JPS6140470B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an airless electrostatic coating device, and more specifically, a convex portion is provided at a position as close as possible to the electric field electrode at the tip of the conductive handle portion, which serves as the counter electrode of the airless electrostatic gun, to facilitate concentration of the electric field. This invention relates to an airless electrostatic coating device that can maintain stable performance by increasing the effectiveness of the electric field electrode provided at the tip of the spray nozzle. Generally, in electrostatic painting, a high voltage applied to an electrode at the tip of a nozzle discharges a nearby conductive object (grounded object), and the closer the distance to the conductive object, the greater the amount of discharge. Therefore, as the amount of discharge increases, the air near the tip of the electrode becomes more highly ionized, and the amount of charge on paint particles passing near it increases, and at the same time, the electric field becomes stronger. surrounding effect) is improved. However, in general, in order to obtain an electrostatic effect, the distance between the tip electrode of an electrostatic gun and the object to be coated is around 30 cm, and with a hand gun, this distance is not constant due to the painting, so the amount of discharge to the object to be coated is It becomes extremely unstable. For this reason, a method has conventionally been adopted in which a counter electrode is provided at the rear of the electrostatic gun, and a stable discharge is performed from the electrode at the tip toward the counter electrode to maintain the electrostatic effect at all times. However, in this type of handgun, since the conductive body of the handle portion is normally used as a counter electrode, sufficient discharge is not performed, which has been a problem in accelerating electrostatic effects. Of course, if the conductive part of the handle is brought closer to the electrode, the amount of discharge will increase, but naturally the internal discharge through the paint passage will increase, the potential of the electrode at the tip will decrease, and an electrostatic effect can be expected. become unable. In view of the above-mentioned circumstances, the present invention provides a convex portion on the conductive portion of the electrostatic gun handle serving as the counter electrode, thereby promoting discharge from the tip electrode toward the counter electrode and discharging the charge at the tip. By configuring the electrode as a combination of a charged electrode and a floating electrode, discharge to the floating electrode is promoted and the ionization region generated near the electrode at the tip is strengthened, thereby enhancing the electrostatic effect. Hereinafter, the present invention will be explained with reference to drawings of embodiments. The airless electrostatic gun 1 has a barrel section 2 made of an insulating material, a conductive handle section 3, and a tip atomizing section 4 provided at the tip of the barrel section 2. The barrel section 2 has a paint passageway at the top. A needle valve 6 is provided vertically through the gun barrel 2, and a needle valve 6 is provided so as to be able to move forward and backward by operating a trigger 7.A high resistance element 8 is cast in the lower part of the barrel part 2 at its tip, and a high voltage cable insertion hole 9 is provided at the other end. An insulated L-shaped casing 10 having a shape formed therein is fitted over the handle portion 3,
The electrical passage section 11 is connected to the paint passage 5 within the gun barrel section 2.
It is located separately from the The handle portion 3 is made of a conductive material, has a protruding hook portion 12, and is fixed and integrally formed with the gun barrel portion 2 at the upper portion of the handle portion 3. The lower part of the handle part 3 contains the other of the L-shaped casing 10 made of an insulating material fitted into the gun barrel part 2, and a high voltage cable 13 connected to a high voltage generator (not shown) is connected to the L-shaped casing. 10 is inserted into the high voltage cable insertion hole 9. 14 is a metal paint pipe that also serves as a safety guard for the trigger; its base end is fixed to the base end of the handle portion 3 with a conductive binding plate 15; its tip passes in front of the trigger 7; It passes through the side of the gun barrel part 2 from below and is connected to a joint 16 provided on the side of the handle part 3, and the paint is supplied from the joint 16.
It passes through the sleeve 17 and is sent to the paint passage 5 side. 18 is a needle valve gasket, and 19 is a needle valve pressing spring. Further, the tip atomizing section 4 provided at the tip of the gun barrel section 2 has a nozzle tip 21 having a spray nozzle opening 20 in the center.
A tip holder 22 fitted with a tip holder 22 is attached to the gun barrel 2 by a cover 23, and the tip holder 22 has a charged electrode 24 having a pointed end slightly in front of the nozzle tip 21 and slightly away from the injection axis a. In addition, a floating electrode 25 is provided opposite to the charging electrode 24 across the paint injection axis a. The floating electrode 25 has a disk-shaped power-receiving electrode 26 which is a power-receiving part in the part facing the charging electrode 24, and a part thereof extends forward to form a pin-shaped electric field electrode 27, so that the floating electrode 25 is in an electrically floating state. The high voltage is discharged from the charged electrode 24 to the very close receiving electrode 26, and then from the tip of the electric field electrode 27 extending forward from the receiving electrode 26 to the object to be coated and the gun handle portion 3 which becomes the counter electrode. A discharge occurs between the two, forming an electric field. Note that the charging electrode 24 is connected to the chip stand 22 when it is connected to the cover 2.
2, the conductive ring 28 on the rear surface of the tip holder 22 comes into contact with the tip 29a of the electrical passage 29 protruding from the tip of the barrel 2 to maintain the energized state. The conductive ring 28 is electrically connected to the charging electrode 24. The electrostatic airless gun of the present invention is constructed as described above, and has a conductive handle portion 3 serving as a counter electrode.
A convex portion 14a is formed protruding from a part of a metal paint pipe 14 which also serves as a safety guard and is placed in front of the handle portion 3 at a position as close to the charging electrode 24 as possible. The shape of the convex portion 14a is not specified as long as it is a protrusion that can easily concentrate an electric field in order to exert a counter-electrode effect. Alternatively, instead of the protruding part 14a formed protruding from the paint pipe 14, a protruding part 12a may be provided at the tip of the conductive hook part 12 protruding from the upper part of the conductive handle part 3 at a position as close to the charging electrode 24 as possible. By forming such a structure, the opposing electrode effect can be exerted. Next, the operation of the present invention in the above configuration will be explained. First, when the handle portion 3 is grasped and the trigger 7 is pulled, the needle valve 6 is moved back and the paint passes through the paint passage 5 and enters the nozzle at the tip. A high voltage cable 13 in an L-shaped casing 10 that is sprayed from a mouth 20 and a high voltage is contained in a handle part 3 and a gun barrel part 2;
The tip atomizer 4 passes through the electrical passage section 11 and the high resistance body 8.
is supplied to the charging electrode 24 of. When a high voltage is supplied to the charging electrode 24, the charging electrode 24 discharges across the paint film sprayed from the nozzle port 20 to the disc-shaped receiving electrode 26 of the opposing floating electrode 25, promoting ionization. In addition to effectively charging the paint, a discharge is generated from the tip of the electric field electrode 27 extending forward from the power receiving electrode 26 toward the object to be coated, thereby forming a stable electric field between the objects to be coated. Further, the electric field electrode 27 generates an electric field by discharging between it and the counter electrode, i.e., the handle portion 3 of the gun, but in the case of the present invention, simply using the conductive handle portion 3 as the counter electrode. Rather, the electric field electrode 27 may be connected to a part of the metal paint pipe 14 located as close as possible to the electric field electrode 27 on the handle portion 3 or at the tip of the hook portion 12 at the top of the handle portion 3.
By forming the convex portion 14a or the convex portion 12a in a protruding manner at a position close to the convex portion 14a or the convex portion 12a, the electric field from the electric field electrode 27 is concentrated on the convex portion 14a or the convex portion 12a, enhancing the opposing electrode effect and forming a stable electric field. . Additionally, in an experiment conducted by the present inventor, the electrostatic effect when 14 parts of the metal paint pipe were provided with a convex portion and when there was no convex portion is shown in the table below (the shape of the convex portion is (φ=2 mm, l=2 mm).

[Table] That is, as shown in the above table, by providing a convex portion as a counter electrode, the turning value is improved and the handle return current value is increased. An increase in the handle return current value can be seen as a discharge of a certain degree of strength, which means that the discharge is stable even when the surrounding conditions around the electrode change, such as when the electrode approaches a grounded object, that is, the performance is maintained. This means that it can be maintained. As described above, the present invention includes a charged electrode that receives a high voltage supply and discharges in the tip atomizing section, and a power receiving electrode that receives discharge from the charged electrode across the paint film sprayed from the nozzle opening. The floating electrode is composed of an electrode and an electric field electrode extending forward from the power receiving electrode, and a counter electrode is placed as close as possible to the conductive paint pump or hook in the gun handle part. By forming a convex part that concentrates the electric field, the sprayed paint is charged by discharge from the charged electrode to the floating electrode across the sprayed paint film, promoting ionization and creating an effect on the paint. In addition to being electrically charged, the floating electrode creates a stable electric field between the convex part of the handle that serves as the counter electrode and the object to be coated, regardless of the paint atomization area or condition, further enhancing the electrostatic effect. I can do it. In other words, by providing a floating electrode, the electric field electrode at the tip of the floating electrode divides the electric field formation, making the electric field to the object to be coated stronger (increasing the current) and reducing the supply current compared to the case of a single charged electrode. As this increases, the discharge at the charging electrode becomes stronger, and the paint charging current to the object to be coated increases. Furthermore, in the case of a single charged electrode, it is necessary to place the electrode away from the most effective position (near the atomization area) in order to prevent the discharge effect from decreasing due to paint adhesion. However, according to the present invention, by providing a floating electrode, the functions of the charging electrode and the floating electrode are separated, and the charging electrode promotes ionization by discharging to the floating electrode, effectively charging the paint, The floating electrode creates a stable electric field between the opposing current and the object to be coated, regardless of the atomization area or atomization state of the paint, and can always enhance the electrostatic effect.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view, and FIG. 2 is an enlarged sectional view of the tip atomizing section. 1... Airless electrostatic gun, 2... Gun barrel, 3...
...Handle part, 4...Tip atomizing part, 5...Paint passage, 11...Electric passage part, 12...Hook part, 1
2a...Protrusion, 14...Paint pipe, 14a...
Convex portion, 20... Spray nozzle, 24... Charged electrode,
25...Floating electrode, 26...Power receiving electrode, 27...Electric field electrode.

Claims (1)

[Scope of Claims] 1. A high-potential charged electrode is provided at the tip of a gun barrel formed of an insulating material and containing a paint passage and an electrical passage,
In an electrostatic coating device having a counter electrode member made of a conductive material and maintained at a ground potential with respect to the charged electrode at the rear of the gun barrel, a disc-shaped opposing surface disposed apart from the charged electrode is provided. An electrically insulated floating electrode is provided which has a power receiving part with a needle-shaped electric field electrode extending forward toward the object to be coated, and the paint is applied between the charged electrode and the power receiving part. At the same time as opening the spray nozzle through which the
An airless electrostatic coating device characterized in that a convex portion is formed on a portion of the opposing electrodes at a position as close to the electric field electrode as possible, with its tip facing toward the electric field electrode. 2. The airless electrostatic coating device according to claim 1, wherein the convex portion is formed in a part of a conductive paint pipe disposed in front of the handle portion. 3. The airless electrostatic coating device according to claim 1, wherein the convex portion is formed at the tip of the conductive hook portion protruding from the upper portion of the handle portion.