Powder coating equipment

Abstract

To provide a powder coating applicator which can remove extra transport air from flying air for flying a powder coating from an electrostatic coating gun to a coated object and spray the powder coating to the coated object with a minimum proper amount of the flying air and achieves good application efficiency.SOLUTION: In a powder coating applicator, a powder coating A in a coating tank 2 is suctioned by an injector 5 into which compressive air is loaded, and the compressive air is made into transport air to transport the powder coating A to an electrostatic coating gun 3 through a coating hose 9. Then, the powder coating A is jetted from the electrostatic coating gun 3 to a coated object B and adhered to the coated object B by electrostatic force. A cyclone 10 which separates the powder coating A and the transport air from multi-phase flow of the powder coating A and the transport air passing through the coating hose 9 is installed at a downstream side end of the coating hose 9. The powder coating A separated from the transport air by the cyclone 10 is supplied to the electrostatic coating gun 3 by a second injector 11.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a powder coating apparatus that injects powder coating material from an electrostatic coating gun onto an object to be coated, and causes the powder coating material to adhere to the object to be coated by electrostatic force.

Background Art

[0002] Conventionally, as shown in Figure 2, a known powder coating apparatus sucks powder coating material A in a coating material tank 20 by an injector 21 into which compressed air is introduced, conveys the powder coating material A to an electrostatic coating gun 23 via a coating material hose 22 using the compressed air introduced into the injector 21 as conveying air, injects the powder coating material A from the electrostatic coating gun 23 onto an object B to be coated, and causes the powder coating material A to adhere to the object B to be coated by electrostatic force (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problem to be Solved by the Invention

[0004] By the way, as described above, when the powder coating material A is sucked by the injector 21 and conveyed to the electrostatic coating gun 23 by the conveying air via the coating material hose 22, in order to convey the powder coating material A to the electrostatic coating gun 23 without clogging inside the coating material hose 22, the flow rate of the conveying air needs to be increased according to the path length of the coating material hose 22.

[0005] The conveying air that conveys the powder coating material A from the coating material tank 20 to the electrostatic coating gun 23 also includes flight air that causes the powder coating material A to fly from the electrostatic coating gun 23 to the object B to be coated.

[0006] Therefore, if the flow rate of the conveying air is large, the amount of air used to propel the powder coating A from the electrostatic coating gun 23 to the object B also increases. The force of this air exceeds the electrostatic force that causes the powder coating A to adhere to the object B, and the air blows away the powder coating A that is adhering to the object B, resulting in poor coating efficiency of the powder coating A that adheres to the object B.

[0007] Therefore, this invention aims to provide a powder coating apparatus with good coating efficiency that removes excess transport air from the air used to propel the powder coating from the electrostatic coating gun to the workpiece, and allows the powder coating to be sprayed onto the workpiece with the minimum necessary and appropriate amount of air. [Means for solving the problem]

[0008] To solve the aforementioned problems, this invention provides a powder coating apparatus in which powder coating is drawn in from a paint tank by an injector into which compressed air is introduced, transported through a paint hose using the compressed air introduced into the injector as transport air to an electrostatic coating gun, and the powder coating is sprayed from the electrostatic coating gun onto the object to be coated, causing the powder coating to adhere to the object by electrostatic force. In this apparatus, a cyclone is installed at the downstream end of the paint hose to separate the powder coating from the transport air from the multiphase flow of powder coating and transport air passing through the paint hose, and the powder coating separated from the transport air by this cyclone is supplied to the electrostatic coating gun by a second injector.

[0009] Alternatively, the cyclone may be used to remove small-particle powder paint along with the conveying air. [Effects of the Invention]

[0010] According to the powder coating apparatus of this invention, a cyclone installed at the downstream end of the paint hose separates the powder coating from the transport air in a multiphase flow, and the powder coating separated from the transport air is supplied to the electrostatic coating gun by a second injector. By limiting the amount of air from the second injector to the minimum necessary to pass through the electrostatic coating gun and reach the workpiece, it is possible to prevent the amount of air passing through the electrostatic coating gun from exceeding the adhesion force of the powder coating due to electrostatic force, thereby improving the coating efficiency of the powder coating to the workpiece.

[0011] Furthermore, the cyclone separates the transport air and removes small-particle-sized powder coatings that are difficult to adhere to the object being coated, thereby further improving coating efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing a powder coating apparatus according to the present invention. [Figure 2] This is a schematic diagram showing a conventional powder coating apparatus. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the powder coating apparatus of this invention will be described based on the attached drawings.

[0014] The powder coating apparatus shown in Figure 1 is used to paint an object B to be coated by spraying powder paint A from a paint tank 2 onto the object B inside a paint booth 1 using an electrostatic paint gun 3.

[0015] As the electrostatic coating gun 3, a corona electrostatic coating gun equipped with a corona electrode at the tip of the gun, or a triboelectric electrostatic coating gun equipped with a friction tube inside the gun body can be used.

[0016] Paint booth 1 is equipped with a recovery duct 4 for collecting overspray powder that did not adhere to the object B being painted.

[0017] The paint tank 2 is of a fluidized type, which has a perforated plate 2a on the bottom surface and supplies fluidizing air 2b from the lower surface of the perforated plate 2a. The fluidized paint tank 2 can break up clumps of the powder paint A in the paint tank 2 by the fluidizing air 2b and perform dehumidification at the same time.

[0018] A discharge port 2c for the powder paint A is provided at the lower part of the paint tank 2 that stores the powder paint A, and a constant-volume supply device 6 is installed between this discharge port 2c and the injector 5.

[0019] The constant-volume supply device 6 includes a relay tank 7 connected to the discharge port 2c of the paint tank 2, and a screw feeder unit 8 provided at the lower portion of the relay tank 7.

[0020] Inside the relay tank 7, a net 7b that is vibrated by a vibrator 7a is stretched to release excess air between the powder paints A and make the amount of the powder paint A per unit volume constant. An air discharge port 7c is provided on the upper surface of the relay tank 7.

[0021] The screw feeder unit 8 includes a screw guide 8a having a supply port on the upper surface and a discharge port at the front end, and a screw 8b accommodated in the screw guide 8a.

[0022] The rear end of the screw shaft of the screw 8b penetrates through the screw guide 8a and is connected to a motor 8c installed on the rear wall of the relay tank 7.

[0023] Further, the front end of the screw shaft of the screw 8b is rotatably supported by the front end wall of the screw guide 8a.

[0024] The discharge port at the front end of the screw guide 8a is connected to a discharge passage 8d that is connected to the suction port 5a of the injector 5.

[0025] A rectifier plate 8e is provided at the discharge port of the screw guide 8a so as to be openable and closable by a spring. The powder coating A is continuously pressed against the rectifier plate 8e by the rotation of the screw 8b, and the powder coating A is supplied from the discharge port to the discharge port passage 8d.

[0026] An injector 5 is installed below the discharge passage 8d located at the front end of the screw feeder unit 8.

[0027] An air supply pipe 5b is connected to the injector 5, and the conveying air blown in from this air supply pipe 5b sucks the powder coating A from the suction port 5a on the top surface and conveys the powder coating A through the paint hose 9 towards the electrostatic coating gun 3.

[0028] The transport air supplied to the injector 5 via the air supply pipe 5b is controlled by the control panel. The electrostatic painting gun 3 and the screw feeder unit 8 are also controlled by the control panel.

[0029] A cyclone 10 is installed at the downstream end of the paint hose 9 to separate the powder paint A from the conveying air from the multiphase flow of powder paint A and conveying air passing through the paint hose 9.

[0030] The cyclone 10 is a device that flows powder paint A into a funnel-shaped or cylindrical cyclone body 10a along with conveying air in a swirling motion, exhausts the conveying air upward from the center of the circle of the cyclone body 10a, centrifugally separates the powder paint A, causes the separated powder paint A to collide with the walls of the cyclone body 10a, and then accumulates the powder paint A at the bottom of the cyclone body 10a due to gravity.

[0031] A second injector 11 is installed at the bottom of the cyclone body 10a, and compressed air 11a supplied to this second injector 11 sucks up the powder paint A accumulated at the bottom of the cyclone body 10a, causing the powder paint A to be sprayed from the electrostatic painting gun 3 toward the object to be painted B.

[0032] The compressed air 11a supplied to the second injector 11 is controlled to be the minimum amount of air necessary to pass through the electrostatic painting gun 3 and reach the object to be painted B, thereby reducing the blowing away of the powder coating A that adheres to the object to be painted B due to electrostatic force.

[0033] The exhaust from the cyclone 10 is drawn into the bag filter 13 by the exhaust fan 12. The exhaust from the cyclone 10 contains powder coating A with small particle size that is difficult to adhere to the object to be coated B, and this powder coating A with small particle size is collected by the bag filter 13. The collected exhaust from the cyclone 10 is then exhausted into the room via the secondary filter 14.

[0034] As described above, in the powder coating apparatus shown in Figure 1, the cyclone 10 installed at the downstream end of the paint hose 9 separates the powder coating A from the transport air from the multiphase flow of the powder coating A and the transport air. The powder coating A separated from the transport air is supplied to the electrostatic coating gun 3 by the second injector 11. By limiting the amount of air from the second injector 11 to the minimum necessary to pass through the electrostatic coating gun 3 and reach the workpiece B, the blowing away of the powder coating A that adheres to the workpiece B due to electrostatic force by the airflow is reduced.

[0035] Furthermore, the cyclone 10 separates the transport air and removes the powder coating A, which has a small particle size and is difficult to adhere to the object B to be coated, thereby further improving the coating efficiency.

[0036] This invention is not limited in any way to the embodiments described above, and can be implemented in various other forms without departing from the spirit of the invention. The scope of this invention is defined by the claims, and includes all modifications within the meaning and scope of equivalents set forth in the claims. [Explanation of Symbols]

[0037] 2 Paint tanks 3. Electrostatic paint gun 5 Injectors 9 Paint hose 10 Cyclone 11. Second injector

Claims

1. A powder coating apparatus that sucks powder coating from a paint tank with an injector into which compressed air is supplied, transports the compressed air supplied to the injector via a paint hose to an electrostatic coating gun, and sprays the powder coating from the electrostatic coating gun onto a workpiece to adhere the powder coating to the workpiece by electrostatic force, wherein a cyclone is installed at the downstream end of the paint hose to separate the powder coating from the transport air from the multiphase flow of powder coating and transport air passing through the paint hose, the powder coating separated from the transport air by the cyclone is supplied to the electrostatic coating gun by a second injector, and the amount of air in the second injector is controlled to the minimum necessary to reach the workpiece.

2. The powder coating apparatus according to claim 1, characterized in that the cyclone removes small particle size powder coatings together with the conveying air.

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