Coating system and method for producing automobile

Abstract

[Problem] To control the thickness of a coating film when coating an object to be coated that has an angle. [Solution] The present invention is a coating system that comprises an inkjet head 40 which applies a coating material and that uses the inkjet head to coat an object bj to be coated which has a curvature, wherein the inkjet head changes the number of drops to be discharged via multi-drop discharge in accordance with the curvature of the object to be coated and changes the discharge amount.

Description

Coating system and automobile manufacturing method

[0001] The present invention relates to an application system and a method for manufacturing an automobile.

[0002] The same automobile can be divided into many different types depending on the paint coating. Conventional painting techniques have been proposed to change the ink ejection amount or ejection interval of an ink jet print head depending on the amount of change in the distance between the ink jet print head and the print medium.

[0003] Japanese Patent Application Publication No. 9-193368

[0004] The present inventors have been conducting extensive research into the thickness of a coating film when an angled object is coated using an inkjet head.

[0005] An object of the present invention is to control coating thickness when coating an angled substrate.

[0006] One aspect of the present invention is a system having an inkjet head for applying paint, which applies paint to a curvature-bearing object using the inkjet head. The inkjet head is configured to vary the number of droplets ejected by multi-drop and thus the ejection amount depending on the curvature of the object. Another aspect of the present invention is a method for manufacturing an automobile having an inkjet head for applying paint, which applies paint to a curved vehicle body using the inkjet head, and which varies the number of droplets ejected by multi-drop and thus the ejection amount depending on the curvature of each part of the vehicle body during the application.

[0007] According to the coating system and automobile manufacturing method described above, it is possible to control the thickness of the coating film when coating an object having an angle.

[0008] FIG. 1 is a block diagram of devices constituting a coating system according to an embodiment. FIG. 2 is a schematic diagram showing how the amount of paint droplets ejected is varied depending on the shape of a part. FIG. 3 is a schematic diagram showing how the number of droplets per cycle is varied by waveform control. FIG. 4 is a schematic diagram showing how the amount of droplets ejected is varied depending on the nozzle of an inkjet head. FIG. 5 is a schematic diagram showing different coating thicknesses for different parts of an object to be coated. FIG. 6 is a schematic diagram showing how droplets are ejected from an inkjet head in a variable amount depending on the part of an object to be coated. FIG. 7 is a schematic diagram illustrating examples of applications of the coating system.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations will be omitted. In the drawings, the size and proportions of each component are exaggerated to facilitate understanding of the embodiments, and may differ from the actual size and proportions.

[0010] Fig. 1 is a block diagram showing the configuration of a coating system 1 according to an embodiment. Fig. 2 is a schematic diagram showing how the droplets d of paint to be ejected are varied depending on the shape of a part. Fig. 3 is a schematic diagram showing how the droplet volume per cycle is varied by waveform control. Fig. 4 is a schematic diagram showing how the droplets d to be ejected are varied depending on the nozzle of an inkjet head 40.

[0011] Fig. 5 is a schematic diagram showing different coating thicknesses for different parts of the workpiece bj. Fig. 6 is a schematic diagram showing how droplets d are variably ejected from the inkjet head 40 for different parts of the workpiece bj. Fig. 7 is a schematic diagram showing examples of applications of the coating system 1.

[0012] The inkjet coating system 1 according to this embodiment can be used in the coating process of a curvature-bearing object bj, such as a car body, in a manufacturing method of an automobile v1 as shown in Fig. 7. As shown in Fig. 1, the inkjet coating system has an information acquisition unit 10, a calculation unit 20, a storage unit 30, and an inkjet head 40. These will be described in detail below.

[0013] The information acquisition unit 10 is configured to acquire information about the object bj to be painted, such as a car body. The information acquisition unit 10 may include a sensor for detecting the position of the surface of the car body that is the object bj to be painted, a known camera for capturing an image of a predetermined range, etc. The data acquired by the information acquisition unit 10 can be stored in a storage unit 30, which will be described later.

[0014] The calculation unit 20 is configured to perform calculations on data of the application area included in the image, etc., that can be acquired by the information acquisition unit 10 and stored in the storage unit 30. That is, the calculation unit 20 identifies a surface area of ​​the part that is located on an extension line of the nozzle of the inkjet head 40 in the acquired image of the object, and calculates the curvature and angle between that area and the inkjet head 40.

[0015] To calculate the curvature, the memory unit 30 can store a surface image of the object bj, such as a part, acquired by the information acquisition unit 10. Therefore, the calculation unit 20 generates an extension line of the nozzle of the inkjet head 40, sets the intersection of the extension line and the object bj to be a tangent point, and calculates the curvature of the tangent point. Furthermore, the angle is calculated by calculating the angle formed by the tangent line to the surface of the object bj at the intersection of the extension line of the nozzle of the inkjet head 40 and the object bj, and a horizontal line, a vertical line, etc. The calculation unit 20 includes a CPU, etc., and the memory unit 30 includes RAM, ROM, HDD, SSD, etc.

[0016] In this embodiment, the calculation unit 20 controls the number of droplets d of paint ejected from the inkjet head 40 to vary depending on the curvature of the workpiece bj. By configuring in this way, it is possible to apply paint with approximately the same coating thickness regardless of the shape of the workpiece bj, such as a curved part like the part P1 shown in Figure 2 or a concave part like the part P2.

[0017] In this embodiment, the amount of droplets d is varied by controlling the number of droplets discharged per cycle of the discharge frequency, as shown in Figure 3. This waveform control changes the amount of droplets per cycle, making it possible to appropriately control the thickness of the coating film for each location, as described below. The range of variation in droplets d can be set to, for example, 1 to 8 droplets.

[0018] The storage unit 30 can store, for example, data on values ​​obtained by dividing the curvature value into a certain range and the corresponding number of droplets d. The number of droplets d can be configured to increase as the curvature value increases. The relationship between the curvature and droplets d can be configured such that the curvature value is divided into a range of certain values, and the number of droplets d increases stepwise depending on the size of the range. By configuring in this way, it is possible to form a coating film with a substantially uniform thickness on a part having a curvature.

[0019] In this embodiment, the inkjet head 40 is configured to eject droplets by varying the amount of droplets using piezoelectric drive, as shown in FIG. 4. That is, the inkjet head 40 is configured to eject droplets by expanding and contracting a piezoelectric element disposed in a liquid chamber. This configuration makes it possible to change the amount (number) of droplets d ejected from each nozzle. The paint ejected by the inkjet head 40 can be used for primer paint, intermediate paint, top coat paint, etc. The inkjet head 40 has multiple nozzles that eject paint, and the nozzles can be arranged, for example, in multiple rows or multiple columns.

[0020] The droplets d ejected from the inkjet head 40 can be merged during flight or before adhering to the workpiece bj, thereby allowing the ejection amount to be varied by an integer multiple. For example, when droplets d are ejected at relatively short intervals, the leading droplet d experiences air resistance and becomes the slowest, and the droplets merge to form a large droplet d. Furthermore, since there is no need to narrow the ejection interval, the scanning speed of the inkjet head 40 is not affected.

[0021] The inventors discovered that when coating an object bj that is at an angle to the ejection direction of the inkjet head, the coating film in the area where the contact area between the object bj and the droplet d is large becomes thinner, like coating film m2 compared to coating film m1 (see Figure 5). The thickness of the paint applied to the object can be on the order of micrometers.

[0022] 6, the calculation unit 20 varies the amount of droplets d to be ejected depending on the curvature of the area where droplets d are to be ejected, so that relatively small droplets d are ejected from the inkjet head 40 onto areas with small angles. Furthermore, droplets d are ejected continuously onto areas with relatively large angles, so that relatively large droplets d are ejected. This allows the thickness of the coating to be formed approximately uniformly, even though it can vary by about twice as much if droplets d were ejected regardless of the area.

[0023] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the claims. In the above, the information acquisition unit 10 has a camera or the like, and captures an image of the actual surface of the workpiece bj to be painted, and calculates the curvature, etc., for each part. However, the information acquisition unit may also have a keyboard, a mouse, etc., and the storage unit may store an application such as CAD, and the curvature, etc., may be calculated from CAD data, etc., of the workpiece bj.

[0024] The following embodiments are also within the scope of the present invention: an application system according to claim 1 having the features of claim 2; an application system according to claim 1 or claim 2 having the features of claim 3; an application system according to any one of claims 1 to 3 having the features of claim 4; and a method for manufacturing an automobile having the features of claim 5.

[0025] 1 Coating system, 40 Inkjet head, bj Object to be coated, d Droplet, m1, m2 Coating film, v1 Automobile.

Claims

1. A coating system having an inkjet head for applying a coating material, and applying the coating material to a coated object having a curvature using the inkjet head, wherein the inkjet head varies the number of droplets ejected by multi-drop according to the curvature of the coated object and varies the ejection amount.

2. The coating system according to claim 1, wherein the inkjet head ejects droplets by piezo drive.

3. The coating system according to claim 1 or 2, wherein the ink droplets variably control the number of ejected droplets per cycle of the ejection frequency.

4. The coating system according to claim 1 or 2, wherein the inkjet head varies the droplet amount for each nozzle in the inkjet head according to the curvature of the coated object.

5. A method for manufacturing an automobile, which has an inkjet head for applying a coating material, applies the coating material to a vehicle body having a curvature using the inkjet head, and in the application, varies the number of droplets ejected by multi-drop according to the curvature of each part of the vehicle body and varies the ejection amount.

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