[0018] A method for using an air-stable flow valve spraying device, based on an air-stable flow valve spraying device, comprising the following steps:

[0019] Step one, place the valve workpiece on the conveyor belt, and the conveyor belt will transport the valve workpiece to the spraying position below the gantry and then stop;

[0020] Step two, start the first drive motor to drive the C-shaped mechanical arm to rotate around the stationary valve workpiece;

[0021] Step three, start the paint spraying device, high-pressure air will crush and atomize the paint, then spray it to the surface of the valve workpiece through the spray gun pipe and the spray gun nozzle; at the same time, start the second drive motor to drive the impeller to rotate, air is sucked into the cone seat through the air inlet grid, pressurized and then flows into the annular air chamber, and is sprayed out at high speed through the air outlet gap and air outlet, forming a cylindrical air curtain that wraps the paint mist sprayed by the spray gun nozzle; at the same time, start the negative pressure fan to generate directional negative pressure at the suction port of the airflow guide cover, suck the oversprayed paint mist and stabilize the local airflow field;

[0022] Step four, after the C-shaped mechanical arm rotates one or more times to complete the spraying of the outer peripheral surface of the valve workpiece, the first drive motor, the paint spraying device, the second drive motor and the negative pressure fan are stopped, and the conveyor belt is started to move out the sprayed valve workpiece.

[0023] Compared with the prior art, the beneficial effects of the present application are:

[0024] 1. The present application sets a gas curtain ring structure coaxially outside the spray gun nozzle, the annular air chamber inside the structure is actively pressurized by the impeller in the two side cones, the airflow is sprayed out at high speed through the air outlet with a specific angle, forming a cylindrical laminar air curtain that wraps the paint mist, this physically isolated stable air curtain effectively resists external airflow disturbance, ensuring that the movement trajectory of paint particles from leaving the spray gun nozzle to reaching the surface of the valve workpiece remains linear and stable.

[0025] 2. The present application integrates the negative pressure recovery system and the spraying unit on the rotatable C-shaped mechanical arm. By setting the airflow guide cover and the negative pressure fan at the position exactly coaxial with the spray gun nozzle, and always forming a three-point-one-line symmetrical layout at the center point of the valve workpiece, a directional negative pressure field is established behind the spraying point, this design not only actively captures the oversprayed paint mist, but also actively constrains the spraying flow field through negative pressure airflow, eliminating vortex and turbulent flow.

[0026] 3. The present application performs spraying operation through the rotational movement of the C-shaped mechanical arm, the first drive motor at the top of the gantry drives the entire spraying device to rotate around the stationary valve workpiece, realizing no-dead-angle coverage of the complex valve body surface, combined with the operation of the conveying device, continuous spraying operation is also realized, without the need for operators or mechanical arms to pick up the valve workpiece to the designated spraying station one by one. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram showing the connection relationship of the air curtain rings of the present invention;

[0028] Figure 2 This is a diagram showing the relationship between the air curtain ring and the spray gun nozzle of the present invention;

[0029] Figure 3 Schematic diagram of the annular air chamber of the present invention;

[0030] Figure 4 A longitudinal cross-sectional view of the air curtain ring of the present invention;

[0031] Figure 5 This is a schematic cross-sectional view of an air curtain ring according to the present invention;

[0032] Figure 6 This is a schematic diagram of the air curtain ring air outlet of the present invention;

[0033] Figure 7 This is an axonometric view of the airflow guide cover of the present invention;

[0034] Figure 8 It is an axonometric view of the overall structure of the present invention;

[0035] Figure 9 It is a schematic plan view of the overall structure of the present invention.

[0036] In the figure: 1. Valve workpiece; 2. Conveyor belt; 3. Gantry; 4. First drive motor; 5. C-type robotic arm; 6. Paint spraying device; 7. Spray gun tube; 8. Spray gun nozzle; 9. Air flow guide cover; 10. Negative pressure fan; 11. Suction port; 12. Annular air chamber; 13. Air curtain ring; 14. Air outlet gap; 15. Curved air guide plate; 16. Outer edge; 17. Inner edge; 18. Air outlet duct; 19. Conical seat; 20. Impeller; 21. Second drive motor; 22. Air inlet grille; 23. Connecting rod; 24. Guide cylinder; 25. Positioning fixture. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] In order to solve the problem of turbulent airflow at the outlet of the existing spray gun and the resulting instability of the paint mist trajectory, please refer to Figures 1-9 , this embodiment provides the following technical solutions:

[0039] The valve workpiece 1 to be sprayed is placed on the positioning clamp 25 of the conveying belt 2, and is sent to the gantry 3 position in turn and intermittently at a preset beat. The gantry 3 spans above the conveying belt 2. The first driving motor 4 is arranged at the top center of the gantry 3. The output end of the first driving motor 4 is downwardly and penetrates through the gantry 3, and is connected with the C-shaped mechanical arm 5 below the gantry 3. The connection point is located at the center position of the C-shaped mechanical arm 5. The open end of the C-shaped mechanical arm 5 faces downward.

[0040] The outer side of one end of the C-shaped mechanical arm 5 is provided with a paint spraying device 6. The paint spraying device 6 is connected with the spray gun pipe 7 at the inner side of the end. The spray gun nozzle 8 is arranged at the end of the spray gun pipe 7. The axes of the spray gun pipe 7 and the spray gun nozzle 8 extend in the horizontal direction. After the high-pressure air is input into the paint spraying device 6, the paint is pulverized and atomized, and is sprayed to the position of the valve workpiece 1 through the spray gun nozzle 8.

[0041] The inner wall of the other end of the C-shaped mechanical arm 5 is provided with an airflow guide cover 9. The open side of the airflow guide cover 9 faces the position of the valve workpiece 1. The outer wall of the end is provided with a negative pressure fan 10. The airflow guide cover 9 is communicated with the negative pressure fan 10. A certain intensity of negative pressure is generated at the position opposite to the spraying point of the valve workpiece 1 through the airflow guide cover 9 and the negative pressure fan 10, so as to actively collect the oversprayed paint mist, thereby forming a stable and controllable airflow field in the local area. The spray gun nozzle 8 and the airflow guide cover 9 are coaxially distributed. The center point of the valve workpiece 1 is located at the midpoint of the axes of the spray gun nozzle 8 and the airflow guide cover 9, thereby forming a three-point-one-line airflow flow layout.

[0042] After the valve workpiece 1 reaches the spraying point, the conveying belt 2 stops. At this time, the first driving motor 4 is started, and drives the C-shaped mechanical arm 5 to rotate around the valve workpiece 1 for more than one turn to complete the full coverage spraying of the outer surface of the workpiece, thereby realizing the synchronous and uniform paint spraying coverage of the outer circumferential surface of the valve workpiece 1. At the same time of spraying, the negative pressure fan 10 is started, so that the suction port 11 of the airflow guide cover 9 generates directional airflow. The direction of the airflow is from the outer side of the valve workpiece 1 to the suction port 11 of the airflow guide cover 9, thereby forcibly guiding the flying paint mist to the suction port 11 for recycling treatment, greatly reducing the environmental pollution. At the same time, the directional suction airflow actually restricts the spraying airflow, so that it is more stably shot to the surface of the valve workpiece 1, thereby avoiding the generation of turbulent flow. In the process, the air curtain restricts the trajectory of the paint mist, and the negative pressure field suppresses the scattering of the airflow, so as to guarantee the stability of the spraying flow field.

[0043] The bottom end of the C-shaped mechanical arm 5 is higher than the surface of the conveying belt 2, and the bottom ends of the paint spraying device 6, the spray gun pipe 7, the airflow guide cover 9 and the negative pressure fan 10 are higher than the bottom end of the C-shaped mechanical arm 5, thereby ensuring that the C-shaped mechanical arm 5 does not collide with the conveying belt 2 when rotating. Generally, the clearance between the bottom of the C-shaped mechanical arm 5 and the surface of the conveying belt 2 is more than 50 mm, thereby ensuring that there is no interference in rotation.

[0044] In order to make the spray gun nozzle 8 spray flow stable to the valve workpiece 1 surface, a gas curtain ring 13 is arranged on the outer periphery of the spray gun nozzle 8, the gas curtain ring 13 is coaxially distributed with the spray gun nozzle 8, the inside of the gas curtain ring 13 is a hollow annular air chamber 12, the cross section of the gas curtain ring 13 is an open structure, the opening forms an air outlet gap 14, the air outlet gap 14 is located on the inner periphery of the gas curtain ring 13, the air outlet gap 14 is formed by the staggered outer edge 16 and the inner edge 17, the outer edge 16 is connected to the curved air guide plate 15, the curved air guide plate 15 and the inner edge 17 form air outlet channels 18 with equal spacing, the opening of the air outlet channel 18 is directed towards the valve workpiece 1.

[0045] The left and right sides of the gas curtain ring 13 are symmetrically provided with a cone seat 19, the inside of the cone seat 19 is a hollow structure and is in communication with the inner cavity of the gas curtain ring 13, the narrower end of the cone seat 19 is communicated with the gas curtain ring 13, the wider end of the inside of the cone seat 19 is provided with a second driving motor 21, the second driving motor 21 is connected to the impeller 20 towards the side of the gas curtain ring 13, and the outer wall of the cone seat 19 is provided with an air inlet grille 22 for sucking air.

[0046] Start the second driving motor 21 to drive the impeller 20 to rotate, suck air from the air inlet grille 22 into the cone seat 19 through the impeller 20, and form a gas flow towards the gas curtain ring 13, the gas flow is pressurized under the gradually narrowing action of the cone seat 19 and rushes into the annular air chamber 12, the gas flow flows in the annular air chamber 12 and is sprayed out through the air outlet gap 14, and is sprayed out at high speed towards the orientation of the valve workpiece 1 through the air outlet channel 18, so that the air forms a cylindrical air curtain with stable speed and direction, tightly wraps the paint mist beam sprayed out of the spray gun nozzle 8 in the center, and escorts it to the surface of the valve workpiece 1, this layer of air curtain can effectively resist the disturbance of external air, ensure that the paint particles are always wrapped and guided by the cylindrical air curtain after leaving the spray gun nozzle 8, ensure stable flow of the paint spraying gas, and ensure the spraying effect of the valve workpiece 1.

[0047] The gas curtain ring 13 is connected to the spray gun pipe 7 through a guide cylinder 24, the guide cylinder 24 is sleeved on the outer periphery of the spray gun pipe 7 and is in clearance fit with it, the guide cylinder 24 and the spray gun pipe 7 are connected by buckling, the upper and lower sides of the two cone seats 19 and the gas curtain ring 13 are connected to the guide cylinder 24 through connecting rods 23, and the guide cylinder 24 and the gas curtain ring 13 are coaxially distributed.

[0048] It should be noted that the paint spraying device 6, the spray gun tube 7 and the spray gun nozzle 8 combination, and the negative pressure fan 10 involved in the scheme are all mature components in the field of existing spraying and air treatment technology. The paint spraying device 6 represents a conventional spraying core unit, and the basic principle and working mode of pulverizing and atomizing paint by high-pressure air belong to the known technology; the spray gun tube 7 and the spray gun nozzle 8 connected therewith constitute a standard spray gun conveying and outlet structure, which is responsible for directing the atomized paint, and the design and function follow the general principle of industrial spray guns; similarly, the negative pressure fan 10 as the key equipment for generating negative pressure airflow in the scheme, the principle and implementation mode of sucking air and generating directional airflow are also widely used mature technology, which is commonly used in various industrial occasions requiring air collection or guidance. The innovativeness of the present scheme does not lie in the basic working principle of these independent units, but through the innovative integration and application of these mature technologies with specific mechanical structures and unique spatial layout, the specific technical problems such as airflow stability, precise guidance and recovery of paint mist in existing valve spraying are solved.

[0049] Working principle: the valve workpiece 1 to be sprayed is placed on the conveying belt 2 and conveyed to the designated spraying position under the gantry 3. When the valve workpiece 1 reaches the predetermined position, the conveying belt 2 stops running. At this time, the first driving motor 4 installed at the top of the gantry 3 is started to drive the C-shaped mechanical arm 5 below it to rotate around the stationary valve workpiece 1.

[0050] During the rotation, the paint spraying device 6 installed on one end of the outer side of the C-shaped mechanical arm 5 starts to work. High-pressure air pulverizes and atomizes paint, which is conveyed to the spray gun nozzle 8 through the spray gun tube 7, and the paint mist is sprayed to the surface of the valve workpiece 1. At the same time, in order to ensure the stability and directionality of the spraying airflow, the second driving motor 21 installed on the other end of the outer side of the C-shaped mechanical arm 5 is started. The second driving motor 21 drives the impeller 20 to rotate, and air is sucked into the cone seat 19 inside through the air inlet grille 22. The pressurized air flows into the annular air chamber 12 inside the air curtain ring 13 through the cone seat 19, and is finally sprayed out at high speed through the air outlet gap 14. The airflow is guided by the curved air deflector 15 and the air outlet 18 to form a stable and coaxial cylindrical air curtain that wraps the paint mist beam sprayed by the spray gun nozzle 8. The air curtain ring 13 is connected with the spray gun tube 7 through the guide cylinder 24, and its structure is stable by the connecting rod 23. This layer of air curtain effectively resists external interference and guides the paint mist beam to stably shoot towards the surface of the valve workpiece 1.

[0051] At the same time of spraying, the negative pressure fan 10 installed outside the other end of the C-shaped mechanical arm 5 is started. The negative pressure fan 10 communicates with the airflow guide cover 9 installed on the inner wall of the other end of the C-shaped mechanical arm 5, and generates directional negative pressure at the suction port 11 of the airflow guide cover 9. The suction port 11 is coaxially distributed with the spray gun nozzle 8, and the center point of the valve workpiece 1 is located at the position where the axes of the two coincide. The directional suction airflow forces the oversprayed and scattered paint mist to be directed to the suction port 11 for recovery, reducing environmental pollution, and stabilizes the local airflow field between the spray gun nozzle 8 and the valve workpiece 1, constrains the paint mist beam, avoids vortex and turbulence, and ensures uniform coating without dead angles.

[0052] The rotation of the C-shaped mechanical arm 5 realizes uniform spraying coverage of the entire outer surface of the valve workpiece 1 without any spraying dead angle. The installation positions of the paint spraying device 6, the spray gun pipe 7, the airflow guide cover 9, the negative pressure fan 10, the air curtain ring 13 and its attached components are all higher than the bottom end of the C-shaped mechanical arm 5, and the bottom end of the C-shaped mechanical arm 5 itself is also higher than the surface of the conveying belt 2, ensuring that there is no motion interference between the device and the conveying belt 2 during rotation.

[0053] It should be noted that, in the present text, relational terms such as first and second and the like can only be used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device.

[0054] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application.

Claims

1. A valve spraying device with stable air flow, comprising a gantry (3), characterized in that: The gantry (3) is provided with a C-shaped mechanical arm (5) with an opening facing downward, a paint spraying device (6) is installed on the outer side of one end of the C-shaped mechanical arm (5), a spray gun pipe (7) connected to the paint spraying device (6) is provided on the inner side of the end of the C-shaped mechanical arm (5), a spray gun nozzle (8) is provided on the spray gun pipe (7), and an air flow guide cover (9) is installed on the inner wall of the other end of the C-shaped mechanical arm (5), an air curtain ring (13) is coaxially sleeved on the outer periphery of the spray gun nozzle (8), and an annular air chamber (12) is provided in the air curtain ring (13); an air outlet gap (14) is provided on the inner peripheral surface of the air curtain ring (13), and the air outlet gap (14) is formed by a staggered outer edge (16) and an inner edge (17), the outer edge (16) is connected to a curved air guide plate (15), and an air outlet duct (18) is formed between the curved air guide plate (15) and the inner edge (17).

2. The valve spraying device with stable air flow according to claim 1, characterized in that: Conical seats (19) are provided on both sides of the air curtain ring (13), a second drive motor (21) is provided in the conical seat (19), the second drive motor (21) is connected to the impeller (20), and the inner cavity of the conical seat (19) is communicated with the annular air chamber (12).

3. The valve spraying device with stable air flow according to claim 2, characterized in that: The outer circumference of the spray gun tube (7) is sleeved with a guide cylinder (24) that is clearance-matched therewith. The guide cylinder (24) is connected to the spray gun tube (7) through a buckle. The upper and lower sides of the cone seat (19) and the air curtain ring (13) are connected to the guide cylinder (24) through connecting rods (23) respectively. The air curtain ring (13) is installed on the spray gun tube (7) through the guide cylinder (24) and the connecting rod (23); the guide cylinder (24) and the air curtain ring (13) are coaxially distributed.

4. The valve spraying device with stable air flow according to claim 3, characterized in that: The narrower end of the cone seat (19) is connected to the air curtain ring (13), and the wider end accommodates the second drive motor (21) and the impeller (20). The outer wall of the cone seat (19) is provided with an air inlet grille (22).

5. The valve spraying device with stable air flow according to claim 1, characterized in that: A first drive motor (4) is fixedly mounted in the center of the top of the gantry (3), and an output end of the first drive motor (4) passes downward through the gantry (3) and is connected to the center of the C-shaped mechanical arm (5).

6. The valve spraying device with stable air flow according to claim 1, characterized in that: A negative pressure fan (10) is installed on the outer wall of the end of the C-shaped mechanical arm (5), and the negative pressure fan (10) is connected to the air flow guide cover (9); the air flow guide cover (9) is trumpet-shaped, and its expanded end faces the valve workpiece (1), and the suction port (11) at the tail is directly connected to the negative pressure fan (10) through a short pipe.

7. The valve spraying device with stable air flow according to claim 1, characterized in that: The axes of the spray gun pipe (7) and the spray gun nozzle (8) both extend in the horizontal direction, and the spray gun pipe (7) and the spray gun nozzle (8) are coaxially connected.

8. The valve spraying device with stable air flow according to claim 1, characterized in that: The spray gun nozzle (8) and the suction port (11) of the air flow guide cover (9) are coaxially distributed, and the center point of the valve workpiece (1) is located at the midpoint of the axis of the spray gun nozzle (8) and the suction port (11).

9. The valve spraying device with stable air flow according to claim 6, characterized in that: The bottom ends of the paint spraying device (6), the spray gun tube (7), the spray gun nozzle (8), the air flow guide cover (9), the negative pressure fan (10), the air curtain ring (13), and the cone seat (19) are all higher than the bottom end of the C-shaped mechanical arm (5), and the bottom end of the C-shaped mechanical arm (5) is higher than the surface of the conveyor belt (2).

10. A method for using a valve spraying device with stable air flow, which is implemented based on the valve spraying device with stable air flow according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Place the valve workpiece (1) on the conveyor belt (2), and the conveyor belt (2) transports the valve workpiece (1) to the spraying position below the gantry (3) and then stops; Step 2: Start the first drive motor (4) to drive the C-shaped mechanical arm (5) to rotate around the stationary valve workpiece (1); Step 3: Start the paint spraying device (6), and the high-pressure air crushes and atomizes the paint and sprays it onto the surface of the valve workpiece (1) through the spray gun tube (7) and the spray gun nozzle (8); at the same time, start the second drive motor (21) to drive the impeller (20) to rotate, and the air is sucked into the cone seat (19) through the air inlet grille (22), and after being pressurized, it flows into the annular air chamber (12), and is ejected at high speed through the air outlet gap (14) and the air outlet duct (18), forming a cylindrical air curtain that wraps the paint mist sprayed by the spray gun nozzle (8); at the same time, start the negative pressure fan (10) to generate a directional negative pressure at the suction port (11) of the air flow guide cover (9), sucking in the oversprayed paint mist and stabilizing the local air flow field; Step 4: After the C-shaped robotic arm (5) rotates one or more times to complete the spraying of the outer surface of the valve workpiece (1), the first drive motor (4), the paint spraying device (6), the second drive motor (21), and the negative pressure blower (10) are stopped, and the conveyor belt (2) is started to remove the sprayed valve workpiece (1).

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