JPS5833031B2 - Seidenfuntai Souhouhou Oyobi Souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention applies to coating objects to which a high voltage is applied in an air stream in which uncharged powder coating particles are evenly dispersed, especially objects having a complex shape with many irregularities. The present invention relates to a powder electrostatic coating method and apparatus capable of arranging objects and uniformly coating the entire surface to be coated.

The electrostatic powder coating method, in which powder paint is attached to the surface of the object to be coated using electrostatic adhesion, is well known, and the most common method used is Starfield (product name). There are two methods: electrostatic levitation, which uses a spray gun, and electrostatic spraying, which uses a spray gun.

The common and essential structural feature of both of these is that a charged electrode maintained at a high voltage for charging the paint powder is placed facing or opposite the object to be coated, and the charged powder particles are transferred to the charged electrode. The object is strongly attracted to the surface of the object by the electrostatic force of the electric field formed between the object and the counter electrode.

According to such conventional methods, when painting an object with a flat surface such as a plate, a very satisfactory painting effect can be obtained, but when painting an object with a complex shape with many irregularities, it is difficult to paint. When applying this, a non-uniform electric field is formed between the charged electrode and the workpiece, with electric lines of force concentrated on the convex parts of the workpiece, and as a result, only a small amount of paint is deposited on the concave parts of the workpiece. Does not stick,
In some cases, the coating may not adhere at all, resulting in an extremely unfavorable coating state.

Therefore, in the past, electrostatic powder coating methods have not been employed at all for articles with complex shapes, especially relatively small articles for which correction coating is not possible.

The present invention was made in view of the above-mentioned situation, and an object of the present invention is to provide a new electrostatic powder apparatus method and apparatus that can reliably apply good coating even to small articles with complex shapes. .

According to this invention, an object to be painted is placed in a powder-dispersed airflow formed by uniformly dispersing paint powder in an airflow that flows relatively slowly in one direction, and a high DC voltage is applied to the object to be painted. Accordingly, there is provided an electrostatic powder coating method characterized in that the floating paint powder is collected and adsorbed onto the surface of the object to be coated by electrostatic force.

Further, according to the present invention, there is provided a powder dispersion airflow supply path comprising an airflow generation means and a paint powder dispersion means, a sealable object loading port, and a means for supplying high-voltage beads to the object to be painted installed inside. An electrostatic powder coating apparatus is provided, which has a coating chamber that communicates with the powder dispersion air flow supply path, and an exhaust path that communicates with a portion of the coating chamber that faces the powder dispersion air flow supply path.

The present invention will be described in detail below with reference to illustrative examples.

Reference numeral 1 denotes a powder dispersion airflow supply path, in which a fan 2 and a powder disperser 3 shown as an example of airflow generation means are disposed.

Reference numeral 4 indicates a filter arranged as necessary, and reference numeral 5 indicates a damper for blocking airflow or adjusting the amount of air.

A unidirectional airflow is generated within the supply path 1 by a fan 2.

Powder paint supplied from the paint supply device 6 is discharged from the disperser 3 into this airflow, and is dispersed in the supply path 1 at a uniform density.

The dispersant particles are transported to the coating chamber 7 communicating with the supply path 1 by an air current flowing at a relatively slow speed, usually 1 mAec or less.

Note that 8 is a compressed air source for feeding paint.

The coating chamber 7 is formed of an insulating material such as vinyl chloride, or at least the inner wall surface is coated with an insulating material, and the object 10 to be coated is arranged in the chamber so as to be located in the powder dispersion airflow. There is.

The object to be painted 10 is held by a suitable jig 11, and is preferably held in a positional relationship such that the surface to be painted is along the direction of air flow.

It goes without saying that the number and position of the objects to be painted and the structure of the jig 11 are determined by the shape of the objects to be painted.

A DC high voltage is applied to each workpiece 10 from a high voltage generator 12 via a supply cable 13, an appropriate connection connector 14 arranged in the coating room 7, and a distribution line on the jig 11. Ru.

The jig 11 is removably attached to the coating chamber 7, and the object to be coated 10 is taken in and out together with the jig 11 through a loading port 15 provided in the coating chamber.

The loading port 15 can be sealed by a door 16, so that the painting chamber 7 is completely shut off from the outside air during painting work.

Reference numeral 18 denotes an exhaust path that faces the airflow supply path 1 and is connected to the painting chamber 7, and the airflow that has passed through the painting chamber 7 and excess paint particles that have not adhered to the object to be painted are discharged into this exhaust path 18. Inflow.

Excess paint is also collected by a suitable collection device 19 such as a bag filter or cyclone.

A feature of the present invention is that the paint particles discharged from the disperser 3 into the supply duct 1 are dispersed in an uncharged state, and when passing near the object to be coated 10 to which a high voltage is applied, each particle is dispersed. An electric field is formed between the paint particles and the object to be painted, so that the paint particles are electrostatically attracted to the painted surface.

Therefore, it can be said to be an electrostatic collection method in which paint particles floating in an air stream are collected on the surface of the object to be coated, which is a charging electrode.

This allows for sufficient air flow even over the recessed painted surface, not only for items with flat surfaces, but also for items with complex shapes with many uneven surfaces, such as motor housings with many protruding heat dissipation fins. If the position and orientation of the object to be coated is considered so that the paint particles pass through, and if the powder dispersion airflow is formed so that the paint particles are evenly distributed, the adhered paint will be unevenly distributed between the concave and convex painted surfaces. The paint can be applied uniformly over the entire surface to be painted, making it possible to apply extremely good powder coating.

FIG. 3 schematically shows a coating apparatus configured to connect the starting end of the airflow supply duct 1 and the end of the exhaust duct 18 so that airflow circulates.

Both ducts N, 18 and the painting chamber 7 are similar to those shown in FIG.
5, an air intake hole 26 with a flow rate adjustment mechanism is provided between the recovery device 25 and the air circulation machine 2, and an air flow path is provided between the air circulation machine 2 and the powder dispersion machine 3. Change duct 2
8 are arranged respectively.

High voltage generator 12, paint disperser 3 and airflow modification duct 2
8 are operated in conjunction with a suitable control circuit, and the object 1 to be coated is
0 is set in the coating chamber 7 or taken out from the coating chamber, the high voltage is turned off, the disperser 3 stops discharging the paint, and the change duct 28 is further opened and the airflow flows to the change duct side.

Further, when the object to be coated is taken out, the high voltage is turned off and the electrical charges on the object to be coated are discharged.

It is also possible to automatically open and close the door 16 of the painting room 7 and take the object held on the jig into and out of the painting room.

The powder paint dispersing machine 3 is of the type that sprays paint from the lower part of the duct as shown in Fig. 1, or of the type that discharges the paint in the direction of airflow as shown in Fig. 3.
Furthermore, a type that shakes out the particles by applying vibrations from the upper part of the duct may be selected as necessary.

The thickness of the coating film is determined by the speed of the airflow, the amount of paint discharged, and the electrical current.

As described above, the present invention is completely revolutionary in that it is possible to apply powder coating extremely well even to relatively small and complex-shaped articles, which was previously considered impossible.

In addition, since the painting chamber is a closed type, there is no risk of outside air flowing in and disturbing the powder dispersion airflow or paint powder leaking outside, which is extremely superior in terms of workability and pollution prevention. Not only is it easy to recover excess paint, but it also has many advantages, such as being economical.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a partially cutaway enlarged perspective view of a painting room, and FIG. 3 is a schematic configuration diagram showing another embodiment. 1 is a powder dispersion airflow supply path, 2 is an airflow generation means, 3 is a paint powder disperser, 7 is a coating room, 10 is a double coated object, 11 is a jig, 12 is a high electric motor generator, and 18 is an exhaust path.

Claims (1)

[Claims] 1. An object to be painted is placed in a powder-dispersed airflow formed by uniformly dispersing paint powder in an airflow that flows in one direction at a relatively slow speed, and a high DC current is applied to the object to be painted. An electrostatic powder coating method characterized in that a voltage is applied to cause floating paint particles to be collected and adsorbed onto a painted surface by electrostatic force. 2. A powder dispersion airflow supply path comprising an airflow generation means and a paint powder dispersion means, a sealable object loading port and a means for supplying a high-voltage box to the object to be painted disposed therein. An electrostatic powder coating apparatus comprising: a coating chamber communicating with a powder dispersion air flow supply path; and an exhaust path facing the powder dispersion air flow supply path and connected to the coating chamber.