Vehicle Paint Sprayer

Abstract

To provide a vehicle sprayer capable of improving the cleaning performance of pipes in an inkjet type paint head even under low pressure. [Solution] The vehicle sprayer includes a supply path 32 that supplies paint to an inkjet type paint head 31, a bypass flow path 33 that causes the paint in the supply path 32 to bypass the paint head 31, a switching unit 35 that switches the paint from the supply path 32 between head flow paths 31a, 31b and the bypass flow path 33, a supply unit 36 ​​that selectively supplies cleaning liquid and air to the supply path 32, and a cleaning control unit 37 that controls the switching unit 35 and the supply unit 36 ​​to clean the paint head 31, and the cleaning control unit 37 supplies air when the supply path 32 is in a supply state to the bypass flow path 33 and the supply path 32 is filled with cleaning liquid, and when the air and cleaning liquid form two layers along the flow direction, the first three-way valve 35 is switched to the head flow paths 31a, 31b side to flow the cleaning liquid, thereby cleaning the paint head 31 with the cleaning liquid in a gas-liquid mixed state.

Description

Technical Field

[0001] The present invention relates to a vehicle painting machine.

Background Art

[0002] A painting machine that paints the body of an automobile (hereinafter simply referred to as the body) using inkjet technology is known. An inkjet-type vehicle painting machine includes a painting head that discharges a predetermined amount of paint droplets toward the body from each of a plurality of nozzles provided on a nozzle forming surface (discharge surface).

[0003] Patent Document 1 discloses that in an inkjet-type vehicle painting machine, a cleaning operation is performed by flowing a cleaning liquid through the painting head. In order to improve the cleanability of the painting head, a method of using a cleaning liquid mixed with high-pressure compressed air or a method of using a cleaning liquid containing microbubbles generated at high pressure can be considered.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the painting head in an inkjet-type vehicle painting machine has a low pressure resistance value in terms of structure, a method of performing cleaning under high pressure cannot be adopted.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a vehicle painting machine capable of improving the cleanability of the pipelines inside an inkjet-type painting head even under low pressure.

Means for Solving the Problems

[0007] A vehicle painting machine according to one aspect of the present invention includes an inkjet painting head having a plurality of nozzles for discharging paint and a head flow path for supplying paint to the nozzles, a supply path for supplying paint toward the painting head, a bypass flow path for flowing the paint in the supply path to the downstream side of the painting head bypassing the painting head, a switching unit for switching the supply state of the paint from the supply path between the head flow path and the bypass flow path, a supply unit for selectively supplying a cleaning liquid and air to the supply path, and a cleaning control unit for controlling the switching unit and the supply unit to clean the painting head. The cleaning control unit supplies air in a state where the switching unit is switched to the supply state to the bypass flow path and the supply path is filled with the cleaning liquid, and in a state where the air and the cleaning liquid are in two layers along the flow direction, switches the switching unit to the supply state to the head flow path and flows the cleaning liquid to the head flow path to clean the painting head with the cleaning liquid in a gas-liquid mixed state.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a vehicle painting machine capable of improving the cleanability of the pipelines in an inkjet painting head even under low pressure.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0010] Hereinafter, the vehicle painting machine 10 according to the present embodiment will be described with reference to the drawings.

[0011] FIG. 1 is a schematic configuration diagram showing a painting robot 11 of the vehicle painting machine 10 according to the present embodiment. The painting robot 11 is arranged near the painting line in an automobile manufacturing factory and paints the vehicle body FR conveyed along the painting line. In the present embodiment, the vehicle body FR of an automobile is exemplified as the object to be painted, but it may be other than the vehicle body FR of an automobile.

[0012] [Painting Robot] The painting robot 11 paints the vehicle body FR conveyed from the upstream side of the painting line. The painting process may be performed by painting the vehicle body FR while flowing the painting line, or may be performed by stopping the flow of the line at a predetermined position and painting. The vehicle body FR painted by the painting robot 11 is conveyed toward the downstream side of the painting line.

[0013] In the present embodiment, the painting robot 11 is exemplified as the device for painting the vehicle body FR, but any device having the paint circulation path 30 described later may be used instead of the painting robot 11. Further, the painting robot 11 is exemplified as one in which the painting head unit 24 can rotate in directions centered on three axes of the X axis, Y axis, and Z axis, but the painting head unit 24 may rotate around any one of the X axis, Y axis, or Z axis, or may rotate around two axes.

[0014] Painting is performed for the purpose of forming a paint film on the surface of the object to be painted and providing protection and aesthetics to the surface. The painting process may include only painting with a paint of a specific color or a paint having a specific function, or may include sequentially applying paints of multiple colors or paints having a specific function.

[0015] The painting robot 11 exemplifies an articulated robot, but a scalar robot may also be used as long as it can perform painting. As shown in FIG. 1, the painting robot 11 includes a base 20, legs 21, a rotational drive unit 22, a robot arm 23, and a painting head unit 24.

[0016] The base 20 is a fixing member that fixes the painting robot 11 to the floor surface of the painting line and supports the painting robot 11. The base 20 may be movable on the floor surface of the painting line.

[0017] The legs 21 have a lower portion fixed to the base 20, an upper portion connected to the rotational drive unit 22, and extend to a vertical height suitable for performing painting by the painting robot 11.

[0018] The rotational drive unit 22 is connected to the upper end of the legs 21 and has a rotating shaft portion 25 and a rotating arm 26. The rotating shaft portion 25 rotates the rotating arm 26 about an axis parallel to the floor surface (the X-axis direction shown in FIG. 1) by a motor (not shown). The rotating arm 26 rotates the robot arm 23 connected to the rotating arm 26 about a straight line orthogonal to the rotation center of the rotating shaft portion 25 (the Z-axis direction shown in FIG. 1).

[0019] The robot arm 23 has a first rotating arm 27 and a second rotating arm 28. One end of the first rotating arm 27 is connected to the rotating arm 26, and the other end is connected to the second rotating arm 28. The first rotating arm 27 rotates about the Z-axis direction shown in FIG. 1 by a motor (not shown) mounted on the rotating arm 26. One end of the second rotating arm 28 is connected to the first rotating arm 27, and the other end has a wrist portion 29 described later. The second rotating arm 28 rotates about the Z-axis direction shown in FIG. 1 by a motor (not shown).

[0020] The painting head unit 24 is arranged at the most distal end side of the painting robot 11 and sprays paint onto the vehicle body FR of the automobile. A list part 29 is held between the painting head unit 24 and the second rotating arm 28. The list part 29 rotates the painting head unit 24 around at least one of the three axes (X-axis, Y-axis, and Z-axis) shown in FIG. 1.

[0021] The painting head unit 24 has a paint circulation path 30 inside for spraying paint from the painting head, and sprays paint onto the vehicle body FR flowing on the painting line at an appropriate timing.

[0022] [Paint circulation path] Next, the paint circulation path 30 of the vehicle painting machine 10 will be described with reference to FIG. 2. FIG. 2 is a circuit diagram showing a part of the paint circulation path 30 of the vehicle painting machine 10 according to the present embodiment.

[0023] The paint circulation path 30 includes a painting head 31, a supply path 32, a bypass flow path 33, a return flow path 34, a first three-way valve 35, a supply valve 36, and a cleaning control unit 37.

[0024] When painting the vehicle body FR, the paint circulation path 30 supplies the paint stored in a paint tank (not shown) to the painting head 31 via the supply path 32, and returns the paint not used by the painting head 31 to the paint tank via the return flow path 34. It is a circulation circuit. Further, when not painting the vehicle body FR, the paint circulation path 30 also functions as a circulation circuit that returns the paint stored in the paint tank from the supply path 32, via the bypass flow path 33, and via the return flow path 34 to the paint tank.

[0025] Here, in the supply path 32, the paint supply direction refers to the paint tank side as the upstream side and the painting head 31 side as the downstream side. Also, in the return flow path 34, the painting head 31 side is referred to as the upstream side and the paint tank side is referred to as the downstream side.

[0026] The paint is an aqueous paint or a solvent-based paint using pigments. Therefore, by circulating the paint within the paint circulation path 30, it is possible to prevent the pigments contained in the paint from separating or aggregating within the paint circulation path 30, and it is also possible to reduce the viscosity of the paint.

[0027] The painting head 31 has a nozzle forming surface 52 on which a plurality of nozzles 51 are arranged, and forms a paint film on the surface of the vehicle body FR by discharging the paint supplied through the supply path 32 from each of the plurality of nozzles 51. It is an inkjet type head. A nozzle row (not shown) is configured by a predetermined number of nozzles 51, and the nozzle row is provided obliquely with respect to the scanning direction which is the direction in which the painting head 31 moves, but the nozzle row may be provided along or orthogonal to the scanning direction. The detailed configuration of the painting head 31 will be omitted.

[0028] The supply path 32 is a flow path that supplies the paint stored in the paint tank toward the painting head 31. The supply path 32 is divided into different flow paths 32a, 32b, 32c by a plurality of components interposed in the supply path 32. The paint in the supply path 32 is pumped by a first gear pump 38 interposed in the middle of the supply path 32. The supply path 32 has, in order from the upstream side, a switching valve 40, a first gear pump 38, and a first three-way valve 35 as a switching unit.

[0029] The first three-way valve 35 is connected to the downstream end of the first gear pump 38 in the supply path 32. The first three-way valve 35 maintains a state in which the flow path 32c and the head flow path 31a provided in the painting head 31 communicate with each other during the painting of the vehicle body FR by the painting head 31. The first three-way valve 35 switches to a state in which the flow path 32c and the bypass flow path 33 communicate with each other when the vehicle body FR is not being painted by the painting head 31. Note that the upstream side of the flow path 32c is connected to the first gear pump 38, and the downstream side thereof is connected to the first three-way valve 35.

[0030] The bypass passage 33 connects the first three-way valve 35 and the second three-way valve 41 (to be described later), and when the painting head 31 does not perform painting, the paint supplied from the supply passage 32 bypasses the painting head 31 and is refluxed to the return passage 34.

[0031] The return passage 34 is a passage that flows the paint not used by the painting head 31 or the paint circulating in the paint circulation passage 30 toward the downstream side of the return passage 34, which is the upstream side of the supply passage 32, and returns it to the paint tank. The return passage 34 is divided into different passages 34a and 34b by a plurality of components interposed in the return passage 34. The paint in the return passage 34 is pumped by a second gear pump 42 interposed in the middle of the return passage 34. The return passage 34 has, in order from the upstream side, the second three-way valve 41 and the second gear pump 42. Note that the upstream side of the passage 34a is connected to the second three-way valve 41, and the downstream side thereof is connected to the second gear pump 42. Further, the upstream side of the passage 34b is connected to the second gear pump 42, and the downstream side thereof is connected to a paint tank (not shown).

[0032] The second three-way valve 41 is connected to the downstream end of the head passage 31b. The second three-way valve 41 maintains a state in which the head passage 31b and the passage 34a communicate with each other when the vehicle body FR is painted by the painting head 31. Further, the second three-way valve 41 switches to a state in which the bypass passage 33 and the passage 34a communicate with each other when the vehicle body FR is not painted by the painting head 31. The second gear pump 42 draws in the paint flowing through the passage 34a and pumps it to the passage 34b connected to the downstream side of the second gear pump 42.

[0033] The supply passage 32 has a switching valve 40 upstream of the first gear pump 38. The switching valve 40 is connected to the downstream end of the passage 32a. The switching valve 40 has four valve parts 40a, 40b, 40c, and 40d. The valve part 40a is connected to the upstream passage 32a, and the valve part 40b is connected to the downstream passage 32b. Therefore, when supplying paint from the paint tank to the painting head 31 or during paint circulation, the valve part 40a and the valve part 40b are opened, and the paint from the passage 32a flows toward the passage 32b.

[0034] The switching valve 40 is connected to the supply valve 36 as a supply unit. The supply valve 36 is connected to the valve portion 40c of the switching valve 40, and can selectively switch between a valve portion 36a through which the cleaning liquid supplied from the cleaning tank 43 can flow and a valve portion 36b through which the air supplied from the air compressor 44 can flow. Therefore, during cleaning, when the valve portion 36a or the valve portion 36b is opened, the cleaning liquid or air selectively flows to the downstream side of the supply passage 32.

[0035] The valve portion 40d is connected to the drain tank 45. Therefore, separately from the cleaning operation of this embodiment, when the supply passage 32 is cleaned upstream of the switching valve 40, when the valve portion 40a and the valve portion 40d are opened, the cleaning liquid and air that have flowed through the flow passage 32a connected to the opened valve portion 40a flow into the drain tank 45 through the valve portion 40d.

[0036] The cleaning control unit 37 cleans the painting head 31 by switching the supply valve 36, the first three-way valve 35, and the second three-way valve 41 in a state where the valve portion 40c and the valve portion 40b of the switching valve 40 are connected.

[0037] [Painting Head Cleaning Process] The cleaning of the painting head 31 by the cleaning control unit 37 will be described with reference to FIG. 3. FIG. 3 is a flowchart showing the cleaning process of the painting head 31 of the vehicle painting machine 10 according to this embodiment.

[0038] In step S1, the cleaning control unit 37 determines whether the cleaning process of the painting head 31 has started. When it is determined that the cleaning process has started, the process proceeds to step S2, and when it is determined that the cleaning process has not started, the process repeats step S1 again. Performing the cleaning process is determined by a control unit (not shown) of the paint circulation path 30.

[0039] In step S2, the cleaning control unit 37 opens the head channels 31a and 31b. The head channels 31a and 31b are opened by the cleaning control unit 37 switching the first three-way valve 35 to connect the channel 32c and the head channel 31a provided in the coating head 31 on the downstream side, and switching the second three-way valve 41 to connect the head channel 31b provided in the coating head 31 on the upstream side and the channel 34a.

[0040] In step S3, the cleaning control unit 37 supplies the cleaning liquid to the supply path 32. By driving the first gear pump 38 and the second gear pump 42 with the valve part 36a of the supply valve 36 open and the valve parts 40b and 40c of the switching valve 40 open, the cleaning liquid supplied from the cleaning tank 43 is supplied to the supply path 32.

[0041] In step S4, the cleaning control unit 37 determines whether or not the supply path 32 is filled with the cleaning liquid. When it is determined that the supply path 32 is filled with the cleaning liquid, the process proceeds to step S5. When it is determined that the supply path 32 is not filled with the cleaning liquid, the process returns to step S3 and the filling of the cleaning liquid continues.

[0042] Whether or not the supply path 32 is filled with the cleaning liquid may be determined by obtaining in advance through experiments or the like the volume in the flow path from the cleaning tank 43 to the first three-way valve 35 disposed at the upstream end of the coating head 31, or may be determined by the elapsed time since the start of flowing the cleaning liquid.

[0043] In step S5, the cleaning control unit 37 opens the bypass flow path 33. The cleaning control unit 37 switches the first three-way valve 35 to connect the channel 32c and the bypass flow path 33, and switches the second three-way valve 41 to connect the bypass flow path 33 and the channel 34a. As a result, the bypass flow path 33 is opened and the cleaning liquid flows into the bypass flow path without flowing into the coating head 31.

[0044] In step S6, the cleaning control unit 37 supplies air to the supply path 32. By switching the supply valve 36 to open the valve portion 36b, the air supplied from the air compressor 44 is supplied to the supply path 32. Here, the volume of the air to be supplied is set to be smaller than the volume of the cleaning liquid supplied in step S3 earlier, for example, about 10% of the volume of the cleaning liquid.

[0045] Also, in this embodiment, since the inkjet type coating head 31 is used, the pressure resistance performance of the coating head 31 is relatively low. However, in order to form two layers with the cleaning liquid later, it is necessary to set the air pressure supplied in this step S6 to be somewhat higher than the pressure resistance value of the coating head 31. However, as described above, since the volume of the air is sufficiently smaller than the volume of the cleaning liquid, if the air mixes into the cleaning liquid and becomes a gas-liquid mixed state, the overall pressure will be lower than the pressure resistance value of the coating head 31, so the coating head 31 will not be adversely affected by the height of the air pressure.

[0046] In step S7, the cleaning control unit 37 determines whether or not the elapsed time since the start of the air supply has exceeded a predetermined two-layer formation time. When it is determined that the elapsed time since the start of the air supply has exceeded the two-layer formation time, the process proceeds to step S8. When it is determined that the elapsed time has not exceeded the two-layer formation time, the process returns to step S6 and the air supply continues.

[0047] The predetermined two-layer formation time is the required time until the air and the cleaning liquid in the supply path 32 become two layers along the flow direction by supplying air into the supply path 32 while the cleaning liquid is flowing toward the bypass flow path 33 side, and is obtained in advance through experiments or the like.

[0048] In step S8, the cleaning control unit 37 opens the head flow paths 31a and 31b of the coating head 31. The cleaning control unit 37 switches the first three-way valve 35 to connect the flow path 32c and the head flow path 31a, and switches the second three-way valve 41 to connect the head flow path 31b and the flow path 34a. Thereby, the head flow paths 31a and 31b are opened.

[0049] When the head flow paths 31a and 31b are opened, the cleaning liquid and air in the supply path 32 composed of two layers flow into the head flow paths 31a and 31b. At this time, since the volume of air is sufficiently smaller than the volume of the cleaning liquid, the air is pushed into the head flow paths 31a and 31b by the cleaning liquid, resulting in a gas-liquid mixed state where the air is mixed into the cleaning liquid. When the cleaning liquid in the gas-liquid mixed state flows through the head flow paths 31a and 31b, the cleaning performance inside the flow path can be improved compared to the case where only the cleaning liquid flows.

[0050] Also, although the pressure of the air is set to be higher than the pressure resistance value of the coating head 31 in step S6, since the pressure of the air in the cleaning liquid in the gas-liquid mixed state is lower than the pressure resistance value of the coating head 31, cleaning can be performed without damaging the coating head 31.

[0051] Here, while referring to FIG. 4, the mechanism by which the cleaning liquid becomes a gas-liquid mixed state will be described. FIG. 4 is an explanatory diagram for explaining the mechanism by which the gas-liquid mixed state of the cleaning liquid occurs.

[0052] After the supply path 32 is filled with the cleaning liquid, when the cleaning liquid in the supply path 32 is made to flow into the bypass path 33 (FIG. 4A), air having a volume smaller than that of the cleaning liquid is supplied into the supply path 32. When a predetermined two-layer formation time elapses after the air is supplied, the inside of the supply path 32 becomes a state composed of two layers of air and the cleaning liquid (FIG. 4B). In this state, when the flow path is switched from the bypass path 33 to the head flow paths 31a and 31b, the air in the head flow paths 31a and 31b is pushed by the cleaning liquid, generating a cleaning liquid in a gas-liquid mixed state (FIG. 4C).

[0053] The volume of the cleaning liquid in the gas-liquid mixed state changes according to the volume of the air introduced in step S6. However, since the volume of the air is sufficiently smaller compared to the volume of the cleaning liquid, the volume of the cleaning liquid in the gas-liquid mixed state is also relatively small. Therefore, the cleaning liquid in the gas-liquid mixed state returns to the cleaning liquid not containing air after flowing through the head flow paths 31a and 31b, and the inside of the supply path 32 becomes filled with the cleaning liquid again (FIG. 4A).

[0054] Returning to FIG. 3, in step S9, the cleaning control unit 37 determines whether to repeat once again the cleaning cycle in which the cleaning liquid in the gas-liquid mixed state, which is performed from step S5 to step S8 in the cleaning process of the head flow paths 31a and 31b of the coating head 31 that is performed from step S2 to step S8, is caused to flow into the head flow paths 31a and 31b. When it is determined to repeat the cleaning cycle, the process returns to step S5, and when it is determined not to repeat the cleaning cycle, the process ends.

[0055] [Cleaning cycle] Next, with reference to FIGS. 5 and 6, the cleaning cycle of the head flow paths 31a and 31b of the coating head 31 will be described. FIG. 5 is a circuit diagram showing a part of the paint circulation path 30 of the vehicle painting machine 10 according to the present embodiment, showing a state in which the bypass flow path 33 is open. FIG. 6 is a circuit diagram showing a part of the paint circulation path 30 of the vehicle painting machine 10 according to the present embodiment, showing a state in which the head flow paths 31a and 31b are open.

[0056] As shown in FIG. 5, when the cleaning liquid supplied from the supply path 32 flows through the bypass flow path 33 and air is supplied to the supply path 32 so that the inside of the supply path 32 is composed of two layers of air and the cleaning liquid, the flow path is switched to the head flow paths 31a and 31b.

[0057] Then, as shown in FIG. 6, the cleaning liquid in which air is pushed in by the cleaning liquid to be in a gas-liquid mixed state flows through the head flow paths 31a and 31b. At this time, the inside of the head flow paths 31a and 31b is cleaned with a higher cleaning power than when cleaning with the cleaning liquid alone by the cleaning liquid in the gas-liquid mixed state.

[0058] After that, as shown in FIG. 5 again, when the flow path is switched to the bypass flow path 33 and the inside of the supply path 32 is again composed of two layers of air and the cleaning liquid, the flow path is switched to the head flow paths 31a and 31b, and as shown in FIG. 6, the cleaning liquid in a gas-liquid mixed state is caused to flow through the head flow paths 31a and 31b. In this way, from the state where the flow path is switched to the bypass flow path 33 and the air and the cleaning liquid are composed of two layers (FIG. 5) to the state where the flow path is switched to the head flow paths 31a and 31b and the cleaning liquid in a gas-liquid mixed state is caused to flow through the head flow paths 31a and 31b (FIG. 6) is taken as one cleaning cycle, and the cleaning cycle is repeated the number of cycles required for cleaning the head flow paths 31a and 31b.

[0059] [Modification Example] In the above embodiment, the bypass flow path and the head flow path are switched using the first three-way valve 35 and the second three-way valve 41, but other valves may be used as long as they can surely switch the flow path.

[0060] Also, in the above embodiment, the discharge of the cleaning liquid and the air is switched by switching one supply valve 36, but a discharge valve for the cleaning liquid and a discharge valve for the air may be provided independently, and the two discharge valves may be selectively controlled to open and close.

[0061] Also, in the above embodiment, the cleaning control unit 37 has been described as an independent control unit, but it may be incorporated into the control unit that controls the switching valve 40, the first gear pump 38, and the second gear pump 42 for integrated control.

[0062] [Supplementary Explanation of Embodiment] Each of the above-described embodiments shows a preferred specific example of the present invention. The numerical values, components, arrangement positions of the components, order of connection forms, etc. shown in the above embodiments are examples and are not intended to limit the present invention. Also, each figure is not necessarily drawn precisely.

[0063] As described above, the embodiments of the present invention have been described, but the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0064] The above-described series of processes can be executed by hardware or by software. When the series of processes is executed by software, the program constituting the software is installed from a program recording medium into a computer in which the program is incorporated in dedicated hardware, or into a general-purpose computer or the like that can execute various functions by installing various programs.

[0065] Note that the program executed by the computer may be a program in which processing is performed in time series in the order described in this specification, or may be a program in which processing is performed in parallel or at a necessary timing such as when a call is made.

[0066] [Appendix] The content described in some of the above embodiments is understood as follows, for example.

[0067] (1) Flowing the cleaning liquid in a gas-liquid mixed state into the head flow path The vehicle painting machine 10 includes an inkjet painting head 31 having a plurality of nozzles 51 for discharging paint and a head flow path 31a for supplying paint to the nozzles 51, a supply path 32 for supplying paint toward the painting head 31, a bypass flow path 33 for flowing the paint in the supply path 32 past the painting head 31 to the downstream side of the painting head 31, a first three-way valve 35 for switching the supply state of the paint from the supply path 32 between the head flow paths 31a, 31b and the bypass flow path 33, a supply valve 36 for selectively supplying a cleaning liquid and air to the supply path 32, and a cleaning control unit 37 for controlling the first three-way valve 35 and the supply valve 36 to clean the painting head 31. The cleaning control unit 37 supplies air in a state where the first three-way valve 35 is switched to the supply state to the bypass flow path 33 and the supply path 32 is filled with the cleaning liquid, and with the air and the cleaning liquid in a two-layer state along the flow direction, switches the first three-way valve 35 to the supply state to the head flow paths 31a, 31b to flow the cleaning liquid into the head flow paths 31a, 31b, thereby cleaning the painting head 31 with the cleaning liquid in a gas-liquid mixed state.

[0068] Thereby, in a state where the supply path 32 is filled with the cleaning liquid, the cleaning liquid is supplied to the bypass flow path 33, and when the air and the cleaning liquid are in a two-layer state, the flow path can be switched to the head flow paths 31a, 31b to form a cleaning liquid in a gas-liquid mixed state. Therefore, even in the vehicle painting machine 10 having the inkjet painting head 31 with a low pressure resistance value in terms of structure, the cleanability of the painting head 31 can be improved without using high-pressure compressed air or a cleaning liquid containing microbubbles generated at high pressure.

[0069] (2) Timing of flowing into the head flow path The cleaning control unit 37 may switch the supply state of the paint from the supply path 32 to the head flow paths 31a, 31b when the air and the cleaning liquid are in a two-layer state in the supply path 32.

[0070] As a result, air is pushed into the head channels 31a and 31b by the cleaning liquid, so that a cleaning liquid in a gas-liquid mixed state with air mixed therein can be formed. Therefore, the cleaning liquid can exhibit sufficient cleaning performance within the head channels 31a and 31b.

[0071] (3) Time determination of the gas-liquid mixed state When a predetermined two-layer formation time has elapsed since air was first supplied to the supply path 32, the cleaning control unit 37 may determine that air and the cleaning liquid have become two layers in the supply path 32.

[0072] Thereby, since it is possible to determine by time that the inside of the supply path 32 has become two layers of the cleaning liquid and air, by obtaining the time in advance through experiments or the like, it is possible to accurately predict that the cleaning liquid has flowed into the head channels 31a and 31b and a gas-liquid mixed state has been generated.

[0073] In addition, even though air and the cleaning liquid have become two layers in the supply path 32, it is also possible to prevent the time until the start of cleaning from being delayed due to the flow path not being switched to the head channels 31a and 31b.

[0074] (4) Air < cleaning liquid The supply amount to the supply path 32 by the supply valve 36 controlled by the cleaning control unit may be less for air than for the cleaning liquid.

[0075] Thereby, when switching the flow path through which the cleaning liquid flows from the bypass flow path 33 to the head channels 31a and 31b, it is possible to prevent the gas-liquid mixed state from being insufficient and air itself from being sent to the head channels 31a and 31b, and high-pressure air from being sent to the coating head 31 with a low pressure resistance value.

[0076] In addition, it is possible to prevent air itself from being sent to the nozzle 51 and the paint from not being discharged from the nozzle 51 after the cleaning is completed.

Explanation of reference numerals

[0077] 10 Vehicle painting machine 31 Painting head 31a Head flow path 31b Head flow path 32 Supply path 33 Bypass flow path 35 First three-way valve (switching part) 36 Supply valve (supply part) 37 Cleaning control unit 51 Nozzle

Claims

1. an inkjet type paint head having a plurality of nozzles for ejecting paint and a head flow path for supplying the paint to the nozzles; A supply passage for supplying the paint toward the painting head; a bypass flow path that causes the paint in the supply path to bypass the paint head and flow to a downstream side of the paint head; a switching unit that switches a supply state of the paint from the supply passage between the head flow passage and the bypass flow passage; a supply unit that selectively supplies a cleaning liquid and air to the supply path; a cleaning control unit that controls the switching unit and the supply unit to clean the coating head; Equipped with the cleaning control unit supplies the air in a state where the switching unit is switched to a supply state to the bypass flow path and the supply path is filled with the cleaning liquid, and in a state where the air and the cleaning liquid form two layers along a flow direction, the switching unit is switched to a supply state to the head flow path and the cleaning liquid flows into the head flow path, thereby cleaning the coating head with the cleaning liquid in an air-liquid mixed state. A vehicle paint sprayer characterized by the above.

2. The vehicle sprayer according to claim 1, the cleaning control unit switches a supply state of the paint from the supply path to the head flow path when the air and the cleaning liquid form two layers in the supply path. A vehicle paint sprayer characterized by the above.

3. 3. The vehicle sprayer according to claim 2, the cleaning control unit determines that the air and the cleaning liquid have formed two layers in the supply path when a predetermined two-layer formation time has elapsed since the air was first supplied to the supply path, A vehicle paint sprayer characterized by the above.

4. The vehicle sprayer according to claim 1, The amount of the air supplied to the supply path by the supply unit controlled by the cleaning control unit is less than the amount of the cleaning liquid. A vehicle paint sprayer characterized by the above.

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