Inkjet coating method and inkjet coating system

Abstract

[Problem] To improve the accuracy of coating an object using an articulated robot. [Solution] The present invention performs coating of an object using an articulated robot 30 having inkjet heads in a robotic coating process that performs coating of an object P by a horizontal gantry 22 that moves a gantry 20 having a plurality of inkjet heads 40 in the horizontal direction and is configured so that the inkjet heads face downward and a vertical gantry 21 that moves in the horizontal direction and is configured so that the inkjet heads face sideways.

Description

Inkjet coating method and inkjet coating system

[0001] The present invention relates to an inkjet coating method and an inkjet coating system.

[0002] The same automobile can be divided into many different types depending on the paint job it is painted with. Conventional vehicle painting technology describes a multi-axis robotic hand equipped with a paint application device that applies paint, a print head that ejects paint from multiple paint nozzles, and a position detection system that detects the spatial position of the print head, etc.

[0003] Japanese Patent Application Laid-Open No. 2017-35693

[0004] The present inventors have focused on the fact that painting accuracy is relatively low when using articulated robots, and have been actively studying ways to improve the accuracy of painting when using articulated robots.

[0005] An object of the present invention is to improve the accuracy of painting an object using an articulated robot.

[0006] One aspect of the present invention is an inkjet coating method for an object, which includes a gantry coating process and a robot coating process. In the gantry coating process, a gantry having multiple inkjet heads is driven horizontally, and coating of the object is performed by a horizontal gantry with the inkjet heads facing downward and a vertical gantry driven horizontally with the inkjet heads facing sideways. In the robot coating process, coating of the object is performed by multiple articulated robots each having multiple inkjet heads.

[0007] One aspect of the present invention is an inkjet coating system having a gantry coating stage and a robot coating stage. The gantry coating stage has a horizontal gantry that has multiple inkjet heads attached facing downward and that moves horizontally, and a vertical gantry that has inkjet heads attached facing sideways and that moves horizontally. The robot coating stage is equipped with multiple articulated robots each equipped with an inkjet head.

[0008] According to the inkjet coating method and inkjet coating system, the precision of vehicle painting can be improved by using an articulated robot.

[0009] 1. A schematic perspective view showing an inkjet coating system according to a first embodiment. A side view of FIG. 1. A block diagram showing the device configuration of the inkjet coating system. A diagram showing the arrangement of inkjet heads attached to a gantry. A flowchart showing an inkjet coating method according to a first embodiment. A schematic view showing the configuration of an inkjet coating system according to a first modified example of the first embodiment. A schematic view showing the inkjet coating method according to a second modified example of the first embodiment. A schematic view showing the relationship between a gantry and an object according to a third modified example of the first embodiment. A schematic view showing the configuration of an inkjet coating system according to a fourth modified example of the first embodiment. A schematic view showing the movement of a gantry according to a fifth modified example of the first embodiment. A perspective view of FIG. 10. A schematic view showing the movement of a gantry according to a sixth modified example of the first embodiment. A perspective view of FIG. 12.

[0010] First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicate explanations will be omitted. In the drawings, the size and proportions of each component are exaggerated to facilitate understanding of the embodiment, and may differ from the actual size and proportions.

[0011] 1 and 2 are a schematic perspective view and a side view showing an inkjet coating system according to a first embodiment. FIG. 3 is a block diagram showing the configuration of the inkjet coating system. The inkjet coating system according to this embodiment can be used to paint objects such as automobiles. As shown in FIG. 3, the inkjet coating system includes a conveyor 10, a gantry 20, an articulated robot 30, an inkjet head 40, and a control unit 50. The inkjet coating system will be described in detail below.

[0012] The conveyor 10 is formed endlessly and is configured to transport the object P to the stage S where the gantry coating process is performed and the stage S where the robot coating process is performed. In this embodiment, the conveyor 10 is configured to transport the object P in a horizontal direction.

[0013] The gantry 20 is configured to be equipped with an inkjet head 40 in addition to robotic application. In this embodiment, the gantry 20 includes two vertical gantries 21 and a horizontal gantry 22 connecting the two vertical gantries 21. An inkjet head 40 is provided on each of the two vertical gantries 21 and one horizontal gantry 22. The inkjet head 40 is attached to the horizontal gantry 22 facing downward. The inkjet head 40 is attached to the vertical gantry 21 facing sideways. The horizontal gantry 22 is configured to be movable up and down in the vertical direction relative to its vertical shape using a motor or other configuration. At least one of the gantry 20 and the object P is configured to be movable back and forth in the horizontal direction relative to the stage S. The horizontal gantry 22 of the gantry 20 is configured to be movable up and down relative to the vertical gantry 21 using a motor, gear pair, or other configuration.

[0014] The articulated robot 30 has multiple arms connected together, and is specifically configured as a six-axis robot. Each axis of the articulated robot can be driven by an AC servo motor or the like. The articulated robot 30 can be configured to have six degrees of freedom. The articulated robot 30 can be set to operate based on a coordinate system. An inkjet head 40 is attached to the tip of the articulated robot 30.

[0015] FIG. 4 shows the arrangement of inkjet heads 40 attached to the gantry 20. The inkjet head 40 is configured to eject ink onto the object P placed on the stage S. The inkjet head 40 has multiple nozzles that eject ink onto the object P. The inkjet heads 40 can be installed on the vertical gantry 21 and horizontal gantry 22 of the gantry 20 and on the tip of the articulated robot 30. The inkjet heads 40 can be arranged so that their positions in the width direction are offset as shown in FIG. 4 when multiple gantries 20 are arranged in the front-to-rear direction. The inkjet heads 40 may have areas at the end of their ink-ejecting tips where ink cannot be ejected. However, by offsetting the positions of the inkjet heads 40 in the width direction when the gantries 20 are arranged adjacently in the front-to-rear direction as described above, the object P can be painted without gaps. When multiple inkjet heads 40 are mounted on the gantry 20, multiple inkjet heads 40 can be arranged, which means that it is more suitable for painting wide areas than narrow areas.

[0016] The control unit 50 is configured to control the movements of the conveyor 10, the gantry 20, the articulated robot 30, and the inkjet head 40. The control unit 50 can be configured to include a calculation unit such as a CPU, a storage unit such as a RAM or ROM, and a communication unit for communicating with peripheral devices. The storage unit can store the three-dimensional shape and position of an object to be coated, such as a vehicle transported to the stage.

[0017] (Inkjet Coating Method) Next, the inkjet coating method according to this embodiment will be described. FIG. 5 is a flowchart showing the inkjet coating method. A vehicle, which is the object P, is carried by a conveyor 10, and stops at each stage S, where work is carried out at each stage S. Note that before the painting process, the vehicle body is transported without window glass, lights, etc. attached. The inkjet coating method has a first coating process in which coating is performed by a gantry 20, and a second coating process in which coating is performed by an articulated robot 30, which is provided downstream of the coating process by the gantry 20.

[0018] In this embodiment, ink is first ejected from the inkjet heads 40 installed on the vertical gantry 21 and horizontal gantry 22 of the gantry 20 and sprayed onto the target P. A plurality of gantries 20 are installed in the longitudinal direction of the vehicle, and an inkjet head 40 is installed on the vertical gantry 21 and horizontal gantry 22 of each gantry. This allows ink to be applied to many parts of the vehicle's exterior surface in the gantry application process. In addition, the horizontal gantry 22 is movable in the vertical direction, so the distance between it and the target P can be adjusted (S1).

[0019] After the gantry coating process, the vehicle, which is the object, is transported to the robot coating stage S. Here, ink is ejected from the inkjet head 40 mounted at the tip of the articulated robot 30 toward the outer surface of the object P that has been coated by the gantry 20 (S2). This allows for complete coating even in areas of a complex shape such as a car body that could not be completely coated in the gantry coating process. By performing the robot coating process after the gantry coating process in this way, it is possible to finish off any areas that have not been coated in the gantry coating process. This allows the robot coating process to coat areas that have not been coated in the gantry coating process. Furthermore, the coating process according to this embodiment can be performed in the same amount of time as conventional coating processes.

[0020] (Variation 1) A variation of the above embodiment will be described below. Note that a description of the same configuration as the above embodiment will be omitted. In the above embodiment, a coating step using a gantry is performed as the first coating step, and coating using the articulated robot 30 is performed as the second coating step. However, the following steps can be performed before the first coating step.

[0021] 6 is a diagram showing an inkjet coating method according to Modification 1. Before the first coating step, a 3D scan is performed by a measuring unit 60 to obtain the shape of the target object P, such as a vehicle, and the three-dimensional coordinates of a representative position of the shape, and this data can be used for trajectory control of at least one of the robot coating steps in the gantry coating step.

[0022] The measurement unit 60 is configured to capture the shape of an object P to be coated, such as a vehicle. The measurement unit 60 is configured to perform a 3D scan to acquire information about the shape of the object P. The measurement unit 60 can acquire information about the three-dimensional position, such as the shape of the object P when viewed from a measurement position and the distance in the depth direction of the shape.

[0023] The measurement unit 60 may include an irradiation unit that irradiates light, such as a laser or LED, to determine the position of the object P, and a receiving unit that includes a camera that acquires information about the position and shape of the object P and a camera that acquires information about the color of the object P and receives light reflected from the object P. The measurement unit 60 may also include a calculation unit that calculates the unevenness, position, shape, etc. of the object P from the received light, etc. Here, the configuration of the irradiation unit and light receiving unit required for 3D scanning can be installed on the horizontal gantry 22 and vertical gantry 21 of the gantry 20, and can transmit and receive light, etc., and process the acquired data. This allows correction for vehicle assembly errors and transportation errors.

[0024] Furthermore, although the 3D scan of the vehicle (object P) is described above as being performed before the first coating step, the 3D scan may also be performed after the first coating step and before the second coating step to obtain data on the measurement range. This configuration allows for the recognition of areas that were insufficiently coated in the first coating step, and the second coating step can be performed to reduce or eliminate uneven coating around the insufficiently coated areas during the second coating step. Furthermore, by detecting areas that have not been painted after the first coating step, it is possible to complete the painting without any omissions. The receiving unit was described above as a camera that acquires information on the position and shape of the object P and information on the color of the object P. Here, color information may not be acquired before the first coating step if information on the position and shape of the object P can be acquired, and color information may not be acquired before the second coating step if color information can be acquired.

[0025] (Variation 2) Fig. 7 is a side view showing an inkjet application method according to Variation 2. Ink may be applied to the vehicle back door B, which is the target object P, in a closed state as shown in Fig. 2 etc., but ink may also be applied to the back door B in a state where it is opened by flipping it up as shown in Fig. 7. This allows ink to be applied without changing the angle of the inkjet head 40 on the horizontal gantry 22 of the gantry 20.

[0026] (Variation 3) FIG. 8 is a diagram showing the positional relationship between the inkjet head 40 and the object P according to Variation 3. In the above description, the inkjet head 40 is fixedly installed on the horizontal gantry 22 and the vertical gantry 21 of the gantry 20 to apply ink to the object P (i.e., a vehicle). However, the inkjet head 40 may be configured to move up and down independently in the vertical direction on the horizontal gantry 22, etc. The inkjet head 40 can be raised and lowered by attaching a distance sensor nearby and communicating the distance between the distance sensor and the object P to the control unit 50 so that the distance between the inkjet head 40 and the object P is within a certain range. This allows the inkjet head 40 on the horizontal gantry 22 of the gantry 20 to move up and down in the vertical direction while maintaining a certain distance from the vehicle surface. This configuration allows the ink to be applied while following the complex shape of the vehicle surface, resulting in a good finish on the coated surface.

[0027] (Modification 4) Fig. 9 is a side view showing an inkjet coating method according to Modification 4. In the first embodiment, the robot coating stage is provided downstream of the gantry coating stage. However, as shown in Fig. 9, the gantry coating stage may be provided downstream of the robot coating stage, and ink may be applied to the object P that has been coated by the gantry coating stage. This configuration also makes it possible to coat areas that have not been coated in the robot coating process in the gantry coating process. This allows complex shapes to be coated entirely without any omissions.

[0028] (Variation 5) FIGS. 10 and 11 are side and perspective views showing an inkjet coating method according to Variation 5. The horizontal gantry 22 constituting the gantry may be configured to be rotatable around a rotation axis that is in the width direction near the installation surface of the object P. The gantry 20a including the horizontal gantry 22a and the vertical gantry 21a may be configured to rotate from the front to above the object P around a rotation axis that is in the width direction of the object P, as shown in FIG. 10 . This configuration makes it possible to easily paint areas that are difficult to reach with ink, such as bumpers. Note that while FIGS. 10 and 11 show the inkjet head 40 installed on the horizontal gantry 22a and the vertical gantry 21a in one stage, the horizontal gantry 22a and the vertical gantry 21a equipped with the inkjet head 40 may be provided in two separate stages.

[0029] (Variation 6) Figures 12 and 13 are plan and perspective views showing an inkjet coating method according to Variation 6. The vertical gantry 21b constituting the gantry may be configured to be rotatable around the vertical axis at approximately the center of the object P, such as a vehicle. This configuration makes it possible to easily paint areas of the vehicle that are difficult for ink to reach, from the side to the front and then to the other side. Furthermore, when acquiring the position coordinates of the object P by 3D scanning, position information may be acquired by scanning the object P hemispherically using a rotating gantry such as those shown in Figures 10 to 13.

[0030] The following embodiments are also within the scope of the present invention: the inkjet coating method as defined in claim 1 having the features of claim 2; the inkjet coating method as defined in claim 2 having the features of claim 3; the inkjet coating method as defined in claim 1 having the features of claim 4; the inkjet coating method as defined in claim 4 having the features of claim 5; the inkjet coating method as defined in any one of claims 1 to 5 having the features of claim 6; the inkjet coating method as defined in any one of claims 1 to 6 having the features of claim 7; the inkjet coating method as defined in any one of claims 1 to 7 having the features of claim 8; the inkjet coating method as defined in any one of claims 1 to 7 having the features of claim 9; the inkjet coating method as defined in any one of claims 1 to 9 having the features of claim 10; the inkjet coating method as defined in any one of claims 1 to 7 having the features of claim 11; the inkjet coating method as defined in any one of claims 1 to 7 having the features of claim 12; the inkjet coating method as defined in any one of claims 1 to 7 having the features of claim 13; the inkjet coating method as defined in any one of claims 1 to 13 having the features of claim 14; and the inkjet coating system having the features of claim 15.

[0031] 20 Gantry, 21 Vertical gantry, 22 Horizontal gantry, 30 Articulated robot, 40 Inkjet head, 60 Measuring unit, B Back door, P Object.

Claims

1. An inkjet coating method having a horizontal gantry having a plurality of downwardly mounted inkjet heads, and a vertical gantry to which the inkjet heads are mounted laterally, the horizontal gantry and the vertical gantry being movable horizontally relative to an object in a gantry coating step, and a robot coating step in which a plurality of articulated robots each having a plurality of the inkjet heads are installed.

2. The robot coating step is performed after the gantry coating step, and in the robot coating step, coating is performed on the object coated in the gantry coating step. The inkjet coating method according to claim 1.

3. In the robot coating step, coating is performed on a range not coated in the gantry coating step. The inkjet coating method according to claim 2.

4. The gantry coating step is performed after the robot coating step, and in the gantry coating step, coating is performed on the object coated in the robot coating step. The inkjet coating method according to claim 1.

5. In the gantry coating step, coating is performed on a range not coated in the robot coating step. The inkjet coating method according to claim 4.

6. Before the coating performed first among the gantry coating step and the robot coating step, the shape and position coordinates of the object are captured as data by 3D scanning the object, and are used for trajectory control of at least one of the gantry coating step and the robot coating step. The inkjet coating method according to claim 1.

7. Before the coating step performed later in the gantry coating step and the robot coating step, the coated range in the previous coating step is measured and the measurement range is captured as data, and is reflected in the trajectory control of the subsequent coating step. The inkjet coating method according to claim 6.

8. The horizontal gantry performs coating on the object from the front side of the object over the upper part to the rear side with the width direction of the object as the rotation axis. The inkjet coating method according to claim 1.

9. The vertical gantry performs coating on the coating object from one side over the front to the other side with the height direction as the rotation axis. The inkjet coating method according to claim 1.

10. The object on which ink is coated is an automobile. The inkjet coating method according to claim 1.

11. The inkjet coating method according to claim 10, wherein the horizontal gantry performs coating in a state where the back door of the automobile is flipped up.

12. The inkjet coating method according to claim 1, wherein at least one of the inkjets provided on the horizontal gantry and the vertical gantry is movable up and down in the height direction.

13. The inkjet coating method according to claim 12, wherein the inkjet is movable up and down in the height direction while maintaining a constant distance from the object.

14. The inkjet coating method according to claim 1, wherein at least one of the inkjet heads on the horizontal gantry and the vertical gantry is arranged in multiple rows and is arranged so as to shift the position with respect to the adjacent gantry.

15. An inkjet coating system having a horizontal gantry having a plurality of inkjet heads attached downward, a vertical gantry to which the inkjet heads are attached sideways, a gantry coating stage in which the horizontal gantry and the vertical gantry are relatively movable horizontally with respect to an object, and a robot coating stage in which a plurality of articulated robots having the inkjet heads are installed.

Images