Coating robot

Abstract

The purpose of the present disclosure is to provide a painting robot capable of reducing the influence of pressure fluctuations and setting a pressure range in which a pneumatic control valve can be operated. The coating robot includes: a coating head unit including a coating head including a plurality of nozzles for discharging liquid droplets and a piezoelectric substrate for extruding the liquid droplets from the nozzles; a robot arm that moves the coating head unit to a desired position; and a paint supply mechanism provided across between the robot arm and the coating head unit. In addition, the paint supply mechanism is provided with: a paint supply passage for supplying paint to the coating head; a return flow path that recovers the paint that has not been discharged from the nozzle; an AOPR provided in the paint supply passage and capable of adjusting the valve opening according to the controlled air pressure; and an orifice that is provided in the paint supply passage on the downstream side of the AOPR toward the coating head side.

Description

Technical Field

[0001] The invention relates to a painting robot. Background Art

[0002] Robotic painting using robots has become the mainstream in the painting production line of vehicles such as automobiles. As an example of a structure related to the robotic painting, there is disclosed a painting robot such as disclosed in Patent Document 1, which has a painting head (56) capable of spraying paint by the action of a piezoelectric substrate (109) and a paint circulation device (51) for supplying paint to the painting head (56).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 7203258 Summary of the invention

[0006] Problems to be Solved by the Invention

[0007] However, in the configuration of Patent Document 1, the influence of pressure fluctuations affects the stable discharge of the paint from the coating head. For example, for a pressure input of 5 kPa, if it is assumed that a pressure fluctuation of about ±1 kPa occurs due to the driving state of the gear pump (62) that supplies the paint from the upstream side and the operation of the proportional valve (71), the proportion of the influence of the pressure fluctuation is, for example, 20%, and there is a risk that the discharge of the paint becomes unstable.

[0008] In addition, in the environment of painting vehicles, in order to achieve explosion-proof, the use of AOPR (Air Operate Paint Regulator) controlled by air pressure is being considered instead of using a proportional valve which is an electrical device. However, since the operable pressure range of AOPR is higher than that of the proportional control valve, AOPR cannot be used in the structure disclosed in Patent Document 1.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a painting robot capable of reducing the influence of pressure fluctuations and setting a pressure range within which a pneumatic control valve can be operated.

[0010] Means for solving problems

[0011] In order to solve the above-mentioned problems, according to a first aspect of the present invention, there is provided a painting robot, characterized in that it performs painting of a vehicle and comprises: a painting head unit having a painting head, the painting head having a plurality of nozzles for ejecting droplets and a piezoelectric substrate for squeezing droplets from the nozzles by driving; a robot arm, the painting head unit being mounted on the front end of the robot arm, and the robot arm moving the painting head unit to a desired position; and a paint supply mechanism, which is arranged across the robot arm and the painting head unit, the paint supply mechanism comprising: a paint supply passage, which supplies paint to the painting head; a return flow passage, which is connected to the paint discharge side of the painting head and recovers the paint that has not been ejected from the nozzle; a pneumatic control valve, which is arranged in the paint supply passage and can adjust the valve opening according to the controlled air pressure; and a booster mechanism, which is arranged in the paint supply passage at a position downstream of the pneumatic control valve toward the painting head side or upstream of the pneumatic control valve, so as to increase the pressure of the paint supplied to the pneumatic control valve.

[0012] In the above aspect, it is preferable that an electrically operated valve whose valve opening degree can be adjusted by electrical operation is provided in the return flow path.

[0013] In any of the above aspects, it is preferred that the pressure increasing mechanism is a throttle hole in which the inner diameter of the paint supply passage is narrowed, and the throttle hole is composed of a single hole portion or a plurality of hole portions.

[0014] In any one of the above aspects or a combination thereof, preferably, the pressure increasing mechanism is a removal filter that removes foreign matter contained in the paint flowing in the paint supply passage.

[0015] In addition, in any of the above-mentioned schemes or their combination, it is preferred that a bypass flow path is provided in the paint supply mechanism, which connects the paint supply path and the return flow path and allows the paint to circulate in parallel with the coating head, and the boosting mechanism is provided at a position on the upstream side of the paint supply path compared to the bypass flow path.

[0016] In any one of the above schemes or a combination thereof, preferably, the throttle hole can adjust the opening of the flow path through which the coating material flows.

[0017] Effects of the Invention

[0018] According to the present invention, it is possible to provide a painting robot which can reduce the influence of pressure fluctuations and set the pressure range within which the pneumatic control valve can be operated. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram showing the overall structure of a painting robot according to one embodiment of the present invention.

[0020] Figure 2 It is shown from the front view Figure 1 The illustrated embodiment is a front view of a state in which a nozzle for ejecting paint in a painting robot forms a surface.

[0021] Figure 3 It is shown in Figure 1 The drawing shows a state where a plurality of painting heads of a painting robot are arranged in a staggered manner.

[0022] Figure 4 It is shown in Figure 1 FIG. 2 is a diagram showing a schematic configuration of supplying paint to each nozzle in a painting robot shown.

[0023] Figure 5 It is shown Figure 4 A cross-sectional view showing the structure of the row direction supply flow path, the nozzle pressurizing chamber, and the row direction discharge flow path and its vicinity.

[0024] Figure 6 is shown with Figure 2 This is a plan view showing the configuration of the nozzle forming surface in another coating head unit that is different from the coating head unit shown.

[0025] Figure 7 It is shown Figure 1 A diagram schematically illustrates the configuration of a paint supply mechanism and the like included in the painting robot shown.

[0026] Figure 8 It is shown that the Figure 7 FIG. 2 is a diagram showing an example of the configuration of an orifice of a paint supply mechanism.

[0027] Fig. 9 is shown with Figure 8 The diagrams of the throttle orifices shown have different throttle orifice configurations.

[0028] Fig.10 is shown with Figure 8 and Fig. 9 The diagrams of the throttle orifices shown have different throttle orifice configurations.

[0029] Fig.11 It is shown Figure 1 A schematic diagram of a control configuration in a painting robot is shown.

[0030] Fig.12 It is shown that the Figure 7 The graph shows the experimental results of the relationship between the flow rate and the pressure loss when the inner diameter of the orifice of the coating material supply mechanism is 0.75 mm, 1.0 mm, and 1.2 mm.

[0031] Description of Reference Numerals

[0032] 10: Painting robot, 20: Robot body, 21: Base, 22a: First rotation axis, 22b: Second rotation axis, 22c: Third rotation axis, 22d: Fourth rotation axis, 22e: Fifth rotation axis, 22f: Sixth rotation axis, 24: First rotation arm, 25: Second rotation arm, 26: Rotation arm, 27: Wrist, 50: Painting head unit, 52: Nozzle forming surface, 53: Painting head, 54: Nozzle, 55: Nozzle array, 55A: First nozzle array, 55B: Second nozzle array Nozzle array, 57: Supply side large flow path, 58: Column direction supply flow path, 59: Nozzle pressurizing chamber, 59a: Nozzle supply flow path, 59b: Nozzle discharge flow path, 60: Column direction discharge flow path, 61: Discharge side large flow path, 62: Piezoelectric substrate, 63a: Piezoelectric ceramic layer, 63b: Piezoelectric ceramic layer, 64: Common electrode, 65: Independent electrode, 70: Paint supply mechanism, 71: Paint circulation path, 72: Paint supply passage, 73: Return flow path, 74: Bypass flow path, 75: External Supply passage, 76: Bubble removal component, 77: Three-way valve, 78: Opening and closing valve, 79: Three-way valve, 80: Switching valve, 81: Discharge passage, 90: Supply pump (corresponding to paint supply mechanism), 91: Suction pump (corresponding to paint recovery mechanism), 92: AOPR (corresponding to pneumatic control valve), 93: Secondary side proportional control valve (corresponding to electric operation valve), 94: Degassing module, 95: Removal filter, 96: Orifice (corresponding to boosting mechanism), 97: Suction pipeline, 98: Vacuum pump, 100: control unit, 110: main control unit, 120: arm control unit, 121: memory for arm, 130: head control unit, 140: paint supply control unit, 150: memory for control, 200: image processing device, 210: image processing unit, 220: memory, 300: position sensor, 310: tilt sensor (corresponding to angle detection mechanism), FM1: first flow meter, FM2: second flow meter, R1: robot arm, S1 to S8: pressure sensor DETAILED DESCRIPTION

[0033] Hereinafter, the painting robot 10 according to each embodiment of the present invention will be described based on the drawings. It should be noted that in the following description, as required, the X direction is set as the long side direction of the nozzle forming surface 52 (painting head 53), and the X1 side is Figure 2 The right side of the X2 side is Figure 2 In addition, the Y direction is set as the short side direction (width direction) of the nozzle forming surface 52 (coating head 53), and the Y1 side is Figure 2 The upper side of the paper in the figure is Y2 side. Figure 2 The lower side of the paper.

[0034] (1. Overview of the Spray-Type Painting Robot 10)

[0035] The painting robot 10 of this embodiment "paints" a painting object such as a vehicle or a vehicle part (hereinafter, a vehicle part that will become a part of a vehicle is also described as a vehicle) on a painting line in an automobile manufacturing plant, with the purpose of forming a coating film on the surface of the painting object to provide surface protection and beauty. Therefore, it is necessary to paint the vehicles that move along the painting production line at specified intervals within a certain period of time with the desired painting quality.

[0036] In addition, in the painting robot 10 of this embodiment, not only the above-mentioned coating film can be formed, but also various designs and images can be formed for painting objects such as vehicles and vehicle parts. It should be noted that the painting objects are not limited to vehicles and vehicle parts, as long as they are parts that need to be painted, they can also be various parts other than automobiles (for example, exterior parts of airplanes and railways), etc.

[0037] (1-1. Overall Structure of Spray-Type Painting Robot 10)

[0038] Figure 1 1 is a schematic diagram showing the overall structure of the painting robot 10 according to the first embodiment of the present invention. Figure 1 As shown, the painting robot 10 has a robot body 20 and a painting head unit 50 as main components. As an example, Figure 1 The painting robot 10 shown in the figure is a six-axis vertical articulated robot, but the painting robot 10 may be any type of robot other than a six-axis vertical articulated robot, such as a horizontal articulated robot, an orthogonal robot, or the like.

[0039] (1-2. About the robot body)

[0040] like Figure 1 As shown, the robot body 20 mainly includes a base 21, first to sixth rotation axes 22a to 22f, a leg 23, a first rotation arm 24, a second rotation arm 25, a rotation arm 26, a wrist 27, and a motor (not shown) for driving these parts. It should be noted that the part from the leg 23 to the wrist 27 corresponds to the robot arm R1, but components other than the above such as the base 21 may also correspond to the robot arm R1.

[0041] The base 21 among these components is a part installed at a location such as the ground, and the base 21 may also be able to move relative to the location. In addition, the leg 23 is a part erected upward from the base 21, and is provided in a manner that can rotate relative to the base 21 by driving a motor (first motor) not shown in the figure via a first rotating shaft 22a. It should be noted that the leg 23 may also be configured not to rotate relative to the base 21.

[0042] In addition, a first rotating arm 24 is provided at the upper end of the leg 23, and the first rotating arm 24 can be rotated by driving a motor (second motor) not shown in the figure via the second rotating shaft 22b. In addition, a second rotating arm 25 is provided at the front end side of the first rotating arm 24, and the second rotating arm 25 can be rotated by driving a motor (third motor) not shown in the figure via the third rotating shaft 22c.

[0043] In addition, a rotating arm 26 is provided at the front end side of the second rotating arm 25, and the rotating arm 26 can rotate around the central axis of the second rotating arm 25. The rotating arm 26 can rotate by means of the fourth rotating shaft 22d driven by a motor (fourth motor) not shown in the figure. In addition, a wrist 27 is provided at the front end side of the rotating arm 26. The wrist 27 can rotate around multiple (for example, two) shafts in different directions. Figure 1 In the embodiment, the rotation axes capable of performing the rotational motion are respectively set as the fifth rotation axis 22e and the sixth rotation axis 22f. Thus, the orientation of the coating head unit 50 can be controlled with high precision. It should be noted that the number of the shaft portions may be any number of two or more.

[0044] Furthermore, a coating head unit 50 is attached to the arm 27 , and the coating head unit 50 is detachably provided with respect to the arm 27 .

[0045] (1-3. About the coating head unit)

[0046] Next, the coating head unit 50 will be described. Figure 2 1 is a diagram showing a state in which a nozzle forming surface 52 for ejecting paint in a coating head unit 50 is viewed from the front. Figure 2 As shown, the coating head unit 50 includes a head cover portion (not shown), and various structures are built into the head cover portion. Figure 2 As shown, a plurality of nozzle arrays 55 are provided on the nozzle forming surface 52, and in the nozzle arrays 55, the nozzles 54 are arranged in a direction inclined relative to the long side direction of the coating head unit 50. In the present embodiment, the nozzle array 55 is provided with a first nozzle array 55A located on one side (Y2 side) of the main scanning direction (Y direction) and a second nozzle array 55B located on the other side (Y1 side) of the main scanning direction.

[0047] When spraying paint, the driving timing of each nozzle 54 is controlled so that the droplets sprayed from the nozzles 54 in the second nozzle row 55B land between the droplets sprayed from the adjacent nozzles 54 in the first nozzle row 55A. This can increase the dot density during painting.

[0048] By the way, if Figure 2As shown in FIG. 5 , a single coating head 53 is present on the nozzle forming surface 52. However, a coating head group consisting of a plurality of coating heads 53 may also be present on the nozzle forming surface 52. In this case, as an example, Figure 3 As shown, a configuration in which a plurality of coating heads 53 are aligned and arranged in a staggered manner can be exemplified, but the coating heads 53 in the coating head group may not be arranged in a staggered manner.

[0049] Figure 4 This is a diagram showing a schematic configuration for supplying paint to each nozzle 54 . Figure 5 2 is a cross-sectional view showing the structure of the column direction supply flow path 58, the nozzle pressurizing chamber 59, and the column direction discharge flow path 60. Figure 4 and Figure 5 As shown, the coating head 53 includes a supply side large flow path 57, a column direction supply flow path 58, a nozzle pressurizing chamber 59, a column direction discharge flow path 60, and a discharge side large flow path 61. The supply side large flow path 57 is a flow path for supplying paint from a paint supply passage 72 of a paint supply mechanism 70 described later. In addition, the column direction supply flow path 58 is a flow path for diverting the paint in the supply side large flow path 57.

[0050] The nozzle pressurizing chamber 59 is connected to the row direction supply flow path 58 via the nozzle supply flow path 59a. Thus, the paint is supplied from the row direction supply flow path 58 to the nozzle pressurizing chamber 59. The nozzle pressurizing chamber 59 is provided in accordance with the number of nozzles 54, and the paint inside can be ejected from the nozzle 54 using the piezoelectric substrate 62 described later.

[0051] In addition, the nozzle pressurizing chamber 59 is connected to the column-direction discharge flow path 60 via the nozzle discharge flow path 59b. Therefore, the paint that is not ejected from the nozzle 54 is discharged from the nozzle pressurizing chamber 59 to the column-direction discharge flow path 60 via the nozzle discharge flow path 59b. In addition, the column-direction discharge flow path 60 is connected to the discharge-side large flow path 61. The discharge-side large flow path 61 is a flow path where the paint discharged from each column-direction discharge flow path 60 merges. The discharge-side large flow path 61 is connected to the return flow path 73 of the paint supply mechanism 70 described later.

[0052] With such a configuration, the paint supplied from the paint supply passage 72 of the paint supply mechanism 70 described later is ejected from the nozzle 54 via the supply-side large flow path 57, the row-direction supply flow path 58, the nozzle supply flow path 59a, and the nozzle pressurizing chamber 59. In addition, the paint not ejected from the nozzle 54 is returned to the return flow path 73 of the paint supply mechanism 70 described later via the nozzle pressurizing chamber 59, the nozzle discharge flow path 59b, the row-direction discharge flow path 60, and the discharge-side large flow path 61.

[0053] It should be noted that in Figure 4In the illustrated configuration, one column-direction discharge flow path 60 is disposed corresponding to one column-direction supply flow path 58. However, a plurality of (e.g., two) column-direction discharge flow paths 60 may be disposed corresponding to one column-direction supply flow path 58. In addition, one column-direction discharge flow path 60 may be disposed corresponding to a plurality of column-direction supply flow paths 58.

[0054] In addition, if Figure 5 As shown in FIG. 1 , a piezoelectric substrate 62 is disposed on the top surface of the nozzle pressurizing chamber 59 (the surface on the opposite side to the nozzle 54). The piezoelectric substrate 62 includes two piezoelectric ceramic layers 63a and 63b as piezoelectric bodies, and further includes a common electrode 64 and an independent electrode 65. The piezoelectric ceramic layers 63a and 63b are components that can be expanded and contracted by applying a voltage from the outside. As such piezoelectric ceramic layers 63a and 63b, lead zirconate titanate (PZT) system, NaNbO 3 Series, BaTiO 3 System, (BiNa)NbO 3 Department, BiNaNb 5 O 15 Series and other ceramic materials.

[0055] In addition, if Figure 5 As shown, the common electrode 64 is arranged between the piezoelectric ceramic layer 63a and the piezoelectric ceramic layer 63b. In addition, a surface electrode for the common electrode (not shown) is formed on the upper surface of the piezoelectric substrate 62. These common electrodes 64 and the surface electrodes for the common electrode are electrically connected through the through conductor not shown in the piezoelectric ceramic layer 63a. In addition, the independent electrodes 65 are respectively arranged at the positions opposite to the above-mentioned nozzle pressurization chamber 59. In addition, the portion of the piezoelectric ceramic layer 63a sandwiched by the common electrode 64 and the independent electrode 65 is polarized in the thickness direction. Therefore, when a voltage is applied to the independent electrode 65, the piezoelectric ceramic layer 63a is deformed due to the piezoelectric effect. Therefore, when a prescribed driving signal is applied to the independent electrode 65, the piezoelectric ceramic layer 63b changes relatively in a manner that reduces the volume of the nozzle pressurization chamber 59, thereby spraying the paint.

[0056] It should be noted that in Figure 5 In the embodiment, the common electrode 64 is disposed on the top surface of the nozzle pressurizing chamber 59, but the common electrode 64 is not limited to Figure 5 The structure shown in FIG is arranged on the top surface of the nozzle pressurizing chamber 59. For example, the common electrode 64 may also be arranged on the side surface of the nozzle pressurizing chamber 59 (a surface perpendicular or substantially perpendicular to the above-mentioned top surface). In addition, any structure that can well eject the paint from the nozzle 54 may be adopted.

[0057] (1-4. Other configurations of the coating head unit)

[0058] Next, other configurations of the coating head unit 50 will be described. Figure 6 FIG. 5 is a top view showing the structure of the nozzle forming surface 52 of another coating head unit 50. Figure 6 As shown in FIG. 1 , the nozzle array 55 may be formed by arranging a plurality of nozzles 54 along the short side direction (width direction; Y direction) of the coating head 53. Figure 6 In the illustrated configuration, a plurality of nozzles 54 are arranged along the short side direction (width direction; main scanning direction) of the coating head 53 to form a nozzle array 55, but a configuration in which only one (single) nozzle 54 is arranged in the short side direction (width direction; main scanning direction) of the coating head 53 may also be used. That is, the nozzle array 55 may also be composed of one nozzle 54.

[0059] In addition, when using Figure 6 When the coating head 53 shown in FIG. 1 is used to coat a vehicle, the coating may be performed with the long side direction of the coating head 53 slightly inclined relative to the main scanning direction of the coating head 53. Figure 2 In the configuration of the coating head 53 shown in FIG. 1 , the nozzle array 55 is inclined at an angle α relative to the main scanning direction. The long side direction of the coating head 53 is inclined at an angle α relative to the main scanning direction of the coating head 53. In such an inclined state, the coating can be sprayed at the same angle as in FIG. 1 by adjusting the spray timing of the coating from each nozzle 54. Figure 2 The coating head 53 shown in FIG.

[0060] (1-5. About paint supply mechanism)

[0061] Next, the coating material supply mechanism 70 and the air bubble removing member and the flow meter included in the coating material supply mechanism 70 will be described.

[0062] Figure 7 1 is a diagram showing a schematic configuration of a paint supply mechanism 70, etc. The paint supply mechanism 70 includes a paint circulation path 71, an external supply path 75, a bubble removal member 76, a supply pump 90, a suction pump 91, an AOPR (Air Operate Paint Regulator) 92, a secondary side proportional control valve 93, a degassing module 94, a removal filter 95, an orifice 96, pressure sensors S1 to S8, a first flow meter FM1, and a second flow meter FM2 as main components.

[0063] The paint circulation path 71 is a flow path for circulating the paint, and has a paint supply path 72, a return path 73, and a bypass path 74. The paint supply path 72 is a flow path for supplying the paint supplied from the external supply path 75 or returned from the return path 73 to the coating head 53, and is connected to the above-mentioned supply side large path 57.

[0064] The return flow path 73 is connected to the discharge-side large flow path 61 of the coating head 53 , and is a flow path for returning the coating material that has not been discharged from the coating head 53 to the bubble removing member 76 .

[0065] The bypass flow path 74 is a flow path connecting the paint supply path 72 and the return flow path 73. That is, the bypass flow path 74 is provided in parallel with the coating head 53, and when the paint is not sprayed from the coating head 53, the paint flows into the bypass flow path 74 by switching the operation of the three-way valve 77 described later.

[0066] The external supply passage 75 is a pipe for supplying the paint supplied from a paint storage portion such as a circulation tank to the inside of the tank body of the bubble removing member 76 .

[0067] The bubble removal component 76 is a component for removing bubbles contained in the paint. The bubble removal component 76 is provided at a stable position outside the robot arm R1 where the posture is unchanged. In addition, the bubble removal component 76 is connected to the paint supply passage 72 in a manner that the paint can be supplied to the paint supply passage 72, and is connected to the return flow passage 73 in a manner that the paint is supplied from the return flow passage 73. The bubble removal component 76 includes a tank body that can be sealed relative to the outside, and the tank body is provided with an exhaust port for exhausting gas generated by bubbles accumulated inside.

[0068] In addition, the paint supply passage 72 is connected to a three-way valve 77 at a position on the downstream side compared to the AOPR 92 described later. The three-way valve 77 is connected to the middle part of the paint supply passage 72 and is also connected to the bypass flow path 74. Therefore, during painting, the upstream side and the downstream side of the paint supply passage 72 compared to the three-way valve 77 are opened, and the paint is supplied to the painting head 53. On the other hand, when painting is not performed, the paint is switched to flow from the paint supply passage 72 to the bypass flow path 74, but the paint is not supplied to the downstream side (painting head 53 side) of the paint supply passage 72.

[0069] In addition, an on-off valve 78 is provided in the middle of the bypass flow path 74. The on-off valve 78 is operated to open, so that the paint can flow in the bypass flow path 74.

[0070] In addition, a three-way valve 79 is connected to the bypass flow path 74 at a position on the downstream side compared to the on-off valve 78, and the three-way valve 79 is connected to the upstream side (i.e., the coating head 53 side of the return flow path 73) and the downstream side (i.e., the suction pump 91 side of the return flow path 73 described later). Therefore, when painting is performed, the upstream side and the downstream side of the return flow path 73 compared to the three-way valve 79 are in an open state, and the paint that is not sprayed from the coating head 53 flows to the downstream side of the return flow path 73. On the other hand, when not painting, the three-way valve 79 is switched so that the paint flowing in the bypass flow path 74 flows to the downstream side (the suction pump 91 side) of the return flow path 73.

[0071] In addition, a switching valve 80 is arranged at a position on the downstream side of the return flow path 73 compared to the suction pump 91 described later. The switching valve 80 is also a three-way valve, and is connected to the discharge passage 81 in addition to the upstream side and the downstream side of the return flow path 73. In a normal state, the switching valve 80 is in a state where the paint flows on the upstream side and the downstream side of the return flow path 73. However, in a case where, for example, a cleaning liquid flows from the paint supply passage 72 via the coating head 53 or the bypass flow path 74 to the return flow path 73, the operation of the switching valve 80 is switched, and the cleaning liquid (waste liquid) is discharged via the discharge passage 81.

[0072] It should be noted that the return flow path 73 is connected to the bubble removing member 76 at a position on the downstream side of the switching valve 80 .

[0073] In addition, a supply pump 90 is connected to the middle part of the paint supply passage 72. It should be noted that the supply pump 90 corresponds to the paint transfer mechanism and the paint supply mechanism. The supply pump 90 is a mechanism that applies positive pressure to the paint flowing in the paint supply passage 72 to the downstream side compared to the supply pump 90. It should be noted that as the supply pump 90, it is preferred to use a gear pump that can control the supply amount of the paint by controlling the rotation speed. However, the supply pump 90 can also use a pump other than a gear pump. The supply pump 90 is controlled to operate by the control unit 100 described later. Thereby, the operation of the supply pump 90 can be controlled in a manner to become a specified pressure setting value.

[0074] In addition, a suction pump 91 is connected to the middle part of the return flow path 73. It should be noted that the suction pump 91 corresponds to the paint transfer mechanism and the paint recovery mechanism. The suction pump 91 is a mechanism that applies negative pressure to the paint flowing in the return flow path 73 to the upstream side compared with the supply pump 90. It should be noted that as the suction pump 91, similarly to the above-mentioned supply pump 90, a gear pump that can control the supply amount of the paint by controlling the rotation speed is preferably used. However, the suction pump 91 can also use a pump other than a gear pump. The suction pump 91 is also controlled by the control unit 100 described later. Thus, the action of the suction pump 91 can be controlled so that its downstream side becomes a specified pressure setting value.

[0075] In addition, in the paint supply passage 72, an AOPR 92 is arranged at a position on the downstream side compared to the supply pump 90. The AOPR 92 is a regulator for paint, which is used to control the pressure of the paint supplied from the AOPR 92 according to the input air pressure (keep it constant). That is, the AOPR 92 is set to control the pressure of the paint supplied from the AOPR 92 (maintain its pressure) at a predetermined ratio (for example, 1 / 20 times to 2 times, etc.) to the input air pressure. Therefore, since the AOPR 92 is not electrically controlled but controlled by air pressure, it can be used even in an explosion-proof environment where it is difficult to use electrical equipment.

[0076] The opening degree of the AOPR 92 can be adjusted by the control gas pressure under the control of the control unit 100 described later. Thus, the pressure on the downstream side of the AOPR 92 can be controlled to a predetermined pressure setting value according to the pressure on the upstream side of the AOPR 92.

[0077] In addition, in the return flow path 73, a secondary side proportional control valve 93 is arranged at a position closer to the upstream side than the suction pump 91. The secondary side proportional control valve 93 relieves the pulsation in the suction pump 91 and sucks the paint at a constant pressure (negative pressure). The secondary side proportional control valve 93 can also adjust the opening corresponding to the control air pressure and the electric signal by the control of the control unit 100 described later. Thus, the pressure on the upstream side of the secondary side proportional control valve 93 can be controlled to a predetermined pressure setting value corresponding to the pressure on the downstream side of the secondary side proportional control valve 93.

[0078] It should be noted that, in the present embodiment, the AOPR 92 is disposed on the upstream side of the coating head 53, and the paint supply pressure is controlled by the AOPR 92. Therefore, compared with the case where an electrically controlled proportional control valve is used without using the AOPR 92, the pressure fluctuation of the supplied paint can be suppressed to a lower level in the secondary side proportional control valve 93. Therefore, the pressure control of the secondary side proportional control valve 93 by the control unit 100 becomes easy.

[0079] In addition, a degassing module 94 is arranged in the paint supply passage 72 at a position downstream of the supply pump 90 and upstream of the AOPR 92. The degassing module 94 is arranged downstream of the paint supply passage 72 compared to the removal filter 95 described later, and is a component for removing (degassing) dissolved gas dissolved in the paint.

[0080] In addition, a removal filter 95 is arranged in the paint supply passage 72 at a position upstream of the degassing module 94 and downstream of the supply pump 90. The removal filter 95 removes foreign matter contained in the paint flowing in the paint supply passage 72. The removal filter 95 reliably removes coarse foreign matter and pigment aggregates from the paint containing the pigment, for example, to keep the coating head 53 in normal operation.

[0081] It should be noted that a removal filter similar to the removal filter 95 may be additionally provided between the degassing module 94 and the AOPR 92. In this case, the additional removal filter corresponds to the boosting mechanism, but the removal filter 95 different from the additional removal filter may correspond to the boosting mechanism, or both the additional removal filter and the removal filter 95 may correspond to the boosting mechanism. In addition, the removal filter 95 may not be provided at a position upstream of the degassing module 94, but may be provided between the degassing module 94 and the AOPR 92.

[0082] In addition, in the paint supply passage 72, a throttle hole 96 corresponding to the pressure-increasing mechanism is provided at a position on the downstream side compared with the AOPR 92. The throttle hole 96 is a portion where the inner diameter of the paint supply passage 72 is narrower (smaller in diameter) than other portions of the paint supply passage 72, and has a predetermined length. However, the throttle hole 96 may also be configured to have a shorter length by providing an orifice plate, for example.

[0083] In addition, various types of throttle holes 96 can be used. For example, the throttle holes 96 can be as follows: Figure 8 As shown, the inner diameter of the central portion of the paint supply passage 72 is narrowed over a predetermined length. In this case, the throttle hole 96 may also be as shown in FIG. Fig. 9 As shown, the inner diameter of the central portion of the coating material supply passage 72 is about Figure 8 The structure shown is a type that is narrowed over a sufficiently long prescribed length L. In addition, the throttle hole 96 may also be as Fig.10 The type shown is composed of a plurality of small-diameter holes. In addition, the throttle hole 96 can also be a variable throttle hole that changes the opening area by air pressure-based control or electrical control.

[0084] It should be noted that as an example of the dimensions of the paint supply passage 72 and the throttling hole 96, the following example can be cited: when the inner diameter of the paint supply passage 72 excluding the throttling hole 96 is set to 2.5 to 8 mm, the inner diameter of the throttling hole 96 is set to 0.1 to 5 mm, and in addition, the length of the throttling hole 96 is set to 0.1 to 5 mm, but appropriate dimensions other than these dimensions may also be used.

[0085] Due to the presence of the throttle hole 96, pressure loss occurs on the upstream side of the throttle hole 96 in the paint supply passage 72 due to the viscosity of the paint. As a result, pressure rise occurs in the AOPR 92. Here, the AOPR 92 is in a state where the lowest pressure value of the operable pressure range is higher than that of the electrically controlled proportional control valve. In addition, the AOPR 92 has the following characteristics, that is, the pressure can be adjusted (pressure controlled) with a smaller error on the side where the input air pressure is higher than on the side where the input air pressure is lower.

[0086] As an example of the control of the above-mentioned AOPR92, it has been confirmed through experiments that when the paint is set to a specified flow rate, when there is no throttle hole 96 in the paint supply passage 72, the air pressure required to be input to the AOPR92 is 5KPa. In this case, if the air pressure required to be input changes from 5KPa by ±1KPa, the pressure will change by about 20%. On the other hand, when a specified throttle hole 96 is provided in the paint supply passage 72, the air pressure required to be input to the AOPR92 is 17KPa. In this case, even if the air pressure required to be input changes from 17KPa by ±1KPa, the pressure change is about 5.9%, which can reduce the influence of the pressure change.

[0087] In addition, as another example of the control of AOPR92, it has been confirmed through experiments that when the paint is set to a specified flow rate, when there is no throttle hole 96 in the paint supply passage 72, the air pressure required to be input to AOPR92 is 15KPa. In this case, if the air pressure required to be input changes from 15KPa by ±1KPa, the pressure will change by about 6.7%. On the other hand, when a specified throttle hole 96 is provided in the paint supply passage 72, the air pressure required to be input to AOPR92 is 39KPa. In this case, even if the air pressure required to be input changes from 39KPa by ±1KPa, the pressure change is about 2.6%, which can reduce the influence of the pressure change.

[0088] Next, the pressure sensors S1 to S8 and the flow meters FM1 and FM2 are described. In the paint supply passage 72, the pressure sensor S1 is arranged on the upstream side of the supply pump 90. In addition, in the paint supply passage 72, the pressure sensor S2 is arranged at a position downstream of the supply pump 90 and upstream of the removal filter 95. The pressure sensor S1 measures the supply pressure of the paint to the supply pump 90 and sends the measurement result to the control unit 100. In addition, the pressure sensor S2 measures the pressure of the paint ejected from the supply pump 90 and sends the measurement result to the control unit 100.

[0089] In this way, by measuring the pressure of the paint on the upstream and downstream sides of the supply pump 90 using the pressure sensors S1 and S2, the estimated pressure of the supply pump 90 can be measured with high accuracy. It should be noted that the estimated pressure of the supply pump 90 can be set to the average of the pressure value of the pressure sensor S1 and the pressure value of the pressure sensor S2, or to the pressure value of either one of them. In addition, the above-mentioned estimated pressure is used to calculate the water head pressure and the water head pressure difference.

[0090] In addition, the degassing module 94 is connected to a vacuum pump 98 via a suction line 97. As described above, the vacuum pump 98 is a device for reducing the pressure inside the frame (inside the hollow fiber membrane) of the degassing module 94. By reducing the pressure, the dissolved gas dissolved in the coating material supplied to the inside of the frame is removed (degassing).

[0091] In addition, the pressure sensor S3 measures the pressure of the suction line 97 between the vacuum pump 98 and the degassing module 94 .

[0092] It should be noted that in the paint supply passage 72, a first flow meter FM1 is arranged at a position downstream of the degassing module 94 and upstream of the AOPR 92. The first flow meter FM1 measures the flow rate of the paint fed to the AOPR 92 and sends the measurement result to the control unit 100. The first flow meter FM1 is a non-contact type flow meter such as an ultrasonic type, an optical type, an electromagnetic type, a thermal type, etc., which has no moving parts, so the first flow meter FM1 is set outside the paint supply passage 72. It should be noted that the first flow meter FM1 may also use a flow meter with a moving part.

[0093] Here, when the first flow meter FM1 is an optical type, at least the portion of the paint supply passage 72 where the flow rate is measured by the first flow meter FM1 is set to be transparent. However, when the first flow meter FM1 is an ultrasonic type other than an optical type, at least the portion of the paint supply passage 72 where the flow rate is measured by the first flow meter FM1 does not need to be set to be transparent.

[0094] In addition, in the paint supply passage 72, a pressure sensor S4 is arranged at a position downstream of the first flow meter FM1 and upstream of the AOPR 92. In addition, in the paint supply passage 72, a pressure sensor S5 is arranged at a position downstream of the AOPR 92 and upstream of the three-way valve 77 and the orifice 96. The pressure sensor S4 measures the supply pressure of the paint to the AOPR 92 and sends the measurement result to the control unit 100. In addition, the pressure sensor S5 measures the pressure of the paint sprayed from the AOPR 92 and sends the measurement result to the control unit 100.

[0095] In this way, by using the pressure sensors S4 and S5 to measure the pressure of the paint on the upstream and downstream sides of the AOPR 92, it is possible to accurately measure the estimated pressure of the AOPR 92. It should be noted that the estimated pressure of the AOPR 92 can be set to the average of the pressure value of the pressure sensor S4 and the pressure value of the pressure sensor S5, or to the pressure value of either one of them.

[0096] It should be noted that the pressure sensor S4 is preferably provided in the paint supply mechanism 70, but a configuration in which the pressure sensor S4 is omitted may also be adopted. In addition, the pressure sensor S4 may be provided on the coating head unit 50 side or on the second rotating arm 25 side (robot arm R1 side). In addition, the pressure sensor S4 may also be provided at a position upstream of the first flow meter FM1.

[0097] In addition, in the return flow path 73, a pressure sensor S6 is arranged at a position downstream of the three-way valve 79 and upstream of the secondary side proportional control valve 93. In addition, in the return flow path 73, a pressure sensor S7 is arranged further downstream of a flow meter FM2 (described later) downstream of the secondary side proportional control valve 93. The pressure sensor S6 measures the supply pressure of the paint to the secondary side proportional control valve 93, and sends the measurement result to the control unit 100. In addition, the pressure sensor S7 measures the pressure of the paint ejected from the secondary side proportional control valve 93 (that is, the supply pressure of the paint to the suction pump 91), and sends the measurement result to the control unit 100.

[0098] In this way, by measuring the pressure of the paint on the upstream and downstream sides of the secondary-side proportional control valve 93 using the pressure sensors S6 and S7, it is possible to accurately measure the estimated pressure of the secondary-side proportional control valve 93. It should be noted that the estimated pressure of the secondary-side proportional control valve 93 may be set to the average value of the pressure value of the pressure sensor S6 and the pressure value of the pressure sensor S7, or to the pressure value of either one of them.

[0099] In addition, a pressure sensor may be disposed in the return flow path 73 at a position downstream of the secondary-side proportional control valve 93 and upstream of the flow meter FM2 .

[0100] In addition, in the return flow path 73, a second flow meter FM2 is arranged at a position downstream of the secondary side proportional control valve 93. The second flow meter FM2 measures the flow rate of the paint fed to the suction pump 91, and sends its measurement result to the control unit 100. Since the second flow meter FM2 is also a non-contact type flow meter such as an ultrasonic type, an optical type, an electromagnetic type, a thermal type, etc. without a movable part, the detailed description thereof is omitted. It should be noted that the second flow meter FM2 may also use a flow meter with a movable part.

[0101] A pressure sensor S8 is disposed in the return flow path 73 downstream of the suction pump 91 and upstream of the switching valve 80. The pressure sensor S8 measures the pressure of the paint discharged from the suction pump 91 and transmits the measurement result to the control unit 100.

[0102] In this way, by measuring the pressure of the paint on the upstream and downstream sides of the suction pump 91 using the pressure sensors S7 and S8, it is possible to accurately measure the estimated pressure of the suction pump 91. It should be noted that the estimated pressure of the suction pump 91 may be set to the average value of the pressure value of the pressure sensor S7 and the pressure value of the pressure sensor S8, or to the pressure value of either one of them.

[0103] (1-8. Schematic Structure of Control Unit)

[0104] Next, a schematic configuration of the control unit 100 for controlling the operation of the painting robot 10 will be described. Fig.11 1 is a diagram showing a schematic structure of control centered on the control unit 100 of the painting robot 10. Fig.11 As shown, the control unit 100 mainly includes a main control unit 110, an arm control unit 120, a head control unit 130, a paint supply control unit 140, a control memory 150, a position sensor 300, and a tilt sensor 310. In addition, the painting robot 10 is connected to the image processing device 200 to form a painting robot system.

[0105] It should be noted that the main control unit 110, the arm control unit 120, the head control unit 130, the paint supply control unit 140 and the image processing unit 210 described later are composed of a CPU (Central Processing Unit), a storage unit (ROM (Read Only Memory), RAM (Random Access Memory), a non-volatile memory, etc.) and other elements. It should be noted that the image processing unit 210 may also use a GPU (Graphics Processing Unit) on the basis of or in place of a CPU having excellent image processing performance.

[0106] The main control unit 110 in the above-mentioned control structure is a part that sends specified control signals to the above-mentioned arm control unit 120, head control unit 130 and paint supply control unit 140, so that the motors (the first to sixth motors) of the robot arm R1, the various action parts of the paint supply mechanism 70 and the piezoelectric substrate 62 cooperate to perform painting on the painting object.

[0107] In addition, the arm control unit 120 is a part that controls the driving of each motor (first to sixth motor) of the robot arm R1. The arm control unit 120 has an arm memory 121, in which data (trajectory data) related to the trajectory of the painting head 53 created by robot teaching considering the coating width that can be coated by the painting head 53 and posture data related to the posture such as the inclination of the painting head 53 are stored.

[0108] Furthermore, in the arm control unit 120, the driving of each motor (the first to sixth motors) of the robot arm R1 is controlled based on the trajectory data and posture data stored in the arm memory 121 and the image processing of the image processing unit 210 described later. Through this control, the painting head 53 can pass through the desired position for performing painting at a desired speed and stop at a specified position. It should be noted that the arm memory 121 may be possessed by the painting robot 10, but it may also be that the arm memory 121 exists outside the painting robot 10, and information can be sent and received to the arm memory 121 by means of wired or wireless communication means.

[0109] In addition, the head control unit 130 is a part that controls the movement of the piezoelectric substrate 62 in the coating head unit 50 based on the image processing of the image processing device 200. When the head control unit 130 reaches a specified position in the trajectory data according to a mechanism for detecting a position such as a position sensor 300 and an inclination sensor 310 described later, the spraying of the paint is controlled based on the allocated coating data corresponding to the position. It should be noted that in this case, the driving frequency of the piezoelectric substrate 62 is controlled to control the number of points (the number of droplets) sprayed from the nozzle 54, or the voltage applied to the piezoelectric substrate 62 is controlled to control the size of the droplets sprayed from the nozzle 54, so that the film thickness of the vehicle is uniform.

[0110] In addition, the paint supply control unit 140 is a part that controls the supply of paint to the coating head 53. Specifically, it controls the operation of each operating part such as the supply pump 90, the suction pump 91, the AOPR 92, the secondary side proportional control valve 93, the vacuum pump 98, the three-way valves 77, 79, the opening and closing valve 78, and the switching valve 80 in the paint supply mechanism 70. At this time, preferably, the paint supply control unit 140 controls the operation of the operating parts such as the pumps and valves so that the paint is supplied to the coating head 53 at a constant pressure. However, it is also possible that the paint supply control unit 140 can control the operation of the operating parts such as the pumps and valves so that the paint is supplied to the coating head 53 at a constant flow rate.

[0111] Here, the coating material supply control unit 140 can access the control memory 150 , and through this access, can read out an appropriate pressure setting value stored in the control memory 150 .

[0112] In addition, the position sensor 300 is a sensor for detecting the current position of the coating head 53. As the position sensor 300, a rotary encoder, a resolver, a laser sensor or other various sensors can be used. In addition, the tilt sensor 310 is a sensor for detecting the tilt angle of the coating head 53, corresponding to the angle detection mechanism. As the tilt sensor 310, for example, a gyro sensor, an acceleration sensor, a tilt sensor or other various sensors can be used.

[0113] (2. About the experimental results)

[0114] based on Fig.12 The experimental results when the orifice 96 is provided in the paint supply passage 72 as described above will be described.

[0115] Fig.12 Graph showing the experimental results of the relationship between the flow rate and the pressure loss when the inner diameter of the orifice 96 is 0.75 mm, 1.0 mm, and 1.2 mm. Fig.12For example, regarding the pressure loss when the flow rate of the paint supply passage 72 is 50cc / min, when the inner diameter of the orifice 96 is 0.75mm, the first experimental result is 10KPa, and the second experimental result is 11KPa. In addition, under the same conditions, when the inner diameter of the orifice 96 is 1.0mm, the first experimental result is 3KPa, and the second experimental result is 2KPa. In addition, under the same conditions, when the inner diameter of the orifice 96 is 1.2mm, the first experimental result is 2KPa, and the second experimental result is 2KPa.

[0116] In addition, regarding the pressure loss when the flow rate of the paint supply passage 72 is 100cc / min, when the inner diameter of the orifice 96 is 0.75mm, the first experimental result is 27KPa, and the second experimental result is 27KPa. In addition, under the same conditions, when the inner diameter of the orifice 96 is 1.0mm, the first experimental result is 10KPa, and the second experimental result is 9KPa. In addition, under the same conditions, when the inner diameter of the orifice 96 is 1.2mm, the first experimental result is 5KPa, and the second experimental result is 6KPa.

[0117] In addition, regarding the pressure loss when the flow rate of the paint supply passage 72 is 150cc / min, when the inner diameter of the orifice 96 is 0.75mm, the first experimental result is 48KPa, and the second experimental result is 48KPa. In addition, under the same conditions, when the inner diameter of the orifice 96 is 1.0mm, the first experimental result is 17KPa, and the second experimental result is 17KPa. In addition, under the same conditions, when the inner diameter of the orifice 96 is 1.2mm, the first experimental result is 9KPa, and the second experimental result is 9KPa.

[0118] (3. About the effect)

[0119] The painting robot 10 constructed as described above includes: a painting head unit 50 having a painting head 53, wherein the painting head 53 has a plurality of nozzles 54 for spraying liquid droplets and a piezoelectric substrate 62 for squeezing liquid droplets from the nozzles 54 by driving; a robot arm R1, wherein the painting head unit 50 is mounted at the front end of the robot arm R1, and the robot arm R1 moves the painting head unit 50 to a desired position; and a paint supply mechanism 70, which is arranged across the robot arm R1 and the painting head unit 50. In addition, the paint supply mechanism 70 includes: a paint supply passage 72, which supplies paint to the coating head 53; a return flow passage 73, which is connected to the paint discharge side of the coating head 53 and recovers the paint that has not been sprayed from the coating head 53; an AOPR92 (pneumatic control valve), which is arranged in the paint supply passage 72 and can adjust the valve opening according to the controlled air pressure; a throttle hole 96 (boosting mechanism), which is arranged in the paint supply passage 72 at a position on the downstream side toward the coating head 53 side compared with the AOPR92 (pneumatic control valve) or at a position on the upstream side compared with the AOPR92 (pneumatic control valve), and increases the pressure of the paint supplied to the AOPR92 (pneumatic control valve).

[0120] With such a configuration, the paint flowing in the paint supply passage 72 can increase the pressure loss when flowing through the throttle hole 96 (pressurizing mechanism). Therefore, the paint supply pressure can be increased on the upstream side of the throttle hole 96 (pressurizing mechanism) of the paint supply passage 72. As a result, the ratio of the pressure change to the pressure value input to the paint can be reduced on the upstream side of the throttle hole 96 (pressurizing mechanism).

[0121] That is, in the absence of the throttle hole 96 (pressurizing mechanism), the flow rate of the paint will change due to a slight pressure change, and there is a risk that the coating quality will be reduced due to the deviation of the spray amount of the paint sprayed from the nozzle 54. However, as described above, due to the presence of the throttle hole 96 (pressurizing mechanism), even if some pressure changes occur at a position upstream of the throttle hole 96 (pressurizing mechanism) in the paint supply passage 72, it can be brought within a range that does not affect the coating quality, resulting in improved coating quality.

[0122] In addition, since the paint supply pressure can be increased at a position on the upstream side of the paint supply passage 72 compared to the throttle hole 96 (boosting mechanism), the AOPR 92 (air pressure valve) having an operable pressure range higher than that of a proportional control valve as an electrical device can be used. Therefore, the proportional control valve as an electrical device can be omitted. Therefore, the painting robot 10 can be configured to be suitable for an explosion-proof environment.

[0123] Furthermore, by using the AOPR92 (air pressure valve), the operable pressure range can be expanded for the pressure set by the user, compared with the case of using a proportional control valve which is an electric device.

[0124] In addition, in the present embodiment, a secondary side proportional control valve 93 (electrically operated valve) capable of adjusting the valve opening by electrical operation is provided in the return flow path 73. In such a configuration, in the paint circulation path 71, the AOPR 92 (pneumatic control valve) is arranged on the upstream side of the secondary side proportional control valve 93 (electrically operated valve). Therefore, the pressure on the input side (upstream side, primary side) of the secondary side proportional control valve 93 (electrically operated valve) can be stabilized, thereby facilitating the pressure control on the output side (downstream side, secondary side) of the secondary side proportional control valve 93 (electrically operated valve).

[0125] In addition, in the present embodiment, the pressure increasing mechanism is a throttle hole 96 whose inner diameter of the paint supply passage 72 is narrowed, and the throttle hole 96 can be Figure 8 or Fig. 9 As shown, it is composed of a single hole portion, or it can be Fig.10 As shown, the nozzle 54 is composed of a plurality of holes. In such a configuration, when the paint passes through the throttle hole 96, it passes through a single hole or a plurality of holes. Therefore, when passing through, shear stress can be applied to the paint, and the viscosity of the paint can be reduced. Therefore, the paint after passing through the throttle hole 96 can be ejected from the nozzle 54 well, and the fluidity of the paint that has not been ejected from the nozzle 54 can be improved when it returns via the return flow path 73.

[0126] In addition, in the present embodiment, the boosting mechanism can be a removal filter for removing foreign matter contained in the paint flowing in the paint supply passage 72. In such a configuration, the paint passes through a plurality of holes in the removal filter. Therefore, when passing through, shear stress can be applied to the paint, and the viscosity of the paint can be reduced. Therefore, the paint after passing through the removal filter can be ejected from the nozzle 54 well, and the fluidity of the paint that has not been ejected from the nozzle 54 can be improved when it returns via the return flow path 73.

[0127] In addition, in the present embodiment, the paint supply mechanism 70 is provided with a bypass flow path 74, which connects the paint supply path 72 and the return flow path 73 and allows the paint to flow in parallel with the coating head 53, and the throttling hole 96 (boosting mechanism) is arranged in the paint supply path 72 at a position closer to the upstream side than the bypass flow path 74.

[0128] In such a configuration, since the orifice 96 (pressurizing mechanism) is provided at a position on the upstream side of the paint supply passage 72 compared to the bypass flow path 74, the paint not ejected from the coating head 53 also passes through the orifice 96 (pressurizing mechanism). Therefore, the viscosity of the paint can be reduced when passing through the orifice 96 (pressurizing mechanism). Therefore, by allowing the paint not ejected from the coating head 53 to circulate through the bypass flow path 74 and pass through the orifice 96 (pressurizing mechanism), the viscosity of the paint can be reduced well.

[0129] In addition, in the present embodiment, the throttle hole 96 can also be configured to be able to adjust the opening of the flow path for the paint to flow. In such a configuration, since the throttle hole 96 can adjust the opening of the flow path, it is possible to increase the opening of the throttle hole 96 when cleaning the paint supply passage 72, etc., thereby improving the cleaning performance. In addition, by adjusting the opening of the throttle hole 96, the operability of the AOPR 92 (pneumatic control valve) can be adjusted to a good range.

[0130] (4. Regarding Modifications)

[0131] Although one embodiment of the present invention has been described above, the present invention can be modified in various ways other than the above embodiment. Modifications will be described below.

[0132] In the above embodiment, the configuration including the pressure sensors S1 to S8 and the first flow meter FM1 and the second flow meter FM2 is adopted. However, when the first flow meter FM1 and the second flow meter FM2 are provided, at least one of the pressure sensors S1 to S8 may be omitted, and when the pressure sensors S1 to S8 are provided, at least one of the first flow meter FM1 and the second flow meter FM2 may be omitted.

[0133] In the above embodiment, the orifice 96 is provided in the paint supply passage 72 upstream of the three-way valve 77. However, the orifice 96 may be provided in the paint supply passage 72 downstream of the three-way valve 77 and upstream of the coating head 53.

[0134] Furthermore, in the above-described embodiment, the orifice 96 is provided on the downstream side of the AOPR 92 in the paint supply passage 72. However, when the pressure range of the AOPR 92 is not so high compared to the secondary-side proportional control valve 93, or when there is a portion other than the orifice 96 where pressure loss occurs, a configuration in which the orifice 96 is omitted may be adopted.

Claims

1. A painting robot, characterized in that: The painting robot performs painting on a vehicle and has: A coating head unit including a coating head including a plurality of nozzles for ejecting liquid droplets and a piezoelectric substrate for extruding the liquid droplets from the nozzles by driving; a robot arm, the coating head unit being mounted at a front end of the robot arm, and the robot arm moving the coating head unit to a desired position; and A paint supply mechanism is arranged across the robot arm and the coating head unit, The coating material supply mechanism comprises: a paint supply passage that supplies paint to the coating head; A return flow path connected to the paint discharge side of the coating head to recover the paint that has not been sprayed from the nozzle; A pneumatic control valve, which is provided in the paint supply passage and can adjust the valve opening according to the controlled air pressure; as well as A pressure increasing mechanism is provided in the paint supply passage at a position downstream of the air control valve toward the coating head or upstream of the air control valve to increase the pressure of the paint supplied to the air control valve.

2. The painting robot according to claim 1, characterized in that: The return flow path is provided with an electrically operated valve, which can adjust the valve opening by electrical operation.

3. The painting robot according to claim 1, characterized in that: The pressure increasing mechanism is a throttle hole whose inner diameter of the paint supply passage is narrowed. The throttle hole is composed of a single hole portion or a plurality of hole portions.

4. The painting robot according to claim 1, characterized in that: The pressure increasing mechanism is a removal filter that removes foreign matter contained in the paint flowing in the paint supply passage.

5. The painting robot according to claim 1, characterized in that: The paint supply mechanism is provided with a bypass flow path that connects the paint supply passage and the return flow path and allows the paint to flow in parallel with the coating head. The pressure increasing mechanism is provided on the upstream side of the bypass flow path in the coating material supply passage.

6. The painting robot according to claim 3, characterized in that: The throttle hole can adjust the opening of the flow path through which the coating material flows.

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