Coating robot and coating method

Abstract

The present disclosure provides a coating robot and a coating method capable of improving coating quality, in particular, at the end of a coating film by suppressing overflow of a coating material in a nozzle. The painting robot (10) includes: a painting head unit (50) including a plurality of nozzles (54) that eject liquid droplets and a painting head (53) of a piezoelectric substrate (62) that extrudes the liquid droplets from the nozzles (54); a robot arm (R1) having the coating head unit attached to the tip thereof and moving the coating head unit to a desired position; and a control unit (100) that includes a coating head control unit (130) that controls the operation of the piezoelectric substrate, and an arm control unit (120) that controls the operation of the robot arm, the coating head control unit controlling the operation of the piezoelectric substrate. The amount of deformation of the piezoelectric substrate when an end coating region (CR2) on the end side of the coating region (CR) is coated is made smaller than the amount of deformation of the piezoelectric substrate when a normal coating region (CR1) is coated.

Description

Technical Field

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

[0002] In the painting line of vehicles such as automobiles, robot painting using robots has become the mainstream. As an example of the structure related to the robot painting, for example, the following structure is disclosed in Patent Document 1.

[0003] The painting robot disclosed in the patent document 1 discloses control of the coating film thickness in the overlapping coating area. Specifically, the coating control unit performs coating on the divided coating surface formed by each scan of the nozzle head unit 50 to form a normal coating area and an overlapping coating area, wherein the normal coating area is an area that is painted in a manner to form a target coating film thickness, and the overlapping coating area is an area that is painted in a state where the amount of paint sprayed is reduced compared to the normal coating area. And, when performing this coating, the coating is performed by mixing the overlapping coating areas in the previous and next scans so that the coating film thickness of the mixed overlapping coating area becomes the target coating film thickness.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 7285827 Summary of the invention

[0007] However, if the paint overflows around the nozzle on the nozzle forming surface, the overflowed paint will adhere to the paint sprayed from the nozzle, resulting in the paint being sprayed in a state of enlarged droplets. Therefore, larger droplets than the size of the droplets expected to land on the coating area land.

[0008] If such droplets of a larger size than expected land, particularly when forming the edge (outline) of the coating film, the outline cannot be formed as clear as expected, and the outline is formed in a state where unevenness between the landed droplets is obvious.

[0009] In addition, as time goes by, the overflowed paint will solidify due to drying, and a film formed by solidification will begin to form on the nozzle forming surface. In this case, there is a situation where the paint is not sprayed at all, or even if the paint is sprayed, the opening area of ​​the nozzle is reduced due to the solidification of the paint, so that only small droplets can be sprayed.

[0010] In addition, there are cases where the ejection direction of droplets changes to an unexpected direction due to overflowing paint, and such abnormal ejection of droplets may also cause a risk of deteriorating the quality of the edge (profile) of the coating film when it is formed.

[0011] 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 and a painting method capable of improving the painting quality, particularly at the end of the coating film, by suppressing the overflow of the paint in the nozzle.

[0012] In order to solve the above-mentioned problems, according to a first aspect of the present invention, a painting robot is provided, characterized in that the painting robot performs painting on a painting area of ​​a vehicle, comprising: a painting head unit having a painting head, the painting head having a plurality of nozzles for spraying droplets and a piezoelectric substrate for squeezing droplets from the nozzles by driving; a robot arm having the painting head unit mounted at the front end and moving the painting head unit to a desired position; and a control unit having a painting head control unit for controlling the movement of the piezoelectric substrate of the painting head, and an arm control unit for controlling the movement of the robot arm, the painting head control unit controlling the movement of the piezoelectric substrate so that the deformation of the piezoelectric substrate when painting an end painting area on the end side of the painting area is smaller than the deformation of the piezoelectric substrate when painting a normal painting area on the inner side of the painting area than the end side.

[0013] Furthermore, in the above invention, it is preferable that the driving frequency of the piezoelectric substrate when painting the normal painting area is set to a frequency at which the resonance of the piezoelectric substrate becomes larger than the driving frequency of the piezoelectric substrate when painting the end painting area.

[0014] Furthermore, in any of the above inventions, preferably, the coating head control unit controls the driving of the piezoelectric substrate so that the amount of deformation of the piezoelectric substrate when coating the end coating region increases as the distance from the contour of the end coating region increases.

[0015] In addition, in any one of the above-mentioned inventions or their combination, it is preferred that the arm control unit controls the movement of the robot arm when painting the painting area so that the end painting area around the periphery of the painting area moves, and after the painting of the end painting area is completed, the normal painting area surrounded by the end painting area is painted, and the painting head control unit controls the movement of the piezoelectric substrate so that the deformation of the piezoelectric substrate when painting the end painting area is smaller than the deformation of the piezoelectric substrate when painting the normal painting area.

[0016] Furthermore, in any one of the above inventions or a combination thereof, preferably, in the coating head, a convex portion or a concave portion is formed around the opening portion of the nozzle in a nozzle forming surface exposed at the opening portion of the nozzle.

[0017] In addition, in any one of the above-mentioned inventions or a combination thereof, it is preferred that the coating head control unit is controlled in a manner that applies a driving waveform of a suction-extrusion-suction form relative to the piezoelectric substrate, wherein the suction-extrusion-suction form refers to sucking the paint into the interior of the nozzle, then extruding it, and then sucking the paint again after extrusion.

[0018] In addition, according to a second aspect of the present invention, a painting method is provided, characterized in that the painting method uses a painting robot to paint a painting area of ​​a vehicle, and the painting robot includes: a painting head unit with a painting head, the painting head having a plurality of nozzles for spraying droplets and a piezoelectric substrate for squeezing droplets from the nozzles by driving; a robot arm, which has a painting head unit installed at the front end and moves the painting head unit to a desired position; and a control unit, which has a painting head control unit for controlling the movement of the piezoelectric substrate of the painting head, and a control unit The arm control unit for controlling the movement of the robot arm, the painting method comprises: an end painting step, in which the movement of the piezoelectric substrate is controlled by a painting head control unit so that the deformation of the piezoelectric substrate when painting the end painting area on the end side of the painting area is smaller than the deformation of the piezoelectric substrate when painting the normal painting area on the inner side of the painting area; and an inner side painting step, in which, after the end painting step, the piezoelectric substrate is moved in a state in which the deformation of the piezoelectric substrate is larger than that in the end painting step, so as to paint the normal painting area.

[0019] Effects of the Invention

[0020] According to the present invention, it is possible to provide a painting robot and a painting method that can improve the painting quality, particularly at the end of the coating film, by suppressing the overflow of the paint in the nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram showing the overall structure of a painting robot according to one embodiment of the present invention.

[0022] Figure 2 It is shown from the front view Figure 1 FIG. 1 is a diagram showing a state of a nozzle forming a surface for ejecting paint in a painting head unit of a painting robot.

[0023] 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.

[0024] Figure 4 It is shown in Figure 1 A cross-sectional view of the structure near the nozzle pressurizing chamber in the painting robot shown.

[0025] Figure 5 is shown with Figure 2The illustrated coating head unit 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.

[0026] Figure 6 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.

[0027] Figure 7 It is shown that Figure 1 The diagram shows a schematic configuration of the control aspect of the painting robot centered on the control unit.

[0028] Figure 8 It is shown that the use Figure 1 A diagram of the painting area formed by the painting robot is shown.

[0029] Fig. 9 is shown for forming Figure 8 FIG. 2 is a diagram showing an example of painting data for division of a painting area.

[0030] Fig.10 It is shown in the formation Figure 8 The cross-sectional view of the coating area shown is a state in which the leaked paint adheres to the periphery of the nozzle due to paint overflow.

[0031] Fig.11 is shown in the ejection for forming Figure 8 The drawing shows a state in which the end portion of the coating area and the vicinity of the coating area are coated using a conventional droplet ejection method when droplets are ejected in the coating area.

[0032] Fig.12 is schematically shown in the ejection for forming Figure 8 The diagram shows the size of the droplets to be ejected for each pixel near the end coating data area when the droplets are ejected in the coating area.

[0033] Fig.13 This is a diagram showing a state in which the vicinity of the end coating region of the coating surface is coated by the liquid droplet discharge method according to the present embodiment.

[0034] Fig.14 It is schematically shown Fig.12 FIG. 2 is a diagram showing a modified example of the state in which the size of the droplets to be ejected is set for each pixel.

[0035] Description of Reference Numerals

[0036] 10. Painting Robot

[0037] 11. Painting Robot System

[0038] 20 Robot body

[0039] 21 Abutment

[0040] 22a First rotation axis

[0041] 22b Second rotation axis

[0042] 22c Third rotation axis

[0043] 22d Fourth rotation axis

[0044] 22e Fifth axis of rotation

[0045] 22f Sixth rotation axis

[0046] 24 First rotating arm

[0047] 25 Second rotating arm

[0048] 26 Rotating arm

[0049] 27 Wrist

[0050] 50 coating head unit

[0051] 52 Nozzle forming surface

[0052] 53 Painting Head

[0053] 54 Nozzle

[0054] 55 nozzle rows

[0055] 55A Nozzle row 1

[0056] 55B Second nozzle row

[0057] 59 Nozzle pressurization chamber

[0058] 59a Nozzle supply flow path

[0059] 62 Piezoelectric substrate

[0060] 63a Piezoelectric ceramic layer

[0061] 63b Piezoelectric ceramic layer

[0062] 64 Common electrode

[0063] 65 independent electrodes

[0064] 70 Paint supply mechanism

[0065] 71 Paint circulation path

[0066] 72 Paint supply passage

[0067] 73 Return flow

[0068] 74 Bypass flow path

[0069] 75 External supply channel

[0070] 76 Bubble removal parts

[0071] 77 Three-way valve

[0072] 78 On / Off Valve

[0073] 79 Three-way valve

[0074] 80 Switching valve

[0075] 81 Exhaust channel

[0076] 90 supply pump (corresponding to the paint supply mechanism)

[0077] 91 Suction pump (corresponding to paint recovery mechanism)

[0078] 92 first paint regulator (corresponding to the first regulating valve)

[0079] 93 second paint regulator (corresponding to the second regulating valve)

[0080] 94 Degassing module

[0081] 95 Remove filter

[0082] 96 Suction line

[0083] 97 Vacuum Pump

[0084] 100 Control Department

[0085] 110 Main control unit

[0086] 120 Arm control unit

[0087] 130 Head control unit

[0088] 140 Paint supply control unit

[0089] 150 Control memory

[0090] 200 Image processing device

[0091] 210 Image Processing Department

[0092] 220 Memory

[0093] 300 Position Sensor

[0094] 310 Tilt Sensor

[0095] CR painting area

[0096] CR1 Normal painting area

[0097] CR2 End coating area

[0098] CR3 Profile

[0099] D1 Division of coating data

[0100] DR1 Normal coating data area

[0101] DR2 End coating data area

[0102] FM1 First Flow Meter

[0103] FM2 Second flow meter

[0104] P1 Paint leakage

[0105] P2 Spraying droplets

[0106] PS coating path

[0107] R1 Robotic Arm

[0108] S1~S8 Pressure Sensor DETAILED DESCRIPTION

[0109] 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.

[0110] 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 production 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.

[0111] However, the coating film formed by coating with the coating robot 10 is not only a coating film that provides surface protection and aesthetics, but can also be formed by spraying a functional liquid having a certain function such as an adhesive.

[0112] 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.

[0113] (1-1. Overall structure of a spray-type vehicle painting robot)

[0114] 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.

[0115] (1-2. About the robot body)

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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 .

[0121] (1-3. About the coating head unit)

[0122] 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 in which nozzles 54 are arranged in a direction inclined relative to the long side direction of the coating head unit 50 are provided on the nozzle forming surface 52. 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.

[0123] 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.

[0124] In addition, if Figure 2 As 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.

[0125] It should be noted that the paint is supplied through the paint supply passage 72 (see Figure 6), the nozzle supply flow path 59a in the coating head 53, or other supply flow paths Figure 4 The coating material is supplied to the nozzle pressurizing chamber 59 shown in the figure, and the nozzle 54 is formed at a predetermined position (for example, the bottom surface) of the nozzle pressurizing chamber 59. In addition, the coating material not ejected from the nozzle 54 is discharged through the discharge flow path (not shown) in the coating head 53 connected to the nozzle pressurizing chamber 59. It should be noted that the discharge flow path in the coating head 53 is connected to the return flow path 73 of the coating material supply mechanism 70 described later.

[0126] 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 flow path including the nozzle supply flow path 59a in the coating head 53 and the nozzle pressurizing chamber 59. In addition, the paint not ejected from the nozzle 54 is returned from the nozzle pressurizing chamber 59 via the discharge flow path in the coating head 53 to the return flow path 73 of the paint supply mechanism 70 described later.

[0127] In addition, if Figure 4 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, which are 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.

[0128] In addition, if Figure 4 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.

[0129] It should be noted that in Figure 4In 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 4 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.

[0130] (1-4. Other configurations of the coating head unit)

[0131] Next, other configurations of the coating head unit 50 will be described. Figure 5 FIG. 5 is a top view showing the structure of the nozzle forming surface 52 of another coating head unit 50. Figure 5 As shown in FIG. 1 , a plurality of nozzles 54 may be arranged along the short side direction (width direction; Y direction) of the coating head 53 to form a nozzle row 55. Figure 5 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.

[0132] In addition, when using Figure 5 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 , if the nozzle array 55 is tilted at an angle α relative to the main scanning direction, the long side direction of the coating head 53 can be tilted at an angle α relative to the main scanning direction of the coating head 53. In such a tilt, 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.

[0133] (1-5. About paint supply mechanism)

[0134] Next, the coating material supply mechanism 70 will be described. Figure 6 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, a first paint regulator 92, a second paint regulator 93, a degassing module 94, a removal filter 95, pressure sensors S1 to S8, a first flow meter FM1, and a second flow meter FM2 as main components.

[0135] The paint circulation path 71 is a flow path for circulating the paint, and includes 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 supply path in the coating head 53.

[0136] The return flow path 73 is connected to the discharge flow path in 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 .

[0137] 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.

[0138] 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 .

[0139] 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.

[0140] In addition, the paint supply passage 72 is connected to the three-way valve 77 on the downstream side compared to the first paint regulator 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.

[0141] 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.

[0142] In addition, a three-way valve 79 is connected to the downstream side of the bypass flow path 74 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) of the return flow path 73. 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.

[0143] In addition, a switching valve 80 is arranged 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 path 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 path 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 path 81.

[0144] 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 .

[0145] 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.

[0146] 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 toward the upstream side compared to 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.

[0147] In addition, in the paint supply passage 72, a first paint regulator 92 is arranged on the downstream side compared to the supply pump 90. The first paint regulator 92 alleviates the pulsation in the supply pump 90 and supplies the paint at a constant pressure. It should be noted that the first paint regulator 92 corresponds to the regulating valve and the first regulating valve. The first paint regulator 92 can adjust the opening according to the control air pressure and the electrical signal through the control of the control unit 100 described later. Thus, the pressure on the downstream side of the first paint regulator 92 can be controlled to a specified pressure setting value corresponding to the pressure on the upstream side of the first paint regulator 92.

[0148] In addition, in the return flow path 73, a second paint regulator 93 is arranged on the upstream side compared to the suction pump 91. The second paint regulator 93 alleviates the pulsation in the suction pump 91 and sucks the paint at a constant pressure (negative pressure). The second paint regulator 93 can also adjust the opening corresponding to the control air pressure and electrical signal through the control of the control unit 100 described later. Thus, the pressure on the upstream side of the second paint regulator 93 can be controlled to a specified pressure setting value corresponding to the pressure on the downstream side of the second paint regulator 93.

[0149] In addition, in the paint supply passage 72, a degassing module 94 is arranged on the downstream side of the supply pump 90 and on the upstream side of the first paint regulator 92. The degassing module 94 is a component that is arranged on the downstream side of the paint supply passage 72 compared to the removal filter 95 described later and is used to remove (degas) dissolved gas dissolved in the paint.

[0150] In addition, a removal filter 95 is arranged in the paint supply passage 72 on the upstream side of the degassing module 94 and on the downstream side 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 painting head 53 in normal operation.

[0151] 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 on the downstream side of the supply pump 90 and on the upstream side 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.

[0152] 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 value 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 water head pressure difference described later.

[0153] In addition, the degassing module 94 is connected to a vacuum pump 97 via a suction line 96. As described above, the vacuum pump 97 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).

[0154] In addition, the pressure sensor S3 measures the pressure of the suction line 96 between the vacuum pump 97 and the degassing module 94 .

[0155] It should be noted that, in the paint supply passage 72, a first flow meter FM1 is arranged on the downstream side compared to the degassing module 94 and on the upstream side compared to the first paint regulator 92. The first flow meter FM1 measures the flow rate of the paint fed to the first paint regulator 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.

[0156] In addition, in the paint supply passage 72, a pressure sensor S4 is arranged on the downstream side compared with the first flow meter FM1 and on the upstream side compared with the first paint regulator 92. In addition, in the paint supply passage 72, a pressure sensor S5 is arranged on the downstream side compared with the first paint regulator 92 and on the upstream side compared with the three-way valve 77. The pressure sensor S4 measures the supply pressure of the paint to the first paint regulator 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 first paint regulator 92, and sends the measurement result to the control unit 100.

[0157] In this way, by measuring the pressure of the paint on the upstream and downstream sides of the first paint regulator 92 using the pressure sensors S4 and S5, it is possible to measure the estimated pressure of the first paint regulator 92 with high accuracy. It should be noted that the estimated pressure of the first paint regulator 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.

[0158] 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 on the upstream side compared to the first flow meter FM1.

[0159] In addition, in the return flow path 73, a pressure sensor S6 is arranged on the downstream side of the three-way valve 79 and on the upstream side of the second paint regulator 93. In addition, in the return flow path 73, a pressure sensor S7 is arranged on the downstream side of the flow meter FM2 (described later) on the downstream side of the second paint regulator 93. The pressure sensor S6 measures the supply pressure of the paint to the second paint regulator 93, and sends its measurement result to the control unit 100. In addition, the pressure sensor S7 measures the pressure of the paint ejected from the second paint regulator 93 (that is, the supply pressure of the paint to the suction pump 91), and sends its measurement result to the control unit 100.

[0160] In this way, by measuring the pressure of the paint on the upstream and downstream sides of the second paint regulator 93 using the pressure sensors S6 and S7, it is possible to accurately measure the estimated pressure of the second paint regulator 93. It should be noted that the estimated pressure of the second paint regulator 93 can be set to the average 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.

[0161] It should be noted that, in the return flow path 73 , a pressure sensor may be disposed on the downstream side of the second paint regulator 93 and on the upstream side of the flow meter FM2 .

[0162] In addition, in the return flow path 73, a second flow meter FM2 is arranged on the downstream side of the second paint regulator 93. The second flow meter FM2 measures the flow rate of the paint sent 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 can also use a flow meter with a movable part.

[0163] In the return flow path 73 , a pressure sensor S8 is disposed 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 .

[0164] 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.

[0165] (1-8. Schematic Structure of Control Unit)

[0166] Next, a schematic configuration of the control unit 100 for controlling the operation of the painting robot 10 will be described. Figure 7 1 is a diagram showing a schematic structure of control centered on the control unit 100 of the painting robot 10. Figure 7 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 (reference numerals omitted).

[0167] 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.

[0168] 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.

[0169] 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 (not shown), in which data related to the trajectory of the painting head 53 (trajectory data) created by robot teaching taking into account the coating width that can be coated by the painting head 53 and posture data related to the posture of the painting head 53, such as the inclination, are stored.

[0170] Furthermore, in the arm control unit 120, the driving of each motor (first to sixth motor) of the robot arm R1 is controlled based on the trajectory data and posture data stored in the arm memory 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 can be installed in the painting robot 10, but the arm memory can also be provided outside the painting robot 10 (for example, Figure 7 The memory 220 shown in the figure) can send and receive information with respect to the arm memory by means of wired or wireless communication means.

[0171] 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 coating is controlled based on the divided coating data corresponding to the position. It should be noted that in this case, the number of points (the number of droplets) sprayed from the nozzle 54 is controlled by controlling the driving frequency of the piezoelectric substrate 62, or the deformation amount of the piezoelectric substrate 62 is controlled based on the driving frequency and / or voltage applied to the piezoelectric substrate 62 to control the size of the droplets sprayed from the nozzle 54, so that the film thickness of the vehicle is uniform.

[0172] It should be noted that, in the case where the droplet size is controlled by controlling the amount of deformation of the piezoelectric substrate 62 based on the driving frequency applied to the piezoelectric substrate 62, the droplet size is the largest when the piezoelectric substrate 62 is driven at a driving frequency that matches the natural vibration frequency of the piezoelectric substrate 62. Therefore, it is possible to control the droplet size in a manner that becomes smaller as the applied driving frequency deviates from the natural vibration frequency. In addition, in the case where the droplet size is controlled by controlling the amount of deformation of the piezoelectric substrate 62 based on the voltage applied to the piezoelectric substrate 62, it is possible to control the droplet size in a manner that the higher the voltage of the piezoelectric substrate 62, the larger the droplet size.

[0173] 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 first paint regulator 92, the second paint regulator 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.

[0174] Here, the coating material supply control unit 140 can access the control memory 150 , and through this access, can read the control-related data such as the pressure setting value stored in the control memory 150 .

[0175] 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. As the tilt sensor 310, for example, a gyro sensor, an acceleration sensor, a tilt sensor, or other various sensors can be used.

[0176] (2. Regarding droplet ejection control)

[0177] Next, the liquid droplets are ejected from the nozzle 54 of the coating head 53 so as to be Figure 8 The control when forming the coating area CR on the coating object shown in FIG. Figure 8 The image data corresponding to the painting region CR shown is generally such that the width of the painting region CR is sufficiently larger than the width of the painting head 53 .

[0178] When the width of the painting region CR is sufficiently larger than the width of the painting head 53 , the image processing device 200 creates divided painting data D1 obtained by dividing the image data into short strips corresponding to the width (painting path) that can be painted by the painting head 53 . Fig. 9 Executing the paint discharge based on the divided painting data D1 enables painting at each scanning time (each painting path) of the painting head unit 50 .

[0179] Since the divided painting data D1 is short as described above, the painting start position or the painting end position is usually located at the end side of the painting area. In addition, both ends of the arrangement direction of the divided painting data D1 are also located at the end side of the painting area.

[0180] Next, the data area (data area for forming a coating film with a normal film thickness) that is not located at the end side of the coating area but located inside the end side in the divided coating data D1 is set as the normal coating data area DR1. In addition, the data area corresponding to the part located at the end side of the coating area in the divided coating data D1 is set as the end coating data area DR2.

[0181] After creating such divided painting data D1, the main control unit 110 sends a control signal for executing painting to the arm control unit 120, the head control unit 130 and the paint supply control unit 140 based on the divided painting data D1. Then, the arm control unit 120 drives at least one of the motors built into the robot arm R1 at a predetermined driving speed so that the painting object can be painted. In addition, when the paint supply control unit 140 determines that the painting head unit 50 has reached a predetermined spatial position relative to the painting object through the position sensor 300 and the tilt sensor 310, it starts to spray paint from any nozzle 54 of the painting head unit 50.

[0182] At this time, the head control unit 130 controls the driving of the piezoelectric substrate 62 of each nozzle 54 so that the paint is sequentially ejected from the nozzle 54 that reaches the end of the coating object. Figure 8 The painted area CR is shown.

[0183] Here, in the above-mentioned painting area CR, a normal painting area CR1 formed by spraying paint corresponding to the normal painting data area DR1 and an end painting area CR2 formed by spraying paint corresponding to the end painting data area DR2 are formed for each painting path PS. The details (details of the control of the spraying of droplets) are described below.

[0184] (2-1. Details of Control of Droplet Ejection)

[0185] When ejecting droplets, in the normal coating data area DR1, it is determined whether to eject paint droplets from the nozzle 54 according to a predetermined film thickness, and the size of the paint droplets is determined when ejecting the paint.

[0186] For example, it is assumed that the size of the droplets can be adjusted in eight stages by adjusting the driving frequency and voltage of the piezoelectric substrate 62. In this case, in the normal coating area CR1 based on the normal coating data area DR1, in order to ensure sufficient thickness of the coating film, relatively large droplets are sprayed to form. Here, the smallest droplet is called droplet 1, the second smallest droplet is called droplet 2, and then, as the number increases, the droplet size increases, and the largest droplet is called droplet 8. In this case, for example, Fig. 9 In the case of painting based on the normal painting data area DR1, the whole is painted with droplets 6 to 8.

[0187] Therefore, when the coating head 53 is driven from the driving stop state, a relatively large pressure change occurs, especially inside the nozzle 54 corresponding to the piezoelectric substrate 62. Similarly, when the coating head 53 is stopped from the driving state, a relatively large pressure change occurs, especially inside the nozzle 54 corresponding to the piezoelectric substrate 62.

[0188] When such pressure fluctuation occurs, paint may overflow from the meniscus formed near the opening of the nozzle 54. Hereinafter, a portion (liquid droplet) formed around the nozzle 54 of the coating head 53 due to paint overflow is referred to as leaked paint P1. Fig.10 2 is a cross-sectional view showing a state in which the leaked paint P1 adheres to the periphery of the nozzle 54 due to the paint overflow. Fig.10As shown, when the leaked paint P1 is formed around the nozzle 54 on the nozzle forming surface 52 , there is a risk that the leaked paint P1 will adhere to (be drawn into) the ejection droplets P2 newly ejected from the nozzle 54 .

[0189] Then, the ejected droplets P2 are attached to the coating object in a state of becoming larger than the original droplet size. Therefore, in the coating area corresponding to the end coating data area DR2, in particular, the droplets larger than the expected droplet size land, resulting in a state where unevenness becomes noticeable.

[0190] Fig.11 1 is a diagram showing a state in which the coating area CR2 near the end of the coating surface (coating area CR) is coated by a conventional droplet ejection method when the ejection droplet P2 is ejected. Fig.11 As shown, in the conventional droplet ejection method, due to the influence of pressure fluctuation, leaked paint P1 is formed near the nozzle 54, and the ejected droplet P2 is ejected in a state where the leaked paint P1 is attached (in a state of being rolled up), thereby forming a step-shaped contour CR3 instead of forming a clear contour. Therefore, the boundary quality of the end coating area CR2 of the coating area CR is degraded.

[0191] In addition, if the nozzle 54 cannot eject droplets due to the influence of the leaked paint P1, even if the nozzle 54 reaches the ejection start position where the droplets should be ejected, the droplets cannot be ejected. At this time, if a pressure that can break through the surface tension of the leaked paint P1 or the solidified film formed by drying can be applied to the paint, the droplets can be ejected from the nozzle 54. However, in this case, the leaked paint P1 or the broken film will hinder the ejection of the droplets. Therefore, in this case, droplets smaller than usual will be ejected, and there is a risk of failing to reach the predetermined film thickness and causing poor coating.

[0192] In addition, there are cases where the ejection direction of droplets is changed to an unexpected direction due to overflowing paint, and there is a risk that the quality of the edge (outline) of the coating will be reduced due to such abnormal ejection of droplets.

[0193] In contrast, in the present embodiment, when droplets are ejected based on the end painting data area DR2, the end painting data area DR2 is formed so that droplets of smaller size (eg, droplet 1 and droplet 2) are ejected compared to the case where droplets are ejected based on the normal painting data area DR1. Fig.12 2 is a diagram schematically showing the size of the droplets to be ejected near the end coating data area DR2 for each pixel. Fig.12As shown, the end painting data region DR2 is formed so that small-sized droplets such as droplets 1 and 2 are ejected for pixels that will become the outline CR3 of the painting region CR after the droplets land.

[0194] It should be noted that the end painting data area DR2 is a data area including the pixels at the endmost end corresponding to the contour CR3 after painting. It may be that only the pixels at the endmost end correspond to the end painting data area DR2, or it may be that the pixels from the pixels at the endmost end to several pixels inside thereof correspond to the end painting data area DR2.

[0195] In addition, in the end coating data area DR2, the end coating data area DR2 can also be formed by spraying large-sized droplets such as droplets 6 to 8 for pixels that will become the contour CR3 of the coating area CR after the droplets land, and at the same time spraying small-sized droplets such as droplets 1 to 2 in the area adjacent to the large-sized droplets.

[0196] Based on the divided painting data D1 having the end painting data area DR2 formed as described above, painting is performed in each painting path. Thus, in each painting path, at the beginning and the end of painting, the deformation amount (driving amount) of the piezoelectric substrate 62 is reduced so as to eject droplets of a smaller size than in the case of painting the normal painting data area DR1. Then, in this state, the end painting area CR2 (corresponding to the end painting step) of the painting area CR is formed.

[0197] Therefore, in particular, when the coating head 53 is driven from the stopped state, it is possible to suppress the increase of the pressure fluctuation inside the nozzle 54 associated with the piezoelectric substrate 62. Similarly, when the coating head 53 is stopped from the driven state, it is also possible to suppress the increase of the pressure fluctuation inside the nozzle 54 associated with the piezoelectric substrate 62.

[0198] Therefore, it is possible to suppress Fig.10 The leaked paint P1 is formed near the opening of the nozzle 54 as shown, thereby preventing the leaked paint P1 from being attached to (entangled in) the ejection droplets P2 newly ejected from the nozzle 54 .

[0199] It should be noted that after the end coating step is performed, the piezoelectric substrate 62 is operated while the deformation amount of the piezoelectric substrate 62 is greater than the deformation amount in the end coating step, and the normal coating area CR1 is coated (corresponding to the inner side coating step).

[0200] here, Fig.13 FIG. 2 shows a state where the end coating region CR2 near the coating region CR is coated using the droplet ejection method of this embodiment. Fig.13 As shown, in the droplet ejection method of this embodiment, Fig.11 Compared with the conventional droplet ejection method shown in the figure, the unevenness of the contour CR3 of the coating region CR is alleviated, and a clear contour is formed. Therefore, the boundary quality of the coating region CR2 at the end of the coating region CR can be improved.

[0201] It should be noted that, in order to further suppress the influence of pressure fluctuations, the head control unit 130 may control the driving of the piezoelectric substrate 62 in such a manner that the deformation amount of the piezoelectric substrate 62 when coating the end coating region CR2 increases as the contour CR3 away from the end coating region CR2 increases. Fig.14 This is shown in Fig.12 The different approach sets the state of the droplet size for each pixel. Fig.14 A state is shown in which the droplet size gradually increases starting from the droplet 1 as the droplet 1 moves away from the contour CR3.

[0202] (3. About the effect)

[0203] As described above, the painting robot 10 for painting the painting area CR of a vehicle comprises: a painting head unit 50 having a painting head 53, wherein the painting head 53 comprises a plurality of nozzles 54 for ejecting liquid droplets and a piezoelectric substrate 62 for squeezing liquid droplets from the nozzles 54 by driving; a robot arm R1, at the front end of which the painting head unit 50 is mounted, and the robot arm moves the painting head unit 50 to a desired position; and a control unit 100, which comprises a painting head control unit 130 for controlling the movement of the piezoelectric substrate 62 of the painting head 53, and an arm controller 120 for controlling the movement of the robot arm R1.

[0204] Furthermore, the head control unit 130 controls the movement of the piezoelectric substrate 62 so that the deformation of the piezoelectric substrate 62 when painting the end painting area CR2 on the end side of the painting area CR is smaller than the deformation of the piezoelectric substrate 62 when painting the normal painting area CR1 on the inner side of the end side of the painting area CR.

[0205] In this way, the head control unit 130 controls the action of the piezoelectric substrate 62 so that when the end coating area CR2 is coated with the timing corresponding to at least one of the coating start and coating end timings with large pressure fluctuations, the deformation amount of the piezoelectric substrate 62 is smaller than the deformation amount of the piezoelectric substrate 62 when the normal coating area CR1 inside the coating area CR is coated. Thus, when the end coating area CR2 is coated, the influence of the pressure fluctuation caused by the deformation of the piezoelectric substrate 62 can be reduced. Thus, the formation of the leaked paint P1 near the opening of the nozzle 54 can be suppressed. Therefore, the leaked paint P1 can be prevented from being attached (entangled) to the ejected droplets P2 newly ejected from the nozzle 54.

[0206] Furthermore, by suppressing the formation of leaked paint P1 near the opening of the nozzle 54, it is possible to prevent the paint P1 from leaking and the broken film from hindering the ejection of droplets. Thus, it is possible to prevent the nozzle 54 from reaching the ejection start position where droplets should be ejected but failing to eject droplets. In addition, it is possible to prevent the ejection of droplets smaller than usual from failing to reach the predetermined film thickness, resulting in poor coating.

[0207] In addition, it is possible to prevent abnormal discharge in which the discharge direction of droplets is changed to an unintended direction due to overflowing paint.

[0208] Furthermore, when the end coating region CR2 is coated, the size of the droplets ejected from the nozzle 54 can be made smaller than the size of the droplets when the normal coating region CR1 is coated. Thus, when the contour CR3 of the coating region CR is formed, the unevenness between the landed droplets can be reduced, thereby forming a clear contour with higher coating quality.

[0209] Furthermore, in the present embodiment, the driving frequency of the piezoelectric substrate 62 in the normal coating region CR1 can be set to a frequency at which the resonance of the piezoelectric substrate 62 is higher than the driving frequency of the piezoelectric substrate 62 when coating the end coating region CR2 .

[0210] By controlling the piezoelectric substrate 62 in this manner, the driving frequency of the piezoelectric substrate 62 when painting the end painting area CR2, corresponding to at least one of the start and end of painting, becomes a state deviated from the frequency (natural vibration frequency) at the time of resonance. Therefore, a state in which it is easier to drive in a direction that cancels out the vibration of the piezoelectric substrate 62 is achieved. Therefore, when painting the end painting area CR2, the size of the droplets ejected from the nozzle 54 can be reduced. Thus, when painting the end painting area CR2, it is possible to prevent the paint from overflowing from the nozzle 54 due to the increase in the pressure change of the paint. Therefore, it is possible to suppress the situation in which the leaked paint P1 adheres (is drawn into) the spray droplets P2 newly ejected from the nozzle 54.

[0211] Furthermore, when forming the contour CR3 of the coating region CR, the unevenness between the landed droplets can be reduced, and a clear contour with higher coating quality can be formed.

[0212] In the present embodiment, the head control unit 130 may control the driving of the piezoelectric substrate 62 so that the deformation amount of the piezoelectric substrate 62 when painting the end painting region CR2 increases as the contour away from the end painting region CR2 increases.

[0213] When the control is performed in this way, in the coating region CR, the size of the droplets ejected from the nozzle 54 increases as it moves from the end to the center. That is, by gradually reducing the size of the landing droplets as it moves toward the end of the formed coating film, an inclined portion can be formed on the coating film. Therefore, as the size of the landing droplets gradually decreases as it moves toward the end side of the coating film, the outflow of the paint to the end side can be suppressed, and the coating quality can be further improved.

[0214] (4. Regarding Modifications)

[0215] An embodiment of the present invention has been described above, but the present invention can be modified in various ways other than the above embodiment. Modifications will be described below.

[0216] In the above embodiment, it is also possible to replace Figure 8 When painting the painting area CR, the arm control unit 120 is used to move the end painting area around the periphery of the painting area CR. In addition, after the painting of the end painting area CR2 is completed, the movement of the robot arm R1 can be controlled so that the normal painting area CR1 surrounded by the end painting area CR2 is painted, and the head control unit 130 controls the movement of the piezoelectric substrate 62 in such a way that the deformation amount of the piezoelectric substrate 62 when painting the end painting area CR2 is smaller than the deformation amount of the piezoelectric substrate 62 when painting the normal painting area CR1.

[0217] By controlling the movement of the robot R1 in this way, when the end painting area CR2 is painted from the start of painting, the piezoelectric substrate 62 is painted with a smaller deformation amount than when the normal painting area CR1 on the inner side is painted. Therefore, when the contour CR3 of the painting area CR is painted, the size of the droplets ejected from the nozzle 54 can be reduced. Thus, when the end painting area CR2 is painted from the start of painting, the pressure fluctuation of the paint becomes large, which causes the paint to overflow from the nozzle 54.

[0218] Furthermore, when forming the contour CR3 of the coating region CR, the unevenness between the landed droplets can be reduced, and a clear contour with higher coating quality can be formed.

[0219] In addition, in the above-mentioned embodiment, divided painting data D1 is formed for each painting path PS, and there is an end painting data area DR2 for each divided painting data D1. However, at the beginning of painting in the first painting path PS in a series (multiple) painting paths PS used to form the painting area CR and at the end of painting in the last painting path PS, the pressure fluctuation is considered to be large. Therefore, the deformation amount of the piezoelectric substrate 62 in the end painting area CR2 at the beginning of painting in the first painting path PS in a series (multiple) painting paths PS used to form the painting area CR and at the end of painting in the last painting path PS can be suppressed.

[0220] In addition, the end painting region CR2 may be provided at a location where overlapping painting is performed in the adjacent painting paths PS, or the end painting region CR2 may not be provided.

[0221] In addition, in the above-mentioned embodiment, the nozzle forming surface 52 exposed by the nozzle 54 may be flat, but it may be configured to form a convex portion around the opening portion of the nozzle 54. In this case, the opening portion of the nozzle 54 may be protruded around the entire circumference, or a portion of the entire circumference (a single portion or a plurality of portions) may be protruded. In the case of such a configuration, for example, by extending the path length of the nozzle 54 or making the top of the dam-shaped portion slightly away from the opening portion of the nozzle 54, it is possible to suppress the formation of a leaking paint P1 near the opening portion of the nozzle 54 when the pressure changes.

[0222] In addition, the periphery of the opening portion of the nozzle 54 may be configured to form a concave portion that is depressed downward from the plane of the nozzle forming surface 52. In such a configuration, by forming the leaked paint P1 on the nozzle forming surface 52 below the depressed portion, it is possible to suppress the formation of the leaked paint P1 near the opening portion of the nozzle 54 when the pressure fluctuates.

[0223] In addition, in the above-mentioned embodiment, in order to reduce the influence of the vibration of the curved liquid surface of the paint existing in the nozzle 54, the head control unit 130 can be controlled in a manner of applying a driving waveform of the suction-extrusion-suction (Pull-Push-Pull) form to the piezoelectric substrate 62. The suction-extrusion-suction form means that after the paint is sucked into the nozzle 54 and extruded, the paint is sucked in again.

Claims

1. A painting robot, characterized in that: The painting robot performs painting on a painting area of ​​a vehicle, including: 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 having the coating head unit mounted at a front end thereof and moving the coating head unit to a desired position; and a control unit including a coating head control unit for controlling the movement of the piezoelectric substrate of the coating head and an arm control unit for controlling the movement of the robot arm, The coating head control unit controls the movement of the piezoelectric substrate so that the deformation of the piezoelectric substrate when coating the end coating area on the end side of the coating area is smaller than the deformation of the piezoelectric substrate when coating the normal coating area on the inner side of the coating area.

2. The painting robot according to claim 1, characterized in that: The driving frequency of the piezoelectric substrate when the normal coating region is coated is set to a frequency at which the resonance of the piezoelectric substrate becomes larger than the driving frequency of the piezoelectric substrate when the end coating region is coated.

3. The painting robot according to claim 1, characterized in that: The coating head control unit controls the driving of the piezoelectric substrate so that the amount of deformation of the piezoelectric substrate when coating the end coating region increases as the distance from the contour of the end coating region increases.

4. The painting robot according to claim 1, characterized in that: The arm control unit controls the movement of the robot arm when painting the painting area so that the robot arm moves around the end painting area located at the periphery of the painting area, and after the painting of the end painting area is completed, the normal painting area surrounded by the end painting area is painted. Furthermore, the coating head control unit controls the movement of the piezoelectric substrate so that the deformation amount of the piezoelectric substrate when coating the end coating area is smaller than the deformation amount of the piezoelectric substrate when coating the normal coating area.

5. The painting robot according to claim 1, characterized in that: In the coating head, a convex portion or a concave portion is formed around the opening portion of the nozzle on the nozzle forming surface where the opening portion of the nozzle is exposed.

6. The painting robot according to any one of claims 1 to 5, characterized in that: The coating head control unit controls the piezoelectric substrate by applying a driving waveform of a suction-extrusion-suction form, wherein the coating material is sucked into the nozzle, extruded, and then sucked again after extrusion.

7. A coating method, characterized in that: The painting method uses a painting robot to paint a painting area of ​​a vehicle, and the painting robot includes: 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 having the coating head unit mounted at a front end thereof and moving the coating head unit to a desired position; and a control unit including a coating head control unit for controlling the movement of the piezoelectric substrate of the coating head and an arm control unit for controlling the movement of the robot arm, The coating method comprises: an end coating step of controlling the movement of the piezoelectric substrate by the coating head control unit so that the deformation amount of the piezoelectric substrate when coating the end coating area on the end side of the coating area is smaller than the deformation amount of the piezoelectric substrate when coating the normal coating area on the inner side of the coating area; and The inner side coating step is performed after the end coating step by moving the piezoelectric substrate in a state where the amount of deformation of the piezoelectric substrate is larger than that in the end coating step, thereby coating the normal coating area.

Images