A vertical spray booth and a spraying method thereof

Abstract

The application discloses a vertical spraying room and a spraying method applied to the vertical spraying room. The vertical spraying room comprises a room body, a spraying machine and an air exhaust device. The room body is provided with a spraying cavity, the spraying machine is provided with a spraying gun, the spraying gun is arranged in the spraying cavity, the spraying machine is configured to drive the spraying gun to move up and down, the spraying gun is configured to be transversely sprayed, and the air exhaust device can suck the spraying cavity. An air suction opening is arranged on the side wall of the spraying cavity opposite to the spraying outlet of the spraying gun, the air suction opening is vertically arranged, and the air exhaust device sucks the spraying cavity through the air suction opening. The vertical spraying room has good air suction effect.

Description

Technical Field

[0001] This invention relates to the field of spraying, and particularly to a vertical spray booth and its spraying method. Background Technology

[0002] A vertical spray booth is currently available, comprising a booth body, a spraying machine, and an exhaust system. The booth body has a spraying chamber, and the spraying machine has a spray gun that extends into the spraying chamber and can move up and down, thereby allowing vertical spraying of workpieces entering the booth. The exhaust system is used to extract air containing dispersed color powder from the booth to recover the color powder and purify the air. However, in the existing vertical spray booth, the extraction effect of the exhaust system when drawing air from the spraying chamber is still insufficient and cannot meet higher requirements. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a vertical spray booth that can improve the suction effect of the exhaust device.

[0004] The present invention also proposes a spraying method applicable to the above-mentioned vertical spray booth.

[0005] According to a first aspect of the present invention, a vertical spray booth includes: a booth body having a spray chamber; a spraying machine having a spray gun disposed in the spray chamber, the spraying machine being configured to drive the spray gun to move up and down, the spray gun being configured to spray horizontally; and an exhaust device capable of suctioning the spray chamber; wherein, a suction opening is provided on the side wall of the spray chamber opposite to the nozzle of the spray gun, the suction opening being vertically arranged, and the exhaust device suctioning the spray chamber through the suction opening.

[0006] According to a first aspect of the present invention, a vertical spray booth has at least the following advantages: In the vertical spray booth, the vertically arranged suction opening is located on the side wall directly opposite the nozzle of the spray gun, and the spray gun is a horizontal spray gun that moves up and down. Thus, during the spraying process, after the color powder sprayed by the spray gun has colored the workpiece, the excess color powder can be more directly and quickly sucked away by the suction opening on the opposite side, resulting in a good suction effect.

[0007] According to some embodiments of the present invention, the spray guns of the spraying machine are arranged in a row along the front-to-back direction, and at least two corresponding suction openings are arranged along the front-to-back direction. The suction openings are located at both ends of the row of spray guns along the arrangement direction.

[0008] According to some embodiments of the present invention, two spraying machines are provided and located on the left and right sides of the chamber respectively. The spray guns of the two spraying machines are opposite to each other and spray in opposite directions. A workpiece spraying area is provided between the spray guns of the two spraying machines. Two sets of suction openings are provided, and the two sets of suction openings are located on the left and right sidewalls of the spraying chamber respectively and correspond one-to-one with the two spraying machines.

[0009] According to some embodiments of the present invention, the exhaust device includes a pipe group corresponding one-to-one with the suction opening. The pipe group includes a first exhaust pipe, a second exhaust pipe, and a connecting pipe. The first exhaust pipe and the second exhaust pipe are arranged vertically side by side. The first exhaust pipe is provided with a connecting port, which is arranged vertically. The first exhaust pipe is connected to the suction opening through the connecting port. Multiple connecting pipes are provided and arranged vertically. The two ends of the connecting pipes are respectively connected to the first exhaust pipe and the second exhaust pipe. The connecting pipe is provided with a control valve to control the on / off state of the connecting pipe. The exhaust device also includes a main suction pipe for providing suction negative pressure, which is connected to the second exhaust pipe. The vertical spray booth also includes a control device configured to control the spray gun action of the spraying machine and to control the on / off state of the control valve.

[0010] According to some embodiments of the present invention, the chamber is provided with a bottom suction cavity, the bottom suction cavity is disposed around the bottom of the spraying cavity, the bottom suction cavity has an opening around the bottom of the spraying cavity on the side near the spraying cavity, the exhaust device is configured to suction the bottom suction cavity, and an air jet is provided at the bottom of the spraying cavity, the air jet being used to form an airflow blowing toward the opening of the bottom suction cavity.

[0011] According to some embodiments of the present invention, the upper and lower parts of the room are provided with door openings, the room is provided with a cleaning door for closing or opening the door openings, and the room is provided with a maintenance ladder for operators to access the cleaning door at the upper part of the room.

[0012] According to some embodiments of the present invention, the exhaust device is equipped with a cyclone separator and a filter unit.

[0013] According to some embodiments of the present invention, the chamber is provided with a workpiece inlet and a workpiece outlet, the workpiece inlet and the workpiece outlet are connected to the spraying cavity, and the chamber is provided with an inlet door and an outlet door, the inlet door being used to close or open the workpiece inlet, and the outlet door being used to close or open the workpiece outlet.

[0014] According to a second aspect of the present invention, a spraying method includes the following steps: during spraying, based on the position height of the spray gun, in the pipe group further corresponding to the suction opening corresponding to the spray gun, the control valve of the connecting pipe closest to the spray gun is opened, while the control valves of the remaining connecting pipes in the pipe group are closed.

[0015] According to the second aspect of the present invention, the spraying method has at least the following advantages: on the one hand, since the vertical spray booth of the first aspect of the present invention is used for spraying, it has the characteristic of good pigment suction effect; on the other hand, since the connecting pipes at similar heights are selectively opened according to the height position of the spray gun, the suction pressure at the corresponding height of the suction opening is maximized, thereby concentrating the suction pressure to suction the area where the spraying operation is being carried out near that height, resulting in good suction effect and energy saving.

[0016] According to some embodiments of the present invention, during spraying, the spray guns of the two spraying machines are sprayed at staggered positions.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0019] Figure 1 This is a three-dimensional schematic diagram of an embodiment of the present invention;

[0020] Figure 2 for Figure 1 A cross-sectional view of the structure shown;

[0021] Figure 3 for Figure 2 Enlarged view of point B;

[0022] Figure 4 for Figure 1 CC cross-sectional view of the structure shown;

[0023] Figure 5 This is a three-dimensional schematic diagram of the bottom structure of the room body according to an embodiment of the present invention;

[0024] Figure 6 for Figure 4 Enlarged diagram of point D;

[0025] Figure 7 for Figure 1 A magnified view of a portion of the structure shown.

[0026] Figure label:

[0027] Chamber body 100, spraying chamber 110, suction opening 120, bottom suction chamber 130, connecting opening 131, jetting component 140, cleaning door 150, maintenance ladder 160, workpiece inlet 171, workpiece outlet 172, inlet door 181, outlet door 182, inlet side air guide plate 191, outlet side air guide plate 192.

[0028] 200 spray painting machine, 210 spray gun;

[0029] Exhaust device 300, duct assembly 310, first exhaust duct 311, connecting port 3111, second exhaust duct 312, connecting duct 313, control valve 3131, main suction pipe 320, auxiliary suction pipe 330, cyclone separator 340, filter unit 350. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0032] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0033] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0034] Reference Figures 1 to 7A vertical spray booth includes a booth body 100, a sprayer 200, and an exhaust system 300. The booth body 100 has a spraying chamber 110, and the sprayer 200 has a spray gun 210 positioned within the spraying chamber 110. The sprayer 200 is configured to drive the spray gun 210 to move vertically, and the spray gun 210 is configured for horizontal spraying. The exhaust system 300 draws air from the spraying chamber 110. A suction opening 120 is provided on the side wall of the spraying chamber 110 opposite the nozzle of the spray gun 210. The suction opening 120 is vertically arranged, and the exhaust system 300 draws air from the spraying chamber 110 through the suction opening 120. It is understood that the vertical arrangement of the suction opening 120 means that the suction opening 120 is vertically extended or multiple openings arranged in a vertical row. It is understood that in this article, "horizontal" refers to the horizontal direction or a direction slightly inclined to the horizontal direction (inclination angle less than 45°).

[0035] In the aforementioned vertical spray booth, the vertically arranged suction opening 120 is located on the side wall directly opposite the nozzle of the spray gun 210. The spray gun 210 is a horizontal spray gun that moves up and down. Thus, during the spraying process, after the color powder sprayed by the spray gun 210 has colored the workpiece, the excess color powder can be more directly and quickly sucked away by the suction opening 120 on the opposite side, resulting in a good suction effect.

[0036] In this embodiment, the spraying machine 200 may specifically be equipped with a vertical linear movement module. By placing the spray gun 210 on this linear movement module, the vertical movement of the spray gun 210 can be achieved. The linear movement module may specifically employ a linear motor, a lead screw motor module, etc. It is conceivable that the spraying machine 200 may also achieve the vertical movement of the spray gun 210 by incorporating some lifting mechanisms. It is understood that there are many implementation methods in the art for realizing the movement of components along a predetermined direction, and those skilled in the art can configure them according to actual conditions.

[0037] In this embodiment, the spray guns 210 of the spraying machine 200 are arranged in a row along the front-to-back direction, and at least two corresponding suction openings 120 are arranged along the front-to-back direction. Each end of the row of spray guns 210 has a corresponding suction opening 120 along its arrangement direction. With this structure, the toner suction effect is better for the row of spray guns 210.

[0038] In this embodiment, two sprayers 200 are provided, located on the left and right sides of the chamber 100 respectively. The spray guns 210 of the two sprayers 200 are facing each other and spray in opposite directions. A workpiece spraying area is provided between the spray guns 210 of the two sprayers 200. Two sets of suction openings 120 are provided, located on the left and right sidewalls of the spraying chamber 110 respectively and corresponding to the two sprayers 200. With the above structure, the workpiece can be sprayed on both sides by the spray guns 210 of the two sprayers 200 in the workpiece spraying area, resulting in high spraying efficiency. At the same time, the two sets of suction openings 120 are provided to respectively suction the spray guns 210 of the two sprayers 200, thereby ensuring the suction efficiency of the pigment.

[0039] Specifically, in this embodiment, each group of suction openings 120 has two suction openings 120. It is conceivable that other numbers can be selected according to the actual situation, such as one or more than two. In this embodiment, the spray guns 210 of the two sprayers 200 are located on the left and right sides of the spraying chamber 110, with the left spray gun 210 spraying to the right and the right spray gun 210 spraying to the left.

[0040] In an embodiment, the exhaust device 300 includes pipe groups 310 corresponding one-to-one with the suction openings 120. Each pipe group 310 includes a first exhaust pipe 311, a second exhaust pipe 312, and connecting pipes 313. The first exhaust pipe 311 and the second exhaust pipe 312 are arranged vertically side-by-side. The first exhaust pipe 311 has a connecting port 3111, which is vertically arranged and connects to the suction openings 120 through the connecting port 3111. Multiple connecting pipes 313 are provided and arranged vertically. Between the first exhaust duct 311 and the second exhaust duct 312, the two ends of a connecting pipe 313 are respectively connected to the first exhaust duct 311 and the second exhaust duct 312. The connecting pipe 313 is equipped with a control valve 3131 to control the on / off state of the connecting pipe 313. The exhaust device 300 also includes a main suction pipe 320 for providing suction negative pressure, which is connected to the second exhaust duct 312. The vertical spray booth also includes a control device configured to control the action of the spray gun 210 of the sprayer 200 and to control the on / off state of the control valve 3131. It can be understood that the vertical arrangement of the connecting port 3111 mentioned above refers to the vertical extension or multiple connecting ports 3111 arranged vertically.

[0041] During spraying, while controlling the up-and-down movement of the spray gun 210 of the spraying machine 200, the control device also controls the control valve 3131 according to the height position of the spray gun 210. Only the control valve 3131 of the connecting pipe 313 closest to that height is opened (the others are closed), so that the suction force of the connecting port 3111 and the suction opening 120 is maximized at the height position of the opened connecting pipe 313 (there is also suction force at other height positions, but the suction pressure is relatively small). This allows the suction pressure to be concentrated to suction the height area being sprayed, resulting in good suction effect and energy saving.

[0042] In this embodiment, the control valve 3131 may specifically adopt the structure of a butterfly valve, a solenoid valve, etc. The control device may specifically adopt industrial control equipment such as an industrial control computer or a PLC, and be electrically connected to the spray painting machine 200 and the control valve 3131 to control the operation of the spray painting machine 200 and the control valve 3131.

[0043] In this embodiment, the chamber 100 is provided with a bottom suction cavity 130, which surrounds the bottom of the spraying cavity 110. The bottom suction cavity 130 has an opening surrounding the bottom of the spraying cavity 110 on the side closest to the spraying cavity 110. The exhaust device 300 is configured to suction the bottom suction cavity 130. An air jet 140 is provided at the bottom of the spraying cavity 110 to generate an airflow towards the opening of the bottom suction cavity 130. During the spraying process, pigment powder that is not sucked by the suction opening 120 and settles downwards can be blown into the bottom suction cavity 130 by the air jet 140. Simultaneously, the bottom suction cavity 130 is also sucked by the exhaust device 300. This ensures that the settled pigment powder is effectively removed by the exhaust device 300, reducing pigment powder accumulation at the bottom of the bottom suction cavity 130 and simplifying subsequent cleaning.

[0044] In an embodiment, the exhaust device 300 includes a secondary suction pipe 330. The bottom wall of the bottom suction chamber 130 is provided with a communication opening 131 that communicates with the secondary suction pipe 330. The secondary suction pipe 330 is connected to the main suction pipe 320, so that the exhaust device 300 can suck the bottom suction chamber 130 through the secondary suction pipe 330.

[0045] In this embodiment, the jetting element 140 is elongated and disposed on the bottom wall of the spraying cavity 110. The jetting element 140 is arranged along the front-to-back direction and divides the bottom wall of the spraying cavity 110 into a left half and a right half. Jet nozzles are respectively provided on the left and right sides of the jetting element 140, with the jet nozzle on the left side facing left and the jet nozzle on the right side facing right. With the above structure, the jet nozzle on the left side of the jetting element 140 is responsible for blowing away the pigment powder at the bottom of the left half of the spraying cavity 110, and the jet nozzle on the right side of the jetting element 140 is responsible for blowing away the pigment powder at the bottom of the right half of the spraying cavity 110. This allows for a more comprehensive blowing away of the pigment powder that has settled at the bottom of the spraying cavity 110, resulting in a smaller blind spot during cleaning.

[0046] In one embodiment, the jet component 140 has an air intake channel inside, and each jet nozzle is connected to the air intake channel. By introducing compressed gas into the air intake channel, cleaning gas can be ejected from the jet nozzles. The jet component 140 can also adopt a component structure, by setting two rows of air nozzles facing left and right respectively on the front and rear extended frame, and each air nozzle is connected to the air intake pipe through an air pipe, thereby also realizing the function of jetting to the left and right.

[0047] In this embodiment, the room 100 has door openings at both its upper and lower parts. The room 100 is equipped with a cleaning door 150 for closing or opening these openings, and a maintenance ladder 160 for operators to access the cleaning door 150 at the upper part of the room 100. The cleaning door 150 can be used for observation and subsequent cleaning, while the maintenance ladder 160 facilitates operation.

[0048] In this embodiment, the main suction pipe 320 of the exhaust device 300 is connected to the second exhaust pipe 312 and the auxiliary suction pipe 330 of each pipe group 310. The main suction pipe 320 is used to provide negative pressure for suction. Specifically, the exhaust device 300 can achieve suction by setting a fan structure to suction the main suction pipe 320, or the exhaust device 300 can be provided with a docking pipe that can be connected to an external fan to connect to the main suction pipe 320, so that the main suction pipe 320 can provide negative pressure for suction.

[0049] In this embodiment, the exhaust device 300 is equipped with a cyclone separator 340 and a filter unit 350. The cyclone separator 340 can be used to separate and recover color powder, and the filter unit 350 can be used to filter the exhaust airflow.

[0050] In this embodiment, the spray booth 100 is provided with a workpiece inlet 171 and a workpiece outlet 172, which are connected to the spraying chamber 110. The spray booth 100 is also provided with an inlet door 181 and an outlet door 182. The inlet door 181 is used to close or open the workpiece inlet 171, and the outlet door 182 is used to close or open the workpiece outlet 172. Workpieces can enter the spraying chamber 110 through the workpiece inlet 171 via a hoisting mechanism and exit through the workpiece outlet 172 after spraying. During normal spraying, the inlet door 181 and outlet door 182 can be opened to allow external airflow. When cleaning the spray booth, the inlet door 181 and outlet door 182 can be closed to reduce pigment leakage during subsequent cleaning.

[0051] In this embodiment, the chamber 100 is provided with an inlet-side air guide plate 191 and an outlet-side air guide plate 192. The inlet-side air guide plate 191 and the opened inlet door 181 are vertically arranged and parallel to each other, located on both sides of the workpiece inlet 171. Similarly, the outlet-side air guide plate 192 and the opened outlet door 182 are vertically arranged and parallel to each other, located on both sides of the workpiece outlet 172. When opened, air ducts can be formed between the inlet door 181 and the inlet-side air guide plate 191, and between the outlet door 182 and the outlet-side air guide plate 192, guiding airflow into the spraying chamber 110 and ensuring smooth airflow. In this embodiment, one side of the inlet door 181 and the outlet door 182 is pivotally connected to the main body of the chamber 100, allowing them to be rotated open and closed.

[0052] This invention also provides a spraying method applied to the aforementioned vertical spray booth. The spraying method specifically includes the following steps: During spraying, based on the height of the spray gun 210, in the pipe group 310 further corresponding to the suction opening 120 of the spray gun 210, the control valve 3131 of the connecting pipe 313 closest to the spray gun 210 is opened, while the control valves 3131 of the remaining connecting pipes 313 in the pipe group 310 are closed. Using this spraying method, the suction pressure can be concentrated to focus on the height area where the spraying operation is taking place, resulting in better suction and energy savings.

[0053] In this embodiment, during spraying, the spray guns 210 of the two sprayers 200 are sprayed at staggered positions to avoid excessively high pigment concentration at the same height position and to avoid mutual interference between the two sets of suction openings 120 on opposite sides.

[0054] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A vertical spray booth, characterized in that, include: The chamber (100) is equipped with a spraying cavity (110). A spraying machine (200) is provided with a spray gun (210), the spray gun (210) is disposed in the spraying chamber (110), the spraying machine (200) is configured to drive the spray gun (210) to move up and down, and the spray gun (210) is configured to spray horizontally; The exhaust device (300) is capable of sucking up the spraying chamber (110); The spraying chamber (110) has a suction opening (120) on the side wall opposite to the nozzle of the spray gun (210). The suction opening (120) is vertically arranged, and the exhaust device (300) draws air from the spraying chamber (110) through the suction opening (120). The exhaust device (300) includes a pipe group (310) corresponding to each suction opening (120). The pipe group (310) includes a first exhaust pipe (311), a second exhaust pipe (312), and a connecting pipe (313). The first exhaust pipe (311) and the second exhaust pipe (312) are arranged vertically side by side. The first exhaust pipe (311) is provided with a connecting port (3111). The connecting port (3111) is vertically arranged. 311) The connection port (3111) is connected to the suction opening (120). Multiple connecting pipes (313) are provided and arranged vertically. The two ends of the connecting pipes (313) are connected to the first exhaust pipe (311) and the second exhaust pipe (312) respectively. The connecting pipes (313) are provided with control valves (3131) to control the opening and closing of the connecting pipes (313). The exhaust device (300) also includes a main suction pipe (320) for providing suction negative pressure. The main suction pipe (320) is connected to the second exhaust pipe (312). The vertical spray booth also includes a control device. The control device is configured to control the action of the spray gun (210) of the spraying machine (200) and to control the opening and closing of the control valve (3131).

2. The vertical spray booth according to claim 1, characterized in that: The spray guns (210) of the spraying machine (200) are arranged in a row along the front-to-back direction, and at least two corresponding suction openings (120) are arranged along the front-to-back direction. The two ends of the row of spray guns (210) along the arrangement direction are respectively provided with suction openings (120).

3. A vertical spray booth according to claim 1 or 2, characterized in that: Two sprayers (200) are provided and located on the left and right sides of the chamber (100) respectively. The spray guns (210) of the two sprayers (200) are opposite to each other and spray in opposite directions. A workpiece spraying area is provided between the spray guns (210) of the two sprayers (200). Two sets of suction openings (120) are provided. The two sets of suction openings (120) are located on the left and right side walls of the spraying chamber (110) respectively and correspond one-to-one with the two sprayers (200).

4. A vertical spray booth according to claim 1, characterized in that: The chamber (100) is provided with a bottom suction cavity (130), which is arranged around the bottom of the spraying cavity (110). The bottom suction cavity (130) has an opening around the bottom of the spraying cavity (110) on the side near the spraying cavity (110). The exhaust device (300) is configured to suck the bottom suction cavity (130). The bottom of the spraying cavity (110) is provided with an air jet (140), which is used to form an airflow blowing toward the opening of the bottom suction cavity (130).

5. A vertical spray booth according to claim 1, characterized in that: The upper and lower parts of the room (100) are provided with door openings. The room (100) is provided with a cleaning door (150) for closing or opening the door openings. The room (100) is provided with a maintenance ladder (160) for operators to reach the cleaning door (150) at the upper part of the room (100).

6. A vertical spray booth according to claim 1, characterized in that: The exhaust device (300) is equipped with a cyclone separator (340) and a filter unit (350).

7. A vertical spray booth according to claim 1, characterized in that: The chamber (100) is provided with a workpiece inlet (171) and a workpiece outlet (172), which are connected to the spraying chamber (110). The chamber (100) is provided with a feed door (181) and a discharge door (182), which are used to close or open the workpiece inlet (171) and the discharge door (182) are used to close or open the workpiece outlet (172).

8. A spraying method, applied to the vertical spray booth as described in claim 1, characterized in that, The process includes the following steps: During spraying, based on the height of the spray gun (210), the control valve (3131) of the connecting pipe (313) closest to the spray gun (210) in the pipe group (310) further corresponding to the suction opening (120) of the spray gun (210) is opened, while the control valves (3131) of the remaining connecting pipes (313) in the pipe group (310) are closed.

9. A spraying method according to claim 8, characterized in that: Two sprayers (200) are provided and located on the left and right sides of the chamber (100) respectively. The spray guns (210) of the two sprayers (200) are opposite to each other and spray in opposite directions. A workpiece spraying area is provided between the spray guns (210) of the two sprayers (200). Two sets of suction openings (120) are provided. The two sets of suction openings (120) are located on the left and right side walls of the spraying chamber (110) respectively and correspond one-to-one with the two sprayers (200). During spraying, the spray guns (210) of the two sprayers (200) are sprayed at staggered positions.

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