JPS6136470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for controlling and adjusting the amount of air in air spray in powder coating.

This article provides an overview of conventional powder coating methods and equipment. As seen in FIG. 1, a porous plate 2 is provided substantially horizontally at the bottom of the powder supply tank 1 at a slight height above the bottom. First, the powder coating P is supplied to the upper surface of the porous plate in the supply tank, and then, pressurized air CA is sent under the porous plate to spread it over the porous plate in an area. The powder coating material on the porous plate is uniformly ejected (CA) into a floating state (PA). At the same time, the floating powder coating material is passed through the supply pipe 3 provided on the side of the powder supply tank to the action of the ejector 5 in the ejector type supply device 7 provided on the side of the supply tank. Then,
It is sucked in with the floating air (PA'), and is air-transported through the transport pipe or transport hose 11 together with the air blown out from the ejector to the spray gun 1.
Reach 0. and the spray gun nozzle 17
As a result, the powder paint PA is spray-coated onto the object 21 to be coated. However, in this case, since the amount and speed of air ejection are relatively large, the mixture PA〓 of air and powder paint collides with the object to be coated 21, rebounds (PA〓), and is compared with them. A large amount of powder paint
P″ is scattered in the air and consumed.The amount is about 45%.
It is said that the coating efficiency is reduced by 55%, that is, the coating efficiency is reduced by 55% to 45%.

As mentioned above, the reason why a large amount of high-speed air is required for spraying is to perform the ejector action described above, and as long as an ejector is used, it is difficult to suppress the amount of air.

An object of the present invention is to provide a powder paint and air mixture necessary for spraying on a pneumatic transport system between a supply device for a mixture of powder paint and air and a spray gun in a powder paint coating apparatus using an ejector. The purpose of this method is to draw out the excess amount of air that exceeds the appropriate amount, thereby preventing the powder paint from scattering in the air during spraying, and improving the coating efficiency.

The gist of the present invention is to provide a powder coating device using an ejector on a transport pipe or a transport hose between a supply device for a mixture of powder paint and air and a spray gun, or near a nozzle mounting part inside the spray gun. The present invention provides a method and an apparatus for controlling and adjusting the necessary and appropriate amount of air for spraying through the openings for air extraction.

Next, the method according to the present invention will be explained. Please refer first to FIG. 1, which illustrates the conventional method described above. The difference between the method of the present invention and the conventional method is that
The purpose is to draw out excess air beyond that required for spraying from a certain point on the transport path of the mixture of powder paint and air between the supply device 7 and the spray gun nozzle 17 shown in the figure. . The method for pulling it out is to provide an opening at the above-mentioned location, and further provide a mouth tube in the opening,
Alternatively, connect an exhaust pipe or the like to the mouth pipe and forcefully exhaust the air from the other end, or use a pipe with a different diameter in the middle of the transport pipe and provide an opening for air extraction on the large diameter pipe. Furthermore, there are various methods such as providing an air flow rate adjusting device in the middle of these exhaust pipes, but since these are all embodiments, they will be explained in detail in the next device section.

The basis of the apparatus according to the method of the invention is a mechanism for drawing off an excess amount of air, above that required for spraying, from a point on the pneumatic transport path of the powder coating and air mixture. The above passage can be roughly divided into the following three points.

1. An intermediate part of the transport pipe or transport hose for the mixture of powder coating and air between the supply device and the nozzle.

2 Near the outlet of the supply device or the connection between the outlet and the transport pipe.

3 Near the attachment part of nozzle 15 in the spray gun.

In the part 1 listed above, the opening part 1
2, 42, 44 or their respective parts, and in item 2, the opening parts 14, 67 or their respective parts have mouth pipes 15, 68, respectively. In item 3, the openings 18 and 75 or the mouth pipes 19 and 76 are attached to each of the openings 18 and 75, respectively.

Next, various aspects of the exhaust pipe connected to the above air extraction port pipe will be described.

(1) As shown in Fig. 2, a mouth pipe 43 for drawing air is provided on the transport pipe 31 or the pipe joint, almost perpendicular to the direction of the pipe, and the mouth pipe and the exhaust device are connected to each other.
Connected to EX with piping 51.

(2) As shown by the imaginary line in FIG. 2, a different diameter joint 40 is provided on the transport pipe or transport tube, and the thinner end 40S is connected to the spray gun 32, and the thicker end is connected to the supply device, and A port pipe 45 or 46 for air extraction is provided on the large diameter pipe of the different diameter joint at a nearly right angle or at an acute angle (“α”) to the direction of the thin diameter pipe, and these port pipes are used as an exhaust device. connected by piping.

(3) As shown in FIG. 3, near the outlet of the supply device 63 or the connection between the supply device and the transport pipe 65, a mouth pipe 68 for drawing out air is provided approximately at right angles to the outlet, The mouth pipe and the exhaust device EX ₄ are connected by a pipe 69.

(4) As shown in FIG. 4, a mouth pipe 76 for air extraction is provided at a location immediately in front of the nozzle 77 attached to the tip of the spray gun 72, and the mouth pipe and exhaust device EX ₃ are connected to the pipe 78. to be connected.

(5) An air flow regulating device AR is installed on the piping connecting each of the air extraction mouth pipes and the exhaust device in paragraphs (1), (2), (3), and (4) above. .

As mentioned above, there are variations in the exhaust pipes provided on the transportation system after the mouth pipe for drawing out air by various combinations.

According to the results of experiments using the device of the present invention, the amount of powder paint mixed with the air and pulled out during the air drawing operation is only 1% to 2%.
It has been proven that this is rarely a problem. Therefore, the amount of spray air necessary and appropriate for powder coating spraying by the method and apparatus of the present invention is such that the amount of reflection on the object to be coated is small, the scattering of the powder coating is also small, and the coating efficiency is 65%. % to 70%, which not only contributes to resource conservation, but also greatly contributes to the improvement of environmental hygiene by reducing the scattering of powder paint.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram of a conventional ejector-type powder coating device and the present invention, and FIG. 2 is a cross-sectional view of an air extraction device provided on the air transport system for a mixture of powder coating and air according to the present invention. Explanatory drawing, Fig. 3 is a cross-sectional explanatory drawing in which an air extraction device is provided near the connection between the ejector type supply device and the transport pipe according to the present invention, and Fig. 4 is an explanatory drawing.
The figure is a cross-sectional explanatory view of an air drawing device provided near the nozzle handle of the spray gun according to the present invention. Explanation of main symbols 1, 61... Powder floating tank, 2... Porous plate, 7... Ejector type supply device,
10, 32, 66, 72... spray gun, 11,
31, 65, 71...Air transport pipe or hose, 1
2, 14, 18, 42, 44, 67, 75...Air extraction hole, 13, 15, 19, 43, 4
5, 46, 68, 76...Air extraction mouth pipe, 1
7, 77... Nozzle, 40... Different diameter tube, 51, 52,
53, 69, 78...Exhaust pipe or hose, AR...Air flow regulator, CA...Compressed air, EX...Exhaust device,
P...Powder paint, PA...Mixture of powder paint and air.

Claims (1)

[Scope of Claims] 1. A method for supplying a powder coating material to a spray gun by pneumatic transport via an ejector-type supply device, comprising: a nozzle of the spray gun; a supply device for a mixture of powder coating material and air; A powder coating method characterized by drawing out excess air in excess of that required for the spraying action of the powder coating on the air transport system between the powder coatings. 2. In a powder coating device consisting of a spray gun 10 connected to an ejector type supply device 7 directly connected to a powder floating tank 1 by a transport pipe 11 or a transport hose, the inside of the transport pipe or transport hose or the spray gun is A powder coating apparatus characterized in that air extraction holes 12 or 14, 18 are provided on a transportation system. 3. On the transport pipe or transport hose 11 (or 31), there are holes 12 or 14 (or 4) for air extraction.
2) The powder coating apparatus according to claim 2, characterized in that a mouth pipe 13 or 15 (or 43) is provided on the part. 4 Place the mouth pipe 15 on the air extraction opening 14 (or 67) immediately after the ejector device 7 (or 63).
(or 68) The powder coating apparatus according to claim 2, characterized in that the powder coating apparatus is provided with (or 68). 5. It is recommended that the mouth pipe 19 (or 76) be provided above the air extraction opening 18 (or 75) provided near the attachment part of the nozzle 17 (or 77) at the tip of the spray gun 10 (or 72). A powder coating apparatus according to claim 2, characterized in that: 6 Connect the thinner end (40S) of the transport pipe or transport hose connected with the different diameter pipe joint 40 to the spray gun 32, and the thicker end to the ejector type supply device, and connect the A patent characterized in that a mouth tube 45 is provided on the air extraction opening 44 provided in the tube at a substantially right angle to the tube, or a mouth tube 46 is provided at an acute angle "α" to the thin tube direction of the tube. A powder coating apparatus according to claim 2. 7 Mouth pipe 43 or 45, 46 for air extraction,
Connect exhaust pipes or exhaust hoses 51 or 52, 53, 69, 78 to 68, 76, etc., respectively,
Claim 3 or 4, characterized in that an exhaust device EX or EX ₁ , EX ₂ , EX ₃ , EX ₄ or the like is provided at the other end of these exhaust pipes or exhaust hoses.
5. The powder coating apparatus according to Items 5 and 6. 8. The powder coating apparatus according to claim 7, characterized in that a flow rate adjustment device AR is provided in front of the exhaust device EX or EX ₁ , EX ₂ , EX ₃ , EX ₄ , etc.