JPH0130541B2 - - Google Patents

Description

[Detailed description of the invention] The present invention provides an electrostatic powder coating machine, a liquid electrostatic coating machine,
Alternatively, the present invention relates to a particle charging device for applying a similar electrostatic charge to a liquid or powder.

Conventionally, as shown in FIG. 2, when charging particles transported in a pipe a at a pipe outlet b, a discharge electrode c is installed at the pipe exit b, and a power source d is connected to the discharge electrode c. Electricity is supplied from the discharge electrode through a conductor e, and corona discharge is performed from this discharge electrode toward a grounded counter electrode or the object to be coated f, thereby charging the particles. In this case, since the particles are charged at the outlet b of the conduit, the charging efficiency is likely to change depending on the flow of the particles and the shape of the opposing electrode. Therefore, as shown in Fig. 3, a ring-shaped electrode A ring-shaped electrode g is provided to pre-charge particles in the pipe a, and then the particles are charged again at a discharge electrode c at the pipe outlet b.

In the device shown in FIG. 3, a constant charging efficiency can be obtained without affecting the flow of the air particles at the outlet b of the conduit, but in order to supply power to the discharge electrode c, together with the power supply d,
The power source d and a power source with a different voltage are connected to a ring-shaped electrode g.
It was necessary to supply power through conductor h.

In addition, in this type of charging device, there is an air supply path for adjusting the discharge pattern of particles, an air supply path for cleaning the corona discharge electrode c, or an air supply path for cleaning particles attached to the inner surface of the ring-shaped electrode g. An air supply path for cleaning is provided. Therefore,
This method has the disadvantage that the conductor wiring for feeding power to each of the electrodes, its insulation structure, and power feeding mechanism are complicated.

Furthermore, when a ring-shaped electrode g (counter electrode) is provided on the inner wall surface of the conduit a, the diameter of the electrode g becomes larger.
Its surface area also increases.

Therefore, since the area in contact with the powder becomes larger, the powder becomes more likely to adhere, and the reverse ionization phenomenon becomes more likely to occur.

In view of the above circumstances, it is an object of the present invention to provide a particle charging device with simple wiring and high charging efficiency.

The present invention provides a particle charging device in which a central body is provided on the central axis of a conduit, in which an internal discharge electrode connected to a high voltage power source is provided in the conduit, and the central body is opposed to the internal discharge electrode. The above object is achieved by providing a receiving electrode, an external discharge electrode at the tip of the central body, and electrically connecting the external discharge electrode and the receiving electrode.

The present invention will be explained below based on the embodiment shown in FIG.

In FIG. 1, a plurality of needle-shaped internal discharge electrodes (primary discharge electrodes) 2 are installed on the outer wall of a conduit 1 that transports particles so as to face the central axis of the conduit 1, and these primary electrodes 2 are connected to a conductive wire. 3 to a high voltage power supply 4.

A center body 6 is provided at the center of the outlet portion 1a of the conduit 1 via a support arm 5, a receiving electrode 7 is provided on the center body 6 so as to face the internal discharge electrode 2, and a needle is provided at the tip of the center body 6. An external discharge electrode 8 having a shape is provided, and the receiving electrode 7
and the external discharge electrode 8 are electrically connected. In the above configuration, when a high voltage is applied to the internal discharge electrode 2, a corona discharge is generated from the internal discharge electrode 2 toward the receiving electrode 7, and this corona discharge charges particles passing through the pipe 1. give. The potential of the receiving electrode 7 increases as it receives this corona discharge, and due to this potential, a corona discharge is generated from the external discharge electrode 8 toward the grounded counter electrode or the object to be coated 9, and the conduit 1 imparts a charge to the particles at the exit of the

In the above-mentioned embodiment, various air supply paths are provided in the same manner as in the prior art, although they are not shown. Furthermore, the particles are the same not only as powder particles but also as liquid particles.

Since the particle charging device according to the present invention is configured as described above, it has the following remarkable effects.

(1) Corona discharge can be performed without direct wiring to the discharge electrode, and at the same time internal charging can be performed within the conduit.

Furthermore, since the wiring is only connected to the internal discharge electrodes, the wiring and insulation structure can be made extremely simple.

(2) Since the powder flowing through the pipe is dispersed toward the pipe wall by the central body, the powder passes near the internal discharge electrode where the ion concentration is high.

Therefore, charging efficiency can be improved.

(3) An internal discharge electrode connected to a high-voltage power source is provided in the conduit, and a receiving electrode facing the internal discharge is provided in the central body, so that the diameter of the receiving electrode is smaller than that of the conventional ring-shaped electrode. That's small.

Therefore, since the surface area of the receiving electrode can be reduced, the area in contact with the powder body can also be reduced compared to the conventional example.

Therefore, the adhesion rate of the powder to the receiving electrode is reduced, so that no reverse ionization phenomenon occurs.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing a conventional example. 1...Pipe line, 2...Internal discharge electrode, 7...Receiving electrode, 8...External discharge electrode, 4...High voltage power supply.

Claims (1)

[Claims] 1. In a particle charging device in which a central body is provided on the central axis of a conduit, an internal discharge electrode connected to a high voltage power source is provided in the conduit, and a receiving electrode facing the internal discharge is provided in the central body. Further, a particle charging device comprising an external discharge electrode provided at the tip of the central body, and electrically connected to the external discharge electrode and the receiving electrode.