JP4498965B2 - Corona-charged electrostatic paint gun - Google Patents

Description

  The present invention relates to a corona charging type electrostatic coating gun which generates a corona discharge at a corona pin electrode at the tip of a gun with a high voltage generator and applies a charge to a powder coating material passing through the electric field.

When using a corona-charged electrostatic coating gun to coat an object with a simple coating surface, such as a large flat plate, in general, the discharge rate of the powder coating is increased and the corona pin electrode is increased. The voltage applied to is adjusted to a maximum of 100 KV, for example, and coating is performed quickly in a short time.
On the other hand, when painting an object with a complex shape with irregularities, when painting with an emphasis on the skin of the coating film, or when baking after painting and then re-coating (recoating) While adjusting the discharge rate, gun distance, and voltage according to the painting, I have been painting carefully to prevent electrostatic repulsion.

By the way, conventionally, when painting using a hand gun, the painting operator adjusts the electric field at the tip of the gun while adjusting the voltage-current knob of the coating machine control panel along with the discharge amount and gun distance. Electric repulsion is prevented from occurring.
However, there is a problem that it takes time and effort for an on-site operator to check coating products from the painting site and adjust the coating machine control panel according to the preference of the on-site operator.

Also, the shape and size of the object to be coated can be adjusted by attaching a discharge nozzle called a flat nozzle that spreads the discharge pattern flatly at the tip of the gun, or by attaching a reflector at the tip of the gun that diffuses the discharge pattern round. The on-site operator selects a discharge pattern according to the above so that the painting is performed efficiently.
And when painting using a hand gun, you must change the movement of the painting gun according to the shape of the selected discharge pattern and the shape of the object to be coated, so that there are no paint residues or thin film parts, Skill is required to learn the movement. In particular, when painting a box-shaped object, the outer surface can be painted more efficiently if the distance between the corona pin electrode of the coating gun and the object to be coated is smaller. If the paint gun is too close to the inner corner, the corona pin electrode will be too close to the object to be coated, i.e. the ground object, and the voltage will decrease sharply. Since ions are attracted to the area around the nearest corner of the object to be electrostatically repelled, the paint gun must not be brought too close to the inner corner and the paint film must be finished cleanly. Such work is difficult unless it is an expert.

  Therefore, according to the present invention, the electric field can be easily adjusted according to the shape of the object to be coated and the discharge pattern without the operator having to leave the painting site and adjust the voltage-current knob of the coating machine control panel. Therefore, it is an object of the present invention to provide a corona-charged electrostatic coating gun that can be applied to a beautifully painted skin without being skilled.

  In order to solve the above-mentioned problems, the present invention makes it possible to move the mounting position of the discharge nozzle at the gun tip in the front-rear direction with respect to the corona pin electrode at the gun tip, or to move the non-conductive tube back and forth on the corona pin electrode. It was possible to adjust the electric field at the tip of the corona charging electrostatic coating gun by covering it as much as possible or by providing a corona pin electrode at the tip of the gun so that it could move back and forth.

  Therefore, the electric field can be adjusted by the operator without changing the shape of the discharge pattern, so that even a non-skilled person can easily apply clean coating of the coating film skin.

The first embodiment shown in FIG. 1 is a corona charging electrostatic coating gun in which a discharge nozzle 3 having an outlet portion for spreading a powder coating material flat is attached to a gun tip 2 of a gun body 1 so as to be movable in the front-rear direction. Is shown. The gun tip 2 is provided with a corona pin electrode 4.
1 can be moved in the front-rear direction with respect to the corona pin electrode 4 of the gun tip 2, the corona charging electrostatic coating gun of FIG. As shown in c), the distance between the corona pin electrode 4 and the outlet portion of the discharge nozzle 3 can be arbitrarily changed by the operator, and the painting operation can be performed while adjusting the electric field without changing the shape of the discharge pattern.
2 (a), 2 (b), and 2 (c), for example, in a state where a 300H × 500W steel sheet is to be coated A, and the distance from the coated object A to the corona pin electrode 4 is constant at 190 mm. FIG. 2A shows an example in which the distance between the tip of the discharge nozzle 3 and the object A is changed to 180 mm, FIG. 2B is 165 mm, and FIG. 2C is 150 mm. The article A is grounded via an ammeter, and the coating conditions are as follows.
Coating machine: SFC-H600 (X-1) manufactured by Asahi Sac
Powder coating: Epoxy polyester (Ivory) made by Takashi Kubo Paint
Coating current measuring device: SS-5000 electrostatic coating tester manufactured by SHEEN Co., Ltd. Coating conditions: Discharge rate 120 g / min, conveyor speed 1.0 m / min, reciprocating stroke 600 mm, reciprocating speed 20 m / min

  As a result of the above experiment, the distance between the tip of the discharge nozzle 3 and the object A decreases as the distance between the object A and the corona pin electrode 4 is constant as shown in Table 1. The current value to A (μA) decreased, and the coated skin was also improved. That is, the electric field can be adjusted by moving the discharge nozzle 3 back and forth. This is considered to be because free ions are confined in the discharge nozzle 3 by moving the discharge nozzle 3 forward.

  Next, using a hand gun, paint the box-type switchboard that opens on one side, and move the mounting position of the discharge nozzle 3 to the front side by 0 mm, 15 mm, and 30 mm on the outer, inner, and inner corners of the box. I painted it. The coating conditions were a discharge rate of 130 g / min, a voltage of 80 KV, and the coating workability, the coating around, and the state of the coating skin were confirmed when the mounting position of the discharge nozzle 3 was changed as described above. The results are shown in Table 2.

  Judging from the results shown in Table 2, with respect to the coating of the outer surface of the back surface, the coating can be efficiently performed when the distance between the outlet of the discharge nozzle 3 and the corona pin electrode 4 is shorter. On the other hand, with respect to the coating of the inner corner portion, when the distance between the outlet portion of the discharge nozzle 3 and the corona pin electrode 4 is increased, the coating around the corner portion is better, and electrostatic repulsion is also caused in the corner peripheral portion. It did not occur and the coating skin was found to be good. This is because when the corona pin electrode 4 gets too close to the object to be grounded, the voltage decreases rapidly, the electric charge to the powder coating particles is attenuated, and free ions emitted from the outlet of the discharge nozzle 3 It is thought that this is because electrostatic repulsion occurs due to being attracted to the nearest corner periphery of the object to be coated.

As described above, by adjusting the distance between the outlet portion of the discharge nozzle 3 and the corona pin electrode 4 according to the shape of the object to be coated, it is possible to paint a good coating film skin while preventing electrostatic repulsion. become.
And even if the distance between the outlet portion of the discharge nozzle 3 and the corona pin electrode 4 is changed, the spray pattern discharged from the discharge nozzle 3 does not change. However, it is possible to paint without leaving unpainted or thin film parts.

Next, in the second embodiment of FIG. 3, the electric field can be adjusted by covering the corona pin electrode 4 with the nonconductive tube 5 and moving the nonconductive tube 5 relative to the corona pin electrode 4. It is a thing.
As shown in FIG. 4, the distance from the corona pin electrode 4 to the coating object A is constant at 190 mm, and the distance from the tip of the discharge nozzle 3 to the coating object A is also constant at 180 mm. As shown in FIG. 4, the tip of the nonconductive tube 5 is positioned 5 mm behind the tip of the corona pin electrode 4, and the tip of the nonconductive tube 5 is connected to the tip of the corona pin electrode 4 as shown in FIG. The current value of the object to be coated A is measured when the positions are matched and when the tip of the non-conductive tube 5 is positioned 5 mm forward from the tip of the corona pin electrode 4 as shown in FIG. As a result, the results shown in Table 3 were obtained.

Next, in the third embodiment of FIG. 5, a corona charging electrostatic coating gun in which a discharge nozzle 3 provided with a reflection plate 6 at the tip is attached to the gun tip 2 of the gun body 1 so as to be movable in the front-rear direction. Show. The corona pin electrode 4 is installed so as to pass through the center of the reflecting plate 6. When the reflecting plate 6 is moved in the front-rear direction, the corona pin electrode 4 is protruded from the center of the reflecting plate 6 as shown in FIG. As shown in FIG. 6C, the corona pin electrode 4 can be accommodated in the reflector 6.
Note that the ejection pattern ejected from the ejection nozzle 3 does not change even if the ejection nozzle 3 provided with the reflection plate 6 at the tip is moved back and forth.
In Table 4, as shown in FIGS. 6A, 6B, and 6C, the distances from the object A to the corona pin electrode 4 are all constant at 190 mm, and the tip of the reflector 6 is shown in FIG. The tip position of the reflector 6 is located 5 mm behind the tip of the corona pin electrode 4 as shown in a), and the tip position of the reflector 6 is placed at the tip of the corona pin electrode 4 as shown in FIG. The current value of the object A to be coated when a coating experiment is performed in the combined state and in a state where the tip position of the reflector 6 is positioned 5 mm forward from the tip of the corona pin electrode 4 as shown in FIG. Is measured.

  From the results in Table 4, it was confirmed that the electric field can be adjusted without changing the discharge pattern by moving the discharge nozzle 3 provided with the reflecting plate 6 at the front and back.

It is a conceptual diagram which shows the gun | tip tip part of 1st Embodiment of the corona electrification type electrostatic coating gun of this invention. (A), (b), (c) is a conceptual diagram which shows the state which performs a coating experiment by moving a discharge nozzle back and forth in the corona electrification type electrostatic coating gun of FIG. It is a conceptual diagram which shows the gun | tip tip part of 2nd Embodiment of the corona electrification type electrostatic coating gun of this invention. (A), (b), (c) is a conceptual diagram which shows the state which performs a coating experiment by moving a nonelectroconductive tube back and forth in the corona electrification type electrostatic coating gun of FIG. It is a conceptual diagram which shows the gun | tip tip part of 3rd Embodiment of the corona electrification type electrostatic coating gun of this invention. (A), (b), (c) is a conceptual diagram which shows the state which performs a coating experiment by moving a reflecting plate back and forth in the corona electrification type electrostatic coating gun of FIG.

Explanation of symbols

1 Gun body 2 Gun tip 3 Discharge nozzle 4 Corona pin electrode 5 Non-conductive tube 6 Reflector

Claims (4)

  With a corona pin type electrostatic coating gun equipped with a corona pin electrode and a discharge nozzle attached to the gun tip that discharges powder paint, the mounting position of the discharge nozzle at the tip of the gun can be moved back and forth with respect to the corona pin electrode. Corona electrification type electrostatic painting gun.   A corona pin type electrostatic coating gun equipped with a corona pin electrode at the tip of a gun that discharges powder paint, and a discharge nozzle attached to the tip of the gun. Corona-charged electrostatic paint gun.   The corona charging electrostatic coating gun according to claim 1 or 2, wherein the discharge nozzle has a flat spray pattern. The corona charging electrostatic coating gun according to claim 1, wherein a reflection plate is attached to the discharge nozzle.

Images