Painting method

Abstract

To provide a coating method that can prevent an inner periphery of a coating material ejection port from being abraded and prevent a coating material from dripping, even when turning-on and off of spraying of a coating material are repeated.SOLUTION: In the coating method, a table 2 on which a work-piece 3 is mounted, a spray gun 5 that sprays a coating material, coating material supply means 13 that supplies the spray gun with a coating material are used. The spray gun comprises a coating material supply path having a coating material ejection port, atomization air supply path and a pattern air supply path. The coating material supply means comprises a coating material hose 14 connected to the coating material supply path and a syringe pump 15 connected to the coating material hose. The syringe pump comprises a syringe main body and a piston, which makes the piston advance to supply the spray gun with the coating material, supplies air to the atomization air supply path and the pattern air supply path to spray the coating material, stops supply of the coating material and the air when stopping the spraying of the coating material, and further makes the piston retract to return the coating material in the coating material supply path to the syringe pump side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a painting method, and more particularly, to a painting method in which paint is sprayed from a spray gun toward a workpiece to paint the workpiece.

Background Art

[0002] Generally, in painting a workpiece, paint is supplied to a spray gun and the supplied paint is sprayed from the spray gun toward the workpiece. And a conventional spray gun generally has a needle, and the spray and stop of the paint are performed by opening and closing a paint discharge port with this needle.

[0003] Referring to the drawings, a conventional spray gun will be described. FIG. 5 is a cross-sectional view for explaining the structure of the spray gun. In the figure, 51 is a spray gun. This spray gun 51 has a paint supply passage formed therein, receives the paint supplied from a paint supply means in this paint supply passage, and enables the received paint to be sprayed from a paint discharge port.

[0004] In the figure, 52 is a paint supply passage. This paint supply passage 52 has a paint receiving port 53 for receiving the paint supplied from the paint supply means and a paint discharge port 54 for injecting the paint received from this paint receiving port 53 toward the workpiece. The paint receiving port 53 is opened on the side wall side of the spray gun 51, and the paint discharge port 54 is opened at the tip end surface of the spray gun 51.

[0005] Next, in FIG. 5, 55 is a needle for opening and closing the paint discharge port 54. This needle 55 is movable in the front-rear direction of the spray gun 51, closes the paint discharge port 54 by moving forward, and opens the paint discharge port 54 by moving backward.

[0006] Here, a mechanism for moving the needle 55 in the longitudinal direction of the spray gun 51 will be described. In FIG. 5, the paint supply passage 52 extends from the paint discharge port 54 to the rear side of the spray gun 51 by an arbitrary distance, and then changes its path toward the side wall of the spray gun 51 and advances. A paint inlet 53 is opened on the side wall of the spray gun 51.

[0007] On the other hand, the needle 55 is disposed in the spray gun 51 so as to penetrate the central portion of the spray gun 51. The tip side is located in the paint supply passage 52, and the base end side protrudes from the paint supply passage 52 and out of the paint supply passage 52 inside the spray gun 51. A piston 56 that is movable back and forth in the spray gun 51 is fixed to the protruding portion. The piston 56 is biased toward the tip of the spray gun 51 by a spring 57. Thus, normally, the needle 55 moves toward the tip of the spray gun 51 together with the piston 56, and closes the paint discharge port 54 at the tip portion.

[0008] In addition, an air chamber 58 is formed inside the spray gun 51 on the side opposite to the spring side of the piston 56. A needle operating air supply passage 59 is formed in the air chamber 58, with its base end side opening on the side wall of the spray gun 51 and its tip side communicating with the air chamber 58. An air conveying means such as an air hose, to which an air supply means is connected at the base end side, is connected to the opening at the base end side of the needle operating air supply passage 59. By supplying air to the needle operating air supply passage 59 through the air conveying means, air is supplied into the air chamber 58, the piston 56 is pressed toward the base end side in the spray gun 51, and accordingly, the needle 55 moves toward the base end side of the spray gun 51, and the closing of the paint discharge port 54 by the tip of the needle 55 is released.

[0009] Therefore, it is possible to operate the needle 55 to open and close the paint discharge port 54 by supplying air to the air chamber 58 or discharging the supplied air.

[0010] Next, in the figure, 60 is the atomizing air supply passage, 61 is the pattern air supply passage. The atomizing air supply passage 60 is used to atomize the paint discharged from the paint discharge port 54 and spray it toward the workpiece. The pattern air supply passage 61 is used to change the ejection pattern of the paint atomized by the atomizing air into an arbitrary pattern.

[0011] And the atomizing air supply passage 60 has its tip opened at an arbitrary position around the paint discharge port 54. On the proximal end side, an atomizing air conveyance passage (not shown) is connected. When air is supplied through the atomizing air conveyance passage, atomizing air is supplied around the paint discharge port 54 through the atomizing air supply passage 60, enabling the paint discharged from the paint discharge port 54 to be atomized.

[0012] On the other hand, the pattern air supply passage 61 has its tip opened outside the tip opening of the atomizing air supply passage 60. On the proximal end side, a pattern air conveyance passage (not shown) is connected. When air is supplied through the pattern air conveyance passage, pattern air is supplied around the tip opening of the atomizing air supply passage 60 through the pattern supply passage 61, enabling the ejection pattern of the paint atomized by the atomizing air to be changed.

[0013] And when spraying paint toward the workpiece with the conventional spray gun 51 configured in this way, paint is supplied to the paint supply passage 52, air is supplied to the atomizing air supply passage 60 and the pattern air supply passage 61, and the needle 55 is further retracted. Then, the paint discharge port 54 is opened and the paint is discharged. This discharged paint is atomized by the atomizing air and sprayed toward the workpiece. Further, the ejection pattern is changed to a preset pattern by the pattern air and sprayed toward the workpiece.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

[0015] As described above, in the conventional spray gun, the discharge and stop of the paint are performed by opening and closing the paint discharge port with a needle. Therefore, it has been pointed out that the tip of the needle and the inner peripheral side of the paint discharge port that contacts the tip of the needle are likely to wear. And this is particularly noticeable when the on and off of the paint spraying are repeated because the contact between the tip of the needle and the inner peripheral side of the paint discharge port is repeated. Therefore, in the case of a spray gun used for painting that repeatedly turns the paint discharge on and off, the durability of the needle is particularly required, which has led to an increase in cost.

[0016] In addition, since wear occurs at the tip of the needle and the inner peripheral side of the paint discharge port caused by opening and closing the paint discharge port with a needle, it is conceivable that the pattern of the sprayed paint is disturbed as a result.

[0017] Furthermore, since there is variation in the way of wear at the tip of the needle and the inner peripheral side of the paint discharge port ( "uneven wear"), in the case of micro-discharge with little paint discharge or when using a plurality of spray guns, it is also conceivable that variation occurs in the discharge amount.

[0018] On the other hand, although spray guns without a needle have been conventionally provided, such spray guns produce paint dripping when the paint spraying is stopped during painting. Therefore, it is premised that the paint spraying is not stopped until the painting is completed once the painting of the workpiece is started, and it is not suitable for painting that repeatedly turns the paint spraying on and off during the painting of the workpiece.

[0019] Therefore, an object of the present invention is to provide a painting method that does not cause paint dripping even when the spraying of paint is repeatedly turned on and off during the painting of a workpiece.

Means for Solving the Problems

[0020] The painting method of the present invention is a work supply table on which a workpiece is mounted, a spray gun for spraying paint toward the workpiece mounted on the work supply table, and paint supply means for supplying paint to the spray gun, A painting system having and is a painting method for painting a workpiece by spraying the paint supplied to the spray gun toward the workpiece, as the spray gun, a main body, and formed inside the main body, at the tip, opening at the front end surface of the main body it has a paint discharge port, and at the base end, formed at the rear end of the main body there is a paint receiving portion connected a paint supply passage, a nebulizing air supply passage having an opening at an arbitrary position around the paint discharge port at the tip and an air receiving portion on the base end side, a pattern air supply passage having an opening outside the tip opening of the nebulizing air supply passage at the tip and a pattern air receiving portion on the base end side, having, without a needle, turning on and off the spraying of paint without opening and closing the paint discharge port by the needle using the spray gun, as the paint supply means, a paint supply hose whose tip is connected to the paint receiving portion of the spray gun, and a syringe pump for supplying paint to the spray gun via the paint supply hose, and the syringe pump includes a cylindrical syringe body formed with a paint discharge port to which the base end portion of the paint supply hose is connected, a piston slidably inserted into the syringe body, and a piston rod connected to the piston, and the piston can be advanced with the inside of the syringe body filled with paint to supply the paint in the syringe body to the spray gun, When spraying paint onto a workpiece, with the syringe body filled with paint, advance the piston to supply the paint in the syringe body to the spray gun. By supplying the paint in the syringe body to the spray gun, the paint is discharged from the paint discharge port formed at the tip side of the spray gun. At the same time, by supplying air to the atomizing air supply passage and the pattern supply passage, the paint discharged from the paint discharge port is atomized and sprayed onto the workpiece in an arbitrary pattern. When stopping the spraying of paint, stop the advancement of the piston to stop the supply of paint from the syringe pump, and stop the supply of air to the atomizing air supply passage and the pattern supply passage. Further, by retracting the piston , making the inside of the syringe body negative pressure, slightly reversing the paint remaining in the paint hose and the paint supply path back into the syringe body, and returning the liquid level of the paint at the paint discharge port to the paint supply path side This is the feature.

Effect of the Invention

[0021] The painting method of the present invention is a painting method for painting a workpiece by using a workpiece supply table on which the workpiece is mounted, a spray gun for spraying paint onto the workpiece mounted on the workpiece supply table, and a paint supply means for supplying paint to the spray gun, and spraying the paint supplied to the spray gun onto the workpiece.

[0022] And as the spray gun, it has a paint receiving portion on the proximal end side, and on the distal end side, a paint supply passage having a paint discharge port on the distal end side of the spray gun, a tip portion is opened at an arbitrary position around the paint discharge port, and an atomizing air supply passage provided with an air receiving portion on the proximal end side, and a pattern supply passage having a tip portion opened outside the tip opening of the atomizing air supply passage and provided with a pattern air receiving portion on the proximal end side, and uses a spray gun having these inside.

[0023] Furthermore, as the paint supply means, a paint supply hose whose tip is connected to the paint receiving part of the spray gun is used, and a syringe pump that supplies paint to the spray gun via the paint supply hose is used. The syringe pump includes a cylindrical syringe body formed with a paint discharge port to which the base end of the paint supply hose is connected, a piston that is inserted into the syringe body so as to be movable forward and backward, and a piston rod connected to the piston. By advancing the piston with the inside of the syringe body filled with paint, the paint in the syringe body can be supplied to the spray gun.

[0024] When spraying paint toward the workpiece, the paint in the syringe body is supplied to the spray gun by advancing the piston with the inside of the syringe body filled with paint, and the paint is discharged from the paint discharge port formed on the tip side of the spray gun. At the same time, by supplying air to the atomizing air supply passage and the pattern supply passage, the paint discharged from the paint discharge port is atomized and sprayed toward the workpiece in an arbitrary pattern. When stopping the spraying of the paint, the forward movement of the piston is stopped to stop the supply of paint from the syringe pump, and the supply of air to the atomizing air supply passage and the pattern supply passage is stopped. Further, the piston is retracted to slightly return the paint in the paint supply passage to the syringe pump side.

[0025] Therefore, unlike the conventional configuration, the spray gun used in the present invention does not use a needle. Therefore, even when repeatedly turning the spraying of the paint on and off, the inner peripheral side of the paint discharge port does not wear because it does not come into contact with the needle, and thus does not lead to an increase in cost.

[0026] Also, since the needle is not used, the tip of the needle and the inner peripheral side of the paint discharge port that comes into contact with the tip of the needle do not wear, so that it is possible to avoid the disturbance of the pattern of the paint to be sprayed, which is caused by wear.

[0027] Furthermore, since the tip of the needle and the inner peripheral side of the paint discharge port that comes into contact with the tip of the needle do not undergo uneven wear, there is an effect that even in the case of fine discharge with a small amount of paint discharge or when using a plurality of spray guns, there is no variation in the discharge amount.

[0028] And at this time, in the painting method of the present invention, when using a syringe pump as the paint supply means and stopping the spraying of the paint, the forward movement of the piston is stopped, the supply of air to the atomizing air supply path and the pattern supply path is stopped, and at the same time, the piston is retracted to slightly return the paint in the paint supply path to the syringe pump side. Therefore, when the spraying of the paint is stopped during painting, there is no dripping of the paint, and thus it is possible to sufficiently cope with even the case of painting where the spraying of the paint is repeatedly turned on and off during the painting of the workpiece.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0030] The painting method of the present invention is a painting method in which a workpiece is painted by spraying the paint supplied to a spray gun toward the workpiece using a workpiece supply table on which the workpiece is mounted, a spray gun for spraying the paint toward the workpiece mounted on this workpiece supply table, and a paint supply means for supplying the paint to this spray gun.

[0031] And as for the spray gun, a main body and formed inside this main body, at the tip, opening at the front end surface of the main body it has a paint discharge port, and at the base end, formed at the rear end of the main body there is a paint receiving portion connected a paint supply path, a atomizing air supply path with the tip opened at an arbitrary position around the paint discharge port and an air receiving portion provided on the base end side, and a pattern air supply path with the tip opened outside the tip opening of the atomizing air supply path and a pattern air receiving portion provided on the base end side, having, without a needle, turning on and off the spraying of paint without opening and closing the paint discharge port by the needle is used.

[0032] Also, as the paint supply means, a paint supply hose having a tip connected to the paint receiving portion of the spray gun and a syringe pump for supplying paint to the spray gun through this paint supply hose are used. The syringe pump includes a cylindrical syringe body formed with a paint discharge port to which the base end portion of the paint supply hose is connected, a piston slidably inserted into the syringe body, and a piston rod connected to the piston. By advancing the piston with the inside of the syringe body filled with paint, the paint inside the syringe body can be supplied to the spray gun.

[0033] And in the painting method of the present invention, when spraying paint toward the workpiece, the piston is advanced with the inside of the syringe body filled with paint to supply the paint inside the syringe body to the spray gun, so that the paint is discharged from the paint discharge port formed on the tip side of the spray gun, and by supplying air to the atomizing air supply path and the pattern supply path, the paint discharged from the paint discharge port is atomized and sprayed toward the workpiece in an arbitrary pattern. When stopping the spraying of the paint, the forward movement of the piston is stopped to stop the supply of the paint from the syringe pump, and the supply of air to the atomizing air supply path and the pattern supply path is stopped. Further, the piston is retracted to slightly return the paint in the paint supply path to the syringe pump side.

[0034] Here, workpiece supply TableIt is preferably a rotatable turntable that enables a plurality of workpieces to be attached along the circumferential direction in the vicinity of the outer peripheral portion. Thereby, it is possible to paint a large number of workpieces with a small amount of paint.

[0035] Further, a filling port may be formed in the piston constituting the syringe pump, and a filling passage communicating with this filling port may be formed in the piston rod. Thereby, it becomes easy to fill the paint into the syringe body.

Example

[0036] An example of the painting method of the present invention will be described. FIG. 1 is a diagram showing an image of a painting system for carrying out the painting method of this example. In the figure, 1 is a painting system for carrying out the painting method of this example.

[0037] And in the painting system 1 shown in the figure, it is a system having a work supply table with a workpiece attached, a spray gun for spraying paint toward the workpiece attached to this work supply table, and further a paint supply means for supplying paint to the spray gun.

[0038] That is, in the figure, 2 is the work supply table, and 3 is the workpiece attached to the work supply table 2. The work supply table 2 used in this example is in the shape of a disk, is connected to the upper part of the main shaft 4, and is a turntable that is rotatable along with the rotation of the main shaft 4. And in this example, eight workpieces 3 are attached at equal intervals along the circumferential direction in the vicinity of the outer peripheral portion of the turntable 2.

[0039] The method of rotating the main shaft 4 is not particularly limited, but a method of connecting to a driving means such as a motor and rotating the main shaft 4 by driving the driving means such as a motor can be considered. Further, the method of attaching the workpiece 3 to the turntable 2 is not particularly limited, and a method of detachably locking the workpiece 3 to the turntable 2 using a jig can be considered.

[0040] Next, in the figure, reference numeral 5 denotes a spray gun for spraying paint onto a workpiece attached to the turntable to paint the workpiece, and reference numeral 13 denotes paint supply means for supplying paint to the spray gun 5.

[0041] Here, referring to FIG. 2 for the spray gun 5, FIG. 2 is a cross-sectional view for explaining the structure of the spray gun 5. In the figure, the spray gun 5 has a main body portion 6, and a paint supply passage 7 is formed inside the main body portion 6. The tip of the paint supply passage 7 opens at the tip surface of the main body portion 6, and this opened portion serves as a paint discharge port 8.

[0042] Next, in the figure, reference numeral 9 denotes a hose joint 9 as a paint receiving portion. That is, a hose joint 9 is formed at the rear end portion of the main body portion 6, and the base end portion of the paint supply passage 7 is connected to this hose joint 9. Further, in FIG. 1, reference numeral 14 denotes a paint supply hose. The tip of this paint supply hose 14 is connected to the hose joint 9, whereby paint is supplied to the spray gun 5 via the paint supply hose 14, and the supplied paint can be discharged from the paint discharge port 8.

[0043] Also, in the figure, reference numeral 10 denotes an atomizing air supply passage, and reference numeral 11 denotes a pattern air supply passage. That is, similar to the conventional spray gun described above, the spray gun 5 used in this embodiment also has an atomizing air supply passage 10 and a pattern air supply passage 11. The atomizing air supply passage 10 is used to atomize the paint discharged from the paint discharge port 8 and spray it toward the workpiece, and the pattern air supply passage 11 is used to change the ejection pattern of the paint atomized by the atomizing air into an arbitrary pattern.

[0044] The tip of the atomizing air supply passage 10 is opened at an arbitrary position around the paint discharge port 8, and an air conveyance passage (not shown) is connected to the base end side. When air is supplied through the air conveyance passage, atomizing air is supplied around the paint discharge port 8 through the atomizing air supply passage 10, making it possible to atomize the paint discharged from the paint discharge port 8.

[0045] Further, the pattern air supply passage 11 has an opening at its tip outside the tip opening of the atomizing air supply passage 10, and an air conveyance passage (not shown) is connected to the base end side. When air is supplied through the air conveyance passage, pattern air is supplied to the periphery of the tip opening of the atomizing air supply passage 10 through the pattern supply passage 13, making it possible to change the ejection pattern of the paint atomized by the atomizing air.

[0046] In the figure, reference numeral 12 denotes an air supply unit. The tip of an air hose is connected to this air supply unit 12, and the tip side is connected to an air conveyance passage (both not shown), whereby air can be supplied to the atomizing air supply passage 10 and the pattern air supply passage 11.

[0047] In the figure, reference numeral 30 denotes a mounting portion to which mounting screws are connected. The spray gun 5 is connected to the painting apparatus through this mounting portion 29.

[0048] In the spray gun 5 configured as described above, when paint is supplied to the paint supply passage 7 and air is supplied to the atomizing air supply passage 10 and the pattern air supply passage 11, the paint is discharged from the paint discharge port 8, and the discharged paint is atomized by the atomizing air and sprayed toward the workpiece. Further, the ejection pattern is changed to a preset pattern by the pattern air and sprayed toward the workpiece.

[0049] Next, the paint supply means 13 for supplying paint to the spray gun 5 configured as described above will be described. In FIG. 1, reference numeral 13 denotes the paint supply means. The paint supply means 13 used in the painting method of the present embodiment includes a syringe pump 15 and a paint supply hose 14 connecting the syringe pump 15 and the spray gun 5. The tip of the paint supply hose 14 is connected to the hose joint 9 of the spray gun 5 as described above, and the base end side is connected to the syringe pump 15. A paint supply valve 16 is attached to an arbitrary position of the paint hose 14.

[0050] Here, referring to FIG. 3, the syringe pump 15 will be described. In the figure, 15 is the syringe pump. The syringe pump 15 has a cylindrical syringe body 17 with a paint discharge port 18 to which the proximal end portion of the paint supply hose 14 is connected formed at the distal end portion. Inside this syringe body 17, a piston 19 is inserted so as to be movable forward and backward, and a piston rod 21 is connected to the surface of the piston 19 on the side opposite to the paint discharge port. By advancing the piston 19 with the inside of the syringe body 17 filled with paint, the paint inside the syringe body 17 can be supplied to the spray gun 5 via the paint supply hose 14.

[0051] Also, the piston 19 is formed with a paint filling port 20 penetrating in the forward and backward direction. On the other hand, inside the piston rod 21, a paint filling passage 22 is formed which penetrates the piston rod 21 in the axial direction and is continuous with the paint filling port 20 formed in the piston 19. One end of a paint filling hose 23 is connected to the paint filling passage 22. The paint filling hose 23 has its proximal end connected to a paint tank 25, and a filling valve 24 and a filling pump 31 are arranged in the middle of the path.

[0052] Here, the mechanism for moving the piston 19 forward and backward will be described. In FIG. 3, in this embodiment, an operating plate 26 is attached to the piston rod 21, and the operating plate 26 is connected to a ball screw 27. This ball screw 27 is connected to the shaft of a motor 29 as a driving means. With this configuration, by driving the motor 29 and rotating the ball screw 27, the operating plate 26 is reciprocated at a constant speed along the screw shaft 28 of the ball screw 27, and thereby, via the piston rod 21, the piston 19 can be moved forward and backward inside the syringe body 17. However, it is not necessarily required to adopt the above-described mechanism as the mechanism for moving the piston 19 forward and backward, and any method may be adopted as long as the piston 19 can be moved forward and backward.

[0053] Next, when filling the syringe body 17 with paint in the painting system configured as described above, with the paint supply valve 16 closed, the paint filling valve 24 is opened and the motor 29 is driven to pull the piston 19 toward the anti-paint discharge port side. Then, the inside of the syringe body 17 becomes negative pressure, and since the paint supply valve 16 is closed, the paint in the paint tank 25 is filled into the syringe body 17 through the paint filling hose 23, the paint filling passage 22, and the paint filling port 20.

[0054] And when the piston 19 has been pulled by a predetermined distance, the motor 29 is stopped to stop pulling the piston 19, and the paint filling valve 24 is closed. Then, it becomes possible to fill the inside of the syringe body 17 with the required amount of paint.

[0055] Next, the case of painting a workpiece using the painting system 1 configured as described above will be described with reference to the flowchart of FIG. 4. When painting a workpiece in this embodiment, first, in S1, the syringe body 17 is filled with paint by the method described above. After the filling is completed, in S2, the motor 28 is stopped to stop pulling the piston 19 and the paint filling valve 24 is closed to complete the filling.

[0056] Next, when spraying paint, with the syringe body 17 filled with paint by the method described above, in S3, the paint supply valve 16 is opened, and in S4, the piston 19 is advanced by the mechanism described above, whereby the paint is discharged from the paint discharge port 18 of the syringe body 17 into the paint hose 14. Then, the paint is supplied to the paint supply passage 7 through the hose joint 9 of the spray gun 5, and the supplied paint is discharged from the paint discharge port 8.

[0057] On one hand, as the piston 19 advances, in S5, air is supplied to the atomizing air supply passage 10 and the pattern air supply passage 11. Thereby, paint is discharged from the paint discharge port 8, atomizing air is supplied around the paint discharge port 8, and further, pattern air is supplied outside the tip opening of the atomizing air supply passage 10. Then, the paint discharged from the paint discharge port 8 is atomized by the atomizing air and sprayed toward the workpiece, and further, the ejection pattern is changed to a preset pattern by the pattern air and sprayed toward the workpiece in S6. When continuing painting, S4, 5, and 6 are repeated.

[0058] Next, the case where painting is completed or the spraying of paint is stopped for other reasons will be described. When stopping the spraying of paint, in S7, the advancement of the piston 19 is stopped to stop the supply of paint from the syringe pump 15, and the supply of air to the atomizing air supply passage 10 and the pattern air supply passage 11 is stopped, thereby stopping the spraying of paint and stopping the painting of the workpiece.

[0059] And in this embodiment, further, in S8, inside the syringe body 17, the piston 19 is slightly retracted. Thereby, the inside of the syringe body 17 is made into a negative pressure, and the paint remaining in the paint hose 14 and the paint supply passage 7 is slightly backflowed and returned into the syringe body 17. Then, the liquid level of the paint at the paint discharge port 8 can be returned to the paint supply passage 7 side, so it is possible to effectively prevent paint leakage from the paint discharge port 8. When restarting the paint painting thereafter, return to S4, and repeat S4, 5, and 6 until the spraying of paint is stopped.

[0060] Thus, in the painting method of this embodiment, since a spray gun not equipped with a needle is used, unlike the conventional spray gun that opens and closes the paint discharge port with a needle, even when repeatedly turning the spraying of paint on and off, there is no wear of the needle, so it does not lead to an increase in cost.

[0061] In addition, since the tip of the needle and the inner peripheral side of the paint discharge port that comes into contact with the tip of the needle do not wear, it is possible to avoid the disturbance of the pattern of the sprayed paint that occurs due to wear. Furthermore, even in the case of micro-discharge with a small amount of paint discharge or when using a plurality of spray guns, it is possible to prevent variations in the discharge amount.

[0062] And at this time, in the painting method of this embodiment, when using the syringe pump 15 as the paint supply means and stopping the spraying of the paint, the forward movement of the piston 19 is stopped, and the supply of air to the atomizing air supply passage 10 and the pattern air supply passage 11 is stopped. Furthermore, after that, the piston 19 is slightly retracted to slightly return the paint in the paint supply passage 7 to the syringe pump 15 side. Therefore, when the spraying of the paint is stopped during painting, there is no occurrence of paint dripping. Thus, it is possible to sufficiently cope with even the case of painting where the spraying of the paint is repeatedly turned on and off during the painting of the workpiece.

Industrial Applicability

[0063] The painting method of the present invention is a painting method using a spray gun that does not include a needle, and is characterized in that when the spraying of the paint is stopped, the paint in the spray gun is returned to the paint supply means side. Therefore, it is applicable to the overall painting of workpieces using spray guns.

Explanation of Reference Numerals

[0064] 1 Painting system 2 Turntable 3 Workpiece 4 Main shaft 5 Spray gun 6 Body part 7 Paint supply passage 8 Paint discharge port 9 Hose joint 10 Atomizing air supply passage 11 Pattern air supply passage 12 Air supply unit 13 Paint supply means 14 Paint supply hose 15 Syringe pump 16 Paint supply valve 17 Syringe body 18 Paint discharge port 19 Piston 20 Paint filling port 21 Piston rod 22 Paint filling path 23 Paint filling hose 24 Filling valve 25 Paint tank 26 Actuating plate 27 Ball screw 28 Screw shaft 29 Motor 30 Mounting part 31 Pump

Claims

1. A work supply table (2) with a work (3) attached thereto, A spray gun (5) for spraying paint toward the work (3) attached to the work supply table (2), Paint supply means (13) for supplying paint to the spray gun (5), Using a painting system (1) having the above, a painting method for painting the work (3) by spraying the paint supplied from the paint supply means (13) to the spray gun (5) toward the work (3), As the spray gun (5), A main body portion (6), Formed inside the main body portion (6), At the tip portion, it has a paint discharge port (8) that opens at the front end surface of the main body portion (6), and at the base end portion, a paint supply path (7) to which a paint receiving portion (9) formed at the rear end portion of the main body portion (6) is connected, The tip portion is opened at an arbitrary position around the paint discharge port (8), and the atomizing air supply path (10) having an air receiving portion on the base end side, The tip portion is opened outside the tip opening portion of the atomizing air supply path (10), and the pattern air supply path (11) having a pattern air receiving portion on the base end side, Having, without providing a needle, using a spray gun (5) that turns the spraying of paint on and off without opening and closing the paint discharge port (8) by a needle, As the paint supply means (13), A paint supply hose (14) whose tip portion is connected to the paint receiving portion (9) of the spray gun (5), A syringe pump (15) for supplying paint to the spray gun (5) via the paint supply hose (14), and at the same time, The syringe pump (15) includes a cylindrical syringe body (17) formed with a paint discharge port (18) to which the base end portion of the paint supply hose (14) is connected, A piston (19) inserted into the syringe body (17) so as to be movable forward and backward, A piston rod (21) connected to the piston (19), By advancing the piston (19) with the inside of the syringe body (17) filled with paint, the paint inside the syringe body (17) can be supplied to the spray gun (5), When spraying paint toward the workpiece (3), the paint in the syringe body (17) is supplied to the spray gun (5), so that the paint is discharged from the paint discharge port (8) formed on the tip side of the spray gun (5). At the same time, by supplying air to the atomizing air supply passage (10) and the pattern supply passage (11), the paint discharged from the paint discharge port (8) is atomized and sprayed toward the workpiece (3) in an arbitrary pattern. When stopping the spraying of paint, the forward movement of the piston (19) is stopped to stop the supply of paint from the syringe pump (15). At the same time, the supply of air to the atomizing air supply passage (10) and the pattern supply passage (11) is stopped. Further, by retracting the piston (19), the inside of the syringe body (17) is made negative pressure, and the paint remaining in the paint hose (14) and the paint supply passage (7) is slightly reversed and returned to the syringe body (17), so that the liquid level of the paint at the paint discharge port (8) is returned to the paint supply passage (7) side. A painting method characterized by this.

2. The painting method according to claim 1, characterized in that the workpiece supply table (2) is a rotatable turntable that can attach a plurality of workpieces (3) along the circumferential direction in the vicinity of the outer peripheral portion.

3. The painting method according to claim 1 or claim 2, characterized in that a paint filling port (20) is formed in the piston (19) constituting the syringe pump (15), and a paint filling passage (22) communicating with the paint filling port (20) is formed in the piston rod (21).

Images