Coating robot and coating method

Abstract

To provide a coating robot and a coating method capable of improving coating quality especially at an end part of a coating film by suppressing coating leakage in a nozzle.SOLUTION: A coating robot 10 includes: a plurality of nozzles 54 discharging droplets; a coating head unit 50 provided with a coating head 53 provided with a piezoelectric substrate 62 for pushing the droplets out of the nozzles 54; a robot arm R1 fitting the coating head unit 50 to a leading end and moving the coating head unit 50 to a desired position; and a control part 100 which is provided with a head control part 130 controlling operation of the piezoelectric substrate 62 and an arm control part 120 controlling operation of the robot arm R1. The head control part 130 controls operation of the piezoelectric substrate 62 so as to reduce a deformation amount of the piezoelectric substrate 62 when coating an end part coating region CR2 on an end side of a coating region CR compared to a deformation amount of the piezoelectric substrate 62 when coating a normal coating region CR1.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] In painting lines for vehicles such as automobiles, robot painting using robots has become mainstream. As an example of a configuration related to this robot painting, for example, Patent Document 1 discloses the following configuration.

[0003] The painting robot disclosed in Patent Document 1 discloses a method for controlling the paint film thickness in the overlapping painting area. Specifically, the painting control unit performs painting so that a normal painting area where painting is performed to achieve a target paint film thickness and an overlapping painting area where painting is performed with a reduced amount of paint discharged compared to the normal painting area are formed on the divided painting surface formed by each scan of the nozzle head unit 50. During this painting, the overlapping painting areas from the previous and next scans are mixed, and painting is performed so that the paint film thickness in the overlapping painting area after mixing is the target paint film thickness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7285827 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when paint overflows around the nozzle on the nozzle forming surface, the overflowed paint adheres to the paint discharged from the nozzle, resulting in the droplets being discharged in a larger size, which results in the droplets landing on the coating area being larger than the size of the droplets that are expected to land on the coating area.

[0006] When droplets of a size larger than expected land, particularly when forming the edge (contour) of the coating film, the contour is not as sharp as expected, and the contour is formed with noticeable steps between the landed droplets.

[0007] In addition, the overflowing paint will dry and solidify over time, and begin to form a solidified film on the nozzle surface. In this case, either no paint will be ejected at all, or even if it is ejected, the nozzle opening area will be reduced by the solidification of the paint, and only small droplets may be ejected.

[0008] In addition, overflowing paint may cause the droplets to be ejected in an unintended direction, resulting in abnormal ejection. Such abnormal ejection of droplets may also result in a reduction in quality when forming the edge (contour) of the coating film.

[0009] The present invention has been made based on the above-mentioned circumstances, and aims to provide a painting robot and a painting method that can improve painting quality, particularly at the edges of the paint film, by suppressing paint overflow from the nozzle. [Means for solving the problem]

[0010] In order to solve the above problems, according to a first aspect of the present invention, there is provided a painting robot that paints a painting area of ​​a vehicle, comprising: a painting head unit having a painting head with a plurality of nozzles that eject droplets and a piezoelectric substrate that is driven to push the droplets out of the nozzles; a robot arm that has the painting head unit attached to its tip and moves the painting head unit to a desired position; a head control unit that controls the operation of the piezoelectric substrate of the painting head, and a control unit that includes an arm control unit that controls the operation of the robot arm, wherein the head control unit controls the operation of the piezoelectric substrate so that the amount of deformation of the piezoelectric substrate when painting an edge painting area on the edge side of the painting area is smaller than the amount of deformation of the piezoelectric substrate when painting a normal painting area that is more inward than the edge side of the painting area.

[0011] In addition, in the above-mentioned 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 is greater compared to the driving frequency of the piezoelectric substrate when painting the end painting area.

[0012] In addition, in any of the above-mentioned inventions, it is preferable that the head control unit controls the driving of the piezoelectric substrate so that the amount of deformation of the piezoelectric substrate when painting the end painting area increases as the substrate moves away from the contour of the end painting area.

[0013] Furthermore, in any of the above-mentioned inventions or combinations thereof, it is preferable that, when painting a painting area, the arm control unit controls the operation of the robot arm to rotate the end painting area located on the periphery of the painting area, and after painting of the end painting area is completed, to paint the normal painting area surrounded by the end painting area, and that the head control unit controls the operation of the piezoelectric substrate so that, when painting the end painting area, the deformation amount of the piezoelectric substrate is smaller than the deformation amount of the piezoelectric substrate when painting the normal painting area.

[0014] Furthermore, in any of the above-mentioned inventions or combinations thereof, it is preferable that in the painting head, a convex or concave portion is formed around the nozzle opening on the nozzle forming surface where the nozzle opening is exposed.

[0015] Furthermore, in any of the above-mentioned inventions or combinations thereof, it is preferable that the head control unit controls the piezoelectric substrate to apply a Pull-Push-Pull type drive waveform that draws paint into the nozzle, then pushes it out, and then draws the paint back in after the extrusion.

[0016] In addition, according to a second aspect of the present invention, there is provided a painting method for painting a painting area of ​​a vehicle using a painting robot, the painting robot comprising a painting head unit having a painting head equipped with a plurality of nozzles that eject droplets and a piezoelectric substrate that is driven to push the droplets out of the nozzles, a robot arm to which the painting head unit is attached and which moves the painting head unit to a desired position, and a control unit including a head control unit that controls the operation of the piezoelectric substrate of the painting head and an arm control unit that controls the operation of the robot arm, the painting method comprising: an edge painting step in which the head control unit controls the operation of the piezoelectric substrate so that the amount of deformation of the piezoelectric substrate when painting an edge painting area on the edge side of the painting area is smaller than the amount of deformation of the piezoelectric substrate when painting a normal painting area that is more inward than the edge side of the painting area, and an inner painting step, which follows the edge painting step, operates the piezoelectric substrate in a state in which the amount of deformation of the piezoelectric substrate is greater than in the edge painting step to paint the normal painting area. Effect of the Invention

[0017] According to the present invention, a painting robot and a painting method can be provided that are capable of improving the painting quality, particularly at the edges of the paint film, by suppressing paint overflow from the nozzle. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing an overall configuration of a painting robot according to an embodiment of the present invention; [Diagram 2] 2 is a front view of a nozzle forming surface for ejecting paint in a paint head unit of the painting robot shown in FIG. 1. FIG. [Diagram 3] 2 is a diagram showing a state in which a plurality of painting heads are arranged in a staggered manner in the painting robot shown in FIG. 1. [Figure 4] 2 is a cross-sectional view showing a configuration in the vicinity of a nozzle pressurizing chamber in the painting robot shown in FIG. 1. [Diagram 5]3 is a plan view showing the configuration of a nozzle forming surface of another paint head unit different from the paint head unit shown in FIG. 2. [Figure 6] 2 is a diagram showing a schematic configuration of a paint supply mechanism and the like provided in the painting robot shown in FIG. 1. [Figure 7] FIG. 2 is a diagram showing a schematic configuration of control centered on a control unit of the painting robot shown in FIG. [Figure 8] FIG. 2 is a diagram showing a painting area formed by using the painting robot shown in FIG. 1. [Figure 9] FIG. 9 is a diagram showing an example of divided painting data for forming the painting area shown in FIG. 8. [Figure 10] 9 is a cross-sectional view showing a state in which paint has leaked and adhered to the periphery of the nozzle due to paint overflow when forming the coating area shown in FIG. 8. FIG. [Figure 11] FIG. 9 is a diagram showing a state in which the vicinity of the edge coating region of the coating surface is coated by a current droplet discharging method when discharging droplets to form the coating region shown in FIG. 8. [Figure 12] 9 is a diagram showing a schematic diagram of the size of droplets to be discharged for each pixel in the vicinity of an end painting data region when droplets are discharged to form the painting region shown in FIG. 8. FIG. [Figure 13] FIG. 13 is a diagram showing a state in which the vicinity of an edge coating region of a coating surface has been coated using the droplet ejection method of the present embodiment. [Figure 14] 13 is a diagram showing a modification of the state shown in FIG. 12, in which the size of a droplet to be discharged is set for each pixel. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The painting robot 10 according to each embodiment of the present invention will be described below with reference to the drawings. In the following description, as necessary, the X direction is the longitudinal direction of the nozzle forming surface 52 (painting head 53), the X1 side is the right side in Fig. 2, and the X2 side is the left side in Fig. 2. The Y direction is the lateral direction (width direction) of the nozzle forming surface 52 (painting head 53), the Y1 side is the upper side of the paper in Fig. 2, and the Y2 side is the lower side of the paper in Fig. 2.

[0020] The painting robot 10 of this embodiment "paints" objects to be painted, such as vehicles or vehicle parts (hereinafter, vehicle parts that are part of a vehicle will also be described as vehicles) located on a painting line in an automobile manufacturing factory, and aims to form a paint film on the surface of the object to be painted to protect the surface and provide a beautiful appearance. Therefore, it is necessary to paint vehicles that move along the painting line at predetermined intervals within a certain time with the desired painting quality.

[0021] However, the coating film formed by painting with the painting robot 10 does not only provide surface protection and aesthetics, but may also be formed by discharging a functional liquid that has some function, such as an adhesive.

[0022] Furthermore, the painting robot 10 of this embodiment is capable of forming not only the above-mentioned coating film but also various designs and images on objects to be painted, such as vehicles and vehicle parts. Note that the objects to be painted are not limited to vehicles and vehicle parts, and may be any parts other than automobiles (for example, exterior parts of airplanes and trains) that require painting.

[0023] (1-1. Overall configuration of inkjet type vehicle painting robot) Fig. 1 is a schematic diagram showing the overall configuration of a painting robot 10 according to a first embodiment of the present invention. As shown in Fig. 1, the painting robot 10 mainly includes a robot body 20 and a painting head unit 50. The painting robot 10 shown in Fig. 1 is a six-axis vertical articulated robot as an example, but the painting robot 10 may be any type of robot, such as a vertical articulated type other than six axes, a horizontal articulated type, or an Cartesian robot.

[0024] (1-2. About the painting equipment itself) 1, the robot body 20 mainly comprises a base 21, first to sixth rotating shafts 22a to 22f, legs 23, a first rotating arm 24, a second rotating arm 25, a rotating arm 26, a wrist 27, and a motor (not shown) for driving these. Note that the portion from the legs 23 to the wrist 27 corresponds to the robot arm R1, but other portions such as the base 21 may also correspond to the robot arm R1.

[0025] Of these, the base 21 is a part that is installed on an installation site such as a floor surface, but the base 21 may be movable relative to the installation site. The legs 23 are parts that stand upward from the base 21, and are provided rotatable relative to the base 21 via a first rotating shaft 22a by driving a motor (first motor) not shown. The legs 23 may be configured not to rotate relative to the base 21.

[0026] A first rotating arm 24 is provided on the upper end of leg 23 so as to be rotatable via second rotating shaft 22b by driving a motor (second motor) not shown. Furthermore, a second rotating arm 25 is provided on the tip side of first rotating arm 24 so as to be rotatable via third rotating shaft 22c by driving a motor (third motor) not shown.

[0027] A rotating arm 26 is provided at the tip of the second rotating arm 25 so as to be rotatable around the central axis of the second rotating arm 25. The rotating arm 26 is rotatable via a fourth rotating shaft 22d by driving a motor (fourth motor) not shown. A wrist section 27 is provided at the tip of the rotating arm 26. The wrist section 27 is capable of rotating around a plurality of (for example, two) shaft sections in different directions. In FIG. 1, the rotating shafts capable of the rotating movement are the fifth rotating shaft 22e and the sixth rotating shaft 22f, respectively. This makes it possible to control the orientation of the painting head unit 50 with high precision. The number of shaft sections may be any number equal to or greater than two.

[0028] Further, a painting head unit 50 is attached to the wrist portion 27, but this painting head unit 50 may be provided so as to be detachable from the wrist portion 27.

[0029] (1-3. About the painting head unit) Next, the paint head unit 50 will be described. FIG. 2 is a diagram showing a front view of the nozzle forming surface 52 of the paint head unit 50 from which paint is ejected. As shown in FIG. 2, the paint head unit 50 includes a head cover (not shown), and various components are built into the head cover. As shown in FIG. 2, the nozzle forming surface 52 includes a plurality of nozzle rows 55 in which the nozzles 54 are arranged in a direction inclined with respect to the longitudinal direction of the paint head unit 50. In this embodiment, the nozzle rows 55 include a first nozzle row 55A on one side (Y2 side) of the main scanning direction (Y direction) and a second nozzle row 55B on the other side (Y1 side) of the main scanning direction.

[0030] When discharging paint, the drive timing of each nozzle 54 is controlled so that droplets discharged from nozzles 54 in the second nozzle row 55B land between droplets discharged from adjacent nozzles 54 in the first nozzle row 55A, thereby improving the dot density during coating.

[0031] As shown in Fig. 2, a single paint head 53 is present on the nozzle forming surface 52. However, the nozzle forming surface 52 may have a head group made up of a plurality of paint heads 53. In this case, as an example, a configuration in which the plurality of paint heads 53 are aligned and arranged in a staggered pattern as shown in Fig. 3 can be given, but the arrangement of the paint heads 53 in the head group does not have to be staggered.

[0032] The paint is supplied to the nozzle pressurizing chamber 59 shown in Fig. 4 via a paint supply passage 72 (see Fig. 6), a nozzle supply flow passage 59a in the painting head 53, and other supply flow passages, and the nozzle 54 is formed in a predetermined portion (for example, the bottom surface) of this nozzle pressurizing chamber 59. Paint that is not discharged from the nozzle 54 is discharged via a discharge flow passage (not shown) in the painting head 53 that is connected to the nozzle pressurizing chamber 59. The discharge flow passage in the painting head 53 is connected to a return flow passage 73 of the paint supply mechanism 70, which will be described later.

[0033] With this configuration, paint supplied from a paint supply passage 72 of a paint supply mechanism 70 (described later) passes through a supply passage including a nozzle supply passage 59a in the painting head 53 and the nozzle pressurizing chamber 59, and is then discharged from the nozzle 54. Paint that has not been discharged from the nozzle 54 passes from the nozzle pressurizing chamber 59 through a discharge passage in the painting head 53, and is returned to a return passage 73 of the paint supply mechanism 70 (described later).

[0034] 4, a piezoelectric substrate 62 is disposed on the top surface of the nozzle pressurizing chamber 59 (the surface opposite 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 individual electrode 65. The piezoelectric ceramic layers 63a and 63b are members that can expand and contract when a voltage is applied from the outside. For such piezoelectric ceramic layers 63a and 63b, ceramic materials having ferroelectricity, such as lead zirconate titanate (PZT)-based, NaNbO3-based, BaTiO3-based, (BiNa)NbO3-based, and BiNaNb5O15-based materials, can be used.

[0035] As shown in FIG. 4, the common electrode 64 is disposed between the piezoelectric ceramic layer 63a and the piezoelectric ceramic layer 63b. A surface electrode (not shown) for the common electrode is formed on the upper surface of the piezoelectric substrate 62. The common electrode 64 and the surface electrode for the common electrode are electrically connected through a through conductor (not shown) present in the piezoelectric ceramic layer 63a. The individual electrodes 65 are disposed in the portions facing the nozzle pressurizing chamber 59. The portion of the piezoelectric ceramic layer 63a sandwiched between the common electrode 64 and the individual electrodes 65 is polarized in the thickness direction. Therefore, when a voltage is applied to the individual electrodes 65, the piezoelectric ceramic layer 63a is distorted by the piezoelectric effect. Therefore, when a predetermined drive signal is applied to the individual electrodes 65, the piezoelectric ceramic layer 63b is relatively displaced so as to reduce the volume of the nozzle pressurizing chamber 59, thereby discharging the paint.

[0036] 4, the common electrode 64 is disposed on the ceiling surface of the nozzle pressurizing chamber 59, but the common electrode 64 is not limited to the configuration in which it is disposed on the ceiling surface of the nozzle pressurizing chamber 59 as shown in Fig. 4. For example, the common electrode 64 may be disposed on the side surface of the nozzle pressurizing chamber 59 (a surface perpendicular or nearly perpendicular to the above-mentioned ceiling surface), or any other configuration may be adopted as long as the paint can be discharged satisfactorily from the nozzle 54.

[0037] (1-4. Other configurations of the painting head unit) Next, another configuration of the paint head unit 50 will be described. FIG. 5 is a plan view showing the configuration of the nozzle forming surface 52 of another paint head unit 50. As shown in FIG. 5, a nozzle row 55 may be configured by arranging a plurality of nozzles 54 along the short side direction (width direction; Y direction) of the paint head 53. In the configuration shown in FIG. 5, a plurality of nozzles 54 are arranged in the short side direction (width direction; main scanning direction) of the paint head 53 to form the nozzle row 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 paint head 53 may also be used. In other words, the nozzle row 55 may be configured by one nozzle 54.

[0038] Furthermore, when painting a vehicle using a paint head 53 as shown in Fig. 5, painting may be performed with the longitudinal direction of the paint head 53 slightly tilted with respect to the main scanning direction of the paint head 53. For example, in the configuration of the paint head 53 shown in Fig. 2, if the nozzle row 55 is tilted at an angle α with respect to the main scanning direction, the longitudinal direction of the paint head 53 may be tilted at the angle α with respect to the main scanning direction of the paint head 53. When tilted in this manner, painting equivalent to that of the paint head 53 shown in Fig. 2 can be achieved simply by adjusting the timing of paint ejection from each nozzle 54.

[0039] (1-5. Paint supply mechanism) Next, the paint supply mechanism 70 will be described. Fig. 6 is a diagram showing a schematic configuration of the paint supply mechanism 70, etc. The paint supply mechanism 70 mainly includes a paint circulation path 71, an external supply path 75, an air bubble removing 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.

[0040] 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 paint that has been supplied from an external supply path 75 or returned from the return path 73 toward the paint head 53, and is connected to the supply path within the paint head 53 described above.

[0041] The return flow path 73 is connected to the discharge flow path in the coating head 53 described above, and is a flow path for returning paint that has not been discharged from the coating head 53 to the air bubble removing member 76 .

[0042] The bypass flow path 74 is a flow path that connects the paint supply path 72 and the return flow path 73. In other words, the bypass flow path 74 is provided in parallel with the paint head 53, and when paint is not being ejected from the paint head 53, the operation of a three-way valve 77, which will be described later, is switched so that paint flows into this bypass flow path 74.

[0043] The external supply passage 75 is a pipe for supplying paint supplied from a paint storage portion such as a circulation tank to the inside of the tank body of the air bubble removing member 76 .

[0044] The air bubble removal member 76 is a member for removing air bubbles contained in paint. The air bubble removal member 76 is provided at a stable position outside the robot arm R1 where the posture does not change. The air bubble removal member 76 is connected to the paint supply path 72 so as to be able to supply paint, and is also connected to the return flow path 73 so as to be supplied with paint from the return flow path 73. The air bubble removal member 76 has a tank body that can be sealed from the outside, and the tank body is provided with an outlet for discharging gas caused by air bubbles that have accumulated inside.

[0045] Furthermore, the paint supply passage 72 is connected to a three-way valve 77 downstream of a first paint regulator 92, which will be described later. This three-way valve 77 is connected to a midway portion of the paint supply passage 72, and is also connected to a bypass passage 74. Therefore, during painting, the upstream and downstream sides of the paint supply passage 72 relative to the three-way valve 77 are open, and paint is supplied to the painting head 53. On the other hand, when painting is not being performed, paint flows from the paint supply passage 72 to the bypass passage 74, but is switched so that paint is not supplied to the downstream side of the paint supply passage 72 (the painting head 53 side).

[0046] Further, an on-off valve 78 is provided in the middle of the bypass flow passage 74. By operating this on-off valve 78 to open, the paint can flow through the bypass flow passage 74.

[0047] Furthermore, a three-way valve 79 is connected downstream of the on-off valve 78 in the bypass flow passage 74, and this three-way valve 79 is further connected to the upstream side (i.e., the paint head 53 side of the return flow passage 73) and the downstream side (i.e., the suction pump 91 side of the return flow passage 73 described later). Therefore, when painting is performed, the upstream side and downstream side of the return flow passage 73 from the three-way valve 79 are opened, and paint that has not been discharged from the paint head 53 flows to the downstream side of the return flow passage 73. On the other hand, when painting is not performed, the three-way valve 79 is switched so that the paint flowing through the bypass flow passage 74 flows to the downstream side of the return flow passage 73 (the suction pump 91 side).

[0048] In addition, a switching valve 80 is disposed downstream of a suction pump 91, which will be described later, in the return flow passage 73. This switching valve 80 is also a three-way valve, and is connected to a discharge passage 81 in addition to the upstream and downstream sides of the return flow passage 73. In a normal state, this switching valve 80 is in a state in which paint flows between the upstream and downstream sides of the return flow passage 73. However, for example, when a cleaning liquid flows from the paint supply passage 72 to the return flow passage 73 via the coating head 53 or the bypass passage 74, the operation of the switching valve 80 is switched, and the above-mentioned cleaning liquid (waste liquid) is discharged via the discharge passage 81.

[0049] The return flow path 73 is connected to the above-mentioned air bubble removing member 76 downstream of the switching valve 80 .

[0050] A supply pump 90 is connected to the middle of the paint supply passage 72. The supply pump 90 corresponds to the paint transfer means and the paint supply means. The supply pump 90 is a means for applying a positive pressure to the paint flowing through the paint supply passage 72 toward the downstream side of the supply pump 90. It is preferable to use a gear pump as the supply pump 90, which can control the amount of paint supplied by controlling the rotation speed. However, a pump other than a gear pump may be used as the supply pump 90. The operation of the supply pump 90 is controlled by a control unit 100, which will be described later. Thereby, the operation of the supply pump 90 can be controlled to a predetermined pressure setting value.

[0051] A suction pump 91 is connected to the middle of the return flow passage 73. The suction pump 91 corresponds to the paint transfer means and the paint recovery means. The suction pump 91 is a means for applying negative pressure to the paint flowing through the return flow passage 73 upstream of the supply pump 90. As the suction pump 91, it is preferable to use a gear pump that can control the amount of paint supplied by controlling the rotation speed, similar to the supply pump 90. However, the suction pump 91 may be a pump other than a gear pump. The operation of the suction pump 91 is also controlled by the control unit 100 described later. Thereby, the operation of the suction pump 91 can be controlled so that the downstream side is at a predetermined pressure setting value.

[0052] A first paint regulator 92 is disposed in the paint supply passage 72 downstream of the supply pump 90. The first paint regulator 92 reduces pulsation in the supply pump 90 and supplies paint at a constant pressure. The first paint regulator 92 corresponds to an adjustment valve and a first adjustment valve. The first paint regulator 92 is capable of adjusting its opening in response to a control air pressure or an electric signal under the control of a control unit 100, which will be described later. This makes it possible to control the pressure downstream of the first paint regulator 92 to a predetermined pressure setting value in response to the pressure upstream of the first paint regulator 92.

[0053] Further, a second paint regulator 93 is disposed in the return flow passage 73 upstream of the suction pump 91. The second paint regulator 93 reduces pulsation in the suction pump 91 and sucks in paint at a constant pressure (negative pressure). This second paint regulator 93 is also capable of adjusting its opening in response to the control air pressure and electrical signals under the control of the control unit 100, which will be described later. As a result, the pressure on the upstream side of the second paint regulator 93 can be controlled to a predetermined pressure set value in response to the pressure on the downstream side of the second paint regulator 93.

[0054] Further, in the paint supply passage 72, a degassing module 94 is disposed downstream of the supply pump 90 and upstream of the first paint regulator 92. The degassing module 94 is disposed downstream of the paint supply passage 72 from a removal filter 95 (described later), and is a member for removing (degassing) dissolved gasses dissolved in the paint.

[0055] Further, in the paint supply passage 72, a removal filter 95 is disposed upstream of the deaeration module 94 and downstream of the supply pump 90. The removal filter 95 removes foreign matter contained in the paint flowing through the paint supply passage 72. The removal filter 95 ensures that the paint head 53 can continue to operate normally by reliably removing coarse foreign matter and pigment aggregates from paint that contains, for example, pigment.

[0056] Next, the pressure sensors S1 to S8 and the flow meters FM1, FM2 will be described. In the paint supply path 72, a pressure sensor S1 is disposed upstream of the supply pump 90. In addition, in the paint supply path 72, a pressure sensor S2 is disposed 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 transmits the measurement result to the control unit 100. In addition, the pressure sensor S2 measures the pressure of the paint discharged from the supply pump 90 and transmits the measurement result to the control unit 100.

[0057] In this way, by measuring the paint pressure upstream and downstream of the supply pump 90 using the pressure sensors S1 and S2, it is possible to accurately measure the estimated pressure of the supply pump 90. The estimated pressure of the supply pump 90 may be the average value of the pressure value of the pressure sensor S1 and the pressure sensor S2, or it may be the pressure value of either one of them. The estimated pressure is used to calculate the head pressure and head pressure difference, which will be described later.

[0058] Further, a vacuum pump 97 is connected to the above-mentioned degassing module 94 via a suction pipe 96. As described above, the vacuum pump 97 is a device for reducing the pressure inside the housing of the degassing module 94 (inside the hollow fiber membrane). This reduction in pressure removes (degass) dissolved gases dissolved in the paint supplied inside the housing.

[0059] Moreover, the pressure sensor S3 measures the pressure in the suction line 96 between the vacuum pump 97 and the degassing module 94.

[0060] A first flow meter FM1 is disposed in the paint supply passage 72 downstream of the deaeration module 94 and upstream of the first paint regulator 92. The first flow meter FM1 measures the flow rate of paint fed to the first paint regulator 92 and transmits the measurement result to the control unit 100. This first flow meter FM1 is a non-contact type flow meter that has no moving parts, such as an ultrasonic, optical, electromagnetic, or thermal type, and therefore the first flow meter FM1 is disposed outside the paint supply passage 72. The first flow meter FM1 may be a flow meter that has moving parts.

[0061] Furthermore, a pressure sensor S4 is disposed in the paint supply passage 72 downstream of the first flow meter FM1 and upstream of the first paint regulator 92. Furthermore, a pressure sensor S5 is disposed in the paint supply passage 72 downstream of the first paint regulator 92 and upstream of the three-way valve 77. The pressure sensor S4 measures the pressure of paint supplied to the first paint regulator 92 and transmits the measurement result to the control unit 100. Furthermore, the pressure sensor S5 measures the pressure of paint discharged from the first paint regulator 92 and transmits the measurement result to the control unit 100.

[0062] In this way, by using pressure sensors S4, S5 to measure the paint pressure upstream and downstream of the first paint regulator 92, it is possible to accurately measure the estimated pressure of the first paint regulator 92. The estimated pressure of the first paint regulator 92 may be the average value of the pressure value of pressure sensor S4 and the pressure value of pressure sensor S5, or it may be the pressure value of either one of them.

[0063] It is preferable that the paint supply mechanism 70 is provided with the pressure sensor S4, but a configuration in which the pressure sensor S4 is omitted may be adopted. The pressure sensor S4 may be provided on the paint head unit 50 side, or on the second rotating arm 25 side (robot arm R1 side). The pressure sensor S4 may be provided upstream of the first flow meter FM1.

[0064] Furthermore, a pressure sensor S6 is disposed in the return flow path 73 downstream of the three-way valve 79 and upstream of the second paint regulator 93. Furthermore, a pressure sensor S7 is disposed in the return flow path 73 further downstream of a flow meter FM2 (described below) which is downstream of the second paint regulator 93. The pressure sensor S6 measures the pressure of paint supplied to the second paint regulator 93 and transmits the measurement result to the control unit 100. Furthermore, the pressure sensor S7 measures the pressure of paint discharged from the second paint regulator 93 (i.e., the pressure of paint supplied to the suction pump 91) and transmits the measurement result to the control unit 100.

[0065] In this way, by using pressure sensors S6, S7 to measure the paint pressure upstream and downstream of the second paint regulator 93, it is possible to accurately measure the estimated pressure of the second paint regulator 93. The estimated pressure of the second paint regulator 93 may be the average value of the pressure value of pressure sensor S6 and the pressure value of pressure sensor S7, or it may be the pressure value of either one of them.

[0066] It should be noted that a pressure sensor may be disposed in the return flow passage 73 downstream of the second paint regulator 93 and upstream of the flow meter FM2.

[0067] A second flow meter FM2 is disposed in the return flow passage 73 downstream of the second paint regulator 93. The second flow meter FM2 measures the flow rate of paint fed to the suction pump 91 and transmits the measurement result to the control unit 100. Like the above-mentioned first flow meter FM1, this second flow meter FM2 is also a non-contact type flow meter that has no moving parts, such as an ultrasonic type, optical type, electromagnetic type, or thermal type, and therefore a detailed description thereof will be omitted. Note that the second flow meter FM2 may also be a flow meter that has moving parts.

[0068] In addition, 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.

[0069] In this way, by using pressure sensors S7 and S8 to measure the paint pressure upstream and downstream of the suction pump 91, it is possible to accurately measure the estimated pressure of the suction pump 91. The estimated pressure of the suction pump 91 may be the average value of the pressure value of the pressure sensor S7 and the pressure sensor S8, or it may be the pressure value of either one of them.

[0070] (1-8. Schematic configuration of the control unit)

[0071] Next, a schematic configuration of the control unit 100 for controlling the operation of the painting robot 10 will be described. Fig. 7 is a diagram showing a schematic control configuration centered on the control unit 100 of the painting robot 10. As shown in Fig. 7, 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 an inclination sensor 310. The painting robot 10 is connected to an image processing device 200 to form a painting robot system (reference numerals omitted).

[0072] The main control unit 110, arm control unit 120, head control unit 130, paint supply control unit 140, and image processing unit 210 described below are composed of a CPU (Central Processing Unit), storage units (ROM (Read Only Memory), RAM (Random Access Memory), non-volatile memory, etc.), and other elements. The image processing unit 210 may use a GPU (Graphics Processing Unit) together with a CPU with excellent image processing performance, or instead of the CPU.

[0073] Of the above control configurations, the main control unit 110 is a part that transmits predetermined control signals to the arm control unit 120, head control unit 130 and paint supply control unit 140 described above so that each motor (first to sixth motors) of the robot arm R1, each operating unit of the paint supply mechanism 70, and the piezoelectric substrate 62 work together to paint the object to be painted.

[0074] The arm control unit 120 is a unit that controls the driving of each motor (first to sixth motors) of the robot arm R1 described above. The arm control unit 120 is equipped with an arm memory (not shown), and the arm memory stores data on the trajectory of the paint head 53 (trajectory data) and posture data on the posture of the paint head 53, such as the inclination, that are created by robot teaching taking into account the paint width that can be painted by the paint head 53.

[0075] The arm control unit 120 controls the driving of each motor (first to sixth motors) of the robot arm R1 based on the trajectory data and posture data stored in the arm memory and image processing by the image processing unit 210 described later. This control allows the painting head 53 to pass a desired position for painting at a desired speed and to stop at a predetermined position. The arm memory may be provided in the painting robot 10, but an arm memory (for example, memory 220 shown in FIG. 7) may be provided outside the painting robot 10, and information may be transmitted to and received from the arm memory via wired or wireless communication means.

[0076] The head control unit 130 is a part that controls the operation of the piezoelectric substrate 62 in the paint head unit 50 based on image processing by the image processing device 200. When the head control unit 130 reaches a predetermined position in the trajectory data using a means for detecting the position, such as a position sensor 300 and an inclination sensor 310 described later, the head control unit 130 controls the discharge of paint based on the divided paint data corresponding to that position. In this case, the drive frequency of the piezoelectric substrate 62 is controlled to control the number of dots (number of droplets) discharged from the nozzle 54, and the deformation amount of the piezoelectric substrate 62 is controlled based on the drive frequency and / or voltage applied to the piezoelectric substrate 62 to control the size of the droplets discharged from the nozzle 54 so that the film thickness on the vehicle is uniform.

[0077] When controlling the droplet size by controlling the deformation amount of the piezoelectric substrate 62 based on the drive frequency applied to the piezoelectric substrate 62, the droplet size becomes largest when the piezoelectric substrate 62 is driven at a drive frequency that matches the natural frequency of the piezoelectric substrate 62. Therefore, the droplet size can be controlled to become smaller as the applied drive frequency deviates from the natural frequency. When controlling the droplet size by controlling the deformation amount of the piezoelectric substrate 62 based on the voltage applied to the piezoelectric substrate 62, the droplet size can be controlled to become larger as the voltage applied to the piezoelectric substrate 62 becomes higher.

[0078] Further, the paint supply control unit 140 is a part that controls the supply of paint to the painting head 53, and specifically controls the operation of each operating part in the paint supply mechanism 70, such as the supply pump 90, suction pump 91, first paint regulator 92, second paint regulator 93, vacuum pump 97, three-way valves 77, 79, on-off valve 78, and changeover valve 80. At this time, it is preferable that the paint supply control unit 140 controls the operation of the operating parts such as the pumps and valves so that paint is supplied to the painting head 53 at a constant pressure. However, the paint supply control unit 140 may also be capable of controlling the operation of the operating parts such as the pumps and valves so that paint is supplied to the painting head 53 at a constant flow rate.

[0079] Here, the paint supply control unit 140 is capable of accessing the control memory 150, and by such access, it is possible to read out data related to control, such as pressure setting values, stored in the control memory 150.

[0080] Moreover, the position sensor 300 is a sensor that detects the current position of the paint head 53. A rotary encoder, a resolver, a laser sensor, or other various sensors can be used as the position sensor 300. Moreover, the tilt sensor 310 is a sensor that detects the tilt angle of the paint head 53. A gyro sensor, an acceleration sensor, a tilt sensor, or other various sensors can be used as the tilt sensor 310.

[0081] (2. Droplet ejection control) The following describes the control performed when droplets are ejected from the nozzle 54 of the painting head 53 to form a painting area CR on an object to be painted, as shown in Fig. 8. In this embodiment, the image processing device 200 creates image data corresponding to the painting area CR as shown in Fig. 8, but the width of the painting area CR is usually sufficiently larger than the width of the painting head 53.

[0082] In such cases where the width of the painting area CR is sufficiently larger than the width of the painting head 53, the image processing device 200 creates divided painting data D1 by dividing the image data into strips corresponding to the paintable width (painting pass) of the painting head 53. Fig. 9 is a diagram showing an example of the divided painting data D1. By discharging paint based on such divided painting data D1, painting becomes possible every time the painting head unit 50 scans (every painting pass).

[0083] Since the divided painting data D1 is in the form of strips as described above, the areas where painting starts and ends are usually located on the edge of the painting area, and both ends of the divided painting data D1 in the arrangement direction are also located on the edge of the painting area.

[0084] In the following, in the divided painting data D1, the data area that is not located on the edge side of the painting area but is inside the edge side (data area for forming a paint film with a normal thickness) is referred to as the normal painting data area DR1. In addition, in the divided painting data D1, the data area that corresponds to the part located on the edge side of the painting area is referred to as the edge painting data area DR2.

[0085] After creating such divided painting data D1, the main control unit 110 transmits control signals for 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. The arm control unit 120 then drives at least one of the motors built into the robot arm R1 at a predetermined driving speed so that painting can be performed on the object to be painted. In addition, the paint supply control unit 140 starts discharging paint from one of the nozzles 54 of the paint head unit 50 when the paint head unit 50 reaches a predetermined spatial position relative to the object to be painted using the position sensor 300 and the tilt sensor 310.

[0086] At this time, the head control unit 130 controls the driving of the piezoelectric substrate 62 of each nozzle 54 so that paint is sequentially discharged from the nozzle 54 that has reached the edge of the object to be painted. As a result, a painted area CR as shown in FIG. 8 is formed on the object to be painted.

[0087] Here, in the above-mentioned coating area CR, a normal coating area CR1 formed by discharging paint corresponding to the normal coating data area DR1 and an end coating area CR2 formed by discharging paint corresponding to the end coating data area DR2 are formed for each coating pass PS. Details of this (details of control of droplet discharge) will be described below.

[0088] (2-1. Details of droplet ejection control) When droplets are ejected, in the normal painting data region DR1, whether or not to eject paint droplets from the nozzle 54 and the size of the paint droplets when ejecting paint are determined in accordance with a specified film thickness.

[0089] For example, it is assumed that the size of droplets can be adjusted to eight levels by adjusting the drive frequency and voltage of the piezoelectric substrate 62. In this case, in the normal painting area CR1 based on the normal painting data area DR1, droplets of relatively large size are ejected to ensure a sufficient thickness of the coating film. Here, the smallest droplet is droplet 1, the next smallest droplet is droplet 2, and thereafter, the droplet size increases as the numbers increase, with the largest droplet being droplet 8. In this case, in FIG. 9, for example, in painting based on the normal painting data area DR1, the entire area is painted with droplets 6 to 8.

[0090] In this case, when the paint head 53 starts to be driven from a stopped state, a relatively large pressure fluctuation occurs particularly inside the nozzle 54 to which the piezoelectric substrate 62 corresponds. Similarly, when the paint head 53 stops being driven from a driven state, a relatively large pressure fluctuation occurs particularly inside the nozzle 54 to which the piezoelectric substrate 62 corresponds.

[0091] When such pressure fluctuation occurs, paint may overflow from the meniscus formed near the opening of the nozzle 54. In the following, the area (droplets) formed around the nozzle 54 of the painting head 53 due to paint overflow is referred to as leaked paint P1. FIG. 10 is a cross-sectional view showing a state in which the leaked paint P1 has adhered to the periphery of the nozzle 54 due to paint overflow. As shown in FIG. 10, 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 caught in) the discharged droplets P2 newly discharged from the nozzle 54.

[0092] As a result, the discharged droplets P2 adhere to the object to be painted in a state larger than the intended droplet size, and therefore, particularly in the painting area corresponding to the end painting data area DR2, droplets larger than the expected droplet size land, resulting in a noticeable step.

[0093] Fig. 11 is a diagram showing a state where the vicinity of the edge coating area CR2 of the coating surface (coating area CR) is coated by the current droplet discharging method when discharging the discharged droplets P2. As shown in Fig. 11, in the current droplet discharging method, leaked paint P1 is formed near the nozzle 54 due to the influence of pressure fluctuation, and the discharged droplets P2 are discharged with the leaked paint P1 attached (entangled), forming a stepped outline CR3 and not a sharp outline. This leads to a deterioration in the parting quality of the edge coating area CR2 of the coating area CR.

[0094] Furthermore, if droplets cannot be discharged from the nozzle 54 due to the influence of the leaked paint P1, even if the nozzle 54 reaches the discharge start position where droplets should be discharged, the droplets cannot be discharged. In this case, if pressure can be applied to the paint that can break the surface tension of the leaked paint P1 or the film formed by solidification due to drying, it is possible to discharge droplets from the nozzle 54. However, in this case, the leaked paint P1 and the broken film hinder the discharge of droplets. Therefore, in this case, droplets smaller than usual are discharged, and there is a risk that the specified film thickness will not be reached, resulting in poor coating.

[0095] In addition, overflowing paint may cause the droplets to be ejected in an unintended direction, resulting in abnormal ejection. Such abnormal ejection of droplets may also result in a reduction in quality when forming the edge (contour) of the coating film.

[0096] In contrast, in this embodiment, when droplets are discharged based on the end painting data region DR2, the end painting data region DR2 is formed so that droplets of a smaller size (e.g., droplet 1 or droplet 2) are discharged compared to when droplets are discharged based on the normal painting data region DR1. Fig. 12 is a diagram showing the size of droplets to be discharged for each pixel near the end painting data region DR2. As shown in Fig. 12, the end painting data region DR2 is formed so that droplets of a smaller size, such as droplets 1 to 2, are discharged to pixels that may become the contour CR3 of the painting region CR after the droplets land.

[0097] In addition, the end painting data area DR2 is a data area including the extreme pixels corresponding to the painted contour CR3, and only the extreme pixels may correspond to the end painting data area DR2, or the pixels from the extreme pixel to several pixels inside the data may correspond to the end painting data area DR2.

[0098] In addition, in the end painting data region DR2, the end painting data region DR2 may be formed so that, in addition to large-sized droplets such as droplets 6 to 8, small-sized droplets such as droplets 1 to 2 are ejected to the areas adjacent to the large-sized droplets at pixels that may become the contour CR3 of the painted area CR after the droplets land.

[0099] Based on the divided painting data D1 having the end painting data region DR2 formed as described above, painting is performed in each painting pass. Then, in each painting pass, at the start and end of painting, the deformation amount (drive amount) of the piezoelectric substrate 62 is reduced in order to eject droplets of a smaller size compared to when painting the normal painting data region DR1. In this state, the end painting region CR2 of the painting region CR is formed (corresponding to the end painting step).

[0100] Therefore, particularly when the paint head 53 starts to be driven from a stopped state, it is possible to prevent pressure fluctuations from increasing inside the nozzle 54 associated with the piezoelectric substrate 62. Similarly, even when the paint head 53 is stopped from being driven from a driven state, it is possible to prevent pressure fluctuations from increasing inside the nozzle 54 associated with the piezoelectric substrate 62.

[0101] Therefore, it is possible to prevent the formation of leaked paint P1 near the opening of the nozzle 54, as shown in Figure 10, thereby preventing the leaked paint P1 from adhering to (being caught up in) the newly ejected droplets P2 ejected from the nozzle 54.

[0102] After the end painting step is performed, the piezoelectric substrate 62 is operated in a state in which the deformation of the piezoelectric substrate 62 is greater than in the end painting step, and painting of the normal painting area CR1 is performed (corresponding to the inside painting step).

[0103] Here, Fig. 13 shows the state where the vicinity of the end coating area CR2 of the coating area CR is coated using the droplet discharge method of this embodiment. As shown in Fig. 13, the droplet discharge method of this embodiment forms a sharper outline with less steps in the outline CR3 of the coating area CR compared to the current droplet discharge method shown in Fig. 11. This makes it possible to improve the parting quality of the end coating area CR2 of the coating area CR.

[0104] In order to further suppress the effects of pressure fluctuations, the head control unit 130 may control the driving of the piezoelectric substrate 62 so that the amount of deformation of the piezoelectric substrate 62 during painting of the end coating area CR2 increases with distance from the contour CR3 of the end coating area CR2. Figure 14 shows such a state in which the droplet size is set for each pixel, different from that shown in Figure 12. Figure 14 shows a state in which the droplet size gradually increases from droplet 1 with distance from the contour CR3.

[0105] (3. About the effects) As described above, the painting robot 10 that paints the painting area CR of a vehicle comprises a painting head unit 50 that has a plurality of nozzles 54 that eject droplets, a painting head 53 that has a piezoelectric substrate 62 that is driven to push the droplets out of the nozzles 54, a robot arm R1 that has the painting head unit 50 attached to its tip and moves the painting head unit 50 to a desired position, and a control unit 100 that has a head control unit 130 that controls the operation of the piezoelectric substrate 62 of the painting head 53, and an arm control unit 120 that controls the operation of the robot arm R1.

[0106] The head control unit 130 controls the operation of the piezoelectric substrate 62 so that the amount of 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 amount of deformation of the piezoelectric substrate 62 when painting the normal painting area CR1 which is more inward than the end side of the painting area CR.

[0107] In this way, in painting the end painting area CR2, which corresponds to at least one of the timings at which the pressure fluctuation is large, namely, the start of painting and the end of painting, the head control unit 130 controls the operation of the piezoelectric substrate 62 so that the deformation amount of the piezoelectric substrate 62 is smaller than the deformation amount of the piezoelectric substrate 62 when painting the normal painting area CR1 inside the painting area CR. This makes it possible to reduce the influence of pressure fluctuations caused by the deformation of the piezoelectric substrate 62 in painting the end painting area CR2. This makes it possible to prevent the leaked paint P1 from being formed near the opening of the nozzle 54. This makes it possible to prevent the leaked paint P1 from adhering to (being caught in) the discharged droplets P2 newly discharged from the nozzle 54.

[0108] Also, by suppressing the formation of leaking paint P1 near the opening of the nozzle 54, it is possible to prevent the leaking paint P1 or a broken film from hindering the discharge of droplets. This makes it possible to prevent the nozzle 54 from being unable to discharge droplets even when it reaches the discharge start position where droplets should be discharged. It is also possible to prevent a coating defect that occurs when droplets smaller than normal are discharged and the specified film thickness is not reached.

[0109] It is also possible to prevent abnormal ejection, such as when the ejection direction of droplets is changed to an unintended direction due to overflowing paint.

[0110] Furthermore, when painting the end coating area CR2, it is possible to make the size of the droplets discharged from the nozzle 54 smaller than the size of the droplets when painting the normal coating area CR1. This makes it possible to reduce the step between the landing droplets when forming the contour CR3 of the coating area CR, thereby making it possible to form a sharper contour with higher coating quality.

[0111] In addition, in this embodiment, the driving frequency of the piezoelectric substrate 62 in the normal painting area CR1 can be set to a frequency at which the resonance of the piezoelectric substrate 62 is greater than the driving frequency of the piezoelectric substrate 62 when painting the end painting area CR2.

[0112] By controlling the piezoelectric substrate 62 in this way, the driving frequency of the piezoelectric substrate 62 during painting of the end painting area CR2, which corresponds to at least one of the start and end of painting, is shifted from the frequency at resonance (natural frequency). Therefore, the piezoelectric substrate 62 is more likely to be driven in the direction of canceling the vibration. Therefore, it is possible to reduce the size of the droplets discharged from the nozzle 54 during painting of the end painting area CR2. This makes it possible to prevent the paint from overflowing from the nozzle 54 due to the large pressure fluctuation of the paint during painting of the end painting area CR2. Therefore, it is possible to prevent the leaked paint P1 from adhering to (being caught in) the discharged droplets P2 newly discharged from the nozzle 54.

[0113] Furthermore, when forming the contour CR3 of the coating area CR, it is possible to reduce the steps between the impacted droplets, thereby making it possible to form a sharper contour with higher coating quality.

[0114] In addition, in this embodiment, the head control unit 130 may be configured to control the driving of the piezoelectric substrate 62 so that the amount of deformation of the piezoelectric substrate 62 when painting the end painting area CR2 increases as the piezoelectric substrate 62 moves away from the contour of the end painting area CR2.

[0115] When controlled in this manner, the size of the droplets discharged from the nozzle 54 increases from the end of the coating region CR toward the center. In other words, the size of the landing droplets gradually decreases toward the end of the coating film being formed, thereby forming an inclined portion in the coating film. Therefore, by gradually decreasing the size of the landing droplets toward the end, it is possible to suppress the paint from flowing out toward the end, and it is possible to further improve the coating quality.

[0116] (4. Modifications) Although one embodiment of the present invention has been described above, the present invention can be modified in various ways in addition to the above embodiment. Modifications will be described below.

[0117] In the above-described embodiment, instead of the painting pass PS as shown in Fig. 8, the arm control unit 120 may rotate the end painting area located on the periphery of the painting area CR when painting the painting area CR. Furthermore, after painting of the end painting area CR2 is completed, the operation of the robot arm R1 may be controlled so as to paint the normal painting area CR1 surrounded by the end painting area CR2, and the head control unit 130 may control the operation of the piezoelectric substrate 62 so 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.

[0118] By controlling the operation of the robot arm R1 in this manner, when painting the end painting area CR2 from the start of painting, painting is performed with the amount of deformation of the piezoelectric substrate 62 smaller than when painting the normal painting area CR1 on the inner side. Therefore, when painting the contour CR3 of the painting area CR, it is possible to reduce the size of the droplets discharged from the nozzle 54. This makes it possible to prevent the paint from overflowing from the nozzle 54 due to large pressure fluctuations in the paint when painting the end painting area CR2 from the start of painting.

[0119] Furthermore, when forming the contour CR3 of the coating area CR, it is possible to reduce the steps between the impacted droplets, thereby making it possible to form a sharper contour with higher coating quality.

[0120] In the above embodiment, the divided painting data D1 is formed for each painting pass PS, and the end painting data area DR2 exists for each divided painting data D1. However, it is considered that the pressure fluctuation becomes large at the start of painting in the first painting pass PS and at the end of painting in the last painting pass PS among the series of (plural) painting passes PS for forming the painting area CR. Therefore, it is possible to perform control so as to suppress the deformation amount of the piezoelectric substrate 62 in the end painting area CR2 at the start of painting in the first painting pass PS and at the end of painting in the last painting pass PS among the series of (plural) painting passes PS for forming the painting area CR.

[0121] In addition, in adjacent painting passes PS, an end painting area CR2 may be set in the area where painting is performed over, or the end painting area CR2 may not be set.

[0122] In the above embodiment, the nozzle forming surface 52 where the nozzle 54 is exposed may be flat, but may also be configured to have a convex portion formed around the opening of the nozzle 54. In this case, the periphery of the opening of the nozzle 54 may be protruded over the entire circumference, or a part (a single portion or multiple portions) of the entire circumference may be protruded. In such a configuration, for example, the path length of the nozzle 54 may be extended, or the bank-shaped top may be slightly separated from the opening of the nozzle 54, thereby preventing the leaked paint P1 from being formed near the opening of the nozzle 54 during pressure fluctuations.

[0123] Also, a configuration may be adopted in which a concave portion is formed around the opening of the nozzle 54 by recessing it from the plane of the nozzle forming surface 52. In such a configuration, the leaking paint P1 is formed on the nozzle forming surface 52 below the recessed portion, so that the leaking paint P1 can be prevented from being formed in the vicinity of the opening of the nozzle 54 during pressure fluctuations.

[0124] In addition, in the above-described embodiment, in order to reduce the effects of vibration of the meniscus of the paint present in the nozzle 54, the head control unit 130 may control the piezoelectric substrate 62 to be given a Pull-Push-Pull type drive waveform that draws paint into the nozzle 54, pushes it out, and then draws the paint in again. [Explanation of symbols]

[0125] 10...painting robot, 11...painting robot system, 20...robot body, 21...base, 22a...first rotating shaft, 22b...second rotating shaft, 22c...third rotating shaft, 22d...fourth rotating shaft, 22e...fifth rotating shaft, 22f...sixth rotating shaft, 24...first rotating arm, 25...second rotating arm, 26...rotating arm, 27...wrist portion, 50...painting head unit, 52...nozzle forming surface, 53...painting head, 54...nozzle, 55...nozzle row, 55A...first 1 nozzle row, 55B... second nozzle row, 59... nozzle pressurizing chamber, 59a... nozzle supply flow path, 62... piezoelectric substrate, 63a... piezoelectric ceramic layer, 63b... piezoelectric ceramic layer, 64... common electrode, 65... individual electrode, 70... paint supply mechanism, 71... paint circulation path, 72... paint supply path, 73... return path, 74... bypass path, 75... external supply path, 76... air bubble removal member, 77... three-way valve, 78... opening / closing valve, 79... three-way valve, 80... switching valve, 81... discharge path, 9 0...supply pump (corresponding to paint supply means), 91...suction pump (corresponding to paint recovery means), 92...first paint regulator (corresponding to first adjustment valve), 93...second paint regulator (corresponding to second adjustment valve), 94...deaeration module, 95...removal filter, 96...suction line, 97...vacuum pump, 100...control unit, 110...main control unit, 120...arm control unit, 130...head control unit, 140...paint supply control unit, 150...control memory, 200...image processing device, 210...image processing section, 220...memory, 300...position sensor, 310...tilt sensor, CR...painting area, CR1...normal painting area, CR2...edge painting area, CR3...contour, D1...divided painting data, DR1...normal painting data area, DR2...edge painting data area, FM1...first flow meter, FM2...second flow meter, P1...leaking paint, P2...discharged droplets, PS...painting path, R1...robot arm, S1 to S8...pressure sensors

Claims

1. A painting robot that paints a painting area of ​​a vehicle, a coating head unit including a coating head having a plurality of nozzles for ejecting droplets and a piezoelectric substrate for driving the coating head to push out the droplets from the nozzles; a robot arm having a tip end to which the painting head unit is attached and which moves the painting head unit to a desired position; A control unit including a head control unit that controls the operation of the piezoelectric substrate of the paint head, and an arm control unit that controls the operation of the robot arm, The head control unit controls the operation of the piezoelectric substrate so that a deformation amount of the piezoelectric substrate during painting of an end painting area on the end side of the painting area is smaller than a deformation amount of the piezoelectric substrate during painting of a normal painting area on the inner side of the end side of the painting area. A painting robot characterized by the above.

2. The painting robot according to claim 1, A driving frequency of the piezoelectric substrate during painting of the normal painting area is set to a frequency at which resonance of the piezoelectric substrate becomes greater compared to a driving frequency of the piezoelectric substrate during painting of the edge painting area. A painting robot characterized by the above.

3. The painting robot according to claim 1, the head control unit controls driving of the piezoelectric substrate so that a deformation amount of the piezoelectric substrate during painting of the end painting region increases with distance from the contour of the end painting region. A painting robot characterized by the above.

4. The painting robot according to claim 1, The arm control unit controls the operation of the robot arm so that, when painting the painting area, the end painting area located on the periphery of the painting area is rotated, and after painting of the end painting area is completed, the normal painting area surrounded by the end painting area is painted; the head control unit controls the operation of the piezoelectric substrate so that a deformation amount of the piezoelectric substrate is smaller when painting the end painting area than a deformation amount of the piezoelectric substrate when painting the normal painting area. A painting robot characterized by the above.

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

6. The painting robot according to any one of claims 1 to 5, The head control unit controls the piezoelectric substrate to apply a pull-push-pull type drive waveform that draws paint into the nozzle, then pushes it out, and draws the paint back in after the push-out. A painting robot characterized by the above.

7. A painting method for painting a painting area of ​​a vehicle using a painting robot, comprising: The painting robot includes: a coating head unit including a coating head having a plurality of nozzles for ejecting droplets and a piezoelectric substrate for driving the coating head to push out the droplets from the nozzles; a robot arm having a tip end to which the painting head unit is attached and which moves the painting head unit to a desired position; A control unit including a head control unit that controls the operation of the piezoelectric substrate of the paint head, and an arm control unit that controls the operation of the robot arm, an edge painting step of controlling the operation of the piezoelectric substrate by the head control unit so that the amount of deformation of the piezoelectric substrate during painting of an edge painting area on the edge side of the painting area is smaller than the amount of deformation of the piezoelectric substrate during painting of a normal painting area that is more inward than the edge side of the painting area; an inside painting step in which, after the edge painting step, the piezoelectric substrate is operated in a state in which the deformation amount of the piezoelectric substrate is larger than that of the edge painting step, thereby painting the normal painting area; A coating method comprising:

Images